Rotation-Rate Sensor with Orthogonal Seismic Masses
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Solution Overview
Problem
Existing rotation-rate sensors are prone to spurious signals due to interference from inertia and angular accelerations, which complicates the correlation of measured capacitances with rotation rates, especially in multi-channel designs.
Innovation Solution
A compact rotation-rate sensor design utilizing four seismic masses, where the primary and secondary pairs move orthogonally and are driven to execute drive, Coriolis, and detection motions, with rocker-type coupling elements reducing sensitivity to linear and angular accelerations, allowing for simultaneous measurement of rotation rates in multiple directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple two-mass systems are connected by springs to detect rotation rates in more than one direction, then the sensor can measure rotation rates in multiple directions, but the device complexity increases and the sensor becomes more prone to interference modes
Solution Approach 1:
The patent combines multiple seismic masses (first and second primary masses, first and second secondary masses) into a single integrated system where all masses move in parallel along the main extension plane. This merging approach enables multi-directional rotation rate detection while reducing structural complexity compared to connecting separate two-mass systems with springs.
Solution Approach 2:
Each seismic mass in the patent serves multiple functions: they participate in both drive oscillation and detection oscillation, and can detect rotation rates about different axes. The primary masses detect rotation about one axis while secondary masses detect rotation about an orthogonal axis, making each mass multi-functional rather than dedicated to a single purpose.
2Productivity
If seismic masses are configured to move in parallel along orthogonal deflection directions, then the sensor can simultaneously measure multiple rotation rates, but the design complexity increases
Solution Approach 1:
The patent utilizes parallel motion along the main extension plane to achieve what traditionally would require three-dimensional spatial separation. By configuring all seismic masses to move in parallel rather than stacking them in multiple layers or separating them in space, the patent achieves multi-axis detection capability while maintaining a compact, planar structure that reduces design complexity.
3Volume of moving object
If the sensor uses a compact design with four seismic masses moving in parallel, then the sensor size is reduced, but the sensitivity to interference from linear and angular accelerations may increase
Solution Approach 1:
The patent converts the potential harmful effect of parallel mass configuration (increased sensitivity to interference) into a benefit by using differential measurement techniques. The evaluation electronics are configured to detect differential motion between primary and secondary masses, which allows the system to reject common-mode interference from linear and angular accelerations while maintaining compact dimensions.
Solution Approach 2:
The patent introduces rocker-type coupling elements as intermediaries between the seismic masses and the fixed structure. These coupling elements provide mechanical filtering that reduces the transmission of interference forces from linear and angular accelerations to the seismic masses, thereby protecting the compact sensor design from harmful interference while maintaining its small size.
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 effectively reduces spurious signals and interference, enabling accurate measurement of rotation rates in multiple directions while maintaining a compact form, thus improving the reliability and precision of rotation-rate sensing.
Implementation Method 1
If a rotation rate is present, the Coriolis force excites an antiparallel detection oscillation which is measured capacitively and converted by an evaluation electronics into a rotation rate.
Implementation Method 2
the detection motion of the first and of the second secondary mass, viewed in a detection direction extending orthogonally to the main extension plane, takes place capacitively between both the first and the second secondary mass, on the one hand, and the substrate, on the other hand
Data Source
AI summary
A rotation-rate sensor having a substrate with main extension plane, for detecting a rotation rate, extending in a direction parallel/orthogonal to the main plane; the sensor including a primary/secondary pair of seismic masses; the primary pair having first/second primary masses; the secondary pair having first/second secondary masses; the first/second primary masses being movable relative to the substrate along a primary deflection direction extending parallel to the main plane; the first/second secondary masses being movable relative to the substrate along a secondary deflection direction extending parallel to the main plane; the first/second primary masses and the first/second primary masses being movable antiparallel or parallel to one another corresponding to the deflection direction, essentially extending orthogonally to the secondary deflection direction; and the primary pair and/or secondary pair being drivable so that, based on sensor rotation, the Coriolis force leads to deflection of the first/second primary masses and/or the first/second secondary masses.