A new simple visual control method based on cross ratio invariance

A new visual control method for the end-effector of a robot to approach an object is proposed in this paper, which consists of tracking, approaching and decision part. Two uncalibrated cameras are employed. One is for track the object in its image space. Another is for approach the object in the direction of affine line between first camera and the object. The distances between the current and desired positions of the end-effector are estimated according to the end-effector´s actual movements based on cross ratio invariance. The approaching part is enabled or disenabled by the decision part according to the result of tracking part. With the combination of tracking and approaching, the end-effector is moved to the target object. Experimental results are presented to verify the effectiveness of the proposed method.