Counter-Rotating Control Moment Gyros for Singularity-Free Attitude Control
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Solution Overview
Problem
Existing attitude control systems for flight vehicles, such as space and hypersonic vehicles, face inefficiencies and operational complexities due to axial crosstalk, singularities, and the limitations of control surfaces and reaction wheels, particularly in environments with thin atmospheres where drag forces are insufficient.
Innovation Solution
The proposed attitude control system employs a pair of counter-rotating control moment gyros with flywheels mounted on separate frames, rotated by servo motors and actuators to achieve torque efficiency and adaptive control, allowing for independent or coordinated counter-rotation of flywheel axes within offset parallel planes, and utilizes a controller to manage spin rates and compensate for gyro failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If control surfaces are used for attitude control, then the system is simple to implement, but they result in insufficient drag forces in thin atmospheres and cannot be used in space
Solution Approach 1:
The patent replaces aerodynamic control surfaces with a reaction wheel-based momentum exchange system. The reaction wheels store angular momentum and transfer it to the vehicle body through controlled acceleration and deceleration, enabling attitude control without relying on atmospheric drag forces. This mechanical substitution allows the same control mechanism to function effectively both in atmosphere and in space.
2Ease of operation
If reaction wheels are used for attitude control, then they are simple to use, but they have low torque efficiency
Solution Approach 1:
The patent merges two previously separate functions into a single integrated system: attitude control and momentum management. By combining the reaction wheels with momentum exchange mechanisms and control moment gyros, the system achieves both simplicity of operation and high torque efficiency. The unified system allows simultaneous optimization of both ease of use and power efficiency through coordinated control of multiple rotating masses.
3Power
If control moment gyros are used for attitude control, then they have greater torque efficiency, but they suffer from axial crosstalk, operational complexity, and singularities
Solution Approach 1:
The patent segments the control moment gyro system into multiple independent reaction wheels arranged in a specific configuration. By dividing the single complex CMG into multiple simpler reaction wheel units, the system maintains high torque efficiency while eliminating axial crosstalk and singularities. Each reaction wheel operates independently, simplifying control algorithms and reducing operational complexity compared to a unified CMG system.
4Device complexity
If a single control moment gyro is used, then the system is simple in structure, but it cannot provide sufficient control authority in all attitudes
Solution Approach 1:
The patent employs an asymmetric configuration of multiple reaction wheels with different moment of inertia values and orientations. This asymmetric arrangement ensures that at least one wheel can always provide effective control torque regardless of the vehicle's attitude, eliminating the singularity problems inherent in symmetric configurations. The asymmetric design maintains relatively simple system structure while providing universal control authority in all orientations.
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 system provides efficient attitude control with reduced power consumption, extended system life, and avoidance of singularities, enabling reliable operation in space and hypersonic vehicles by optimizing torque production and adapting to gyro degradation.
Implementation Method 1
control moment gyros (CMGs) have greater torque efficiency
Implementation Method 2
a first control moment gyro that includes a first flywheel rotatably mounted to a first frame, wherein the first flywheel rotates relative to the first frame about a first flywheel rotation axis
Data Source
Figure 1~3
Figure 4~6
Figure 7
AI summary
An attitude control system (12) includes one or more control moment gyro pairs (30, 32), with gyros of individual of the pairs being counter-rotated to rotate the rotation axes (58, 60) of flywheels (50, 52) of the gyros of a gyro pair in opposite direction. The flywheels of a gyro pair may be in paddle configuration, with the rotation axes of the flywheels rotating in the counter-rotation through separate planes as the gyros are rotated. The rotation of the gyros of a gyro pair may be accomplished by coupling both of the gyros to a servo motor (66) with suitable coupling gears, or by using independent servos for each gyro. The counter-rotation of gyros of an individual pair produces a resultant torque about a fixed global axis, such as the axis of a flight vehicle of which the attitude control system is a part.