Robust stabilization of second-order image-based affine systems

Abstract In this paper, the problem of robust relative positioning between a 6-DOF robot camera and an object of interest is considered. Assuming weak perspective camera model and local linear approximation of visible object's surface, an image-based state space representation of robot camera–object interaction model is derived, based on the matrix of 2-D affine transformations. Dynamic extension of the visual model permits to estimate 3-D parameters directly as functions of state variables. The proposed nonlinear robust control law ensures asymptotic stability but at image singularities, assuming exact model and state measurements. In the presence of bounded uncertainties, under appropriate choice of control gains, ultimate boundedness of the state error is also formally proved. Simulation results validate the theoretical framework both in terms of system convergence and control robustness.