Design and analysis of a statically balanced direct-drive manipulator

Abstract

A statically balanced direct-drove robot has been constructed for stability analysis of the robot in constrained maneuvers. Using a four-bar linkage, a practical architecture is presented for the University of Minnesota direct-drive robot. As a result of the elimination of the gravity forces (without any counterweights), smaller actuators and amplifiers were chosen. The motors yield an acceleration five times that of gravity at the robot end point without overheating. High-torque low-speed brushless AC synchronous motors are used to power the robot. A graphite-epoxy composite is used to construct the robot links. A four-node parallel processor has been used to control the robot. The dynamic tracking accuracy, with the feedforward torque method as a control law, has been derived experimentally. The compliance and its stability condition have been analyzed and demonstrated experimentally.