Capacitive BAW Disk Gyroscope Self-Calibration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
State-of-the-art micromachined vibrating gyros face challenges in reducing flicker noise floor and bias uncertainty without increasing mass and drive amplitude, which is difficult to achieve in low power and small size, especially in dynamic angular rate environments.
Innovation Solution
A capacitive bulk acoustic wave disk gyro operates in a closed loop mode with a self-calibration system that interchanges anti-nodal and nodal axes by swapping anti-nodal forcer electrodes with nodal pickoff electrodes and vice versa to effectively self-calibrate gyro bias, allowing for real-time bias observation and removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mass and drive amplitude are increased to reduce noise floor and improve bias stability, then noise and bias stability improve, but device size and power consumption increase
Solution Approach 1:
The patent changes the operating frequency parameter from low frequency (3-30 kHz) to high frequency (100-1000 kHz) bulk acoustic wave mode. This parameter change enables reduced mass and drive amplitude while maintaining or improving noise and bias stability, directly resolving the contradiction between reliability and mass.
Solution Approach 2:
The patent replaces the traditional mechanical vibration-based gyroscope system with a capacitive bulk acoustic wave system that operates at higher frequencies. This substitution allows for reduced mass and lower power consumption while achieving improved bias stability through the inherent properties of BAW resonators.
2Reliability
If mass and drive amplitude are increased to reduce noise floor and improve bias stability, then noise and bias stability improve, but power consumption increases
Solution Approach 1:
The patent changes the operating frequency parameter to high frequency BAW mode, which enables reduced drive amplitude requirements. This parameter change achieves improved bias stability with lower power consumption, resolving the contradiction between reliability and energy usage.
Solution Approach 2:
The patent utilizes bulk acoustic wave vibrations at high frequencies (100-1000 kHz) to achieve sensitive Coriolis measurement. This vibration approach at higher frequencies provides improved bias stability while requiring less drive amplitude and thus lower power consumption compared to traditional low-frequency mechanical vibrations.
3Measurement precision
If drive amplitude is increased to improve sensitivity, then sensitivity improves, but device size increases
Solution Approach 1:
The patent changes the frequency parameter to high frequency BAW mode, which enables high sensitivity with reduced drive amplitude. This parameter change achieves improved measurement precision without increasing device size, as the high-frequency resonator can achieve sufficient sensitivity at lower amplitudes.
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 improves noise and bias stability by more than an order of magnitude, enabling higher sensitivity, reduced size, and increased applications, while maintaining high Q in air and simplifying packaging.
Implementation Method 1
A specific class of gyro may be identified in which polarity of the gyro bias is reversed when the drive and sense axes are interchanged. This particular class of gyro may be identified as Class II Coriolis Vibratory Gyro (CVG)
Implementation Method 2
capacitive bulk acoustic wave disk gyro operated in a closed loop mode
Implementation Method 3
capacitive bulk acoustic wave disk gyro additionally comprises a plurality of electrodes having pickoff electrodes and forcing electrodes
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The apparatus in one embodiment may have capacitive bulk acoustic wave disk gyro operated in a closed loop mode. A self-calibration system may be operatively coupled to the capacitive bulk acoustic wave disk gyroscope. Self-calibration of gyro bias of the gyro may be implemented by interchanging an anti-nodal axis with a nodal axis of the gyro.