MEMS Gyroscope Thermal Drift Compensation via Calibration Actuator
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Solution Overview
Problem
Microelectromechanical gyroscopes face challenges in stabilizing the zero rate output due to quadrature errors, which are exacerbated by temperature variations and manufacturing defects, leading to residual drifts that current compensation methods fail to adequately address.
Innovation Solution
The proposed solution involves a microelectromechanical gyroscope design that includes a support structure, a sensing mass, a calibration structure, and a calibration actuator. The calibration structure is movable relative to the sensing mass, allowing for variations in the gap width between them, which are controlled by the calibration actuator to modulate the quality factor and compensate for thermal drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If individual calibration is performed to reduce zero rate output drift, then measurement precision is improved, but productivity deteriorates due to extremely long calibration time and high cost
Solution Approach 1:
The patent applies preliminary action by performing calibration during the manufacturing process before the gyroscope is delivered to the customer. A calibration structure is integrated into the device, allowing calibration to be completed in a few seconds during production, eliminating the need for time-consuming field calibration while achieving individualized calibration for each device
Solution Approach 2:
The patent introduces a calibration structure as an intermediary element that enables rapid calibration. This calibration structure acts as a mediator between the sensing mass and the external calibration system, allowing quick adjustment of the quadrature error without requiring complex calibration procedures
2Measurement precision
If closed-loop dynamic compensation is implemented to adapt to actual conditions, then measurement precision is improved, but device complexity increases due to complex compensation circuits
Solution Approach 1:
The patent extracts the calibration function from complex closed-loop compensation circuits and implements it through a dedicated calibration structure. This separates the calibration function from the operational sensing function, allowing simple structure to handle calibration while maintaining measurement precision without requiring complex dynamic compensation circuits
Solution Approach 2:
The calibration structure enables the gyroscope to perform self-calibration during manufacturing. The device calibrates itself automatically through the integrated calibration structure without requiring external complex compensation systems, reducing device complexity while maintaining precision
3Device complexity
If family compensation is applied to reduce cost, then device complexity is reduced, but measurement precision deteriorates due to residual drift from non-individualized correction
Solution Approach 1:
The patent performs individual calibration during manufacturing before the device leaves the factory. This preliminary calibration ensures each device is individually optimized, eliminating the need for complex family-based statistical compensation while achieving high precision with simple post-manufacturing devices
Solution Approach 2:
The calibration structure creates a standardized calibration mechanism that can be replicated across all devices. This allows each device to be individually calibrated using the same simple structure, achieving individualized precision without complex systems while maintaining manufacturing efficiency
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 effectively reduces the temperature-induced drift of the zero rate output by dynamically adjusting the gap width between the sensing mass and the calibration structure, thereby improving the stability and accuracy of the gyroscope's output.
Implementation Method 1
compensating an output thermal drift in a microelectromechanical gyroscope
Implementation Method 2
variations in the average width of the gap cause a modulation of a quality factor of the sensing mass
Data Source
AI summary
A microelectromechanical gyroscope includes: the support structure; a sensing mass, coupled to the support structure with degrees of freedom along a driving direction and a sensing direction perpendicular to each other; and a calibration structure facing the sensing mass and separated from the sensing mass by a gap having an average width, the calibration structure being movable with respect to the sensing mass so that displacements of the calibration structure cause variations in the average width of the gap. A calibration actuator controls a relative position of the calibration structure with respect to the sensing mass and the average width of the gap.