Research On The Control System Of Gyro Stabilized Pod

With the development of the modern warfare, a broad array of high-precisionand long-distance technologies of information investigation, target positioning andtracking, precision guided weapon based on air force have proved their prominencein informationized warfare. Optical stabilized tracking platforms can provide aneffective solution for the problem of the photodetector disturbance caused by theaircraft’s variation. By helping the line of sight of the photodetector remain stable inthe inertial space, an optical platform allow the photodetector to acquirehigh-accuracied images, and keep tracking the target accurately, thus attracts greatattentions. The main goal of this research is designing a feasible control system of agyro stabilized pod.By studying the development and research productions of gyro stabilizedplatform at both home and abroad, the main study directions and key difficultieshave been summarized, which provides a directional guidance for this dissertation.After the analysis of the main factors of gyro stabilized pod performance, thediscussion of LOS stabilization methods and the pod servo structures, the differenceof disturbance rejection ability between two-gimbal and four-gimbal structures oftwo-axis pods has been further discussed. Based on the above-mentioned analysis,the pod performance requirements are given, as well as the overall design, selectionof the main components, and the mathematical model of the pod control system.Based on the analysis of the control structure disturbance rejection performance,a four-looped control structure including posision loop, stable loop, speed loop, andcurrent loop is brought up. According to the requirements of pod performance,torque stiffness and isolation, a frequency-domain-based PID corrector has beendesigned, and meet the demands of the design target as the result of simulationbased on ideal model shows. In order to overcome the deficiency of the PID controlmethod on the disturbance rejecting and low-speed stability, an upper-limit-basedsliding model controler is applied for the stable loop. The simulation result indicatesthat, under the combined effect of both non-linear friction and disturbing angularvelocity, the sliding model controler provides a better performance on low-speedstability and disturbance rejecting than the PID corrector does. Besides, to relievethe chattering phenomenon, a saturation function based on quasi-sliding mode isused to rebuild the controller. By the simulation result, this method is proved to beeffective in chattering inhibition and able to keep the control performancesatisfactory at the same time. Further more, to solve the delay problem of TV tracker,combining the method of target position composition, a normalized LMS adaptive predictor is designed for delay compensation, and acquires a good simulation result.