Satellite Attitude Control via Speed Axis Rotation
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Solution Overview
Problem
The existing optical satellites face challenges in maintaining stability and reducing drag due to movable deflection mirrors and the need for expensive and heavy inertial actuators, which increase mass and design costs, while also requiring adjustments in orientation for optimal solar radiation and battery charging in Low Earth Orbit.
Innovation Solution
A method for controlling the attitude of a satellite using a fixed line of sight optical instrument, where the satellite rotates only around the speed axis to point the line of sight towards regions to be imaged and optimize solar radiation, with a reduced torque capacity along the Y and Z axes compared to the X axis, allowing for a lighter and more efficient design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a movable deflection mirror is used to orient the line of sight, then the satellite can point towards the area to be observed, but the quality of the shot deteriorates due to reduced stability of the line of sight
Solution Approach 1:
Instead of moving the deflection mirror to change the line of sight direction, the invention inverts the approach by rotating the entire satellite body around its speed axis. This allows the fixed optical instrument's line of sight to sweep across the observed area while maintaining stability, as the rotation occurs around the velocity vector which naturally points along the orbital path.
2Ease of operation
If a movable deflection mirror is used to orient the line of sight, then the satellite can point towards the area to be observed, but the mass and size of the satellite increase
Solution Approach 1:
The invention extracts and eliminates the movable deflection mirror from the satellite system. By removing this component entirely, the satellite achieves orientation capability through body rotation around the speed axis, thereby reducing mass and simplifying the overall system while maintaining the ability to point the optical instrument at the desired area.
3Use of energy by moving object
If the satellite changes orientation between operating and standby statuses, then the solar generator can be optimized for battery recharging, but the drag increases due to larger frontal surface area
Solution Approach 1:
The invention applies dynamic control of the satellite's rotation around the speed axis to simultaneously optimize both solar power generation and drag reduction. By continuously adjusting the rotation angle based on the satellite's position in orbit and the sun's position, the system maintains the solar generator's optimal orientation toward the sun while keeping the frontal surface area minimized, thus balancing energy generation and drag reduction throughout the orbital cycle.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances image quality by maintaining stability, reduces satellite mass and cost, and optimizes solar power generation by minimizing the frontal surface area while maintaining efficient attitude control, thus improving overall performance and reducing drag.
Implementation Method 1
at least one solar generator fixed relative to the main body defining a functional surface whose normal has at least one component perpendicular to the speed axis
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
The invention relates to a method for controlling the guidance of attitude of a satellite (1), the satellite comprising an optical instrument (2), and a solar generator (4) defining a functional surface. The method comprises a first step of transmission (104) of guidance control for pointing the sighting axis (V) of the optical instrument in the direction of regions (7) to be imaged and a second step of transmission (106) of guidance control for orienting the normal (N, Na, Nb) towards the functional surface in the direction of the solar radiation. The guidance controls only relate to the rotation of the satellite about the speed axis (X), the angle of rotation about the orbit axis (Y) and the nadir axis (Z) in the orbital reference frame being maintained at substantially zero.