Two-axis Rotation Rate Sensor with Counter-phase Mass Oscillators
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rotation rate sensors in automotive engineering require multiple sensors to measure rotation rates around multiple axes, leading to increased complexity, sensitivity to external vibrations, and interference modes, which can result in false signals.
Innovation Solution
A single sensor element measures rotation rates around two orthogonal axes using two seismic masses in counter-phase oscillation, ensuring symmetry conditions to isolate Coriolis forces from other accelerations, reducing interference modes and sensitivity to external vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple individual one-axis sensors are used to measure rotation rates around multiple axes, then the measurement capability is improved, but the device complexity and sensitivity to external vibrations increase
Solution Approach 1:
The patent combines multiple one-axis sensor elements into a single multiaxis sensor element that can measure rotation rates around multiple orthogonal axes simultaneously. This merging approach reduces the total number of sensors needed, simplifies the overall device structure, and eliminates the need for multiple separate drive circuits while maintaining full measurement capability across all axes.
Solution Approach 2:
The sensor element is designed to perform multiple measurement functions by detecting rotation rates around different axes using the same seismic mass and drive circuitry. The single sensor element universally measures rotation rates around at least two orthogonal axes, replacing the need for multiple specialized one-axis sensors and reducing overall system complexity.
2Adaptability or versatility
If multiple individual one-axis sensors are used to measure rotation rates around multiple axes, then the measurement capability is improved, but the sensitivity to external vibrations increases
Solution Approach 1:
By merging multiple measurement functions into a single sensor element with shared seismic masses and drive circuits, the patent reduces the overall sensitivity to external vibrations. The combined structure minimizes the number of independent vibration-sensitive components, and the differential measurement approach using counter-phase oscillating masses helps cancel out common-mode vibration interference.
3Adaptability or versatility
If multiple individual one-axis sensors are used, then the measurement capability is improved, but interference modes and false signals increase
Solution Approach 1:
The patent merges multiple measurement functions into a single sensor element, which reduces the total number of interference modes present in the system. Since interference modes are frequency-specific and arise from the mechanical and electrical structure, having a single unified sensor element rather than multiple separate sensors reduces the cumulative interference across the frequency spectrum.
Solution Approach 2:
The patent employs counter-phase oscillation of seismic masses, creating an asymmetric drive pattern where masses oscillate in opposite directions. This asymmetric approach generates Coriolis forces that are differential in nature, allowing the measurement system to distinguish true rotation signals from symmetric interference modes and false signals.
4Device complexity
If a single sensor element with two seismic masses is used, then the device complexity is reduced, but the measurement of multiple axes may be compromised
Solution Approach 1:
The single sensor element is designed with universal measurement capability by incorporating at least two seismic masses that can independently oscillate in counter-phase. The sensor element can measure rotation rates around multiple orthogonal axes simultaneously, making it a multi-functional device that replaces multiple specialized sensors while maintaining full measurement adaptability.
Solution Approach 2:
The patent employs dynamic counter-phase oscillation of the seismic masses, where the masses are driven to oscillate in opposite directions at controlled frequencies. This dynamic approach enables the single sensor element to detect Coriolis forces induced by rotation around multiple axes, providing versatile measurement capability through time-varying mechanical behavior rather than static structural arrangements.
5Device complexity
If a single drive circuit is used for the sensor, then the device complexity is reduced, but the drive capability for multiple axes may be compromised
Solution Approach 1:
The single drive circuit employs dynamic control to oscillate multiple seismic masses in counter-phase by modulating the drive signals in time. The circuit can selectively excite different mass pairs at different frequencies to measure rotation around different axes, providing full drive capability through time-multiplexed dynamic operation rather than requiring separate static drive circuits for each axis.
Solution Approach 2:
The drive circuit uses periodic oscillation signals to drive the seismic masses in counter-phase, with the ability to switch between different oscillation frequencies and patterns. By applying periodic drive forces at specific frequencies, the single circuit can sequentially or simultaneously excite different mass combinations to enable measurement around multiple axes, maintaining full drive capability through frequency-domain multiplexing.
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 approach allows for a compact, robust, and interference-reduced sensor design that effectively measures rotation rates around two axes with reduced sensitivity to external accelerations, eliminating false signals and simplifying drive circuits and wiring.
Implementation Method 1
The rotation rate sensor provided according to the present invention is based on detecting a rotation rate of the sensor by way of the Coriolis forces acting on two mass oscillators
Implementation Method 2
The functional principle of such sensors is typically based on inertial forces acting in the sensor in the event of rotations and linear accelerations, which can be measured via the deflections of seismic masses induced thereby
Data Source
AI summary
A sensor includes a substrate having a first electrode arrangement; a first mass oscillator having (a) a first mass, (b) a first mass centroid, and (c) a second electrode arrangement including a first area centroid coinciding with the first mass centroid; and a second mass oscillator having (a) a second mass equal to the first mass, (b) a second mass centroid coinciding with the first mass centroid, and (c) a third electrode arrangement including a second area centroid coinciding with the first area centroid. Areas of the second and third electrode arrangements are equal. The sensor detects respective rotation rates around axes parallel to and perpendicular to a substrate extension. The oscillators are oscillatorily connected to each other and to the substrate, are deflectable, and experience respective forces in the directions of extension of the axes upon respective rotations around the other of the axes.