A haptic device using flexible sheet is developed. This device elongates a rubber sheet with four servo motors in parallel. Controlling their motor angles varies softness of the sheet: stretched sheet feels hard, and loose sheet feels soft. Hence a user can feel different softness of virtual objects when he pushes the sheet directly with his finger. We apply this device to haptic feedback of real soft objects. The system consists of the haptic device and a robot with a pressure sensing device. This sensing device is a rubber hemisphere filled with air. The internal pressure is measured when the hemisphere is pressed against an object. First a user pushes the center of the sheet. The movement of the side edge of the sheet is observed with a close-up camera, and the user's pushing pressure on the sheet is estimated. Next the robot pushes a target object so that its pushing pressure on the object, which is measured with the pressure sensing device, may coincide with the user's pushing pressure on the sheet. At the same time, the softness of the object is estimated from the measured pushing pressure on the object and the indentation of the object, which is given by the robot's movement. Then the haptic device controls the motor angles so that the sheet's softness may be equal to the object's softness. The system repeats this process in real time. In this way the user feels the same softness as the real object by pushing the sheet. As an experimental result, the developed haptic device can imitate softness of a real stuffed doll.

A working six-legged robot which can switch three modes for locomotion and manipulation was already developed. In its vertical four-leg two-arm mode, lower four legs are used for locomotion and upper two legs for manipulation with its body vertical to the ground. In order to expend capabilities of this robot, a method of pushing a large object in this mode is proposed. The robot holds the object using its upper two legs and body. The robot leans against the object and applies pushing force. Then it walks by moving the outer and inner pairs of the lower four legs alternately. Because of this symmetric walking, the robot can push the object with keeping lateral balance. It can apply large force owing to the effect of its body weight. Because holding the object firmly, the robot can push the object stably without falling down. For comparison, two methods are also analyzed. First the robot simply walks by tripod gait with its body touching the object. Second the robot pushes the object using its upper two legs and walks using its lower four legs in vertical four-leg two-arm mode. Then the merits of the proposed method are clarified. Three methods are experimentally ascertained using the developed robot.

A haptic device using transparent flexible sheet, which is an improvement of our previous one, presents visual and haptic sensations when a user pushes a virtual soft object. It consists of a transparent flexible sheet and a computer display; the display is placed behind the sheet. The user feels the softness of the object by pushing the sheet, and sees the stereoscopic CG image of the deformed object through the sheet. In the present study we propose a new method of detecting finger touch on the sheet and measuring the indentation of the contact point; the method is specialized for this haptic device. A camera is placed behind the sheet. A checkered pattern is reflected on the backside of the sheet like a two-way mirror. The camera monitors this reflected pattern. When the finger pushes the sheet, the sheet is deformed. Then the reflected pattern near the fingertip, seen from the camera, is distorted. Monitoring this distortion makes it possible to detect finger touch on the sheet. As the indentation of the contact point increases, the reflected pattern is more distorted. Thus measuring the amount of the distortion allows the measurement of the indentation. The proposed method is ascertained by some experiments.

Recently multi-legged walking robots are widely developed. For these robots to walk safely, a sole sensor with high performance is desired. In the present paper, an arrayed type tactile sensor made of flexible silicone rubber, which is based on micro-electro-mechanical-systems (MEMS) technology, was developed. This sensor was applied as a sole sensor of a legged mobile robot. By processing the force data from many sensing elements using neural networks, information of contact force, i.e., three dimensional x, y, and z components of force vector, was able to be detected, which was confirmed by both simulation and experiment.

A haptic device using flexible sheet and air jet is proposed. This device presents haptic sensation of virtual lumps under skin to user's finger. A tensioned flexible sheet is regarded as virtual skin. A user touches the sheet directly with his finger. Then he feels the softness of normal skin as the sheet compliance. A nozzle fires thin beam of air jet to the sheet from its back, when the user touches the sheet at the location of a virtual lump. The fingertip feels the small hard part made by the air jet through the sheet. This can be the virtual lump. In order to present multiple virtual lumps, the nozzle is attached to a manipulator. A camera measures the fingertip motion, and the manipulator moves the nozzle together with the fingertip. The nozzle fires the air jet when the fingertip is on the virtual lumps. We can vary the hardness of a virtual lump by controlling the flow rate of air. We can also vary the size of the virtual lump by controlling the distance between the nozzle and the sheet; the shorter distance makes the virtual lump smaller. This is because the air jet radiates out from the nozzle. Some experiments of presenting multiple virtual lumps and varying the hardness and size of a virtual lump are performed.

A ladder climbing motion for limb mechanism robot “ASTERISK” is proposed. This robot has six legs. The upper three legs hold on the upper rung from its both sides alternately, just like pinching it. The lower three legs hold on the lower rung in the same way. Hence the robot can climb the ladder stably. Depending on the posture of the robot, when it lifts up its body, the robot automatically selects the legs supporting the robot’s weight and distributes the weight to these legs based on their force margins. The legs which cannot support forces are controlled to always contact with the rungs so that the robot holds the ladder firmly. The advantages of proposed gait and control method are verified by the analysis of the supporting range and the torque, and by experiment on force distribution.

Psychological acceptance among users must be considered when service robots intended to work in a human population. We assessed such psychological effects using virtual reality instead of actual robots. Subjects filled out questionnaires after viewing computer graphics (CG) images of robots. Based on questionnaires, we identified potential psychological effects. In earlier work, we defined impressions made by robots on viewers using an abstract robot model. Here we define effects that robot appearance and performance have on users, varying parameters. We also define changes in impression due to colors thought to significant affect human psychology in the same way as robot appearance and performance.

An encountered-type visual haptic display using flexible sheet is proposed; it allows users to feel like seeing and pushing virtual soft objects directly. Both edges of a translucent flexible sheet such as rubber is attached to two manipulators. They apply bias tension to the sheet by pulling it from both sides, thus varying the sheet compliance. A user can feel the compliance of a virtual soft object by pushing the sheet with his finger directly. The motion of the finger tip is measured by stereo cameras. The manipulators also change the pose of the sheet along the object's surface together with the finger tip motion. The user can touch different points of the object and feel like stroking it with his finger. This sheet is also used as a rear projection screen. From the measured finger tip position, the deformation of the object is calculated by FEM. An LCD projector projects the CG image of the deformed object stereoscopically on the sheet from its back. The user can see the 3D image through stereoscopic glasses and touch the image directly. A method of correcting the CG image distortion caused by the movement of the sheet and the depression of the pushed sheet is proposed. A virtual soft cylinder is expressed by a prototype display: the stroking of the cylinder and the correction of its 3D image are evaluated.

Real-time emergent stop walking motion is necessary for humanoid robots. We propose a new emergent stop method using modification criteria map. The stable gait change is generated by adjusting the amount of the ZMP modification according to the timing of stop command. The modified ZMP trajectory is given so that the humanoid robot can change the current motion without falling down. The modification criteria are defined from the relation between the predicted ZMP trajectory using a preview controller and the support polygon. The preview controller employs table-cart model and it derives center of mass (CoM) trajectory from ZMP reference in real-time. We make the map of relation among the ZMP modification length, the modification timing and the timing of the stop command for stable gait modification. The robot can execute the best motion referring to the predefined map. In this method, the humanoid robot can stop immediately within one step or zero step to avoid a collision, if humans or objects appeared unexpectedly in front of the walking humanoid robot. The stop motion is typically divided two phase: single leg support phase and double leg support phase. In the single leg support phase, the next landing position and timing are decided according to command time of the stop signal. In the double leg support phase, the humanoid robot can stop anytime without changing standing position. The validity of the proposed method is confirmed by experiment using a humanoid robot HRP-2.

This paper investigates a calibration of a parallel mechanism stage which is set up under the microscope. The calibration method uses the measurement data of the translation movement in the plane of the end-effector and rotation about the axis perpendicular to it using measurement method with the micro grid pattern. This paper discusses its calibration method with experiments for the stage constructed a fixed linear actuated parallel mechanism. The results show that the calibration using limited data is possible and has good performance

A method for limb mechanism robots of omni-directional gait hanging from grid-like structure is proposed. Grid-like structure consists of many bars assembled in a matrix in a horizontal plane; its grid spacing is not always constant and unknown. A robot has six legs, and each foot has a hemispherical shape for hooking on the bar. The robot moves in any direction as commanded by tripod gait; it hangs from the grid-like structure using two sets of three legs alternately. The leg gropes for the bar so as to take as long stroke as possible. By increasing joint compliance, the foot contacts the bar softly and detects the contact. Then, using a foot force sensor, the robot ascertains that the foot hooks on the bar. The developed robot ASTERISK can perform omni-directional gait hanging from experimental grid-like structure by the proposed method

A compact and yet economical 3-DOF micro/nano finger manipulator based on micro parallel kinematics structure is presented in this paper. It uses three piezo-electric actuators and two types of flexure joints, one is a revolute joint and the other is a ball joint, as its main mechanism. The problem of inverse kinematics between end effector position and actuator displacements along with the Jacobian matrix for this design is derived. A glass needle of 3 to 10 cm length is used as the end effector to increase the workspace of the micro/nano manipulator. As the length of the glass needle end effector is decreased, the resolution and accuracy of the manipulator is increased while the workspace volume is decreased. The design parameters are optimally chosen so that the manipulator will obtain maximum workspace volume. The simulation results illustrate that the proposed model has a large workspace and in the same time it will be small in size using the proposed architecture

Marionette system provides an intuitive teleoperation system for the difficulty controlling whole-body motion of a multi-joint robot and the complicated observation of its condition. This system employs a small robot which has similar form to a control target as an operating/displaying device, so that the device provides an operational feeling like manipulating a doll, so it is named Marionette device. Since the characteristics of the Marionette device and the target robot are synchronized bilaterally in the system, the operation of the Marionette device is reflected intuitively in the target, and the robot motion is also displayed simultaneously by the Marionette device. In this paper, we develop a humanoid type device as a Marionette device in order to operate a humanoid robot HRP-2 and implement a wholebody teleoperation method. The remote walking and manipulation experiments in an unknown environment are introduced. In this experiment, the operator should guess the remote environment using head camera view and control legs and arms by the Marionette device. We propose a new operation method for controlling the foot position and leg joints with the Marionette device. It makes possible to walk by pointing a foot stamp step by step in a stable place

This paper describes a real-time gait change for a walking humanoid robot. We propose a control method to change the gait motion by modifying a pre-defined zero moment point (ZMP) trajectory in real time. The stable gait change is generated by adjusting the amount of the ZMP modification according to the timing of stop command. The modified ZMP trajectory is given so that the humanoid robot can change the current motion without falling down. The modification criteria is defined from the relation between the predicted ZMP trajectory using a preview controller and the support polygon. The preview controller employs table-cart model and it derives center of mass (CoM) trajectory from ZMP reference in real-time. We make the map of relation between the ZMP modification and the timing of command for stable gate modification. The robot executes the best motion referring to the map. In this method, the humanoid robot can stop immediately within one step to avoid a collision, if humans or objects appeared unexpectedly in front of the walking humanoid robot. The stop motion is typically divided two mode; single leg stop motion and double leg stop motion. The stop mode and the next landing position are decided according to the command time of the stop signal. The validity of the proposed method is confirmed by experiment using a humanoid robot HRP-2

In this paper, a wide-area recognition technique for mobile robots, which proves to be specifically effective with biped robots, using Hybrid Motion Stereo is presented. The proposed technique uses several cameras and divides the field of view into two groups, namely, areas visible in more than two cameras (MCVA : Multiple Camera Visible Area) and areas visible in only a single camera (SCVA : Single Camera Visible Area). Positional informations contained in MCVA can be computed constantly by stereo vision, while those contained in SCVA require movement of the camera to be computed by motion stereo. Estimation of the movement of cameras can be obtained by calculating the movement of immobile objects in MCVA. The measure of precision in computation by motion stereo depends on the magnitude of the movement of points in the image. Thus, high precision in SCVA can be obtained by lateral or longitudinal motions of the cameras. One such motion can be generated with biped robots for its lateral cyclic motion caused by the movement of the center of gravity for stability retainment. The authors have implemented these methods into the humanoid robot HRP-2 and evaluated the effectivity of the technique.

This paper discusses pushing a heavy object by a humanoid robot. We modify the whole body motion considering the hand reflecting forces for the walking pattern of a humanoid robot. By assuming that linear and angular momentum of a humanoid robot are calculated, we define the projection of the Center of the Mass(CoM) as” Dynamically Complemental Zero Moment Point(DCZMP)”, when external forces act to the end-effectors. We propose a new method using the DCZMP for the modification control of CoM position with balancing control. The robot can keep the dynamical balance considering the DCZMP and the walking velocity in both single and double support phase. In addition, for controlling pushing force, we implement an impedance controller with the manipulation and walking velocity controller. The effectiveness of the proposed method is confirmed by simulations and experiments.

In this paper, the mechanical properties of yeast cell are determined by means of the developed two-fingered micro hand and an atomic force microscope (AFM). The micro hand has excellent absolute positioning accuracy after the elaborated calibration, and is typically capable of obtaining less than several hundred nanometer of positioning accuracy by human tele-operation. The authors also developed an AFM system of our own composition. The AFM consists of a laser diode module, a cantilever, a 4-segment photodiode and output circuit. The task to measure the mechanical properties of cells include moving of the fingers from the home position to the target object (cell), then picking and grasping it, moving it to a target position (AFM tip), and finally pushing it against the cantilever tip. However, since it is difficult to stabilize the sample, the authors utilized the capillary phenomenon, i.e. the liquid inside the tube-shaped object ascends the inner wall in order to stabilize the sample strongly. And force-indentation relation was obtained applying a force to individual yeast cells by moving the sample to the cantilever tip. Force is automatically calculated from the cantilever deflection measured with a laser beam and a quadrature photodiode, while indentation is obtained from the difference between the movement of the micro hand and that of the cantilever tip caused by cantilever deflection. The mechanical properties of yeast cells is finally determined using the produced force-indentation curves, the Hertz model and FIEL (force indentation to equal limits) mapping, which is an analytical way for determining relative microelastic properties from force volumes of viscoelastic materials.

Robots working in complex environment require accurate perception of a wide field of view. Using cameras, hybrid motion stereo, which combines the computations by stereo vision and motion stereo, is capable of acquiring positional information of the whole field of view. However, the technique generates errors in computation by motion stereo when tracking feature points fails. This paper describes a method to reject the outliers to avoid erroneous recognition. The method uses computation results from several previous images, computing the spatial deviation and temporal deviation of points, and rejecting those considered to be deviated. The evaluation function is composed with a weighted average of the sequential results, each with a weight of the total number of points existing in the neighboring space, which represents the spatial deviation. Experimental results using the humanoid robot HRP-2 denote the effectiveness of the method.

In this paper, we propose new method for the task of pushing an object by a humanoid robot. First, a humanoid robot leans against the task object whose mass and shape are known, and it makes multipoint contact states which the whole body is supported by both hands and feet. We focus on two support polygons which consist of the both hands and one foot, and we make them include the center of mass (CoM). In this case, the humanoid robot doesn't need to move the CoM for walking and it is easily possible to make stable gate motion. The force control considering the pushing force and the acceleration control of the CoM are implemented for the gate velocity control. Experimental results show the effectiveness of the proposed method.

This paper proposes a gait control algorithm for limb-mechanism robot on rough terrains and slopes. The concept of the "limb-mechanism" is to integrate functions of legged locomotion and arm manipulation. A limb can be used as a leg and an arm according to different situations. Each limb radiates out in six directions and the robot has a symmetrical configuration in horizontal and vertical directions. The robot can walk into any direction using a simple motion planning where the same trajectory is assumed in each leg. This trajectory is generated on a cylindrical volume which is defined in the leg workspace. The robot has a touch sensor at the tip of each leg. The sensor can detect the contact with the ground, and the legs can stay on the ground stably. When the robot walks on a rough terrain, the body is inclined in parallel to the virtual plane defined by leg supporting points in order to use the leg workspace effectively. The stability margin of the robot can be also improved easily by changing the leg trajectory.

When robots coexisting with humans are designed, it is important to evaluate the influence of the shape and size of the robots and their motions on human sense of security. For this purpose, an evaluation system of human sense of security for coexisting robots using virtual reality is discussed. Virtual robots are visually presented to a human subject through a head mounted display; the subject and the robots coexist in the virtual world. Some kinds of physiological indices of the subject are measured, he answers the questionnaire about his impression of the robots, and his sense of security is evaluated. Because of using virtual reality technique, the shape and size of the robots and their motions can be easily changed and tested. In the present report, pick and place motion of humanoid robots is evaluated. As a result of analyzing the questionnaire, it is found that turning the body coordinating with the arm gives good impression on humans.

An integrated visual and haptic display using translucent and flexible sheet such as rubber is proposed. This display varies the compliance of the sheet in the normal direction by changing the bias tension of the sheet: tightly stretched sheet feels hard, and loosely stretched sheet feels soft Hence a user can feel compliance of various virtual objects when he pushes the sheet. This sheet is also used as a rear projection screen; an LCD projector projects the image on the sheet from its back. When the user's finger pushes the sheet, the position and deformation of the pushed point are measured by stereo vision. The deformation of the virtual object is calculated by FEM, and the graphical model of the deformed object is generated. The user sees both the image of the object projected on the sheet and his own finger pushing the image. As a result, the proposed visual and haptic display allows users to feel like pushing virtual soft objects with their fingers directly. It is ascertained that the developed display can generate variable compliance and simulate the compliance of a real soft object. Human subjects feel like seeing and pushing a virtual object directly.

This paper proposes a method of building a 3D map composed of static objects for localization of mobile robots using recognition of human actions. In the monitoring systems with fixed cameras and also moving cameras, high-precision localization of moving cameras is required for measuring human actions in detail and precisely. A 3D map of the environment composed of static objects such as walls, desks and shelves is useful for high-precision localization of moving cameras in 3D space, because salient features in the environment are used as landmarks. Furthermore, the 3D map is required for generation of monitoring motion of the moving cameras and recognition of human actions in the relation of the environmental objects. In order to generate a 3D map automatically by measuring 3D points in an environment, points on static objects have to be selected from measured points, because there are dynamic objects such as chairs, books, and other mobile things in the environment. The proposed method generates a 3D map for localization by selecting points on static objects from measured 3D points based on recognition of human actions. Experimental results show feasibility of our proposed method.

Mobile manipulation control method for humanoid robots provides good manipulability and stability on manipulation tasks. This method leads whole body motion and locomotion, when the manipulator tip trajectory is decided. For the dexterous manipulation, the robot has to cope with the unexpected forces acting to the hands. By assuming the statistical balance, we define the projection of the CoM as "complement zero moment point (CZMP)", when the external forces act to the end-effectors. We propose to use the CZMP for the modification control of CoM with balancing control. The method is implemented to the mobile manipulation control method and the effectiveness is confirmed by the experimental results.

We propose "marionette system" as a master slave teleoperation. The operation/display device which presents form and posture equivalent to the remote robot is named "marionette device". In the system, it is possible, making exact discrimination, to control flexibly the remote robot by using marionette device. Marionette system is the operation/presentation technique which not only enables to operate flexibly all movable joints but to discriminate correctly by checking the marionette device. Since the condition of the marionette device is made almost equivalent to the remote robot, the operator can check and operate the device as treating a doll for judgments of operation. Thus, we named the control system "marionette system." In this paper, we develop the humanoid-robot (HR) type device as an example of the remote control of the humanoid robot. When a humanoid robot is set as an operation target, it becomes easy to transpose and image a robot pattern from human motion. HR type device used as operation/display equipment enables intuitive approach in operation. In order to verify the validity of the proposed system, we have carried out various experiments comparing two types of device. One is conventional the method employing graphic simulators and a joystick, the other is a proposed control/display device employing humanoid type device. The effectiveness of the proposed system is confirmed by the experimental results.

A control method for humanoid robots of mobile manipulation is proposed: this method allows accurate manipulation using hands, even when the robots move around. A robot controls its body pose and steps so that manipulabilities of both arms and robot stability can increase, coordinating with the motion of both hands for performing objective tasks. Because of the vibration caused by the impact of foot landing and the slip of the feet, the accuracy of the hand positions and robot stability decrease. For this problem, the robot measures real hand positions and body orientation with its camera and gyroscope. Then the hand positions errors are transformed to correcting joint angles of the arms using arm Jacobian matrices. Adding the calculated joint angles to the desired joint angles of the arms, the arms can compensate the hand positions. New desired joint angles of the legs are calculated by inverse kinematics from real foot positions and desired shoulder position. Adding the correcting joint angles to the desired joint angles of the legs, the legs can compensate the shoulder position, thus increasing robot stability. The effectiveness of the proposed method is ascertained by simulations.

A control method for humanoid robots of mobile manipulation is proposed. A robot autonomously steps or controls its body pose while performing various manipulation tasks with its hands; that enables dexterous and stable manipulation. Two hands always move along their desired trajectories by impedance control for carrying out a given task. Coordinating with this motion of the hands, the robot controls its body and legs so that arm manipulability and robot stability may increase. It determines the next foothold by evaluating manipulabilities of both arms, shape of stable region and moving direction. An evaluation function consisting of manipulabilities of both arms and static stability of the robot is defined, and the robot steps if the new double support state is better than the current one. Both in double and single support states, the robot controls its body pose using the support leg(s) so that this evaluation may be optimal. Various motions of a humanoid robot by the proposed method are simulated.

Calibration methods and parameter estimation analyses of a class of parallel mechanisms are discussed in order to achieve a nano-modon stage applied in the machining of high quality optical devices. The paper includes mechanical structure of Delta type parallel mechanism, its kinematics analyses for calibration, two calibration methods and their comparisons in the aspects of parameter errors, final achieved accuracy and simple procedure. Exclusion of orientation data will be also discussed for the simplicity of measurements in the calibration procedure.

The optimal posture of a humanoid robot for generating large desired force at its hands is discussed. The robot is required to stand stably and to support the force and its weight under the constraint of maximum joint torques. Furthermore, it is important to keep the robot controllable against sudden change in the force. From this point of view, an evaluation function for the task with large force based on statics is proposed; we focus on Jacobian matrices of two arms and legs to give the robot adaptability to force change. Then the method of obtaining the optimal posture, footholds and joint torques of the robot is described. Effectiveness of the method are verified through computer simulations.

An automated calibration for micro-hand is proposed to obtain high quality micromanipulation system. The calibration is based on automatic focusing of micro-object and its position detection in the microscope frame using microscope images. The automatic focusing works well even in the tracking of moving target using chromatic aberration. The finger position can be detected automatically by integrating focusing and identification of the micro-hand finger wherever it is in the microscope view. These automated processes are implemented in the actual system. The experiment shows the system can attain around 2[/spl mu/m] in absolute positioning accuracy.

We propose a method of relocating storage devices attached to the environment for sharing knowledge efficiently among multiple robots. If a robot stores acquired knowledge into the storage device, other robots can achieve the task by using the knowledge. Since the memory size of the storage device is limited, usefulness of the knowledge is evaluated with respect to the reducible cost. A memory unit containing useless knowledge is removed from the storage device and added to the device where more useful knowledge is required. Then, the robots can store useful knowledge for the whole environment and the memory units are flexibly relocated according to the change of a series of the tasks. The simulation results of multiple robots navigation for repetitive transportation tasks show the effectiveness of our method.

This paper describes a method of analyzing the error of dead reckoning of multilegged robots. In dead reckoning of multilegged robots, the body posture and contact positions of legs are alternately estimated. The estimated error is accumulated in locomotion. We derive the basic equations for estimation of the error of body posture and the contact positions based on the small displacement analysis. The 3D distribution of the error is analyzed by singular value decomposition.

Proposes a method of object recognition using appearance models accumulated into a RFID (radio frequency identification) tag attached to the environment. Robots recognize the object using appearance models accumulated in the tag on the object. If the robot fails in recognition, it acquires a model of the object and accumulates it to the tag. Since robots in the environment observe the object from different points of view at different time, various appearance models are accumulated as time passes. In order to accumulate many models, eigenspace analysis is applied. The eigenspace is reconstructed every time robots acquire the model. Experimental result of object recognition shows effectiveness of the proposed method.

A real-time control method for a humanoid in mobile manipulation, doing tasks with its arms while moving, is proposed. The arm tips always follow their desired position with external force applied by impedance control, for carrying out a given task with the arms. An evaluation function consisting of not only stability but also arm manipulability-both are important for mobile manipulation-is defined; the humanoid controls its body and legs so that this evaluation may be optimal. As a result, the humanoid autonomously steps or keeps standing, coordinating with the arm tips motion. The effectiveness and usefulness of the proposed method are ascertained by computer simulations on a humanoid of human-size and experiments using a small experimental robot.

There has been always a workspace problem with parallel mechanisms. This paper discusses the workspace of the parallel mechanisms and its enlargement by adjusting their link parameters. The basic idea is to cover a whole required range of workspace with small pieces of one. A fixed linear type mechanism is selected to analyze and to evaluate its adjustable workspace. The analyses of simple 2 DOF plane model show that additional spaces are obtainable, which cannot be reached by the conventional mechanism due to its singularity. More detailed analyses and evaluations are discussed based on a 6 DOF spatial model.

The concept of virtual operating environment (VOE) used for teleoperation of various machines is proposed. A virtual cockpit for each machine is constructed within a computer: it consists of virtual input devices such as switches and joysticks, meters or indicators, and TV monitors displaying the images from the machine-mounted cameras. The cockpit is displayed to an operator through a head-mounted display. In the real world, a manipulator presents the virtual input devices by turns; the operator handles the end-effector of the manipulator, regarding it as the input device. VOE can provide different types of operating environment for various machines simply by switching softwares. One of the most important techniques for VOE is the simulation and presentation of various input devices with a manipulator. The manipulator simulates the switch using the obtained impedance model. It is ascertained by experiment that the manipulator can present two different switches.

A hybrid cylinder/cable drive parallel arm and its motion control are discussed. The basic idea of the hybrid parallel arm is to make the best use of the mixture of the high power cable drive and the cylinder actuation to obtain a heavy-duty manipulator in construction and ship building applications. A prototype arm has been designed and built based on the analysis and the comparative study of several types of hybrid drive mechanisms, the Stewart platform, and a wire drive mechanism. The tension of wire has to be maintained properly in the hybrid mechanism during its motion. The proposed hybrid arm is a kind of actuation-redundant mechanism and its internal force can be freely controlled. The proposed control algorithm is to give wires proper tension during its motion by exploiting the internal force, The required tension and cylinder force can be obtained by compensating each link position command based on its compliance. The repeatability tests show the effectiveness of the proposed algorithm in maintaining the overall stiffness of the arm.

The research aim is to apply locomotive robots to rescue tasks, such as searching for sufferers and removing obstacles to save sufferers. The paper discusses the exploitation of arm and leg integrated robots and basic experiments of infrared probing sensor, in the application of rescue tasks. First, the limb mechanism is introduced and discussed in the aspect of locomotion capability and stability in rough terrain of disaster area. Then, the probing sensor is evaluated in the aspect of its detection range and capability. Assuming the sensor is mounted on the tip of robot arm for probing, the probing algorithm is proposed to find quickly and locate precisely a sufferer. The basic experiments have been carried out using a parallel arm to confirm the applicability and the usefulness of the proposed rescue system.

In order to develop a high performance working robot, we design and develop a new robot based on the concept of "limb mechanism " for integration of legged locomotion and arm manipulation. The robot developed has six limbs which can be used for both locomotion and manipulation. The six limbs are set on vertices of regular hexagonal body so that this robot can have omnidirectional manipulability and mobility. We evaluate the stroke and the stability margin in all walking directions on six-legged and four-legged locomotion. As a result, this robot has higher omnidirectional mobility than conventional mechanisms.

This paper describes mobile manipulation of humanoid robots. A humanoid robot is a kind of integrated machines: two arm and two leg mechanism. It could be well applied to mobile manipulation in nonroutine task automation. The main objective of the mobile manipulation is to obtain versatile and efficient manipulation by the arms. In this respect the legs are required to assist the arms obtaining their high manipulability by changing step length and timing of step motion. Accordingly, the required motion of the legs in mobile manipulation is different from conventional biped locomotion. From this point of view, the relationship between manipulability of the arm and various leg motions is analyzed and evaluated by computer simulations.

A real-time robot arm control method for obstacle avoidance is proposed. If links are close to and approaching obstacles, the end-effector velocity is modified so that collision is avoided and the error between the desired and modified end-effector velocity can be minimized. For this purpose, a new matrix called the "collision Jacobian", which relates the approaching velocity of the links to the obstacles with the end-effector velocity, is proposed. Because the modified velocity can be calculated without an iterative algorithm, the proposed method is effective for real-time obstacle avoidance. This method is applied to collision avoidance between the links of a parallel arm.

A compact and economical 3-DOF finger module for micro manipulation is developed; it is designed for a two-finger micro manipulator which can manipulate micrometer-size objects dexterously like chopsticks. A 3-DOF parallel mechanism for this finger is proposed, and its inverse kinematics between the end effector position and the actuator displacements is formulated. The design parameters are determined so that its workspace volume may be as large as possible. A prototype using three piezo-electric actuators and two types of flexure joints, which are proposed for realizing a compact finger, is developed. The Jacobian matrix used for calculating the actuator displacements corresponding to the given end effector position is obtained by experiments. The repeatability and absolute positioning accuracy-about 2.0 /spl mu/m-of this prototype are evaluated.

A new hybrid cylinder/wire drive parallel arm (simply called "a hybrid arm") for manipulating heavy materials in construction and ship building works is proposed. Various hybrid arms with different combination of cylinders and wires are compared with the conventional Stewart platform and a multiwire drive mechanism. Their workspaces considering orientation are evaluated. The most suitable hybrid arm for heavy material handling is the mechanism with three cylinders, four wires, and one connecting rod between the cylinders and the end plate. This hybrid arm is modified into a mechanism with a variable length rod for the application of manipulating a precasting concrete board with a size of 3/spl times/6/spl times/0.2 m/sup 3/ and a weight of 10 t which is used in automatic building construction systems; a prototype of this arm has been designed and developed.

A method of the impedance control of a mobile manipulator with the stability to the external force acting on the workpiece is proposed. (1) It is assumed that the robot does not know the workpiece's desired trajectory and is commanded directly by the external force. (2) Different types of desired impedance are set to the workpiece and the vehicle; the workpiece behaves as a desired mass to the external force, and the vehicle responds to the input of its desired position as a typical linear second-order system. Thus, the manipulator responds to the fast change in the force and the vehicle responds to the slow change. (3) For the purpose of keeping the robot stable-preventing it from tumbling-to the external force, the vehicle's desired position is determined so that the robot's zero moment point may come nearest to the center of the supporting polygon. Accordingly, the vehicle moves toward the most stable position.

A method for the selection of a suitable type of robot manipulator for a given task using fuzzy reasoning is proposed. Various types of robot have different characteristics of the performances such as the shape and size of the workspace, the accuracy, the speed, and the weight capacity. Therefore, it is necessary to select the robot type with suitable performances for the given task in the design of the robot. The proposed method selects the most suitable robot type for the task, in the same way as a design expert. This method consists of the following steps; (1) The design expert's knowledge of the characteristics of the performances of each robot type is expressed as a fuzzy fact in the database. (2) The operator analyzes the task and obtains the performances required for it, pressed as fuzzy rules. (3) The degree of suitability for the task of each robot type is obtained from the knowledge concerning the performances of the robot type and the performances required for the task by fuzzy reasoning.

A behavior-based robot simulator 'JC-3' is described. A robot application is constructed in JC-3 using an interactive graphical 'agent-editor' where connections between sensors and actuators and between goals and actions are established. The agent-editor output is a 'meta-software', which can be transferred in to a real robot where a 'meta-software compiler' will produce a hardware level robot control program. The meta-software is a collection of behavior structures. A 'static' behavior selection mechanism is used with physical sensors/actuators and a 'dynamic' behavior selection mechanism developed by Maes (1991) is used when dealing with goals of the robot. Using the JC-3 simulator the operation of the meta-software can be simulated in a 3D computer graphics environment.>

A new robot simulator JC‐1 is used as a control software development tool in a project in progress where an intelligent wheelchair for a blind user is being developed. The intelligent wheelchair is planned to be able to fulfill simple symbolic commands like “follow wall” or “follow object” and using the JC‐1 simulator an evaluation team which includes e.g. the user, a rehabilitation engineer and a software engineer, can check control algorithms and user interface routines before constructing a real wheelchair prototype. The JC‐1 simulator models the environment using simplified boundary‐ representation where objects, robot sensors and actuators are presented as symbolic objects in the graphics data‐base of the simulator. In the JC‐1 simulator a robot controller under development controls the motion of the graphical model of the robot while simulator commands or other robot controllers can be used to control the movement of disturbing obstacles. Computer graphics animation and simulation help to find fundamental design errors at an early design stage and as this paper suggests, enable the user of the final product to take part in to the designing process of the robot controller. Benefits and difficulties of using computer graphics simulation in the wheelchair development process are discussed.

The development of a new 4800 bit/s data modem, based on real-time digital signal processing by program controlled microprocessors, is described. The modem is fully compatible with the CCITT Recommendations V.27 bis and V.27 ter. In the microprocessor modem, all the digital signals are processed by one general purpose microprocessor unit only and no hardware multiplier is employed. A series of processing cycle reduction tactics have allowed an off-the-shelf microprocessor to handle all the modem functions in a real-time environment. Particularly noteworthy, among these tactics, is the use of a decision feedback equalization algorithm. Numbers of multiplications, which are required for a conventional linear equalization, are shown to be obviated with the DFE algorithm. It is also shown that the DFE facilitates a certain timing phase control method. The microprocessor modem is extremely flexible because of its software controlled nature, and through programming it will provide a variety of additional functions.