Visual Servoing of a Redundant Manipulator Using Shape Moments

This paper is concerned with real-time visual servoing of a redundant ma-nipulator using shape moments. The forward kinematics of the PowerCube manipulatorwith seven degrees of freedom (DOF) has been derived. The visual servoing is carriedout with camera placed at the end-effector which is also known as eye-in-hand config-uration. Image plane features such as centroid, area and orientation are considered toderive the image interaction matrix (image Jacobian) that maps image plane pixel veloc-ities to the end-effector Cartesian velocities. The proposed image based visual servoing(IBVS) method uses the moments invariant of an elliptical object and can position theend-effector to grasp the object with z-axis orientation of the end of effector. Actualexperiments have been carried out on the PowerCube manipulator from Amtec Roboticsto show that kinematic and image Jacobians derived are accurate.