On The Fractional Order Control Of Airborne Photoelectric Stabilized Platform

Airborne photoelectric stabilized platform, as an important part of the airbornephotoelectric reconnaissance mission equipment, has a wide range of applications inthe enemy situation reconnaissance, target location, precision attack and so on. Itschief responsibility is to ensure the stability of optical axis by measuring andovercoming the attitude changes of carrier aircraft, the vibration of the engine, theairflow changes as well as itself frictional torque, wire disturbance torque, massimbalance torque, sensor noise disturbance and so on. In addition to the optical designand mechanical structure of the airborne photoelectric stabilized platform, the controltechnology is one of the key technologies of the photoelectric reconnaissancemissions to improve the location accuracy and capability of precision attack.This thesis took a more in-depth study of the photoelectric gyro stabilizedplatform control technology in order to improve the control performance andprecision, base on the mathematical modeling, theoretical analysis and experimentalvalidation. The full text of the main content and the results are as follows:①The thesis established the fractional order mathematical model of airbornephotoelectric stabilized platform after analyzing the linear and nonlinearcharacteristics. The modeling process includes three aspects: the current loop designand modeling, sensors and mechanical resonance modeling and nonlinearcharacteristics modeling. The thesis introduced the design and modeling of currentloop in detail. Two practical modeling method of current loop was proposed. Itfocused on the Allan variance modeling of inertia sensor gyro, considering thequantization error, random walk angle, angular rate random walk and bias stability. Then, the thesis established the friction nonlinear model, the mass imbalance modeland the wire disturbance torque model of the system. It pointed out the traditionalmathematic model that is composed with linear and nonlinear characteristics is verycomplex and can not describe the actual system. The fractional order model ofairborne photoelectric stabilized platform was established by using frequencyidentification method. The model can describe the actual system in compact form.②A universal fractional order PIλcontroller design method wad proposed basedon stability margin and cutting frequency. It can solve the problem of stableperformance variation cause of increasing the open-loop gain integral part to improvecontrol accuracy in the past. Simulation and experimental study had been taken byusing fractional order PIλcontroller an integer order PI controller on a certainairborne photoelectric stabilized platform. The comparative experiments of stepresponse, velocity perturbation isolation, torque disturbance isolation and stableprecision showed that: the control system with fractional order PIλcontroller had asmall overshoot, the isolation of velocity perturbation increased approximately38%and stable accuracy is improved by about40%on the condition of sinusoidal velocityperturbation with amplitude of3.14o/s and frequency of0.5Hz.③A simplified pseudo-differential feedback control (PDF) strategy and fractionalorder pseudo-differential feedback control (FOPDF) algorithm were proposed andapplied to the airborne photoelectric stabilized platform. A series of simulationcomparison experiments were carried out between PDF controller, FOPDF controllerand PI controller in the anti-torque disturbance, isolation of the angular ratedisturbance of the vehicle and the plant variation on the airborne photoelectricstabilized platform. The results showed that the servo system of airborne photoelectricstabilized platform with PDF controller and FOPDF controller was superior to thesystem with PI controller in the same closed-loop bandwidth. It has smaller overshootand shorter rise time and regulating time. It is better than PI on the suppression oftorque and the airborne attitude disturbances within gyro noise. The system withFOPDF controller is more robust than that with PDF controller on the condition ofmodel variation.The work of this thesis for fractional order control system, fractional order PIDcontrol, pseudo-differential feedback control and fractional order pseudo-differentialfeedback control on the application of airborne photoelectric gyro stabilized platformprovides theoretical support and technical reference, also can be some reference to related areas.