Infrasound Device Using Displacement Feedback to Reduce Harmonic Distortion
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Solution Overview
Problem
Existing infrasound generating devices suffer from large harmonic distortion, which affects the calibration accuracy of infrasonic sensors, as they rely on motor or vibrator-driven pistons to produce sinusoidal infrasonic pressure signals.
Innovation Solution
An infrasound generating device utilizing a displacement-feedback type vibration exciter system, which includes a signal generator, power amplifier, vibration exciter, and displacement-feedback component, along with a laser vibrometer to measure and correct displacement, reducing harmonic distortion by precisely following a standard signal and generating infrasonic pressure signals with low distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a motor or vibrator drives the piston to reciprocate and generate sinusoidal infrasonic pressure signals, then the infrasonic pressure signal can be produced, but the harmonic distortion of the generated signal is large due to nonlinear parameters
Solution Approach 1:
The patent employs a displacement-feedback control mechanism where a displacement sensor measures the actual displacement of the vibration exciter, and a controller compares this with the standard signal to generate a correction signal. This feedback loop continuously adjusts the exciter's operation to eliminate harmonic distortion, ensuring the output displacement precisely follows the standard sinusoidal signal. The feedback principle directly addresses the harmonic distortion issue by using real-time measurement and correction.
Solution Approach 2:
The patent replaces the traditional mechanical drive system with a displacement-feedback controlled vibration exciter system. Instead of relying on mechanical motors or vibrators that inherently produce harmonic distortion due to nonlinear parameters, the system uses an exciter whose displacement is actively controlled and corrected through feedback, substituting the mechanical generation approach with a controlled vibration approach that eliminates distortion.
2Measurement precision
If a displacement-feedback type vibration exciter is used to reduce harmonic distortion, then the calibration accuracy is improved, but the device complexity increases due to additional sensors and control components
Solution Approach 1:
The feedback mechanism uses a displacement sensor to measure the exciter's displacement and feeds this information back to the controller, which adjusts the exciter accordingly. This closed-loop control system, while adding components, provides precise displacement measurement and control, ensuring the exciter follows the standard signal accurately and minimizes harmonic distortion in the output.
Solution Approach 2:
The patent replaces complex mechanical measurement and control systems with a displacement-feedback controlled vibration exciter system. By using an exciter whose displacement can be precisely measured and controlled through feedback, the system achieves high measurement precision without requiring complex mechanical measurement apparatus, simplifying the overall system architecture while maintaining accuracy.
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
The device achieves high calibration accuracy for infrasonic sensors by minimizing harmonic distortion in the infrasonic pressure signals, ensuring precise calibration through the use of a displacement-feedback type vibration exciter and airtight infrasound generating chamber.
Implementation Method 1
a laser vibrometer measuring the vibration displacement of the vibration exciter
Implementation Method 2
a displacement sensor measuring the displacement of the moving part of the vibration exciter
Implementation Method 3
the vibration exciter drives the piston to move in a sinusoidal manner in the airtight infrasound generating chamber
Implementation Method 4
the movement of the piston results in the generation of the pressure wave
Data Source
AI summary
The infrasound generating device based on a displacement-feedback type vibration exciter comprises a displacement-feedback type vibration exciter system, an infrasound generating chamber (3) and a laser vibrometer (1); the displacement feedback mechanism is adopted in the vibration exciter (2). The piston (31) is driven by the vibration exciter to move in a sinusoidal manner in the cavity (35) of the airtight infrasound generating chamber (3) and the standard infrasonic pressure signal with low harmonic distortion can be achieved. The displacement of the moving part (22) of the vibration exciter (2) can be measured by the laser vibrometer (1) through the measurement beam (15) injecting into the vibration exciter (2) through the optical channel running through the vibration exciter and the standard infrasonic pressure can also be obtained. The value of the standard sound pressure produced by the infrasound generating chamber is calculated. Such value is used as the calibration reference for the infrasound sensors (4) to be calibrated in order to achieve the primary calibration of the infrasound sensors. The standard infrasonic sensor can be installed inside the infrasound generating chamber (3) and the output of the standard infrasonic sensor can be used as the reference for the infrasonic sensor (4) to be calibrated in order to achieve the secondary calibration of the infrasound sensors. This invention has the advantages of technical maturity, high feasibility, easy to realize, high calibration accuracy and so on.