Dynamic control strategy of dual-arm robot for asymmetric bimanual tasks: a human-inspired approach

Abstract

The highlight of this work is the holistic dual-arm control strategy for asymmetric bimanual tasks (ABTs). This is inspired by a study on roles of human bimanual action---Guiard’s three principles.

Firstly, we present a new concept, called relative impedance control, to create a control of two manipulators in a dual-arm system as an equivalent single manipulator under impedance control. This begins with an insight from an analogy between the Guiard’s first and third principles and a relative Jacobian. It results in a simple and convenient task specifications referenced at the end-effector of the equivalent single manipulator. An asymmetric bimanual task of a dual-arm system in real-time control is used to show the efficacy of the proposed controller, where the one arm (tool robot) writes a word on a board manipulated by the other arm (reference robot). Integrating concepts of time-delay estimation and ideal velocity feedback contributes to the ease of implementation for a dual-arm system.

Secondly, we propose a new formulation of a task-prioritized control strategy to conduct multiple, conflicting tasks. Critical to the proposed method is the use of relative Jacobian that creates ample degrees-of-redundancy to the dual-arm system. We formulate an acceleration-level redundancy resolution by using the task-prioritization scheme, and present a new control law that combines the task-prioritization and relative impedance control. The physical implementation uses a tool robot that draws a circle on the board attached to the reference robot, such that intentional conflict among subtasks is induced. The experimental results show that when such conflict occurs, the higher priority task is guaranteed an accurate execution without influence from the lower priority task.

Thirdly, we propose a human-inspired cost function to endow dual-arm system performing an ABT with useful self-motion. This is based on the Guiard’s second principle which addresses the different cap...