非对称路面对制动效能影响的仿真分析

针对传统制动性能分析并未涉及路面因素,提出将路面激励非对称度作为制动性能影响因子,利用Carsim联合Simulink对非对称路面下车辆制动效能进行仿真分析。以典型路面激励作为参考基准,在Simulink中构建路面激励可控的车辆制动模型。为保证前后车轮能够以相同概率遍历同一路面,依据车速和轴距确定时间延迟;根据模型计算出的当量方向盘转角界定非稳态制动跑偏,对不同路面激励下的制动减速度、制动距离进行仿真分析;并对路面激励的相关系数与跑偏车速以及制动衰减时间之间的关系进行分析。结果表明:在车速一定情况下,路面的非对称度与制动减速度波动性正相关,与制动距离负相关,且左右路面存在非对称度时,车辆更容易达到非稳态跑偏的临界车速,制动衰减时间与跑偏车速对相关系数在0~0.2内的路面激励特别敏感。

Simulation and Analysis of Non-symmetrical Road Impact on Brake Performance

Because traditional brake performance analysis did not involve in road factors,this paper proposes that non-symmetrical degree of road input should be as an influence factor of brake performance and simulink united with carsim are used to simulate and analyse brake efficiency under non-symmetrical road input.The representative road input is to be as reference and vehicle brake model which road input can be controlled is established in simulink.Speed and axle distance are adopted to determine time delay so that the front and rear tires can go through the same road surface at the same probability.The equivalent steering wheel angle calculated by the model is used to define non-stable brake deflection.Then,brake acceleration and brake distance under different road inputs are simulated and analysed and the relationship among relevant coefficient,brake deflection speed and brake decay time is simulated and analysed.The results show that non-symmetrical degree of road input is positive relevance with brake acceleration fluctuation and is negative relevance with brake distance.Moreover,if the left and right road surfaces are not symmetrical,vehicle can more easily achieve non-stable brake deflection critical speed.Brake decay time and deflection speed are more sensitive to road input which relevant coefficient varies from 0 and 0.2.