Autonomous State Estimation and Observability Analysis for the Taiji Formation Using High-Precision Optical Sensors

Area of Science:

• Spacecraft navigation
• Astrodynamics
• Estimation theory

Background:

• Ground observation limitations during certain navigation mission phases.
• Inaccurate spacecraft tracking using dynamic equations and prior knowledge alone.
• Need for improved state estimation utilizing onboard measurements.

Purpose of the Study:

• To investigate onboard measurement selection for accurate Taiji formation spacecraft state estimation.
• To evaluate two schemes using interspacecraft interferometry and sensor data.
• To analyze system observability and error covariance propagation.

Main Methods:

• Numerical analysis of observability using singular value decomposition.
• Error covariance propagation analysis with the cubature Kalman filter.
• Design and simulation of two state estimation schemes.

Main Results:

• High-precision interspacecraft angle measurements significantly enhance system observability.
• Scheme 1 estimates absolute position and velocity with accuracies of ~3.1 km and ~0.14 m/s, respectively.
• Scheme 2, using radial velocity sensor data, improves velocity estimation accuracy by approximately 18 times compared to Scheme 1.

Conclusions:

• Onboard measurements, particularly interspacecraft interferometry, are vital for precise spacecraft state estimation.
• The proposed schemes offer significant improvements over traditional methods for navigation missions.
• Radial velocity sensor data provides substantial benefits for velocity estimation accuracy.