Observer-based adaptive sliding mode control for steer-by-wire systems with event-triggered communication

This paper proposes an event-triggered adaptive sliding mode control for the steer-by-wire (SbW) system subject to unavailable state, time-varying disturbance, and limited communication resources. Firstly, an adaptive state observer is proposed to estimate the unmeasured state of the SbW system. The uncertain nonlinearity and the time-varying can be estimated by the adaptive fuzzy logic system and the disturbance observer, respectively. Then, considering the limited communication resources, an even-triggered adaptive sliding mode control is proposed for the SbW system. The key advantage is that the proposed control scheme can offset the observation error and the event-triggering error. Much importantly, the high-frequency switching function is nested in the control input without increasing the input–output relative degree of the controlled system, such that the chattering-free control input can be obtained. Finally, theoretical analysis shows that the practical finite-time stability of the closed-loop SbW system can be saved, and communication resources in the controller-to-actuator channel can be saved while avoiding the Zeno-behavior. Numerical simulations and experiments are given to evaluate the effectiveness of the proposed scheme.