Position control of robot manipulators with elastic joints using force feedback

Abstract

Abstract Transmission flexibility, as a predominant source of mechanical resonance, often results in inaccurate tracking of prescribed robot trajectories. Thus, the control algorithm must compensate not only for nonlinear dynamics of the arm and payload variations, but also for resonant effects in joints. The compensation for all of these effects results in a very complicated control algorithms which are difficult to apply in practice. In this article we suggest the measurement of torque/force on the output shaft of elastic reducer in order to compensate for elastic effects. The torque measurement can be replaced by the simultaneous measurement of the joint and the motor‐shaft angle. Then, we introduce a dynamic compensator with two zeros and two poles to filtrate the torque signal. It appears that the obtained control law is very simple and compensates for nonlinear system dynamics, variable payload parameters and resonant effects in joints. The proposed control scheme is illustrated by computer simulation of a six‐degree‐of‐freedom robot.