Dynamic CMG Array Reorientation for Spacecraft Momentum Control
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Solution Overview
Problem
Existing spacecraft momentum control systems using control moment gyros (CMGs) face challenges in maintaining optimal momentum control when CMGs fail or when spacecraft mass properties change, leading to reduced control capabilities and inefficiencies.
Innovation Solution
The system allows for the reorientation of CMGs around an axis not parallel to the gimbal axis, using a bearing between the CMG base and mount, with releasable clamps for rotation, and a controller that determines and implements new orientations to maximize momentum control space, either pre-launch or in-orbit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If CMGs are fixed in initial orientation, then manufacturing and installation are simplified, but momentum control space is reduced when mass properties change or CMGs fail
Solution Approach 1:
The CMG array transitions from a static fixed-orientation configuration to a dynamic reconfigurable system. Each CMG is equipped with a drive mechanism that enables rotation about an axis not parallel to the gimbal axis, allowing the array to adapt its orientation in response to CMG failures or changes in spacecraft mass properties, thereby maintaining optimal momentum control space throughout the mission.
Solution Approach 2:
The system changes the orientation parameters of the CMGs dynamically. By rotating CMGs about a non-parallel axis, the array can alter its geometric configuration to compensate for mass property changes or failures, optimizing the momentum control space for different mission phases and conditions.
2Productivity
If CMG array is designed for optimal initial orientation, then initial performance is maximized, but reliability decreases when CMGs fail
Solution Approach 1:
The system prepares for future failures by incorporating redundancy and adaptability into the CMG array design. The non-parallel rotation capability and reconfiguration algorithms are built in advance, allowing the array to maintain momentum control capability even after one or more CMGs fail, thus cushioning against the reliability degradation that would otherwise occur.
Solution Approach 2:
The CMG array becomes a dynamic system that can reconfigure its geometry in response to failures. By rotating remaining functional CMGs about non-parallel axes, the array maintains momentum control space and continues operation, transforming from a static vulnerable configuration to a dynamic resilient one.
3Adaptability or versatility
If CMGs are made reconfigurable with rotation capability, then adaptability to mass property changes is improved, but device complexity increases
Solution Approach 1:
The CMG array incorporates controlled dynamic elements (rotation mechanisms about non-parallel axes) that enable adaptability to mass property changes and failures. This dynamic capability allows the system to optimize momentum control space by reconfiguring CMG orientations in response to changing mission requirements and spacecraft conditions.
4Loss of time
If CMG orientation is fixed at launch, then initial setup time is reduced, but in-orbit adaptability is lost
Solution Approach 1:
The CMG array is designed with dynamic reconfiguration capability that enables in-orbit adaptation. The non-parallel rotation mechanisms allow the array to adjust its orientation after launch, compensating for mass property changes and failures that occur during the mission, thus gaining in-orbit adaptability without sacrificing initial deployment simplicity.
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 the reliability and capability of spacecraft momentum control by compensating for CMG failures and changes in mass properties, ensuring optimal momentum control space is maintained, even after initial setup or changes.
Implementation Method 1
A bearing is desirably provided between the CMG base and mount to facilitate rotation
Data Source
AI summary
Methods and apparatus are provided for reorienting control moment gyros (CMGs) to compensate for CMG failure or change in spacecraft (S/C) mass properties or mission. An improved CMG comprises a drive means for rotating the CMG around an axis not parallel to the CMG gimbal axis. Releasable clamps lock the CMG to the spacecraft except during CMG array reorientation. CMGs arrays are combined with attitude sensors, a command module, memory for storing data and programs, CMG drivers and sensors (preferably for each CMG axis), and a controller coupling these elements. The method comprises determining whether a CMG has failed or the S/C properties or mission changed, identifying the working CMGs of the array, determining a new array reorientation for improved spacecraft control, unlocking, reorienting and relocking the CMGs in the array and updating the S/C control parameters for the new array orientation.