复杂路况下高速行驶汽车防抱死制动系统滑移率最优跟踪控制

Research on optimal tracking control for ABS slip ratio of high speed vehicle in complex road conditions

为了研究在复杂路况下高速行驶汽车能稳定制动的控制策略,基于防抱死制动系统(ABS)滑移率非线性动力学模型,以滑移率误差及其变化率综合最优为控制目标,利用极小值原理推导出制动时最优滑移率的解析解,进而利用制动减速度、制动车速、车轮角速度等反馈信号,在无需复杂路况附着系数信息的前提下,计算制动控制扭矩,建立ABS滑移率最优跟踪控制方法.利用Matlab/Simulink软件,对不同复杂行驶路况下目标滑移率的最优跟踪控制效果进行了仿真验证,发现实际滑移率均能在任意规定的时刻与目标滑移率同步;而同步过程的滑移率误差仅取决于滑移率误差权值与误差变化率权值的比值和制动初始时刻的滑移率误差.所建立的控制方法能保证在复杂路况行驶的任意时刻较为快速、精准、稳定地完成最优制动控制.

For the purpose of investigating control strategy of making high speed vehicle brake steadily in complex road conditions,an affine nonlinear dynamic model of anti-lock braking system (ABS) slip ratio is built.Then,comprehensive optimization of slip ratio error with its changing rate is taken as control objective,and analytical solutions of optimal slip ratio and control torque are derived through minimum principle.And then,real time cooperative computation of brake torque without any adhension coefficient information of complex road conditions can be accomplished by utilizing analytical solution of optimal slip ratio with feedback signals such as brake deceleration,brake speed of vehicle and angular velocity of tire.Therefore,an optimal tracking control method for ABS slip ratio of high speed vehicle in complex road conditions and disturbances is established.Through Matlab/Simulink numerical evaluation of effect of proposed optimal control for tracing different objective slip ratio in different complex road conditions,it can be observed that the target slip ratio can be synchronized with actual slip ratio at any specified time,and also slip ratio error is determined by its initial value and ratio between weight of slip ratio error and that of its change rate in control objective functional.Consequently,it can be concluded that steady accomplishment of such rapid and precise brake action in complex road conditions at any time is feasible.