Inverse dynamics position control of a compliant manipulator

The cycle time of typical industrial manipulators is limited by vibrational characteristics associated with drive train compliance. In this paper the effects of drive train compliance and actuator dynamics in a two-degree-of-freedom manipulator are modeled and a position controller based on inverse dynamics is developed. Simulation of various controllers is performed utilizing the Advanced Continuous Simulation Language. It is shown that the closed loop frequency response of the manipulator can be increased beyond typical industrial practices by considering the drive train compliance in the design and providing suitable feedback measurements. Simulations suggest that satisfactory performance can be obtained as high as the limit imposed by the manipulators unmodeled higher vibration modes. The controller based on inverse dynamics is shown to effectively decouple the manipulator's nonlinearly coupled degrees of freedom and perform better than a linear independent joint controller which also considers drive train compliance.