An amphibious all terrain mobile robot is required for disaster response tasks. In this paper, we propose “R-Crank”, which has a simple four wheels driving configuration with crank links, connecting to ipsilateral front and rear wheels so as to form parallel four-bar linkage systems. The crank links act as legs because their trajectory with respect to the ground become trochoid curve, which is commonly used as leg trajectories for a legged robot. These links achieve high terrain adaptability while maintaining simple structure of the wheeled robot. We developed a prototype model and carried out basic experiments. The robot achieved to climb 0.3 m of a step(76.9% of the wheel diameter), stairs and a snowy slope. In addition, we propose amphibious structure of crank links by installing multiple rigid paddles. The propulsive force generated by the crank links was measured and empirically derived the optimum parameters by using a small-sized experimental apparatus. Finally the robot equipped with the amphibious crank links achieved propulsion on water at 0.13 m/s. We also verified that the robot achieved going up and into water through stairs.

Generally, wheel mechanisms are inferior to a tracked or walking mechanism in terms of step climbability or traversability in rough terrain; however, they are superior in terms of energy efficiency, structural simplicity, and carrying capacity. This paper proposes a new wheel mechanism, the swing-grouser wheel, which can climb high steps (especially in low friction environments) and has high energy efficiency. In addition, the swing-grouser wheel can climb regardless of the body inclination. Its merits are compared to the results of prior studies. Furthermore, the performance of the swing-grouser wheel was confirmed using a real device experiment and a 2D physics simulation, and improved using a full search of the parameters of the swing-grouser wheel. As a result, one improved parameter resulted in climbing at over 68% of the wheel diameter in a low friction environment; additionally, the energy efficiency was better than that of the previous model.

Very long-reach snake-like robotic arms in the range of 14 meters are expected to be used in decommissioning work inside nuclear reactor containers. We developed a tendon-driven system which has the advantage of placing electronic devices protected in the arm's base part which stays out of the reactor container, and only few expensive highly radiation hardened sensors and tools are mounted in the arm tip. Generation of large joint torque is necessary to realize such a very long arm. We applied the concept of coupled tendon-driven mechanism formerly used to generate restricted two dimensional motions, and extended its concept by proposing a new joint arrangement which makes possible three dimensional motions in a large workspace. Mechanical design, compact storage method and derivation of the arm motion control are detailed. Moreover, we built a preliminary mechanical prototype called ”Mini 3D CT-Arm”, and the experimental results demonstrated the validity of the newly proposed concept.

In this paper, we present a new in-pipe robot with independent underactuated parallelogram crawler modules, which can automatically overcome inner obstacles in the pipes. The parallelogram crawler modules are adopted to maintain the anterior-posterior symmetry of forward and backward movements, and a simple differential mechanism based on a pair of spur gears is installed to provide underactuated mechanisms. A central base unit connects each crawler module through foldable pantograph mechanisms. To verify the basic behavior of this robot, primary experiments in pipes with different diameters and at partial steps were conducted.

In this paper, two types of biologically inspired educational robots based on gliding locomotion are presented. Gliding locomotion utilizes the difference between two orthogonal reaction forces to propel. Since this locomotion principle is very interesting and difficult to intuitively understand, its way of locomotion effectively evokes intellectual curiosity of students. One actuated degree of freedom (DOF) fish-like educational robot and its lecture program are developed for primary, junior high and high school students. And a snake-like educational robot which can connect arbitrary number of units, and its lecture program are developed for university students. We carried out these programs through several lectures. The results are also discussed in this paper.

In this paper, we discuss the development of the sprawling-type quadruped robot named “TITAN-XIII” and its dynamic walking algorithm. We develop an experimental quadruped robot especially designed for dynamic walking. Unlike dog-like robots, the prototype robot looks like a four-legged spider. As an experimental robot, we focus on the three basic concepts: lightweight, wide range of motion and ease of maintenance. To achieve these goals, we introduce a wire-driven mechanism using a synthetic fiber to transmit power to each axis making use of this wire-driven mechanism, we can locate the motors at the base of the leg, reducing, consequently, its inertia. Additionally, each part of the robot is unitized, and can be easily disassembled. As a dynamic walking algorithm, we proposed what we call “longitudinal acceleration trajectory”. This trajectory was applied to intermittent trot gait. The algorithm was tested with the developed robot, and its performance was confirmed through experiments.

In recent decades, the devastating earthquakes, which can damage a lot of houses and buildings, have frequently happened. To slow down or prevent the disastrous damages of the earthquake, the various technologies have been required. Of these technologies, the ground motion simulator of the earthquake can be used to alert people to the dangers of the earthquake. This paper introduces a potable earthquake simulator, called a Jishin-The-Vuton 3D, which realizes the up-and-down motion with the holonomic omni-directional motions in order to simulate three-dimensional ground motion of the earthquake. Focusing on the design concept, structure, and feature of this new simulator, the authors discuss its implementation and verify its feasibility with preliminary experimental results.

Manipulators, which are mounted on robots that substitute man at dangerous places like indoors and outdoors disaster sites or mine fields, have been mainly controlled by joysticks. However, joysticks are difficult to manipulate and complex tasks become hard to be done by operators because of a limit and discordance of controlled degree of freedom. Therefore, a controller with high operability like the Master-Slave system is needed, nevertheless conventional controllers are not used in these situations because there is no controller which has compact structures and intuitively controls 3DOF position and 3DOF posture. In this research, we propose a remote controller “Armrest Joystick” of the Master-Slave system which has high portability and operability. The Armrest Joystick is attached to a foldable portable chair and can be carried easily. It consists of a 3DOF position controller with an armrest supporting the operator's arm during operations, a 3DOF posture controller and a gripper controller. Furthermore, it has motors for the force feedback on all axes for more intuitive operations. In this paper, we report the basic concept and design of the Armrest Joystick, and the experiments which verify operability and the validity of the force feedback.

In the accident of nuclear disasters or biochemical terrors, there is the strong need for robots which can move around and collect information at the disaster site. The robot should have toughness and high mobility in a location of stairs and obstacles. In this study, we propose a brand new type of mobile base named “crank-wheel” suitable for such use. Crank-wheel consists of wheels and connecting coupler link named crank-leg. Crank-wheel makes simple and smooth wheeled motion on flat ground and automatically transforms to the walking motion on rugged terrain as the crank-legs starts to contact the surface of the rugged terrain and acts as legs. This mechanism features its simple, easiness to maintain water and dust proof structure, and limited danger of biting rubbles in the driving mechanism just as the case of tracked vehicles. Effectiveness of the Crank-wheel is confirmed by several driving experiments on debris, sand and bog.

A practical robot for search and rescue operation is demanded. We believe that one of the most promising robot is a snake-like robot with a slim and active trunk. This paper proposes a new multi-wheeled snake-like robot with active elastic trunk. We choose active wheels for the propulsive device due to mechanical robustness and simplicity, and increase locomotion capability by serially arranging many active wheels along to the trunk. We also propose a new mechanism for the trunk which satisfies both active bending motion and passive compliance. The active elastic trunk consists of deformable elastic segments made of sponge and rigid (or semi-rigid) segments, where active wheel is attached, stacked in layers. The active bending motion is generated by pulling the cables passing through the trunk from the head to tail. We develop three prototypes named “Souryu-VII”, “Souryu-VIII” and “Souryu-IX”. The mechanical design and features for each prototypes are explained and their performances are evaluated through the experiments with various measures.

Japan is planning to send a rover to the moon to investigate the moon surface in the near future. Therefore, considerable researches and developments about the subject are being done. We particularly have continued to propose expandable three-wheeled rovers, and to develop them. This paper proposes the new concept of the three-wheeled rover “Tri-Star IV” composed of three spring wheels and two rotating arms, and describes its mechanical design.

A free rigid body dynamics simulator “Open Dynamics Engine” is empirically compared with the results of hardware measurements in joint torque/power dimensions for a quadruped robot “TITAN-VIII”. We developed the quadruped robot model on the simulator and compared simulated joint torques and powers with hardware experiments during walking which takes four different walking postures. The results suggest that the direct acquisitions of simulated joint torques include a large latency in our application but this defect is avoidable by using joint force information. Careful parameter settings and tunings permit the simulator to match hardware experimental data with sufficient accuracy.

Roller-Walker is a leg-wheel hybrid mobile robot using a passive wheel equipped on the tip of each leg. The passive wheel can be transformed into sole mode by rotating ankle roll joint when Roller-Walker walks on rough terrain. This paper discusses energy efficiency of locomotion in wheeled mode. We define a leg trajectory to produce forward straight propulsion and discuss the relationships between the parameters of the leg trajectory and energy efficiency of the propulsion using numerical simulator. We find optimum parameter sets where optimization criteria is specific resistance. Then we carried out hardware experiments and empirically derived experimental specific resistance. We show that wheeled locomotion has 8 times higher energy efficiency than ordinary crawl gait. Finally we compare the specific resistance of Roller-Walker with other walking robots described in the literatures.

Falcon-III is a robotic personal vehicle that has been designed for uneven terrain usage. It has a two-degree-of-freedom suspension mechanism that allows the passenger's seat orientation (pitch and roll) to be controlled by actively adjusting the height of its wheels. This paper discusses the motion control of such a vehicle on rough terrain. In particular, we show that a feedback control law that measures the vehicle seat attitude and acts to correct it, aiming at maintaining the horizontal seat posture during the traversing of uneven terrain, is by itself insufficient to provide satisfactory performance on certain types of terrain. Therefore, we propose a predictive motion control strategy, in addition to the feedback control law, that dynamically controls the vehicle suspension in order to facilitate the negotiation of obstacles - the motion executed is somewhat similar to that performed by a cyclist when overcoming a step-like obstacle. When tall step-like obstacles have to be negotiated, it may be necessary to dynamically lift one of the wheels from the ground, in which case a gait pattern emerges.

There are many researches about mobile robot with a varied wheel. Mobile robots or mobilities with wheels such like a car or bike have non-holonomic constraint and then it is difficult to move toward wheel's axis direction. Namely, it is impossible to move toward omni-direction due to the constraints by wheel's mechanical structure. Omni-directional movement means the mobility can move toward any direction at anytime. This paper adapted link-driven spherical wheel as an omnidirectional wheel and solved singularity problem caused by mechanical structure of it. We developed omni-directional mobilities( SO(2) and SO(3)) installing link-driven spherical wheels and experimented omni-directional movement with designed controllers.

Home oxygen therapy (HOT) is a medical treatment for patients suffering from severe lung diseases. Although walking outdoors is recommended for patients to maintain physical strength, patients always have to carry a portable oxygen supplier which is not sufficiently light weight for this purpose. Our ultimate goal is to develop a mobile robot to carry an oxygen tank and follow a patient in an urban outdoor environment. We have proposed a mobile robot with a tether interface to detect the relative position of the foregoing patient. In this paper, we improve mobile platform mechanisms and active wheels to maximize the step height which can be negotiated, and to allocate sufficient space in the main body to carry an actual oxygen tank. The following control algorithm is also improved and its effectiveness is demonstrated in an outdoor experiment.

We propose a new weight compensation mechanism with a non-circular pulley and a spring. We show the basic principle and numerical design method to derive the shape of the non-circular pulley. After demonstration of the weight compensation for an inverted/ordinary pendulum system, we extend the same mechanism to a parallel five-bar linkage system, analyzing the required torques using transposed Jacobian matrices. Finally, we develop a three degree of freedom manipulator with relatively small output actuators and verified that the weight compensation mechanism significantly contributes to decrease static torques to keep the same posture within manipulator's work space.

With the appearance of many personal vehicles developed for urban environments, it seems pertinent to address the development of off-road personal vehicles as well. This paper discusses this exact topic, and proposes a three-wheeled configuration which stabilizes the horizontal posture of the vehicle's driver in rough terrain. The merits of such a machine are examined; in addition, a mechanism here called sliding-rod-end is introduced, and the reasons for its use instead of regular rod ends are explained. A full-scale prototype of the machine was built and is briefly presented.

In this paper, we discuss approximations to continuous curves of the Active Cord Mechanism (ACM) which is composed of arc-shaped joints or double joints. ACM is a machine which is made of a series of bending joints and forms a cord, and it has potential to work in challenging environment due to its large degree of freedom. In prior research most of ACM were composed of straight links and joints, and a lot of successful control methods for them have been proposed. However, the control of the ACM that is composed of arc-shaped joints or double joints has not been studied sufficiently so far. In this research we propose the method of approximations to continuous curves for such kind of ACM and use it for the control. The proposed idea is verified by numerical calculations and experiments by a robot.

This paper describes a development of a light duty arm with an active-fingertip gripper for handling discoid objects. The system is potentially capable of sharing the workspace with human workers, assuming the use in a cell manufacturing system. We propose a new 3-DOF gripper mechanism with two fingers which symmetrically move in parallel and each finger has a 2-DOF fingertip of a cylindrical shape. We also develop a lightweight arm with a weight compensation mechanism which is composed of a non-circular pulley and a spring to minimize required actuator torque. After verification of basic performance, the hand-arm system successfully performs a pick-and-place task for a discoid object from horizontal placement to vertical placement and vice versa. We demonstrate continuous 100 times pick-and-place operations without failure where its cycle time almost equals to a human worker.

We propose track-changeable quadruped walking robot, named “TITAN X”. TITAN X is a new leg-track hybrid mobile robot with a special leg driving system on each leg. A belt on each leg changes to a timing-belt in leg form and a track-belt in track form. TITAN X walks in leg form on rough terrain and makes tracked locomotion using track-belt on level or comparatively low-rough terrain. The characteristics of TITAN X are: 1) it has a hybrid function but is lightweight, 2) it has potential capabilities to demonstrate high-performance on highly-rough terrain. In this paper, details of leg design using a special belt are reported. Also form changing mechanisms are integrated into the system. We have constructed prototype of TITAN X to demonstrate basic performance. Experiments were conducted to verify the validity of the concept of track-changeable walking robot.

Many serious accidents are reported about the manual window cleaning task, and it is needed to automate the task for the majority of windows having no special guide frames for window cleaning machines. This paper proposes a novel tethered window cleaning robot named a “SkyScraper-I” and discusses its design. The SkyScraper-I has the functions to approach all the windows located on one side of a building by controlling the lengths of a pair of suspending tethers from the top of the building and to clean the whole surface of the windows. The robot consists of the vertically suspended sliding rod, a pair of clamping arms with clamping suction rollers on both ends, and a squeegee sliding mechanism to wipe the window. The clamping suction rollers have three functions: to fix the Sky-Scraper between the upper and lower frames of the window, to produce a suction force without touching the window, and to drive sideways for wiping all the window. From the several preliminary experiments, the SkyScraper-I demonstrated good mobility to move from window to window and to clean the surface of each window.

This paper discusses the design of a new snake-like robot without wheels, named ACM-R7. It has 18 DOFs, is 1.6 m in length and weighs 11.7 kg. It features a water-tight structure, a large motion range pitch joint of ±90 degree and a high output-power actuator arrangement, based on the coupled drive concept. Furthermore the control method “Loop Gait” is discussed. For this gait the ACM-R7 forms a loop shape and rolls like a wheel on the rim. We introduce the “Serpenoid Oval” for the loop shape. It s formed by a smooth sinusoidal angular motion of the joints. Moreover we consider the modification of the “Serpenoid Oval” for steering and obstacle avoidance. The performance is then verified by several motion experiments.

Foot mechanism of walking robots needs to adapt to rough terrain enough because the walking robot is requested to have the ability to walk stably on rugged ground. However, the foot mechanism of multi-leg walking robots have been often modeled as a point foot or a disc sole so far, and there is a problem that the robot can not fully use the sole area as a support polygon on rough terrain. To solve the problem, the terrain adaptive sole is developed which can adapt to the ground with small ruggedness and support the ankle moment to acquire stable footholds on uneven terrain. The terrain adaptive sole is composed of a deformation mechanism, a shape-fixing mechanism and a vertical force sensor, which are developed for quadruped walking robot TITAN VIII. The deformation mechanism changes the shape of the foot according to the terrain and the shape-fixing mechanism fixes the shape after the foot landing. These functions are achieved by a passive mechanism to be robust and lightweight. We demonstrate that TITAN VIII with the proposed terrain adaptive sole can successfully negotiate a rough terrain.

This work presents the development of an arm-equipped tracked vehicle named HELIOS IX for search and rescue tasks in urban environments. HELIOS IX operator has to tele-operate several tasks such as opening of doors, negotiation of stairs and handling objects. However due to the complexity and kinematics of the system, these tasks are difficult to be carried out without some level of automation. This study proposes one of the shared autonomy type operator-supporting system for HELIOS IX. It is based on a laser range finder (LRF), finger-attached LED beam guiding systems and on a finger 3 axes force sensor interfaced by a novel reinforcing metal plate. Carrying out several experiments we could demonstrate that, tele-operation task can become easier by the introduction of the 3D space approaching assistance of the LRF, object grasping assistance of the LED beams attached on the fingers, and by the force following assistance of the force sensor attached to the wrist.

A snake-like robot has an advantage in moving into a narrow space. Particularly “pedal wave”, which is one of its locomotion styles, is suitable for entering a thin path. However, pedal wave have been used only for going straight in most of the prior studies. In particular horizontal steering of pedal wave by a real robot has not been investigated sufficiently. Therefore in this paper we studied a kinematically appropriate steering method of pedal wave using a continuous snake-like robot model. We proposed steering by superposition of a steering curvatures and a pedal wave's curvature, and investigated the condition of suitable steering curvature using kinematic simulations. The proposed steering method was verified by experiments with a real snake-like robot.

Mobile platforms when negotiating steps and stairs should be able to control theirs posture in order to avoid sudden tilting or falls. In particular, when considering applications for search and rescue operations where users have a very limited time of operation, the motion on stairs should be automated as much as possible. In this way operators can concentrate on their tasks (i.e. search of survivors and/or exploration of dangerous environments) rather than having to focus on the stability of the vehicle. A simple but very effective mechanism called ldquotailrdquo is introduced. The mechanical design and its control method is presented together with several tests and experiments carried out with a simple tracked vehicle in real environments.

Now that mobile robots are getting tested more and more in challenging areas, difficulties in control, particularly when the robot cannot be seen, have appeared. In this research a mobile snake robot with actuated wheels is given the ability to sense its surroundings through its wheels by 3DOF force sensors, so that semi-autonomous control can be realized. This will simplify necessary operator commands and improve situation awareness through information feedback. Even with the many limitations of practical robot design, such as unwanted flexibilities, and measuring while actuating the wheels, the sensor's errors are confirmed to vary between just 1% and 3%. Moreover, sensitivity is equal over the wheels, only a 3s calibration at startup is needed, and the sensor is shown to be resistant to aging and temperature change. The sensor is implemented directly into a new snake robot, one sensor in each segment. Its central control will adjust the snake body according to the surroundings while automatically avoiding obstacles and crossing gaps.

The Active Cord Mechanism (ACM) such as a snake-like robot is suitable for tasks in a narrow environment because of its slender body, but mechanical models developed in prior research were somewhat large for practical usage. In this paper, we propose a new 2-dof joint mechanism for the small ACM. A usual joint mechanism has the same number of rotational axes as that of the actuators, but the proposed mechanism has 4 rotation axes against 2 actuators. This joint mechanism has relatively large range of motion and it can improve the capability of ACM in a narrow environment. We verified the specification of the proposed mechanism and the result showed that it is suitable for the small ACM. In addition, we developed the ACM with the proposed joint mechanism, and it realized a sidewinding motion, which is a kind of snakes' locomotion style. We think this result shows that the proposed mechanism will contribute to the study of the small ACM.

Fire brigades and special agencies are often demanded to operate for search and aid of human lives in extremely dangerous scenarios. It is very important to first verify the safety of the environment and to obtain remotely a clear image of the scenario inside buildings or underground spaces. Several studies have been addressing the possibility of using robotic tools to carry out safe operations. This contribution presents the development of the HELIOS team, consisting of five tracked robots for urban search and rescue. Two units are equipped with manipulators for the accomplishment of particular tasks, such as the handling of objects and opening doors; the other three units, equipped with cameras and laser range finders, are utilized to create virtual 3D maps of the explored environment. The three units can move autonomously while collecting the data by using a collaborative positioning system (CPS). After an overview on the specifications of the team of robots and with respect to previous publications, detailed information about the improvements of the robot mechanical design and control systems are introduced. Tests of the CPS system and HELIOS IX vehicle together with a typical mission experiment are presented and discussed.

For the purpose of detecting CO2leaks during ocean CO2sequestration, there is a need for independent underwater robots that can make observations while maintaining their position over the seabed against the current for long periods of time. In order to achieve this objective, a novel tether mooring type underwater robot was proposed. The robot is moored and its position is controlled by changing the length of the tether. In addition, it can sustain itself with a sea current power generation system. After that, the prototype underwater robot ¿Anchor Diver¿ was developed. Anchor Diver is moored by one tether, moves using horizontal and vertical rudders and moves upstream by reel mechanism. In addition, the use of a movable anchor and generator as a propeller enables Anchor Diver to enlarge its range of activity. This paper describes the detailed development of Anchor Diver and underwater experiments.

We proposed new arm-wheel hybrid robot "Souki-II" which consists of a body, a pair of large bore wheels which sandwich the body and rotates around the same axis from the body, articulated hand attached to the body, and free caster attached around the wrist of the hand. Souki-II showed high terrain adaptive motion by using the large bore wheels and free caster of the hand. We also showed that the mobility can be enhanced when multiple units are connected together. Souki-II can also take the mode of a manipulator. For the joint mechanism of the Souki-II, we introduced a unit actuator system and a cover member with spiral groove to pass the electric harness and to assist in heat dissipation. From the experiments of the constructed models, we could demonstrate the innovative performance of the proposed Souki-II system.

The inspection of high-voltage transmission lines is a dangerous and time-consuming job, that relies on especially trained workers operating tens of meters above the ground, and close to live lines with thousands of volts. This paper presents the development of a tele-operated robot designed for preventive maintenance of high-voltage lines. The robot was designed with mobility in mind, so that cable spacers, suspension clamps and other obstacles, which so far have prevented the use of robots for inspection of high-voltage lines, would not hamper the operation of the machine. After careful considerations on mobility, the robot was designed, and a prototype was built. Results of tests, performed on facilities reproducing real field conditions, are also presented in this paper.

High mobility and large payload capability are important abilities for wall climbing robots. The authors have proposed a new robot system Anchor Climber that could achieve both of these abilities. This robot system is composed of two or more child units and a parent unit. As child units of Anchor Climber, the authors have developed three types of special wall climbing robots, Adhering Mobile Units (AM Units) Type A, B and C. In this paper, developments of other components of Anchor Climber, configuration of Anchor Climber with these components, basic systematic experiments with configured Anchor Climber, and new type of AM Unit are described. From results of the experiments, it was confirmed that Anchor Climber had both high mobility and large payload capability.

There have been several works proposing mobile robots for inspection of high-voltage transmission lines. Those studies addressed mostly locomotion issues, with little attention paid to the sensing task. However, the deployment of sensors around the cables is not an elementary operation. This work indicates which sensors may be most suitable for the inspection of transmission lines, and describes their assembly in a simple and compact structure (Sensor-Unit). In addition, it proposes several manipulator mechanisms (Sensor-Arm) to deploy sensors around the cables and to remove them when necessary. The mechanisms are compared taking into account practical aspects such as assembly, reliability, functionality and results of field experiments. Finally, the design of a high-quality camera for detailed inspection is also described.

Roller-walker is a leg-wheel hybrid mobile robot using a passive wheel equipped on the tip of each leg. The passive wheel can be transformed into sole mode by rotating ankle roll joints when roller-walker walks on rough terrain. This paper describes adaptation of characteristics of the propulsion by a leg trajectory in the case of wheeled locomotion. Firstly, the authors demonstrate that Roller-Walker could achieve high-speed propulsion and slope climbing propulsion by simply changing parameters of the leg trajectory on the hardware experiments. Secondly, an asymptotic parameter tuning method is introduced to perform specified velocity on the different surfaces with different friction. The method is evaluated in numerical simulations. The results suggest that the method allows the Roller-Walker to have a function similar to an automatic transmission of a usual car.

Fire brigades and special rescue agencies are often demanded to operate for search and aid of human lives in extremely dangerous scenarios. The use of robotic tools can make those operations safer for the operators and more efficient in terms of time and allocation of resources. This contribution describes the development of the newest tracked vehicle HELIOS IX. This mobile platform equipped with a manipulator represents the first stage of a Japanese national founded project. It aims to the development of a robotic system to be utilized in extreme environments such as rescue operations in heavily stricken urban areas. With respect to the previous prototypes the mechanical design and the system architecture is described. A new gripper is also introduced and tested together with few mobility experiments of the platform.

High mobility and large payload capability are important for wall climbing robots. The authors have proposed a new robot system Anchor Climber that could achieve both of these two abilities. This robot system is composed of two or more child units and a parent unit. As child units, wall climbing robots Adhering Mobile Units (AM Units) have been developed by using the technique of internally-balanced magnet (IB Magnet). In this paper, study of IB Magnet to use AM Units effectively, proposal of transformable crawler unit as a driving unit of AM Unit, development of an advanced AM Unit with these new mechanisms, and experiments with the robot to confirm effects of added new mechanisms are described.

This paper proposes a new leg-wheel hybrid jumping robot ldquoAirHopperrdquo. AirHopper is expected to overcome uneven terrain, which is difficult to move around for ordinary vehicles which carry supplies for disaster areas or isolated districts. To acquire high mobility and jumping, AirHopper consists of the following mechanisms. 1) 4 legs that are widely spread like a spider for stability, 2) active wheels on its feet which are driven by built-in motors and transmissions, 3) 2 decoupled pneumatic cylinders per leg and a built-in piston that drive 4-bar linkage leg mechanism. In this paper, we proposed the design of a powerful light weight leg-wheel mechanism, and verified its validity. AirHopper jumped 850 mm vertically, and landed on the ground softly by means of controlling in-cylinder pressure. Running jump motion was also achieved.

Slim slime robot (SSR), that looks like an active cord mechanism (snake like robot) and is composed by units that can stretch, shrink and bend actively, is meant to be used for several tasks in narrow spaces such as moving under collapsed houses or for inspection of pipelines in plants. We propose a new concept named "bridle drive", that was developed from the prototype model of the units of the SSR-2.3 that has units of the bridle bellows composed of a large caliber bellows and wire lock systems. The use of the bellows allows to produce a high output using air pressure, and its shape can be changed by controlling the length of the wires. In this paper, to solve problems of the previous model of the bridle bellows, we modified its brake systems and propose a new control method named PCBS.

Robotics research can help search and rescue operations with developing practical mobile platforms and tools for urban and industrial disaster response. Crawled vehicles, because of their terrain adaptability, have a considerable importance for rescue operations and tasks performed in unstructured environments. In this contribution we present the newest version of HELIOS robot (HELIOS VIII). It consists of the same mechanical concept introduced with its predecessor. Nevertheless all the efficient motion capabilities of HELIOS concept were maintained and improved. In this paper we will focus a lot on the development of a new gripper for HELIOS vehicle. It consists of four fingers actuated by one actuator and they can adapt to the grasped object surface. Besides we introduce also a special docking mechanism utilized for the connection of the vehicle with auxiliary crawler units.

High mobility and large payload capability are important abilities for wall climbing robots. Authors have proposed a new robot system can provide both of these abilities, named anchor climber. This robot system is composed of two or more child units and a parent unit. Authors also have proposed special wall climbing robots to use these robots as child units of anchor climber, named adhering mobile units (AM Units). Moreover, authors have already developed AM Unit Type A as first prototype of AM Unit. In this paper, authors describe developments of two new types of AM Units, a new type of cover mechanism, and experiments with these AM Units. For these experiments, authors confirmed these units had abilities to act as child units of anchor climber.

In this paper, we discuss about stabilization of the head of a snake-like robot. In prior research snake-like robots usually shook the head during undulating motion. However, a snake-like robot is usually equipped with a camera on the head, so the swing of the head is problem. To solve this problem, we propose a control method to stabilize the head of an undulating snake-like robot. In the proposed method, the motion of the neck is controlled to cancel the undulation of the body in order to stabilize the head. In this study, first we derived the formulas for this method, and confirmed the effectiveness by simulation. Then we implemented that control on a real snake-like robot and showed the availability of the proposed method.

Manipulator operations are complicated by sensor noise, mechanical compliance, and system bias. These uncertainties are compounded in field environments, such as those encountered in humanitarian demining. By taking advantage of the generally flat and static structure of the terrain, a series of adaptive corrections and filters refine a sensed topographical model and generate a trajectory that is robust to inherent inaccuracies and modeling errors. Experimental testing on a mobile robot using stereo-vision as modeling sensor indicates that this method provides a tracking precision of plusmn5 mm on relatively flat ground. As such, it will keep the attached mine sensors close to the ground, improving effectiveness

This paper proposes a new mechanism and control method of 4-leg-wheel hybrid locomotion. Many previous hybrid vehicles execute wheel-mode and leg-mode alternatively. However, to overcome higher obstacle with sufficient velocity, a wheel locomotion should continuously be executed. In this paper, suitable load distribution control is proposed considering a contact force to the ground and step edge, a wheel driving torque, and a friction coefficient of the wheel and terrain. In a proposed new leg-wheel hybrid mechanism, load distribution control is realized by a torque of twisting joint at the center of the body, and a forward/backward shift of the body. The validity of this control and mechanism is confirmed by some experiments, where vehicle can run over a 105 mm step by 90 mm radius wheels with a good continuous movement. With an adjustment control of the approach angle, a robot can also ride over a 230 mm step

Snake-like robots and hyper-redundant manipulators have been called active cord mechanism (ACM), and they have been one of fields of robotics. However, general study on the spatial shape of ACM has not been conducted enough so far. In this paper, we propose a effective method for analysis of the 3D shape of ideal continuous ACM models. In addition, we show some important characteristics of ACM using this method. The results help us understand the characteristics and possibility of ACM

The expandable-type rover, which retracts in the spaceship and expands after reaching upon landing seems to be effective as the planetary rover. In our laboratory, "Tri-Star3"; a horizontal poly-articulated expandable 3-wheeled planetary rover based on the expandable rover has been developed. Tri-Star3 has just only three wheels and passive joints with braking mechanisms. This rover expands or changes its own shape by the driving force produced by each wheel when the joints are free to rotate. Because of these reasons, this rover is comparatively light-weight is cheap to manufacture and it is easy to operated.

In this paper, a horizontal polyarticular expandable 3-wheeled planetary rover "Tri-Star3" is proposed. This expandable rover conjugates compact folded size with high stability on rough terrain. The design of braking mechanism in each arm's joint is explained in detail. Through experiments, we confirmed the effectiveness of: (i) the underactuated braking mechanism with optimal shape cam and (ii) the underactuated motion of the arm-wheel module. By using this the proposed system achieves omnidirectional mobility with light weight

This paper presents a quadruped-walking robot for demining mission. Robot that can adapt any landscape and handle various tasks by utilizing the legs as manipulator is useful one to ensure the safety of local residents and people engaged in the demining mission. However, it is known that mine removing by human workers is progressing slowly because of the risk of their lives. The proposed robot has various features, such as 1) much wider working area than conventional walking robots, 2) unique drive mechanism, 3) high modularity and cooling mechanism and so on. It is expected to give the workers safety to accelerate the demining.

For large robots, the decrease in position accuracy that comes from compliance of the robot system poses significant problems. We propose a new compensation method to improve position accuracy of leg mechanisms of walking robots. With this method, compliance data that is measured manually in advance is used. At present, TITAN XI - a practical quadruped robot for use in construction - is under development, and this compensation method is being applied to its control system. In this paper, the measurement of the compliance of the leg system using a hydraulic cylinder, the bending of the legs in walking motion, and the walking motion with compensation are shown.

A reconfigurable planetary rover system (RPRS) is presented, including the parent body and some child robots. The child robot composed with the arm part and the wheel part has two moving modes: locomotion mode and manipulation mode. According to the mechanical characteristics, we proposed the two methods for the motion planning of swerving locomotion. The results of experiments showed that the robot can achieve turn during locomotion by adjusting the arm's attitude. But the child robot's radius of left-hand turning motion during locomotion is bigger much than the radius of right-hand turning motion during locomotion and the effect is not obvious. The method of spot turning is presented by use of the difference between radial frictional force and tangential frictional force of ground and direction wheel, which is important for robot for autonomous locomotion.

High mobility and large payload capabilities are important features for wall climbing robots. However, traditional designs could only provide one or other but not both of these features at the same time. In this paper, we propose a new robot system named "Anchor Climber", which can provide both high mobility and large payload capabilities. The proposed system is composed of two or more mobile units which can stick firmly to the wall when in a stand-still state, and also freely and reliably move on the wall holding enough adhering force to not fall from the wall during the moving state. We call this kind of unit as "adhering mobile unit". This paper address in detail, the necessary conditions to configure such a system, and also introduces the development of an adhering mobile unit using permanent magnet.

"VmaxCarrier2" is an omni-directional mobile robot with step-climbing capability, which can be used as a compact, quiet, and durable transportation vehicle in cluttered and cramped environments. In this study ,we discuss the step-climbing sequence of this omni-directional mobile robot with step-climbing capability. In addition that, we show some motions on steps and slope of this vehicle.

Leg-wheel hybrid mobile vehicle has been regarded as the best combination and many of them have been presented recently because of the high terrain adaptability of legged walking robots on rough ground and the high mobility of wheeled mobile vehicles on flat terrain. We discuss the detailed actualization of safe and stable stair climbing and three-dimensional locomotion for wheelchair - with mainly indoor or ordered terrain environments - in mechanism sensor system and control method based on the developed leg-wheel hybrid mobile vehicle Zero Carrier I in this paper.

Slim slime robot (SSR), looks like an active cord mechanism (the snake-like robot) and composes units that can stretch, shrink and bend actively, is for several tasks in narrow spaces such as to move under collapsed houses or for inspection of pipelines in plants. In this paper, we propose the new concept, which is named "bridle drive". We developed the prototype model of the units of the SSR-2.3. Each unit has a bridle bellows composed of a large caliber bellows and wire lock system. The use of bridle bellows allows to produce a high output using air pressure, its shape can be changed by controlling the length of the wires.

A considerable number of landmines and unexploded ordnance (UXO) are buried in many disaster-affected countries. Although some methods to remove them have been proposed, there are still many problems. We propose new mechanical master slave hands to remove landmines and UXOs. At first, we have made a test model. We have conducted hearing about the first model with expert deminer of Afghanistan. Then we made improved model. Through several basic experiments, the second model is estimated to be practical.

The snake-like robots of the 'Genbu' series (Genbu 1,2,3) consist of multiple modules, equipped with active wheels, connected to each other by passive joints. These robots are categorized as Active-Wheel Passive-Joint articulated mobile robots (AW-PJ type). AW-PJ type robots have high-speed mobility and high-durability on rough terrain in spite of several problems, such as stuck condition, due to the passive joints. These are good proper-ties for fire-fighting robots or planetary rovers. Genbu 3, developed in this study, could climb a 280mm vertical wall whereas the diameter of the wheel is 250mm. This paper de-scribes automatic stuck detection algorithm and stuck avoidance methods. Para-skid steering is also described. Results of experiments with Genbu 3 are presented and discussed in order to verify these methods.

"VmaxCarrier2" is an omni-directional mobile robot with step-climbing capability, which can be used as a compact, quiet, and durable transportation vehicle in cluttered and cramped environments. We have already developed several kinds of omni-directional mobile robots for situations where it is desirable to be able to move in all directions, such as "VUTON" and "VmaxCarrier". To construct an omni-directional mobile robot with a greatly improved capability to climb steps, we developed the Omni-Disc2, a bent pneumatic actuator, and a pneumatic system. These novel components were constructed into a prototype, and through evaluation experiments we have confirmed the improved step climbing capability of VmaxCarrier2.

This research aims to build a practical mobile robotic system to be used in actual humanitarian demining tasks. The basic system consists of a manipulator mounted on top of a mobile platform. For the purpose of building a practical and versatile mobile platform, the authors have already developed a 4-wheel autonomous buggy system called "Gryphon", as discussed in previous works. This paper addresses the development of an energy-efficient weight-compensated manipulator, which is composed of a 5-node parallel linkage. The manipulator was especially designed for antipersonnel mine detection and removal tasks. The weight-compensation concept and the principle of operation are discussed in detail, and the validity and usefulness of the manipulator, as well as of the whole robotic system, are demonstrated by real experiments.

We have developed Souryu-I and II, connected crawler vehicles that travel in the rubble. They were developed for the purpose of finding survivors trapped in collapsed buildings. We have identified problems of these machines through experiments and studies, which are shape of the crawler, joint mechanism, dust- and waterproofing and communication system. We developed an improved model called Souryu-III based on these findings. It has unitized crawlers, new joint mechanism, dust proofing and waterproofing mechanism and tethered communication system with a new reel mechanism in order to address those problems. This paper describes Souryu-III, its mechanism and the experiments to test its mobile performance.

In this research an arm-equipped vehicle for search and rescue operations is presented. The important features for tracked vehicles are introduced through an overview of the solutions so far developed. The concept and the motion capabilities of the new vehicle Helios VII are explained. Afterwards the first assembled prototype is validated by means of mechanical computer simulations and basic experiments on the real vehicle.

There are many dangerous and time-consuming construction works performed on steep slopes. In order to improve the conditions in which these works are done, the authors propose a new construction machine that is a quadruped walking robot called TITAN XI. The main objective of remote-controlled TITAN XI system is to drill the deep holes for insertion of anchor bolts or rock bolts. In this paper, we report the system and design of TITAN XI.

To accomplish high mobility and working performance, an active ankle mechanism with multi-degrees of freedom is required for multi-legged walking vehicle. In this paper, a novel active ankle mechanism with 2 degrees of freedom is proposed. This mechanism has large workspace, high mechanical strength and coupled driving system.

In this paper, the wire-driven weight-compensation mechanism is proposed. This mechanism consists of a parallelogram linkage mechanism that has an extended portion with the wired double pulley. This is a lighter solution compared to others since no springs are utilized. Below, a detailed description of this new weight-compensation mechanism and performances of Float Arm V with this new mechanism are given.

We propose a new planetary rover system called "SMC-Rover". This system consists of one main body and some detachable units, which can work as child rover, and also become driving units of the main body. Each detachable unit, consisting of a single manipulator mounted on a wheel, is called "Uni-Rover". This paper discusses a new method of trajectory modelling and steering control optimization for the Uni-Rover, using the relation between arm posture and turning radius. The validity of the presented method is verified by computer simulations and experiments with an actual mechanical model. Thus, effective arm-posture-based steering method is introduced.

At present, robots are demanded not only for stationary use but also for tasks that require high mobility. The important abilities for such robots are both moving and task performing abilities. However, in order to perform tasks and move using separate mechanisms, robots are required to have many degrees of freedom (DOF). As a result, robots become heavy and lose mobility. In this paper, an effective design of robots with reduced-DOF is described. Besides, an 8-DOF bipedal configuration robot with high tasking and moving performance was developed. In this robot, the DOF have been reduced as much as possible without hampering its mobility, finding a balance between the increase in weight with additional DOF and the loss of manipulability with reduction of DOF. Moreover, applying this concept to the locomotion using the same DOF for differential purpose, it is possible to use the sane mechanism for the legged locomotion and wheeled locomotion. In this paper, this concept and maneuvers for locomotion are described. New experimental model is designed and experiment results for proposed locomotive maneuvers are expressed.

In this paper, the fundamental concepts of the dinosaur-like robot called TITRUS and the mechanism design of the miniature prototype robot TITRUS-III are mentioned. TITRUS is based on the concept to realize a practical mobile working platform. Its advantages are described on the discussion with two models: the rigid body system and particle system. The features of TITRUS are: 1) realizing high dynamic stability by using the neck and tail as an active dumper when the robot walks; 2) standing with the tail to compose a stable supporting triangle so that the robot can work stably; and 3) enabling it to do various tasks by applying a manipulator to the neck. Finally, the fundamental walking experiments to examine usability of the neck and tail on TITRUS-III are reported.

Landmines represent a clear threat to the civilian population in war-ravaged countries, and hamper peacekeeping and reconstruction efforts. The seriousness of this issue demands immediate automation of the mine detection and removal tasks, but until now only partial mechanization has been available. This paper proposes a versatile and feasible automated system based on mobile platforms to improve humanitarian demining, taking into account field requirements. Details of the development of the mobile platforms are presented, as well as experimental results. Special tools and components, also briefly described, are under development in order to maximize the range of applications of this system.

This paper proposes a new walking and jumping robot, that is expected to get over large debris in the disaster area which is difficult to move around by ordinary walking robot and to find out the victims efficiently as the rescue operation. To acquire stability on uneven terrain in landing, the robot is designed by legs which widely spread like spiders. The legs are consists of 4-bar linkage and driven by a pair of pneumatic cylinders which momentarily produce high power and speed. At this time, basic performance of the pneumatic cylinder is verified for the jumping use. Moreover the one leg model is developed and examined its jumping and landing performances.

This paper introduces a novel Shape Feedback Master Slave (M-S) arm system, which is inexpensive and robust to be equipped in the demining robot "TITAN-IX". A M-S arm system is an important element. However, it is very difficult to use the conventional M-S arm system into unpredictable environments such as a minefield, because the control parameters to adapt the environment are mostly unknown. The newly introduced Shape Feedback M-S Gripper (SPADE GRIPPER) for detecting and removing mines is composed of three unilateral position controls without bilateral force control, can work stably in such an unknown environment. The mechanical design and the operation principle of SPADE GRIPPER and several experiments are performed to examine its validities.

In this paper, the motion using the dynamic effect of the neck and tail of the dinosaur-like robot called TITRUS is mentioned. TITRUS is based on the concept to realize a practical mobile working platform. The features of TITRUS are 1) realizing high dynamic stability by using the neck and tail as an active dumper when the robot walks, 2) standing with the tail to compose a stable supporting triangle so that the robot can work stably and 3) enabling it to do various tasks by applying a manipulator to the neck. Finally, the experiments with numerical model and physical model TITRUS-III are reported.

This paper introduces a new concept in snake like robots, namely the Slim Slime Robot 2 (SSR-II), which has an added degree of freedom to stretch the body segment. The active cord mechanism (snake like robot) is capable of performing several tasks in narrow spaces, such as moving under collapsed houses, and inspection of pipelines at plants. Conventional snake robot mechanisms are designed as a series of connected articulated segments that have two degrees of freedom each. The SSR-II, with Bridle Bellows units composed of a large caliber bellows and a wire lock system, is explained. Bridle Bellows is an example of the "Bridle drive" which is introduced in this paper. The Bridle Bellows are able to change shape by controlling wire length and air pressure and produce large power. Therefore, from the experiment, SSR-II is shown to be effective for moving mechanisms at rough forging, which can transfer several locomotion forms.

The demand for mobile robots for hazardous field tasks, such as rescue operations in disaster scenes or landmine detection and removal has been increasing in recent years. Since electrical infrastructure is seldom available in such situations, robots that rely on chemical batteries or/and tethered connections to external electric generators suffer severe limitations in operation time and mobility. A different approach is being sought in this research, which involves the use of a combustion engine for on-board electric generation. For practical purposes, the authors used a commercial 4-wheel buggy as the base platform. Some mechanical adaptations in the steering, throttle, gearshift and brake mechanisms were performed, and the developed mobile platform (Gryphon-I) can be computer controlled. This paper introduces new strategies for the control of Gryphon-I over uneven terrain, and the effectiveness of the proposed methods is evaluated experimentally.

Snake-like robots have good properties to move on rough terrain. Their low-height bodies and articulated structures are proper to go into narrow space and to climb over obstacles. Thus, many applications of articulated mobile robots are expected (e.g. rescue robots). One of the types of snake-like robots named 'Genbu' consists of active wheels and passive jointed multi bodies. We classified this type of snake-like robots as active wheel passive joint articulated mobile robot. Although Genbu cannot go over wide gaps, they have high durability because their joints are not activated with gear-head motors. So, Genbu has high mobility on rough terrain at high-speed. Moreover the long articulated structure is proper to climb over obstacles because of size effect. For example, Genbu 2 equipped with 220mm diameter wheels can climb 300mm vertical wall. These characteristics are proper to use as rescue robots or planetary rovers. However these applications require semi-autonomous robots because the operator cannot approach the robots. The control method of this type of snake-like robots has not been established yet. In order to establish the control method, detecting the posture of the robot is very important. Nevertheless, Genbu 2 was difficult to detect the posture because of the elastic body join is. In addition, Genbu 2 had some problems for practical use (e.g. motor drivers are not inside). In this study, Genbu 3 was newly developed to solve these problems. In order to accomplish these purposes, the passive rigid joints for detecting the posture, and torque sensor with float differential mechanism are newly developed for Genbu 3. In this paper the mechanism of Genbu 3 and basic running experiments of Genbu 3 are described.

This paper describes the development and experiments of ACM-R3, which is a new version of the Active Cord Mechanism with three-dimensional mobility. This ACM-R3 is equipped with large passive wheels that wrap its body overall, and has frictional characteristics similar to snake-like skin. It is also equipped with radio control servomotors with gears added to them, held tightly by shell frames, so that it can move steadily and with high power With this robot, we realized fundamental two-dimensional serpentine locomotion, lateral rolling locomotion in "V", "U", or especially "S" shapes, and coupled locomotion, which employs both serpentine and lateral rolling at the same time. We also realized sinus-lifting locomotion, its mixture mode, 3D lateral rolling, and pedal wave.

In order to perform tasks and move using separate mechanisms, robots are required to have many degrees of freedom (DOF). If robots can perform both wheeled locomotion on flat ground and legged locomotion on uneven terrain, they can achieve much higher mobility. We have already proposed an effective design method with both mobility and manipulability, that is a method of combining each mechanism. The designed robot uses the same mechanism for locomotion and manipulation. By applying this concept to locomotion, it is possible to use the same mechanism for legged locomotion and wheeled locomotion. In this paper, this concept and maneuvers for locomotion are described and an experimental model and experiment results are reported.

There is the possibility to generate a very efficient locomotion strategy for a snake-like robot by introducing full-body helical motion. This paper proposes a new kind of propulsion principle for the underwater active cord mechanism, in which the helical motion is created by distortion of each articulated body segment, while keeping the whole body helically. This paper also discusses about the design of a new mechanical prototype to realize a hermetic underwater 3D active cord mechanism, used to verify the effectiveness of the newly proposed propulsion principle.

In this paper the fundamental concepts of the dinosaur-like robot called TITRUS and the mechanism design of the miniature prototype robot TITRUS-III are explained. TITRUS is based on the concept to realize a practical mobile working platform. ne explanation addresses its availability with two physical models: a particle system and a rigid body system The features of TITRUS are (1) realizing high dynamic stability by using a neck and a tail as an active dumper when the robot walks, (2) standing with the tail to compose a stable supporting triangle so that the robot can work stably and (3) enabling it to do various tasks by applying a manipulator to the neck. Finally, the fundamental walking experiments to examine usability of the neck and tail on TITRUS-III are reported.

We focus on the "Vuton-II", a new omnidirectional vehicle developed as a transport vehicle to operate within factories, hospitals, and warehouses. This vehicle is composed of three or more "Omni-Discs". The Omni-Disc mechanism ensures that individual wheels of the Omni-Disc assembly are always aligned in the same direction, and can always roll freely. The Vuton-II was based on the Vuton-I, an earlier omnidirectional vehicle with similar targeted use and controls characteristics. The Vuton-II is designed to be low in cost, short in stature, and reasonably high in payload.

Some stability criteria for walking vehicles on rough terrain are discussed. Several criteria for stability margin have been proposed previously and they can be roughly divided into three categories. The paper compares them with each other and concludes that a stability criterion based on energy consideration is the most reasonable for practical use through simple experiments. The existing stability margin is apparently inadequate because it varies with weight of the vehicle with the same posture, while weight doesn't affect its resistance to a tumble. Therefore, an improved stability margin normalized by weight is proposed. At the same time, a helpful tool to derive the desirable posture for walking vehicles is described which can maximize the proposed stability margin on rough terrain.

This paper describes a new fluid motor named "Crown Motor". It uses a new mechanism that consists of two crown gears with more than three cylinders around the rotation axis. The torque of this motor is high, with a high gear ratio of 77:1, accomplished by using only two crown gears, while rotation speed is slow enough (/spl sim/16 rpm) to allow for mobile robotic applications. The Crown Motor has been developed for the new fire fighter robot "Genbu" under construction in our laboratory. It has many advanced properties to be used in many applications: 1) it can drive with a low-pressure fluid (0.2/spl sim/0.7 MPa), like tap water (/spl sim/0.2 MPa); 2) it is able to control its torque and rotation speed independently when the supplied pressure of fluid is constant; and 3) it is easy to apply the motor to many kinds of machines such as used under (near) water or any kind of fluid. The electric and mechanical valve systems used are also described.

We propose a new trajectory planning for the stable trot gait, named 3D sway compensation trajectory, and show that this trajectory has lower energy consumption than the conventional sway trajectory proposed previously by Yoneda et al. (1995). As the adaptive attitude control method was used during the 2-leg supporting phase of the trot gait, we consider four methods: 1) rotation of body along the diagonal line between supporting feet; 2) translation of body along the perpendicular line between supporting feet; 3) vertical swing motion of recovering legs; and 4) horizontal swing motion of recovering legs. The stabilization efficiency of each method was verified through computer simulation and the damping experiment using a quadruped walking robot, TITAN-VIII. Furthermore, the dynamic trot gait control that combines the feedforward control based on the proposed 3D sway compensation trajectory and the adaptive feedback control using body translation and vertical motion of swing legs was developed, and the walking experiment on rough terrain using TITAN-VIII was carried out.

Currently, most of the robotic systems use electric actuators and depend on chemical batteries as source of energy. However, this results in severe limitations to their range and time of autonomous operation, making it difficult to employ those robotic systems in remote areas or fields. In order to solve this problem, the authors have developed a mobile platform with energy-generation capability and mechanisms to drive it automatically. In this paper, a new autonomous control for the mobile platform is proposed, including telemetry features, especially focused on hyper-tether applications Those applications may include landmine detection/removal and forestry works in environments where the currently available systems cannot operate uninterruptedly for long periods of time.

A continuously variable transmission (CVT) can be advantageously used to drive a robot in its most efficient operation region for a wide range of external loads. The paper describes an optimal load-sensitive control algorithm for an actuator unit comprising a CVT and an electric motor. The introduced control algorithm takes into account both the electrical motor and the CVT efficiency. The validity of the proposed method is demonstrated by simulations and experiments carried out on an actual stair-climbing mobile robot "HELIOS-VI".

We are developing the "HELIOS" series, platforms for off-road vehicles and powered wheelchairs that are able to ascend and descend stairs. At present, we are developing an endless rotation locomotion type terrain adaptive vehicle "HELIOS-VI" that is propelled by 2 crawler belts. This vehicle has two continuously variable transmissions to change the velocity and direction of locomotion. The vehicle also has two active arms attached to the axis of the one drive pulley of the active crawler. One of the arms has two passive tires installed at its tip, and improves the vehicle's terrain adaptability in rough terrain; the other arm carries payload and adjusts payload posture. We introduced a structure that can change the posture of this load dynamically. This paper first outlines development process of the HELIOS series, and then discusses the configuration of terrain adaptive crawler vehicle HELIOS-VI and the design of its driving mechanism.

We have already proposed a new planetary rover system called "SMC rover". This system consists of one main body and some wheel units, which are detachable and able to work as child rovers called "arm equipped single wheel rovers". A trial model of "small arm equipped single wheel rover" has already been designed and developed. In this paper, we explain the mechanisms of this rover, and also the results of basic experiments of locomotion and manipulation.

This paper describes the development of ACM-R3, which is a new version of the active cord mechanism with three-dimensional mobility. This ACM-R3 is equipped with large passive wheels which wrap its overall body, and has frictional characteristic as snake-like skin. It is also equipped with radio controlled servomotors with some gears added to them, and held tightly by shell flames so that it can move steadily and with high power. Each unit of ACM-R3 consists of a very simple structure, batteries, and electronic circuits to control itself. Consequently, ACM-R3 consists of as many units as we want to use, and is suitable for the platform of snake-like robotics researchers. ACM-R3 can demonstrate new propulsion methods and motions, combining the ability of a manipulator and a propulsion unit.

Multi-DOF flexibly-deformable machines are studied from. a biomechanical standpoint and are called "slime robots". A rope-like, one-dimensional slime robot called "slim slime robot" is paid special attention, and its mechanical design and basic locomotion are examined by experiments of the practical model.

In order to perform tasks and move using separate mechanisms, robots are required to have many degrees of freedom (DOF). As a result, robots become heavy and lose their mobility. In this paper, an effective design of robots with reduced DOF is described. An 8-DOF bipedal configuration robot with high tasking and moving performance was developed. In this robot, the DOF are reduced as much as possible without hampering the its mobility, by finding a balance between the increase in weight with additional DOF and the loss of manipulability with a reduction of DOF.

The fundamental concepts of the dinosaur-like robot called TITRUS and the mechanism design of TITRUS-IIII are reported. It is based on practical concepts so that it can be applied in the real world. The walking robot has become one of the most attractive themes in robotics. So far the issue has been how we could realize it. This means that the main theme has been how to make it walk However since the biped robot called P-II appeared, the paradigm has been changing into what the application will be. TITRUS-III is based on the concept to realize a practical application. The features are (1) realizing high dynamic stability by using a neck and a. tail as an active damper when the robot walks, (2) standing with the tail to compose a stable supporting triangle so that the robot can work stably and (3) enabling it to do various tasks by applying a manipulator as a neck. The mechanism of the legs is also distinctive, using a coupled drive to compose four degrees of freedom.

We have proposed a leg-wheel hybrid mobile robot named "Roller-Walker". Roller-Walker is a vehicle with a special foot mechanism, which changes to a sole in walking mode and a passive wheel in skating mode. On rugged terrain the vehicle walks in leg mode, and on level or comparatively smooth terrain the vehicle makes wheeled locomotion by roller-skating using the passive wheels. The characteristics of Roller-Walker are: (1) it has a hybrid function but is lightweight, (2) it has the potential capability to exhibit high terrain adaptability in skating mode if the control method for roller-walking is fully investigated in the future. In the paper, the 4 leg trajectory of straight roller-walk is optimized in order to achieve maximum constant velocity. Also a steering roller-walk control method is proposed. It is obtained by the expansion of the straight roller-walk trajectory theory adding an offset to the swinging motion. This steering method resembles that of a car. The control system was modified into an untethered system, and control experiments were performed. The realization of the steering motion was verified by them.

This paper introduces a new research on tethered connections called "hyper-tether", to provide tethering among different mobile robot types, such as a robot with the environment and a robot with humans and animals. Hyper-tether's basic function is to actively control the tether's tension and/or length, but it also considers tether launching, anchoring, power delivery, data communication cabling and built-in trajectory command generation capabilities. In this paper, the implementation details, advantages, potential applications and research topics of the proposed hyper-tether are explained.

We describe two types of seemingly opposing design and control concepts for the realization of a high performance robotic system. One of them is the "coupled drive". It is a design and control strategy to maximize the output power of the robotic system by actively coupling the drive of installed actuators. We show two design examples of the coupled drive; design of leg mechanism and gait control of the wall climbing robot NINJA-II and design of a multi-DOF manipulator CT-Arm. Another is the "GDA", or gravitationally decoupled actuation. This is a design and control strategy to maximize energy efficiency of robotic systems by means of decoupled drive of installed actuators. We show two design examples based on the GDA; design of leg mechanism and control of quadruped walking robots. In the final part of the paper, we discuss a methodology to merge the two above-mentioned seemingly contradictory design methods, and apply the merged concept to posture control of a walking robot on a 3D terrain.

Though development of a practical walking robot is not easy at all, walking robots have many practical advantages resulting from moving functions peculiar to this type of robots including excellent moving characteristics and working characteristics on uneven land. It is cited as a worldwide problem that presently, many antipersonnel mines still remain buried everywhere in the world after the wars injuring many civilians. From humanitarian view points, establishment of a technology which ensures effective removal of mines with safe and inexpensive manner by civilians instead of very dangerous mine removal works done directly by hands is needed. Of specific features shared by walking machines, the authors have been developing a walking type work robot. This robot can walk freely around a buried mine area under extremely severe environments and carry out a series of works such as removal of obstacles before mine removal works, removal of shrubs, mine probing and eventual mine removal. The paper introduces the walking machines developed by the authors so far, a walking type mine removal robot being developed extensively at present and discusses themes and views of development of a practical type walking robot in the next generation which ensures stable movement and works on uneven land. The concept of development of a robot which will be engaged in probing and removal of mines from humanitarian view points is discussed too.

As one of the essential technologies to realize a demining robot, which has the function of searching task for the mines during an autonomous phase and digging task for the mine in a tele-operated phase, we propose the shape-feedback master-slave arm. Feature mechanism of shape-feedback master and slave arm is the articulated finger joints located in the middle of master and slave fingers and their unilateral control to drive master finger joints to have same angle with the slave finger joints, which bend with compliance. Addition of these finger joints under unilateral control of the gripper with conventional bilateral servo control, it is expected to improve the performance of master-slave arm. We demonstrated the validity of the "shape-feedback" master and slave arm by the basic operation experiments and experiments using the model of demining robot.

Walking robots have high adaptability for terrain variation. Mobile robots that perform hazardous tasks such as mine detection or the inspection of an atomic power plant are typically controlled by operators from distant places. For a remote operation system, use of visual information from a camera mounted on a robot body is very useful. However, unlike wheeled vehicles, the camera mounted on the walking robot oscillates because of the impact of walking, and the obtained unstable images cause inferior operation performance. In this paper, we introduce an image stabilization system for remote operation of walking robots using a high speed CCD camera and gyrosensors. The image stabilization is executed in two phases, that is, the estimation of the amount of oscillation by the combination of the template matching method and gyrosensors, and change of the display region. Pentium MMX instruction is used for template matching calculation, and the estimated amount of oscillation is outputted every 12 msec. Furthermore, developed image stabilization mechanism can be used an external attitude sensor from the visual information, and the damping control of the robot body while walking is also possible. Experimental results showed stabilized images that eliminates the oscillation component are taken even when the robot moves dynamically or in long distance, and verified that the performance of attitude control using the developed image stabilization system is almost same as the case using an attitude sensor.

We focus on a heterogeneous robotic system of decentralized autonomous agents with a leader, which we call "super-mechano-colony (SMC)". It has characteristics of both hierarchical and distributed control systems. This paper explains the basic concept and a physical test bed of SMC, and discusses an example, specifically planetary rovers, for SMC.

This paper proposes a quadruped-walking robot that performs "humanitarian demining" tasks. We have already proposed the basic concept of the humanitarian demining robot system, and have several experiments of the operation using the first prototype robot system, VK-I. To accomplish the tasks, we develop several end effecters that can be attached to the working leg. After these basic experiments, we consider to modify the concept, phases of the tasks and to develop the next prototype robot system that will have better performance. The robot will be given a "foot-end-effector changing system" on its back so by utilizing the legs as manipulation arms and connecting various tools (foot-end-effectors) to the foot of the working leg, it can perform all of the procedure of the demining tasks. We discuss the advance of our study and introduce next concept called VK-II.

In the demining application area of a multi-legged robot, one of the important problems is to develop a gait with one or more legs missing. The paper presents a three-legged gait under the assumption that one leg of a quadruped walking robot is missing. We propose a classification scheme of postures for three-legged walking. As one of the basic and reasonable gaits for three-legged walking, the kick-and-swing gait is proposed and analyzed using a simple dynamic model. The minimum energy gait planning and an active shock-absorbing method are investigated. The validity of the proposed gait is shown by experiments using a quadruped walking robot TITAN VIII.

The authors call the group of flexible deformation robots with multiple degrees of freedom "slime robots" (SRs). First the configuration of a robot with multiple pneumatic actuators is described. This configuration makes the most of the characteristics of a slime robot. Next the mechanism of an "SR unit", the minimum drive unit of a pneumatically driven slime robot, is examined experimentally. Next an "SR module" composed of SR units is described. An SR module is the three degrees of freedom pneumatic module with pneumatic actuators, valves, original displacement sensors and a microprocessor in its body. Lastly, as one of application of a slime robot, a "slim slime robot (SSR)" is described. The SSR is a mobile robot with long and thin body composed of serially connected SR modules.

The mechanism design and the fundamental concepts of the dinosaur-like robot called TITRUS-II are reported. It is based on practical concepts so that it can be applied in the real world. The design features include: 1) realizing high dynamic stability by using a neck and a tail as an active damper when the robot walks; 2) standing with the tail to compose a stable supporting triangle so that the robot can work stably; and 3) enabling it to do various tasks by applying a manipulator as a neck. The mechanism of the legs is also distinctive, using a coupled drive to compose four degrees of freedom.

Describes the development of ACM-R2, which is new version of the active cord mechanism with 3D mobility. This ACM-R2 has installed a driving mechanism called "M-drive". This mechanism enables the ACM-R2 to acquire a high output/mass ratio and torque limiting joints, which works as a normal joint and deforms under excessive torque. It has also installed a new type of torque sensor, the "float differential torque sensor" on each joint. Additionally the ACM-R2 has also a self-contained structure with control computer and battery in the joint units. These specific driving mechanisms and the self-contained structure enable ACM-R2 to demonstrate new propulsion methods and motions combining the ability of a manipulator and a locomotor.

We have proposed a new leg-wheel hybrid mobile robot named "Roller-Walker". Roller-Walker is a vehicle with a special foot mechanism which changes to a sole in walking mode and a passive wheel in skating mode. On rugged terrain the vehicle walks in leg mode, and on level or comparatively smooth terrain the vehicle makes,wheeled locomotion by roller-skating using the passive wheel. The characteristics of Roller-Walker are: 1) it has a hybrid function but is lightweight 2) it has the potential capability to exhibit high terrain adaptability in skating mode if the control method for roller-walking is fully investigated in the future. In this paper, the 2-leg trajectory for straight roller-walking is optimized in order to achieve the maximum constant velocity. Also a changeable ankle mechanism was integrated into the Roller-Walker system. Experiments were performed to demonstrate the validity of the concept of Roller-Walker and the results of straight roller-walk experiments are compared with those derived through simulation.

X-screw, a load-sensitive linear actuator that we have proposed, has many desirable characteristics, but one drawback is that the linear motion is much slower than a conventional lead screw because of the method X-screw uses to produce linear motion. When the axial load is small, the transmission efficiency of X-screw is approximately the same as that of a lead screw since the transmitted power is low in this case. Therefore we have developed a dual mode version of X-screw called "DM X-screw". This mechanism is able to automatically switch between lead screw mode and X-screw mode in response to the axial load. This feature makes it possible to apply DM X-screw to many mechanical systems. We have used this mechanism in a pantograph jack that makes use of its dual mode load-sensitive variable transmission properties. This jack can be operated with a small input force and unlike conventional jacks, several of these jacks can be used in combination to overcome the output force limitations of normal pantograph jacks.

In order to realize a practical hyper-redundant manipulator, a new lightweight wire driven transmission mechanism, named M-Drive, has been developed. This mechanism not only takes advantage of the lightweight properties of a wire and pulley system but also has a unique torque keeping function. The mechanism keeps the joint solid without compliance and not only allows the joint to deform when in contact with an external torque over a threshold torque, but is also able to maintain that threshold torque while deforming. Furthermore, M-Drive also features automatic wire elongation elimination, the fundamental difficulty of a wire and pulley system. Combining two M-Drive mechanisms in a differential configuration, a 2-DOF coupled drive actuator that maximizes power has also been developed for a proposed gravity compensated hyper-redundant manipulator named Float Arm. Experimental results for the M-Drive mechanism and the differential M-Drive actuator are also included.

In this paper we outline the design of in-pipe inspection vehicle for pipes with diameters of /spl phi/25, /spl phi/50 and /spl phi/150 mm, respectively. We introduce the concept "whole stem drive". This concept is very effective to allow an in-pipe vehicle to travel long distance in the pipeline. Based on this concept, we have built four in-pipe vehicles, the "Theseus" series. For the pipe with a diameter of 50 mm, we propose two mechanisms, in-pipe vehicle with spiral motion (Theseus-I) and in-pipe vehicle for the practical gas pipe (Theseus-II). For the pipe with a diameter of 150 mm, we propose the in-pipe vehicle based on the idea of control configured vehicle (Theseus-III). Finally, for the pipe with a diameter of 25 mm, we propose the in-pipe vehicle which has an actuator outside of the pipe (Theseus-IV).

This research deals with the development of a load-sensitive continuously variable transmission designed for use as a linear actuator. This mechanism, named X-screw, has several unique features not found in other transmission systems that make it especially suitable for use as a robotic actuator. X-screw has a transmission ratio that automatically changes in response to the load, making it possible to combine relatively high speed motion under low loads with a large maximum load capacity in a much smaller space and with less complexity, than traditional transmission systems. X-screw also has built-in overload protection since it will stop advancing if the load exceeds a certain value although the motor is able to continue to rotate. Furthermore, X-screw can produce arbitrarily slow linear motion from a high speed input, eliminating the need for bulky gear reductions. Experimental tests conducted with a prototype have confirmed the functionality of this system.

To introduce the force control for an uneven terrain walking robot such that it effectively sets the suitable contact pressure of its supporting legs and is able to change from support to swing legs smoothly, the force control for ParaWalker-II, serial/parallel hybrid mechanism that is connected between two frames and contacts ground at three points, is proposed. With this method, the entire leg-drive mechanism acts as a 6-axis force sensor; and the force and moment can be calculated from the changes of each joint angle such that sensors at the ends of the leg are not necessary. Furthermore in the paper; force control and position control can be chosen for each direction in order to smoothly walk on uneven terrain. Smooth contact with the ground by the swing-leg and the changing from swing to support leg is verified through experiments using this force control and measurement method.

We present the development of the "HELIOS" series off-road vehicles and powered wheelchairs that are able to ascend and descend stairs. In this paper, we describe a 6-wheeled vehicle "HELIOS-V", which is equipped with 4 low-pressure tires on the outside and 2 high-pressure tires on the inside. This vehicle has two continuously variable transmissions to change velocity and direction of locomotion. We intend to use low-pressure tires for ascending and descending obstacles such as stairs because of their ability to produce high grip forces on the edges of obstacles. In this paper, we describe the design of the "HELIOS-V", characteristics of the continuously variable transmission, reduction of the driving resistance using the low and high pressure tires and the difficulties while ascending and descending stairs.

A snake is able to attain high terrain adaptability and versatile locomotion even though it has an extremely simple one-dimensional configuration. In order to utilize these functions for robotics, we have adapted the basic biological machine elements of the snake into the active cord mechanism (ACM). We have discussed the creeping dynamics and applications to manipulation. In this paper, we develop a new experimental model named "ACMR-R1" with a self-contained system, which realizes higher mobility and terrain adaptability compared with the past model. Next, gliding experiments on ice were carried out in order to demonstrate that the creeping motion is the same as the principle of skating. Finally, a new terrain adaptive control method for sloping surfaces is proposed, and we verified the effectiveness of it by slope climbing experiments.

A walking robot that has high ground adaptability and the ability to perform various tasks would be extremely desirable in many fields. It can move efficiently in an outdoor environment and on uneven terrain such as stairs, as well as perform tasks. In this paper, for a six-legged uneven terrain walking robot with two body segments, we examine the number of degrees of freedom, movement performance, stability on uneven terrain, and work performance. In addition, we examine the arrangement of the degrees of freedom suitable for practical uneven terrain work by this type of robot. We also propose that a walking robot with an extra leg extension mechanism and a 6-DOF between the body segments is effective. We adopt this design to ParaWalker-II, which we had previously developed, and verify the effectiveness.

Proposes a quadruped walking robot which performs mine detection and removal tasks. Because there are many personnel mines remaining from wars, it is desirable to provide a safe, inexpensive tool which civilians can use to remove these mines. The robot has a tool changing system on its back, so by utilizing the legs as manipulation arms and connecting various tools to the foot, it can perform mine detection and removal tasks. For these tasks, we developed the shape-feedback master-slave arm as a kind of basic technology. When a contact force is applied to the slave arm, the shape of the slave is transmitted to the master arm. We can estimate the force from this shape. We discuss the basic design concepts of the robot system and the shape-feedback controlled gripper.

This paper proposes a new method called "cooperative positioning system" (CPS) for mobile robots position identification. The main concept of CPS is to divide the robots into two groups, A and B respectively Group A remains stationary and acts as a landmark while group B is moving; group B then stops and acts as a landmark for group A. This process is repeated until the target position is reached. Compared with dead reckoning, CPS has a far lower accumulation of positioning error, and can also work in three-dimensions. Furthermore, CPS employs inherent landmarks and therefore can be used in uncharted environments unlike the landmark method. This paper focuses on the the relationship between moving configurations of CPS and its positioning accuracy for the latest prototype CPS model, CPS-III, using simulation and analytical techniques. Optimum moving strategies in order to minimize the positioning error are then discussed and verified through experiments.

Some methods of mobile manipulator control for the articulated body mobile robot "KORYU (KR)" are analyzed. KR is a class of mobile robot composed of serially connected "unit segments", configuring a long articulated body which resembles a train or a snake in shape. This configuration has an intrinsic advantage of making possible the use of the body's degrees of freedom (DOF) not only for "locomotion", but also for "manipulation". In order to demonstrate this characteristic we built a real mechanical model called KR-II, equipped with a 2 DOF manipulator in its foremost part. In the paper, two configurations for augmenting the number of this manipulator DOF are considered. The first method "fixed manipulator" considers the robot fixed to the ground, so that the manipulation control issue can be studied using well-known standard manipulator control theories. In the second method "mobile manipulator" special attention is paid to integrating manipulation tasks with body locomotion (steering) freedom. We verify that mobile manipulation can be smoothly integrated with a steering control method already developed in earlier works. Experimental results are shown to demonstrate the validity of the proposed augmented manipulation configurations and respective control methods.

A new lightweight six-legged robot is developed which uses a simple mechanism and can move and work with high efficiency. This robot consists of two leg-bases with three legs each and walks by moving each leg-base alternately. These leg-bases are connected to each other through a 6-DOF mechanism. Thus, when the robot stands on three legs, or one leg-base is placed on the ground, the other leg-base can be used as a 6-DOF manipulator or active working platform. The output force, velocity, and movable range of various mechanisms for connecting the two leg-bases were compared and the results showed that good performance could be achieved with a serial-parallel hybrid mechanism consisting of three 6-DOF serial linked arms positioned with radial symmetry about the center of each leg-base, each composed of two active and four passive joints. Walking experiments with this robot confirm that this mechanism has satisfactory performance not only as a walking robot but also as an active walking platform.

Design and control of a new quadruped walking and manipulating robot TITAN VII which can be operated on a steep slope is discussed. We first consider the optimal design of a driving system of legs consisting of prismatic actuators so as to produce large output power with minimum weight based on the concept of coupled drive. Secondly, we discuss the criteria for stability on a slope and introduce a new type of extensible leg to maintain high terrain adaptability on a sleep slope. Thirdly, we mention a passive terrain adaptive foot mechanism consisting of a "rocker bogie sole" based on the concept of a connected differential mechanism and including an ankle installed sensor mechanism. The validity of these newly introduced mechanisms has been investigated through walking experiments of the prototype model TITAN VII, including climbing a slope of about 30 degrees using the intermittent crawl gait.

A new leg-wheel hybrid vehicle named "Roller-Walker" is proposed. The Roller-Walker is a vehicle with special foot mechanism which changes to the sole for walking mode and passive wheels for wheel mode. On rugged terrain the vehicle walks in the leg mode, and on level or comparatively smooth terrain the vehicle makes wheeled locomotion by using the passive wheel in the way of roller-skating. The characteristics of the Roller-Walker are: (1) it has lightweight body and hybrid function; (2) it has potential capability to exhibit high terrain adaptability in the wheeled mode if the control method of the Roller-Walking is fully investigated in the future. The paper makes basic simulation experiments and demonstrates basic relations on the terrain adaptive trajectory control method of the Roller-Walk.

Several position identification methods have been used for mobile robots. We propose a new method called "cooperative positioning system (CPS)". For CPS, we divide the robots into two groups, A and B. The group A remains stationary and acts as a landmark while group B is moving. Group B then stops and acts as a landmark for group A. This "dance" is repeated until the target position is reached. By using the concept of "portable landmarks", CPS has a far lower accumulation of positioning error than dead reckoning, and can work in three-dimensions which is not possible with dead reckoning; it can therefore work in uncharted environments. In this paper we outline the second prototype CPS machine model (CPS-II) and report the results of position identification experiments. Experimental results using this model give a positioning accuracy of o.4% for position and 1.0 degree for attitude.

This paper discusses an algorithm to make a quadruped machine walk dynamically and omnidirectionally following a real-time command from an operator. To produce a smooth body motion at high speed locomotion, we introduced a new gait, named the "intermittent trot gait", in which a four-leg-supporting phase and a two-diagonal-leg-supporting phase appear in orders. In this gait, the pitching and rolling motion of the body is suppressed to a lower level than that of the other gaits because the dynamic effects of the swinging legs almost cancel each other. To realize the intermittent trot gait, new algorithms to plan a landing point and body motion are discussed. A landing point is decided by considering an operator command and conversion to the standard leg formation. A body motion is planned to produce dynamic stability and to follow speed and direction commands. By using these algorithms, a mechanical vehicle TITAN VI can walk omnidirectionally, smoothly following a real-time operator command. The top speed is 1 m/sec on flat terrain and 125 mm/sec on 105 mm up and down over rough terrain.

We discuss the development of the quadruped walking robot TITAN-VIII, especially about its leg mechanism and results of experiments using a one-leg model. In the design of TITAN-VIII, we have considered not only about "high performance of the movement" but also about "low cost", "simplicity of the treatment", "simplicity of the functional extension", etc. We introduce a driving system using wires, which is helpful to achieve these objectives. We first constructed a one-leg model of TITAN-VIII. By using this model, we did experiments and made remarks about the feature of response, velocity, force and energy consumption. From these results, we estimated the limitation of the walking velocity of TITAN-VIII in standard walking posture. We discuss the standard walking posture of TITAN-VIII based on the energy efficiency.

On the assumption that a quadruped robot works on a slope, we discuss how to make it prevent tumbling over. The larger the difference becomes between the potential energy of the center of gravity of the initial position and that of the highest position after its rotating, the less the robot tumbles. So this difference can be regarded as stability margin, and a novel gait to obtain largest stability margin is mentioned here. It is an intermittent crawl gait. Its energy stability contour (consisting of equal stability points on the inclined plane) is helpful in the design of standard foot trajectories. An optimal posture on the slope, designed in this way, results in inverse trapezoid shape, which means that upper two legs are located wider than lower two ones. This form worked for the experimental machine, TITAN VII. Furthermore, if the standard trajectory for one direction is combined with another direction trajectory, the quadruped robot can easily switch its proceeding directions, keeping enough stability margin. This sequence is shown.

We discuss methods to evaluate the stability of robots which execute manipulations and locomotion. The relationship between the center of gravity projection point and the ground contact points is an easy-to-use criterion but it does not take into consideration manipulation counter-force. We propose a concept called "tumble stability", which considers the tumble direction when all ground contact points except 2 are hypothetically lost. If a given, hypothetically lost, ground contact point can produce support force which can suppress that tumble, the walking machine will not tumble; otherwise, it will. Stability during manipulations can be evaluated by incorporating the manipulation counter-force as an external force in this evaluation standard. The stability of the planned manipulation can be determined not only on level ground, but on general topography including rugged terrain, wall surfaces and ceiling surfaces. We introduce the concept of the manipulation counter-force limit as an index to indicate manipulation capabilities. Because this indicates the limit value of the counter-force by which a manipulation can be stably executed, it clarifies the fact that it is effective to make the ground contact points on the side opposite from the manipulation farther and wider in order to heighten manipulation performance.

In developing legged robots the most important problems are the design of leg mechanism and the determination of how to drive it. We have already suggested the 'gravitationally decoupled actuation (GDA)' and 'coupled drive' for ground walking robot and wall climbing robot respectively. In this paper, we discuss about these problems for a legged robot in '3-dimensional terrain ', a generalized terrain including not only rough ground but also rough walls and rough ceilings, based on 'GDA' and 'coupled drive'.

This is a report on the development of the Insulator Washer-I, a robot designed to wash the insulators for high voltage lines that are installed on steel towers. The Insulator Washer-I is composed of an orbit rail for ascending the steel tower, a cylindrical coordinate type arm mounted on the orbit rail, and a rotating washing unit which, when transported by the orbit cart and attached to the fin of the insulator by the arm, automatically rotates around the insulator and conducts the washing operation with on-board brushes. A new long stroke, light weight mechanism and a "slant wheel drive mechanism", which produces movement with two degrees of freedom, were introduced into the drive system of the arm in order to clean all surfaces of the insulators, which have a height of nearly three meters. Finally, operational experiments were conducted using the Insulator Washer-I, and the results indicated that practical operation is possible.

Outlines the fundamental considerations for a planetary rover. First, shapes which utilize limitless rotation such as wheels and crawlers, legged shapes, and articulated body shapes were compared, and it was found that the wheel type is currently the optimum for a planetary rover. Next, the authors study specific methods for configuring planetary rovers with one, two, and three wheels, which is a topic that has not been studied much before, and in particular, the authors indicate that it is effective to equip these vehicles with manipulator arms and make joint use of the arm for movement. The authors also study a four-wheel rover, and propose a rhomboid four wheels vehicle arrangement as a mechanism to manifest terrain adaptability comparative to the six wheels vehicle.

This paper investigates an optimal steering control method for the articulated body mobile robot KORYU-II (KR-II), considering energy consumption and trajectory tracking performance as the optimization criteria. The computer simulations of the basic control methods of KR-II's /spl theta/ axis (bending motion between the segments) and s axis (rotation motion of the wheels), lead to the conclusion that the best methods are: the "/spl theta/2 method" combined with the "/spl theta/4 method" for the /spl theta/ axis, and the "s3 method" for the s axis. The "/spl theta/2 method" takes the moving average value of the foremost segment's control angle /spl theta//sub 0/ over a traveled distance L (intersegment length) as the next segment command /spl theta//sub 1/ and then shifts /spl theta//sub 1/ to the following segments according to the moved distance. The "/spl theta/4 method" entails setting a small position control gain for the /spl theta/ axis. The "s3 method" controls the forward velocity of the robot by equally distributed torque commands for all wheels. The experiments by the mechanical model KR-II demonstrated that the introduced control greatly reduces the energy consumption and produces very smooth locomotion; although the trajectory tracking performance is somewhat deteriorated.>

The development of a wall climbing robot which is able to move over the surface of "3-dimensional terrain", a terrain including floor, wall, ceiling of any kinds of structures with agility and terrain adaptability is strongly demanded in many industries. The conventional wall-climbing machines were far from fulfilling the demand, the authors thus have been developing a wall-climbing robot with four-terrain-adaptive legs and basic mobilities were already demonstrated by the manufactured prototype model NINJA-I. However, as there are almost no examples of wall-climbing quadrupedal animals and conventional machines, the gait control method specific for the quadruped wall-climbing is not at all known by now. As the first step to consider a general gait problem of a quadruped wall-climbing robot, this paper investigates a gait of the robot on a vertical and flat wall. The gait is analyzed with the criterion to maximize the locomotion speed under the constraints of predetermined conditions of the supporting-legs position, order and phases of swing legs to prevent turn over motion. As a result of the analysis, the optimal standard gait, named "Wall Gait", is shown to maintain foot posture of /spl Lambda/ shape and moves the leg in the order of leg1-leg2-leg4-leg3 in static walk and the order of "pace" in dynamic walk.>

This paper discusses foot force control of a quadruped walking vehicle on rough terrain. The proposed control algorithm has two parts. One is a feedforward control to produce a smooth touch-down and lift-up motion of the leg. The other part is a feedback control to maintain the body's posture under the conditions of some disturbances. A command force of the feedforward control is calculated beforehand from the data of the body's position, its acceleration and leg positions. The force increases smoothly from zero after touch-down on the ground, and it decreases smoothly to zero before lift-up. On the other hand, a command force of the feedback control is calculated from the data of the body's posture measured by gyroscopes. The effect of the feedback control is as if the body is suspended to an absolute frame by springs and dampers. Therefore, it is called 'Sky-Hook Suspension'. By this control-algorithm the experimental vehicle TITAN VI is able to walk smoothly on a rough terrain.>

This paper proposes the concept, and explains the characteristics, of a new group robot "Gunryu", each segment of which has autonomy but at the same time moves and operates cooperatively with the other segments. Next, the mechanisms of a primary model, GR-1, which is comprised of two prototype robot units, are introduced and the conditions for operational experiments are given.>

The paper discusses a general design method for robotic actuation mechanisms which is based on the concept to prevent power consumption in the process of negative work. The author's past experiences are exemplified as the introduced design method; e.g. GDA, an energy efficient leg driving system for walking vehicle and IB magnet, a permanent magnet device which can be released with zero force. Two types of non-energy dissipation actuator system including rotational and translational motions are newly proposed based on the concept for the future actuator system of space robots. A translational non-energy dissipation arm with tether link, named Chameleon arm, are proposed and its basic mechanism is discussed.

The authors have developed an articulated body mobile robot, Koryu (KR), which is structured by multiple segments that are actively connected. They report on a specific motion control method based on the impedance concept that fuses posture control, which constantly maintains the posture of the entire robot body, and force control, which optimizes the distribution of support force on each wheel, in order to improve adaptability to irregular terrain. The effectiveness of the control method is verified by running experiments in which prototype models KR-I, KR-Im, and KR-II flexibly followed a ground surface of unknown shape by optionally controlling the distribution of support force while maintaining perpendicular posture.

A nine-degree-of-freedom multijoint manipulator called the CT ARM-I has been developed. The CT ATM-I is based on the concept of coupled drive and the connected differential mechanism, and thus the force for lifting a payload does not concentrate on one actuator but is distributed among all actuators. This manipulator has a specific tendon traction force transmission mechanism in which a pair of tendons for driving a joint are pulled from base actuators via pulleys mounted on the base-side joints. The mechanism uses the coupled drive function of the tendon traction forces and thus enables the lightweight manipulator to exhibit high payload capability. Through the experimental study, it was demonstrated that the CT ARM-I has an active compliance arm and offers payload capability far superior to conventional designs.>

The authors previously (1989) proposed the concept of dynamic and static fusion gait control and discussed a basic control scheme for the purpose of adaptive selection of these gaits during continuous walking. They extend the concept to walking at variable speeds along a winding path. The motion scheme is discussed on the basis of a generalized trot gait and incorporates stability control based on feedforward and feedback control; trajectory modification is based on the zero moment point concept. The validity of these discussions is verified by walking experiments with quadruped walking vehicles TITAN IV and TITAN VI; e.g., dynamic and static fusion gaits at velocities from zero to 400 mm/sec by TITAN IV, and walk with dynamic stability along a circular winding path at a velocity of 100 mm/sec by TITAN VI. At present, dynamic walk on rugged terrain is not possible, but it may be made possible by introducing feedback control as discussed.>

Real-time stereo vision using a multiple arrayed camera system, named MAC vision, is proposed. MAC vision processes the correspondence problem, one of the basic problems in stereo vision, very rapidly by making use of the simple geometric relationship of images on the same-height scanning lines. Several problems involved in MAC vision are discussed. The results of experiments performed on a newly constructed five-camera prototype are presented. The experimental results showed that a speed of 16 (frames/s), where each frame included 1800 points.>

A newly developed TerrainAdaptive Quadru-Track carrier robot, or 'TAQT Carrier', is described. The TAQT Carrier is 310' kg in weight including a 70 kg battery pack, 1300 mm in length, 860 mm in width and 970 mm in height. It can carry a payload of 100 kg on a level floor and 80 kg on stairs of a maximum incline of 4Odeg. With the battery pack, it is self-sustained and can move continuously around uneven terrain, such as a construction site, under wireless control for about 2 hours. The TAQT Carrier has inherited some technologies introduced in its immediate predecessor, the t errain adaptive qnadru-track vehicle HELIOS-11: It uses 'equilibrium crawlers', crawlers which are connected to the chassis through pivot axles at the centers of the tracks, and it incorporates a coupled drive system for each pair of crawlers to take full advantage of the output power of the motors. New features are a torque sensor which employs photosensors at the planetary gear and a solid and reliable posture control device for operation on steep stairs named the 'RC mechanism'. The RC mechanism maintains the bed in a horizontal orientation and keeps the center of gravity of the vehicle over the central part of the tracks. Preliminary tests have confirmed the high terrain adaptability of the TAQT Carrier Robot.

A coupled tendon-driven manipulator called the CT arm is introduced, an its control is discussed. The CT arm has a specific tendon traction force transmission mechanism in which a pair of tendons for driving a joint are pulled from base actuators via pulleys mounted on the base-side joints. The mechanism makes the most of the coupled drive function of the tendon traction forces and thus can exhibit enormous payload capability. The CT arm is solidly structured and can be inexpensively manufactured because of its mechanical simplicity. A control algorithm which minimizes the square sum of the traction force of tendons while satisfying given restrictions is introduced. The validity of the control method is shown by computer simulation.>

A coupled tendon-driven manipulator, CT arm, is presented. In its tendon traction force transmission mechanism, the pair of tendons driving a joint is pulled by base actuators via pulleys mounted on the base-side joints. The mechanism uses coupled drive function of the tendon traction forces and thus exhibits a large payload capability for such a light-weight manipulator arm. CT arm has a solid structure and can be manufactured inexpensively because of its mechanical simplicity. Through experimental simulation, it is known that CT arm has the structure of a variable compliance arm and has an unusually large payload capacity.>

A six-axial force sensor using the optical measuring technique and its nonlinear calibration method are proposed. The force sensor is based on a unit which has a small light source set face to face with a photosensor of the quarter-splitting type to measure minute displacements in two directions with respect to each other. Three sets of the unit are held by an elastic frame. The sensor, in comparison with the conventional strain-gauge-based device, is more compact, light in weight, low in cost, and accurate. The high accuracy of the sensor comes from the calibration method in which nonlinear interferences of six-axial force are considered. An experimental setup in which the six-axial force sensor could be simultaneously input with plural axial forces was produced, and the proposed calibration method was shown to be valid.>

A control method called redundancy decomposition control is proposed for the resolved acceleration control of a manipulator equipped with redundant degrees of freedom. In this method, the redundant degrees of freedom of a given manipulator are decomposed into nonredundant subsets. For every time interval from t to t+ Delta t, the acceleration of the corresponding subset of degrees of freedom is assumed to be controlled and the inverse kinematics and dynamics as well as the evaluation function are calculated using the nonredundant inverse Jacobian matrix. The calculation is performed in parallel for all the combinations of degrees of freedom. The optimum set of degrees of freedom is selected and it is used for the control of the time interval t to t+ Delta t. The proposed method is reviewed in comparison with conventional approaches, including the pseudoinverse matrix and null-space vector techniques. It is demonstrated that the proposed method almost always realizes better motion planning than the other two techniques, and is effective in real-time control.>

A robot system design to minimize the robot weight while producing multi-degree-of-freedom (DOF) functioning is proposed. This method aims to couple mutually the degrees of freedom of the robot in such a way that, so far as possible, they can be jointly driven in the robots most common modes of operation. The method is called coupled drive. As an evaluation function for the coupled drive, an actuation index, which is the ratio of the power for the actuation to the whole output power to be provided to the robot system, is introduced. A simulation experiment involving a quadruped walking robot with suckers ascending the vertical surface of a wall is carried out. The experiment deduces by linear programming a walk by which the actuation ratio of the robot is maximized when specific configurations or gaits of the walking robot are given.>

A control system for a shape memory alloy (SMA) servo actuator, and its application to a unique medical tool, are considered. It is thought that the electric resistance value of an SMA can be utilized to monitor the transformation of the SMA directly. Therefore, an antagonistic transformation control scheme using electric resistance feedback is proposed and is verified by several experiments. This control scheme reduces the open-loop hysteresis of an SMA actuator and improves greatly its robustness against heat disturbance due to changes in the cooling condition. Research into the application of the method in an active endoscope is reported. It consists of five segments of 13 mm diameter, 40 mm length each. The bending angle of each segment can be controlled individually from outside by using antagonistic electric resistance feedback without any motion sensors. A model for smooth insertion to the colon is verified.>

The authors have developed a laser range finder (LRF) which enables a mobile robot to measure the distance to a natural object located 1-5 m ahead with an error less than 2%. The system uses a laser as weak as 1 mW, a safe level for human eyes, and is workable under bright daytime sunlight of about 100000 lx. This LRF can quickly process data and makes real-time measurements of objects located ahead. It features plural redundant range-measuring systems and a novel real-time signal. The effectiveness of the LRF system has been demonstrated under direct sunlight by an experimental model mounted with two CCD cameras and a semiconductor laser with output power of 1 mW (830 nm).>