CMG Singularity Escape via Virtual Array Rotation
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Solution Overview
Problem
Control moment gyroscopes (CMGs) face challenges in singularity escape and avoidance, leading to loss of control and instability in satellite attitude due to computational singularities, which existing methods address inadequately with slow performance, additional actuator requirements, and torque disturbances.
Innovation Solution
The method involves calculating a Jacobian matrix, determining closeness to singularity, and recalculating the Jacobian to generate a virtual misalignment, allowing the CMG array to rotate and avoid singularities, thereby maintaining control and utilizing the momentum envelope beyond singularities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external actuators are added to escape singularities, then control reliability is improved, but device complexity and response speed deteriorate
Solution Approach 1:
The patent introduces a virtual misalignment parameter as an intermediary that mediates between the CMG array configuration and singularity avoidance. By adjusting this virtual parameter, the system can escape singularities without adding physical actuators, thus maintaining reliability while avoiding increased device complexity
Solution Approach 2:
The patent changes the misalignment parameter of the CMG array to escape singularities. By dynamically adjusting this parameter, the system maintains control reliability without adding external actuators, thereby avoiding increased device complexity and maintaining fast response speeds
2Reliability
If mathematical augmentation of control law is used, then singularity avoidance capability is improved, but computational intensity and torque disturbance worsen
Solution Approach 1:
The patent performs preliminary action by pre-calculating the virtual misalignment parameter and its relationship to singularity conditions. This allows the system to quickly determine escape directions without intensive real-time computation, reducing computational intensity while maintaining effective singularity avoidance
Solution Approach 2:
The patent extracts the essential singularity avoidance function from complex mathematical augmentation and implements it through simple virtual misalignment parameter adjustment. This extraction reduces computational intensity while maintaining the capability to avoid singularities and minimize torque disturbance
3Productivity
If CMG array operates near singularity, then momentum envelope utilization is improved, but control stability deteriorates
Solution Approach 1:
The patent implements feedback by continuously monitoring the CMG array's proximity to singularities and automatically adjusting the virtual misalignment parameter when singularity conditions are detected. This feedback mechanism allows the system to utilize the momentum envelope near singularities while maintaining control stability through automatic correction
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 effectively prevents loss of control by enabling the CMG array to escape singularities and maintain attitude control with improved reliability and reduced computational intensity, ensuring continuous satellite orientation.
Implementation Method 1
A control moment gyroscope (CMG) maintains and adjusts the attitude of a satellite. A CMG usually consists of a spinning rotor and multiple motorized gimbals that tilt the rotor's angular momentum.
Implementation Method 2
When the rotor is displaced about a gimbal axis, the angular momentum changes and causes a gyroscopic torque that rotates the satellite.
Data Source
AI summary
Techniques for providing singularity escape and avoidance are disclosed. In one embodiment, a method for providing control moment gyroscope (CMG) attitude control singularity escape includes calculating a Jacobian A of a set of control equations, calculating a measure of closeness to a singularity, and comparing the calculated closeness to a threshold value, when the calculated closeness is less than or equal to the threshold value, recalculating the Jacobian A. Recalculating may include determining a new direction of virtual misalignment of β and γ, recalculating the Jacobian inputting the new direction of the virtual misalignment, recalculating the measure of closeness to a singularity, and comparing the measure of closeness to the threshold value. Further, the method may include calculating a gimbal rate command if the of closeness is greater than the threshold value and generating a torque from the gimbal rate command to control the attitude of a satellite.