A lyapunov function-based procedure to design output feedback tracking controllers for Euler-Lagrange systems

A procedure to design output feedback tracking controllers for Euler-Lagrange systems is proposed. This procedure is based on the natural energy Lyapunov function, unifying the stability analysis for designs of control laws in the situations of either unconstrained or constrained torque input. Since only generalized positions are measured, dynamic filtering is used to obtain an estimation of the velocity tracking error. In the stability analysis we show the global exponential convergence result for the position and velocity tracking errors, and the local exponential convergence result for the output of the dynamic filtering.