MEMS Gyroscope Quadrature Compensation via Inverted Electrostatic Actuation
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Solution Overview
Problem
Gyroscopes with out-of-plane primary motion face challenges in quadrature error compensation due to the complexity of fabricating and maintaining temperature robustness in existing electrostatic quadrature suppression configurations, which are not applicable for such motion directions.
Innovation Solution
A microelectromechanical gyroscope structure with a seismic mass suspended by a spring structure, featuring conductors that create a modulated electrostatic force orthogonal to the primary oscillation, allowing for efficient quadrature compensation by adjusting the overlap area between surfaces, thereby aligning the oscillation accurately with out-of-plane motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrostatic quadrature suppression configuration is used for out-of-plane primary motion, then quadrature compensation is achieved, but manufacturing complexity and temperature robustness deteriorate
Solution Approach 1:
Instead of applying electrostatic force from stationary electrodes surrounding the seismic mass (prior art approach), the patent inverts the configuration by having the seismic mass itself move with the oscillation and carry conductors that interact with stationary electrodes. This inversion simplifies the structure for out-of-plane motion while maintaining quadrature compensation effectiveness.
Solution Approach 2:
The patent transitions from in-plane electrostatic compensation configurations to out-of-plane motion compensation by orienting the conductor interaction in a different spatial dimension. The first conductor on the seismic mass and second conductor on the body element are arranged to create electrostatic force in the direction orthogonal to primary oscillation, enabling quadrature compensation for out-of-plane motion.
2Measurement precision
If electrostatic quadrature suppression configuration is used for out-of-plane primary motion, then quadrature compensation is achieved, but temperature robustness deteriorates
Solution Approach 1:
The inverted configuration where the seismic mass carries the moving conductor reduces sensitivity to temperature variations by eliminating the need for complex stationary electrode arrangements that are difficult to fabricate with temperature compensation. The simplified structure inherently provides better temperature robustness.
3Measurement precision
If prior art surrounding stationary electrode configuration is used, then quadrature error suppression is achieved, but ease of manufacture deteriorates
Solution Approach 1:
The patent inverts the prior art configuration by placing the moving conductor on the seismic mass rather than using stationary surrounding electrodes. This inversion dramatically simplifies fabrication since the seismic mass and its conductors can be formed in standard MEMS processes without requiring complex surrounding electrode structures.
Solution Approach 2:
The patent divides the electrostatic compensation function into separate components: the seismic mass carries the first conductor, and the body element carries the second conductor. This segmentation allows each component to be fabricated independently using standard processes, improving ease of manufacture while maintaining quadrature suppression functionality.
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 configuration effectively reduces unwanted in-plane movement, enhances manufacturing simplicity, and improves temperature robustness, achieving accurate quadrature compensation in gyroscope structures with out-of-plane primary motion.
Implementation Method 1
A voltage element is arranged to create between the first surface and the second surface a potential difference and thereby induce an electrostatic force that is in the second direction and is modulated by the primary oscillation of the seismic mass
Data Source
Figure 1~2B
Figure 3A~4
Figure 5A~5B
AI summary
A microelectromechanical gyroscope structure that comprises a seismic mass, a body element, and a spring structure suspending the seismic mass to the body element. In primary oscillation at least part of the seismic mass oscillates in out-of-plane direction. A first conductor is arranged to move with the seismic mass, and a second conductor is attached to the body element. The conductors include adjacent surfaces that extend in the first direction and the third direction. A voltage element is arranged to create between the first surface and the second surface a potential difference and thereby induce an electrostatic force in the second direction and modulated by the primary oscillation of the seismic mass.