基于混杂理论的电磁与摩擦集成制动方法

鉴于传统电子液压制动系统连续制动易产生“热衰退”现象,结构缺陷导致的制动响应慢,制动系统与电控系统衔接差等缺点,提出了一种基于混杂自动机模型的电磁与摩擦集成制动方法.首先分析集成制动器制动时的工作特点以及不同情况下对应的工作模式(纯电磁制动、纯摩擦制动以及集成制动),并确定3种制动模式的切换条件,通过逻辑门限算法将其实现.根据制动时车辆既具有连续运动状态又有离散状态的混杂特性,使用MATLAB/Stateflow建立基于制动模式切换系统的推广自动机模型,并根据制动模式切换控制策略,对3种制动模式切换进行试验,验证制动模式切换控制策略的合理性.最后选取车辆制动初速度为28m· s^-1的直线制动工况,分别在高附着系数(0.85)以及低附着系数(0.3)的路面条件下,通过试验平台对控制算法和制动系统性能进行试验验证.研究结果表明:所提出的汽车混杂理论模型以及优化方法在在低附着系数(0.3)路面条件下,集成制动方法较传统液压制动系统缩短5.12%的制动距离,缩短制动时间0.3s;在高附着系数(0.85)路面条件下,集成制动方法较传统液压制动系统缩短5.66%的制动距离,缩短制动时间0.2s,能有效提高制动效能.

Electromagnetic and Friction Integrated Braking Method Based on Hybrid Theory

In view of the shortcomings of traditional electronic hydraulic brake systems, such as "heat-fading" and slow braking response caused by structural defects and poor connection to the electronic control system, a hybrid automatic braking method based on hybrid automata model is proposed. Firstly, the working characteristics of the integrated brake and corresponding working modes under different conditions were analyzed, that is, pure electromagnetic braking and pure friction braking, and three kinds of brake mode switching conditions were determined; this was realized by a logic threshold algorithm. According to the hybrid characteristics of both the continuous motion state and discrete state when the vehicle is braking, a generalized automation model based on the brake mode switching system was established using MATLAB and Stateflow. The traditional continuous system optimization method is not suitable for hybrid systems, and the switching characteristics of the braking system control strategy are under sectional gradient. The system was optimized by the descending method. Finally, the linear braking condition of the vehicle braking speed was determined as 28 m·s^-1, and the test platform was used to test the control algorithm and braking system performance under high and low adhesion coefficients of 0.85 and 0.3, respectively. The results show that under low adhesion coefficient (0.3), the proposed hybrid theoretical model and optimization method can shorten the braking distance of the traditional hydraulic brake system by 5.12% as well as reduce the braking time 0.3 s. Under the condition of high adhesion coefficient (0.85), the integrated braking method shortens the braking distance by 5.66% compared with the traditional hydraulic brake system and reduces the braking time 0.2 s, which effectively improves braking efficiency.