A DESIGN METHODOLOGY FOR ZERO REACTION ROBOTS

Abstract

In many applications of advanced robotic systems, reaction forces and moments transmitted by a manipulator to its base are highly undesirable. Such reactions reduce the accuracy of high-speed manipulators, destroy zero-g environments in space, require the use of thruster fuel to stabilize free-flying space robots, or excite suspension modes in mobile robotic systems. In this paper, we analyze the problem of force and torque transmission in robotic systems, and propose design and planning methods that can reduce it, or eliminate it. It is shown that designing a force-balanced manipulator with an invariant mass matrix, and employing appropriate trajectory planning, can result in reactionless motions. Two redundant planar manipulator designs, that can be used as building blocks of more complicated systems, demonstrate the usefulness of the proposed methods. An important advantage of these methods is that if reactionless behavior is not needed, system redundancy can be recovered.