Research On The Key Technology Of Integrated Navigation Based On Inertial Navigation,Celestial Navigation And Ground-based Pseudolite Naviagtion For Automated Transfer Vehicle

Taking the automated transfer vehicle as background,this dissertation studies the key technologies of the integrated navigation based on inertial navigation,celestial navigation and ground-based pesudolite navigation,aiming at high-precision strong-autonomy navigation services.According to the key problems,the corresponding solutions or improvement measures are put forward and verified by simulation experiments.Considering the flight characteristics of the automated transfer vehicle,the integrated navigation scheme is designed and its performance is analyzed by simulation.The semi-physical simulation system of the integrated navigation is developed and experiments based on such system are conducted.The main results and conclusions are as follows.(1)The noise analysis technique of inertial measurement unit and the accuracy of pure inertial navigation are studied.For the problem that how to estimate noise density accurately and objectively when using Allan variance techniques,an optimal iterative algorithm based on matrix transformation,sphere transformation and hyper-plane constraint is proposed.The test data analysis of the fiber optical gyro illustrates that the proposed algorithm has better estimation performance than the others.According to the perturbation equation of inertial navigation,the navigation accuracy is analyzed at the endpoint of the typical trajectory for automated transfer vehicle using pure inertial navigation under different conditions.The simulation results show that the navigation accuracy of position and velocity at the end of the vehicle typical track are about 6km and 0.34m/s with high level precision of initial states and inertial measurement unit,and about 15 km and 1.20m/s with middle level precision.(2)Some basic problems of celestial navigation are studied,such as star spot centroid extraction,star identification,attitude determinationand,and refraction star detection.For the fuzzy star spot in star sensor under vibration enviroment,the centroid extraction model aided by inertial measurement information is constructed and the aided centroiding algorithm is proposed.Simulation analysis shows that under vibration enviroment the centroid extraction precision of traditional algorithm decreases severely,while the aided algorithm's precision can still reach 1% pixel.For the lost-in-space mode of star sensor,the star identification algorithm based on the shortest distance mapping is proposed and its performance in small field of view is analyzed.Results show that the star identification success ratio can still reach 98% when the star spot centroiding error is within 0.5 pixel,the magnitude error is within 0.3 pixel and the number of missing star or false star is less than 2.For the tracking mode,the tracking strategy is designed and the tracking model with prior attitude information is established.Simulation results show that even the number of stars in star sensor is less than 3,the star identification success ratio in the tracking mode can also reach over 80% when the prior attitude precision is over 1°.Considering the system error of star sensor,an attitude determination algorithm based on the minimum square sum of the residual coorinate error of star spots is proposed.For the star sensor with 42? of single pixel angle resolution,the precision of the attitude determination algorithm is within 2? when the system error is less than 0.1 pixel.A refraction star detection method based on ?2 test is put forward,and the simulation result shows that there are only 2 false stars among the 766 refraction stars detected by the proposed method.(3)For the ground-based pesudolite navigation system,the evaluation method of pseudo range precision,the improved approach for positioning and the navigation precison evaluation method are studied.Utilizing some bad geometric configuration situations,a precision evaluation method of pseudo range and doppler for the ground-based pesudolite navigation system is presented.Simulation analysis indicates that the relative precision of pseudo range and doppler is within 5% with a short arm length(less than 4 m)when the precision of position and velocity from the external measurement system is more better than 40 m and 1.8m/s,respectively.An improved approach for positioning of ground-based pseudolite navigation system based-on receiver's clock error restriction is proposed,and the simulation results indicate that the position and velocity precisions of the improved algorithm in typical trajectory endpoint increase 15 times and 13 times compared with the traditional algorithm.A ground-based pseudolite navigation precision evaluation method with single experiment data is put forward which utilizes the navigaiton error converted by position dilution of precision for statistical accuracy.Simulation demonstrates that the navigation accuracy by the proposed method is in accordance with the one from multiple experiments,indicateing that the method can be used for navigation precison evaluation.(4)The performance of integrated navigation in different forms based on inertial measurement information,celestial measurement information and ground-based pesudolite measurement information is studied,and the effect of navigation sensor's precision on the integrated navigation performance is also analyzed.Based on the state euqations and observation equations of the corresponding integrated navigation,the integration simulation experiments are analyzed with the virtual accelerometers observation,inertial navigation/celestial navigaion,inertial navigation/ground-based pesudolite navigaion and inertial navigation/celestial navigaion/ground-based pesudolite navigaion.The results indicate that the integrated navigation performance can be improved with the addition of celestial measurement information and ground-based pesudolite measurement information.The final precision of position,velocity and attitude can reach 10.4m,0.001m/s and 0.2? respectively.(5)The research on the semi-physical simulation system of the integrated navigation based on inertial navigation,celestial navigaion and ground-based pesudolite navigaion is carried out.The general scheme of the semi-physical simulation system is designed and the celestial navigaion semi-physical system part is built.Based on the completed part of the semi-physical simulation system,the integrated navigation experimrnt has been carried out.The results indicate that the precision of position,velocity and attitude can reach 11.1m,0.001m/s and 1.7" at the end of the vehicle track,respectively.