Optical Flow Based Mobile Robot Obstacle Avoidance Method in Unstructured Environment
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摘要: 为了解决在复杂非结构化环境中的避障问题,提出了一种基于光流的适用复杂非结构化环境的移动机器人避障方法. 首先,引入梯度守恒假设和局部加权对光流算法进行改进,减少了光照变化不均和噪声对光流算法的影响,提高了算法的计算精度和鲁棒性. 然后,使用光流散度来计算相碰撞时间(time-to-contact,TTC),并利用TTC构建障碍地图. 设计的航向决策算法能在机器人与障碍物发生碰撞危险时,为机器人选择最优的前进方向. 对提出的避障方法进行了仿真及物理实验,实验结果表明:利用该避障方法可以实现移动机器人在复杂非结构化环境中无碰撞地行走.Abstract: In order to solve the obstacle avoidance problem in complex unstructured environment, inspired by the optical flow navigation strategies of insects, an algorithm of visual obstacle avoidance for autonomous mobile robot was developed in this paper, which is suitable for complex unstructured environment. In order to reduce the influence of illumination changes and noise, improve the calculation accuracy and robustness of the optical flow algorithm, the gradient constancy assumption was introduced and the local was weighted. And the flow divergence was used to calculate the relative depth time-to-contact (TTC). Then an obstacle map was constructed based on the TTC. When robots were at risk of collision with the obstacles, the heading direction decision algorithm was designed for robot to choose the optimal direction. Simulation and physical experiments were done in this paper. Experimental results show that the presented method can guarantee a mobile robot wander without collision in unknown complex unstructured environments.
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Key words:
- mobile robot obstacle avoidance /
- optical flow /
- time to contact /
- obstacle map
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图 9 把图像分成N=20列时构建的障碍地图
Figure 9. Obstacle map constructed when divide the image into N=20 columns
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