多轮独立电驱动车辆过驱动耦合解析与转矩控制分配研究

Electric vehicle with eight in-wheel motors has some advantages. However, the redundancy of its driving system leads to a nonlinear coupling relationship from the traction of each motor, which falsify the independent multi driving force distribution and leads to problems of bad handling and stability, serious wheel slip and slide. This work aims at doing research on the problem of the driving interference. This work will analyze the multi-drive vehicle dynamics coupling relations to establish the dynamics model of multi-degree of freedom. Considering friction limits, a moderated particle reference model (MPR) theory is further improved in the studies of the earlier stage for the vehicle system with redundant actuators. A nonlinear multi-degree-of-freedom dynamics model of the 8×8 vehicle, based on the above theory, is going to be established for analyzing the nonlinear dynamics characteristics of its driving system. The driving mode control strategy is firstly introduced for the hypostatic electric vehicle with multi-in-wheel motors. Drive mode/configuration of eight in-wheel motored vehicle is determined by considering vehicle dynamics performance and energy efficiency and, in details, the factors influencing yaw moment generated by the tire longitudinal/lateral forces should be taken into consideration, such as vertical load transfer, direction of yaw moment generated by the longitudinal/lateral force of each tire, and the effective working range of steering control and driving/braking control. A hierarchical vehicle dynamic control structure is proposed to ensure the energy efficiency optimization. Finally, torque distribution control strategy will be realized by using the nonlinear sliding mode control method and control allocation method considering the tire constraints. This strategy could realize the integrated control for the multi-in-wheel independent derived electric vehicles which would solve the interference problem about the overactuated system. Moreover, the feasibility and effectiveness of the models and strategies proposed will be verified by the application of simulation, bench and real vehicle.

8×8轮毂电机驱动车辆具有布置灵活、传动效率高、通过性强等优势，但冗余的驱动装置会引起驱动力的非线性耦合增强，导致过驱动车辆的转矩分配失准而引起车辆稳定性和系统效率降低问题。本项目将研究此驱动系统干涉的问题，分析多路驱动车辆动力学耦合关系，建立过驱动车辆多自由度动力学模型；进一步完善自协调粒子参考模型理论，建立8×8轮毂驱动车辆的非线性多自由度动力学模型,开展系统动力学特性分析；提出过驱动多轮车辆驱动模式控制策略，结合轮毂电机的动态转矩特性与效率特性，基于载荷转移、横摆力矩控制、轮/轴间驱动与制动非线性关系实现驱动模式的动态选择；最终在考虑传动效率优化的基础上，提出分层车辆动力学控制结构，利用非线性滑模控制和包含轮胎约束的控制分配方法，实现八轮驱动力矩全局协同规划控制，从而解决过驱动系统干涉问题，并应用仿真、台架和实车等方式验证该策略的有效性，最终提供车辆行驶的稳定性和平顺性。

8×8轮毂电机驱动车辆具有布置灵活、传动效率高、通过性强等优势，但冗余的驱动装置会引起驱动力的非线性耦合增强，导致过驱动车辆的转矩分配失准而引起车辆稳定性和系统效率降低问题。本项目将研究此驱动系统干涉与车辆稳定性控制的问题，分析多路驱动车辆动力学耦合关系，建立过驱动车辆多自由度动力学模型；建立8×8轮毂驱动车辆的非线性多自由度动力学模型,开展系统动力学特性分析；提出过驱动多轮车辆驱动模式控制策略，深入分析以永磁同步电机转矩脉动控制对车辆稳定性影响，基于载荷转移、横摆力矩控制、轮/轴间驱动与制动非线性关系实现驱动模式的动态选择；最终在考虑传动效率优化的基础上，提出分层车辆动力学控制结构，利用非线性滑模控制和包含轮胎约束的控制分配方法，实现八轮驱动力矩全局协同规划控制，从而解决过驱动系统干涉问题，并应用仿真、台架和实车等方式验证该策略的有效性，最终提供车辆行驶的稳定性和平顺性。