Adaptive hybrid visual servoing/force control in unknown environment

This paper describes an adaptive hybrid visual servoing/force controller to realize visual servoing while the manipulator exerts contact force on a surface. The proposed controller has a hybrid structure of visual servoing control and force control. Because it has an online estimator for the parameters of the camera-manipulator system and the one for the parameters of the unknown constraint surface, it only needs a priori knowledge on the manipulator kinematics and nothing any more. First, we propose an estimator for an image Jacobian matrix which describes the relation between image features and the tip position/orientation of the manipulator. Second, a method to estimate the normal vector of the unknown constraint surface is introduced. Then, an adaptive hybrid visual servoing/force controller is proposed. Finally, experimental results are shown to demonstrate the effectiveness of the proposed scheme.