Transit Time Distance Sensor with Image Verification

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Solution Overview

Problem

Existing methods for securing danger areas in automated systems using transit time measurement are prone to errors due to ambiguities and require complex calibration, leading to unreliable distance determination and potential safety issues.

Innovation Solution

A device and method that record at least two images of a spatial area, with one image containing distance information from transit time measurement, and a test device checks for consistency between the two images to verify distance values, initiating error handling and triggering safety functions if discrepancies are found, thereby ensuring accurate distance measurement and increased reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If transit time measurement is used for distance determination, then the measurement process is simplified, but measurement precision deteriorates due to ambiguities and errors

Engineering Contradiction:
Improvemeasurement process complexityVSAvoiddistance measurement precision
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent uses a feedback mechanism where the first image recording unit captures images at two different points in time, and the evaluation unit compares these images to detect changes in the monitored area. This feedback loop allows the system to identify and correct erroneous distance measurements by verifying consistency across multiple measurements, thereby resolving ambiguities while maintaining a relatively simple transit time measurement approach.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent performs preliminary actions by capturing a first image before a potential hazard event and then capturing a second image after the event. By having these preliminary images ready for comparison, the system can quickly verify whether distance measurements are accurate without needing to perform complex real-time analysis during the actual measurement process.

Inventive Principle:
Principle #10Preliminary action

2Area of stationary object

If multiple light barriers are used to secure curved boundaries, then coverage area is improved, but device complexity increases

Engineering Contradiction:
Improvesecured area coverageVSAvoidnumber of light barriers
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The patent makes the single image recording unit universal by enabling it to perform multiple functions: it captures images for hazard detection, measures distances using transit time, and provides verification through temporal comparison. This multi-functional approach replaces the need for multiple specialized light barriers, allowing curved and complex boundary coverage while maintaining device simplicity.

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

Solution Approach 2:

The patent transitions from a one-dimensional approach (multiple linear light barriers) to a two-dimensional approach (single camera capturing entire areas). By imaging the entire monitored space rather than using multiple point-based light barriers, the system achieves comprehensive area coverage including curved boundaries with a single device.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Ease of operation

If image recording and evaluation is used instead of light barriers, then ease of operation is improved, but reliability deteriorates due to undetected errors

Engineering Contradiction:
Improvesystem setup easeVSAvoidsafety function reliability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent implements a feedback-based verification system where the evaluation unit compares images captured at different times to detect inconsistencies. This feedback mechanism automatically identifies erroneous distance measurements without requiring complex manual calibration or setup, thereby maintaining ease of operation while significantly improving reliability through automated error detection.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-verification by automatically comparing its own measurements across multiple images. The evaluation unit independently checks for consistency without external intervention, allowing the system to self-correct or self-flag erroneous measurements. This self-service approach enhances reliability while keeping the system easy to operate without requiring expert calibration.

Inventive Principle:
Principle #25Self-service

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 a cost-effective and reliable method for determining distances in automated systems, resolving ambiguities and ensuring fail-safe operation by simultaneously recording and processing multiple images, which enhances the accuracy and reduces unnecessary shutdowns.

Implementation Method 1

an image recording unit with an image sensor with a large number of pixels records an image of the room area by means of transit time measurement

Methodology Applied
Scientific EffectTransit time measurement: Time of Flight

Implementation Method 2

An image recording unit, which is aligned with a spatial area, images the area with the aid of a lighting device

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP1949143B1Apparatus and method for monitoring a zone of a room, particularly for securing a hazard area of an automatically operating system
Publication Date: 2018.10.31 PILZ GMBH & CO KG
  • EP1949143B1 patent drawingFigure 1
  • EP1949143B1 patent drawingFigure 2~3
  • EP1949143B1 patent drawingFigure 4~5

AI summary

Disclosed is an apparatus for monitoring a zone of a room, especially for securing a hazard area of an automatically operating system. Said apparatus comprises a lighting device which at least temporarily emits light signals into the zone of the room. A first image recording unit (22) is used for recording a first image of the zone of the room, said image recording unit (22) being equipped with an image sensor (26) with a plurality of pixels. An evaluation unit is configured so as to determine, by measuring the propagation time, a distance value (dM) for at least one point (34) that is located in the zone of the room and is reproduced onto at least one pixel. A test unit is configured so as to compare at least one first and a second image in order to recognize an incorrect distance value (dM).