Resonance Frequency Measurement Device for String Tensometric Sensors
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Solution Overview
Problem
Current excitation systems for tensometric sensors have limitations in adapting to varied sensor types, leading to suboptimal excitation and measurement errors due to fixed gain and narrow-band filtering, which can result in overexcitation or insufficient signal, and are slow in responding to resonance frequency changes.
Innovation Solution
A device with a microprocessor-controlled system that uses spectral analysis for initial resonance frequency determination, adjusts excitation parameters, and employs a tunable differential amplifier and SC filter to optimize excitation, eliminating the need for phase-locked loops and slow-tuning generators, allowing for flexible and efficient excitation of a wide range of sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed gain amplifiers and filters are used in the signal path, then the device structure is simplified, but the excitation cannot adapt to varied sensor types leading to measurement errors
Solution Approach 1:
The patent implements variable gain amplifiers and tunable filters that can dynamically adjust their parameters based on the specific sensor type being measured. This allows the device to adapt to different sensor characteristics while maintaining a relatively simple overall structure, resolving the contradiction between structural simplicity and adaptability.
Solution Approach 2:
The invention changes the parameters of amplifiers and filters from fixed to variable/tunable. By allowing gain and filter characteristics to be adjusted according to different sensor types, the system achieves versatility without requiring completely different hardware configurations for each sensor type.
2Device complexity
If constant level excitation is used, then the excitation circuit is simple, but the signal may be saturated or insufficient leading to measurement errors
Solution Approach 1:
The excitation circuit uses variable amplitude capability that allows the excitation signal level to be dynamically adjusted. This prevents signal saturation in high-coupling sensors while providing sufficient excitation for low-coupling sensors, improving measurement precision without requiring complex circuitry.
Solution Approach 2:
The system incorporates feedback mechanisms that monitor the signal quality and adjust the excitation amplitude accordingly. This feedback control ensures optimal signal levels are maintained across different sensor types, preventing both saturation and insufficient signal conditions.
3Stability of the object's composition
If slow-tuning generator is used to search for resonance frequency, then the system is stable, but the response speed is slow
Solution Approach 1:
The patent uses spectral analysis to preliminarily determine the resonance frequency before detailed measurement. This preliminary action allows the system to quickly identify the approximate resonance frequency and then fine-tune from there, significantly reducing the overall response time while maintaining stability.
Solution Approach 2:
The invention replaces the mechanical slow-tuning generator approach with spectral analysis and microprocessor-based frequency determination. This substitution of measurement techniques enables much faster identification of resonance frequency while maintaining system stability through digital control.
4Ease of manufacture
If dedicated manufacturer exciters with fixed parameters are used, then the device is simple to manufacture, but it cannot be used for all sensor types
Solution Approach 1:
The patent designs a universal exciter and measurement system that can handle multiple sensor types through software control and parameter adjustment. Rather than manufacturing different hardware exciters for each sensor type, the system uses a single versatile platform that adapts to different sensors, simplifying manufacturing while maximizing compatibility.
Solution Approach 2:
The invention enables parameter changes in the excitation and measurement circuits to accommodate different sensor types. By making key parameters adjustable rather than fixed, the system achieves broad sensor compatibility while maintaining a standardized manufacturing process for the core device.
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 solution enables faster and more accurate measurement of resonance frequencies by optimizing excitation for various sensor types, reducing measurement errors and improving system responsiveness.
Implementation Method 1
the string oscillations are excited by a pulse in an excitation coil
Implementation Method 2
the voltage generated in the coil by tail oscillations is measured
Data Source
Figure 1
Figure 2
AI summary
The system works on the principle of measuring the damped oscillations of sensors with synchronized excitation. Excitation pulses are generated by the processor (12), which in response to the properties of the connected sensor (2) adjusts their amplitude, number, period and rate. The processor (12) controls also the entire behavior of the system, thus considerably enhancing its flexibility. Based on the measured excitation rate and the level of the induced voltage during tail oscillations of the string the processor (12) sets also the corresponding gain of the differential amplifier (4) and tunes the narrow-band amplifying SC filter (6). This allows the system to efficiently excite and identify vast range of various sensor types. Initial searching of the resonance frequency in the non-synchronized state is based on the frequency analysis performed also by the processor (12) upon recorded pulse response of the sensor (2). The exciter (1) itself is enhanced with the current protection against short circuit. Due to the bridge structure of the exciter (1) it is possible to efficiently excite the sensor (2) and to design the subsequent input amplifier of the induced voltage as a differential amplifier (4), which amplifies the useful induced signal while suppressing the common interference.