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3D obstacle avoidance method and simulation for unmanned helicopter
MENG Zhijun , PING Xueshou , CHEN Xuzhi
School of Aeronautic Science and Engineering, Beijing University of Aeronautics and Astronautics, Beijing 100083, China
Received: 2015-07-28; Accepted: 2015-09-18; Published online: 2015-11-19 10:19
Corresponding author. MENG Zhijun.Tel.:010-82317557.E-mail:mengzhijun@buaa.edu.cn
Abstract: Autonomous obstacle avoidance is an indispensable ability for unmanned helicopter (UH) operating low-altitude flight. A new 3D real-time avoidance method was presented to solve UH obstacle avoidance problem in complicated environment. The vision space of sensor was divided into several unequal radii sector-shaped cylinders and cuboids distributed at the same angle, estimating the obstacle distribution based on sensor data, and UH can execute corresponding maneuver calculated by this method to avoid obstacles successfully. An originally 3D simulation method was also proposed using secondary development technology on CATIA, which can build 3D model for undiscovered environment. Combined with the obstacle avoidance method, real UH obstacle avoidance flight simulation was carried out in it. The feasibility of 3D obstacle avoidance method was validated using the proposed simulation method.
Key words: unmanned helicopter     3D obstacle avoidance     3D simulation     obstacle avoidance simulation     CATIA secondary development

1 避障模型与方法 1.1 避障模型

1.1.1 虚拟平台简介

1.1.2 探测区域划分

 图 1 二维探测区域扇区划分 Fig. 1 Sector division of 2D detection zone

 图 2 三维探测区域扇区划分 Fig. 2 Sector division of 3D detection zone
1.2 避障方法

1.2.1 二维避障

 图 3 二维避障流程图 Fig. 3 Flowchart of 2D obstacle avoidance

 β1，β2—轴线与障碍物两侧边沿的角度；γ0—轴线与目标夹角；γ1，γ2—理想航向与障碍物两侧边沿的角度；α—β2的余角。 图 4 状态2避障示意图 Fig. 4 Schematic diagram of obstacle avoidance for state 2

C区有障碍物(状态4)，则判断FM以及N扇区内其他直方区的障碍物分布情况，使直升机航向往最靠近目标方向的无障碍物的直方区方向靠近，若FMN扇区所有直方区均有障碍物则说明进入死胡同，直升机顺时针调整航向。

1.2.2 三维避障

 图 5 三维避障流程图 Fig. 5 Flowchart of 3D obstacle avoidance

 (1)

 (2)

 图 6 障碍物高度探测 Fig. 6 Obstacle height detection

1.3 方法优化

1.3.1 避障飞行速度控制

 (3)

 状态区间 vmax-d/ (m·s-1) dmin/m 状态1 2.0 30.0 状态2 1.5 15.0 状态3 1.0 5.0 状态4 0 2.5

 S/m S>30 20

1.3.2 转弯优化

 v/(m·s-1) v<0.5 0.51.5 rmax/((°)·s-1) 90 30 20 10

1.3.3 U型障碍物规避优化

 图 7 U型障碍物规避优化前后 Fig. 7 Obstacle avoidance without and with U-shaped optimization
2 三维避障仿真

2.1 三维仿真平台

 图 8 仿真窗口 Fig. 8 Simulation windows

2.1.1 避障环境三维建模

2.1.2 传感器扫描模拟

 (4)
 图 9 激光探测模拟 Fig. 9 Laser detection simulation
 图 10 切割扫描线获取障碍物点坐标 Fig. 10 Obtain coordinates of obstacle via splitting scanning lines

2.2 仿真验证

2.2.1 速度控制及转弯优化仿真

 图 11 增加速度控制及转弯优化前后仿真效果图 Fig. 11 Simulation before and after speed control and turning optimization

2.2.2 二维复杂环境避障仿真

 图 12 二维避障仿真 Fig. 12 Simulation of 2D obstacle avoidance

2.2.3 三维综合避障仿真

 图 13 3D复杂环境避障仿真 Fig. 13 3D obstacle avoidance simulation in complicated environment
 图 14 避障仿真俯视图 Fig. 14 Vertical view of obstacle avoidance simulation
 图 15 前飞速度对比 Fig. 15 Forward speed contrast
 图 16 飞行轨迹高度对比 Fig. 16 Height contrast of flight trajectory

3 结 论

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#### 文章信息

MENG Zhijun, PING Xueshou, CHEN Xuzhi

3D obstacle avoidance method and simulation for unmanned helicopter

Journal of Beijing University of Aeronautics and Astronsutics, 2016, 42(8): 1619-1626
http://dx.doi.org/10.13700/j.bh.1001-5965.2015.0499