Motion planning for a tethered mobile robot

Abstract

Recently there has been surge of research in motion planning for tethered robots. In this problem a planar robot is connected to a base via a flexible cable assumed to be always stretched of limited length L. The existence of the cable causes additional constraints on the motion of the robot. Our method consists of finding a shortest path for a robot having an initial cable layout from a given position to the goal. The shortcut algorithm is used to estimate the cable configuration by smoothing and refining the path constituted of the concatenation of the initial cable layout and the path candidate without violating the homotopy class. This heuristic determines whether a target position can be reached for a given tether configuration. The algorithm was evaluated and validated on Matlab by planning trajectories in an environment with obstacles of different shapes, and by setting different cable lengths. The results of our path planning approach have shown that the obtained smoothed path between base and goal position matches exactly the cable’s configuration. In addition, homotopy classes are preserved when performing the smoothing operation over the path.