Multi-Axis MEMS Angular Rate Sensor Design
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Solution Overview
Problem
Existing MEMS angular rate sensors face challenges in achieving multiple axis sensing capability without increasing manufacturing cost and complexity, while maintaining performance.
Innovation Solution
A microelectromechanical systems (MEMS) device with a single drive mass and multiple distributed sense masses, where the drive mass is connected to the substrate via spring anchorage structures, enabling rotation around the Z-axis under electrostatic stimulus, and the sense masses are coupled to the drive mass via spring elements and a centrally located coupler to ensure 180-degree phase difference, allowing for multiple axis sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple axis sensing capability is added to MEMS angular rate sensors, then sensing versatility is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent implements multi-functionality by enabling a single MEMS sensor device to sense angular rates around multiple axes (X, Y, and Z axes) through a unified structure. The drive mass can oscillate in multiple directions, and sense masses are positioned to detect Coriolis forces from rotations about different axes, allowing one device to perform multiple sensing functions that would traditionally require separate sensors
Solution Approach 2:
The patent combines multiple sensing functions into a single integrated structure. Multiple sense masses are coupled together and positioned within the drive mass to simultaneously detect angular rates about different axes. The spring anchorage structures and coupler elements merge the mechanical functions of multiple traditional sensors into one unified MEMS device, reducing overall system complexity
2Adaptability or versatility
If multiple axis sensing capability is added to MEMS angular rate sensors, then sensing versatility is improved, but manufacturing cost increases
Solution Approach 1:
The patent segments the sensing function into distinct sense masses that are distributed within the drive mass, with each sense mass pair responsible for detecting specific axis combinations. This segmentation allows for modular fabrication where identical structural elements (spring anchorage structures, coupler elements, sense masses) can be replicated using standard MEMS batch processing techniques, reducing per-unit manufacturing cost despite the enhanced functionality
3Adaptability or versatility
If multiple axis sensing capability is added to MEMS angular rate sensors, then sensing versatility is improved, but cross talk between axes increases
Solution Approach 1:
The patent applies local quality by positioning sense masses at specific locations within the drive mass and orienting them to be sensitive to Coriolis forces from rotations about particular axes. Each sense mass pair is strategically placed to detect angular rates about specific axes while being relatively insensitive to rotations about other axes, thereby minimizing cross-talk through geometric arrangement rather than requiring complex isolation mechanisms
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 configuration simplifies drive circuitry, reduces cross talk, enables efficient die area utilization, and supports low-cost mass production while providing multiple axis sensing capability.
Implementation Method 1
The drive mass may be connected to an underlying substrate via spring anchorage structures that enable the drive mass to rotate around the Z-axis under electrostatic stimulus
Implementation Method 2
The sense masses may be coupled to the drive mass by spring elements such that oscillatory rotary motion of the drive mass results in a linear drive motion of the sense masses
Implementation Method 3
angular rate sensor having a single drive mass and multiple distributed sense masses located within a central opening of the drive mass
Data Source
AI summary
An angular rate sensor (20) includes a single drive mass (24) and distributed sense masses (36, 38, 40, 42) located within a central opening (30) of the drive mass (24). The drive mass (24) is enabled to rotate around the Z-axis (64) under electrostatic stimulus. The sense masses (36, 38, 40, 42) are coupled to the drive mass by spring elements (44, 46, 48, 50) such that oscillatory rotary motion (90) of the drive mass imparts a linear drive motion (92, 94) on the sense masses. The distributed sense masses form two pairs of sense masses, where one pair senses X- and Z-axis angular rate and the other pair senses Y- and Z-axis angular rate. The sense masses are coupled to one another via a centrally located coupler element (34) to ensure that the sense masses of each pair are moving in anti-phase.