Capacitive Gyroscope Signal Linearization Using Higher-Order Harmonics
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Solution Overview
Problem
Capacitive gyroscopes suffer from non-linearities in pick off transducer signals, leading to errors in determining the angular rate of rotation.
Innovation Solution
A capacitive gyroscope with a structure that includes primary and secondary drive and pick off transducers, a divider, and a linearizer that uses higher order harmonics to linearize the output from the primary pick off transducer, correcting angular rate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pick off transducer detects oscillation in the primary mode of motion, then the angular rate of rotation can be determined, but non-linearities in the signal cause errors in the measurement
Solution Approach 1:
The patent introduces higher order harmonic components as intermediary elements to mediate between the non-linear pick off transducer signal and the angular rate measurement. By detecting and processing these harmonic components (particularly the third harmonic), the system creates a corrective signal that compensates for the non-linearities, thereby improving measurement accuracy without changing the fundamental operation of the pick off transducer
2Measurement precision
If higher order harmonics are used to linearize the output, then measurement accuracy improves, but device complexity increases due to additional demodulators and signal processing
Solution Approach 1:
The patent makes the existing demodulator multi-functional by configuring it to detect not only the primary oscillation signal but also higher order harmonic components. This allows the same hardware component to serve multiple purposes: maintaining the primary resonance detection function while simultaneously extracting harmonic information for linearization, thereby reducing overall device complexity
Solution Approach 2:
The patent merges the harmonic detection function with the existing demodulator and signal processing chain. Instead of adding separate dedicated hardware for harmonic detection, the system combines these functions into the existing signal processing path, integrating the linearization process with the primary measurement function to minimize additional complexity
3Adaptability or versatility
If the amplitude of primary drive signal is adjusted to maintain operation above threshold angular rate of rotation, then measurement range extends, but non-linearities may increase affecting precision
Solution Approach 1:
The patent implements a feedback mechanism where the detected higher order harmonic components are used to generate corrective signals that are fed back to compensate for non-linearities. This feedback loop continuously monitors the non-linear distortion and applies real-time corrections, allowing the system to maintain high measurement accuracy across a wide range of angular rates including those above the threshold where non-linearities would normally be problematic
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
Significantly reduces errors in angular rate determination by linearizing the output, improving accuracy and precision across a wide range of rotation rates.
Implementation Method 1
a primary drive transducer configured to oscillate the structure in a primary mode of motion
Implementation Method 2
Capacitive gyroscope
Implementation Method 3
a primary pick off transducer configured to detect oscillation of the structure in the primary mode of motion
Implementation Method 4
a secondary pick off transducer configured to detect oscillation of the structure in a secondary mode of motion
Implementation Method 5
a secondary drive transducer configured to null oscillation of the structure in the secondary mode of motion
Implementation Method 6
Capacitive gyroscope
Implementation Method 7
nulling oscillations caused by the Coriolis effect
Data Source
AI summary
A capacitive gyroscope includes a vibrating structure, a primary drive transducer configured to oscillate the structure in a primary mode of motion, a primary pick off transducer to detect oscillation of the structure in the primary mode of motion. The gyroscope may also include a secondary pick off transducer configured to detect oscillation of the structure in a secondary mode of motion, a secondary drive transducer configured to null oscillation of the structure in the secondary mode of motion, a divider configured to determine an angular rate of rotation of the capacitive gyroscope based on an output from the primary pick off transducer and an output indicative of a secondary drive signal for the secondary drive transducer. The gyroscope may also include a linearizer linearize the output from the primary pick off transducer based on at least one higher order harmonic of the output from the primary pick off transducer.