Adaptive control of a DC motor with uncertain deadzone nonlinearity at the input

This paper presents an adaptive control scheme for systems with uncertain deadzone nonlinearity at the input of a linear plant. A new model for deadzone inverse is developed and used in conjunction with any conventional controllers in order to reduce the effect of deadzone nonlinearity. The deadzone inverse model is notationally compact and is simpler to implement than existing schemes. Two cases are considered: The case where the deadzone spacing is known as well as the case of uncertain deadzone spacing. For the latter case, an adaptive update law is developed to estimate the deadzone spacing. The adaptive deadzone inverse controller is a breakaway from existing deadzone compensators which are implemented in discrete-time and can easily be combined with any of the advanced control methodologies. The stability of the closed-loop system is shown using Lyapunov arguments. Simulation results show that the control methodology greatly improves tracking performance over a PD type controller.