Research On Control System Of Semi-Strapdown Photoelectricity Stabilized Platform

Semi-strapdown stabilization method using the information of missile IMU toachieve the optical axis inertial stability, effectively solve the large bulk, heavy weightand high cost issues that existed in traditional gyro platform, and becomes the focus ofseeker technology development. This thesis has a central research on the principleprototype of semi-strapdown photo-electricity stabilized platform, includingkinematics, stable principle, dynamics, friction compensation, system overall stability,matched filtering, velocity measured, control algorithm and LOS rate.First, based on the theory of spatial mechanisms, according to the structure of thesemi-strapdown photo-electricity stabilized platform, the spatial coordinatetransformation is used to compute the command angle for stabilization. The stabilityequation of optical axis in the inertial space is established. Compared with theprinciple of direct and semi-strapdown stability, several kinds of control and gyroconfiguration are showed and the advantages and disadvantages are pointed out.Based on the analysis of kinematics, the principle of Newtonian mechanics and theEuler dynamic equations of a rigid body rotation are used to build the dynamicequation of semi-strapdown photo-electricity stabilized platform. Based on theprinciple prototype of semi-strapdown photo-electricity stabilized platform, theangular velocity and acceleration and the coupling torque between the framework areanalyzed by numerical simulation, basis for the development and design of controlsystem.Furthermore, in order to improve the stability and tracking performance, theresearch including friction compensation, matched filtering, velocity measured andcontrol algorithm design is carried out. The friction compensation is based on thekulun-viscous friction model and the controller design is based on pole assignment.The disturbance observer is proposed to solve the problem of the friction model inactual engineering; the matched filtering is designed for the velocity measurement and gyro dynamical matching problem, the decoupling precision of missile disturbance isimproved; the tracking differentiator is used to measure the velocity of the framework;the lead-lag compensator is used in velocity stable loop, the isolation of yaw and pitchframework is5.97%and5.42%when the missile disturbance amplitude is1degreeand frequency is2Hz; the fuzzy PID controller is used in position track loop, thetracking precision of yaw and pitch is2.42mrad and2.05mrad when the trackingspeed is3°/s.Last, the research of LOS rate of semi-strapdown photo-electricity stabilizedplatform is carried out. The LOS coordinate of semi-strapdown photo-electricitystabilized platform is established using LOS error angle. The LOS model under theLOS coordinate is raised using multi-coordinate transformation. Error propagationand synthesis principle is used to analyze the LOS rate accuracy including gyromeasurement error, encoder measurement error and machinery installation error. TheLOS rate of the principle prototype of semi-strapdown photo-electricity stabilizedplatform is analyzed, which is0.88mrad/s,3.8mrad/s and3.2mrad/s for three aspects,providing a theoretical basis for mechanical design and the choice of measurementdevice of semi-strapdown photo-electricity stabilized platform.