Research On Floating Optoelectronic Platform High Precision Attitude Measurement Technology

The near space floating optoelectronic detection platform based on high-altitude balloon is an ideal platform for astronomical observations, Earth’s environment observation, space target tracking and observation, and space range measurement, which has great scientific significance and military value, subject to increasingly national attention. To fulfil the performance of optoelectronic payload needs a stable floating platform attitude, and high-precision attitude measurement is a necessary condition for attitude stabilization and control of floating platform. Therefore, this paper will expand research around the precision attitude measurement techniques of floating photoelectric detection platform, based on the application background of space range measurement and near-Earth space target observation.First, this paper studies the overall technic of the attitude measurement and control system for floating optoelectronic platform. Considering the pointing mechanism dynamic characteristics requirement of the floating optoelectronic detection platform used for space range measurement and near-Earth space target observation, a relative independent structure of the floating gondola and tracking turntable is designed. On the one hand, the structure isolated the gondola attitude disturbance imposed on the tracking turntable; on the other hand, it separates the gondola’s attitude control and the turntable’s pointing control, while satisfying the dynamic performance requirements of the floating optoelectronic detection platform.This paper analyzes the motion characteristic of floating optoelectronic detection platform. The stratospheric atmosphere environment and the motion state of high-altitude balloon are studied. Based on the motion state of high-altitude balloon, a detailed analysis of floating gondola’s rotation and swing that may arise in flight is conducted. The motion equation of the gondola is established, and the variation of gondola’s attitude is determined through solving the equations of motion. Combined with kinetics coupling analysis, the attitude disturbances due to the pointing maneuver of payload is studied.This paper proposes an attitude measurement method for the floating platform based on Polaris sensor and tilt sensor. The selection of Polaris observation vector avoids star pattern recognition algorithm or servo tracking device in ordinary star sensor, which reduces the star sensor requirements. The direction of gravitational acceleration is measured by a two axis tilt sensor. Using the two observation vectors from Polaris sensor and tilt sensor, a high-precision measurement of the floating gondola is obtained through TRAID algorithm.This paper presents an attitude measurement algorithm that combined the measurements of fiber optic gyroscope, Polaris sensor and tilt sensor. The algorithm implements the complementary advantages of each sensor, makes up the shortcomings of low update rate and low short-term precision of Polaris sensor and tilt sensor, while avoids the attitude drift due to the attitude passing algorithm based on fiber optic gyroscope, synchronous outputs of the attitude and attitude rate are achieved in high precision and high update rate. Through the establishment of the state-space model of attitude error and fiber optic gyro drift, attitude error and fiber optic gyro drift is estimated in real-time using the Kalman filter.The mathematical simulation and experimental validation of the attitude estimation and transfer algorithm is completed. The presented algorithm is simulated through simulation data generated by Matlab software. Using actual fiber optic gyro, the attitude measurement algorithms is partially verified. The simulation and experimental results verify the feasibility of the proposed attitude estimation algorithm for floating gondola, and achieve good attitude estimation results.Finally, the attitude estimation error of the floating gondola attitude determination system is analyzed. The attitude error sources are determined, and the effect of each error sources is analyzed. The overall accuracy of the floating gondola attitude determination system is evaluated. The results show that the arc-seconds order of magnitude attitude estimation accuracy can achieve through a reasonable choice of the available attitude sensors.Contents of this paper have important reference significance and high application value for the establishment of near space floating photoelectric detection platform.