MEMS Gyroscope Accelerometer Integration via Anti-Phase Oscillation
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Solution Overview
Problem
Current microelectromechanical devices integrating gyroscopes and accelerometers face limitations in terms of size and power consumption, necessitating the development of a compact and versatile solution that can simultaneously measure acceleration and angular velocity effectively.
Innovation Solution
A microelectromechanical device with a supporting structure, two sensing masses, and a driving device that maintains these masses in oscillation in phase opposition, allowing for differential capacitive coupling to sense displacements along multiple axes, enabling the device to function as both an accelerometer and a gyroscope through distinct processing modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If distinct accelerometer and gyroscope devices are provided, then measurement capability is improved, but device dimensions and power consumption increase
Solution Approach 1:
The patent combines accelerometer and gyroscope functions into a single integrated device with shared mechanical structures (masses, springs, electrodes) and common support, eliminating the need for separate devices while maintaining full measurement capabilities for both linear acceleration and angular velocity
Solution Approach 2:
The sensing masses are designed to perform multiple functions: they serve as both accelerometric sensors (sensing linear acceleration through displacement along the oscillation axis) and gyrometric sensors (sensing angular velocity through Coriolis force-induced displacement perpendicular to the oscillation axis), allowing one device to replace two specialized sensors
2Measurement precision
If distinct accelerometer and gyroscope devices are provided, then measurement capability is improved, but power consumption increases
Solution Approach 1:
The patent combines accelerometer and gyroscope functions into a single integrated device with shared mechanical structures (masses, springs, electrodes) and common support, eliminating the need for separate devices while maintaining full measurement capabilities for both linear acceleration and angular velocity
Solution Approach 2:
The sensing masses are designed to perform multiple functions: they serve as both accelerometric sensors (sensing linear acceleration through displacement along the oscillation axis) and gyrometric sensors (sensing angular velocity through Coriolis force-induced displacement perpendicular to the oscillation axis), allowing one device to replace two specialized sensors
3Measurement precision
If two sensing masses oscillate in phase opposition, then signal-to-noise ratio is improved, but device complexity increases
Solution Approach 1:
The patent introduces asymmetric drive signals with opposite phases applied to the two sensing masses, creating anti-phase oscillation that generates differential signals. This asymmetry in drive timing compensates for the symmetric mechanical structure, enabling noise cancellation through differential measurement while maintaining structural simplicity
Solution Approach 2:
The system uses feedback control to maintain the sensing masses in anti-phase oscillation, with the control system adjusting drive signals based on detected displacement signals from capacitive sensors. This feedback mechanism ensures stable differential operation and optimal signal-to-noise ratio while automating the complexity of phase synchronization
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 allows for efficient amplification of relevant signals while attenuating noise, resulting in a compact, high-performance sensor that saves space and power, suitable for a wide range of applications including portable devices.
Implementation Method 1
The movable mass and the stator are capacitively coupled through a plurality of respective comb-fingered and mutually facing electrodes, so as to form capacitors. The movement of the movable mass with respect to the stator modifies the capacitance of the capacitors
Implementation Method 2
by supplying appropriate biasing voltages, it is possible to apply an electrostatic force to the movable mass to set it in motion
Implementation Method 3
The other mass is driven in oscillatory (translational or rotational) motion and, in the case of rotation of the microstructure with respect to a pre-set gyroscopic axis at an angular velocity, is subject to a Coriolis force proportional to the angular velocity itself
Implementation Method 4
These displacements are countered by the elastic action of the springs
Data Source
AI summary
A microelectromechanical device includes: a supporting structure; two sensing masses, movable with respect to the supporting structure according to a first axis and a respective second axis; a driving device for maintaining the sensing masses in oscillation along the first axis in phase opposition; sensing units for supplying sensing signals indicative of displacements respectively of the sensing masses according to the respective second axis; processing components for combining the sensing signals so as to: in a first sensing mode, amplify effects on the sensing signals of concordant displacements and attenuate effects of discordant displacements of the sensing masses; and in a second sensing mode, amplify effects on the sensing signals of discordant displacements and attenuate effects of concordant displacements of the sensing masses.