Dynamic Control of Flexible Joint Robots with Constrained End-Effector Motion

Abstract

In this paper, a nonlinear feedback control based on inverse dynamics is proposed for robots with flexible joints during constrained motion task execution. The joint flexibility is included in the controller design since it can cause the instability of robot force control. Based on constrained system formalism, the presented control scheme achieves simultaneous, independent control of both position and contact force at the robot end-effector. The method can be directly applied to robot control, or it can be used as the basis for developing other advanced control strategies. In this paper, an adaptive control algorithm is proposed. Control inputs are composed of feedforward and feedback terms. The feedforward component consists of nominal torques calculated from inverse dynamics, which allows the system to be linearized about the desired trajectory. The feedback component corresponds to perturbation torques computed from the adaptive self-tuning control algorithm. The results of numerical simulation do confirm the effectiveness of the method.