Yaw Rate Sensor Segmented Coriolis Masses
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Solution Overview
Problem
Conventional yaw rate sensors are sensitive to linear and rotational accelerations, which can result in false signals, especially when rotational oscillations occur at frequencies matching the sensor's drive frequency and in phase with the Coriolis force.
Innovation Solution
A yaw rate sensor design featuring two Coriolis masses with specific partial areas and electrodes, where the attachment and configuration of these masses and electrodes on a substrate or drive device allow changes caused by deflections to compensate for each other, reducing the influence of rotational accelerations on the measuring signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional yaw rate sensors use planar oscillating masses or rotating masses in the plane, then the sensor can detect yaw rates around a direction parallel to the substrate plane, but the sensor becomes sensitive to linear accelerations and rotational accelerations that induce false signals
Solution Approach 1:
The Coriolis mass is divided into four partial areas (first, second, third, and fourth partial areas) with different distances from the axis of symmetry. This segmentation allows different capacitance changes to occur in each partial area during rotational acceleration, enabling compensation through differential measurement and reducing false signals from interfering accelerations.
Solution Approach 2:
Different partial areas of the Coriolis mass are positioned at different distances from the axis of symmetry, creating local variations in mass distribution and capacitance characteristics. The first and third partial areas are farther from the axis while the second and fourth are closer, allowing each region to respond differently to rotational acceleration and enabling selective compensation.
2Measurement precision
If the sensor uses two oscillating masses driven in anti-parallel mode, then the Coriolis force can be detected via capacitance change, but rotational oscillations at the drive frequency in phase with the Coriolis force produce particularly large interference signals
Solution Approach 1:
The Coriolis mass is designed with asymmetric partial areas at different distances from the axis of symmetry, creating an asymmetric capacitance distribution. This asymmetry allows the sensor to differentiate between Coriolis force effects and rotational acceleration effects, as they produce different patterns of capacitance change across the partial areas, enabling rejection of interference signals.
Solution Approach 2:
The sensor uses capacitance detection to measure the position and movement of the Coriolis mass partial areas. By monitoring capacitance changes in real-time and using analysis electronics to process these signals, the system can distinguish between genuine yaw rate signals and interference from rotational oscillations, effectively filtering out false signals through feedback-based signal processing.
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 less sensitive to interfering accelerations, effectively differentiating between actual yaw rate and rotational acceleration effects, thereby minimizing interference in the measuring signal.
Implementation Method 1
the first Coriolis mass and the second Coriolis mass, for a yaw rate around the first direction, experiencing a Coriolis acceleration in parallel to a detection direction, which is both perpendicular to the drive direction and perpendicular to the first direction
Implementation Method 2
a first electrode, which forms a first capacitance with the first partial area, being situated opposite to the first partial area, a second electrode, which forms a second capacitance with the second partial area, being situated opposite to the second partial area
Data Source
AI summary
A yaw rate sensor, including a substrate and a main extension plane, for detecting a yaw rate around a first direction in parallel to the main extension plane, a first Coriolis mass, and a second Coriolis mass, and a drive device configured to drive the first and second Coriolis masses in parallel to a drive direction perpendicular to the first direction, the first and second Coriolis masses, for a yaw rate around the first direction, experiencing a Coriolis acceleration in parallel to a detection direction, which is perpendicular to the drive and first directions, the first and second Coriolis masses having first/second partial areas and third/fourth partial areas, respectively. The first and third partial areas are farther from the axis of symmetry in parallel to the first direction, and the second and fourth partial areas are closer to the axis of symmetry in parallel to the first direction.