Efficient Robot Motion Planning Using Bidirectional-Unidirectional RRT Extend Function

In this article, based on the rapidly-exploring random tree (RRT), we propose a novel and efficient motion planning algorithm using bidirectional RRT search. First, a RRT extend function is used to organize the sampled states under kinodynamic constraints. Meanwhile, the bidirectional search strategy is implemented to grow a forward tree and backward tree simultaneously in the tree extension process. When these two trees meet each other, the backward tree will act as a heuristic to guide the forward tree to continuously grow toward the goal state, where the algorithm switches to unidirectional search mode. Therefore, the two-point boundary value problem (BVP) in the connection process is avoided, and the extension process gets much accelerated. We also prove that probabilistic completeness is guaranteed. Numerical simulations are conducted to demonstrate that the proposed algorithm performs much better than the state-of-the-art algorithms in different environments.
Note to Practitioners
—The motivation of this work is to develop an efficient sampling-based motion planning algorithm for mobile robots. Conventional sampling-based algorithms are time-consuming to find a feasible solution under differential constraints. When applying bidirectional search strategy to improve them, the complex 2-point BVP is required to solve. In this article, the backward free is regarded as a heuristic to guide the tree growth. On the one hand, the advantage of bidirectional search is retained. On the other hand, the 2-point BVP is avoided. Therefore, the bidirectional-unidirectional technique can achieve efficient robot motion planning. The proposed algorithm can be extended to other specified sampling-based algorithms to further improve their performance. Besides, it can be also applied to autonomous driving, service robot and medical robots to achieve efficient motion planning.