Gyroscope Sensitivity Compensation via Phase Difference Detection
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Solution Overview
Problem
Micromachined gyroscopes face challenges in maintaining sensitivity due to fluctuations caused by ambient temperature, leading to variations in rate signal output, which introduces errors in rotation rate measurement.
Innovation Solution
A method is introduced to compensate for sensitivity fluctuations by adding a test signal to the quadrature tuning voltage of the gyroscope's resonator, detecting phase differences, determining the bandwidth of the accelerometer, and adjusting the frequency of the test signal to minimize errors in the output rate signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the gyroscope operates at resonance to magnify Coriolis signals, then the signal size increases and electronics requirements are eased, but the accelerometer phase shift becomes more sensitive to small frequency perturbations
Solution Approach 1:
The patent implements a feedback mechanism where the measured bandwidth is used to adjust the rate signal output. The system continuously monitors the bandwidth (which reflects phase shift sensitivity) and applies compensatory adjustments to the output signal, thereby maintaining measurement precision despite operating at resonance.
Solution Approach 2:
The patent changes the operational parameter from fixed frequency operation to variable frequency operation based on measured bandwidth. By adjusting the test signal frequency to match the accelerometer's resonant frequency and using the phase difference measurement to determine bandwidth, the system adapts to maintain optimal performance while operating at resonance.
2Adaptability or versatility
If ambient temperature varies, then the gyroscope's sensitivity fluctuates, but this introduces errors in rotation rate measurement
Solution Approach 1:
The system uses feedback by continuously measuring the bandwidth through phase difference detection and using this information to compensate for sensitivity fluctuations. The measured bandwidth serves as a feedback parameter that indicates temperature-induced sensitivity changes, allowing the system to adjust and maintain accurate rotation rate measurements across varying temperatures.
Solution Approach 2:
The gyroscope performs self-diagnosis and self-compensation by measuring its own bandwidth characteristics through the test signal method. The system uses its internal resources (accelerometer, test signal generator, phase difference detector) to automatically detect and correct for temperature-induced sensitivity variations without requiring external calibration or intervention.
3Measurement precision
If a test signal is added to quadrature tuning voltage to measure bandwidth, then sensitivity fluctuations can be compensated, but the device complexity increases
Solution Approach 1:
The test signal serves multiple functions: it measures the accelerometer's bandwidth, determines the phase difference, and enables sensitivity compensation. By using a single test signal applied to the quadrature tuning voltage for multiple measurement purposes, the patent reduces the need for separate test circuits and minimizes overall device complexity while achieving comprehensive sensitivity compensation.
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
This approach allows for accurate assessment of rotation rate by removing sensitivity-related errors from the output signal, enhancing the gyroscope's performance by stabilizing the rate signal across varying temperatures.
Implementation Method 1
The oscillation is generated with a periodic force applied to a spring-mass-damper system at the resonant frequency. Operating at resonance allows the oscillation amplitude to be large relative to the force applied.
Implementation Method 2
When the gyroscope is rotated, Coriolis acceleration is generated on the oscillating proof mass in a direction orthogonal to both the driven oscillation and the rotation. The magnitude of Coriolis acceleration is proportional to both the velocity of the oscillating proof mass and the rotation rate.
Implementation Method 3
detecting a phase difference between the quadrature error signal and the test signal
Data Source
AI summary
A method compensates for a sensitivity of an inertial sensor having a resonator and an accelerometer. The method includes adding a test signal to a quadrature tuning voltage applied to the resonator of the inertial sensor. The method also includes receiving a quadrature error signal from the accelerometer of the inertial sensor. The method also includes detecting a phase difference between the quadrature error signal and the test signal. The method also includes determining a bandwidth of the accelerometer based on the detected phase difference, the bandwidth indicating the sensitivity of the accelerometer.