电动汽车碰撞失稳条件下运动轨迹瞬时规划与控制方法研究

Collisions of light (or lightweight) electric vehicles will cause large hurts to the passengers, due to their small qualities, and simultaneously, easily bring about the displacement or damage and thus the combustion to the battery, due to small crumple zones. Statistics show that after a first collision, a vehicle has high probability for a secondary collision, which will cause much larger harm to the passengers. In order to effectively reduce the probability of the secondary collision for light electric vehicles after losing stability cause by the tailgates or side-impacts, this project focuses on the dynamics control issues for vehicle losing stability after collision, and schemes the following work: (1) the dynamics modeling and analysis for vehicle after losing stability, systematically analyze the dynamic characteristics of the wheel, wheel-axle and whole car after stability losing, and design the criterion for the loss of stability; (2) design estimation methods for the collision characteristics based on the changes of the vehicle body states, study the states prediction and the optimal-trajectory planning issues after vehicle stability loss, and select the optimal, achievable vehicle state and driving trajectory with considering the tire forces limits; (3) explore the vehicle states and control strategies after vehicle stability loss, with combining the active steering system and direct yaw moment control, study the control allocation methods for vehicle chassis in extreme conditions. The proposed research in this project can effectively reduce the second-collision probability for light electric vehicles after losing stability, and decrease the harm to passengers caused by the unavoidable crash.

电动汽车结构紧凑质量轻，碰撞时乘员和电池保护难度大。现有研究主要集中于电动汽车首次碰撞安全性，然而碰撞车辆失稳后状态高度不确定性、运动轨迹控制困难，极易导致二次碰撞的更大伤害。本课题围绕电动汽车碰撞失稳条件下运动轨迹规划与避撞控制问题开展研究：1）研究车辆失控后车轮、车轴及整车的动力学多参数响应机理，基于多传感器融合原理构造碰撞失稳状态的新判据；2）研究车辆失稳后的连续运动过程中的轨迹估计和瞬态规划方法，快速获得碰撞后车身最优、可达的运动轨迹；3）研究极限运动状态下车辆动力学控制与控制量快速分配方法，结合主动转向和直接横摆力矩控制实现车辆失稳后避撞轨迹的精确控制；4）通过四轮主动控制的电动汽车试验平台验证，形成失稳条件下运动轨迹瞬时规划与极限控制新方法，有效减少二次碰撞发生的可能性。课题的研究对各类车辆失稳后的过驱动非线性系统控制研究也有理论借鉴意义。

为减小轻型电动汽车碰撞失稳后后继碰撞概率和降低碰撞危害，本项目研究了车辆失稳后姿态和轨迹的规划和运动控制问题。项目建立了车辆失稳后的动力学模型，能基于车辆碰撞后的初始状态预估车辆失稳后的运动状态和轨迹，并给出了可低成本实现的车辆稳定性判据；给出了能失稳后车辆最优的、可达的姿态和轨迹的规划方法；设计了车辆失稳后的运动控制方法，确保预期控制目标能被实现，从而减小了车辆失控后发生后继碰撞概率，降低了碰撞伤害；搭建了实验车，该车配备了主动转向系统且四个车轮由四个电机独立驱动和制动，可实时、准确给出期望的轮胎纵向力和转向角，该实验平台可用于车辆动力性能测试。 项目的执行，给出了失稳条件下运动轨迹瞬时规划与极限控制新方法，可有效减少二次碰撞发生的可能性，对各类车辆失稳后系统控制研究也有借鉴意义。