NMR Gyroscope Mechanization Using Three Isotopes

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Solution Overview

Problem

Nuclear magnetic resonance (NMR) gyroscopes face challenges in accurately measuring rotation angles due to dependence on frequency references and stability, which can be unreliable and resource-intensive, especially when measuring precession frequencies rather than angles.

Innovation Solution

The NMR gyroscope system employs three gyromagnetic isotopes that precess in response to a uniform magnetic field, with an angular rotation sensor measuring precession angles independently of time duration and local magnetic fields, allowing for the calculation of rotation angles without relying on frequency references, using a mechanization equation that cancels out variables like measurement period and magnetic field magnitudes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If frequency references are used to measure precession frequencies, then measurement precision can be achieved, but reliability deteriorates due to frequency stability issues

Engineering Contradiction:
Improverotation angle measurement precisionVSAvoidfrequency reference stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The patent replaces the frequency-based measurement system with an angle-based measurement system. Instead of measuring precession frequencies and relying on frequency references, the system directly measures precession angles using an angular rotation sensor. This substitution eliminates the reliability issues associated with frequency reference stability while maintaining measurement precision through direct angle measurement.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the measurement parameter from frequency to angle. By measuring precession angles rather than precession frequencies, the system transforms the measurement domain. This parameter change allows the system to avoid the reliability problems of frequency references while achieving the same measurement objective of determining rotation angles.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If precession frequencies are measured, then rotation information can be obtained, but device complexity increases due to frequency reference requirements

Engineering Contradiction:
Improverotation measurement capabilityVSAvoidfrequency reference system
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent simplifies the system by replacing the complex frequency reference system with a simpler angle measurement approach. The angular rotation sensor directly measures precession angles without requiring stable frequency references, thereby reducing device complexity while maintaining the capability to obtain rotation information.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and eliminates the frequency reference component from the system. By directly measuring angles rather than frequencies, the system removes the need for frequency references and associated stability mechanisms, thereby reducing overall device complexity while preserving rotation measurement functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

3Speed

If frequency-based measurement is used, then rotation rate can be determined, but loss of time increases due to measurement period dependencies

Engineering Contradiction:
Improverotation rate determinationVSAvoidmeasurement period
Core Design Contradiction:
SpeedVSLoss of time

Solution Approach 1:

The patent changes the measurement parameter from frequency to angle, which fundamentally alters the measurement approach. By measuring precession angles directly, the system eliminates time-dependent measurements and associated losses. The angle measurement approach provides rotation information without being constrained by measurement period durations or time-based frequency references.

Inventive Principle:
Principle #35Parameter changes

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 enables accurate and efficient measurement of rotation angles, reducing reliance on frequency stability and processing resources, and standardizing measurement periods across isotopes, thus providing a robust and precise method for determining rotation angles.

Implementation Method 1

An NMR gyroscope operates on the principle of sensing inertial angular rotation rate or angle about a sensitive axis based on a shift in the Larmor precession frequency or phase of one or two isotopes that possess nuclear magnetic moments

Methodology Applied
Scientific EffectLarmor precession: Magnetic Field

Implementation Method 2

The gyro cell can contain one or more alkali metal vapors, such as Rubidium, together with one or two gyromagnetic isotopes that are caused to precess in response to a magnetic field

Methodology Applied
Scientific EffectOptical pumping:

Data Source

PatentEP2282167B8Nuclear magnetic resonance gyroscope mechanization
Publication Date: 2018.07.18 NORTHROP GRUMMAN SYSTEMS CORP

AI summary

One embodiment of the invention includes a nuclear magnetic resonance (NMR) gyroscope system. The system includes a gyro cell that is sealed to enclose an alkali metal vapor, a first gyromagnetic isotope, a second gyromagnetic isotope, and a third gyromagnetic isotope. The system also includes a magnetic field generator configured to generate a substantially uniform magnetic field that is provided through the gyro cell to cause the first, second, and third gyromagnetic isotopes to precess. The system further includes an angular rotation sensor configured to measure a rotation angle about a sensitive axis of the NMR gyroscope system based on measured precession angles of the first, second, and third gyromagnetic isotopes.