A construction of observer-based visual servo controller

This paper describes a novel approach for a robust motion control based on image signals. The considered system has a three-link planar 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, kinematic transformation among coordinates is required. In practical applications, however, the image signal includes several kinds of errors caused by unknown modeling error. In general, it is assumed that these errors are negligible. In precise motion control based on vision sensors, the above assumption is not always acceptable. To suppress the disturbance effect of the modeling error in vision-based motion systems, this paper introduces the image space observer. The proposed controller has a simple structure and is applicable to vision-based systems without increasing the calculation effort. The validity of the image space observer is confirmed by several numerical and experimental results in a three-link planar manipulator system