Ultrasonic Sensor Blind Zone Reduction via Attenuator Circuit

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Solution Overview

Problem

Ultrasonic sensors face a blind zone issue due to residual mechanical vibration of the transducer, where reverberation signals obscure echo signals, making it difficult to detect objects within this zone, and existing solutions either avoid detection or increase production costs.

Innovation Solution

An ultrasonic sensing system with an attenuator circuit connected to the receiver via a switch, controlled by a microcontroller unit (MCU), which attenuates reverberation signals during the blind zone period to reduce interference, allowing for detection of objects within the previously undetectable zone without increasing production costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the ultrasonic transducer vibrates at high frequency to generate ultrasonic signals, then the sensing capability is improved, but residual mechanical vibration creates reverberation signals that obscure echo signals, forming a blind zone

Engineering Contradiction:

Improvedistance detection accuracyVSAvoidreverberation signals

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent extracts and removes the harmful reverberation signals from the detection path by using a band-stop filter tuned to the ultrasonic transmission frequency. This filter specifically eliminates the reverberation components while preserving the echo signals, thereby removing the blind zone without affecting the measurement precision.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary signal processing stage between the ultrasonic receiver and the detection system. This intermediary includes a band-stop filter that selectively removes reverberation frequencies and a gain-adjustable amplifier that compensates for signal attenuation, allowing clear detection of echo signals within the previously blind zone.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If the receiver probe is padded or protected using physical barriers to reduce reverberation, then the blind zone is reduced, but the manufacturing complexity and cost increase

Engineering Contradiction:

Improveblind zone reductionVSAvoidproduction cost

Core Design Contradiction:

Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the mechanical approach (physical barriers and padding) with an electronic signal processing approach. By using a band-stop filter and gain-adjustable amplifier in the electrical domain, the system achieves blind zone reduction without adding mechanical complexity or increasing manufacturing cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If detection is disabled during the blind zone period to avoid false detection, then reverberation interference is avoided, but objects within the blind zone cannot be detected

Engineering Contradiction:

Improvedetection accuracyVSAvoidminimum detection distance

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The patent applies local quality by selectively filtering only the specific frequency range corresponding to reverberation signals while leaving other frequencies intact. The band-stop filter targets only the ultrasonic transmission frequency, allowing echo signals at different frequencies to pass through, thereby enabling detection within the blind zone while maintaining detection reliability.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent employs dynamic gain adjustment through a gain-adjustable amplifier that adapts its amplification factor based on the detected signal characteristics. This dynamic adjustment allows the system to enhance weak echo signals from close objects while suppressing residual reverberation, enabling reliable detection within the blind zone.

Inventive Principle:

Principle #15Dynamics

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 system effectively reduces or eliminates the blind zone, enabling the detection of objects closer to the sensor by distinguishing between reverberation and echo signals, thus enhancing the minimum measurable distance without increasing production costs.

Implementation Method 1

a pulse of electrical energy can cause a piezoelectric transducer to vibrate at a given frequency due to piezoelectricity, thereby generating an ultrasonic sound wave

Methodology Applied

Scientific EffectPiezoelectricity: Piezoelectric Effect

Implementation Method 2

Ultrasonic transducers are typically configured to generate ultrasonic signals by high frequency vibrations or resonance caused by an excitation signal

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 3

the attenuator circuit operable for eliminating substantially all of the reverberation signals without eliminating the echo signals

Methodology Applied

Scientific EffectSignal attenuation: Absorption (physical)

Data Source

PatentUS10852130B2Proximity sensing systems and methods

Publication Date: 2020.12.01 SZ DJI TECH CO LTD

AI summary

An ultrasonic sensing system includes an ultrasonic receiver configured to receive an ultrasonic signal and a gain-adjustable amplifier operably coupled to the ultrasonic receiver. The gain-adjustable amplifier is configured to amplify the ultrasonic signal according to a variable gain determined based at least in part on a value of a timer that corresponds to a measuring distance.