This study proposes a method for high-performance model predictive control (MPC) by using a lifted bilinear model error model (MEM) based on the Koopman approach to compensate for errors in the prediction model. In MPC, more accurate prediction models can be expected to provide better control performance for the real plant. However, there often exist modeling errors in the prediction model, which may prevent MPC from achieving good performance. In this study, we identify the errors in the nominal model as an MEM, and formulate an MPC that integrates the nominal model and the MEM into an "error-compensated model" as a prediction model. We model the MEM with a lifted bilinear model that can represent nonlinear characteristics based on Koopman’s theory. In addition, an efficient linear MPC algorithm is constructed by linearizing the MEM while maintaining high prediction accuracy. Numerical simulations demonstrate the effectiveness of the proposed method.

We present a formulation for a linear temporal logic (LTL)-based task planning using the Koopman operator. The dynamics of nonlinear systems can be represented as linear systems by lifting them to a space of augmented states using the Koopman operator. On the other hand, the lifted linear system cannot capture the nonlinear effects of inputs, which appear in many robotic systems. Therefore, instead of a lifted linear system, we can consider representing control-affine bilinear systems. However, since the lifted bilinear systems are nonlinear, we need to solve nonlinear programming problems for trajectory optimization. This paper presents a methodology for the trajectory optimization problem of the lifted bilinear system. Using the mixed-integer convex approximation, we can solve the trajectory optimization problem of the lifted bilinear systems as a mixed-integer linear programming problem. This formulation allows us to solve LTL-based task planning problems for nonlinear systems. The effectiveness of the proposed method was confirmed by numerical simulations.

We propose a new optimization-based task and motion planning (TAMP) with signal temporal logic (STL) specifications for robotic sequential manipulation such as pick-and-place tasks. Given a high-level task specification, the TAMP problem is to plan a trajectory that satisfies the specification. This is, however, a challenging problem due to the difficulty of combining continuous motion planning and discrete task specifications. The optimization-based TAMP with temporal logic specifications is a promising method, but existing works use mixed integer problems (MIP) and do not scale well. To address this issue, in our approach, a new hybrid system model without discrete variables is introduced and combined with smooth approximation methods for STL. This allows the TAMP to be formulated as a nonlinear programming problem whose computational cost is significantly less than that of MIP. Furthermore, it is also possible to deal with nonlinear dynamics and geometric constraints represented by nonlinear functions. The effectiveness of the proposed method is demonstrated with both numerical experiments and a real robot.

We present a formulation for linear temporal logic (LTL)-based task planning of nonlinear dynamical systems. We consider pick-and-place task planning as a typical example of the planning task that can be modeled as a hybrid system that includes the states of robots and objects. LTL-based planning for hybrid systems is solved as a mixed-integer problem (MIP), especially a mixed-integer linear programming problem (MILP). Due to the formulation by the MILP, we could only deal with linear systems and linear constraints. In our proposed method, we apply a convex approximation to systems that have bilinear terms and quadratic terms in their dynamics. And we incorporate nonlinear systems into existing LTL-based planning as an MILP. We demonstrate the effectiveness through numerical simulations of a simple robot arm system and drone system.

In this paper, we propose a method for automatically generating object handling actions based on simple action definitions. The need to replace workers by robots is increasing, and, in fact, many research projects on robots have worked with simple motion definitions. Many applications are for mobile robots such as drones, however, and if such methods are applied directly to object handling, like a pick and place operation, it is necessary for humans to give detailed instructions. Hence, our contribution is to propose a model that simulates the real world with an augmented hybrid system that includes the states of objects. Then, it becomes possible to automatically generate robot motions with simple motion definitions and calculate them within a reasonable time. We demonstrate through computer simulation with a dual-arm robot that robot motions can be generated by simple definitions even if the environment changes to a certain degree.

We propose a method of subdividing robot tasks into new lower abstract tasks. The description of robot tasks in an abstract manner is effective for motion planning for complex tasks and teaching robot movements in various environments. However, a more efficient task description may be obtained by using a lower abstraction according to the work environment. We argue that a higher abstract task can be expressed as a new lower abstract subtasks by applying Grid-based Signal Temporal Inference (Grid-TLI). We show that a new task can be completed using the Signal Temporal Logic formula for each cluster. We demonstrated the efficiency of our method through computer simulations using a 2-D security robot task.

Biped robots are expected to have various activities in human society, and many biped robots have been developed. As the example, limit cycle walkers, can realize efficient walking using their own dynamics. However, they have a problem of weak robustness on uneven terrains. On the other hand, a technique for improving robustness by using output zeroing control with relative degree 3 has been proposed. In this paper, we derive the reference trajectory for the output function and holonomic constraints used when applying output zeroing control with relative degree 3 by direct collocation method which is a method of a trajectory optimization. We show that they walk by using the derived reference output function and holonomic constraints and improve the robustness on uneven terrain.

For underactuated bipedal robots, it is important to compensate disturbances which affects the zero dynamics to realize a stable locomotion when we use output zeroing controllers. In order to deal with such disturbances, this paper presents a framework of a periodic trajectory planning and a robust output zeroing controller using a disturbance model learned by Gaussian process regression (GPR). In particular, we propose a control method considering the modeling uncertainty of the disturbance model by using a variance information of GPR model. We show the effectiveness of the proposed method through a numerical simulation of walking control of an underactuated robot model affected by an external force.

This paper addresses robust filtering for nonlinear systems with parameter uncertainties. We developed a new robust unscented Kalman filter (RUKF) which doesn't require calculating Jacobian matrix by using Unscented Statistical Linearization to consider the influence of parameter uncertainties of covariance matrices. The RUKF is more accurate than conventional UKF when the systems have parameter uncertainties. However, when there is no parameter uncertainty, estimation accuracy of the RUKF may be inferior to that of the UKF. Then, we also developed adaptive RUKF (ARUKF) by introducing an adaptive scheme into RUKF to automatically tune the influence of parameter uncertainties. The validity of the proposed methods is illustrated by Monte Carlo simulations.

In this paper, we propose a novel method for fast limit cycle walking using active control of a wobbling mass. Limit cycle walkers achieving energy-efficient walking have been developed in the last decade. Many researchers have recently studied methods for improving walking speed of limit cycle walkers. In human walking, humans swing their arms according to walking phases and the motion is a regularly symmetric motion about the torso. We consider that this motion is an active up-and-down motion for a mass and improves biped walking speed. We numerically and mathematically show that a biped robot achieves fast limit cycle walking by the proposed method.

In many cases, outliers are contained in sensor signals, and these deteriorate performances of control systems, e.g., UAV and UGV using non-contact sensors. Many reduction methods of the outliers have been proposed. One of the methods is robust Kalman filter (RKF) via ℓ1regression. The method is easy to implement and compute due to a simple structure and convex optimization problem, so the method attracts many attentions. However, parameters of the method are designed by heuristic methods. In this paper, we propose a design method of RKF via ℓ1regression. We show that statistics of Gaussian noise determine the parameters of RKF, and we can design the parameters systematically. Then, we apply the method to a velocity estimation and control of a two-wheeled vehicle with outliers. Effectiveness is demonstrated by some numerical simulations.

In this paper, an experimental validation of a new balancer configuration for stabilizing of an unmanned bicycle is presented. The balancer can be configured as a flywheel mode or a balancer mode by shifting the center of gravity of the balancer. This balancer configuration is changed according to the situation of the bicycle system, which corresponds to the change of the dimension of the system. The balancer is configured as a flywheel, when disturbances to the system are large, and it will switch to the balancer when the position of the center of the gravity should be shifted. Stabilizing bicycle with the flywheel has better performance than the balancer but it cannot control to shift the bicycle angle to track the desired value, unlike the balancer which can do this motion. The balancing controller is derived based on an output-zeroing controller. Numerical simulation and experimental results are shown to verify the effectiveness of the proposed control strategy.

Since unmanned bike robots have high mobility and do not require wide contact space to the ground, it is expected that they will be used as one kind of the robots working in disaster areas and/or in the mountains. We are developing one of the unmanned bike robot systems with a balancer and it can do a wheelie and move to track the path in the ground plane. In this paper, we propose a control strategy to perform an acrobatic turn with wheelie motion, which can be quick and require minimum contact space for a bicycle by using nonlinear control based on the output-zeroing controller. The dynamic models of the bicycle with the balancer are derived from Lagrangian's equations and they are combined by Lagrange's multiplier according to nonholonomic and holonomic constraints between subsystems. The effectiveness of the proposed method is shown by several numerical simulations using a detail model of a bicycle.

In this paper, we propose a control algorithm for stabilizing of an unmanned bicycle at zero speed by using a nonlinear control based on an output-zeroing controller. The simplified model of the bicycle with the balancer is derived from Lagrangian and nonholonomic constraints with respect to translation and rotation relative to the ground plane. We derived a controller using a steering torque and a balancer torque to stabilize the bicycle at zero linear velocity. The output-zeroing controller is designed by using the angular momentum of two-link system and by adding the effect of steering angle to the derivative of the angular momentum. Numerical simulation and experimental results are shown to verify the effectiveness of the proposed control strategy.

Bucky gel actuator is a novel electro-active polymer (EAP), which is a low-voltage driven dry soft actuator. In addition, the bucky gel device generates electromotive force when bending, and then it also can be used as a sensor. Its device has a bimorph structure with polymer-supported bucky gel electrodes and a polymer-supported ionic gel electrolyte. It can be fabricated by layer-by-layer casting, to form any shape easily. In this paper, we demonstrate an automatic fabrication method of the bucky gel devices based on a printing method. By using a dispensing machine, we construct the printing system, and manual forming process is replaced with automatic printing. We investigate the printing of complicated shapes and 3D electrode pattern through experiments.

Advances made in the research of IPMC (ionic polymer metal composite) actuators have shown that this technology is highly suitable for both minituarization, and use in environments that may prohibit the use of conventional actuation devices, such as submerged in a fluid. These characteristics indicate the compositepsilas suitability for implementation by small-scale aquatic vessels, such as those that operate within blood-streams to record and transmit biological data or interact with the blood to treat a medical condition. In order to develop such a robot, a suitable control system must be developed that allows for optimization of the IPMC motion to maximise thrust, given constantly changing conditions of the surrounding environment and parameters of the robot itself. This paper seeks to develop such a control system, first by developing a propulsion model for the robot, and then uses Extremum-seeking feedback control to optimise the swimming mode, with the results verified experimentally.

In this paper, we consider the effects of feet in various convex shapes on the performance of underactuated passive dynamic walking. We first derive formula for calculating virtual ankle-joint torque and a performance index of dissipated mechanical energy for a convex foot shape model with general foot shape parameterization. Secondly, using the foot shape determined by a 2nd Bezier curve with which a form can be controlled easily, we calculate a value of the virtual ankle-joint torque and the performance index of dissipated mechanical energy to verify effects of change in foot shape. Furthermore, relationship between the foot shapes and the walking speeds are clarified by a numerical simulation. Finally, we propose a method to design a convex foot shape that attains a desired virtual ankle-joint torque and verify an improvement of the walking speed by a numerical simulation with the foot shape that is designed by the proposed method. We believe that the proposed method will be applied to design effective active ankle-joint torque and/or to design a foot shape for biped robots.

Bucky gel actuator is a novel electro-active polymer (EAP), which is a low-voltage driven dry soft actuator. Its device has a bimorph structure with polymer-supported bucky gel electrodes and a polymer-supported ionic gel electrolyte. It can be fabricated by layer-by-layer casting, to form any shape easily. In addition, the bucky gel device generates electromotive force when bending, and then it also can be used as a sensor. Since sensor and actuator functions exist in a same device, flexible and miniature integrated actuator-sensor systems for soft robotics can be constructed easily. In this study, we conduct some experiments to verify the possibility of the bucky gel actuator/sensor. Feedback controls of the actuator are demonstrated and the characteristics of the sensor are investigated. By utilizing both functions of the actuator and the sensor, feedback control based on the sensor signal is demonstrated.

We constructed a snake-like swimming robot using IPMC actuator, and verified swimming motion based on numerical simulation and experiments. In applying periodic inputs with appropriate frequency and phase shift, the snake-like robot is capable of smooth propulsion. It is known that IPMC has a sensor function that IPMC films generate electromotive voltage when bending or being deformed. By using the sensor function into the snake-like robot, it is considered that autonomous propulsive motion can be realized by feedback of the sensor signal. In this paper, we consider the autonomous locomotion of the snakelike swimming robot with IPMC actuator/sensor, and verify the realization of swimming motion by feedback of the sensor signal. Furthermore, the efficiency of the autonomous locomotion is investigated

We are studying about robotic application of ionic polymer-metal composite (IPMC). The characteristics of IPMC highly depend on the type of counter-ions, and it is considered that the performance of the actuators can be improved by combining the actuators with several types of counter-ions and applying an integrated control. IPMC has also a sensor function, as the IPMC film generates electromotive force when it is deformed. It has possibility to be integrated into IPMC actuator with soft actuation. In this paper, we consider an integrated design of IPMC actuator/sensor, and investigate a control of the combined IPMC actuators using Hinfincontrol and the construction of IPMC sensor system

In this paper, trajectory tracking and balancing control for autonomous bicycles with a balancer are discussed. In the proposed control method, an input-output linearization is applied for trajectory tracking control and a nonlinear stabilizing control is used for the balancing control. Even though control methods are designed independently, it is shown by several numerical simulations and experiments using a detail model and a real electric motor bike that the stability of the bicycles is ensured with the method even when the desired speed is zero and trajectory tracking to desired ones are achieved

In this paper, an extension of nonlinear receding horizon control (RHC) or model predictive control (MFC) for switched systems with state discontinuity is proposed, and it is applied for landing control using a simplified humanoid model. The proposed control method is based on continuation method and GMRES method which can be applied online to mechanical systems- The validity of the method is demonstrated by numerical simulations.

Ionic polymer metal composite (IPMC) is one of the most promising EAF actuators for applications, and slave good property of response and durability. The characteristics of IPMC materials depend on a type of counter ion. In applying to mechanical systems such as a robot, there exist possibilities to change the properties of the dynamics by changing the counter ions according to environment or purpose adequately. In this paper, we consider swimming of a snake-like robot with IPMC actuator, and demonstrate a smooth swimming motion. Then, we also verify the doping effects by experiments.

Principal mechanisms of passive dynamic walking are studied from the mechanical energy point of view, and novel gait generation and control methods based on passive dynamic walking are proposed. First, a unified property of passive dynamic walking is derived, which shows that the walking system's mechanical energy increases proportionally with respect to the position of the system's center of mass. This yields an interesting indeterminate equation that determines the relation between the system's control torques and its center of mass. By solving this indeterminate equation for the control torque, active dynamic walking on a level can then be realized. In addition, the applications to the robust energy referenced control are discussed. The effectiveness and control performances of the proposed methods have been investigated through numerical simulations.

This paper studies the dynamic principles of passive dynamic walking and proposes novel gait generation and control methods based on it. The authors have clarified a unified property of passive dynamic walking which shows that the walking system's mechanical energy increases proportionally with respect to the position of system's center of mass. Following this, the gait generation problem yields solutions of an indeterminate equation. By solving it for the control torque, active dynamic walking on a level can then be realized. In this paper, we first discuss the solutions and consider the unification of the previous gait generation methods from a variable virtual gravity point of view. Second, its applications to a kneed biped system considering ZMP condition and robust energy referenced control are discussed. The effectiveness of the proposed methods have been investigated through numerical simulations.

This paper studies modeling and bio-mimetic control of a 3D 8-dof whole arm cooperative manipulation system using sensitive skin. A sphere is considered here as a manipulated object. The control law is designed based on integration of voluntary and reflex movements considering the system's redundancy. The voluntary task for holding the object is realized by impedance control at the four contact points with the object using the contact force information from the sensitive skin. The reflection on the other hand is introduced as a regulation problem of the direction between the points of end-effectors and elbows. The solution for the redundant control is formulated and derived from the optimization point of view. The validity of the proposed method is investigated by numerical simulations.

The authors have clarified the mechanism of passive dynamic walking from the mechanical energy point of view, and reported its basic results. This paper then considers the generalization and unification of dynamic gait generation methods by introducing variable virtual gravity concept and some solution formulas as well as essential mechanical energy orbits. As two leading methods, energy tracking control and virtual passive dynamic walking are considered, and we analyze the control performances of robust stability and energy-efficiency criterions by numerical simulations. Finally we discuss the application possibility of the methods to actual walking machines from the ZMP point of view.

This paper discusses a formation control of a multiple mobile robot system (MMRS) called super Mechano colony (SMC). First, we introduce the SMC system composed of a mother ship and many agents as a prototype of MMRS. We propose a control method for formation control of child robots using multiple coordinate systems, i.e., physical coordinate system and shape coordinate system. The properties of the combined control method are shown by numerical simulations and an experiment.

This paper proposes novel energy-based gait generation and control methods for biped robots based on an analysis of passive dynamic walking. First, we discuss the essence of dynamic walking using a passive walker on a gentle slope from the mechanical energy point of view. Second, we propose a simple and effective gait-generation method, which imitates the energy behavior in every walking cycle considering the zero-moment point condition and other factors of the active walker. The control strategy is formed by taking into account the features of mechanical energy dissipation and restoration. Following the proposed method, the robot can exhibit a natural and reasonable walk on a level ground without any gait planning and design in advance. The effectiveness of the method is examined through numerical simulations and experiments.

The COE acrobat robot, called SMB (Super Mechano-Boy), is considered as a model of a gymnast with a horizontal bar. Our final objective is to perform skillful motions with the system same as a gymnast. In this paper, we consider the landing control after actions on the horizontal bar using a linear complementarity problem. We also consider a parameter estimation using the relationship between Lagrange multiplier and sensitivity of the constrained system.

In this paper, we propose a winding control technique using a physical index of horizontal constraint force for a 3D snake-like robot, and it is shown that a winding motion of the robot can be realized with small joint torque. If it approaches a target point, it is necessary to raise the head and to work like a manipulator. Therefore, a control method of the head configuration using a criterion function, which can be used in both redundant and insufficient number of link cases is proposed. In order to show the validity of the proposed methods, we constructed a snake like robot called SMA. Using the experimental system, we show that the winding pattern with which the robot can avoid singular postures is generated automatically, and head position and head orientation can be controlled properly.

This paper discusses a formation control of a multiple mobile robot system (MMRS) called super mechano-colony (SMC). First, we describe the SMC system composed of a mother ship and many agents as a prototype of MMRS. Second, we propose a cooperative transportation method of the mother ship with multiple agents, and the properties of the proposed method are analyzed using an experimental system.

Unlike the present manipulator control technologies that operate objects only by the robots' end-effectors, human beings can perform whole body manipulation flexibly and easily. Bio-mimetic research of such skillful human motor behavior is important not only for deeper understanding of human sensations and nervous control functions but also for developing of higher level robots. In this paper, we first formulate the basic model of multipoints whole body interaction between a robot manipulator and its object. We then study three control approaches by considering the limitations of force feedback, the complexity of control algorithms. As an example, we consider a 2-link planar manipulator that operates a circle object with dynamic arm friction. We show a computer simulation algorithm, and compare the results of each control methods, numerically.

The Super Mechano Boy (SMB), a nine-link eight-actuator mechanical system is considered as a model of a gymnast with a horizontal bar. This paper deals with a landing control of SMB as the final motion of a performance of various skillful motions such as swinging from pendant state, forward upward circling, handstand on the horizontal bar, giant swing, flying off, somersault. This motion is very important for the completion of the series of the gymnastics motions with horizontal bar. The proposed control method consists of several control algorithms and the control is switched according to contact conditions. Numerical simulations verify the effectiveness of the proposed control methods.

In this paper, we propose a control algorithm for the problem of stabilization of Acrobat Robot in upright position on a horizontal bar, in an actual experimental environment. The dynamics of the closed loop is designed to match a stable closed loop dynamics around the equilibrium. Moreover, we apply an iterative learning control in order to deal with modeling errors. The validity of the proposed methods is shown by numerical simulations and experiments.

This paper proposes a novel energy-based control law for biped robots based on an analysis of passive dynamic walking. Firstly we discuss the essence of dynamic walking using a passive walker on a gentle slope. In the second, we propose a simple and effective control law which imitates the energy behavior in every cycle considering the ZMP condition and other factors of the active walker. The control strategy is formed by the feature of mechanical energy dissipation and restoration. By the effect of the proposed method, the robot can exhibit natural and reasonable walk on a level ground without any gait design in advance. The validity of the proposed method is examined by numerical simulations and experiments.

In our previous works (2000), we have proposed "virtual passive dynamic walking" utilizing modified gravity condition with virtual gravity field. The virtual passive walking motion critically depends on the physical parameters and the steady walking pattern is not easily obtained without suitable physical parameters. In this paper we propose a more generalized method of virtual passive walk and a virtual passivity mimicking control law. With the effect of the control laws, we can generate the steady walking pattern even if the physical parameters are not suitable. We call the walking pattern generated by the control methods as "extended virtual passive dynamic walking". The validity of the proposed method is examined by numerical simulations and tested by a prototype experimental machine.

We propose an adaptive generation method of desired velocity field for leader-follower type cooperative mobile robots with decentralized passive velocity field control (PVFC) which is a decentralized control algorithm of multiple robots handling a common object in coordination. The proposed control method for cooperative mobile robots is constructed by extending the PVFC. This research is different from the previous work in which a common desired velocity field for cooperative PVFC and all cooperative mobile robots was only following the same desired velocity field using the proposed method supervisor can easily specify the behavior of the mobile robots. The stability and boundedness of the resultant system with the proposed control algorithm is also guaranteed. Finally, the proposed control algorithm is examined by computer simulations for cooperative tasks with two mobile robots, and the results illustrate the validity of the proposed control algorithm.

The focus of this work is to generate and realize automatically an ideal periodic gait of walking robots which depends on properties of the system and an environment. In conventional works, a robot walking are realized by a tracking control for a predetermined desired trajectory. A necessary control for walking robots is not to track a desired trajectory but to generate a suitable trajectory according to changes of the environment. In order to realize this function, two methods will be discussed in this paper. The first one is the control method to realize a suitable steady periodic motion. The method will be called 'phase synchronous control,' which creates a stable limit cycle for the system which has an unstable one. The second one is the algorithm which is called 'desired state optimization' and modifies the motion to an optimal one, that a criterion function is optimized. Using this algorithm, if the environment of the system is changed, an ideal motion for the environment is automatically realized. The validity of the proposed method will be examined by numerical simulations.

In our previous works (2000), we proposed some system augmentation methods for dynamic bipedal walking in order to realize variable walking patterns in real-time, however, the robust performance of the methods were discussed. Based on the observation we propose a new coupling control law considering the flywheel effect for robustness. In this paper the validity of the methods is analyzed and investigated by numerical simulations and experiments.

In our previous works, we have proposed "virtual passive dynamic walking" with virtual gravity for biped robots in order to realize active walking on level ground without any gait design in advance. In this paper, we discuss some control problems of a kneed biped robot and propose "modified compass-like virtual passive dynamic walking" with active knee-lock algorithms in order to avoid the "foot scuffing" problem during the single support phase. Furthermore, a virtual coupling control law is proposed which can realize a variable walking pattern with respect to the robot's energy levels. By the effect of the control law, the robot, which is a hybrid dynamical system, can be regarded as a passive system which does not include any collisions, and a variable walking pattern can be realized without loss of the properties of a virtual passive walk. The validity of the proposed methods has been examined by numerical simulations.

The study of bipedal walking in the framework of humanoid robot is a recent active research area. In this paper, we apply passive velocity field control to the control of a biped walking robot which walks on the level ground by actuators. Using this method, we can change the walking speed easily by modifying a virtual energy. The validity of the proposed method is demonstrated by numerical simulations.

It has been shown that a simplest walker with suitable parameter choice can walk down a gentle slope without any control forces and generate its steady walking pattern utilizing gravity effect automatically. On the floor, however, the robot cannot exhibit passive walk, so any application methods of passive walk to active walker on the horizontal floor has not been studied yet. In this paper we introduce "virtual passive dynamic walking" with virtual gravity field which acts as a driving force for the biped robot. The robot can walk on the floor without any control torque except virtual gravity effect. Since the modified gravity field seems to be very close to real condition, the generated walking pattern seems to be natural. Further, multi-pattern walking with respect to energy level is proposed. With the proposed method, safety and energy-effective control of biped walking robot can be realized.

We have proposed a decentralized control method based on passive velocity field control (PVFC) in previous works (1997, 1998). However, the feedback was localized and the desired velocity field was given by a central controller. The geometry cooperative multiple mobile robot system whose subsystem is under nonholonomic constraints and which conveys a common rigid object in a horizontal plain was proposed. In this paper, we propose a method to generate the desired velocity field for cooperative mobile robots with decentralized PVFC. The proposed control method for cooperative mobile robots is constructed by extending the PVFC and ensures the stability and boundedness using projection algorithm. Finally, the efficiency of the proposed method is examined by computer simulations for cooperative tasks with two manipulators.

Traditionally, tasks for a robotic system are specified by a desired timed trajectory. There, however, are many tasks in which the desired motions are specified by the state of system rather than time, such as contour following tasks. For such tasks, passive velocity field control (PVFC) has been proposed and the geometry of the controlled systems was analyzed. In this paper, a method to apply the PVFC to cooperative multiple mobile robotic systems whose sub-system is under nonholonomic constraints and which convey a common rigid object in a horizontal plane is proposed, and the effectiveness of the control method is demonstrated by several numerical simulations.

Traditionally, tasks for a manipulator are specified by a desired timed trajectory. There, however, are many tasks in which the desired motions are specified by the state of system rather than time, such as contour following tasks. For such tasks, passive velocity field control (PVFC) has been proposed and the geometry of the controlled systems was analyzed. In this paper, a method to extend the PVFC to cooperative multiple manipulators is proposed, and the effectiveness of the control method is demonstrated by numerical simulations, and some properties are shown.

Many researchers have studied bilateral master-slave teleoperator systems, especially since Anderson and Spong (1989) proposed a novel and simple method to overcome the instability due to transmission delays. In this paper we propose a bilateral master-slave manipulator system in which the slave impedance can be adjusted by the operator in a bilateral fashion. The stability of the system for the time delay is also discussed, and the effectiveness of the system is shown by experiments.

This paper discusses the compliance control of an ultrasonic motor powered prosthetic forearm which utilizes cutaneously measured electromyogram (EMG) signals sensed with the electrodes over the muscles as means of detecting motor commands sent by the central nervous system (CNS). Compliance control of the artificial limb was studied by implementing the bilinear model of the forearm and hand. This model emphasizes the role of the visco-elastic properties of the musculo-skeletal system of the actual limb in controlling its net configuration and movement. The flexor and extensor muscles extending over a joint influence the total joint impedance and determine the equilibrium position of the joint. Relaxing both flexor and extensor muscles makes the joint compliant to external forces, while activating both muscles increases the impedance of the joint.>

In this paper we discuss pattern generations and switching for robot manipulators to perform tasks under qualitative changes of the dynamic environment. The approach is to compose continuous type artificial neural elements as an oscillator based on mutual entrainment and generate trajectories for the manipulators. Using the neural oscillator, juggling control of manipulators is considered as a concrete task, and a method to alternate patterns of the trajectories according to the change of the desired value and environment is proposed. Some numerical examples show the efficiency of the proposed method.>

In this paper we propose a technique for tele-virtual reality of dynamic mechanical models, which means that one dynamic mechanical model can be shared by peoples in distant places. Since a stabil- ity issue due to time delays arises in the system, we employed a scattering technique developed for a tele- operator system and a kind of passive adaptive con- trollers. Furthermore, restrictions due to a simple digi- tal implementation of the scattering transformation are discussed and some conditions for stability are shown. The proposed method is applied to a remote tug of war system and the effectiveness is verified.

The authors propose a parallel Newton-Euler algorithm for calculating the inverse dynamics of manipulators whose computational time is independent of the number of links. The algorithm consists of two paths: a forward path for calculating a kinematic chain, i.e., linear velocities, linear accelerations, etc.; and a backward path for determining a dynamic chain, i.e., forces and moments. In order to determine each moment or force perfectly, the paths must be tracked sequentially. Complete parallel implementation of the Newton-Euler algorithm with data buffering is proposed for constructing a control scheme whose control period can be reduced drastically and is independent of the number of links. Delays due to the data buffering are suppressed by a one-step-ahead prediction using a linear model. The effectiveness of the proposed algorithm is demonstrated by extensive numerical simulations.>

We present a new algorithm that generates a suitable input for a manipulator to track the desired predetermined trajectory after repeating trials. It is ensured that the error between the desired trajectory and that of the manipulator becomes zero in a certain sense as the number of trials approaches infinite. In the proposed algorithm a kind of dual systems is used for recurrsively making new input and that system can be simply designed. The proposed algorithm is based on functional analysis.