Strapdown Inertial Navigation System Transfer Alignment

Transfer alignment in strapdown inertial navigation systems refers to the process of transmitting high-precision navigation information from a master inertial navigation system (such as the primary INS on an aircraft) to a slave inertial navigation system (such as subsystems on missiles or UAVs). This technique is primarily used to ensure the initial alignment accuracy of slave systems, thereby enhancing overall navigation performance.

The core of transfer alignment lies in utilizing the master system's attitude, velocity, and position data to initialize the slave system through specific algorithms (such as velocity matching, attitude matching, or a combination of both). Common implementation methods involve Kalman filtering to estimate and compensate for error sources in slave systems, including installation errors and gyroscope drift.

Implementing transfer alignment in MATLAB typically involves the following steps: Data Preprocessing: Acquire reference data (velocity, attitude, etc.) from the master system and perform noise filtering and time synchronization processing using functions like `filter()` or `synchronize()`. Error Modeling: Establish error equations for the slave system, including bias models for gyroscopes and accelerometers through state-space representation with `ss()` or custom mathematical modeling. Filter Estimation: Employ Kalman filter or extended Kalman filter (EKF) algorithms using `kalman()` or custom EKF implementations to perform real-time estimation and correction of error states. Accuracy Evaluation: Compare navigation errors before and after transfer alignment through simulation or measured data, calculating root mean square error (RMSE) or cumulative errors for position, velocity, and attitude using functions like `rmse()` or statistical analysis toolboxes.

The key to accuracy evaluation lies in analyzing the convergence speed and steady-state error of transfer alignment, which directly impacts the operational effectiveness of slave systems. In practical applications, environmental disturbances (such as vibrations or maneuver conditions) affecting alignment accuracy must also be considered, often requiring Monte Carlo simulations or robustness testing in implementation.