Passivity-based elastic joint robot control with on-line gravity compensation

In this paper, a passivity-based controller with the link side on-line gravity compensation for elastic joints of robot manipulators is presented. In this study, a joint level position, torque control law with double loop construction: an outer the motor side position control, and an inner torque feedback are considered. In terms of torque feedback, a physical interpretation is addressed and analyzed for the purpose controller via passivity theory. It is proved by a Lyapunov function that the control law is globally asymptotically stabilizes at any reference configuration. Moreover, the control performance of algorithm is assessed by a simulation; the simulation study reveals a better performance regarding as the torque ripple in contrast to a proportional-derivative (PD) control.