MEMS Gyroscope Phase and Gain Offset Compensation
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Solution Overview
Problem
MEMS sensors, such as accelerometers and gyroscopes, are prone to measurement errors due to external stresses and environmental changes like temperature, which can lead to instability and inconsistent performance throughout their lifecycle.
Innovation Solution
A method and system for estimating the variation of a MEMS sensor transfer function by imparting a drive signal and applying test signals to create a modified proof mass sense signal, allowing for the extraction and processing of in-phase and quadrature components to determine changes in demodulation phase or gain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MEMS sensors are used in commercial applications, then they can capture complex movements and determine orientation, but they are subject to manufacturing stresses and in-field external stresses that cause measurement errors
Solution Approach 1:
The patent applies preliminary calibration during manufacturing to establish baseline transfer function characteristics before the device is deployed. This preliminary action allows the system to later compensate for stress-induced deviations by comparing current measurements against the pre-established baseline, thereby maintaining measurement accuracy despite environmental stresses.
Solution Approach 2:
The patent implements a feedback mechanism where the system continuously monitors sensor output and compares it against expected values based on the transfer function. When deviations are detected due to stress, the system uses this feedback information to identify and correct measurement errors, ensuring reliable operation throughout the device lifecycle.
2Ease of manufacture
If standard manufacturing tolerances are applied, then production cost is reduced, but the MEMS chip experiences imparted forces as stress leading to performance variation
Solution Approach 1:
The patent enables the MEMS device to self-diagnose and self-correct for stress-induced performance variations through onboard calibration routines and transfer function monitoring. This self-service capability allows the device to maintain performance consistency without requiring tighter manufacturing tolerances or more expensive precision manufacturing processes.
Solution Approach 2:
The patent dynamically adjusts operational parameters based on detected stress conditions by monitoring changes in the transfer function characteristics. When stress is detected, the system modifies measurement parameters or applies correction factors to compensate for the stress-induced variations, thereby maintaining performance consistency despite standard manufacturing tolerances.
3Adaptability or versatility
If temperature changes occur, then environmental conditions vary, but stresses are imparted on the MEMS chip resulting in measurement errors
Solution Approach 1:
The patent incorporates temperature monitoring and transfer function tracking as feedback mechanisms. When temperature changes cause stress-induced deviations in sensor output, the system detects these changes through the feedback loop and applies appropriate compensation, thereby maintaining measurement precision across varying environmental conditions.
Solution Approach 2:
The patent implements dynamic compensation strategies where the system continuously adapts to changing temperature conditions by monitoring transfer function variations in real-time. Rather than using fixed compensation values, the system dynamically adjusts correction parameters based on current temperature and stress conditions, ensuring accurate measurements across the full operational temperature range.
4Duration of action of stationary object
If device aging occurs, then lifecycle progresses, but permanent stresses are induced on the mechanical structure causing sensitivity variations
Solution Approach 1:
The patent establishes a baseline transfer function characterization during manufacturing that serves as a reference for the entire device lifecycle. This preliminary action enables the system to detect and compensate for aging-induced performance drift by continuously comparing current measurements against the original baseline, thereby maintaining reliability over extended operational periods.
Solution Approach 2:
The patent implements long-term feedback monitoring where the system tracks transfer function variations throughout the device lifecycle. When aging-induced sensitivity variations are detected, the feedback mechanism triggers compensation routines that adjust measurement parameters or apply correction factors, ensuring performance stability even as the device ages.
Data Source
AI summary
An algorithm and architecture for sense transfer function estimation injects one or more test signals from a signal generator into a MEMS gyroscope to detect an output signal (e.g., proof mass output sense signal), including an in-phase (e.g., Coriolis) component and a quadrature component. The in-phase and quadrature components are encoded with reference signals to determine phase and/or gain variation and are processed via a variety of components (e.g., matrix rotation, digital gain, tones demodulator, transfer function errors estimation, etc.) to estimate a sense transfer function of the MEMS (e.g., Hs(fd)) and corresponding phase and/or gain offset of Hs(fd). The in-phase and quadrature components are also compensated for phase and/or gain offset by system components.