Rotating Tool Presence Detection Using Pulsed Laser and FFT Analysis

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Solution Overview

Problem

Existing methods for checking the presence of a rotating tool in numerical control machine tools face high risks of false positive and false negative errors due to noise interference in the analysis of reflected electromagnetic radiation, making it difficult to reliably determine if the tool is present and intact.

Innovation Solution

A checking apparatus that uses a pulsed laser beam to detect the rotating tool, collects reflected radiation, and processes it using a processing unit to determine the tool's presence by analyzing the length of the signal based on the rotational frequency, applying filtering and scaling, and performing a Fast Fourier Transform to identify harmonics corresponding to the tool's rotational frequency, thereby reducing noise interference and improving reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If complex processing is applied to analyze reflected electromagnetic radiation to avoid false positive errors, then reliability is improved, but device complexity increases and computational requirements increase

Engineering Contradiction:
Improvereliability in determining the presence of the rotating toolVSAvoidcomplexity of the checking apparatus
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts only the essential information from the reflected electromagnetic radiation signal by analyzing its temporal characteristics and rotational frequency components. Instead of processing the entire complex signal, the method isolates and examines specific features (signal presence, frequency matching) that are sufficient to determine tool presence, thereby reducing computational complexity while maintaining reliability

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent performs preliminary actions by first establishing the rotational frequency of the spindle and tool, then using this information to guide the analysis of reflected radiation. The system prepares reference frequency data and temporal patterns before analyzing the actual reflection signal, which simplifies the subsequent detection process and reduces the complexity of real-time processing requirements

Inventive Principle:
Principle #10Preliminary action

2Reliability

If contactless type checking apparatus is used to detect rotating tool, then reliability is improved, but overall dimensions increase

Engineering Contradiction:
Improveability to detect rotating tool without contactVSAvoidoverall dimensions of the checking apparatus
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The patent uses optical copying principles by directing electromagnetic radiation at the tool and analyzing the reflected pattern. The system creates an optical copy or representation of the tool's presence and rotational characteristics through the reflected radiation pattern, allowing detection without physical contact while keeping the apparatus compact by using standard optical components rather than large-scale measurement systems

Inventive Principle:
Principle #26Copying

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 method provides a quick and reliable way to determine the presence or absence of the rotating tool, reducing the risk of errors and requiring minimal computational power and memory, making it easily and cost-effectively implementable.

Implementation Method 1

a receiver which is arranged next to the emitter and receives the electromagnetic radiation reflected by the rotating tool

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2731754B1Method for checking the presence of a rotating element in a machine tool
Publication Date: 2018.10.17 MARPOSS SPA
  • EP2731754B1 patent drawingFigure 1
  • EP2731754B1 patent drawingFigure 2
  • EP2731754B1 patent drawingFigure 3

AI summary

Checking method and apparatus for checking the presence of a rotating element (3) at a known or determinable rotational frequency (RF); an emitter (8) directs a main electromagnetic radiation (9) towards the rotating element (3); a receiver (10) receives a reflected electromagnetic radiation (11) which has been reflected by the rotating element (3); and a processing unit (12) samples the reflected electromagnetic radiation (11) to determine a rough signal (S) to analyze, analyzes in the frequency domain the rough signal (S) to check whether the rough signal (S) includes a periodicity with a frequency corresponding to the rotational frequency (RF) of the rotating element (3), and determines that the rotating element (3) is actually present if the rough signal (S) includes a periodicity with a frequency corresponding to the rotational frequency (RF) of the rotating element (3).