MEMS Gyroscope Bias Reduction via Calibration Injection
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Solution Overview
Problem
Microelectromechanical (MEMS) Coriolis vibratory gyroscopes (CVGs) face challenges in accurately determining angular velocity due to deflection bias, which introduces error in measurements and cannot be effectively calibrated online without disrupting system operations.
Innovation Solution
A gyroscope subsystem that includes a MEMS CVG, a calibration assembly, and a bias-reducing circuit, which injects a calibration angular velocity and uses in-phase and quadrature demodulation to minimize the deflection bias component in the determined angular velocity, allowing for real-time bias reduction without requiring the system to be offline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional calibration methods are used to reduce deflection bias, then measurement precision improves, but system operation is disrupted and time is lost
Solution Approach 1:
The calibration assembly pre-applies known angular velocity inputs to the gyroscope before actual measurement, establishing a baseline for bias correction. This preliminary calibration action enables subsequent real-time compensation without requiring system shutdown, thus improving measurement precision while minimizing operational disruption
Solution Approach 2:
The system performs calibration and measurement operations continuously without interruption. The calibration assembly can apply test inputs while the gyroscope simultaneously performs its measurement function, and the bias-reducing circuit processes both calibration and measurement data in real-time, maintaining continuous useful action and eliminating downtime
2Productivity
If deflection bias is not corrected, then system operation remains continuous, but measurement precision deteriorates
Solution Approach 1:
The bias-reducing circuit receives feedback from the calibration assembly about the gyroscope's deflection bias and continuously adjusts the measurement output to compensate for this bias. This feedback mechanism enables real-time correction of measurement errors while maintaining continuous operation, simultaneously achieving high productivity and measurement precision
Solution Approach 2:
The bias-reducing circuit acts as an intermediary between the gyroscope sensor and the measurement output. It processes the raw gyroscope signal, removes the deflection bias component, and produces corrected measurements, thereby enabling continuous operation with high precision through this intermediary correction layer
3Measurement precision
If complex calibration procedures are implemented, then measurement precision improves, but device complexity increases
Solution Approach 1:
The gyroscope system performs its own calibration using the integrated calibration assembly and bias-reducing circuit, eliminating the need for external complex calibration equipment. The system self-diagnoses and self-corrects its deflection bias through automated procedures, improving measurement precision while keeping device complexity manageable through self-service operation
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
The solution significantly reduces the deflection bias component in the measured angular velocity, enhancing the accuracy and reliability of angular velocity calculations while maintaining continuous system operation.
Implementation Method 1
the MEMS CVG 10 is configured to generate a signal from which the angular velocity {right arrow over (Ω)}(t) can be derived by making use of the Coriolis acceleration
Data Source
AI summary
An embodiment of a gyroscope subsystem that is configured to reduce, or to eliminate, the effect of bias includes a gyroscope assembly, a calibration assembly, a determining circuit, and a bias-reducing circuit. The gyroscope assembly is configured to generate a gyroscope signal in response to a calibration angular velocity and another angular velocity about a sense axis, and the calibration assembly is configured to generate, about the sense axis, the calibration angular velocity. The determining circuit is configured to determine the other angular velocity in response to the gyroscope signal, and the bias-reducing circuit is configured to reduce a bias component of the determined other angular velocity in response to the gyroscope signal. For example, such a gyroscope subsystem can yield a value of an angular velocity having a bias component that is significantly less than the bias component of a value yielded by a conventional gyroscope subsystem.