Construction of observer-based visual servo controller

This paper describes a novel approach for a robust motion control based on image signal. The considered system has a 3-link planer redundant manipulator and a CCD camera mounted on its end-effector. In case the motion command of a manipulator is calculated from several feature points obtained by image signal, the kinematic transformation among coordinates is required. In the practical application, however, the image signal includes several kinds of errors caused by the unknown modeling error. In general, it is assumed that these errors are negligible amount. In the precise motion control based on the vision sensor, the above assumption is not always acceptable. To suppress the disturbance effect of the modeling error in the vision based motion system, the paper introduces the image space observer. The proposed controller has a simple structure and is applicable to the vision based system without increasing the calculation effort. The validity of the image space observer is confirmed by several numerical and experimental results in a 3-link planer manipulator system.