A Statically Balanced Direct Drive Manipulator

A practical architecture, using a four-bar-linkage, is cgnsidered for the University of Minnesota direct drive robot [8]. This staticallybalanced direct drive robot has been constructed for stability analysis of the robot in constrained manipulation [5 -7]. As a result of the elimination of the gravity forces (without any counter weights), smaller actuators and consequently smaller amplifiers were chosen. The motors yield acceleration of 5g at the end point without overheating. High torque, low speed, brush-less AC synchronous motors are used to power the robot. Graphite-epoxy composite material is used for the construction of the robot links. A 4-node parallel processor has been used to control the robot. The dynamic tracking accuracy -with the feedforward torque method as a control lawhas been derived experimentally. Figure 1: University of Minnesota Direct Drive Ann