Stable visual servoing of camera-in-hand robotic systems

In this paper, the control problem of camera-in-hand robotic systems is con sidered. In this approach, a camera is mounted on the robot, usually at the hand, which provides an image of objects located in the robot environment. The aim of this approach is to move the robot arm in such a way that the i mage of the objects attains the desired locations. We propose a simple imag e-based direct visual servo controller which requires knowledge of the obje cts' depths, but it does not need to use the inverse kinematics and the inv erse Jacobian matrix. By invoking the Lyapunov direct method, we show that the overall closed-loop system is stable and, under mild conditions on the Jacobian, local asymptotic stability is guaranteed. Experiments with a two degrees-of-freedom direct-drive manipulator are presented to illustrate the controller's performance.