高速公路上自动超车过程的轨迹规划与跟踪控制

doi:10.3969/j.issn.1674-8484.2022.03.007

摘要/Abstract

摘要：

研究了自动驾驶汽车在高速公路上超车过程中的轨迹规划和跟踪控制。基于纵向位移与时间（s-t）图,对超车过程进行建模和数字仿真分析,并应用多项式来规划车辆横纵向运动。采用集中式模型预测控制器,综合控制车辆横纵向的运动,以实现超车过程的轨迹跟踪。结果表明：相较于分散式控制方法,利用集中式控制方法下的车辆侧向加速度的整体波动减小19.0%,横摆角速度的整体波动减小11.6%。因而,集中式控制方法下的横向运动偏差更小,纵向加速过程更加平滑、稳定,符合高速公路超车过程安全平稳性的要求。

关键词: 汽车安全, 自动驾驶汽车, 超车模型, 轨迹规划, 跟踪控制

Abstract:

The trajectory planning and tracking control were investigated in the overtaking process for the autonomous driving vehicles on highway. The overtaking process was modeled and analyzed by digital simulation through longitudinal displacement-time graph (s-t graph). The algorithm planned the vehicle’s longitudinal and lateral motion with polynomials. The centralized model predictive controller controlled the vehicle’s longitudinal and lateral motion to realize the trajectory tracking of the overtaking process. The results show that compared to the decentralized control method, the centralized control method decreases the vehicle lateral acceleration fluctuation by 19.0%, and decreases the vehicle yaw rate fluctuation by 11.6%. Therefore, the centralized control method has smaller deviations in the lateral motion with smoother and more stable longitudinal accelerations. Thus, it meets the basic safety and stability requirements at highway overtaking.

Key words: car safety, autonomous driving vehicles, overtaking model, trajectory planning, tracking control

中图分类号:

U461.6

张平, 陈一凡, 江书真, 韩毅. 高速公路上自动超车过程的轨迹规划与跟踪控制[J]. 汽车安全与节能学报, 2022, 13(3): 463-472.

ZHANG Ping, CHEN Yifan, JIANG Shuzhen, HAN Yi. Trajectory planning and tracking control of automatic overtaking process on highway[J]. Journal of Automotive Safety and Energy, 2022, 13(3): 463-472.

图/表 18

图1 3阶段超车模型

图2 高速公路换道模型

图3 换道阶段s-t图

图4 Frenet坐标系

图5 横向轨迹备选集合

图6 纵向轨迹备选集合

图7 模型预测控制流程

图8 三自由度车辆动力学模型

图9 节气门开度和制动压力的计算模型

图10 驱动/制动切换逻辑曲线

图11 CarSim和Matlab/Simulink联合仿真平台

质量,m	1.35 t
轴距,L	2.60 m
前轴到质心的距离,l_f	1.04 m
后轴到质心的距离,l_r	1.56 m
转动惯量,I_z	1.538 t·m²

表1 车辆仿真参数

预测时域,N_p	40
控制时域,N_c	20
采样间隔,∆T	100 ms
状态加权矩阵,Q	10I_Nx
控制加权矩阵,R	I_Nu
松弛因子权重系数,w	10
Jerk权重系数,k_j	1.0
规划时长权重系数,k_t	0.1
横向偏差权重系数,k_d	1.0
横向损失函数权重系数,K_d	1.0
纵向损失函数权重系数,K_s	1.0

表2 控制器仿真参数

图12 仿真场景1的换道可行性分析

图13 车辆参考轨迹和仿真轨迹

图14 车辆纵向速度曲线

图15 车辆侧向加速度曲线

图16 车辆横摆角速度曲线

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