Normal Vector Detection for Machining Tools

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Solution Overview

Problem

Existing normal detection methods for machining are inefficient in obtaining precise normal vectors on surfaces, requiring substantial time to align detection jigs and lacking precise control over machining directions, especially in complex structures like aircraft components.

Innovation Solution

A method using multiple distance detectors to calculate a normal vector by determining outer products of vectors formed from measurement points, with strategically selected measurement positions to maximize triangle area and employing non-contact sensors for precise, automatic posture control of machining tools.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If contact sensors are used to detect the normal vector by manually aligning the detection jig, then measurement precision can be achieved, but the detection time becomes substantially long and automatic control is difficult

Engineering Contradiction:
Improvenormal vector detection precisionVSAvoiddetection time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical contact sensor system with an optical non-contact sensor system. The normal detection device uses a non-contact sensor to measure distances to the workpiece surface, eliminating the need for manual alignment of contact sensors while maintaining measurement precision and enabling automatic control.

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

Solution Approach 2:

The detection device automatically determines its own posture relative to the workpiece surface by measuring distances at multiple points. The control unit calculates the normal vector based on these measurements, allowing the system to self-align without manual intervention, thereby reducing detection time while maintaining precision.

Inventive Principle:
Principle #25Self-service

2Device complexity

If a single height adjustment mechanism is used to align sensors with the machining tool, then device complexity is reduced, but the ability to detect perpendicularity in multiple directions is lost

Engineering Contradiction:
Improvealignment mechanism complexityVSAvoidmulti-directional perpendicularity detection
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the sensing function into multiple non-contact sensors positioned at different locations and orientations. Each sensor measures distances independently, allowing the system to detect surface geometry and calculate normal vectors in multiple directions without requiring complex mechanical alignment mechanisms.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent transitions from one-dimensional height adjustment to three-dimensional spatial measurement. By positioning non-contact sensors at multiple locations with different coordinates, the system can determine surface normals in three-dimensional space, enabling multi-directional perpendicularity detection without additional mechanical complexity.

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

3Measurement precision

If multiple distance measurements are taken at different positions to calculate the normal vector, then measurement precision is improved, but the computational complexity and device complexity increase

Engineering Contradiction:
Improvenormal vector calculation precisionVSAvoiddetection device structure
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The non-contact sensor serves multiple functions: it measures distances to determine surface geometry, calculates normal vectors through coordinate analysis, and provides data for posture control. This multi-functionality allows the system to achieve high measurement precision without proportionally increasing device complexity.

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

Solution Approach 2:

The control unit acts as an intermediary that processes distance measurements from multiple sensors and calculates the normal vector. This computational intermediary handles the complexity of multi-point measurements, allowing the physical detection device to remain relatively simple while achieving high measurement precision through software-based calculations.

Inventive Principle:
Principle #24Intermediary (Mediator)

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

Enables high-precision normal vector calculation and rapid alignment of machining tools, reducing operational time and improving machining accuracy even in complex geometries.

Implementation Method 1

a non-contact sensor 30 as the distance detector L is used

Methodology Applied
Scientific EffectOptical detection: Reflection

Data Source

PatentEP2827098B1Normal detection method, normal detection device, and machining machine provided with normal detection function
Publication Date: 2019.09.04 MITSUBISHI HEAVY IND LTD
  • EP2827098B1 patent drawingFigure 1
  • EP2827098B1 patent drawingFigure 2~3
  • EP2827098B1 patent drawingFigure 4~5

AI summary

A normal detection method for measuring the distance to a measurement subject (20) using one or more distance detectors (30), and obtaining a normal vector (Vn) on the measured surface (21) of the measurement subject (20) from the obtained measurement result (L), wherein: within a three-dimensional space, the straight line linking a first measurement point (Qa) measured at a first measurement position (Pa) using the distance detector (30) and a second measurement point (Qd) measured at a second measurement position (Pd) different from the first measurement position (Pa) is set as a first vector (Vad); the straight line linking the first measurement point (Qa) and a third measurement point (Qf) measured at a third measurement position (Pf) different from the first measurement position (Pa) and the second measurement position (Pd) as a second vector (Vaf); and a normal vector (Vn) on the measured surface (21) is obtained by determining the vector product of the first vector (Vad) and the second vector (Vaf).