LCEF Frame Strapdown Inertial Navigation Update
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Solution Overview
Problem
There is no effective method for updating strapdown inertial navigation solutions based on the launch-centered earth-fixed (LCEF) frame, which is crucial for medium-to-short-range surface-to-surface missiles, affecting the accuracy and consistency of missile guidance systems.
Innovation Solution
A method is developed to update strapdown inertial navigation solutions using the LCEF frame, involving attitude, velocity, and position updates through quaternion methods, equivalent rotation vectors, and error compensation algorithms, ensuring accurate data alignment with flight control and guidance systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the LCEF frame is used as the navigation reference frame, then the accuracy of attitude and position calculations is improved, but the complexity of the navigation algorithm increases
Solution Approach 1:
The patent introduces an intermediary transformation relationship between the LCEF frame and traditional frames (LL/LCI). By establishing transformation matrices and quaternion relationships as intermediaries, the patent enables accurate attitude and position calculations in the LCEF frame while leveraging existing mature algorithms from traditional frames, thus reducing the direct complexity of implementing navigation in the LCEF frame.
Solution Approach 2:
The navigation algorithm is segmented into distinct modules: attitude update using quaternions, velocity update, and position update. Each module handles specific calculations independently, which reduces overall algorithm complexity while maintaining high accuracy in the LCEF frame.
2Reliability
If error compensation algorithms are applied to account for linear and angular vibrations, then the hit rate of missiles is improved, but the calculation load increases
Solution Approach 1:
The patent applies partial error compensation by focusing on the most significant error sources (linear and angular vibrations) rather than compensating for all possible errors. This selective approach improves missile hit rate by addressing the dominant error mechanisms while keeping the calculation load manageable for embedded systems.
Solution Approach 2:
The patent changes the computational parameters by using quaternion-based attitude updates and specific error compensation models that are computationally efficient. By optimizing the mathematical parameters and update frequencies, the system achieves reliable hit rates without excessive calculation load.
3Stability of the object's composition
If the LCEF frame is used instead of LL/LCI frames, then the consistency of missile parameters with control and guidance systems is improved, but the maturity of updating methods is reduced
Solution Approach 1:
The patent uses transformation matrices and quaternion relationships as intermediaries to bridge the LCEF frame with traditional navigation frames. This allows the system to maintain consistent missile parameters with control and guidance systems while still benefiting from the mathematical maturity of established navigation algorithms through the intermediary transformation layer.
Data Source
AI summary
The present invention relates to a method for updating strapdown inertial navigation solutions based on a launch-centered earth-fixed (LCEF) frame (g frame). The present invention uses the g frame as a navigation reference frame of a medium-to-short-range surface-to-surface missile. This is beneficial to establish a relative relationship between the missile and the ground so as to keep the same missile parameters required by a missile control and guidance system. The calculation of a navigation algorithm in the g frame is moderate, which is suitable for an embedded system.