Sliding Mode Observer-Based State Estimation Under Event-Triggered and Quantized Communication

This paper investigates the design of sliding-mode observer (SMO) for state estimation in networked control systems operating under event-triggered sampling and signal quantization constraints. To address the challenges posed by the inherent non-differentiability of quantized outputs at event-triggered instants, a novel two-stage SMO framework is proposed. In the first SMO, a sliding surface is constructed based on partial estimation errors, while in the second SMO, continuously differentiable output vectors reconstructed from quantized measurements are employed to define an alternative sliding surface. This dual observer structure ensures reliable sliding surface construction even in the presence of discontinuous signals. Moreover, to effectively alleviate transmission-induced errors arising from asynchronous sampling and finite-precision communication, the proposed SMO integrates both the event-triggering threshold and the quantization parameter into the design of the observer’s switching gain. This joint incorporation ensures the stability of the error dynamics even in the presence of communication imperfections. The effectiveness and robustness of the proposed method are further demonstrated through an illustrative example of a spacecraft relative motion model in Sun−Earth L₂ point.