Motion control of a robot arm using joint torque sensors

Abstract

A motion-control algorithm of a robot arm using a joint torque sensor is proposed. The algorithm contains the joint torque feedback from sensors mounted at joints and another feedback component that contains a nonlinear part that can be calculated easily. The feedback from the sensors is used to compensate not only the nonlinear dynamics of the arm but also the parameter variations and uncertainties of the arm. As the resultant control law does not depend on the mass properties of links, it is not affected by parameter variations and uncertainties caused by load. Several experiments illustrate effectiveness of the proposed control law, showing that the algorithm is more robust against parameter variations caused by a heavy load than the control law based on the computed torque method. The calculation of inverse dynamics in nonlinear feedback control laws can be replaced by a linearization with joint torque feedback proposed in this paper. In this sense, the method can be extended to other control algorithms involving the calculation of the inverse dynamics of an arm.