Spacecraft Exclusion Zone Guidance Method
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Solution Overview
Problem
Existing methods for guiding a spacecraft or similar vehicles to avoid pointing their sensing instruments within a prohibited exclusion zone, such as towards the sun, often result in high commanded rates and accelerations that exceed dynamic limits, leading to inefficient exclusion zone avoidance and prolonged compromised tracking.
Innovation Solution
A method that modifies attitude commands in real-time using current measurements to steer the sensing instrument's boresight around the exclusion zone while keeping within the vehicle's dynamic limits and minimizing the duration of compromised tracking, without relying on complex predictive models or propagation of future positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the boresight is prevented from pointing into the exclusion zone by modifying attitude commands, then the sensing instrument is protected from damage, but the tracking duration is compromised and extended
Solution Approach 1:
The method initiates avoidance maneuvers before the boresight would actually enter the exclusion zone by detecting when the current pointing trajectory will intersect the exclusion zone. This preliminary detection and early initiation of avoidance allows the system to protect the sensing instrument while minimizing tracking compromise by only deviating when necessary.
Solution Approach 2:
The system dynamically adjusts the avoidance maneuver based on real-time measurements of the current pointing trajectory and exclusion zone geometry. The attitude commands are modified adaptively rather than using fixed conservative margins, allowing the boresight to maintain optimal pointing for as long as possible while still avoiding the exclusion zone when needed.
2Reliability
If the boresight avoids the exclusion zone by tracing the boundary, then the sensing instrument is protected, but high commanded rates and accelerations exceed the vehicle's dynamic limits
Solution Approach 1:
By detecting potential intersection with the exclusion zone in advance, the system can initiate smooth avoidance maneuvers that build up rates and accelerations gradually within dynamic limits, rather than requiring abrupt boundary-tracing maneuvers that would exceed vehicle capabilities.
Solution Approach 2:
The system uses real-time feedback from the current pointing trajectory and exclusion zone geometry to continuously adjust avoidance commands. This feedback mechanism ensures that maneuvers remain within dynamic limits by adapting to the actual vehicle state and trajectory, preventing excessive rates and accelerations.
3Reliability
If a conservative avoidance strategy is used to ensure exclusion zone avoidance for all possible approach rates, then the sensing instrument is protected, but the tracking compromise duration is unnecessarily extended
Solution Approach 1:
The system transitions from static conservative margins to dynamic adaptive avoidance that responds to actual real-time conditions. By continuously measuring the current pointing trajectory and calculating actual intersection risk, the system applies avoidance only when and where needed, rather than using fixed conservative buffers that extend tracking compromise unnecessarily.
Solution Approach 2:
The avoidance strategy changes parameters dynamically based on measured conditions - the degree and timing of avoidance maneuvers are adjusted according to the actual approach rate and trajectory, rather than applying uniform conservative avoidance for all scenarios. This allows optimal balance between protection and tracking continuity.
Data Source
AI summary
Systems and methods for are adapted for automatic implementation of exclusion zone avoidance for target-tracking vehicles, such as spacecraft. The systems and methods are configured to monitor pointing commands (commanded attitude and angular rates) generated for target tracking, and modify these commands as necessary to avoid pointing a boresight into an exclusion zone.