Steering execution control of steer-by-wire system with backlash compensation and disturbances observation for autonomous vehicle

An important function of the steer-by-wire (SBW) system is to follow a desired steering angle accurately. However, it is impossible to avoid transmission backlash in the servo system, which will aggravate the mechanical vibration and cause delays and fluctuations in control system responses. A composite controller for permanent magnet synchronous motor (PMSM) servo system is proposed in this paper to solve the adverse effects resulting from backlash of the SBW system. To mitigate the effects of backlash nonlinearity, the dead-zone backlash model is identified utilizing the particle swarm optimization (PSO) algorithm, and its influence is compensated in the controller. Additionally, to address the model declination and unpredictable disturbances, a nonsingular fast terminal sliding mode controller (NFTSMC) combined with a super-twisting extended state observer (STESO) is designed. In simulation experiments, a SBW control system model is built to evaluate the performance of the disturbance observer and the angle following controller. In hardware-in-loop (HIL) experiments, the angle tracking control capability of the novel method is further evaluated under the double lane change condition. Finally, the results of simulation and HIL experiments are offered to validate the excellence of the novel method.