Enhanced optimal backlash compensation for transmission servo systems via a reduced-order GPI observer: a switched control design

This article presents a switched control approach for simultaneous backlash compensation and disturbance rejection in transmission servo systems (TSSs), which suffer from the degraded servo performance due to these challenges. Leveraging the switching dynamics inherent in TSSs with backlash nonlinearity, a composite switched control strategy is proposed. Specifically, a reduced-order generalized proportional integral observer (RGPIO) based antidisturbance control law is first designed as a baseline controller for “contact mode” subsystem to stabilize the closed-loop system and attenuate disturbances. Subsequently, an enhanced optimal control law, incorporating disturbance previews provided by RGPIO, is innovatively developed for the “backlash mode” subsystem to eliminate the hysteresis and oscillation induced by nonlinear backlash. Within this composite switched control framework, both asymptotic position convergence and optimal backlash transmission are achieved even under time-varying disturbances. Rigorous stability analysis of this switched system is established. Simulation and experimental results in the presence of both transmission backlash and external disturbances are provided to comprehensively validate the effectiveness of the proposed control approach.