Surface Acoustic Wave Object Detection via Rayleigh Waves

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Solution Overview

Problem

Existing object detection methods in surveillance areas face limitations due to visual impairments, interference sources, and the inability to detect static objects that do not generate vibrations, making them inefficient and costly.

Innovation Solution

A device and method utilizing sound waves that propagate in solid surfaces, specifically exciting and detecting Rayleigh waves, which allow for the detection of objects by analyzing changes in measurement signals generated by the interaction of sound waves with the surface, using a sound source and pickup system with a control and evaluation device to determine object presence and position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cameras, laser scanners, radar or ultrasonic sensors are used for object detection, then detection capability is provided, but visual impairments such as fog, sources of interference such as the sun or other sources of radiation, and limitations (one object can cover another object) occur

Engineering Contradiction:
Improvedetection capabilityVSAvoidvisual impairments and interference
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces optical/electromagnetic detection systems (cameras, laser scanners, radar) with an acoustic-based detection system that uses sound wave propagation through solid surfaces (ground waves) to detect objects. This substitution eliminates dependence on visual conditions and electromagnetic radiation, providing reliable detection in environments with fog, sun interference, or radiation sources.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a solid surface (ground) as an intermediary medium for sound wave propagation. Instead of detecting objects directly through air or electromagnetic waves, the system uses sound waves traveling through the solid ground surface to indirectly detect objects, bypassing visual impairments and interference sources that affect traditional detection methods.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If pressure sensors are used to monitor an area, then object detection is possible, but each pressure sensor must be connected to a control and evaluation unit, which makes the installation of such a system expensive

Engineering Contradiction:
Improveobject detectionVSAvoidinstallation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent employs a single control and evaluation unit that serves multiple sound sensors, allowing the system to detect objects across a large area without requiring individual control units for each sensor. This multi-functional approach significantly reduces installation complexity and cost while maintaining comprehensive object detection capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent combines multiple sound sensors into a unified detection system with a single control and evaluation unit. By merging the sensing and evaluation functions into one centralized unit, the system achieves cost-effective installation while maintaining the ability to monitor entire rooms or large areas, contrasting with pressure sensor systems that require separate control units for each sensor.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If sensors are used to detect vibrations in the ground caused by steps, then the position of people can be determined, but static objects that do not cause vibrations cannot be detected

Engineering Contradiction:
Improveposition determinationVSAvoiddetection coverage
Core Design Contradiction:
Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent uses periodic sound wave emissions that continuously propagate through the ground surface, allowing the system to detect both moving objects (that disrupt the periodic wave pattern through vibrations) and static objects (that reflect or absorb the periodic waves). This periodic action enables comprehensive detection of all object types regardless of whether they generate vibrations.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent utilizes mechanical vibrations generated by sound waves traveling through the solid ground surface. These vibrations interact with both moving objects (through additional vibration generation) and static objects (through reflection and absorption), enabling the system to detect and determine the position of all objects regardless of their motion state, thereby increasing detection versatility.

Inventive Principle:
Principle #18Mechanical vibration

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 provides effective object detection with improved accuracy and immunity to interference, capable of detecting both moving and static objects without the need for extensive infrastructure, and can be combined with other sensing technologies.

Implementation Method 1

When sound propagates in a solid body, in contrast to sound propagation in gases or liquids, transverse waves and surface waves, in particular so-called Rayleigh waves, occur in addition to longitudinal waves

Methodology Applied
Scientific EffectRayleigh waves: Surface Acoustic Wave

Implementation Method 2

At least one sound pickup is designed to detect sound waves generated in the area and to generate measurement signals from the detected sound waves

Methodology Applied
Scientific EffectAcoustic wave detection: Sound

Implementation Method 3

The sound waves generated in this way can then be recorded and measurement signals can be generated from the recorded sound waves

Methodology Applied
Scientific EffectSound wave reflection: Reflection

Implementation Method 4

the reflected sound waves being able to interfere with one another and with the coupled sound waves

Methodology Applied
Scientific EffectWave interference: Interference

Data Source

PatentEP4134699A1Device and method for detecting objects in a surveillance area
Publication Date: 2023.02.15 SICK AG
  • EP4134699A1 patent drawingFigure 1~2
  • EP4134699A1 patent drawingFigure 3~4
  • EP4134699A1 patent drawing

AI summary

A device for detecting objects in a monitoring area is described, the monitoring area having at least one surface formed from at least one solid material. A sound source couples sound waves into the surface of the monitoring area. A sound sensor detects the sound waves generated in the surface and generates measurement signals from them. A control and evaluation unit controls the sound source and receives the measurement signals from the sound sensor, enabling the control and evaluation unit to detect the presence of an object on the surface of the monitoring area based on these measurement signals.