A novel pan-tilt camera control approach for visual tracking

In this paper, we propose a novel pan-tilt control approach for visual tracking. The approach uses the target image feature to control the pan-tilt device following the target with random movement. In order to improve the performance of pan-tilt camera platform, active disturbance rejection control (ADRC) technique is applied to the tracking control of pantilt camera. The approach uses two ADRC controllers working in parallel for a pan-tilt camera platform which can be fixed on an autonomous mobile robot. This kind of control scheme does not need the precise mathematical model of pan-tilt camera tracking system and also not need the movement state of the target. In ADRC technique, many uncertain factors, estimated and compensated by extended state observer (ESO), are treated as system disturbance in real time. Then, the original nonlinear control system is reduced to a cascade integral form, which is easy to design 1-order ADRC controllers for the system. The tracking system uses a basic mean shift tracker, which calculates the error between the target image position and the center of the image in each frame for the controllers. Experimental results on a mobile robot show that the pan-tilt camera can track the moving target efficiently and stable.