基于三维势场模型的船舶局部路径规划方法

Study on local path planning method for ships based on three-dimensional potential field model

  • 摘要:
    目的 为使局部路径规划算法更加符合船舶操纵特性,生成的参考路径更加安全可靠,提出了一种三维势场的建模方法。
    方法 将笛卡尔坐标系转换为椭球体坐标系解决势场分布函数的各向同性问题,通过求解拉普拉斯方程计算船舶势能分布函数,设计了势场模型和模型预测控制(MPC)算法相结合的控制框架,提升不同场景下的船舶动态实时局部路径规划的适应性。以苏通长江公路大桥桥区水域实际航行船舶为仿真对象,采用三维势场模型获取局部参考路径,结合MPC算法进行船舶路径跟踪控制仿真试验。
    结果 结果表明,在单船对遇场景、单船交叉会遇场景以及多船场景下,相较于传统人工势场和改进人工势场生成的参考路径,三维势场模型的局部参考路径长度、曲线平滑度、最大转向角度、平均绝对航向误差整体表现最优。可以生成距离更短、更平滑的局部路径,且更加符合船舶实际操纵习惯,在交通流量密集的场景下的抖动更加轻微。
    结论 三维势场模型生成的局部参考路径可以有效识别目标船舶转向角度和船舶尺度差异,降低对周围目标船舶数量的依赖,并能有效获取船舶智能体之间的相互作用,具有较高的可靠性。

     

    Abstract:
    Objectives To make local path planning algorithms more consistent with the maneuvering characteristics of ships, thereby generating safer and more reliable reference paths.
    Methods This paper proposes a three-dimensional potential field modeling method. By converting the Cartesian coordinate system to the ellipsoidal coordinate system, it addresses the anisotropy problem of the potential field distribution function. The ship’s potential energy distribution function is calculated by solving the Laplace equation. A control framework combining the potential field model and Model Predictive Control (MPC) algorithm is designed to enhance the adaptability of dynamic real-time local path planning for ships in different scenarios. Simulations were conducted with actual navigation vessels in the waters of the Sutong Yangtze River Highway Bridge area. The three-dimensional potential field model was used to obtain local reference paths, and MPC algorithm was employed for ship path tracking control simulation experiments.
    Results  The results show that, compared to reference paths generated by traditional artificial potential field and improved artificial potential field methods, the three-dimensional potential field model’s local reference paths are superior in terms of length, curve smoothness, maximum steering angle, and average absolute heading error. This model can generate shorter and smoother local paths, which are more consistent with the actual maneuvering habits of ships, and exhibit less jitter in traffic-intensive scenarios.
    Conclusions The study demonstrates that the local reference paths generated by the three-dimensional potential field model can effectively identify the target ship’s steering angles and differences in ship scale, reduce reliance on the number of surrounding target ships, and effectively capture the interactions between ship agents, thus showing high reliability.

     

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