Decoupled Drive MEMS Gyroscope Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing angular velocity sensors using vibratory rate gyroscopes face challenges in accurately measuring angular velocity due to non-idealities in electrostatic actuators, which can introduce errors in the measurement of angular velocity.
Innovation Solution
The proposed angular rate sensor incorporates a decoupled drive system where the drive mass is separated from the rotating proof mass, with electrostatic actuators attached to the drive mass. This configuration minimizes the effect of non-ideal electrostatic actuator forces on the rotating proof mass, enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If electrostatic actuators are directly attached to the rotating proof mass, then the device complexity is reduced, but measurement precision deteriorates due to non-ideal actuator forces
Solution Approach 1:
The system is divided into two separate mass systems: a drive mass for actuation and a rotating proof mass for sensing. The electrostatic actuators are attached only to the drive mass, which is mechanically coupled to the rotating proof mass through flexible elements. This segmentation isolates the non-ideal actuator forces from the proof mass, preventing measurement errors while maintaining structural feasibility.
Solution Approach 2:
The disturbing element (electrostatic actuator) is extracted from direct contact with the rotating proof mass. By placing the actuators on a separate drive mass and coupling the two masses through flexible elements, the harmful non-ideal forces are taken out of the sensing path, allowing accurate angular velocity measurement.
2Measurement precision
If a decoupled drive system with separate drive mass and proof mass is used, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The drive mass and rotating proof mass are merged into a single integrated structure that moves together as a coupled system. The flexible elements provide the necessary mechanical coupling while allowing differential motion. This merging reduces the number of separate components and simplifies the overall device architecture while maintaining the decoupled actuation-sensing functionality.
Solution Approach 2:
The drive mass serves multiple functions: it acts as both the actuation platform for electrostatic forces and as a mechanical coupling element to transfer motion to the rotating proof mass. The flexible elements serve dual purposes of mechanical support and motion transmission. This multi-functionality reduces component count and simplifies the device structure.
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 decoupled drive system effectively reduces measurement errors caused by non-ideal electrostatic actuator forces, leading to improved sensitivity and accuracy in measuring angular velocity.
Implementation Method 1
an actuator for driving the drive mass into oscillation along a first axis in plane to the substrate
Implementation Method 2
a first transducer to sense the motion of the rotating structure in response to a Coriolis force in a sense mode
Data Source
Figure 1a
Figure 1b
Figure 1c
AI summary
In a first aspect, the angular rate sensor comprises a substrate and a rotating structure anchored to the substrate. The angular rate sensor also includes a drive mass anchored to the substrate and an element coupling the drive mass and the rotating structure. The angular rate sensor further includes an actuator for driving the drive mass into oscillation along a first axis in plane to the substrate and for driving the rotating structure into rotational oscillation around a second axis normal to the substrate; a first transducer to sense the motion of the rotating structure in response to a Coriolis force in a sense mode; and a second transducer to sense the motion of the sensor during a drive mode. In a second aspect the angular rate sensor comprises a substrate and two shear masses which are parallel to the substrate and anchored to the substrate via flexible elements.