Dynamically Balanced Coriolis Gyroscope with Co-located Proof Masses
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Solution Overview
Problem
Coriolis vibratory gyroscopes face limitations in achieving high Q-factors due to anchor losses, particularly in the y-mode, as the net force along the y-axis is not balanced, leading to susceptibility to anchor losses and lower Q-factors.
Innovation Solution
A dynamically balanced Coriolis vibratory gyroscope design featuring two proof masses with co-located centers of mass, where the inner proof mass is nested within the outer proof mass, and both are vibrated in anti-phase or in-phase motion to achieve force and torque balance on both x and y axes, minimizing anchor losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single proof mass is used in a conventional Coriolis vibratory gyroscope, then the device structure is simple, but anchor losses occur due to unbalanced net force on the y-axis, resulting in low Q-factor
Solution Approach 1:
The single proof mass is segmented into two separate proof masses (first and second proof masses) with equal mass. These masses are positioned symmetrically on opposite sides of the x-axis, allowing their vibratory forces to be balanced while maintaining structural simplicity. This segmentation resolves the contradiction by enabling force balance without excessive complexity.
Solution Approach 2:
The second proof mass acts as a counterweight to the first proof mass. When both masses vibrate in anti-phase, their forces cancel each other out, creating a balanced system with zero net force on the substrate. This anti-weight principle eliminates anchor losses and achieves high Q-factor while maintaining a relatively simple structure.
2Manufacturing precision
If proof masses are positioned asymmetrically to simplify manufacturing, then manufacturing precision requirements are reduced, but the net force balance is compromised, leading to increased anchor losses
Solution Approach 1:
The design intentionally introduces asymmetry in the y-positioning of the two proof masses (equal but opposite y-coordinates) while maintaining symmetry in mass and x-positioning. This controlled asymmetry enables force balance in the y-direction while keeping manufacturing requirements practical. The symmetric placement relative to the origin simplifies manufacturing compared to asymmetric designs.
3Loss of energy
If the resonator is decoupled from the substrate using a dynamically balanced structure, then anchor losses are minimized and Q-factor is maximized, but the device complexity increases
Solution Approach 1:
The force balance and torque balance functions are merged into a single symmetric configuration of two proof masses. By positioning equal masses at opposite y-coordinates and driving them in anti-phase, both force balance (eliminating anchor losses) and torque balance (maintaining rotational symmetry) are achieved simultaneously. This merging reduces complexity compared to separate balancing 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 design achieves high Q-factors on both x and y modes by eliminating net force and torque transmitted to the substrate, resulting in improved performance and accuracy in measuring angular velocity and acceleration.
Implementation Method 1
vibrating the inner and outer proof masses in anti-phase or in-phase motion to achieve force and torque balance
Implementation Method 2
A dynamically balanced Coriolis vibratory gyroscope design featuring two proof masses with co-located centers of mass
Implementation Method 3
Coriolis vibratory gyroscopes (CVGs)
Data Source
AI summary
The improvement includes an outer proof mass having a corresponding center of mass; and an inner proof mass having a corresponding center of mass, where the corresponding centers of mass of the outer proof mass and the inner proof mass are approximately co-located. Thus, a double Foucault pendulum is essentially provided in a micromachined gyroscope.