S*: On Safe and Time Efficient Robot Motion Planning

Abstract

As robots and humans increasingly share the same workspace, the development of safe motion plans becomes paramount. For real-world applications, nonetheless, it is critical that safety solutions are achieved without compromising performance. The computation of safe, time-efficient trajectories, however, usually requires rather complex often decoupled planning and optimization methods which degrades the nominal performance. In this work, instead, we cast the problem as a graph search-based scheme that enables us to solve the problem efficiently. The graph search is guided by an informed cost balance criterion. In this context we present the S* algorithm which minimizes the total planning time by equilibrising shortest time-efficient paths and paths with higher safe velocities. The approach is compatible with standards and validated both in rigorous simulation trials on a 6 DoF UR5 robot as well as real world experiments on a Franka Emika 7 DoF research robot.