A path following controller for wheeled robots which allows to avoid obstacles during transition phase

Classically, closed-loop path-following controller are used to perform the displacement of mobile robots along pre-planned paths. However, when the initial configuration of the robot is far from the reference path, the stabilization process may involve an important transition phase before the robot moves along the path. Though it is possible to guarantee that the robot will not collide with obstacles as it moves closely along the path, it is hard to insure the motion to be safe during the transition phase. The paper presents a path following controller for mobile robots, allowing it to avoid obstacles during the transition phase. The control design is based on sliding mode techniques. We define a time-varying sliding manifold and we use this degree of freedom to modify the shape of the robot´s trajectory, during the path-following process. Our technique is applied to the model of a unicycle, making the simplifying hypothesis that the obstacles encountered are strictly convex