Fuzzy dual-window DWA algorithm for USV in dense obstacle conditions
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摘要:
目的 旨在研究密集障碍物海况下无人艇的自主避障问题。 方法 为此,提出一种基于模糊推理的改进型双窗口动态窗口法(DWA)避障算法,即在常规速度窗口的基础上设计基于艇载传感器的感知窗口,构成双窗口模型以进一步优化约束速度空间,然后根据障碍物的分布,动态调整评价函数权值。 结果 仿真实验结果显示,相比原始DWA算法,改进算法在未知密集障碍物海况下规划的路径更加合理、光滑,可避免无人艇从密集障碍物群外绕行,同时确保了避障航行安全性,迭代次数和运行时间可缩短20%以上。 结论 研究成果对无人艇自主避障技术发展具有较为明显的科学价值和实际意义。 Abstract:Objectives The problem of autonomous obstacle avoidance of unmanned surface vehicles (USV) under dense obstacle sea conditions is studied. Methods An improved dual-window dynamic window approach (DWA) obstacle avoidance algorithm based on a fuzzy control strategy is proposed; that is, a sensing window based on an onboard sensor is designed on the basis of the conventional speed window, and a dual-window model composed of the speed window and sensing window is further optimized. The speed space is constrained and the weight of the evaluation function is dynamically adjusted based on the fuzzy control strategy in accordance with the obstacle distribution state and distance between the USV and obstacles. Results The simulation experimental results show that, compared with the original DWA algorithm, the path planned by the improved algorithm under unknown dense obstacle sea conditions is smoother and more reasonable, which not only solves the problem of USVs detouring outside dense obstacle groups, but also improves the safety of obstacle avoidance navigation and reduces the number of iterations and running time by more than 20%. Conclusions The results of this study have certain reference value for research on the autonomous obstacle avoidance technology of USVs. -
表 1 实验结果数据
Table 1. Experimental result data
参数 轨迹长度/m 运行时间/s 安全距离/m α=2,β=1,γ=15 155.90 12.259 0.45 α=2,β=15,γ=15 158.40 13.835 2.41 表 2 模糊逻辑控制输入输出子集
Table 2. Fuzzy logic control input and output subset
变量 模糊子集 输入 $D$ 小(S)、中(M)、大(H) $I$ 小(S)、大(H) 输出 $\gamma $ 小(S)、中(M)、大(H) $\beta $ 小(S)、中(M)、大(H) 表 3 输出量
$\gamma $ 的模糊规则Table 3. Fuzzy rules of γ
$\gamma $ I S H $D{\rm{ = }}S$ H S $D{\rm{ = }}M$ H S $D{\rm{ = }}H$ H H 表 4 输出量
$\;\beta $ 的模糊规则Table 4. Fuzzy rules of β
$\beta $ I S H $D{\rm{ = }}S$ S H $D{\rm{ = }}M$ S M $D{\rm{ = }}H$ S M 表 5 无人艇速度限制
Table 5. Speed limit of USV
参数 数值 最小前进速度$ {u_{\min }}/ $(m·s−1) 0 最大前进速度${u_{\max }}/$(m·s−1) 1.5 前进加速度$\dot u/$(m·s−2) 0.5 最小艏摇角速度${r_{\min }}/$((°)·s−1) 0 最大艏摇角速度${r_{\max }}/$((°)·s−1) 30(−30) 艏摇角加速度$\dot r/$((°)·s−1) 5 表 6 算法参数设置
Table 6. Parameter settings of algorithm
参数 数值 最小安全距离${D_{\min }}/m$ 2.0 障碍物外包圆直径$R/\rm m$ 1.5 采样时间间隔${d_{\rm t}}/s$ 1.0 前进速度离散间隔$ {d_u}/ $(m·s−1) 0.1 艏摇角速度离散间隔${d_r}/$((°)·s−1) 1.0 预测轨迹采样间隔数$T/\rm s$ 7.0 表 7 密集度函数参数设置
Table 7. Parameter setting of density function
参数 数值 $\delta $ 0.30 $\varepsilon $ 0.25 $\mu $ 0.50 $a$ 1/50 $b$ 1/2 表 8 无人艇及感知窗口初始状态设置
Table 8. Initial state setting of USV and sensing window
参数 数值 起始坐标 (0,0) 目标坐标 (90,90) 感知窗口角度/(°) 100 感知窗口半径/m 13 起始艏向$\vartheta $/(°) π/4 起始前进速度$u/$(m·s−1) 0 起始艏摇角速度$r/$((°)·s−1) 0 表 9 实验数据
Table 9. Experimental data
权值参数 安全距离/m 迭代次数/次 轨迹长度/m 运行时间/s α=2,β=15,γ=1 3.56 109 127.30 14.445 α=2,β=1,γ=15 3.34 86 125.10 10.768 α=2,β=βd,γ=γd 4.09 85 124.10 10.071 -
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