Two-Wire Reference Accelerometer Self-Calibration
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Solution Overview
Problem
Existing line drive accelerometers require frequent calibration by certified stations, reducing the convenience of back-to-back calibration techniques due to the need for a reference accelerometer with known sensitivity.
Innovation Solution
A two-wire reference accelerometer with integrated mechanical transducing and self-calibration capability based on gravity, allowing for self-calibration using direct and reverse bias measurements without modifying components or circuit functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the reference accelerometer is regularly calibrated by a NIST-certified calibration station or at a certified calibration laboratory, then the calibration accuracy is ensured, but the convenience and frequency of back-to-back calibration operations are reduced
Solution Approach 1:
The reference accelerometer is equipped with self-calibration capability that allows it to maintain its own calibration status without requiring external calibration stations. The device uses its integrated transducer and electronic components to perform direct and reverse bias measurements, enabling it to self-verify and self-adjust its sensitivity parameters.
Solution Approach 2:
The self-calibration process utilizes changes in the accelerometer's output signal in response to gravity-induced acceleration. By measuring the output at different orientations (direct and reverse bias), the system changes the acceleration parameter to calibrate the sensitivity without external equipment.
2Reliability
If the reference accelerometer uses a three-wire interface (power, signal and common), then the signal transmission is reliable, but the device complexity and cable requirements increase
Solution Approach 1:
The patent combines the power and signal transmission functions into a single two-wire interface. The same wire that carries the power supply signal also carries the accelerometer output signal, eliminating the need for separate power and signal cables while maintaining signal transmission reliability.
Solution Approach 2:
The two-wire interface is designed to serve multiple functions simultaneously: it provides both power supply to the accelerometer and carries the output signal to the measurement system. This multi-functional interface reduces the overall system complexity while maintaining all necessary functions.
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
Enables convenient self-calibration of the reference accelerometer, eliminating the need for external calibration resources and ensuring accurate sensitivity parameters over time.
Implementation Method 1
line drive accelerometers have been developed that combine a piezoelectric or other AC response transducer
Implementation Method 2
self-calibration capability based on gravity only
Data Source
AI summary
A two-wire reference accelerometer includes integrated mechanical transducing and self-calibration capability based on gravity only. The reference accelerometer includes an external two-wire connector and an internal three-wire transducer that responds to both steady-state acceleration and time-varying accelerations by producing a modulated transducer output signal having a steady-state waveform when the transducer senses steady state acceleration and a time-varying waveform when the transducer senses time-varying accelerations. A signal conditioning circuit conditions the transducer output signal and applies it to the two-wire electrical connector as a modulated reference accelerometer output signal. The transducer and the signal conditioning circuit can operate without modification in either a DUT calibration mode or a self-calibration mode. The self-calibration mode determines the 1 g output sensitivity of the reference accelerometer from first and second readings of the reference accelerometer output signal taken while the reference accelerometer rests on a non-accelerating surface in respective non-inverted and inverted orientations.