Ultrasonic Sensor Frequency Tracking for Resonance Drift

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Solution Overview

Problem

Piezoelectric ultrasound detection devices operating continuously face challenges in maintaining their natural or resonance frequency due to fluctuations over their service life and temperature changes, making it difficult to achieve high accuracy without additional measures.

Innovation Solution

A method that automatically adjusts the operating frequency of an ultrasonic detection device by changing the control frequency based on the received signal strength, using an amplitude-based control loop to track resonance and account for long-term drift, with a slow control loop that repeatedly adjusts the frequency to maximize signal strength and detect disturbances in the transmission path.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the operating frequency is set statically during design, then the device complexity is reduced, but the measurement precision of the resonance frequency deteriorates due to fluctuations over service life and temperature changes

Engineering Contradiction:
Improvesystem design complexityVSAvoidresonance frequency accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic frequency adjustment mechanism that continuously adapts the operating frequency based on real-time resonance detection. The system repeatedly changes the control frequency and monitors received signal strength to track the resonance frequency drift over time and temperature variations, resolving the contradiction between static design simplicity and dynamic measurement precision.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent employs a feedback control loop where the received signal strength at the ultrasonic receiver is continuously monitored and used to adjust the control frequency of the transmitter. This closed-loop system detects resonance conditions and automatically corrects frequency deviations, maintaining high measurement precision without requiring complex design compromises.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If additional on-chip measures are implemented to maintain natural frequency, then the measurement precision improves, but the device complexity increases

Engineering Contradiction:
Improvenatural frequency maintenance accuracyVSAvoidon-chip measures complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a self-tuning mechanism where the ultrasound detection device automatically maintains its resonance frequency without requiring external intervention or complex on-chip hardware additions. The system uses its own received signal strength information to self-correct frequency deviations, achieving high precision while minimizing additional device complexity.

Inventive Principle:
Principle #25Self-service

3Measurement precision

If the control frequency is changed frequently to track resonance, then the measurement precision improves, but the loss of time increases due to continuous adjustment

Engineering Contradiction:
Improveresonance frequency tracking accuracyVSAvoidfrequency adjustment time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent implements a periodic frequency sweeping mechanism where the control frequency is changed in predetermined steps at optimized intervals. This periodic adjustment strategy maintains accurate resonance tracking while minimizing the time lost to frequency changes, balancing measurement precision with operational efficiency.

Inventive Principle:
Principle #19Periodic action

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 method ensures the ultrasonic system operates consistently at its resonance frequency, even with aging or temperature changes, by continuously adjusting the control frequency to maintain optimal signal strength and detect potential disturbances.

Implementation Method 1

piezoelectric ultrasound detection devices

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

piezoelectric ultrasound detection devices

Methodology Applied
Scientific EffectPiezoelectric effect: Converse Piezoelectric Effect

Implementation Method 3

Oscillating systems generally work most effectively when they are operated at their natural or resonant frequency

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP2725353B1Method for automatic operating frequency work point adjustment of an ultrasound detection device
Publication Date: 2017.07.19 ELMOS SEMICON AG
  • EP2725353B1 patent drawingFigure 1
  • EP2725353B1 patent drawingFigure 2
  • EP2725353B1 patent drawingFigure 3

AI summary

The method involves changing driving frequency of an ultrasonic sensor in intervals, where the driving frequency comprises different values during different set of intervals. The driving frequency is changed until reception signal strength reaches maximum or the driving frequency is changed in temporary consecutive intervals with alternating signs if the reception signal strength remains unchanged or the reception signal strength is changed with the alternating signs with which an operating point of an operation frequency of an ultrasound detection device is adjusted.