A* algorithm used in three-dimensional environment for optimal path planning

In this paper, we obtain three-dimensional topographic height information by sensors and use gradient threshold method to deal with flatness on ground. Thus, there should be three robot traffic conditions: passable area, access more difficult area and hazard area. Then according to the robot´s parameters, appropriate threshold value for traffic conditions will be obtained and then is stored in two-dimensional array in corresponding coordinates of the processed image. So we can establish an appropriate database table structure, and relational tables are built to connect the grid node information, road information and road access hardness information. Whereafter, we take advantage of A * algorithm to search for driving area and add threshold value as search path cost, so it´s not only the shortest possible path, but also more efficient access path. It is proved that this can make better results, because it takes into account the corresponding actual geographical environment.