Adaptive robust control for servo system with friction and input dead-zone nonlinearity

An adaptive robust control (ARC) algorithm is developed for servo system driving by gears with friction and dead-zone nonlinearity, parametric uncertainties and uncertain nonlinearities disturbances. The existing robust adaptive control methods mainly focus on using on-line parameter adaptation for friction and the approximate inversion of the unknown dead-zone. But even without other uncertain nonlinearities and disturbance, asymptotic output tracking can never be achieved by continuous controller for the non-smooth characteristics of friction and dead-zone. In this paper, the dead-zone inverse is not constructed. Furthermore viscous friction and elasticity force are considered in the system model. The proposed adaptive robust control law consists three parts: model compensation term, the robust control term and robust feedback term. The ARC ensures that all closed-loop signals are bounded and achieves the tracking within the desired precision. Simulations results illustrate the performance of the ARC.