Mobile Robot Path Following Control in 2D Using a 3D Guiding Vector Field: Singularity Elimination and Global Convergence
Résumé
In vector-field-based path following (VF-PF), a vector field is designed and utilized to guide a robot to follow a desired path. VF-PF algorithms have been shown to achieve high path-following precision under small control effort compared with many other path following algorithms. However, due to the existence of singular points where the vector field vanishes, the global convergence of VF-PF algorithms to the desired path cannot be guaranteed. Moreover, as it holds for most of the existing path following algorithms, VF-PF algorithms may fail to enable following a self-intersected desired path. In this paper, we propose a method to assist generic VF-PF algorithms in their global convergence. In particular, our method creates vector fields free of singular points in a higher-dimensional space containing the lower-dimensional desired path. Subsequently, the projection of our vector fields on the lower-dimensional space of the desired path can be exploited to guarantee the global convergence of the robot to the desired path, including those self-intersected. Finally, we show that our algorithm combines and fairly extends features from existing path following algorithms and a nonlinear trajectory tracking algorithm. The theoretical results have been validated by experiments and simulations.