CMG Momentum Boundary Control for Agile Vehicle Reorientation
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Solution Overview
Problem
Existing spacecraft attitude control systems using control moment gyroscopes (CMGs) are limited by hardware constraints and singularities, which restrict the momentum that can be transferred and stored, leading to conservative momentum usage and reduced reorientation capabilities.
Innovation Solution
A method and system that adjust the torque command when the total angular momentum of the CMG array approaches a momentum boundary, by decreasing the input torque in the kinetic momentum direction, allowing the CMG array to operate within the momentum boundary while maintaining cross-axis control and preventing singularity and saturation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the CMG array operates at maximum momentum capability to enable faster reorientation, then the reorientation speed improves, but the system risks violating the momentum boundary and causing singularity or saturation
Solution Approach 1:
The control system continuously monitors the total angular momentum of the CMG array and dynamically adjusts the torque command based on the current momentum state. When the momentum approaches the boundary, the system automatically reduces the torque command in the kinetic momentum direction, creating a feedback loop that maintains operation within the safe momentum boundary while maximizing reorientation performance
Solution Approach 2:
The system transitions from static momentum limiting to dynamic momentum management. The momentum boundary is enforced dynamically by continuously adjusting the torque command based on real-time momentum measurements, allowing the system to operate at the maximum safe momentum level rather than being constrained by conservative fixed limits
2Reliability
If the system uses a self-imposed momentum limit confined by steering control law limits, then the system operates safely within boundaries, but the momentum capabilities are not maximized and reorientation is slower than possible
Solution Approach 1:
The system changes the momentum parameter dynamically by adjusting the torque command in the kinetic momentum direction based on the current state. Instead of using a fixed conservative momentum limit, the system continuously adapts the momentum utilization by modifying the torque command magnitude, allowing operation at the maximum safe momentum boundary
3Reliability
If the torque command is decreased in the kinetic momentum direction when approaching the momentum boundary, then the momentum boundary is maintained and singularity is prevented, but the reorientation torque is reduced
Solution Approach 1:
The system converts the potential harm of momentum boundary violation into a beneficial control strategy. By intentionally decreasing the torque command when approaching the boundary, the system prevents singularity and saturation while maintaining continuous stable operation. The 'reduction' in torque is actually a protective measure that prevents system failure and enables sustained operation
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 maximizes the momentum capabilities of the CMG array, enabling faster reorientation of the spacecraft by maintaining momentum within the boundary while ensuring stable operation.
Implementation Method 1
A control moment gyroscope (CMG) array comprising a plurality of CMGs onboard the agile vehicle and having a total angular momentum including a kinetic angular momentum component in a kinetic momentum direction
Implementation Method 2
using gyroscopes, known as control moment gyroscopes (CMGs), to control the attitude (or orientation) of a spacecraft, satellite, or another agile vehicle
Implementation Method 3
This change in angular momentum produces a reactionary torque which causes the spacecraft to rotate to the desired attitude or orientation
Data Source
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Figure 3~4
AI summary
Methods and systems are provided for reorienting an agile vehicle (114), such as a satellite or spacecraft, using a control moment gyroscope (CMG) array (110). The CMG array (110) comprises a plurality of CMGs onboard the agile vehicle (114). A method comprises obtaining an input torque command for reorienting the vehicle using the CMG array (110) and, when the angular momentum of the CMG array (110) violates or is approaching a momentum boundary (300) criterion, decreasing the input torque command in the kinetic momentum direction, resulting in a modified torque command, and operating the CMG array (110) using the modified torque command.