基于滚动时域算法的汽车电动助力转向电流跟踪方法研究

Research on Current Tracking Method of Electric Power Steering Based on Receding Time Domain Algorithm

电动助力转向系统在路面干扰、传感器噪声的影响下会造成驾驶员不良路感,同时,转向系统里的不确定性也会造成控制困难。针对EPS系统在控制过程中,无法在保证性能的同时解决系统的干扰和噪声以及不确定性问题,提出了基于滚动时域算法的EPS电流跟踪方法,该方法通过反复实时采集车辆的状态计算最优控制率,将电流的跟踪性能作为主要的控制目标之一,通过检测到的实际输出对基于模型的预测结果反复修正,最终计算得到合适的助力矩使系统能最大程度地兼顾鲁棒性与性能。首先通过建立EPS的系统模型,同时引入汽车二自由度汽车模型、轮胎模型,构建系统的状态空间方程。然后,以较好的电流跟踪性能、较好的抗干扰性能以及较好的操纵稳定性能为控制目标,在加入随机干扰信号的系统状态空间基础上,设计了滚动时域控制器,并对EPS系统进行仿真分析及硬件在环实验验证。结果表明:采用滚动时域控制方法可以更好地实现EPS目标电流跟踪,有效抑制外部干扰噪声的影响,提高系统的性能以及鲁棒性,保证驾驶员获得良好的路感,提高系统转向操纵稳定性能。

Under the influence of road surface interference and sensor noise,the electric power steering system will cause poor road sense for drivers.Meanwhile,the uncertainty in the steering system will also cause control difficulties.In the process of EPS system control,it is difficult to guarantee the performance as well as solve the problem of interference and noise of the system and model uncertainty at the same time.Thus,this paper puts forward the EPS current tracking method based on receding time domain algorithm.This method calculates the optimal control rate by repeatedly collecting the state of the vehicle in real time,takes the tracking performance of the current as one of the main control targets,and repeatedly corrects the prediction results based on the model through the actual output detected,and finally obtains the appropriate assisting torque to enable the system to maximize both robustness and performance.In this paper,firstly the system model of EPS is established,and the two-degree-of-freedom vehicle model and tire model are introduced to construct the state space equation of the system.Then,with better current tracking performance,better anti-interference performance and better maneuvering stability as the control target,a receding time-domain controller based on the system state space with random interference signals was designed,and the EPS system was simulated and verified by experiments in the loop.The results show that the receding time-domain control method can achieve EPS target current tracking better,effectively suppress the influence of external interference noise,improve the performance and robustness of the system,ensure the driver to get a good sense of the road,and improve the system steering stability performance.