Adaptive event-triggered robust front wheel steering angle control strategy for a novel electro-hydraulic composite steer-by-wire

Abstract

The steer-by-wire (SBW) system is an important foundation for the realisation of self-driving trucks. However, the traditional SBW cannot meet the steering performance requirements of self-driving trucks due to power limitation. Therefore, this paper proposes a novel electro-hydraulic composite steer-by-wire (EH-SBW) system. The linear time-varying model and energy-saving characteristics of the new steering system are analysed. In order to improve the angle tracking accuracy and reduce the energy consumption of the novel steering system, an adaptive event-triggered robust front wheel steering angle control strategy is proposed in this paper. This strategy consists of two parts: the interval type-2 (IT2) fuzzy observer and the event triggered tube model predictive control (ET-TMPC). Fuzzy rules and primary membership functions based on the air dissolution characteristics in the hydraulic cylinder are designed. IT2 fuzzy observer estimates the nominal bulk modulus and bulk modulus perturbation bounds of the hydraulic fluid based on the fuzzy rules. ET-TMPC calculates the control volume and execution step size based on the event triggering mechanism and IT2 fuzzy observer to improve the angle tracking accuracy and reduce the computational cost. The EH-SBW test bench is built to verify the feasibility of the proposed strategy. The experiments show that compared with the existing control strategies, the proposed method not only improves the angle tracking accuracy and energy consumption performance of the EH-SBW, but also saves the computational resources of the controller.