School of Ocean Science and Technology, Dalian University of Technology, Panjin 124221, China.
Leicester International Institute, Dalian University of Technology, Panjin 124221, China.
Sensors (Basel). 2022 Jul 11;22(14):5181. doi: 10.3390/s22145181.
The aim of local path planning for unmanned surface vehicles (USVs) is to avoid unknown dynamic or static obstacles. However, current relative studies have not fully considered the impact of ocean environmental factors which significantly increase the control difficulty and collision risk of USVs. Therefore, this work studies two ocean environmental factors, namely, wave and current, given that they both have a significant impact on USVs. Furthermore, we redesign a kinematic model of an USV and the evaluation function of a classical and practical local path planning method based on the dynamic window approach (DWA). As shown by the results of the simulations, the path length was impacted mainly by the intensity of the environmental load and slightly by the direction of the environmental load, but the navigation time was significantly influenced by both. Taking the situation in still water as a benchmark in terms of the intensity and direction of the environmental factors, the maximum change rates of the path length were 8.6% and 0.6%, respectively, but the maximum change rates of the navigating time were 17.9% and 25.6%, separately. In addition, the average calculation time of each cycle was only 0.0418 s, and the longest time did not exceed the simulation time corresponding to a single cycle of 0.1 s. This method has proven to be a good candidate for real-time local path planning of USVs since it systematically considers the impact of waves and currents on the navigation of USVs, and thus ensures that USVs can adjust to the planned path in time and avoid obstacles when navigating in the real ocean environment.
无人水面艇（USV）的局部路径规划旨在避免未知的动态或静态障碍物。然而，当前的相关研究尚未充分考虑海洋环境因素的影响，这些因素显著增加了 USV 的控制难度和碰撞风险。因此，这项工作研究了两个海洋环境因素，即波浪和海流，因为它们都对 USV 有重大影响。此外，我们重新设计了 USV 的运动学模型和基于动态窗口方法（DWA）的经典实用局部路径规划方法的评估函数。模拟结果表明，路径长度主要受环境负荷强度的影响，而受环境负荷方向的影响较小，但导航时间则受到两者的显著影响。以静水中的情况为基准，环境因素的强度和方向的最大变化率分别为 8.6%和 0.6%，但导航时间的最大变化率分别为 17.9%和 25.6%。此外，每个周期的平均计算时间仅为 0.0418 s，最长时间不超过与 0.1 s 单周期对应的模拟时间。由于该方法系统地考虑了波浪和海流对 USV 航行的影响，从而确保 USV 可以在实时海洋环境中及时调整到规划路径并避免障碍物，因此它被证明是 USV 实时局部路径规划的一个很好的候选方案。
