Xiong Xiaoyong, Min Haitao, Yu Yuanbin, Wang Pengyu
State Key Laboratory of Automotive Simulation and Control, Jilin University, No. 5988, Renmin Street, Changchun, Jilin 130022, China.
Math Biosci Eng. 2020 Nov 17;18(1):1-21. doi: 10.3934/mbe.2021001.
Trajectory planning is one of the key technologies for autonomous driving. A* algorithm is a classical trajectory planning algorithm that has good results in the field of robot path planning. However, there are still some practical problems to be solved when the algorithm is applied to vehicles, such as the algorithm fails to consider the vehicle contours, the planned path is not smooth, and it lacks speed planning. In order to solve these problems, this paper proposes a path processing method and a path tracking method for the A* algorithm. First, the method of configuring safe redundancy space is given considering the vehicle contour, then, the path is generated based on A* algorithm and smoothed using Bessel curve, and the speed is planned based on the curvature of the path. The trajectory tracking algorithm in this paper is based on an expert system and pure tracking theory. In terms of speed tracking, an expert system for the acceleration characteristics of the vehicle is constructed and used as a priori information for speed control, and good results are obtained. In terms of path tracking, the required steering wheel angle is calculated based on pure tracking theory, and the influence factor of speed on steering is obtained from test data, based on which the steering wheel angle is corrected and the accuracy of path tracking is improved. In addition, this paper proposes a target point selection method for the pure tracking algorithm to improve the stability of vehicle directional control. Finally, a simulation analysis of the proposed method is performed. The results show that the method can improve the applicability of the A* algorithm in automated vehicle planning.
轨迹规划是自动驾驶的关键技术之一。A算法是一种经典的轨迹规划算法，在机器人路径规划领域取得了良好的效果。然而，该算法应用于车辆时仍存在一些实际问题需要解决，比如算法未考虑车辆轮廓、规划路径不光滑以及缺乏速度规划等。为了解决这些问题，本文提出了一种针对A算法的路径处理方法和路径跟踪方法。首先，考虑车辆轮廓给出配置安全冗余空间的方法，然后基于A算法生成路径并使用贝塞尔曲线进行平滑处理，同时根据路径曲率规划速度。本文的轨迹跟踪算法基于专家系统和纯跟踪理论。在速度跟踪方面，构建了车辆加速度特性的专家系统并将其用作速度控制的先验信息，取得了良好的效果。在路径跟踪方面，基于纯跟踪理论计算所需的方向盘角度，并从测试数据中获取速度对转向的影响因素，在此基础上对方向盘角度进行校正，提高了路径跟踪的精度。此外，本文还提出了一种针对纯跟踪算法的目标点选择方法，以提高车辆方向控制的稳定性。最后，对所提方法进行了仿真分析。结果表明，该方法能够提高A算法在自动驾驶车辆规划中的适用性。
