Non-redundant SGCMG Manipulation Method for Singularity Avoidance
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Solution Overview
Problem
Conventional methods for spacecraft attitude control using a cluster of control moment gyroscopes (CMGs) are inadequate for non-redundant systems, as they cannot avoid singularity configurations, leading to potential loss of three-axis attitude maneuver ability and instability when gimbal angles fail to return to their initial state.
Innovation Solution
A manipulation method for a non-redundant cluster of single-gimbal control moment gyroscopes (SGCMGs) is developed, which determines a nominal gimbal angle vector, calculates the Jacobian matrix, and adjusts gimbal angular velocity commands based on a multi-objective optimization cost function to ensure singularity avoidance and stable attitude control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a redundant configuration with at least four SGCMGs is adopted to avoid singularity through gimbal-reconfiguring, then singularity avoidance is improved, but system complexity increases and reliability decreases when CMG failures occur
Solution Approach 1:
The patent pre-calculates and stores nominal gimbal angle vectors and singularity-avoidance parameters before actual operation. When CMG failure occurs, the system immediately switches to pre-computed non-redundant manipulation equations, avoiding the need for complex real-time gimbal reconfiguration and ensuring rapid response to failures
Solution Approach 2:
The patent extracts and separates the singularity-avoidance function from the primary attitude control function. By independently calculating and storing singularity-avoidance parameters alongside nominal gimbal angles, the system can independently handle singularity avoidance without affecting the main control algorithm, thus simplifying the overall system response to failures
2Ease of operation
If conventional manipulation methods based on redundant CMG systems are used in non-redundant systems, then three-axis attitude control is maintained, but singularity avoidance capability is lost
Solution Approach 1:
The patent changes the fundamental parameters of the manipulation equations from redundant to non-redundant configuration. By adapting the manipulation equations to match the actual number of working CMGs (three instead of four or more), the system maintains full three-axis attitude control capability while inherently avoiding singularities through the modified mathematical model
Solution Approach 2:
The patent implements dynamic adaptation of the manipulation equations based on the actual number of functional CMGs. The system automatically switches between different manipulation equation sets depending on whether the system is in redundant or non-redundant mode, ensuring optimal performance and singularity avoidance for each configuration
3Productivity
If gimbal angles are not returned to initial state after attitude maneuver, then attitude control is simplified, but unexpected states near singularity may cause loss of attitude control
Solution Approach 1:
The patent incorporates real-time feedback monitoring of gimbal angles and singularity measures. When gimbal angles approach expected values that could lead to singularity, the system automatically adjusts the manipulation equations or modifies the maneuver trajectory to maintain safe operating distances, thus preventing loss of attitude control while allowing fast maneuvers
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 method effectively reconciles the contradiction between singularity avoidance and three-axis attitude control, ensuring high-performance attitude maneuver even in non-redundant systems by optimizing gimbal angle deviations and torque output, thereby preventing spacecraft attitude loss.
Implementation Method 1
a cluster of control moment gyroscopes (CMGs)... each having the same angular momentum amplitude
Implementation Method 2
The total angular momentum H of the n SGCMGs... the variable A and B represent a 3×n dimensional coefficient matrices related to installation orientations of gimbal axes
Data Source
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AI summary
A manipulation method suitable for a non-redundant SGCMG group. The method comprises the steps: 1) determining, according to configurations and synthetic angular momentums of n SGCMGs, nominal frame angle vector of the configurations of n SGCMGs, wherein n ≥ 3; 2) determining, according to a frame angle of each SGCMG, Jacob of a motion equation of the frame angle and the deviation of the frame angle from a nominal value; and 3) determining, according to the Jacob and the deviation of the frame angle from the nominal value that are determined in step 2), a frame angular velocity instruction of the SGCMG. According to the method of the present invention, the distance that a frame angle is deviated from the nominal value, a frame angle instruction amplitude value, and a torque output deviation are taken into consideration, such that the capability of avoiding singularities in attitude maneuvering and returning to a frame nominal position after maneuvering is achieved, the contradiction between singularity avoidance and an attitude control torque of a CMG frame is resolved, and the realization of high performance of maneuvering along any attitude can be ensured.