Micromechanical Rate of Rotation Sensor with Mass-Symmetrical Coriolis Elements
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Solution Overview
Problem
Micromechanical structures used in yaw rate sensors face manufacturing inaccuracies leading to trench angle scattering, resulting in wobbling movements and incorrect signals due to mechanical and temperature-induced stresses, making precise measurement challenging.
Innovation Solution
The micromechanical structure is designed with mass-symmetrical Coriolis elements that act as a rigid body, coupled via torsion springs, with a compact and symmetric arrangement of electrodes and deflection elements to minimize quadrature and interference, ensuring precise measurement of yaw rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional etching processes are used to create micromechanical structures, then manufacturing is simpler and costs are lower, but trench angle scattering causes wobbling movements and quadrature errors
Solution Approach 1:
The patent applies asymmetry by intentionally designing the micromechanical structure with compensatory asymmetrical features that counteract the asymmetrical trench angle deviations. The structure includes asymmetrical mass distribution or geometrical features that balance out the quadrature errors caused by non-vertical trench walls, allowing conventional etching processes to be used while achieving precise measurements.
2Strength
If micromechanical structures are built into housing and soldered onto PCB for protection, then mechanical damage resistance improves, but bending stresses and temperature-dependent stresses increase
Solution Approach 1:
The patent changes the physical parameters of the micromechanical structure, specifically its geometrical dimensions and material properties, to reduce sensitivity to bending stresses. This includes optimizing the aspect ratio of trenches, adjusting mass distribution, and selecting materials with matched thermal expansion coefficients to minimize stress effects during housing integration and PCB mounting.
3Measurement precision
If two masses are driven in anti-parallel movement for yaw rate sensing, then linear acceleration and rotation rate can be distinguished, but manufacturing inaccuracies cause incorrect signals
Solution Approach 1:
The patent implements feedback mechanisms where the output signals from both masses are processed together to detect and compensate for quadrature errors. By continuously monitoring the signals and applying correction algorithms, the system maintains accurate yaw rate measurements despite manufacturing variations in trench angles and mass symmetry.
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 significantly reduces quadrature errors, enhances sensitivity to rotational vibrations, and provides accurate measurement of yaw rates with reduced sensitivity to mechanical and temperature-induced stresses, while maintaining a compact installation space and low production costs.
Implementation Method 1
If a yaw rate acts on the masses perpendicularly to the direction of movement, they are deflected by the Coriolis force
Implementation Method 2
the first Coriolis element and the second Coriolis element are connected to the substrate essentially close to the first axis or via means arranged on the axis, in particular torsion springs
Data Source
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AI summary
The invention proposes a micromechanical structure, in particular a rate of rotation sensor, having a substrate which has a main plane of extent, having a first Coriolis element, having a second Coriolis element, having a drive device for deflecting the first Coriolis element and the second Coriolis element out of a rest position, and having a detection device, characterized in that the first Coriolis element is designed to be symmetrical in terms of mass in relation to the second Coriolis element with respect to a first axis running parallel to the main plane of extent, wherein the first Coriolis element and the second Coriolis element have a common main plane of extent, wherein, in the rest position, the common main plane of extent runs parallel to the main plane of extent of the substrate, wherein the first Coriolis element and the second Coriolis element are each designed so as to be symmetrical in terms of mass with respect to a second axis running perpendicular to the first axis, wherein the first Coriolis element and the second Coriolis element can be driven by the drive device so as to perform a rotational oscillation about the first axis, wherein, in the case of a rate of rotation acting parallel to the projection of the second axis onto the main plane of extent, the first Coriolis element and the second Coriolis element can be deflected to realize a force action of the Coriolis force for a rotational oscillation about a third axis extending perpendicular to the main plane of extent and running through the point of intersection of the first axis and second axis, wherein the micromechanical structure has at least one first deflection element and at least one second deflection element, wherein the first deflection element and the second deflection element are designed to be symmetrical in terms of mass with respect to the first axis and with respect to the second axis, wherein the first deflection element is coupled at least to the first Coriolis element, and the second deflection element is coupled at least to the second Coriolis element, such that the force action of the Coriolis force on the first Coriolis element and on the second Coriolis element for a rotational oscillation of the first deflection element and of the second deflection element about the third axis can be detected by the detection device.