Nonlinear Observer Design with Time-varying Bandwidth for Robot Manipulators

In this paper, a novel states and disturbances observer is designed to simultaneously observe both lumped uncertainties/disturbances and unmeasurable joint velocities of robot manipulators. The proposed observer inherits the advantages of the previous nonlinear observer with high estimation accuracy and a simple structure compared to other observers. However, to increase the steady-state estimation accuracy without deteriorating the transient response, a time-varying bandwidth mechanism is proposed which adjusts the observer bandwidth according to the output estimation error. The stability of the proposed observer is proved based on Lyapunov theory. Simulation results validate the performance of the proposed method.