基于齿条力估计的线控转向系统主动跟踪器研究

Active tracking controller of steer-by-wire system by rack force estimation

针对智能驾驶线控转向系统的精确转向跟随问题,对线控转向系统的动力学模型建立、外部干扰因素分析及估计补偿、转向跟随控制算法设计等进行了研究。提出了适用于线控转向系统的主动跟踪器,通过实时估计外部齿条力,并进行前馈补偿的方式改善了系统的跟随性能;利用一种基于扩张干扰观测器的齿条力估计方法,将估计结果与鲁棒滑模控制器相结合,设计出了适用于线控转向系统的主动前馈跟踪算法;基于ISO汽车转向系统相关测试标准,在不同工况下对算法进行了硬件在环实验验证。研究结果表明:齿条力估计算法能够实时有效地对外部齿条力进行估计,同时主动跟踪器提升了线控转向系统的转向跟随性能,并且其改善效果在高速大负载工况下更为显著。

Aiming at the precise tracking control of steer-by-wire(SBW) system in intelligent vehicles, dynamic modelling of SBW system, external disturbance analysis and estimated compensation and tracking motion controller design were researched. An active tracking controller specified for SBW system was proposed, and a rack force estimator based on an extended disturbance observer was utilized for estimation and compensation, and finally combined with a robust sliding mode controller to obtain the whole design of the active tracking controller of the SBW system. Meanwhile, based on ISO standards for vehicle steering performance test, experiments with different road conditions were done to validate the proposed algorithms. The results indicate that the rack force can be estimated online effectively, and the tracking performance of the steer-by-wire system equipped by the active tracking controller is improved a lot, and the effects stand out especially in large velocity and large load working condition.