智能电动汽车自适应巡航分层控制研究

Hierarchical Control of Adaptive Cruise System ofIntelligent Electric Vehicle

针对前车频繁变速而引起的电动车跟踪性差的问题,建立基于分层控制的自适应巡航控制系统。首先,考虑前车加减速变化的影响,采用可变时距策略作为期望安全车距,利用多项式拟合法分析不同车间时距对线性二次型最优控制算法的反馈增益矩阵的影响,建立基于改进线性二次型最优控制的上层控制器;然后,应用分数阶PID控制理论建立下层控制器,对期望驱动转矩和制动压力进行精确跟踪,并采用遗传优化算法寻优整定分数阶PID参数。研究表明:基于分层控制建立的自适应巡航控制器能保证车辆行驶安全性和舒适性,对前车频繁加减速工况具有较好的适应性,跟踪性能好。

Aiming at the problem of poor tracking of electric vehicles caused by frequent shifts of the preceding vehicle,an adaptive cruise control system based on hierarchical control was established.Firstly,considering the influence of the acceleration and deceleration changes of the preceding vehicle,the variable headway strategy was adopted as the expected safe vehicle distance,and the polynomial fitting method was used to analyze the influence of different vehicle time interval on the feedback gain matrix of the linear quadratic optimal control algorithm and build an upper-level controller based on improved linear quadratic optimal control.Then,the fractional PID control theory was applied to establish the lower controller to accurately track the expected driving torque and braking pressure,and genetic optimization algorithm was used to optimize and adjust the fractional PID parameters.The research shows that the adaptive cruise controller based on hierarchical control can ensure the safety and comfort of the vehicle,which has good adaptability to the frequent acceleration and deceleration conditions of the preceding vehicle and has good tracking performance.