Modular Relative Jacobian for Dual-Arms and the Wrench Transformation Matrix

A modular relative Jacobian is recently derived and is expressed in terms of the individual Jacobians of stand-alone manipulators. It includes a wrench transformation matrix, which was not shown in earlier expressions. This paper is an experimental extension of that recent work, which showed that at higher angular end-effector velocities the contribution of the wrench transformation matrix cannot be ignored. In this work, we investigate the dual-arm force control performance, without necessarily driving the end-effectors at higher angular velocities. We compare experimental results for two cases: modular relative Jacobian with and without the wrench transformation matrix. The experimental setup is a dual-arm system consisting of two KUKA LWR robots. Two experimental tasks are used: relative end-effector motion and coordinated independent tasks, where a force controller is implemented in both tasks. Furthermore, we show in an experimental design that the use of a relative Jacobian affords less accurate task specifications for a highly complicated task requirement for both end-effectors of the dual-arm. Experimental results on the force control performance are compared and analyzed

Modular Relative Jacobian for Combined 3-Arm Parallel Manipulators

This work presents a new formulation of a modular relative Jacobian used to control combined manipulators as a single manipulator with a single effector. In particular, this modular relative Jacobian is designed for 3-arm parallel manipulators. It is called a relative Jacobian because it is expressed relative to the reference frames at the manipulator end-effectors. It is modular because it uses the existing information of each standalone manipulator component to arrive at the necessary expressions for the combined system. This work is part of a series of studies to express a single end-effector control of combined manipulators, in parallel as well as other types of base configurations. This holistic approach of controlling combined manipulators affords a drastic increase of the null-space dimension and the convenience to use all the principles of controlling a single manipulator for the resulting combined system. Derivation of the modular relative Jacobian for a 3-arm parallel manipulator is shown, together will simulation results