Satellite Attitude Control for Thrust and Solar Array Alignment
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Solution Overview
Problem
Existing electric propulsion systems for satellite orbit transfer face challenges in achieving autonomous control due to high operational load on ground stations and limited computing capabilities on satellites, leading to inefficient orbit transfer times and reduced power generation efficiency of solar array panels.
Innovation Solution
An orbital attitude control device and method that calculates control torque using an evaluation function to maintain the orthogonality between the solar array panel's rotational axis and the solar direction, enabling autonomous orbit transfer with high power generation efficiency by utilizing a computing machine on the satellite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If ground station calculates attitude schedule and uploads to satellite, then autonomous control capability is improved, but operational load on ground station increases and ground station dependency increases
Solution Approach 1:
The satellite's onboard computing machine performs attitude schedule calculation autonomously using the evaluation function and optimization algorithm, eliminating the need for ground station computation. The satellite serves itself by having its own computer calculate the attitude schedule based on stored orbital elements and solar direction data, thereby reducing ground station operational load while maintaining autonomous control capability.
2Loss of substance
If electric propulsion thruster is used for orbit transfer, then propellant consumption is reduced, but orbit transfer time increases significantly
Solution Approach 1:
The system dynamically adjusts the satellite attitude in real-time to optimize both thrust vector direction and solar array power generation efficiency. By continuously calculating the optimal attitude schedule that satisfies multiple constraints (thrust direction, solar perpendicularity, actuator limits), the system maximizes the effectiveness of electric propulsion while minimizing transfer time through continuous rather than intermittent thruster operation.
Solution Approach 2:
The evaluation function optimizes multiple parameters simultaneously including attitude angles, thrust vector direction, and timing of thruster operation. By changing these parameters dynamically based on the satellite's orbital position and solar direction, the system achieves efficient propellant utilization while reducing transfer time through optimized continuous thrust application.
3Use of energy by moving object
If satellite attitude is controlled to maximize solar array power generation, then power generation efficiency is improved, but thrust vector direction may deviate from optimal orbit transfer direction
Solution Approach 1:
The attitude schedule is dynamically calculated to satisfy both solar array optimization constraints and thrust vector direction constraints simultaneously. The system adjusts attitude angles in real-time based on the satellite's position and solar direction, ensuring that at any given moment, the attitude optimally balances power generation efficiency with orbit transfer effectiveness, rather than prioritizing one over the other statically.
Solution Approach 2:
The unified attitude control system serves multiple functions simultaneously: it maximizes solar array power generation, maintains optimal thrust vector direction for orbit transfer, and respects actuator drive constraints. The evaluation function integrates multiple objectives into a single optimization problem, allowing the attitude control to universally address both power generation and orbit transfer efficiency requirements.
4Manufacturing precision
If attitude control actuator operates to follow ideal attitude, then thrust vector direction accuracy is improved, but actuator drive constraints may be violated
Solution Approach 1:
The attitude schedule is dynamically optimized considering actuator drive constraints as part of the evaluation function. Rather than attempting to follow an ideal attitude that may require excessive actuator movement, the system calculates a realistic attitude schedule that achieves sufficient thrust vector direction accuracy while respecting actuator speed, acceleration, and position limits, ensuring reliable operation throughout the orbit transfer.
Data Source
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AI summary
In an orbital attitude control device (1150), an ideal thrust axis direction calculator (1505) calculates an ideal thrust axis direction based on information of a predetermined orbit, an ideal attitude calculator (1506) calculates an ideal attitude of the satellite based on the ideal thrust axis direction and a solar direction, and a control torque calculator (1510) calculates a control torque to control the attitude control actuator based on an estimation attitude of the satellite, the solar direction, a preset drive constraint, and the ideal attitude. The control torque calculator (1510) calculates an ideal control torque that makes the attitude of the satellite follow the ideal attitude and a torque restraint plane in which the solar direction is orthogonal to a rotational axis of the solar array panel, defines an evaluation function obtained by weighting a distance from the ideal control torque and a distance from the torque restraint plane and then summing the weighted distances, and calculates the control torque that allows the drive constraint to be satisfied and the evaluation function to be minimized.