Sliding mode control of quantized systems against bounded disturbances

This paper investigates the sliding mode control problem of quantized systems with simultaneous input and output disturbances. In a network environment, the output measurements are supposed to be quantized with a logarithmic strategy before transmitting over the digital channels. The main difficulties in this design are as follows: (1) there exists input/output disturbances and state time-delay in the plant under consideration, such that model discretization is difficult to be implemented. The design work is therefore forbidden to be considered in continuous-time domain; (2) the quantized signals (piecewise constants) cannot be used to synthesize a continuous-time sliding mode surface; (3) traditional observer technique is not effective to handle output disturbances. In this paper, a filtering-based technique is proposed to solve these difficulties, based on which a sliding-mode observer-based control scheme is developed to stabilize the resulting closed-loop systems. Finally, the effectiveness of the proposed methodology is illustrated via a numerical example.