高速工况智能车辆转向系统混杂控制研究

Study on hybrid control based steering system for intelligent vehicle in high-speed condition

通过分析高速工况下交通事故的主要类型及驾驶员的3种基本驾驶行为,可知该工况下转向系统既有离散状态又有连续状态的特性,进而提出基于混杂系统理论的智能车辆转向系统多模式切换控制策略,并利用跨道时间和安全距离作为切换规律.以线控转向系统为执行机构,分别设计阻尼模式、保持模式和换道模式控制器.其中保持模式引入了一种控制预瞄点处侧向偏差的一阶导数和二阶导数的方法,不但有效地防止了超调,而且减少了车辆回到车道中心线的时间;换道模式利用模型预测控制算法,加入多个约束,提高了车辆换道过程的稳定性.从混杂系统稳定性的角度出发,设计了简单有效的稳定性监督器,防止车辆失稳.最后,在Car Sim/Simulink联合仿真平台及Car Sim/Lab VIEW硬件在环测试平台上验证了本方法的有效性和切换过程的稳定性.

Through the analysis of the main types of accidents and three basic driving behavior in high-speed condition, it was concluded that steering system has both discrete state and continuous state. And then a multi-mode-switching control strategy was proposed, which used time to line crossing （TLC） and safe distance as switching rules. The damping, lane-keeping and lane-changing controller were designed respectively and were implemented on steer-by-wire system. In lane-keeping model, a new method is introduced to control the first derivative and the second derivative of the lateral offset of the preview point, which can not only prevent the excessive overshoot, but also reduce the time for the vehicle to return to the central line of the lane. The lane-changing model used the model predictive control （MPC） with multiple constraints to improve the stability of vehicle lane changing process. Based on the stability theory of hybrid system, a simple but effective stability supervisor was designed to prevent vehicle from the loss of control. Finally, the proposed control method is implemented on CarSim/Simulink and hardware-in-loop test platform, and the results proved the effectiveness of this strategy, and the stability of the switching process.