Satellite Attitude Control for Solar and Thermal Constraints
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Solution Overview
Problem
Current attitude control methods for Earth observation satellites in inclined orbits are inadequate as they only offer one degree of freedom to direct the observation instrument, fail to optimize solar panel sunlight during long observation periods, and do not adequately consider heat dissipation and stellar sensor constraints related to the Sun.
Innovation Solution
A method for controlling the attitude of satellites in orbit around a celestial body, involving rotations around orthogonal axes to orient the observation instrument, solar panel, and stellar sensor, ensuring minimum solar panel insolation, maximum radiator insolation, and avoiding stellar sensor exposure to the Sun, while maintaining a substantially constant yaw attitude to minimize mechanical disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the satellite attitude is controlled to maintain the Y axis orthogonal to the orbit plane, then the solar panel sunlight is optimized, but only one degree of freedom is available to direct the observation instrument
Solution Approach 1:
The patent introduces a new degree of freedom by allowing the satellite attitude to deviate from the traditional orbit-plane-orthogonal orientation. By defining a reference plane that includes the orbit normal and the Sun direction, and allowing rotation around this reference plane normal, the system gains an additional rotational dimension. This enables simultaneous optimization of both power supply and observation coverage without mechanical modifications.
2Productivity
If the satellite observes Earth for extended periods, then observation productivity increases, but solar panel insolation becomes insufficient during activity periods
Solution Approach 1:
The patent implements dynamic attitude adjustment by continuously adapting the satellite orientation based on the satellite-Sun-observation target geometry. The reference plane is dynamically recalculated to include the current Sun direction, and the yaw angle is adjusted in real-time to maximize solar panel insolation while maintaining observation capability. This dynamic approach allows extended observation periods without sacrificing power supply.
3Use of energy by moving object
If the attitude control only considers solar panel constraints, then power supply is optimized, but heat dissipation and stellar sensor constraints are violated
Solution Approach 1:
The patent applies different orientation requirements to different satellite components by defining component-specific constraint zones. The reference plane and yaw angle are calculated to simultaneously satisfy: (1) solar panel insolation constraints, (2) radiator heat dissipation constraints by orienting radiating surfaces away from the Sun, and (3) stellar sensor constraints by keeping the sensor field of view away from the Sun. This localized quality approach ensures each component operates within its optimal constraints.
4Use of energy by moving object
If yaw attitude varies during observation phases, then solar panel insolation is maximized, but mechanical disturbances increase
Solution Approach 1:
The patent implements a hybrid control strategy where the yaw attitude is held constant during observation phases to minimize mechanical disturbances, and adjusted during transition phases to optimize solar panel insolation for the next observation target. This periodic action between constant-yaw observation modes and adjustment modes reduces mechanical activity while maintaining power supply efficiency throughout the extended observation period.
Data Source
Figure 1a~1b
Figure 2a~2b
Figure 2c~2d
AI summary
The invention relates to a method for controlling the attitude of a satellite (1,2) in orbit around a celestial body, said satellite comprising an observation instrument (10,20), a solar panel (11,21a), a radiator (12,22), and a stellar sensor (13,23) which are arranged on the satellite (1,2) such that, in a reference point associated with said satellite and predetermined by three orthogonal axes X, Y, and Z therebetween, the observation instrument (10,20) is arranged such that the observation axis thereof is parallel to the Z axis of the satellite, the solar panel (11, 21a) is parallel to the Y axis, the radiator (12,22) is arranged on one of the surfaces -X, +Y, or -Y of the satellite, and the stellar sensor (13,23) is guided from the negative X side. According to the method, the attitude of the satellite (1,2) is controlled during a rolling and pitching activity period (J) to guide the observation instrument (10,20) towards two areas to be observed on the celestial body, and the twisting attitude of the satellite (1,2) is controlled to keep the sun on the positive X side and ensure that a minimum solar radiation stress C1 on the solar panel (11,21a) is confirmed during observation phases of said activity period.