Nonholonomic, bounded curvature path planning in cluttered environments

The problem of planning a path for a robot vehicle amidst obstacles is considered. The kinematics of the vehicle considered are of the unicycle or car-like type, i.e. are subject to nonholonomic constraints. Moreover, the trajectories of the robot are supposed not to exceed a given bound on curvature, that incorporates physical limitations of the allowable minimum turning radius for the vehicle. The method presented attempts to extend the Reeds-Shepp shortest paths of bounded curvature in an absence of obstacles, to the case where obstacles are present in the workspace. The method does not require explicit construction of the configuration space, nor employs a preliminary phase of holonomic trajectory planning. Successful outcomes of the proposed technique are paths consisting of a simple composition of Reeds/Shepp paths that solves the problem. For a particular vehicle shape, the path provided by the method, if regular, is also the shortest feasible path. Applications to both unicycle and car-like (bicycle) mobile robots of general shape are described and their performance and practicality discussed.