Delay-tolerant design of the steer-by-wire system in intelligent vehicles for closed-loop stability and maximal target-tracking performances of path-following

The automation of transportation systems inevitably faces challenges in enhancing passenger vehicle safety. In the transitional phase toward full automation, X-by-wire (XBW) technology plays a crucial role in bridging the gap, with steer-by-wire (SBW) systems serving as a key enabler of both automation and electrification. This paper addresses the issue of time delays in the lower control loop of SBW systems and proposes a delay-tolerant control design to ensure optimal target-tracking performance under varying delay conditions and tyre aligning moments. To achieve this, SBW system and control models are established, and a systematic approach for designing a stable SBW controller under time delay is developed. Furthermore, an optimisation strategy is formulated to maximise target-tracking performance, leading to a gain-scheduling control scheme. Simulation experiments are conducted to validate the effectiveness of the proposed design. The findings provide theoretical insights into system stability under delay and offer practical guidance for the onboard implementation of SBW systems.