Speeding up heuristic computation in planning with Experience Graphs

Experience Graphs have been shown to accelerate motion planning using parts of previous paths in an A* framework. Experience Graphs work by computing a new heuristic for weighted A* search on top of the domain's original heuristic and the edges in an Experience Graph. The new heuristic biases the search toward relevant prior experience and uses the original heuristic for guidance otherwise. In previous work, Experience Graphs were always built on top of domain heuristics which were computed by dynamic programming (a lower dimensional version of the original planning problem). When the original heuristic is computed this way the Experience Graph heuristic can be computed very efficiently. However, there are many commonly used heuristics in planning that are not computed in this fashion, such as euclidean distance. While the Experience Graph heuristic can be computed using these heuristics, it is not efficient, and in many cases the heuristic computation takes much of the planning time. In this work, we present a more efficient way to use these heuristics for motion planning problems by making use of popular nearest neighbor algorithms. Experimentally, we show an average 8 times reduction in heuristic computation time, resulting in overall planning time being reduced by 66%. with no change in the expanded states or resulting path.