Multi-Degree-of-Freedom Electromagnetic Machine for Singularity-Free CMG
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Solution Overview
Problem
Current control moment gyros (CMGs) face limitations due to singularities within their momentum envelope, leading to size, weight, and complexity issues, as they struggle to maintain attitude control without becoming 'stuck' in certain positions, and existing solutions either add unnecessary components or require higher torques.
Innovation Solution
A multi-degree-of-freedom electromagnetic machine with a first structure comprising spin and tilt conductors, along with a control system that supplies alternating current (AC) and direct current (DC) to these conductors, allowing continuous rotation about a spin axis and controlled tilting about a perpendicular axis, forming a surface shape with orthogonal trajectories, and utilizing a spherical structure with magnets to generate Lorentz forces for torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a two-axis gimbal with a second torque motor is added to mitigate singularities, then the CMG system can avoid singular positions, but the size, weight, and complexity of the system increase
Solution Approach 1:
The patent replaces the mechanical two-axis gimbal system with a magnetic field-based control system. Instead of using a second torque motor and gimbal mechanism to adjust momentum vector amplitude, the invention uses magnetic fields to exert forces on the spin axis, enabling singularity avoidance through field-based actuation rather than mechanical manipulation. This substitution eliminates the need for additional torque motors and gimbals, reducing device complexity while maintaining the ability to avoid singular positions.
2Reliability
If variable-speed operation is implemented to avoid singularities, then the CMG can maintain control, but much higher torques are required on the spin axis
Solution Approach 1:
The patent substitutes magnetic field-based actuation for mechanical torque application to the spin axis. By using magnetic fields to exert forces on the spin conductors, the system achieves variable-speed operation and singularity avoidance without requiring mechanically applied torques. This magnetic actuation method provides the necessary control authority with significantly reduced power requirements compared to traditional mechanical torque motors.
3Device complexity
If traditional CMG design is used, then the structure is simple, but the system becomes stuck at singular positions and cannot generate momentum
Solution Approach 1:
The patent introduces a magnetic field-based control system that replaces purely mechanical structures with electromagnetic actuation. The magnetic fields interact with spin conductors to provide continuous control authority throughout the momentum envelope, eliminating singular positions where traditional mechanical CMGs become stuck. This hybrid electromagnetic-mechanical approach maintains structural simplicity while dramatically improving reliability by eliminating singularity-related failures.
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 solution enables efficient and compact attitude control without singularities, reducing size and weight while maintaining precise control over spin and tilt, effectively addressing the limitations of traditional CMGs.
Implementation Method 1
The first spin conductor, the second spin conductor, and the tilt conductor together form a general shape of a surface. The second structure is disposed adjacent to the first structure and includes a plurality of magnets. Each magnet has at least one of its magnetic poles facing the surface.
Implementation Method 2
The control is configured to controllably supply alternating current (AC) to the first and second spin conductors and direct current (DC) to the tilt conductor, wherein the first structure continuously rotates about the spin axis in response to the AC being supplied to the first and second spin conductors, and rotates about the tilt axis to a tilt position in response to the DC being supplied to the tilt conductor.
Implementation Method 3
The second structure is disposed adjacent to the first structure and includes a plurality of magnets. Each magnet has at least one of its magnetic poles facing the surface.
Data Source
AI summary
A multi-degree-of-freedom electromagnetic machine includes a first structure, a second structure, and a control. The first structure is configured to rotate about a spin axis and about a tilt axis that is perpendicular to the spin axis, and includes a first spin conductor, a second spin conductor, and a tilt conductor, which together form a general shape of a surface. The second structure is disposed adjacent to the first structure and includes a plurality of magnets. The control is configured to controllably supply alternating current (AC) to the first and second spin conductors and direct current (DC) to the tilt conductor, wherein the first structure continuously rotates about the spin axis in response to the AC being supplied to the first and second spin conductors, and rotates about the tilt axis to a tilt position in response to the DC being supplied to the tilt conductor.