Fuzzy sliding mode control for pan-tilt-zoom system driven by ultrasonic motor

It is difficult for the traditional pan-tilt-zoom (PTZ) system driven by electromagnetic motor to meet the growing demand for video surveillance system. The key bottleneck problem is high positioning accuracy, high dynamic performance and miniaturization of the PTZ system. This paper presents a PTZ system driven by two degree-of-freedom obelisk-shaped ultrasonic motor with single stator, and makes research on its intelligent control algorithm. First, analyses of the structure, driving mechanism and electromechanical coupling system characteristic of the PTZ system are conducted using both the method of simulation and experiment. Then for the sake of solving the complex nonlinear factors, parameter variation and external disturbance, this paper combines the fuzzy logic algorithm and the sliding mode control strategy to improve the control performance. The results of simulation show that this algorithm proposed in this paper has faster response, higher precision and also has a good robustness to prevent the effect of interference.