Closed-Loop Filter Frequency Adaptation via Symmetric Noise Spectra
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Solution Overview
Problem
Existing rotation rate sensors face challenges in maintaining precise frequency matching between the secondary resonant frequency of the sensor and the primary resonant frequency, especially under temperature changes and production fluctuations, which affects signal-to-noise ratio and stability, particularly when operating in closed control loops.
Innovation Solution
A method that involves feeding the output signal of a delta sigma modulator into a frequency adaptation circuit to determine noise spectra in symmetric frequency bands, comparing these spectra, and generating an adaptation signal to adjust the secondary resonant frequency using the spring softening effect, allowing for continuous adaptation during operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resonant frequency of the secondary mass is adapted using existing methods, then the frequency matching is improved, but the adaptation requires discontinuous operation or additional signal processing that increases device complexity
Solution Approach 1:
The patent extracts only the necessary noise spectrum information from the output signal of the delta-sigma modulator, specifically comparing noise levels in frequency bands above and below the resonant frequency. This selective extraction avoids complex full-spectrum analysis while achieving accurate frequency adaptation.
Solution Approach 2:
The system uses its own output signal from the delta-sigma modulator to perform self-diagnosis and automatic frequency adaptation. The noise spectrum comparison is performed on signals already present in the system, eliminating the need for external test signals or additional measurement equipment.
2Measurement precision
If existing frequency adaptation methods are used, then frequency matching is achieved, but the adaptation process disrupts signal readout or requires additional space
Solution Approach 1:
The patent enables continuous frequency adaptation during normal sensor operation. The noise spectrum comparison is performed on the ongoing output signal from the delta-sigma modulator without interrupting the measurement process or requiring the system to exit closed-loop operation.
Solution Approach 2:
The output signal of the delta-sigma modulator serves multiple functions: it provides the measurement output and simultaneously serves as the source for frequency adaptation through noise spectrum analysis. This multi-functionality eliminates the need for separate test signal paths or additional hardware.
3Device complexity
If the resonant frequency is not continuously adapted, then the device structure remains simple, but temperature changes and production fluctuations cause frequency drift affecting signal-to-noise ratio
Solution Approach 1:
The patent implements a feedback mechanism where the noise spectrum comparison result automatically adjusts the resonant frequency of the second-order system. The adaptation signal is fed back to the filter to continuously correct frequency drift caused by temperature changes and production variations, maintaining optimal signal-to-noise ratio.
Solution Approach 2:
The system dynamically changes the resonant frequency parameter of the second-order system based on real-time noise spectrum analysis. By adjusting this critical parameter in response to environmental conditions, the system maintains optimal performance without requiring complex structural changes.
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 enables accurate and rapid frequency adaptation with minimal space requirements, maintaining high signal-to-noise ratio and stability without disrupting the signal readout, and can be applied to various sensors and filters.
Implementation Method 1
determining a first noise spectrum of the output signal in a first frequency band and a second noise spectrum of the output signal in a second frequency band
Implementation Method 2
generating an adaptation signal to adjust the secondary resonant frequency using the spring softening effect
Implementation Method 3
feeding an output signal of a delta sigma modulator of the closed control loop into a frequency adaptation circuit
Data Source
AI summary
A method adapts a resonant frequency of a first filter of a closed control loop to a given frequency. The method includes feeding an output signal of a delta sigma modulator of the closed control loop into a frequency adaptation circuit and determining a first noise spectrum of the output signal in a first frequency band and a second noise spectrum of the output signal in a second frequency band. The first frequency band and the second frequency band are arranged symmetrically with respect to the given frequency. The method includes comparing the first noise spectrum with the second noise spectrum, generating an adaptation signal that causes a frequency adaptation of the resonant frequency if the first noise spectrum differs from the second noise spectrum, and outputting the adaptation signal from the frequency adaptation circuit to a control input of the first filter for adapting the resonant frequency.