Visual Trajectory Tracking by Preview Control

The key for performing a robotic task in an uncertain environment is a control in the object-centered coordinate system. The visual servoing has been studied as an object-centered control method, however, it is unsuitable for tracking a trajectory because it is a PTP control. In this paper, a novel trajectory tracking control method using visual information is presented. We apply the preview control so that a manipulator can track a trajectory described in the object-centered coordinate system. In the preview control, the criterion to be minimized is the integral of the summation of square tracking error and kinetic energy. The optimal control law in the discrete time system is also proposed. Since this method refers to the future information, it can reduce a tracking error and suppress the amplitude of the velocity. Experimental results show that exact and smooth tracking is realized.