Theoretical error modeling and analysis of strapdown inertial navigation system alignment under zero-velocity...

Area of Science:

• Navigation Systems
• Geophysics and Geodesy
• Sensor Technology

Background:

• Initial alignment is critical for inertial navigation system (INS) operation.
• Fine alignment uses zero-velocity updates to correct navigation errors.
• The velocity-matching approach in fine alignment has observability limitations.

Purpose of the Study:

• To analyze the accuracy of the fine alignment algorithm.
• To investigate the influence of inertial measurement unit (IMU) attitude on alignment performance.
• To develop methods for predicting alignment accuracy based on orientation and sensor precision.

Main Methods:

• Observability analysis to identify unobservable error states.
• Analytical derivations and numerical simulations to study attitude effects.
• Statistical examination of sensor channel impacts (x, y, z) on alignment accuracy.

Main Results:

• Alignment accuracy is dependent on both sensor precision and IMU orientation.
• New relationships were derived to predict alignment accuracy for various orientations.
• Sensors along the z-channel exhibit a differential sensitivity, predominantly influencing final alignment accuracy.

Conclusions:

• IMU attitude significantly impacts fine alignment performance.
• Higher accuracy sensors allocated to the z-axis can optimize INS performance within budget constraints.
• The findings offer practical strategies for sensor placement to enhance navigation system accuracy.