Abstract: In order to solve the global path planning problem of fire robot in complex closed environment， a synchronous bidirectional A* algorithm based on improved heuristic function is proposed. Firstly， the traditional one-way search of A* is changed to synchronous two-way search， and the forward and reverse search target nodes are dynamically defined. Secondly， a “normalization” factor function is added to the evaluation function to prevent the disjoint of forward and reverse search paths， and a dynamic weight function is added to the estimated cost function to reduce the generation of redundant nodes in the search process. In order to solve the problem of many inflection points and unsmooth search path， a solution of corner optimization and local smoothing based on Bezier curve is proposed. Finally， through simulation comparison and real environment experiments， the advantages of the improved algorithm in path length， search time， number of traversing nodes and inflection points are proved， and the effectiveness of the algorithm is verified.

Key words: firefighting robot, path planning, synchronous bidirectional A* algorithm, corner optimization, path smoothing