Basis-motion torque composition approach: generation of feedforward inputs for control of multi-joint robots

This paper focuses on generation of feedforward torque for precise joint-trajectory tracking of a multi-joint robot arm with serially connected links. A proposed method called basis-motion torque composition, based on four arithmetical operations of time-series torque data for several motions, allows to generate feedforward torque for a motion whose final posture and time profile are specified. The torque-generation algorithm is presented, and the experimental results by a two-joint robot arm are illustrated. The experimental results demonstrate that the tracking errors of angular velocities by the basis-motion torque composition tend to be smaller than those by the computed torque method.