Research On Micro-Satellite Attitude And Orbit Autonomous Determination

Micro-Satellite is one of hotspots in space technology domain currently. It's significative to enhance micro-satellite attitude determination technology to improve performance of micro-satellite platform, and autonomous orbit determination of constellation composed of micro-satellites is attractive while the increasing number of micro-satellites and space safety stress. In this dissertation, micro-satellite attitude determination and constellation autonomous orbit determination based on inter-satellite ranges is researched, which mainly consist of following parts:Because micro-satellite attitude determination system(ADS) is strictly restricted by cost, mass and power, so available attitude sensors are less, then attitude determination technology based on new subminiature attitude sensors with low power consumption is researched. COMS camera is adopted to image the earth rim, and correction method is derived to conquer earth rim image deformation which is produced by angle mounting and control error, consequently, the geocentric vector observation is achieved using nonlinear least squares estimation, the effect of the method is verified by simulation. Some functions of GNSS receiver can be realized in onboard computer, so ADS will be more subminiature if GNSS attitude determination technology is adopted. GPS ambiguity quick search algorithm based on short baseline and single carrier is presented and attitude resolution flow is designed. A GPS attitude determination system is established on ground and the results indicate the method is available. Ambiguity quick resolution method based on Three-Carrier Ambiguity Resolution(TCAR) Technique using Galileo system is researched, and a method based on a small ambiguity space and optimized ambiguity search algorithm is presented by analysis of probability distribution of integer ambiguity resolution by TCAR. It wins a higher success probability of integer ambiguity determination and save the initialization time.Adopting new information fusing method is effective to enhance precision and reliability for micro-satellite attitude determination. Predictive filtering is introduced into satellite attitude determination to conquer influence of non-gauss error which can't be modeled to improve attitude determination performance for satellite without gyros. Lower design criterion of model error weight matrix is presented, so filter design is simplified and the oscillation at initial time is conquered. A improved federal filtering is presented to fuse multi-information from low precision attitude sensors. Prediction and distribution information are done in main filter, and only measurement renovating is processed by local filters. The method is with low computing cost and high tolerance.On-orbit calibration is an effective approach to improve attitude determination accuracy using micro attitude sensors of low precision. The satellite attitude dynamics including satellite remanence disturbing torques and magnetometer bias observing model are established. Simulation results indicate that calibration algorithm works well. A MEMS gyro bias real-time on-orbit calibration model independent of any other sensors is presented, and applicable conditions of the algorithm are derived. Simulation results show that the calibration algorithm is accurate, and is suitable for satellite orbit injection phase.Autonomous orbit determination of micro-satellite constellation relying on inter-satellite range is researched. According to constellation composed of numerious micro-satellites, observability of inter-satellite range is analyzed and inter-satellite range model and key simulation methods are given, then precision analysis for inter-satellite range is processed, and simulation proves the method is effective. Furthermore, satellite-ground range is introduced to fix the whole constellation, and the simulation validates the blue print is feasible and presents a solution for micro-satellite constellation long time autonomous orbit determination.A simulation platform for attitude determination and control system(ADCS) is constructed by STK and Matlab. Quick design and validating for attitude determination algorithm and control law is available using the platform, so designer's burden is lightened. According to the ADCS tasks of a certain micro-satellite, the system configuration, components arrangement, task flow and essential algorithm are introduced, then ADCS software developing and semi-physics simulation platform is made based on PC104 embeded computer and VxWorks RTOS, and the scheme, task design and algorithm are proved to be correct.The research work in the dissertation is useful for further developing of micro-satellite attitude and orbit autonomous determination technology, and is valuable in theory and engineering.