Yoshikazu Kanamiya

Ankle and hip balance control strategies with transitions

A method for implementing the ankle and hip balance control strategies, well known from studies on human balance control, is suggested. The moment of the acting disturbance force is evaluated continuously in real time via the difference between the ZMP and the ground projection of the center of mass. Compliant response to the continuous disturbance is ensured by attaching a virtual spring-damper in an appropriate way for each strategy. Further on, whenever the limit of the ankle strategy is reached, a smooth transition toward the hip strategy is initialized and compliance is ensured in a continuous way and in agreement with the disturbance. After the disturbance is removed, the humanoid switches first back to the ankle strategy, and then returns to the initial equilibrium (erect) posture. Experimental data taken with a small humanoid robot (HOAP-2) are presented to validate the method. See also the accompanying video clip.

Reactionless resolved acceleration control with vibration suppression capability for JEMRMS/SFA

We propose an integrated motion controller for the Japanese Experimental Module RMS/SFA “macro-mini” manipulator system on the International Space Station. This controller is based on the Reaction Null-Space concept described in previous works. The performance of this controller with a planar flexible-base manipulator has been studied in [1]. Here, we show how to implement the controller for the JEMRMS/SFA system and examine its performance via simulations. Results show that end-effector path tracking combined with reactionless motion and vibration suppression can be achieved in a stable way, by making use of the inherent kinematic/dynamic redundancies of the system.

Singularity-Consistent Torque Control of a Redundant Flexible-Base Manipulator

A path tracking controlmethod for a kinematically redundant manipulator on a flexible base is proposed. The method is based on dynamic redundancy resolution through a vibration suppression constraint. It is shown that the end-effector path can pass via an algorithmic singularity without destabilizing the system. Simulation data from a planar system is presented, confirming that stable path tracking can be achieved within large portions of the manipulator workspace.

Inertia-coupling based balance control of a humanoid robot on unstable ground

A humanoid robot should be able to keep balance in the presence of various disturbances. We address here a class of disturbances that are due to an unstable ground, when conventional methods of control, e.g. ZMP based ones, are not applicable. The equation of motion has the form of an underactuated system, such as that of a free-flying robot or of a flexible-base/flexible-link robot. We develop an inertia-coupling based control method, similar to the control methods used in previous works for vibration suppression of flexible-base robots. Simulations with a planar humanoid robot are presented for two types of disturbances: (i) rotating surface and (ii) jointed-toe foot model. It is shown that, under the proposed control laws, balance can be recovered in a stable and optimal way, in both cases.

Pseudoinverse-Based Motion Control of a Redundant Manipulator on a Flexible Base with Vibration Suppression

We propose a method for motion control of a redundant manipulator on a flexible base. Manipulator selfmotion is determined from a velocity-level additional constraint obtained from base vibration dynamics. End-effector path tracking is ensured via pseudoinverse-based velocity control. In this way, algorithmic singularities associated with the additional constraint are avoided. The vibration suppression control component is derived via the SingularityConsistent method, which aleviates destabilization during vibration suppression in the vicinity of kinematic singularities. Experimental data from a 3R planar manipulator on a flexible base confirmed the feasibility of the proposed method.

Towards an open-source integrated development and real-time control platform for robots

The paper proposes an open-source platform for developing kinematic and dynamic models, simulation and control design of robots, based on MaTX [1]. We show that the developed programs can be easily transfered for direct execution in real-time, making use of improvements in the recent Linux kernel toward hard real-time capability. We show that, in combination with the real-time preemption patch of Ingo Molnar [2], there is the potential for real-time control of a robot arm. This is confirmed through experiments for real-time control of a Mitsubishi Heavy Industries seven-DOF PA-10 robot [3].

Walking control around singularity using a Spherical Inverted Pendulum with an Underfloor Pivot

Humans utilize the configuration with extended knees to achieve efficient walk. A humanoid robot, however, cannot do so, since this posture is a singular configuration. In order to tackle this problem, in our previous work, a walking pattern generator based on the spherical inverted pendulum model has been proposed. It enables to generate up-and-down waist motions and utilizes the singularity neighborhood in the middle of each support phase. However, the spherical inverted pendulum model cannot move the ZMP during each single support phase. In this paper, we propose a new approach to generate a walking pattern based on a Spherical Inverted Pendulum model with an Underfloor Pivot (the SIPUP method). With this method, the ZMP gains mobility during each singleleg support phase, and walking with a smaller acceleration is achieved. In addition, it becomes easy to utilize the singularity neighborhood. As a result, the knee joint can be almost fully extended (to less than 0.01 rad). Experimental results show the effectiveness of our approach.

Natural self motion of a robotic limb with single degree-of-redundancy

The self motion of a kinematically redundant robotic limb with single degree of redundancy is analyzed, focusing thereby on the nonlinear self-motion component. The role of this component has been completely ignored in past studies on self motion. It is shown that Jacobian pseudoinverse-based resolution - the usual resolution method for nonlinear self-motion - yields poor dynamic performance. A special type of self motion is identified based on the natural metric on the self-motion manifold and the energy conservation principle. This type of self motion is shown to have superior dynamics in terms of torque requirement and to avoid abrupt fluctuations in acceleration in the vicinity of singular points.

Assessment of Reaction-Null Space Based Motion Control During Practical Camera Inspection Task

This work describes an inspection task using a hand-held camera to be performed with a realistic freeflying space manipulator, without imposing reaction moments on the satellite base. To ensure a wide workspace under this condition, special care is taken about the algorithmic singularities encountered. These are shown to be successfully handled via the Singularity-Consistent method. The performance is verified through numerical simulation for a number of manipulator configurations and desired wrist motions. It is confirmed that the inspection task is suitable for a tele-operated space robot system, even in the presence of algorithmic singularities. In addition, it is shown that an inspection task under reactionless motion control has an advantage from the perspective of energy efficiency, when compared to reaction compensation via the reaction wheels.

State Recognition of House Chores by Environmental Sound Source Estimation Utilizing Location Information of Home Robot

By performing sound source estimation using location information of home robot and a result of sound source localization by HARK, the robot can recognize environmental sounds based on the sound source. Thus, it is possible to distinguish even if similar sounds of feature quantities are generated, so that precision of state recognition of house chores is increased. In this paper, we developed the state recognition system and performed experiments of operation works of a microwave oven. As a result, the localization results were facing a direction of the microwave oven, and so it can be said that it is possible to recognize the sound source accurately.