Two-DOF Dithering Platform for MEMS Sensor Calibration
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Solution Overview
Problem
MEMS inertial sensors experience performance drift over time due to the interplay between electronic and mechanical components, leading to bias and scale factor changes that existing technologies struggle to effectively correct.
Innovation Solution
A two-degree of freedom dithering platform is introduced, which includes an in-plane rotator to correct bias drift by oscillating the MEMS sensor in its plane and an out-of-plane rotator to correct scale factor drift by oscillating the sensor out of its plane, using rotor layers and capacitive pickoff plates to sense and control these movements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single-degree-of-freedom dithering mechanism is used, then the device complexity is reduced, but it cannot simultaneously correct both bias drift and scale factor drift
Solution Approach 1:
The dithering platform is segmented into two independent rotational degrees of freedom: in-plane rotation (correcting bias drift) and out-of-plane rotation (correcting scale factor drift). This segmentation allows each degree of freedom to address a specific drift type independently, achieving comprehensive drift correction without requiring a single complex mechanism.
Solution Approach 2:
The patent transitions from a single-degree-of-freedom dithering approach to a two-degree-of-freedom system by adding the out-of-plane rotational dimension. This dimensional expansion enables the system to correct both bias and scale factor drift simultaneously, resolving the limitation of single-axis dithering mechanisms.
2Adaptability or versatility
If the rotor layers are fully separated from the MEMS sensor layer, then the dithering motion freedom is improved, but the structural stability deteriorates
Solution Approach 1:
The rotor layers are designed with dynamic connectivity: they are separated from the MEMS sensor layer to enable free dithering motion, but remain connected through flexible suspension structures that provide structural stability. This dynamic design allows the system to achieve both motion freedom and structural integrity simultaneously.
Solution Approach 2:
The patent uses flexible suspension films and thin membrane structures to connect the rotor layers to the substrate. These flexible elements allow the rotor layers to rotate freely in both in-plane and out-of-plane directions while maintaining structural stability and preventing complete separation.
3Measurement precision
If complex calibration procedures are used, then the measurement precision is improved, but the calibration time increases
Solution Approach 1:
The dual-degree-of-freedom dithering platform enables self-calibration by automatically modulating the sensor input through controlled in-plane and out-of-plane rotations. This self-service mechanism eliminates the need for complex external calibration procedures, achieving high measurement precision while reducing calibration time.
Solution Approach 2:
The calibration process uses periodic dithering motions at specific frequencies to modulate the sensor input. By applying periodic in-plane and out-of-plane rotations, the system can extract calibration parameters efficiently through frequency-domain analysis, reducing calibration time while maintaining precision.
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 dithering platform effectively eliminates bias and scale factor drift by modulating the sensor input, allowing for precise calibration and maintaining accurate measurements over time.
Implementation Method 1
an in-plane rotator to rotate the MEMS sensor in the plane of the MEMS sensor layer
Implementation Method 2
an out-of-plane rotator to rotate the MEMS sensor out of the plane
Implementation Method 3
using rotor layers and capacitive pickoff plates to sense and control these movements
Data Source
AI summary
Systems and methods for two degree of freedom dithering for micro-electromechanical system (MEMS) sensor calibration are provided. In one embodiment, a method for a device comprises forming a MEMS sensor layer, the MEMS sensor layer comprising a MEMS sensor and an in-plane rotator to rotate the MEMS sensor in the plane of the MEMS sensor layer. Further, the method comprises forming a first and second rotor layer and bonding the first rotor layer to a top surface and the second rotor layer to the bottom surface of the MEMS sensor layer, such that a first and second rotor portion of the first and second rotor layers connect to the MEMS sensor. Also, the method comprises separating the first and second rotor portions from the first and second rotor layers, wherein the first and second rotor portions and the MEMS sensor rotate about an in-plane axis of the MEMS sensor layer.