Micromechanical Yaw Rate Sensor Spring Segmentation
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Solution Overview
Problem
Existing yaw rate sensors suffer from unwanted crosstalk and interference due to manufacturing inaccuracies, leading to parasitic modes and interference deflections, which affect the accuracy of yaw-rate measurements in safety-critical applications like vehicle dynamics control systems.
Innovation Solution
A micromechanical yaw rate sensor design featuring a suspension spring element with two bar sections aligned essentially parallel to each other and connected by a coupling section, allowing for adjustable linear deflection behavior, which suppresses quadrature signals and reduces interference by preventing rectified deflections and associated signal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional suspension springs are used in yaw rate sensors, then the seismic masses can be suspended with simple structure, but manufacturing inaccuracies cause unwanted flank angles that generate quadrature signals and interference
Solution Approach 1:
The suspension spring is divided into multiple beam sections (first beam section, second beam section, third beam section) connected by connecting sections. This segmentation allows each section to be optimized independently, with the first and second beam sections being substantially parallel to suppress quadrature signals while the third beam section provides the necessary flank angle for seismic mass suspension.
Solution Approach 2:
Different sections of the spring have different geometric properties tailored to specific functions: the first and second beam sections are substantially parallel to minimize interference, while the third beam section has a specific flank angle to enable proper seismic mass suspension. This local optimization resolves the contradiction between simple structure and manufacturing precision.
2Device complexity
If seismic masses are suspended directly on the substrate, then the suspension structure is simple, but deflection in drive and readout modes causes crosstalk between vibration modes
Solution Approach 1:
The suspension system is segmented into multiple functional components: the multi-section spring for seismic mass suspension, the coupling beam for coupling seismic masses, and the torsion spring for rotational suspension. This segmentation allows each component to be optimized for its specific function, reducing crosstalk while maintaining structural simplicity.
3Measurement precision
If coupling units are used to couple seismic masses, then crosstalk between vibration modes is reduced, but the coupling becomes sensitive to rectified disturbance excitations like impacts
Solution Approach 1:
The coupling beam merges the functions of seismic mass coupling and disturbance filtering. By suspending the coupling beam from a torsion spring and connecting it to both seismic masses, the system achieves mode separation while the torsion spring's rotational compliance filters out rectified disturbance excitations, resolving the contradiction between precision and robustness.
4Measurement precision
If springs with small flank angles are used to reduce quadrature signals, then manufacturing accuracy requirements increase, but larger flank angles cause more interference signals
Solution Approach 1:
The spring is segmented into multiple beam sections where the first and second beam sections are substantially parallel (suppressing quadrature) while the third beam section provides the necessary flank angle. This segmentation allows the system to achieve both quadrature suppression and adequate flank angle without excessive manufacturing precision requirements.
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 design significantly reduces interference and manufacturing inaccuracies, enhancing the precision and reliability of yaw-rate measurements by maintaining a linear deflection behavior over a large deflection interval with smaller dimensions and lower interference, thus improving the accuracy of yaw-rate sensors in automotive applications.
Implementation Method 1
a suspension spring element (10) with two bar sections (11), which in the undeflected state are aligned essentially parallel to one another... the bar sections (11) are displaceable relative to one another with respect to their longitudinal direction
Implementation Method 2
The coupling beam is suspended from a torsion spring on the substrate
Implementation Method 3
Yaw rate sensors are commonly used to detect the angular velocity of a system about at least one defined axis
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
Micromechanical rate-of-rotation sensor comprising at least one substrate (30), wherein the base area of the substrate is oriented parallel to the x-y plane of a system of Cartesian coordinates, at least two seismic masses (1, 1a, 1b) and at least one respective suspension spring element (10, 11) for suspension of the seismic mass (1, 1a, 1b) on the substrate (30), wherein the at least two seismic masses (1, 1a, 1b) are coupled to one another by at least one coupling beam (2, 2a, 2b) and at least one of the suspension spring elements (10) comprises at least two beam sections (11) which, in the undeflected state, are oriented substantially parallel to one another or have an angular width of less than 45° with respect to one another, and one or a plurality of connecting sections (12) which connect the beam sections (11) to one another, wherein the beam sections can be displaced relative to one another with regard to their longitudinal direction.