Star Tracking Sensor Navigation System Alignment
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Solution Overview
Problem
Conventional celestial-aided navigation systems require highly precise alignment and stability between star tracking sensors and inertial sensors to correct for position errors, limiting their flexibility and accuracy, as they rely on precise orientation to determine position from the angle between the sensor and the local vertical axis.
Innovation Solution
A navigation system that calculates the expected direction of celestial objects and uses this information to measure their actual direction, allowing for position determination without the need for precise alignment between star tracking and inertial sensors, enabling independent movement of the star tracking sensor relative to the inertial sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If highly precise alignment and stability between star tracking sensor and inertial sensor is maintained, then position correction accuracy is improved, but system flexibility and ease of operation deteriorate
Solution Approach 1:
The system separates the star tracking sensor and inertial sensor into independent units that do not require precise alignment. The star tracking sensor measures angles to celestial objects independently, while the inertial sensor provides motion data separately. These segmented sensor functions are then integrated through software processing to achieve accurate position correction without mechanical alignment constraints.
Solution Approach 2:
The patent introduces an intermediary computational process that mediates between the star tracking sensor measurements and inertial sensor data. This intermediary processing layer calculates position corrections by comparing expected celestial object positions with actual measurements, bridging the gap between the two independent sensors without requiring precise physical alignment between them.
2Stability of the object's composition
If star tracking sensor is mounted in close proximity to inertial sensor on the same platform, then alignment stability is improved, but device complexity and adaptability worsen
Solution Approach 1:
The system segments the sensor platform into independent mounting locations. The star tracking sensor and inertial sensor can be mounted at different positions and orientations on the platform without requiring close proximity or precise alignment. This segmentation allows each sensor to be optimally positioned for its specific function while maintaining overall system stability.
Solution Approach 2:
The patent creates a universal navigation system architecture that can accommodate various sensor configurations and platform types. The system is designed to work with star tracking sensors and inertial sensors regardless of their relative positions or orientations on the platform, providing multi-functional adaptability across different application scenarios without requiring specific alignment conditions.
3Measurement precision
If precise orientation between star tracking sensor and local vertical axis is maintained, then position determination accuracy is improved, but manufacturing precision requirements worsen
Solution Approach 1:
The patent replaces the mechanical alignment system with an optical and computational system. Instead of relying on precise mechanical mounting of the star tracking sensor relative to the local vertical axis, the system uses the star tracker's natural reference to celestial objects and computational algorithms to determine position. This substitution eliminates the need for high-precision mechanical manufacturing and alignment while maintaining or improving position determination accuracy.
Solution Approach 2:
The system changes the reference parameters from mechanical orientation angles to celestial object coordinates. By measuring angles to known celestial objects and comparing them with predicted positions, the system determines orientation and position without requiring precise knowledge of the sensor's mechanical orientation relative to the local vertical axis. This parameter transformation reduces manufacturing precision requirements.
Data Source
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AI summary
One embodiment is directed towards a method of navigating a body. The method includes determining a respective measured direction of each of a plurality of celestial objects with respect to the body based on an output of one or more star tracking sensors mounted to the body. Calculating an expected direction of at least one of the plurality of celestial objects with respect to the body based on a current navigation solution for the body. Calculating an updated navigation solution for the body based on the expected direction of the at least one celestial object, the measured direction of the plurality of celestial objects, and an output of one or more inertial sensors mounted to the body.