Optoelectronic Sensor Multiple Scanning Beams Edge Detection

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Solution Overview

Problem

Conventional laser scanners face challenges in accurately measuring object distances, particularly at edges and small objects, due to the averaging method which results in smeared and unreliable measurements, especially when using a rotating mirror or multiple scanning beams.

Innovation Solution

The use of multiple scanning beams with a control and evaluation unit that offsets individual measurements from different beams to form a common measured value, reducing spatial blurring and improving measurement accuracy by ensuring that each object point is hit by multiple beams, thereby enhancing the precision of edge hits and small object detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of stationary object

If a pulse averaging method is used to increase measurement range with limited light pulse energy, then the measurement range is improved, but the measurement precision deteriorates due to spatial blurring and smeared measured values

Engineering Contradiction:
Improvemeasurement rangeVSAvoidmeasurement precision
Core Design Contradiction:
Length of stationary objectVSMeasurement precision

Solution Approach 1:

The patent divides the measurement task into multiple independent scanning beams instead of using a single scanning beam with pulse averaging. Each scanning beam performs individual measurements at its specific angular position, eliminating the spatial blurring effect that occurs when multiple pulses are averaged at different positions. This segmentation allows the system to maintain both extended measurement range through multiple beams and high precision by avoiding temporal-spatial mixing of measurements.

Inventive Principle:
Principle #1Segmentation

2Length of stationary object

If multiple light pulses are emitted for each distance value to increase range, then the measurement range is improved, but the reliability deteriorates due to missing or incorrect measured values at edges

Engineering Contradiction:
Improvemeasurement rangeVSAvoidreliability
Core Design Contradiction:
Length of stationary objectVSReliability

Solution Approach 1:

By segmenting the measurement into multiple simultaneous scanning beams, the patent ensures that edge detections are performed by dedicated beams at their respective angular positions rather than being averaged with other positions. This segmentation prevents the loss of edge information that occurs in pulse averaging methods, thereby maintaining high reliability while extending measurement range.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from a temporal averaging approach (multiple pulses at one position) to a spatial parallel approach (multiple beams at multiple positions). This dimensional change from time to space allows simultaneous coverage of multiple angular positions without the temporal-spatial mixing that causes unreliable edge measurements in conventional pulse averaging methods.

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

3Device complexity

If a single scanning beam is used to simplify the system, then the device complexity is reduced, but the productivity deteriorates due to limited scanning coverage

Engineering Contradiction:
Improvedevice complexityVSAvoidscanning coverage
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The patent segments the light source into multiple independent scanning beams that operate simultaneously. This segmentation enables the system to cover multiple angular positions and scanning planes in parallel, significantly increasing productivity and scanning coverage while maintaining relatively simple device architecture through the use of multiple independent but identical beam paths.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent combines multiple scanning beams to achieve comprehensive scanning coverage. By merging the capabilities of multiple beams operating in parallel, the system attains extended angular coverage and improved productivity while keeping individual beam components simple and manageable.

Inventive Principle:
Principle #5Merging (Combining)

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 significantly improves measurement accuracy and reliability by reducing spatial blurring, allowing for precise detection of edges and small objects without compromising motor frequency or optical light output, and potentially extending the service life of light sources.

Implementation Method 1

The distance of the object from the laser scanner is also determined from the travel time of light using the speed of light in a phase or pulse method

Methodology Applied
Scientific EffectTime of flight: Time of Flight

Implementation Method 2

The light is remitted to objects in the surveillance area

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

a light beam generated by a laser periodically scans a surveillance area with the help of a deflection unit

Methodology Applied
Scientific EffectLight deflection:

Data Source

PatentEP3712647B1Optoelectronic sensor and method for detecting objects
Publication Date: 2021.04.28 SICK AG
  • EP3712647B1 patent drawingFigure 1
  • EP3712647B1 patent drawingFigure 2~3
  • EP3712647B1 patent drawingFigure 4~5

AI summary

An optoelectronic sensor (10) for detecting objects in a monitoring area (20) is specified, comprising a light transmitter (22) for emitting transmitted light (26), a movable deflection unit (12) for periodically deflecting the transmitted light (26), and a light receiver (32) for receiving the transmitted light (28) remitted by objects in the monitoring area (20), wherein the transmitted light (26) forms several separate scanning beams (26, 28) and/or the light receiver (32) receives the remitted transmitted light (28) as several separate scanning beams (26, 28), as well as a control and evaluation unit (40) which is configured to perform individual measurements with each scanning beam (26, 28) and to calculate several individual measurements to obtain a common measured value for the distance to the object.The control and evaluation unit (40) is further designed to combine individual measurements of at least two different scanning beams (26, 28) into a common measured value.