Quantized controller for a class of uncertain nonlinear systems with dead-zone nonlinearity.

In this paper, a quantized controller is designed for a class of uncertain nonlinear systems subjected to unknown disturbances and unknown dead-zone nonlinearity. A general class of strict feedback nonlinear systems is taken as the plant to design the controller. Here, each differential equation of the system is considered to have unknown parameters and time-varying disturbances. The maximum upper bound of the disturbances is estimated instead of estimating each disturbance. This novel idea reduces the computational cost in handling the disturbances in uncertain systems. The tuning functions are constructed to estimate the unknown system parameter and maximum upper bound of the disturbances. It is considered that the actuator dead-zone nonlinearity is bounded by an unknown parameter and incorporated to design the final quantized controller. A backstepping technique is applied to design the tuning functions and controller that stabilizes the uncertain system. The stability of the proposed controller is proved using the Lyapunov stability based theory. The obtained MATLAB simulation test results verify the designed proposed controller.