Double-Rotor Yaw Rate Sensor With Thick Spring Coupling
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Solution Overview
Problem
Modern micromechanical yaw rate sensors are susceptible to rotational accelerations about all three spatial axes and have spring structures that are thin and prone to failure.
Innovation Solution
A three-axis yaw rate sensor with a double rotor and spring structures made of polycrystalline silicon, arranged to avoid crossings and obscuration, with mechanical couplings that allow robust detection modes for all axes, using U-shaped and S-shaped springs for anti-parallel movements and torsional oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If thin spring structures are used for mechanical coupling, then the device complexity is reduced, but the reliability deteriorates due to higher failure rates
Solution Approach 1:
The spring structures are designed with increased thickness as a parameter change to improve reliability. The patent specifies that the spring structures have a thickness of 10-100 μm, which is significantly thicker than conventional spring structures, making them more resistant to rotational accelerations and less prone to failure while maintaining the required mechanical coupling function.
Solution Approach 2:
The spring structures are made from polycrystalline silicon, which provides superior mechanical properties compared to conventional materials. This material choice enhances the reliability and resistance of the spring structures to rotational accelerations about all three spatial axes while maintaining the desired structural characteristics.
2Measurement precision
If the sensor is made insensitive to rotational accelerations about all three spatial axes, then the measurement precision improves, but the device complexity increases due to additional spring structures
Solution Approach 1:
The mechanical coupling is segmented into two independent spring structures: a first spring structure for coupling the drive mode with the X-detection mode, and a second spring structure for coupling the drive mode with the Y-detection mode. This segmentation allows each spring structure to be optimized for its specific function, achieving insensitivity to rotational accelerations about all three axes while maintaining manageable complexity through functional separation.
Solution Approach 2:
The spring structures are arranged in different spatial dimensions and orientations to achieve the desired measurement precision. The first spring structure extends in one direction while the second spring structure extends in another direction, creating a three-dimensional arrangement that provides insensitivity to rotational accelerations about all three spatial axes without excessive complexity.
3Measurement precision
If substrate connections are arranged in the sensor center, then the measurement precision improves due to smaller differential length changes, but the ease of operation decreases due to constrained design flexibility
Solution Approach 1:
The substrate connections are specifically positioned in the sensor center, creating a local optimization for measurement precision. This central arrangement minimizes differential length changes upon deformation or expansion of the underlying sensor substrate, resulting in smaller changes in sensitivity and offset upon change in external environmental conditions. The design accepts reduced overall flexibility in exchange for localized precision improvement at the critical substrate connection points.
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
The sensor is resistant to rotational accelerations, has lower failure rates, and provides accurate measurements across three axes with thicker, more resilient spring structures.
Implementation Method 1
a first spring structure and/or a second spring structure which is made of and/or arranged in a polycrystalline silicon layer produced by epitaxial growth
Implementation Method 2
a first spring structure and a second spring structure... mechanical coupling of the Z-detection mode... U-shaped spring elements... S-shaped spring
Data Source
AI summary
A three-axis yaw rate sensor. The sensor includes a sensor substrate, a double rotor, and a first and a second spring structure, the substrate having a main extension plane, the main extension plane being spanned by an X-axis and a Y-axis oriented perpendicularly to the X-axis, a Z-axis being oriented perpendicularly to the main extension plane, the double rotor having a first and a second rotor, the first rotor having a first and a second seismic mass, the second rotor having a third and fourth seismic mass, the first rotor being connected to the sensor substrate via a first substrate connection, the second rotor being connected to the sensor substrate via a second substrate connection, the first rotor being connected to the second rotor via the first spring structure in such a way that a first mechanical coupling is present between the first and the second rotor.