So far, multiple LCD monitors and joysticks have been used for remote operation of excavators while it has low work efficiency. This is because it is difficult for the operator to recognize the state of the excavator and its surrounding environment. We have developed a semi-autonomous control system which consists of autonomy (attractor based dynamical system) and human action (admittance control). On the other hand, excavation tasks require the task selection. In this paper, we propose a nonlinear dynamical system with attractor with stagnation and bifurcation. The stagnation of the attractor is designed as a negative divergence vector field that converges to a point on the trajectory. A stagnation is placed at a bifurcation point of the trajectory, and the operator selects the next task by adding a force to the leader system.

Throwing an object by a powered robot system is of great importance in unmanned environments. In this paper, we consider the problem of throwing a point-mass object to minimize uncertainty in the object's landing position, given uncertainty in (1) the robot's initial configuration and (2) friction at the joints. Our analysis assumes that the robot's throw is executed using open-loop torque commands, and it relies on the linearized sensitivities of (a) landing location with respect to release state, (b) release state with respect to initial robot configuration and (c) joint friction. Moreover, the effectiveness of the proposed method is evaluated by Monte-Carlo simulations.

Catching is one of the most complex tasks in the area of dynamic manipulation. Exact information on the position and orientation of a rigid object is crucial in order to accomplish manipulation tasks. Both motion planner and control strategy use these data to achieve the desired contact of a predefined surface with a nonprehensile end-effector, e.g. flat plate. This paper presents a multi-level approach for robust task planning and execution for planar catching of rigid bodies. On the top level the choice of the best catching strategy is made. Different catching actions are introduced and classified based on relative translational and rotational velocities between the end-effector and the object. A motion planner is implemented on the middle level that produces smooth motion trajectories depending on the chosen strategy. Yet, some uncertainties occur during task execution due to sensory data, trajectory tracking and unmodeled dynamics. Therefore, a robust tracking control is implemented on the bottom level to guarantee task execution in presence of uncertainty in robot parameters. A sustainable framework is being used taking the dynamics of the robot, the object and the environment into account to create a consistent and versatile catching system.

This paper proposes an off-line periodic motion pattern design method using dimensional reduction. A human periodic motion is measured by a motion capture system, and it is projected onto a low dimensional space based on principal component analysis. The low dimensional motion pattern is modified, so that the high dimensional motion pattern satisfies the motion conditions, dynamical consistency and joint angle and torque limitations. The proposed method is applied to the motion pattern design of the planar bipedal robot. The moon-walk performed by a human is transformed to the robot motion. In this case, the motion conditions are the kinematic closed loop condition and the ground contact states of foot links. The floor reaction force condition and the satisfaction of the motion equation are given for dynamical consistency.

For the effective use of motor power, an appropriate gear ratio has to be selected according to the robot task and motion. Because a jumping robot, in particular, requires both high torque and high velocity properties through the motion, a varying gear ratio is necessary. Moreover, it has to be optimally designed and realized. In this paper, we design a jumping robot with a non-circular gear that changes the gear ratio through the motion for the higher jumping. Based on statics, the gear ratio is optimized and change of the gear ratio is obtained by a simulation-based design considering the robot dynamics. So far, we have developed a design method of no-circular gear, and its effectiveness was evaluated by simulation. In this paper, a jumping robot is prototyped, and the effectiveness is evaluated by experiment containing the robustness for the perturbation of robot parameters.

In this paper, we develop a design method of nonlinear profile of gear ratio to utilize a DC servo motor effectively for a jumping robot. Because the larger ground force yields the higher kinetic energy of the robot body, the optimal gear ratio is obtained by the maximization of the ground force from statics point of view. Moreover, the varying gear ratio during the jump motion is obtained through a simulation which connects statics-based optimization and robot dynamics. A non-circular gear is synthesized which realizes the obtained optimal varying gear ratio. The effectiveness of the proposed method is evaluated by simulations.

In this paper, we consider a robot with nonlinear springs located at each joints and acting in parallel with the actuators. We propose a method to simultaneously design the trajectory of the robot and the force/torque profiles of the springs for an optimal compensation of the gravity and inertial forces. First, we express the trajectory and force/torque profiles of the springs as a Hermite interpolation of a finite number of nodes, then we derive a closed-form solution of the optimal spring design as a function of the trajectory. As a consequence, the initial optimization problem is reduced to a trajectory optimization problem, solved with a numeric algorithm. We show an example of optimal design for a 3-Degree Of Freedom (DOF) serial manipulator. Finally, we show that the nonlinear springs calculated for this manipulator can be technically realized by a non-circular cable spool mechanism.

In the densely-populated urban areas, pedestrian flows often cross each other and congestion occurs. It may cause discomfort feeling or pedestrian accidents. In order to reduce the congestion or the risk of accidents, it is required to control swarm flows of pedestrian. This paper proposes an implicit control method of the crossing pedestrian flows. Pedestrian flow is modeled with the continuum fluid model and its congestion degree is calculated as the fluid density. From a simulation of the crossing flows with the continuum model, it is verified that diagonal stripe pattern of the congestion degree emerges. Moreover, the authors propose an implicit control method to improve average flow velocity by moving guides. Focusing on periodic phenomenon of the crossing flows, we investigate the relationship between its temporal and spatial frequency and a periodic motion of guides. From this relationship, a control method based on the temporal and spatial frequency is proposed.

It is an important issue to make a disaster reduction plans for overcrowded population in the urban cities. In this paper, we focus on evacuation guidance to prevent the damage from spreading. The personal navigation system cannot deal with evacuation guidance for the human crowd with large numbers of individuals because of time constraints and extraordinary communication error. An implicit guidance based on dynamical characteristic of swarm behavior is efficient and effective with a few guidance operators. We propose a modeling and control method of swarm based on vector field. The evacuee behavior model contains intention of evacuation, field of view, collision avoidance and evacuee group, which are represented by vector field. The guidance operator model contains indicating direction. By giving the desired vector field that indicates the safe route for evacuation, the position of guidance operators are optimally distributed. Moreover, the number of guidance operators is minimized based on the contribution index. The proposed modeling and control method is applied to the swarm robot and the effectiveness is evaluated by the experiments.

In an exhibition space, it is possible to control human flow implicitly by changing a layout of exhibits. The objectives of this paper are the layout optimization of exhibits to reduce congestion and the amenity space design. For these purposes, macro modeling of human swarm behavior and the optimization method of a layout of exhibits are required. So far, human swarm behavior has been modeled by two-dimensional vector field and individual behavior is represented by dynamics including collision avoidance vector of individuals. In this paper, we extend the human model to multi-dimensional dynamics in order to represent individual characteristics in measured data and visitors' stopping to view exhibits. In addition, a layout of exhibits is optimized based on the proposed model by minimizing collision avoidance vector. The proposed method is verified by simulations and experiments using swarm robots which consist of autonomous mobile robots and radio controlled robots. The results show that the comfortable exhibition space is designed.

In this paper we present a cable mechanism which realizes a nonlinear rotational spring from a linear translational spring. The spring is pulled by a cable wound around a non-circular spool, which is rigidly attached to the joint. The non-circular shape of the spool induces a nonlinear relationship between its angular position and the torque created by the tension of the cable. Depending on the shape of the spool, various torque profiles can be realized. We show that for a given nonlinear torque profile, there is a closed-form solution of the shape of the spool which synthesizes this function. In a first part, we present the geometry of the problem. In a second part, we derive the methodology to calculate the shape of the spool to synthesize a prescribed torque profile. In the last part, we verify the design methodology by experiments with three different spools realizing a constant force spring, an exponential softening spring and a cubic polynomial spring. We discuss the possible sources of errors between the theoretical and experimental results.

To prevent the human injury or breakage of the robot caused by interaction or collision with the robot and its environment, it is an important issue to introduce robot softness. However, because not only softness but also stiffness is required for precise task execution, the simultaneous realization of softness and stiffness using time varying stiffness is required in the real environment. We focus on the robot motion, and propose a realization method of time varying stiffness using robot motion and nonlinear passive stiffness. To realize the purpose-designed property of the time dependent stiffness, the nonlinear property of the passive stiffness has to be arbitrary designed considering the robot dynamics. In this paper, we propose the nonlinear property design method of passive stiffness based on kineto-statics with closed kinematic chain. The mechanism is synthesized based on the optimization of the generative force or torque, and purpose-designed stiffness is realized. The proposed method is evaluated by simulations and experiments using the prototype of the landing mechanism.

Skill or motion transfer from someone to other persons is always required for dance teaching, rehabilitation, sports and so on. For teaching or transfer of motion, a dance notation and display of sequence of motion are often used effectively. However, these contain only the instantaneous postures of motion or professional subjective sense, it is not easy for beginners to understand the dynamical knack of motion. In this paper, we propose “pseudo-reference” that is a virtual target posture in the human motion. The pseudo-reference is developed based on the modeling of the human motion by the attractor design method which realizes an autonomous system. By comparing the nonlinear controller with conventional control systems (1DOF and 2DOF control system), the pseudo-reference is obtained as an embodiment of the implicit reference. The proposed method is performed with the inverted pendulum system and the tap dancing robot, and the validity and feasibility for motion transfer of the pseudo-reference are evaluated.

Robot control systems consist of a feedback controller and reference motion pattern. They are designed based on the robot dynamics and coupled with each other, and it requires lots of calculation to obtain them. So far, we have proposed controller design method based on orbit attractor of nonlinear dynamics. Because the controller yields one motion for one robot, we can assume that the controller includes information of motion and body elements. If those elements can be decomposed from the controller, a new controller can be easily designed by the combination of these elements. So in this paper, we propose the motion and body elements design method with Lagrange's method of undetermined multipliers based on robot dynamics, and combination design method of a new controller using these elements. The effectiveness of the proposed method is evaluated by experiments with tapping dance robots.

When hyper redundant robots are used in complex and unpredictable environments such as human living space, they should deal with various contact conditions between surrounding objects. Robots thus should plan and optimize not only applying force to the object but also its distribution among contact area. This paper defines the ability to optimize stiffness distribution of a number of contact points as "flexibility" and proposes elastic closed-loop mechanism which has a serial chain of revolute joints with torsion coil springs as a lightweight and supple hyper redundant mechanism. Output stiffness is formulated based on the minimization of potential energy, the balancing of internal force and the velocity constraint to construct a closed-loop mechanism. Joint input to obtain both the desired stiffness distribution and desired output position simultaneously is derived from partial derivative of the output stiffness and compensation by a learning control scheme. Motion control experiments with a 10R elastic closed-loop robot demonstrate the effectiveness of the proposed control scheme.

To introduce a passive compliant mechanism for robot joints is an effective way for impact absorption. However, because robot joints also require high torque transmission characteristic, the simultaneous implementation of stiffness and softness is a significant issue. In this paper, we develop a torque transmission mechanism with nonlinear passive stiffness that realizes from zero to extremely high stiffness based on mechanical singularity. The analysis of nonlinear stiffness is established and the experimental evaluation is shown. A four-legged robot with the proposed mechanism is designed and the effectiveness of high nonlinearity of the proposed mechanism is shown by simulation.

The human communication exists in various situations of our daily life. For human-robot communication or robot-robot communication, it is useful to design a communication model based on communication principal that is an entrainment phenomenon of nonlinear dynamics. In this paper, we focus on the robot motion synchronization for robot-robot communication. The robots are controlled to be entrained to an orbit attractor that corresponds to a robot motion. By exchanging the state variables of each robot, the robots are controlled to entrain one attractor that is possible for both robots and synchronize each other. The results of this paper represent the communication principal by an entrainment phenomenon of nonlinear dynamics.

This paper describes a new method to utilize redundancy of hyper redundant robots. In order to use redundancy effectively, the contribution of all actuators for the achievement of the target motions and capability for unpredictable target motions in the future should be considered. From this point of view, two evaluation indices, the movability index of each joint and the assistability index for the target motions are proposed. These indices are formulated with the angle and amplitude distribution of the column vectors of Jacobian matrices of each joint, including the end-effector. Then joint input to optimize these indices simultaneously are derived based on the improved gradient projection method. Motion control simulations and experiments with a planar 10R serial manipulator revealed the effectiveness of the proposed method.

The human motions are generated through the interaction between the body and its environments. The information processing system defines the current motion using the signal feedback of the body state and environments. The motion pattern dose not exits a priori but emerges as the result of the entrainment phenomenon for the dynamics of the information processing, the human body and its environments. In this paper, based on the dynamics-based information processing system, we propose the motion emergency system design method for a humanoid robot designing a dynamical system that has an attractor considering the robot body dynamics. From the control engineering point of view, the proposed method designs a controller that stabilizes the robot to an equilibrium trajectory.

In this paper, we develop a 3-degree of freedom (DOF) mechanism for humanoid robots, which we call the cybernetic shoulder. This mechanism imitates the motion of the human shoulder and does not have a fixed center of rotation, which enables unique human-like motion in contrast to the conventional design of anthropomorphic 7-DOF manipulators that have base three joint axes intersecting at a fixed point. Taking advantage of the cybernetic shoulder's closed kinematic chain, we can easily introduce the passive compliance adopting the elastic members. This is important for the integrated safety of humanoid robots that are inherently required to physically interact with the human.

In this paper, we design a continuous symbol space using a dynamics-based information processing system. One point in the symbol space decides the vector field in the motion space that generates the cyclic motion and the continuous motion transition of the robots. Because the motion of the state vector in the symbol space is defined by a dynamical system, the spatial and temporal continuous information processing system is realized.

In this paper, we develop two mechanisms for improving humanoid robot motions. The double spherical joint is a six DOF mechanism whose axes intersect in one point. This mechanism is used for humanoid hip joints with a waist joint function without increasing the actuator. The backlash clutch realizes a high torque driving and a free joint using backlash mechanisms is used for knee joints. The free mode will play a role in humanoid behavior that is dynamically coupled with the environment. The humanoid robot with these two mechanisms is developed and results of preliminary experiments are shown.

In this paper, we develop the on-line design method and the hierarchical design method of dynamics based information processing system for the robot intelligence. By using the forgetting parameter, dynamics memorizes a new robot motion forgetting an old motion, which means the plasticity of the system. The hierarchical structure enables information processing for complex and continuous environment. We implement the proposed method to a humanoid robot and realize the motion generation and transition.

Use of compliance in muscle is the inherent skill of a human. By using the potential energy charged in the compliant members, we can skillfully equalize the characteristics of muscles and body. Integrating the skill of compliance will provide robots with higher mobility, dexterity and safety and extends the fields of applications. The main research issues of the skill of compliance are tuning passive compliance, planning compliant motion and designing control law. To achieve the skill, we focus on the planning compliant motion considering the kinetic energy. In this paper, we propose to design a compliant motion through iterative model identification and motion design. A humanoid robot with passive compliance is used to integrate the skill of compliance and shows fast swing charging and discharging the kinetic energy.

For the development of an intelligent robot with many degrees-of-freedom, the reduction of the whole body motion and the implementation of the brain-like information system is necessary. We propose a reduction method of the whole body motion based on singular value decomposition and a design method of the brain-like information processing system using a nonlinear dynamics network with polynomial configuration. By using the proposed method, we design the humanoid whole body motion that is caused by the input sensor signals.

Design of mechanical compliance would be one of the most important technical foci in making humanoid robots really interactive with the humans. For safety insurance mechanical compliance should be developed for humanoid robots. The introduction of the passive compliance to humanoid robots has large possibility for achieving human skill by using the dynamical energy stored in the compliant members. Programmable passive compliance plays an important role in coping with the changing environments and task execution. We evaluate the effectiveness of the passive compliance for the realization of human skill and design a programmable passive compliance mechanism 'PPC cybernetic shoulder' which is a four degree of freedom shoulder mechanism for humanoid robots using a closed kinematic chain. The programmability of the PPC cybernetic shoulder is evaluated by experiments.

Design and control of mechanical compliance would be one of the most important technical foci in making humanoid robots really interactive with humans. For task execution and safety insurance the issue must be discussed and offers useful and realistic solutions. We propose a theoretical design principle of mechanical compliance. Passive compliance implies a mechanically embedded compliance in drive systems and is reliable but not tunable in nature, while active compliance is a controlled compliance and, therefore, widely tunable, but less reliable specially in the high frequency domain. The basic idea of the paper is to use active compliance in the lower frequency domain and to rely on passive compliance in the higher frequency. H/sub /spl infin// control theory based on systems identification allows a systematic method to design the hybrid compliance in frequency domain. The proposed design is applied to the shoulder mechanism of a humanoid torso robot. Its implementation and experiments are to be shown with successful results.

Discusses the integration of "mechanical softness" into the humanoid robot mechanisms design. The mechanical softness includes such requirements as human-like high mobility and human-like sensitive compliance. We focus on the shoulder mechanism, and propose a parallel mechanism to integrate the two requirements. The mechanism is called the cybernetic shoulder and possesses three degrees-of-freedom. The nature of motion curves of the human shoulder, and the design and development of the cybernetic shoulder are described with the computation issue of kinematics. The integration of compliance into the parallel mechanism is also discussed, and its experimental evaluation is made.

We propose a control scheme of parallel manipulators focusing on the accuracy of acceleration on the endplate, which is an important factor when parallel manipulators are used as acceleration displays. We use two controllers-a dynamic controller to achieve accuracy of position and to stabilize the system, and an H/sub /spl infin// controller to feedback the acceleration measured on the endplate. The main problem of dynamic control is computational complexity. In order to reduce computation time for inverse dynamics, a parallel processing method called multi-thread programming is applied. The H/sub /spl infin// controller is added outside the closed loop of the dynamic control to remove the vibration of the structure and the influence of modeling errors in the dynamic controller.