Non-Linear PID Control for Robotic Manipulator Visual Servoing

This paper presents an experimental study on the use of visual servoing for robotic tracking and manipulation of targets moving on a plane. In this work, the image is acquired from the camera mounted on the end-effector of a 6 DOF industrial robot, so that the camera moves on a plane parallel to that of object motion. Using a PID visual controller to minimize the relative displacement between object and end-effector, it can be seen that performances in system response are affected by the absolute velocity of target in space. In order to improve these performances, a non-linear structure for the PID controller has been implemented. The idea is to modify the PID structure according to the estimated velocity of the target. Experiments show that the modified PID controller increase tracking performances for both slow or still targets and fast moving targets. Keywords—Visual servoing, PID Control, Target Tracking.