Sensor Module Filtering for Vibration Rectification Error Cancellation
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Solution Overview
Problem
Existing sensor modules face limitations in correcting vibration rectification errors due to non-linearity in low-pass filters, particularly in adjusting the group delay amount, which restricts the resolution of error correction and is influenced by cantilever resonance.
Innovation Solution
A vibration rectification error correction device that includes a frequency delta-sigma modulation circuit and filters synchronized with measured and reference signals, generating signals with different group delay amounts to cancel opposing vibration rectification errors, improving correction resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the group delay amount of the first low-pass filter is adjusted to correct vibration rectification error, then the vibration rectification error is reduced, but the correction resolution is limited by the period of the output signal of the physical quantity sensor
Solution Approach 1:
The patent introduces a frequency delta-sigma modulation circuit as an intermediary between the first low-pass filter and the second low-pass filter. This modulation circuit converts the measured signal into a frequency-modulated signal, allowing the first filter to operate at a different frequency than the original sensor output. This frequency transformation enables finer adjustment of the group delay amount, thereby improving the correction resolution of vibration rectification error without being constrained by the original signal period.
2Measurement precision
If a single low-pass filter is used for signal processing, then the device structure is simple, but the vibration rectification error correction resolution is insufficient
Solution Approach 1:
The patent divides the signal processing function into two separate low-pass filters with different operating characteristics. The first low-pass filter operates in synchronization with the measured signal to provide initial filtering and group delay adjustment, while the second low-pass filter operates in synchronization with a reference clock to perform final resampling and output. This segmentation allows each filter to be optimized for its specific function, achieving high correction resolution without requiring an overly complex single-filter design.
3Ease of manufacture
If the first low-pass filter operates in synchronization with the measured signal, then the filtering is simple to implement, but the correction resolution is limited by the signal period
Solution Approach 1:
The patent changes the operating parameter of the first low-pass filter from direct synchronization with the measured signal frequency to synchronization with a frequency delta-sigma modulated signal. This parameter change allows the filter to operate at a different frequency point, enabling finer control over the group delay amount. The frequency transformation through delta-sigma modulation effectively decouples the filter's operating frequency from the original signal period, thereby improving adjustment resolution while maintaining implementation simplicity.
Data Source
AI summary
A vibration rectification error correction device includes a first filter that operates in synchronization with the measured signal, and a second filter that operates in synchronization with the reference signal, in which the first filter generates a third signal based on a first signal having a first group delay amount and a second signal having a second group delay amount, the second filter receives a signal based on the third signal and outputs a fourth signal, and a first vibration rectification error and a second vibration rectification error have different polarities.