The Delayed D* Algorithm for Efficient Path Replanning

Mobile robots are often required to navigate environments for which prior maps are incomplete or inaccurate. In such cases, initial paths generated for the robots may need to be amended as new information is received that is in conflict with the original maps. The most widely used algorithm for performing this path replanning is Focussed Dynamic A* (D*), which is a generalization of A* for dynamic environments. D* has been shown to be up to two orders of magnitude faster than planning from scratch. In this paper, we present a new replanning algorithm that generates equivalent paths to D* while requiring about half its computation time. Like D*, our algorithm incrementally repairs previous paths and focusses these repairs towards the current robot position. However, it performs these repairs in a novel way that leads to improved efficiency.