Spacecraft Attitude Control Using Star Sensors Without Gyros

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Solution Overview

Problem

Spacecraft autonomous pointing performance is hindered by the need for redundant inertial reference units (IRUs) due to the difficulty in identifying failed gyros, requiring ground team intervention which is time-consuming and impractical in critical situations.

Innovation Solution

A method and system that determines attitude and angular velocity using a minimal set of sensors, including star sensors, without relying on a spare IRU, by sensing star positions and implementing strategies to optimize attitude determination without angular velocity sensor information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spare IRU is included for redundancy, then reliability is improved, but device complexity and weight increase

Engineering Contradiction:

ImproveredundancyVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system performs self-diagnosis by autonomously detecting and identifying failed gyros through telemetry analysis and statistical evaluation, eliminating the need for ground team intervention and enabling the system to serve itself in maintaining operational reliability

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system pre-configures multiple operational modes and has pre-established criteria for gyro failure identification, allowing it to quickly switch to backup operational configurations without requiring real-time ground team decisions, thus maintaining reliability while reducing complexity

Inventive Principle:

Principle #10Preliminary action

2Reliability

If ground team intervention is used to identify failed gyros, then reliability is maintained, but loss of time increases

Engineering Contradiction:

ImprovereliabilityVSAvoidreconfiguration time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The system autonomously identifies failed gyros by analyzing telemetry data and computing statistical measures, eliminating the time-consuming process of ground team manual identification and enabling immediate reconfiguration

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system continuously monitors gyro performance through telemetry and uses feedback from statistical analysis to automatically detect failures, enabling real-time identification and immediate switching to backup configurations without ground team delay

Inventive Principle:

Principle #23Feedback

3Reliability

If internally redundant IRU with four gyros is used, then reliability is improved, but the system still cannot quickly identify which gyro failed

Engineering Contradiction:

ImproveredundancyVSAvoidfailure identification difficulty

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The system replaces manual ground team analysis with automated computational methods, using processors to calculate statistical measures and automatically identify failed gyros based on telemetry data patterns

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-diagnosis by autonomously analyzing its own telemetry data and identifying failed components through statistical evaluation, eliminating the need for external ground team intervention

Inventive Principle:

Principle #25Self-service

4Reliability

If a separate backup IRU is required, then reliability is improved, but weight and launch cost increase

Engineering Contradiction:

Improvebackup redundancyVSAvoidvehicle weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

The system autonomously manages its own redundancy by automatically detecting failures and switching to backup operational modes, eliminating the need for separate physical backup IRUs and reducing vehicle weight

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The four-gyro system is designed to perform multiple functions: normal operation with all four gyros, and degraded operation with any three gyros, making the same hardware universally capable of handling both nominal and failure conditions without requiring separate backup equipment

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

Enables autonomous and efficient control of spacecraft attitude and angular velocity, eliminating the need for a redundant IRU and reducing the time required for reconfiguration, thus improving pointing performance in real-time critical situations.

Implementation Method 1

sensing a position of each of a plurality of stars relative to the vehicle

Methodology Applied

Scientific EffectStellar sensing:

Data Source

PatentUS8265804B1Method and system for controlling a vehicle

Publication Date: 2012.09.11 THE BOEING CO

AI summary

A method for controlling a vehicle may include sensing a position of each of a plurality of stars relative to the vehicle. The method may also include determining an attitude of the vehicle using the sensed positions of the plurality of stars, and the attitude may be determined either with or without using information from a gyro or sensor for measuring angular velocity. The method may additionally include implementing a set of strategies to optimize determination of the attitude of the vehicle when using only the sensed positions of the plurality of stars, without information from the sensor for measuring angular velocity. The method may further include controlling the vehicle based on the determined attitude of the vehicle.