Abstract
We consider the problem of designing robust tracking controllers for uncertain robotic manipulators where the actuators are coupled to the links via flexible joints. We impose no restrictions on the stiffness of the joints; hence robots with very flexible joints can be successfully treated with the proposed controllers. Each proposed controller guarantees exponential convergence of the tracking error for a compact set of initial states: for every compact set C of initial states, there is a controller from a family of nonlinear tracking controllers which guarantees that, provided the initial state is in C, the trajectory of the closed loop system converges exponentially to a small neighborhood of the desired trajectory. Controller design is based on singular perturbation theory and Lyapunov functions.
