Vehicle Attitude Calibration via Inter-Satellite Angular Deviation
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Solution Overview
Problem
Existing methods for estimating the attitude of spacecraft using phase measurements of radioelectric signals are hindered by spatial errors caused by phase biases, which vary between reception antennas and are not compensated, leading to inaccuracies in attitude estimation.
Innovation Solution
A method that calibrates spatial errors by estimating inter-satellite angular distances in two ways: theoretically based on satellite positions and estimated based on phase measurements, allowing for the comparison and correction of spatial errors without requiring an additional attitude tracker, using a parametric model to reduce calculations and storage needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase measurements are used to estimate attitude, then attitude estimation is achieved, but spatial errors from phase biases reduce measurement precision
Solution Approach 1:
The patent applies preliminary action by pre-calibrating spatial errors using inter-satellite angular distances before using phase measurements for attitude estimation. The system预先 determines error characteristics from satellite geometry and applies corrections to subsequent measurements, eliminating the need for real-time complex error modeling and improving measurement precision proactively
Solution Approach 2:
The patent changes parameters by using inter-satellite angular distances as an additional calibration parameter that is independent of spacecraft attitude. By incorporating this geometric parameter from satellite ephemeris data, the system creates a reference frame that remains stable regardless of the spacecraft's orientation, thereby compensating for phase bias spatial errors
2Measurement precision
If an additional attitude tracker is used to calibrate spatial errors, then calibration accuracy is improved, but device complexity increases
Solution Approach 1:
The patent uses copying by creating a virtual reference system through inter-satellite angular distances calculated from satellite ephemeris data. Instead of physically installing additional attitude trackers, the system copies the reference frame information from ground-based satellite orbital data, providing a virtual calibration reference that eliminates the need for duplicate hardware
Solution Approach 2:
The patent introduces an intermediary by using inter-satellite angular distances as a mediating parameter between the phase measurements and the true attitude. This intermediary quantity, derived from independent satellite position data, serves as a bridge to calibrate the phase measurement system without requiring direct physical comparison with another attitude sensor
3Measurement precision
If multiple transmitters are considered for attitude estimation, then estimation precision is improved, but calculation complexity increases
Solution Approach 1:
The patent changes parameters by transforming the problem from solving complex phase difference equations with multiple transmitters to using inter-satellite angular distances as a simplified calibration parameter. This parameter transformation reduces the mathematical complexity while maintaining the benefit of using multiple satellite signals for improved precision
Data Source
AI summary
A method for calibrating spatial errors induced by phase biases having a detrimental effect on the measurements of phase differences of radio signals received by three unaligned receiving antennas of a vehicle. An inter-satellite angular deviation of a pair of satellites is estimated in two different ways: on the basis of the respective positions of the vehicle and of the satellites to obtain a theoretical inter-satellite angular deviation; and on the basis of the respective directions of incidence of the satellites relative to the vehicle, which are determined from phase measurements, to obtain an estimated inter-satellite angular deviation. The space errors are estimated on the basis of said theoretical and estimated inter-satellite angular deviations. Also, a method and system for estimating the attitude of a vehicle, in particular a spacecraft.