紧急制动下车身姿态的控制研究

Study of Body Posture Control on Emergency Braking

考虑到车辆行驶过程中遇突发状况紧急制动会引起车身姿态较大幅度地变化,同时受路面附着系数、道路条件等影响车轮也会发生抱死和侧滑。为了提高车辆在紧急制动工况下的平顺性和制动性能,改善车身姿态的变化,对非线性半车模型进行了研究,建立了包含主动悬架与制动在内的仿真模型,在主动悬架LQG控制、目标滑移率模糊控制的基础上,通过两者之间的相互影响,进一步设计了俯仰模糊控制策略来改善车身姿态。对车辆在不同控制下紧急制动进行了动力学仿真分析,结果表明,联合控制能够较好地抑制车辆俯仰角的变化,加大制动减速度,减小车身垂直加速度和制动时间,改善车辆的性能,证明设计的控制策略是有效的。

Given the case of a sudden condition,emergency braking causes greater changes of body posture during driving.Meanwhile,wheels are locked and slewed on the effect of road adhesion coefficient as well as road condition. In order to enhance ride comfort and braking performance of vehicle under emergency braking condition,as well as improve the body posture,study is carried out on a nonlinear half-car model by building simulation model of active suspension and braking system. On the basis of designing LQG control for active suspension,fuzzy control based on the aim slip ratio,a pitch fuzzy control strategy is further designed to improve the body posture through the interaction between two systems. The dynamic simulation of emergency braking is analyzed under different control. According to the simulation results,the combined control can betterly restraint changes of pitch angle,increase braking deceleration and reduce body vertical acceleration as well as braking time,which improve vehicle performance. And thus the designed control strategy is proved to be effective.