Research On Transfer Alignment Method Based On Airborne Distributed Inertial Measurement Systems

In the aerial earth observation system,high-precision navigation information at the sub-antenna can be achieved by transferring alignment.Different from shipboard,vehicle-mounted and other systems,the working environment of airborne distributed inertial measurement system is complex and the structural deformation is serious.The problems related to the transfer alignment technology research are also more complex.Firstly,the five key technologies involved,the modeling of wing deflection and deformation modeling,decoupling of carrier movement and deflection deformation,deflection error compensation,lever arm effect error compensation,and multi-node global information fusion are analyzed,and the overall research plan of the system is given.Secondly,based on the theory of thin plate,the deflection model of wing is established,and the experimental platform of FBG deformation measurement of wing is built.Curve fitting is carried on by processing the wavelength change data which is obtained by the fiber demodulator.After that,the 1:1 wing model is used to analyze the deformation displacement of the wing under different loads in COMSOL multiphysical software,results are compared with the data from the curve fitting model to verify the accuracy of the model.The experiment shows that the accuracy of the fiber grating deflection measurement deformation can reach the mm level.Then,based on the geometric relationship of the motion parameters between the main system and the sub-system,the coupling angle model of the wing deflection and the carrier motion is established.Combined with the coupling angle model,the relationship of motion parameters between the main system and the sub-system is derived again,and the measurement equation model in the transfer alignment filter is optimized.On the basis of the above,the airborne distributed transfer alignment filter model is given.Compare with the traditional transfer alignment filter which does not consider the coupling angle and simply deals with the bending deformation angle,the simulation and semi-physical simulation results show that compared to the traditional method,the transfer alignment method proposed in this paper,has fast convergence and high accuracy.At last,a fusion scheme of transfer alignment information of the main multi-sub airborne distributed inertial measurement system is given,and the effectiveness and feasibility of the distributed multi-node transfer alignment method in this paper are verified by semi-physical simulation experiments.The results show that the model accuracy angle accuracy of the proposed model is improved by about 34%,and the position error accuracy is improved by an order of magnitude.