Abstract: To improve the safety of lunar rover during autonomous detection, an improved path planning algorithm based on Probabilistic Roadmap (PRM) is proposed. The algorithm is based on the distance transform map to improve the sampling method of the PRM algorithm. By controlling the sampling point away from obstacles, the planned path is kept away from obstacles, avoiding dangerous situations of advancing close to obstacles, and improving the safety of lunar rover. To evaluate the safety of the path, two safety indicators, a safety alert factor and a minimum safety alert factor, are proposed. And the paths generated by A*, PRM and the improved PRM algorithm are evaluated for safety in the lunar surface simulation environment. The results show that the improved PRM, compared with A* algorithm, the safety alert coefficient and the minimum safety alert coefficient of the algorithm are increased by 2.20m and 1.00m respectively; compared to the PRM algorithm, the safety alert coefficient and the minimum safety alert coefficient are increased by 1.68m and 1.00m, respectively. The improved PRM algorithm is not only limited to the path planning of lunar rover, but can also be applied to exploration robots and selfdriving cars that require high path safety.

Key words: lunar rover, path planning, PRM, safety indicators