Essential-matrix-based visual servoing of nonholonomic mobile robots without short baseline degeneration

For a nonholonomic mobile robot system equipped with a fixed camera, we propose a novel essential matrix-based switching visual servoing strategy in this paper by using multiple essential matrices to address the short baseline degeneration problem. Firstly, three essential matrices of the system are introduced, which are then estimated up to a determinable constant scale factor with respect to their true value by the assistance of two co-vertical line feature points. To deal with the short baseline degeneration problem of essential matrices and the nonholonomic motion constraint, a three-stage switching control law, which is free of any complex pose estimation algorithm, is subsequently designed by selecting proper essential matrices, despite the lack of metric information of the scene. The rapid convergent property of system errors is proven with mathematical analysis. The performance of the proposed strategy is validated through simulation results, which demonstrate that this strategy achieves efficient regulation for a nonholonomic mobile robot by successfully solving the short baseline degeneration problem.