Velocity observer design for a class of uncertain nonlinear mechanical systems: a self-adaptive fuzzy logic-based approach

This study focused on designing a smooth velocity observer (VO) for mechanical systems whose mathematical model is uncertain. The uncertainties that appear in the observer dynamics are, via utilising their universal approximation property, modelled with fuzzy logics. A novel self-adaptive fuzzy logic (SAFL)-based term in which control representative value matrix (CRVM), centres and widths of membership function are all dynamically updated is used as part of the observer design. Through the application of Lyapunov-type stability analysis techniques, the practical stability of the observed velocity error was guaranteed. The outcomes derived from experimentation on a planar robotic manipulator are showcased to illustrate the performance of the devised VO design.