ERA*: Enhanced Relaxed A* algorithm for solving the shortest path problem in regular grid maps.

This paper introduces a novel algorithm for solving the point-to-point shortest path problem in a static regular 8-neighbor connectivity (G8) grid. This algorithm can be seen as a generalization of Hadlock algorithm to G8 grids, and is shown to be theoretically equivalent to the relaxed A ⁎ (R A ⁎) algorithm in terms of the provided solution's path length, but with substantial time and memory savings, due to a completely different computation strategy, based on defining a set of lookup matrices. Through an experimental study on grid maps of various types and sizes (1290 runs on 43 maps), it is proven to be 2.25 times faster than R A ⁎ and 17 times faster than the original A ⁎ , in average. Moreover, it is more memory-efficient, since it does not need to store a G score matrix. [ABSTRACT FROM AUTHOR]