可变附着系数路面上的自动紧急制动避撞安全策略研究

Research on Safety Strategy for Collision Avoidance by Automatic Emergency Braking on a Road with Varying Adhesion Coefficient

针对路面条件变化时紧急制动系统易出现的制动时机决策失准问题,提出基于车辆运动学的动态决策增强安全模型的紧急制动策略。首先,依据目标车加减速状态细化工况,基于车辆速度与加速度建立动态决策安全模型,以提高极端工况下控制策略对车辆动态行驶速度的适应性。接着,以无迹卡尔曼滤波(UKF)算法连续辨识获得道路附着系数,通过系列道路条件下对实车和模型的制动性能试验建立路况与车辆减速能力的关系,根据道路条件实时更新模型依赖的极限减速度参数,进一步增强控制策略安全性和对动态道路条件的适应性。最后,通过附着系数连续多变路面工况试验和中国新车评价规程(C-NCAP)测试工况试验,对控制策略进行验证。结果表明,滤波算法具备精准的辨识效果;而自动紧急制动策略可在变化附着系数路面上实现对制动时机的准确决断。

In view of that the emergency braking system is prone to making an inaccurate decision on braking timing when road conditions change,an emergency braking strategy is proposed based on enhanced safety model with dynamic decision-making on vehicle kinematics.Firstly,a dynamic decision-making safety model is established based on vehicles’speed and acceleration under the subdivided working conditions of the acceleration and deceleration states of target vehicle,so as to enhance the adaptability of the control strategy to the dynamic driving speed of the vehicle in extreme working conditions.Then,the road adhesion coefficient is obtained by continuous identification using unscented Kalman filter(UKF)algorithm,the relationship between road conditions and vehicle deceleration capability is established through braking performance tests on both real vehicle and model under a series of road conditions,and the model-dependent extreme deceleration parameters are updated real time according to road conditions,which further enhances the safety of control strategy and its adaptability to dynamic road conditions.Finally,the control strategy is verified through both the test on the road with continuously varying adhesion coefficient and C-NCAP test,and the results show that the UKF algorithm can get accurate identification results and the automatic emergency braking strategy can make the accurate decision on braking timing on the road with varying adhesion coefficient.