Fast path planning using modified A* method

An algorithm is presented for planning the path of an object (robot) through an obstacle cluttered space by using a modified A* method for searching through the free space. The A* method can be extremely slow for large numbers of cells to be searched. The alternative presented is to use trial vectors that span several cells to aid in the planning. The fine resolution of the obstacle mapping is maintained. A loose search is performed on the fine grid. The paths that are found using this method are slightly sub-optimal. The speed of the searching algorithm is significantly increased. Solution times for three-dimensional problems are typically below 100 milliseconds, while the traditional A* search for the same problem is several minutes. The trade-off is a large speed increase for a slight degradation in path length optimality. Two-dimensional problems are solved very quickly