CMG Gimbal Trajectory Optimization for Satellite Attitude Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing attitude control systems for artificial satellites using control moment gyros (CMGs) often prolong the period required for attitude change due to unnecessary prolongation of acceleration and deceleration intervals and heavy processing loads, which can decrease the efficiency of earth observation missions.
Innovation Solution
An attitude control device that sets boundary conditions for attitude angle and angular velocity, calculates gimbal angle trajectories with distinct acceleration, fixed, and deceleration intervals for each CMG, optimizing the driving capacity of each gimbal to minimize the attitude change period and reduce processing load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the gimbal angle trajectory uses a common fixed interval for all CMGs to simplify control, then the control system becomes easier to manage, but the acceleration and deceleration intervals are unnecessarily prolonged, leading to a longer attitude change period
Solution Approach 1:
The patent divides the gimbal angle trajectory into three distinct intervals: acceleration interval, fixed interval, and deceleration interval. By segmenting the trajectory and allowing each CMG to have customized interval durations based on its specific gimbal angle change requirements, the system avoids the unnecessary prolongation caused by using a common fixed interval for all CMGs, thus reducing the overall attitude change period while maintaining control manageability.
2Measurement precision
If iterative calculations based on Newton's laws are performed to calculate gimbal angles satisfying designated attitude and angular velocities, then the attitude control precision is improved, but the processing load on the satellite calculator increases significantly
Solution Approach 1:
The patent performs preliminary calculation of the gimbal angle trajectory on the ground before satellite launch. By pre-calculating the optimal trajectory that satisfies the desired attitude and angular velocity requirements, the complex iterative calculations are avoided during satellite operation, thereby reducing the processing load on the satellite calculator while maintaining attitude control precision.
3Reliability
If the acceleration and deceleration intervals are extended to accommodate all CMGs, then all gimbals can complete their angle changes, but the period until maximum attitude angular velocity is reached is prolonged
Solution Approach 1:
The patent implements dynamic interval adjustment where the durations of acceleration, fixed, and deceleration intervals are optimized based on the specific gimbal angle change requirements of each CMG. This dynamic approach allows each CMG to operate at its optimal speed profile, ensuring all gimbals complete their angle changes while minimizing the time to reach maximum attitude angular velocity, thus resolving the conflict between CMG coordination and attitude change speed.
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 allows for a shorter attitude change period and reduced processing load on the artificial satellite, enhancing the efficiency of earth observation missions by optimizing the gimbal angle trajectories and utilizing the driving capacity of each CMG effectively.
Implementation Method 1
a control moment gyro (CMG) mounted on an artificial satellite
Implementation Method 2
three or more control moment gyros (CMGs) for changing attitude of an artificial satellite
Data Source
AI summary
When calculating a gimbal angle trajectory that satisfies boundary conditions set by an attitude boundary condition setter 2131 of the ground station 21, a gimbal angle trajectory calculator 2132 calculates the gimbal angle trajectory that minimizes a period of an acceleration interval within a range that satisfies driving restrictions of a gimbal, based on a gimbal angle θ0i of a start time and a gimbal angle θci of a fixed interval of an attitude change. Also, the gimbal angle trajectory is calculated that minimizes a period of a deceleration interval within a range that satisfies the driving restrictions of the gimbal, based on the gimbal angle θci of the fixed interval and a gimbal angle θfi of a completion time of the attitude change. The obtained θ0i, θci, θfi and an attitude change period τ are transmitted to the artificial satellite as gimbal angle trajectory parameters, and the control moment gyros are controlled based on the gimbal angle trajectory parameters.