Spacecraft Formation Control Under Fixed-Thrust MPC Constraints
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Solution Overview
Problem
Spacecraft formation control is complicated by the need to maintain formation and separation distances while minimizing fuel consumption, constrained by limited communication bandwidth and computing resources, and maneuvering calculations are cumbersome due to thruster constraints.
Innovation Solution
A method employing a guidance and control algorithm using Model Predictive Control (MPC) with fixed thrust propulsion, iteratively calculating maneuver controls based on Relative Orbital Elements (ROE) to maintain spacecraft within a bounding box, allowing for autonomous and efficient maneuvering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional formation control methods are used with fixed thrust propulsion, then fuel consumption increases and maneuvering calculations become cumbersome, but maintaining formation stability and separation distances is required
Solution Approach 1:
The patent transforms the continuous control problem into a discrete parameter optimization problem by defining maneuver parameters (thruster selection, impulse magnitude, timing) that can be systematically evaluated. This allows the use of efficient search algorithms rather than complex continuous calculations, reducing computational burden while optimizing fuel consumption through parameter selection.
Solution Approach 2:
The patent implements a dynamic evaluation process where multiple candidate maneuvers are simulated and compared against formation constraints in real-time. The system dynamically selects the optimal maneuver from available options based on current formation state, allowing adaptive fuel-efficient control without requiring complex pre-calculated trajectories.
2Stability of the object's composition
If continuous monitoring and adjustment of spacecraft trajectories is performed to maintain formation, then formation stability is improved, but computing resources are consumed and communication bandwidth is required
Solution Approach 1:
The patent employs periodic evaluation of formation constraints at discrete intervals rather than continuous monitoring. By checking formation stability at specific update periods and only initiating maneuvers when constraints are violated, the system maintains formation stability while dramatically reducing computing resource consumption and communication bandwidth requirements.
Solution Approach 2:
The patent pre-defines formation constraints (bounding box parameters, separation distances) and evaluation criteria before operation. This allows the system to quickly evaluate whether maneuvers are needed by comparing current state against pre-established thresholds, reducing real-time computational requirements while maintaining stability.
3Loss of energy
If multiple thruster options are evaluated to find optimal maneuver controls, then fuel efficiency is improved, but calculation time and computational complexity increase
Solution Approach 1:
The patent segments the thruster evaluation process by categorizing thrusters into discrete options with defined characteristics (impulse magnitude, direction, fuel cost). This segmentation allows systematic evaluation of candidate maneuvers using structured algorithms rather than exhaustive continuous optimization, reducing calculation time while maintaining fuel efficiency through methodical comparison of segmented options.
Data Source
AI summary
For spacecraft control, a method iteratively measures a drifting spacecraft trajectory of a spacecraft relative to a bounding box, wherein the spacecraft has a fixed maximum thrust, a minimum thrust duration, a thrust duration that is an integer multiple of the minimum thrust duration, and a fixed update period. In response to the determining the spacecraft does not satisfy a trajectory condition, the method iteratively calculates maneuver controls wherein there are a number of guidance trajectories within the thruster duration. The method maneuvers the spacecraft along the guidance trajectories with the maneuver controls.