Résumé
This paper proposes an algorithm that drives a unicycle type robot to a desired path, including obstacle avoidance capabilities. The path following control design relies on Lyapunov theory, backstepping technics and deals explicitly with vehicle dynamics. Furthermore, it overcomes initial condition constraint present in a number of path following control strategies described in the literature. This is done by controlling explicitly the rate of progression of a "virtual target" to be tracked along the path; thus bypassing the problems that arise when the position of the path target point is simply defined as the closest point on the path. The obstacle avoidance part is using the Deformable Virtual Zone principle, that defines a safety zone around the vehicle, in which the presence of an obstacle induces an "intrusion of information" that drives the vehicle reaction. The overall algorithm is combined with a guidance solution that embeds the path following requirements in a desired intrusion information function, that steers the vehicle to the desired path while the DVZ is virtually keeping a minimal contact with the obstacle, implicitly bypassing it. Simulation and experimental results illustrate the performance of the control system proposed.