四轮独立驱动汽车偏转 差动协同转向路径跟踪

Research on trajectory tracking of deflection-differential coordinated steering for four-wheel independent drive vehicles

为改善四轮独立驱动汽车在不同车速与路面附着系数下的路径跟踪效果,提出了偏转差动协同转向控制策略。在二自由度动力学模型的基础上,建立多点预瞄与线性二次调节(LQR)结合的前轮偏转转向路径跟踪、滑模控制与四轮转矩优化分配结合的四轮差动转向路径跟踪,采用模糊控制对偏转转向与差动转向路径跟踪的权重进行自适应分配,建立包含路径跟踪层与转角、转矩分配控制层的偏转差动协同控制策略。利用Carsim与Simulink分别建立协同转向路径跟踪与LQR偏转转向路径跟踪联合仿真平台,取车速为54、72 km/h与路面附着系数为0.3、0.8的双移线工况进行仿真得出结论:相较于LQR偏转转向路径跟踪,协同转向路径跟踪在各工况下的横向跟踪精度与稳定性均有所提高。

To improve the path tracking performance of four-wheel independent drive vehicles under different speeds and tire-road friction coefficients,this paper designs a path tracking strategy through the collaboration of deflection steering and differential steering.Based on the 2DOF dynamic model,the front wheel deflection steering path tracking strategy is built by multi-point preview and linear quadratic regulator(LQR),and the four wheel differential steering path tracking strategy is built by sliding mode control and four wheel torque optimization allocation.Fuzzy control is adopted to achieve the adaptive weight allocation of deflection and differential steering.The deflection-differential collaborative control strategy is built,consisting of a path tracking layer,a steering angle and torque allocation control layer.A co-simulation platform is also built for collaborative steering path tracking control and LQR deflection steering path tracking control using Carsim and Simulink.Simulations are conducted under double lane changing conditions with a speed of 54 km/h or 72 km/h and a road tire-road friction coefficient of 0.3 or 0.8.Our results indicate the collaborative steering path tracking improves both stability and lateral tracking accuracy under all operating conditions compared with LQR deflection steering path tracking.