Robot angular link velocity estimation in the presence of high-level mixed uncertainties

The estimation problem of the angular link velocity via a nonlinear high-gain observer is considered. It is solved in the presence of essential parametric uncertainty and external noise perturbations based only on current position measurements. The obtained state space estimation error turns out to be robust with respect to given uncertainties, and its bound can be expressed by a linear combination of the internal (parametric) and external (noise type) uncertainty levels. The simulation results, concerning a robot manipulator with two degrees of mobility and with unknown friction parameter subjected to variations within a given interval, illustrate the effectiveness of the suggested technique.