MEMS Sensor Detecting Rotation via Coriolis Frequency Doubling
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Solution Overview
Problem
Existing MEMS sensors require multiple specialized and costly devices to detect accelerations and rotational movements, which are complex to manufacture and prone to vulnerability.
Innovation Solution
A MEMS sensor design that uses a single device with moveable driving and sensing masses on a substrate, where the same sensing elements detect accelerations and rotations by distinguishing between different frequency responses to external accelerations and rotations, allowing for the detection of three acceleration and three rotation axes with minimal moving parts and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple specialized sensors are used to detect accelerations and rotational movements, then detection accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines acceleration sensing and rotation rate sensing into a single MEMS sensor device. The sensing mass and connection springs serve dual purposes: detecting linear acceleration through direct deflection and detecting rotational movement through Coriolis force-induced deflection. This merging eliminates the need for separate specialized sensors while maintaining detection accuracy for both types of motion.
Solution Approach 2:
The sensing elements in the patent are designed to perform multiple functions. The same sensing mass and connection springs that detect acceleration also detect rotational movements when subjected to Coriolis forces. The drive elements drive the sensing mass for both acceleration detection and rotation detection, making the system universal and multi-functional rather than requiring specialized components for each sensing modality.
2Measurement precision
If multiple specialized sensors are used to detect accelerations and rotational movements, then detection accuracy is improved, but manufacturing cost increases
Solution Approach 1:
The patent combines acceleration sensing and rotation rate sensing into a single MEMS sensor device. The sensing mass and connection springs serve dual purposes: detecting linear acceleration through direct deflection and detecting rotational movement through Coriolis force-induced deflection. This merging eliminates the need for separate specialized sensors while maintaining detection accuracy for both types of motion.
3Measurement precision
If specialized sensors are used for accelerations and rotations, then detection capability is improved, but vulnerability increases
Solution Approach 1:
The patent combines acceleration sensing and rotation rate sensing into a single MEMS sensor device. The sensing mass and connection springs serve dual purposes: detecting linear acceleration through direct deflection and detecting rotational movement through Coriolis force-induced deflection. This merging eliminates the need for separate specialized sensors while maintaining detection accuracy for both types of motion.
4Device complexity
If the same sensing elements are used for both acceleration and rotation detection, then device complexity is reduced, but distinguishing between acceleration and rotation becomes difficult
Solution Approach 1:
The patent employs periodic driving of the sensing mass at a specific driving frequency. When linear acceleration occurs, the sensing mass deflects at the driving frequency. When rotational movement occurs, Coriolis forces cause the sensing mass to deflect at twice the driving frequency (2ω). This frequency multiplication creates distinct periodic signatures that allow the evaluation unit to easily distinguish between acceleration and rotation events despite using the same sensing elements.
Solution Approach 2:
The patent changes the frequency parameter of the sensing mass response based on the type of motion detected. Linear acceleration produces responses at the fundamental driving frequency, while rotational movement produces responses at double the driving frequency. This parameter change (frequency doubling for rotation) provides a clear distinction mechanism that simplifies the evaluation process while maintaining device simplicity.
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 enables accurate detection of accelerations and rotations using a simple, cost-effective MEMS sensor with high detection accuracy, distinguishing between acceleration and rotation frequencies to determine the type of movement, thus simplifying production and operation.
Implementation Method 1
drive elements for driving the driving mass/es in oscillation at a driving frequency relative to the sensing mass/es in order to subject them to Coriolis forces during a rotation of the substrate about an arbitrary spatial axis
Data Source
AI summary
Micro-electro-mechanical-systems (MEMS) sensors and methods for detecting rates of rotation thereof. The MEMS sensor has at least one driving mass that oscillates along the x-axis, and at least one sensing mass coupled to the driving mass so that the sensing and driving masses move relative to each other in the x direction and are coupled for rotation together about the y and/or z axes. At least one anchor spring couples the driving or sensing mass to an anchor secured to a substrate. Rotation of the MEMS sensor is sensed by sensing relative movement between the substrate and sensing mass. During its oscillation, the driving mass generates an imbalance of the driving and sensing masses with respect to the anchor, and Coriolis forces cause the sensing and driving masses to rotate together about the y or z axis when the MEMS sensor rotates about the y or z axis.