基于遗传算法的四轮转向-驱动汽车时变LQR控制

Time-Varying LQR Control of Four-Wheel Steer/Drive Vehicle Based on Genetic Algorithm

四轮转向-驱动汽车相较于传统车辆能保证四轮转角/转矩独立可控,具有十分优异的主动动力学控制性能。文中针对四轮转向-驱动汽车转角转矩的协调控制提出了一种基于遗传算法的时变LQR控制系统。该系统区别于传统的线性化轮胎参考模型,考虑轮胎的变刚度特性建立线性时变系统,并利用遗传算法对状态量的控制权重矩阵进行优化。仿真结果表明,在给定的转角阶跃输入下,考虑轮胎非线性特性的时变LQR控制系统相较于线性化模型控制系统,对质心侧偏角的零化效果更优异,横摆角速度对理想值的跟踪精度提升3.01%。在高速低附路面下的双移线工况仿真表明,基于遗传算法的时变LQR控制系统能确保车辆具有较好的轨迹跟踪能力,最大侧向位移误差控制效果相较于前轮转向车辆提升44%。

As compared with traditional vehicles,four-wheel steer/drive vehicles have very good active dynamics control performance,ensuring that the four-wheel steering/torque is independently controllable.This article proposed a time-varying LQR control system based on genetic algorithm for the coordinated control of the steering angle-torque of four-wheel steer/drive vehicles.Different from the traditional linearized tire reference model,it esta-blished a linear time-varying system considering the variable stiffness characteristics of the tire,and the control weight matrix of the state quantity was optimized with the genetic algorithm.The simulation results show that under a given corner step input,the time-varying LQR control considering the non-linear characteristics of the tire is be-tter than the linearized model control system in zeroing the center of mass sideslip angle,and the tracking accuracy of the yaw rate with ideal value is improved by 3.01%.The simulation of the double line change under high speed and low road conditions shows that the time-varying LQR control system based on genetic algorithm ensures a better trajectory tracking ability of the vehicle,and the maximum lateral displacement error control effect is improved by 44%,compared with that of front-wheel steering vehicles.