3D Measuring Device Retroreflective Target Detection

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Solution Overview

Problem

Existing three-dimensional measuring devices face inefficiencies in recognizing targets due to the need for repeated adjustments of light quantity and scanning operations, leading to prolonged processing times and potential false recognition.

Innovation Solution

A three-dimensional measuring device that uses a light source unit for distance measuring light, an illumination light source unit with multiple wavelengths, and an image pickup unit sensitive to blue, green, and red, which acquires difference images to detect retroreflective targets based on light intensity distribution and hue, eliminating the need for scanning and improving detection accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If scanning operations and repeated adjustments of light quantity are performed to detect targets, then detection accuracy is improved, but processing time increases and productivity decreases

Engineering Contradiction:
Improvedetection accuracyVSAvoidprocessing time
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent applies preliminary action by pre-segmenting the measurement area into multiple regions before actual measurement begins. This allows the system to quickly identify which regions contain targets and focus measurement resources only on those areas, eliminating the need for repeated scanning adjustments and significantly reducing processing time while maintaining detection accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent divides the measurement area into multiple segmented regions, enabling parallel processing of different areas. This segmentation strategy allows the system to simultaneously analyze multiple regions without requiring sequential scanning adjustments, thereby improving productivity while preserving measurement precision through dedicated analysis of each segment.

Inventive Principle:
Principle #1Segmentation

2Measurement precision

If scanning operations are performed to detect targets, then detection accuracy is improved, but device complexity increases

Engineering Contradiction:
Improvedetection accuracyVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces mechanical scanning operations with an image processing-based detection system. Instead of using complex mechanical scanning mechanisms to detect targets, the system captures images and processes them computationally to identify target locations and characteristics, thereby reducing device complexity while maintaining or improving detection accuracy.

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

Solution Approach 2:

The patent uses image copying and processing to create a digital representation of the measurement area. By working with image data rather than direct optical scanning, the system simplifies the physical device requirements while enabling accurate target detection through computational analysis of the captured images.

Inventive Principle:
Principle #26Copying

3Measurement precision

If repeated adjustments of light quantity are performed to discriminate retroreflective objects, then detection accuracy is improved, but loss of time increases

Engineering Contradiction:
Improvedetection accuracyVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent changes the parameter approach by using image processing algorithms that can directly analyze light intensity distributions and hue information from captured images. This eliminates the need for repeated adjustments of light quantity, as the system can process a single image capture to accurately discriminate retroreflective objects based on their optical characteristics, thereby reducing measurement time while maintaining detection accuracy.

Inventive Principle:
Principle #35Parameter changes

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 solution reduces processing time, enhances detection efficiency, and prevents false recognition by accurately identifying targets through image processing, thereby simplifying the device and reducing manufacturing costs.

Implementation Method 1

a light receiving element for converting the reflected light condensed by the light receiving optical unit into an electric signal

Methodology Applied
Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

a target with retroreflective ability (e. g., a reflective sheeting) is employed, and by detecting a reflected light from the target (detecting a light spot)

Methodology Applied
Scientific EffectRetroreflection: Retroreflector

Data Source

PatentEP2722645B1Three-dimensional measuring device and three-dimensional measuring system
Publication Date: 2018.05.09 TOPCON CORPORATION
  • EP2722645B1 patent drawingFigure 1
  • EP2722645B1 patent drawingFigure 2
  • EP2722645B1 patent drawingFigure 3

AI summary

A three-dimensional measuring device includes a light source unit 37 for generating a distance measuring light 8, a light projecting optical unit 39 for projecting the distance measuring light from the light source unit on a distance measuring optical axis 42, a light receiving optical unit 46 for receiving a reflected light from an object to be measured, a light receiving element 49 for converting the reflected light condensed by the light receiving optical unit into an electric signal, a scanning unit 36 for scanning the distance measuring light over the object to be measured, an angle detector 19, 23 for detecting an projecting direction of the distance measuring light scanned by the scanning unit, an illumination light source unit 51 for projecting an illumination light having a plurality of wavelengths, an image pickup unit 29 for acquiring two-dimensional images of the plurality of wavelengths and a control arithmetic unit 31, wherein the control arithmetic unit comprises a distance data processing unit for controlling a drive of the scanning unit, for calculating a distance to the object to be measured based on a received light signal from the light receiving element, and for calculating a three-dimensional data of the object to be measured based on a calculated distance and a detection signal from the angle detector and an image data processing unit for acquiring an image illuminated with the illumination light source unit and an unilluminated image by the image pickup unit, for acquiring a difference image based on both images, for detecting a retroreflective target based on the difference image and a detected intensity of a reflected light having a plurality of wavelengths detected from the difference image, and for calculating a position of the target.