Spacecraft Torque Control Without Ephemeris Data

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Solution Overview

Problem

Spacecraft control systems face challenges in calculating resultant torque imparted by magnetic torque rods when ephemeris information is inaccessible, such as during launch vehicle separation or processor resets, as they typically rely on ephemeris knowledge to determine the Earth's magnetic field.

Innovation Solution

A control system that calculates the resultant torque based on the dipole moment of magnetic torque rods and an average magnetic field estimate of the celestial body, allowing torque exertion without requiring ephemeris information, utilizing a predictable and fixed magnetic field direction around the spacecraft's orbit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the control system uses ephemeris information to calculate the Earth's magnetic field for determining resultant torque, then the measurement precision of the magnetic field is improved, but the reliability of the system deteriorates when ephemeris information becomes inaccessible during contingency scenarios

Engineering Contradiction:

Improvemagnetic field calculation precisionVSAvoidsystem reliability during contingency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the parameter used for magnetic field calculation from position-dependent ephemeris data to a constant dipole moment model. This allows the system to calculate magnetic field estimates without requiring precise spacecraft position information, maintaining operational capability during contingency scenarios when ephemeris data is unavailable.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a simplified average magnetic field estimate model that does not require complex ephemeris data. This approach sacrifices some precision but ensures the system can continue operating during contingency scenarios, effectively using a simpler, more robust calculation method that is always available.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Measurement precision

If the control system requires ephemeris information for torque calculation, then the measurement precision is improved, but the ease of operation deteriorates during launch vehicle separation or processor reset scenarios

Engineering Contradiction:

Improvetorque calculation precisionVSAvoidoperational ease during contingency

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent extracts the dependency on ephemeris information from the torque calculation process by using a dipole moment model with average magnetic field estimates. This allows the control system to determine resultant torque without requiring access to ephemeris data, simplifying operation during contingency scenarios.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If the control system uses a dipole moment model with average magnetic field estimate, then the reliability during contingency scenarios is improved, but the measurement precision of the magnetic field deteriorates

Engineering Contradiction:

Improvesystem reliability without ephemerisVSAvoidmagnetic field estimate precision

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent uses average magnetic field estimates rather than precise location-specific field values. This partial approach provides sufficient accuracy for momentum management purposes while ensuring the system can operate reliably during contingency scenarios when precise ephemeris data is unavailable.

Inventive Principle:

Principle #16Partial or excessive action

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 continuous momentum management for spacecraft by calculating and applying torque independently of ephemeris knowledge, ensuring operational stability during contingency scenarios like launch vehicle separation or processor resets.

Implementation Method 1

Magnetic torque rods may carry electric current having an associated magnetic field that interacts with the Earth's local magnetic field, which produces a resultant torque imparted upon a spacecraft

Methodology Applied

Scientific EffectElectromagnetic field interaction: Lorentz Force

Implementation Method 2

Magnetic torque rods may carry electric current having an associated magnetic field

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11174047B2Spacecraft control system for determining reaction torque

Publication Date: 2021.11.16 THE BOEING CO

AI summary

A control system for a spacecraft for determining a resultant torque that is exerted upon a spacecraft by one or more magnetic torque rods is disclosed. The spacecraft is configured to revolve around a celestial body in an orbit. A magnetic field of the celestial body is predictable, and a direction of the magnetic field located around the orbit is fixed. The control system includes the one or more magnetic torque rods, one or more processors in electronic communication with the one or more magnetic torque rods, and a memory coupled to the one or more processors. The memory stores data into a database and program code that, when executed by the one or more processors, causes the control system to instruct the one or more magnetic torque rods to exert the resultant torque upon the spacecraft.