Dynamic accuracy measurement method for star trackers using a time-synchronized high-accuracy turntable.

Area of Science:

• Spacecraft Attitude Determination
• Navigation Systems Engineering
• Optical Sensor Metrology

Background:

• Star trackers are critical for spacecraft attitude control, providing essential navigation data.
• Inaccurate attitude information from star trackers can lead to significant navigation errors and mission failure.
• Ground validation of star tracker accuracy, particularly under dynamic conditions, is challenging.

Purpose of the Study:

• To propose and validate a novel method for measuring star tracker accuracy under dynamic conditions.
• To overcome limitations of ground-based testing for highly dynamic star trackers.
• To enable comprehensive performance verification, including sensitivity and capture probability.

Main Methods:

• Utilized a high-accuracy synchronized swing table to simulate dynamic spacecraft motion.
• Employed coordinate transformations to predict initial star tracker attitude.
• Synchronized the swing table, star tracker, and test equipment to minimize systematic errors.
• Used real navigation stars as targets for measurement, unlike simulated star methods.

Main Results:

• The proposed method allows star trackers to maintain tracking at angular velocities up to 20°/s.
• Achieved more sufficient statistical sample points and reliable results due to continuous tracking.
• Measurements using real stars closely mimic on-orbit performance.
• Successfully verified multiple star tracker performance metrics in a single experiment.

Conclusions:

• The developed accuracy measurement method is effective for evaluating star trackers under highly dynamic conditions.
• The test environment closely replicates in-orbit conditions, meeting stringent dynamic performance requirements.
• This method provides a reliable approach for verifying star tracker accuracy and performance.