Calibrating Linear Array Image Sensor Misalignment
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Solution Overview
Problem
Existing methods struggle to accurately calibrate absolute misalignment between attitude control sensors and high-resolution image payloads using linear array image sensors, as the operation schemes differ significantly from those employing two-dimensional plane sensors, making direct application of existing calibration methods difficult.
Innovation Solution
A method involving ground control point imaging, comparing operations, and calculating absolute misalignment estimation values using the DAVENPORT or QUEST algorithms, transforming image and position information into a form suitable for attitude determination, and calibrating the attitude control sensors to align the image payload with the satellite body coordinate system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing calibration methods are applied to linear array image sensors, then the calibration process becomes complex and inaccurate, but if new methods are developed, then the calibration accuracy improves while maintaining simplicity
Solution Approach 1:
The patent introduces ground control points as intermediary reference objects to bridge the calibration between the linear array image sensor and the attitude control sensor. By imaging these known reference points and comparing their positions, the system establishes a reliable reference framework that simplifies the calibration process while achieving high accuracy, avoiding the need for complex direct sensor-to-sensor calibration methods.
Solution Approach 2:
The patent replaces traditional mechanical alignment and calibration procedures with computational image processing and coordinate transformation methods. Instead of physically adjusting sensor positions, the system uses software-based algorithms to calculate and correct misalignment based on imaged ground control points, thereby simplifying the physical calibration process while maintaining or improving accuracy.
2Measurement precision
If ground control point imaging is performed multiple times for calibration, then calibration accuracy improves, but the time required for calibration increases
Solution Approach 1:
The patent applies partial action by performing calibration only in the necessary directions and using the minimum required number of ground control points to achieve the desired accuracy level. Rather than exhaustively calibrating all possible parameters multiple times, the method focuses on the critical misalignment parameters, achieving sufficient accuracy with reduced calibration time.
Solution Approach 2:
The patent implements feedback mechanisms where the imaged positions of ground control points are compared against their known reference positions, and the calculated misalignment information is used to correct the attitude control sensor data. This feedback loop allows the system to achieve high accuracy through iterative refinement without requiring excessive calibration time, as corrections are applied based on actual measured deviations.
Data Source
AI summary
Provided is a method for estimating and calibrating an absolute misalignment between an attitude control sensor of a satellite or a flight vehicle imaging and transmitting ground images having high resolution and an imaging payload.