Multi-axis Atomic Inertial Sensor Error Correction
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Solution Overview
Problem
Cold atom inertial sensors face challenges in achieving desirable update rates and sensitivity while minimizing size, weight, and power, with a minimum volume requirement for six-degree-of-freedom atomic inertial measurement units (IMUs) being less than 20 cm^3, and existing sensors suffer from bias and scale factor drift issues.
Innovation Solution
Implementing multi-axis atomic inertial sensors with an optical multiplexer that sequentially changes sense axes using switching optics to correct errors in conventional inertial sensors, combining with MEMS inertial sensors for continuous output and error correction, and utilizing an optical gimbal sensor to maintain orientation and adjust sensitivity dynamically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the atomic inertial sensor size is reduced to minimize size, weight, and power, then the sensor volume decreases, but sensitivity deteriorates
Solution Approach 1:
The patent merges multiple atomic inertial sensors into a single integrated unit that measures multiple axes (three acceleration axes and three rotation axes) simultaneously. This consolidation allows the system to achieve six-degree-of-freedom measurement capability while maintaining a compact form factor, resolving the contradiction between miniaturization and sensitivity by distributing sensing functions across multiple coordinated sensors rather than requiring one large sensor for each axis
Solution Approach 2:
The atomic inertial sensor is designed with multi-functionality to perform both acceleration measurement and rotation measurement simultaneously across multiple axes. The sensor uses a common atom source and interferometer structure that can be configured to measure different physical quantities depending on the laser beam geometry and detection scheme, thereby achieving high sensitivity across multiple parameters within a single compact device
2Measurement precision
If cold atom interferometers are used to provide accurate inertial measurements, then measurement precision improves, but update rate deteriorates
Solution Approach 1:
The patent employs preliminary action by using a cold atom interferometer to establish accurate bias and scale factor calibration before the actual measurement period. The atomic sensor performs initial characterization and error correction of the MEMS sensor, allowing the MEMS sensor to operate at high update rates with pre-corrected parameters, thus resolving the contradiction between measurement precision and update rate
Solution Approach 2:
The system implements feedback by continuously using the atomic inertial sensor to correct bias and scale factor drift in the MEMS inertial sensor. The atomic sensor's high-precision measurements provide feedback signals that are used to adjust and recalibrate the MEMS sensor parameters in real-time, maintaining both high accuracy and high update rate through iterative correction
3Productivity
If MEMS inertial sensors are used as flywheel to provide continuous output, then update rate improves, but reliability deteriorates due to bias and scale factor drift
Solution Approach 1:
The atomic inertial sensor serves as a reference standard that provides feedback to correct the bias and scale factor drift of the MEMS sensor. By continuously comparing the atomic sensor measurements with the MEMS sensor output and applying correction algorithms, the system maintains high reliability while preserving the high update rate capability of the MEMS sensor
Solution Approach 2:
The patent replaces the mechanical limitation of the MEMS sensor (prone to drift) with the quantum mechanical basis of the atomic interferometer (fundamentally stable). The atomic sensor's immunity to mechanical wear and environmental drift provides a stable reference that corrects the MEMS sensor's biases, thereby improving reliability without sacrificing update rate
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 reduces the duty cycle of atomic sensors, enhances sensitivity and reliability by minimizing moving parts, and achieves low size, weight, and power consumption by extracting six degrees of inertial freedom from a single pair of atomic sensors, effectively correcting bias and scale factor errors in conventional sensors.
Implementation Method 1
an optical multiplexer operatively coupled to the multi-axis atomic inertial sensors. The optical multiplexer includes a plurality of optical switches configured to sequentially direct light along different axes of the first and second multi-axis atomic inertial sensors
Implementation Method 2
Cold atom interferometers are the basis for a newer class of inertial sensors. Analogous to the function of a fiber optic or ring laser gyroscope, inertial forces induce phase shifts in the quantum mechanical wave function of atoms traversing a loop in a cold atom interferometer
Implementation Method 3
utilizing an optical gimbal sensor to maintain orientation and adjust sensitivity dynamically
Data Source
Figure 1
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Figure 3A~3B
AI summary
An inertial sensing system comprises a first multi-axis atomic inertial sensor, a second multi-axis atomic inertial sensor, and an optical multiplexer optically coupled to the first and second multi-axis atomic inertial sensors. The optical multiplexer is configured to sequentially direct light along different axes of the first and second multi-axis atomic inertial sensors. A plurality of micro-electrical-mechanical systems (MEMS) inertial sensors is in operative communication with the first and second multi-axis atomic inertial sensors. Output signals from the first and second multi-axis atomic inertial sensors aid in correcting errors produced by the MEMS inertial sensors by sequentially updating output signals from the MEMS inertial sensors.