Positioning of a robot with respect to an object, tracking it and estimating its velocity by visual servoing

An application is described of the so-called visual servoing approach to robot positioning with respect to an object and to target tracking. After briefly discussing how the task function approach can be applied to tasks which include the use of visual features, the authors give a simplified control expression which explicitly takes into account the case of moving objects. Estimating the target velocity while performing the tracking control leads to a kind of adaptive control scheme. The authors then consider the specific case of a square target and derive all the components of the control scheme. They present some experimental results obtained at the video rate in an experimental system composed of a camera mounted on the end effector of a six-DOF robot.>