Experimental Evaluation of Nonlinear Feedback and Feedforward Control Schemes for Manipulators

The manipulator trajectory tracking control problem revolves around computing the torques to be applied to achieve accurate tracking. While this problem has been extensively studied in simulations, the real-time results have been lacking in the robotics literature. In this paper, we present the experimental results of the real-time performance of model-based control algorithms. We compare the computed-torque control scheme with the feedforward dynamics compensation scheme. The feedforward scheme compensates for the manipulator dynamics in the feedforward path while the computed-torque scheme uses the dynamics in the feedback loop for linearization and decoupling. The manipulator control schemes have been implemented on the CMU DD Arm 11 with a sampling period of 2 ms.