Vision tracking realization of a robotic follow spot system

In this paper, we described about the actor-tracking techniques of a robotic follow spot system. The robotic follow spot system contains Pan-Tilt actuator mechanism and infrared detectable camera. The infrared LED modules, as markers, are attached on the actor´s head. The system detects the marker by the camera and actuates the follow spot to locate the marker be the center of the image. In order to improve the tracking speed, we used a very simple image processing algorithm, binarization and CG (center of gravity) calculation. The actor´s relative location from the center of the image is regarded as error. Controlling the Pan-Tilt actuators, which move the follow spot and the camera, compensates the error. PD control and digital LPF (Low pass filter) algorithm is applied. The control command is transferred to the physical AC servomotors by CAN (Control area network) interface.