Research On The Key Technology Of Micro-satellite Geomagnetic Positioning System

With the widely application of modern aerospace industry,The development of orbit micro satellite with low power consumption,high stability has become a trend.At this time according to the carrier's orbital characteristics,satellite positioning system often use the Earth's free resources geomagnetic field to determine the attitude and adjustment.In practical engineering applications,in order to improve the application value of micro satellite,and meet the requirements of low cost and reliability,this paper designs a measuring module by using magnetometer as satellite attitude information,magnetic torque as the execution module to adjust the satellite attitude,the attitude determination system of nonlinear was designed to extended Calman filter algorithm based on satellite attitude calculation and Realization of the medium precision Micro-satellite attitude.Accuracy collection of information is needed in the satellite orbit,a high precision magnetic field vector collection system with low power consumption is designed.By the same time,in order to avoid the influence of hysteresis on the accuracy of the magnetometer acquisition system,in this paper,a reset circuit is used for the magnetic sensor and its function is verified experimentally;the overall accuracy of the acquisition system are tested and analyzed.The results show that the power consumption is 4.35 mA with magnetometer module,the measuring accuracy can reach 7nT.The the traditional Micro-satellite have problems with low precision,large memory,computation and so on,In order to solve these problems,this paper proposes extending Calman filter attitude solution algorithm,based on the four element number and angular velocity of the model to describe the attitude of the satellite information,the kinematics and dynamics model of micro satellite is given,and the state equation and measurement equation established and linearized.Finally,accuracy of the filtering algorithm is verified by simulation and the results show that :the satellite attitude angle aviation is less than 4 deg,the angular velocity error variance is less than 0.03 DEG /s.As an important part of attitude determination system,attitude adjustment module has the advantages of simple structure,high reliability,light weight and other characteristics,combining with the requirements of the magnetic torque as the executor attitude adjustment,and analysis the principle of magnetic torque,adjustment and calculating the method of magnetic converter,expounds the method to determine the size and number of turns of magnetic torque,analysis of test methods for properties of magnet and the output moment of experimental verification,Results show that the magnetic moment error is less than 0.03Am2,The output moment is 0.2Am2.The design of the geomagnetic Micro-satellite attitude determination system has a small volume,the low power consumption,fast responsing,simple structure,can satisfy medium precision of micro satellite attitude control needs.