Research On High Accuracy Attitude Determination Methods For On-Orbit Satellite Based On Multiple Sensors

With the development of astronautical technology,the task for satellite is required more highly.To perform these tasks well,we need to upgrade the accuracy of the attitude determination system.The attitude determination system of sateliite mainly includes the sensors and attitude determination algorithms,and high-accuracy attitude determination usually choose star tracker and gyroscope as the main attitude sensor.Due to the volatility in the process of launch and the environmental factors in the period of orbit operation,many parameters of star tracker and gyroscope are different from the parameters that were calibrated on the ground,this case has a great influence on the accuracy of on-orbit determination system.Thus,we should take more attention to the calibration of attitude sensors.In addition,there are various attitude determination algorithms in the determination system.Therefore,the selection of these algorithms will affect the accuracy of attitude determination system.Based on the subject of two star trackers and gyroscope,this paper calibrates the main parameters of attitude sensor model to prohibit the dispersal of attitude error in the attitude determination system.At the same time,the attitude determination algorithm is also used to improve the accuracy of attitude determination.Besides a preliminary analysis is made on the usability of star tracker to avoid the influence of stray light.Firstly,this paper introduce the main frame,default parameters and attitude description that are used in the case of attitude determination and building attitude sensor models.Then the system's attitude sensors are established and the main errors that exist in the sensor models are explained.Secondly,the optical error of star tracker are calibrated,star tracker is a very high accuracy attitude sensor,whose accuracy has a great effect on the accuracy of attitude determination system.Then the causes of the main parameters in the model of star sensor are explained.Aiming at the major parameters of this model,calibration is conduted on the invariant principle of star diagonal distance,and simulation vertification is carried out.The error of constant drift,installation error and calibration factor of gyroscope model are calibrated.As the sensor of continuous angular velocity,the gyroscope also has a great influence on the accuracy of attitude determination system.Based on the method of the least square and filtering,the gyroscope's parameters are calibrated and the algorithm is verified with stimulations.Furthermore,the algorithm of star tracker/gyroscope attitude determination is studied.The EKF and UKF algorithm,as the method of state estimation,are introduced in detail,and the design of the attitude determination process is also carried out.The precision of two algorithms and calculation are analyzed by multiple sets of numerical stimulation.Finally,two star trackers and gyroscope are established as the subject of the combination system,and the algorithm of binary-sensor and gyroscope is studied,which is based on a kind of federated kalman filter.Basing on the environmental factors of star sensor,a principle of the star sensor's usability is established.And considering the above-mentioned factors,the overall process is designed for the system,which establishes the relationship among these parts.Then the way is verified by using the actual satellite example of large-angle maneuver.