In this paper, we describe a new scheme for redundancy control of robot manipulators. We introduce the concept of task priority in relation to the inverse kinematic problem of redundant robot manipulators. A required task is divided into subtasks according to the order of priority. We propose to determine the joint motions of robot manipulators so that subtasks with lower priority can be performed utilizing re dundancy on subtasks with higher priority. This procedure is formulated using the pseudoinverses of Jacobian matrices. Most problems of redundancy utilization can be formulated in the framework of tasks with the order of priority. The results of numerical simulations and experiments show the effectiveness of the proposed redundancy control scheme.

Task-priority based redundancy control of robot manipulators

This article presents a survey of the existing computational algorithms meant for achieving four important properties in autonomous multifingered robotic hands. The four properties are: dexterity, equilibrium, stability, and dynamic behavior The multifingered robotic hands must be controlled so as to possess these properties and hence be able to autonomously perform complex tasks in a way similar to human hands.Existing algorithms to achieve dexterity primarily involve solving an unconstrained linear programming problem where an objective function can be chosen to represent one or more of the currently known dexterity measures. Algorithms to achieve equilibrium also constitute solving a linear program ming problem wherein the positivity, friction, and joint torque constraints of all fingers are accounted for while optimizing the internal grasping forces. Stability algorithms aim at achiev ing positive definite grasp impedance matrices by solving for the required fingertip impedances. This problem reduces ...

Robot grasp synthesis algorithms: a survey

Practical application of the task-priority redundancy resolution technique must deal with the occurrence of kinematic and algorithmic singularities. The aim of this paper is twofold. First, the application of existing singularity-robust methods to the case of kinematically redundant arms is studied. Then, a new task-priority redundancy resolution technique is developed that overcomes the effects of algorithmic singularities. Computational aspects of the solutions are also considered in view of real-time implementation of a kinematic control algorithm. The method is applied to a seven-degree-of-freedom manipulator in numerical case studies to demonstrate its effectiveness.

Singularity-robust task-priority redundancy resolution for real-time kinematic control of robot manipulators

The exploitation of kinematic redundancies in robotic systems may provide more dexterity and versatility in the execution of complex tasks. When functional constraint tasks are imposed in addition to the end-effector tasks, a task priority strategy is advisable. The authors propose a general framework for managing multiple tasks in highly redundant systems. In particular, they derive joint velocity and acceleration solutions which can be used as reference input trajectories to suitable model-based controllers. They also develop a recursive implementation, and discuss the occurrence of singularities in the Jacobian associated with the generic task. Two case studies illustrate the effectiveness of the algorithm on a snake-like robot. >

A general framework for managing multiple tasks in highly redundant robotic systems

In this paper, we present a tentatively comprehensive tutorial report of the most recent literature on kinematic control of redundant robot manipulators. Our goal is to lend some perspective to the most widely adopted on-line instantaneous control solutions, namely those based on the simple manipulator's Jacobian, those based on the local optimization of objective functions in the null space of the Jacobian, those based on the task space augmentation by additional constraint tasks (with task priority), and those based on the construction of inverse kinematic functions.

Kinematic control of redundant robot manipulators: A tutorial

Inverse kinematic solutions with singularity robustness for robot manipulator control

This paper discusses the optimal redundancy control problem of robot manipulators. The redundancy control problem has mostly been discussed in the framework of instantaneously optimal control. In t...

Optimal redundancy control of robot manipulators

A power-assisting device is being developed to help older persons and people with disabilities move themselves from beds to wheelchairs. The device is intended to contribute to a more independent life for these people and to greater utilization of their latent abilities. Self-support assistance, i.e., the support provided by a power-assisting device to the person without the need for aid from a caregiver, and capability of the device to assist the movements of the people are discussed. A method for the production of power assistance and motion guidance is then proposed for the device. Finally, a test of the performance of the developed system is described.

Assistance of self-transfer of patients using a power-assisting device

We developed a robotic orthosis capable of helping human forearm motion. This orthosis was carefully designed such that mechanical safety for human beings could be ensured. A power assist control scheme for the robotic orthosis is proposed. The performance of the developed system is examined by several experiments.

Development of an 8 DOF robotic orthosis for assisting human upper limb motion

A control scheme for pneumatic drive systems is proposed. In general, static friction, Coulomb friction, and other nonlinear disturbances crucially worsen the performance of pneumatic drive systems. In the proposed control scheme, to guarantee robustness against such disturbances and stability of the motion, position feedback loops and pressure feedback loops are hierarchically connected. The stability of the motion is investigated by using a Lyapunov function. As a result, it is mathematically proven that the motion of pneumatic drive systems converges to a fixed desired point as time tends to infinity, even if the disturbances affect the motion. The effectiveness of this control scheme is demonstrated through some experimental results. >

Hideo Hanafusa

Papers

Inverse kinematic solutions with singularity robustness for robot manipulator control

Optimal redundancy control of robot manipulators

Assistance of self-transfer of patients using a power-assisting device

Development of an 8 DOF robotic orthosis for assisting human upper limb motion

PI type hierarchical feedback control scheme for pneumatic robots