Research On Three-axis Satellite Attitude Simulation System

With the development of satellite technology, satellite attitude control hasbecome an important domestic and international research field, the attitudesimulation system based on the triaxial air-bearing platform, due to it’s physicalsetting for dynamics, has obvious advantages in the verification for system actualoperation condition and the attitude dynamic coupling.The triaxial air-bearingplatform has been widely used because of it’s real simulation effect.Firstly, this paper was written on the basis of three axis air-bearing platform.By researching the performance and technical indicators of the satellite attitudesimulation system, the general scheme of air-bearing platform control system wasproposed. The following functions were achieved: supply power for platform,compensation for the torque of gravity centre shift, acquisition of attitudemeasurement data in IMU for GNC computer and transmission of the instruction toattitude control actuators.Secondly, the paper introduced the hardware design of air-bearing platformcontrol system and the control boards design based on DSP chip TMS320F2812produced by TI company were realized. Among them, the platform powermanagement control circuit was consisted of power output module and voltagemonitoring module. Centre-of-gravity automatic adjustment system control boardcontained the force sensor data acquisition module,the fiber-optic gyroscope dataacquisition module and servo motor driver module. Attitude control system controlboard contained the attitude measurement data acquisition module of IMU, attitudecontrol actuator instruction transmission module and RS422serial communicationmodule for the information exchange with GNC control computer.Then, this paper introduced the development process of embedded softwaresystem. CCS3.3was chosen as integrated development environment. The followingmodules were realized: the related programs of power management system, themistake alarm module of power supply, the program of servo motor control and thedata acquisition for centre-of-gravity adjustment system. Besides, the program ofattitude measurement data acquisition and the control algorithm of attitude controlactuators were designed. The data preprocessing method of control boards wasintroduced in detail as well as the implementation method of serial communicationbetween control board and ground monitoring computer, between control board andGNC control computer. Meanwhile, the communication protocol was introduced. Inaddiion, the drive programs for AD7731used in force sensor data acquisition andTL16C752used in attitude control data transmission were described. Finally, the dynamics and kinematics model for three axis air-bearing platformwere established on this paper. the modeling process of wheel control and the jetcontrol was introduced in detail. The balance adjustment precision of air-bearingplatform and the interference torque values induecd by gravity shift, which was usedas three axis constant interference in air-bearing platform model were analyzed.With the help of SIMULINK, the dynamic and steady state performance of controlsystem were verified and the simulation results satisfied the requirement of satellitesimulation. Besides, the control characteristics and advantages of different attitudeactuators were analyzed.