A Class of OFT Controllers for Torque-Saturated Robot Manipulators: Lyapunov Stability and Experimental Evaluation

The trajectory tracking of robot manipulators is addressed in this paper. Two important practical situations are considered: the fact that robot actuators have limited power, and that only position measurements are carried out. Let us notice that a few solutions for the torque-bounded OFT (output feedback tracking) control has been proposed. In this paper we contribute to this subject by presenting a class of OFT controllers for torque-constrained robots. The theory of singularly perturbed systems is crucial in the analysis of the closed-loop system trajectories. As a second contribution of this paper, we present a detailed experimental study of six control schemes, which were tested in a two degrees-of-freedom direct-drive robot, confirming the advantages of the proposed methodology.