Robust control for a class of uncertain nonlinear systems with input quantization

In this paper, we propose a robust tracking control scheme for a class of uncertain strict-feedback nonlinear systems. In these systems, the control signal is quantized by a class of sector-bounded quantizers including the well-known hysteresis quantizer and logarithmic quantizer. Compared with the existing results in input-quantized control, the proposed scheme can control systems with non-global Lipschitz nonlinearities and unmatched uncertainties caused by model uncertainties and external disturbances. It is shown that the designed robust controller ensures global boundedness of all the signals in the closed-loop system and enables the tracking error to converge toward a residual, which can be made arbitrarily small.