MEMS Gyroscope Quadrature Compensation via Drive Frame Torque
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Solution Overview
Problem
MEMS-based gyroscope sensors face challenges in achieving reliable manufacturing methods for well-balanced devices due to manufacturing defects that introduce asymmetry, leading to coupling between excitation and detection modes, resulting in high errors in output signals.
Innovation Solution
A gyroscope sensor design with inertial masses excited by a drive structure that includes static and displaceable parts, where the drive frame participates in both the sense and drive mode, allowing for quadrature compensation by generating torque to correct unwanted deflections and reduce electrostatic softening effects, using capacitance changes between inertial masses and electrodes to apply corrective voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If manufacturing methods are simplified for mass production, then productivity increases, but manufacturing precision deteriorates leading to asymmetry and quadrature errors
Solution Approach 1:
The patent applies preliminary action by introducing quadrature compensation electrodes and correction members during the manufacturing process. These components are pre-configured to counteract the asymmetry and quadrature errors that will arise from simplified mass production manufacturing, allowing standard fabrication processes to be used while still achieving high precision through pre-built correction mechanisms.
Solution Approach 2:
The patent utilizes parameter changes by adjusting the capacitance values of the quadrature compensation electrodes and the electrostatic forces of the correction members. By varying these electrical parameters, the system can dynamically compensate for manufacturing asymmetries without requiring tighter mechanical tolerances, thus maintaining productivity while improving precision.
2Measurement precision
If quadrature compensation is added to correct manufacturing defects, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies universality by designing the quadrature compensation electrodes to serve multiple functions: they act as both drive electrodes for exciting the inertial mass and as compensation electrodes for correcting quadrature errors. The correction members similarly participate in both the sense mode and drive mode, reducing the need for separate dedicated components and thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the quadrature compensation function with the existing drive structure by integrating correction members into the drive frame. This combination allows the same structural elements to perform both compensation and driving functions, avoiding the need for entirely separate compensation mechanisms and thus limiting complexity growth.
3Measurement precision
If electrostatic forces are increased for quadrature compensation, then measurement precision improves, but harmful factors increase due to electrostatic softening effects
Solution Approach 1:
The patent applies local quality by positioning the quadrature compensation electrodes and correction members at specific locations where they can generate targeted electrostatic forces. By concentrating the compensation action in localized regions rather than applying uniform electrostatic fields across the entire device, the system achieves effective quadrature correction while minimizing the overall electrostatic softening effects on the inertial mass.
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 effectively minimizes quadrature errors by optimizing the overlap and electrostatic forces between correction members and electrodes, improving the gyroscope's sensitivity axis detection and reducing the impact of manufacturing defects on output signal accuracy.
Implementation Method 1
applying a voltage across the first and second correction electrode, thereby subjecting the first elongated correction member to an electrostatic force
Implementation Method 2
The drive structure comprises static parts and a displaceable part... when a voltage is applied to the further electrode set the drive frame is set in motion
Implementation Method 3
a rotation of the respective inertial mass about the detection axis results in a capacitance change of a first sign between one of the first electrode or the second electrode, and the first inertial mass
Implementation Method 4
When the inertial mass is subjected to a rotation away from a horizontal orientation about the sensitivity axis which is perpendicular to the excitation axis, the inertial mass rotates about a detection axis due to the coriolis force
Data Source
Figure 1a~1b
Figure 2~3
Figure 4a
AI summary
The present invention relates to a gyroscope sensor (102) for detecting a rotational motion about a sensitivity axis (104) and comprising means for quadrature compensation. The gyroscope sensor comprises a total inertial mass (105) comprising a first inertial mass (106) and a second inertial mass (108) physically attached to each other and arranged such that a rotation of the first inertial mass about a detection axis caused by the coriolis force when the gyroscope sensor is subjected to a rotation about a sensitivity axis. The gyroscope further comprises a first drive structure having a displaceable drive frame which may cause a respective of the first or second inertial mass to rotate about the detection axis in order to compensate for quadrature errors originating from faulty coupling between a drive mode and a sense mode of the gyroscope sensor.