Detection of irregularities in a convex surface, such as a tire sidewall, using band-pass filtering

US6539789B1 · kind B1 · utility

Assignee

• Fraunhofer-Gesellschaft zur förderung der angewandten Forschung e.V. · DE

Inventors

• Guenther Kostka · Erlangen, DE
• Peter Schmitt · Erlangen, DE
• Ulf Hassler · Heilsbronn, DE
• Randolf Hanke · Fürth, DE

Key dates

• Filing date: Jul 16, 2001
• Grant date: Apr 1, 2003
• Expiry date: Jul 16, 2021

Classification

• Technology area (CPC G): Physics
• CPC primary: G06T2207/30108
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A device for the contactless detection of a potentially existing essentially edge-free irregularity in a convex surface, which has a structuring that is delimited by edges, comprises a unit for creating a three-dimensional representation of the surface, a unit for extracting the convexity from the three-dimensional representation of the surface and for smoothing the edges of the structuring so as to obtain a convex-free representation of the convex surface which exhibits the irregularity and the structuring, whose edges have now been smoothed, a unit for comparing the convex-free representation with a threshold value so as to identify areal regions of the convex-free representation which are determined by a predetermined relationship to the threshold value, and a unit for analyzing the areas of the identified regions, a region being detected as an irregularity if its area exceeds a predetermined area. When this device is used to carry out quality control of tires, bulges or constrictions can therefore be identified with certainty in real-time operation and can be distinguished from an inscription or marking which has been intentionally provided on the tire.