Fractional control of stabilized platform for photoelectric gyro

To improve the isolation of a photoelectric gyro stabilized platform and to improve its accuracy of stability and tracking within velocity disturbance, the fractional PI controller was applied to the rate loop control of the photoelectric gyro stabilized platform. First, the shortcomings to improve system accuracy by the conventional PI control were mentioned. Then, the fractional calculus and fractional order PID control were introduced and the fractional PI controller was proposed to improve the control accuracy of the control system. According to the equivalent first-order integral model with a current loop, the design method of fractional PI controller parameters also suitable for the integer-order PI controller was proposed based on phase margin and crossover frequency. Finally, a fractional PI controller and an integer order PI controller were respectively used to perform the experiments on step response, the residues of velocity disturbance and stable accuracy for an airborne photoelectric gyro stabilized platform. Experimental results show that the system with fractional PI controller has smaller overshoot than that with PI controller. The isolation of velocity disturbance is improved about 38% and the stability is improved about 40% at a frequency of 0.5 Hz and an amplitude of 3.14 ()/s. The experiments demonstrate that control accuracy of system can be improved by using fractional PI controller under ensuring the stability margin.The method proposed can be easily realized on engineering.