Surface Texture Assessment Using FFT for Coating Defect Control

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Solution Overview

Problem

Existing coating compositions for automotive body panels face challenges in achieving optimal visual appearance and durability, with issues such as sagging on vertically oriented surfaces and orange peel on horizontally oriented surfaces, making it difficult to produce smooth, glossy coatings.

Innovation Solution

A computer-implemented method and system that assesses and controls the texture of surfaces by projecting a predefined line pattern, processing image data using pattern recognition and fast Fourier transformation to derive texture parameters, allowing for real-time monitoring and adjustment of production parameters to achieve desired surface texture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If higher clearcoat film build is applied to achieve desired visual appearance and durability, then gloss and smoothness are improved, but sagging tendency increases on vertically oriented surfaces

Engineering Contradiction:
Improvevisual appearance qualityVSAvoidsagging
Core Design Contradiction:
Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the texture of the coated surface is measured using a line pattern projection system, and the measured texture parameters are fed back to control the coating application process. This allows real-time adjustment of coating parameters to maintain optimal film build while preventing sagging on vertical surfaces.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes physical parameters of the coating system, including film build thickness, coating composition ratios, and application parameters, to optimize the balance between achieving high gloss and smoothness while maintaining sag resistance on vertically oriented surfaces.

Inventive Principle:
Principle #35Parameter changes

2Object-generated harmful factors

If clearcoat composition is formulated to resist sagging on vertical surfaces, then sagging is reduced, but orange peel and surface irregularities increase on horizontally oriented surfaces

Engineering Contradiction:
Improvesagging resistanceVSAvoidsurface smoothness
Core Design Contradiction:
Object-generated harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies different coating formulations and parameters to different surface orientations (vertical vs. horizontal) to achieve optimal performance for each. The line pattern measurement system enables detection of orientation-specific texture issues, allowing localized optimization of coating properties.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The measurement system provides feedback on surface texture characteristics, enabling real-time adjustment of coating parameters to prevent orange peel and surface irregularities on horizontal surfaces while maintaining sag resistance on vertical surfaces.

Inventive Principle:
Principle #23Feedback

3Manufacturing precision

If conventional coating application methods are used to achieve high film build, then visual appearance is improved, but production efficiency decreases due to multiple trial runs

Engineering Contradiction:
Improvecoating qualityVSAvoidproduction efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent performs preliminary measurement and assessment of surface texture during the coating process using the line pattern projection system. This allows real-time detection and correction of coating issues, eliminating the need for multiple trial runs and reducing production time while maintaining high coating quality.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The real-time feedback mechanism provided by the texture measurement system enables immediate adjustment of coating parameters during application, ensuring consistent high-quality results without requiring repeated trial runs and significantly improving production efficiency.

Inventive Principle:
Principle #23Feedback

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 efficient production of coated objects with the desired texture by optimizing the coating process, reducing sagging and orange peel defects, and ensuring high gloss and smoothness.

Implementation Method 1

calculating a wavelength spectrum of each formed concatenated line by means of a fast Fourier transformation

Methodology Applied
Scientific EffectFast Fourier transformation:

Implementation Method 2

extracting a plurality of parallel lines from the processed image data using a pattern recognition algorithm

Methodology Applied
Scientific EffectPattern recognition:

Implementation Method 3

A surface reflects an incident light into eyes of an observer causing a visual impression of the object

Methodology Applied
Scientific EffectLight reflection: Reflection

Data Source

PatentEP4256510B1A method and a system for assessing and optionally monitoring or controlling the texture of a surface
Publication Date: 2026.03.04 BASF COATINGS GMBH
  • EP4256510B1 patent drawingFigure 1
  • EP4256510B1 patent drawingFigure 2~4
  • EP4256510B1 patent drawingFigure 5~9

AI summary

The invention relates to a computer-implemented method for assessing and optionally monitoring or controlling a texture of a surface, comprising the steps of providing via an input channel to a processing device image data of a surface, deriving at least one texture parameter of the surface from the provided image data by extracting a plurality of parallel lines from the processed image data using a pattern recognition algorithm, concatenating at least two extracted parallel lines and calculating a wavelength spectrum of each formed concatenated line by means of a fast Fourier transformation, and providing the at least one texture parameter via an output channel. Furthermore, the invention relates to a system comprising an input channel connected to a processing device, a processing device configured to derive and optionally monitor or control the at least one texture parameter of the surface, an output device and optionally at least on surface preparation device. Finally, the invention relates to a computer program product for assessing and optionally monitoring or controlling a texture of a surface, comprising a data carrier storing a program code to be executed by a processor.