LaLo-Check: A Path Optimization Framework for Sampling-Based Motion Planning With Tree Structure

Motion planning is a basic problem in many areas, such as robotics, computer games, and animation. It is a challenge to generate a better solution in less time. Line-of-Sight (LoS) is the straight path between two points, and LoS-Check is often used as a path shortcutting method. Lazy evaluation is a successful strategy in reducing the amount of collision detection, which accelerates the motion planning algorithms, especially in high-dimensional spaces. In this paper, we present Lazy LoS-Check (LaLo-Check), which employs a lazy evaluation strategy with the help of a lower bound technique to delay the LoS-Check until it is necessary. The lower bound technique only accepts the states which could provide a better solution, and it is commonly applied in the sample rejection and candidate path selection. Actually, LaLo-Check can be considered as a general path optimization framework, which could be used in most tree-structure motion planners. We choose three representative sampling-based motion planning algorithms, RRT*, Informed RRT*, and BIT*, to evaluate the performance of LaLo-Check. The experimental results show that the new planners which employ the LaLo-Check could find better solutions than the original algorithms within the equivalent time.