Research On Key Technology Of Geomagnetic-aided Matching Location

High-precision location and navigation is the core technology in a series of scientific research and military fields,such as geographic mapping,space exploration,and weapon guidance.The inertial navigation system is an extremely important means of carrier location because it can provide a comprehensive location and navigation information for the carrier while it has complete autonomy and concealment.However,the principle of inertial navigation determines that the error of time accumulation is an unavoidable defect and it cannot guarantee the long time location accuracy.As a geophysical field location technology,geomagnetic-aided matching location technology can effectively compensate for the shortcomings of inertial navigation systems.It is a hot spot in the field of current navigation and location research and has broad application prospects.In view of the difficulties and problems of geomagnetic assisted matching and location technology,this thesis focuses on two key technologies which are geomagnetic field upward/downward continuation technology and geomagnetic matching location algorithm.The details are as follows:(1)The error mechanism of the geomagnetic field upward continuation algorithm in frequency domain is analyzed and the improvement is proposedIn the process of discretization sampling,the frequency domain operator leads to aliasing in the spatial domain resulting in aliasing error.In addition,the edge effect error occurs when the geomagnetic field data is periodically convolved with the operator in the spatial domain.This thesis deduces and analyzes the mechanism of these errors,and gives the corresponding solution: To avoid aliasing errors,the maximum height of the upward continuation should not exceed 1/10 of the length of the line;In order to overcome the edge effect error,the potential field data that are more than 10 times the extension height should be added at both ends of the line.The correctness of the improvement of the error analysis is verified by simulations and real data.(2)Frequency domain downward continuation for geomagnetic field based on iterative regularization algorithm is proposedThe traditional downward continuation operator could amplify the data noise and cause the algorithm to be instability due to its high-pass filtering characteristics.This thesis proposes a downward continuation algorithm based on iterative regularization method using gradient descent iteration to minimize the cost function,so as to improve the frequency characteristics of the operator.The frequency operator of iterative regularization method converges to the regularization method of normal equation,but avoids the process of matrix inversion.The real data and simulation prove that the iterative regularization operator cannot only suppress high-frequency noise effectively,but also highlight the useful data in low and middle frequency,and achieve stable downward extension of geomagnetic field.(3)An improved matching location algorithm based on rotation searching is proposedFocusing on the problem that the original direction error of inertial navigation cannot be corrected by the traditional matching location algorithm based on correlation analysis which leads location results to diverge,this thesis proposes an improved matching location algorithm based on rotation searching,by rotating the inertia track to make it traversal the heading error angle to match one by one.It can effectively correct the initial heading error and improve the adaptability of the algorithm.(4)A dual-characteristics matching location algorithm based on total magnetic field and total field gradient is proposedAiming at the problem that the location precision is low when matching location algorithm uses a single characteristic in the region lacking geomagnetic fluctuation,this thesis proposes a dual characteristics matching location algorithm based on total magnetic field and total field gradient.This algorithm fuses both geomagnetic total field data and total field gradient data to give the best matching location results.Simulation results show that compared with traditional correlation matching algorithm and rotation searching matching algorithm,the location accuracy of this algorithm is further improved.(5)A geomagnetic-aided matching location experiment is carried outIn order to verify the actual effect of these geomagnetic matching localization algorithms,a geomagnetic aided location and experimental platform is designed and implemented in this thesis.Matching and location experiments have been done by dragging the non-magnetic vehicle.The experimental results show that the geomagnetic matching algorithm can effectively correct the location error of the pure inertial navigation system,and the performance of the algorithm is consistent with simulation results.The dual characteristics matching location algorithm has the highest accuracy,rotation searching matching algorithm comes second and the traditional correlation matching algorithm in the end.