Trajectory Tracking Control of Robot Manipulators with Revolute Joints using Only Position Measurements

This paper deals with the problem of output feedback tracking control of revolute joined robot manipulators with unmeasurable velocities. The controller consists of three parts: (1) a feedforward term, (2) a first-order linear dynamic compensator, and (3) a nonlinear proportional-like term. Due to the presence of angular variables, the closed-loop system is shown to have a set of all equilibrium points that corresponds to the zero position in a cylindrical phase space. We provide the result on a semi-global asymptotic stability of a reference trajectory. The usefulness of our controller is demonstrated in a simulation study of a three-link spatial robot manipulator.