14. Low Speed Stability of Tracking Turntable for the Unmanned Air Vehicle Landing

In the unmanned air vehicle (UAV) landing test, the rate fluctuation of tracking turntable appears in using the grounding active laser guidance system. To improve its stability, the reasons for tracking turntable rate fluctuation at low speed are analyzed. It is verified that the motor cogging torque fluctuation is the main reason at low speed by modeling and experiment. A disturbance observer based compensation control on the basis of the traditional double closed loop PID correction is proposed. Through analyzing the dynamic structure of tracking turntable, the compensation equation of disturbance torque described by the angular acceleration and torque current is derivated and then the torque disturbance observer structure is designed based on the equation. The comparative test shows that the rate fluctuation is 2.12 % after compensation when the speed is 1(°)/s, lower over 3 times than by only the traditional double closed loop PID correction. This method proposed can improve low speed stability of tracking Turntable for the UAV landing.