We present a method for defining a hybrid control system capable of simultaneously addressing the global navigation and control problem for a convex-bodied wheeled mobile robot navigating amongst obstacles. The method uses parameterized continuous local feedback control policies that ensure safe operation over local regions of the free configuration space; each local policy is designed to respect nonholonomic constraints, bounds on velocities (inputs), and obstacles in the environment. The hybrid control system makes use of a collection of these local control policies in concert with discrete planning tools in order to plan, and replan in the face of changing conditions, while preserving the safety and convergence guarantees of the underlying control policies. In this paper, we provide details of the system models and policy definitions used to validate the approach in simulation and experiment with a convex-bodied wheeled mobile robot. This work is one of the first that combines formal planning with continuous feedback control guarantees for systems subject to nonholonomic constraints, input bounds, and non-trivial body shape.

Abstract — We present the local path planning and obstacle avoidance method used on the autonomous tour-guide robot RoboX. It has proven its value during a 5 month operation of ten such robots in a real-world application, a very crowded exhibition. Three known approaches (DWA, elastic band, NF1) have been integrated into a system that performs smooth motion efficiently, in the sense of computational effort as well as goal-directedness. Apart from modifications to the DWA and the elastic band, we present the formulations that allow this fusion. I.

ingénieur en microtechnique diplômé EPF et de nationalité allemande acceptée sur proposition du jury: Prof. R. Siegwart, directeur de thèse