NMR Gyroscope Dynamic Magnetic Field Control for Inertial Navigation
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Solution Overview
Problem
Conventional NMR gyroscopes used in inertial navigation face challenges with spectral aliasing due to limited detection bandwidth, leading to oversized and power-hungry devices with degraded angular random walk parameters, which are not cost-effective or compact.
Innovation Solution
Integration of a MEMS gyroscope with the NMR gyroscope allows for dynamic adjustment of the static magnetic field amplitude, enhancing bandwidth and reducing spectral aliasing, while using multiple gases with distinct gyromagnetic ratios to optimize the magnetic field generation, thereby improving the angular random walk parameter and reducing device bulk and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the detection bandwidth of the NMR gyroscope is increased to avoid spectral aliasing, then measurement reliability is improved, but device size and power consumption increase
Solution Approach 1:
The patent applies dynamics by making the magnetic field amplitude adjustable rather than fixed. The generation element can modify the amplitude of the static magnetic field in real-time, allowing the detection bandwidth to be dynamically increased when needed to avoid spectral aliasing, while maintaining a compact device size by only increasing bandwidth temporarily when vibration frequencies require it.
Solution Approach 2:
The patent changes the parameter of magnetic field amplitude to resolve the contradiction. By adjusting the amplitude of the static magnetic field generated by the generation element, the detection bandwidth is modified to match the spectral range of rotational phenomena, thereby preventing spectral aliasing without requiring a permanently oversized device.
2Reliability
If the detection bandwidth of the NMR gyroscope is increased to avoid spectral aliasing, then measurement reliability is improved, but power consumption increases
Solution Approach 1:
The generation element dynamically adjusts the magnetic field amplitude based on the detected vibration frequencies. Power consumption increases only temporarily when the bandwidth needs to be expanded to capture high-frequency vibrations, rather than consuming high power continuously, thus resolving the contradiction between reliability and power usage.
Solution Approach 2:
The system periodically monitors the vibration spectrum and adjusts the magnetic field amplitude accordingly. The bandwidth is increased only during periods when high-frequency vibrations are detected, allowing the device to maintain low power consumption during normal operation while ensuring measurement reliability when needed.
3Reliability
If high amplitude static magnetic field is applied to increase bandwidth, then spectral aliasing is avoided, but angular random walk parameter degrades
Solution Approach 1:
The generation element dynamically adjusts the magnetic field amplitude to the minimum necessary level to avoid spectral aliasing. Rather than applying a continuously high amplitude field that degrades the angular random walk parameter, the system only increases the field strength temporarily when vibration frequencies exceed the current bandwidth, thereby maintaining measurement precision while avoiding spectral aliasing.
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 configuration enables reliable rotation measurement with reduced bulk and power consumption, achieving an optimal compromise between bandwidth and angular random walk, allowing for efficient and accurate inertial navigation.
Implementation Method 1
a generation element configured to generate a magnetic field directed along the sensitive axis
Implementation Method 2
nuclear spins of the different atoms in the detection gas are first oriented along a predetermined direction. In addition, a static magnetic field, directed along the sensing axis, is applied to the detection gas within the cell
Implementation Method 3
A set of oscillating magnetic fields (as many as there are sensing species in the detection gas) are also applied to the detection gas. Each of these magnetic fields oscillates successively over time at a frequency increasingly close to the natural frequency of oscillation of the corresponding sensing species
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a device for measuring rotation (2) including an NMR gyroscope (4) having a sensing axis, a computer (8), a generating member (18) configured to generate a magnetic field directed along the sensing axis, and a MEMS gyroscope (6) rigidly connected to the NMR gyroscope (4), the MEMS gyroscope (6) having a sensing axis aligned with the sensing axis of the NMR gyroscope (4), the MEMS gyroscope (6) being suitable for delivering a MEMS signal representing a rotation about the sensing axis, the computer (8) being configured to calculate, from an NMR signal output by the NMR gyroscope (4), information relating to a rotation about the sensing axis, and to analyse the MEMS signal over time in order to determine a current cut-off frequency, the computer (8) also being configured to control the generating member (18) in order to generate, over time, a magnetic field of which the amplitude is a function of the current cut-off frequency.