Input-to-State Stable Hybrid Momentum Observer for Mechanical Systems

This letter examines the dynamic properties of a hybrid momentum observer for mechanical systems, extending the previously-reported results. The observer estimates the momentum vector from measurements of the configuration vector and is shown to be input-to-state stable with respect to external perturbations. In the absence of external perturbation the observer is shown to be globally exponentially stable, converging at a user-controlled rate. The observer is constructed from a port-Hamiltonian representation of mechanical systems and exhibits a passivity property with respect to an input-output port that can be utilised for subsequent control design. The theoretical results are demonstrated via numerical simulation on a 2-link vertical manipulator.