Tyre Inspection Apparatus with Pre-Alignment Centring
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Solution Overview
Problem
Existing methods for checking vehicle tires rely on a posteriori correction of misalignment between the tire and rotating table, which can lead to inaccurate image acquisition due to limited depth of field and field of view, especially in plants producing diverse tire models, risking collisions and compromising the accuracy and reliability of defect detection.
Innovation Solution
A method and apparatus that align the tire's axis of rotation with the rotating table's axis prior to image acquisition by estimating the tire's center using a side view image and processing it to determine the cumulative probability distribution of potential axes of symmetry, ensuring precise alignment and accurate image focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a posteriori correction of misalignment is used, then the system can handle diverse tire models, but image acquisition accuracy deteriorates due to limited depth of field and field of view
Solution Approach 1:
The patent applies preliminary action by performing alignment of the tire's axis of rotation with the rotating table's axis before image acquisition begins. The system estimates the tire's center position and adjusts the rotating table's axis accordingly in advance, ensuring that the tire remains properly positioned within the camera's depth of field and field of view throughout the inspection process, thereby maintaining high image acquisition accuracy for diverse tire models
2Adaptability or versatility
If a posteriori correction of misalignment is used, then the system can operate with diverse tire models, but reliability deteriorates due to risk of collisions
Solution Approach 1:
The system performs preliminary alignment by estimating the tire's center position and adjusting the rotating table's axis before the inspection process begins. This advance positioning ensures that the tire remains within the safe operational envelope throughout rotation, eliminating the risk of collisions with the camera or other inspection equipment, thereby improving system reliability for diverse tire models
3Adaptability or versatility
If a posteriori correction of misalignment is used, then the system can process diverse tire models, but detection accuracy deteriorates due to out-of-focus images
Solution Approach 1:
The patent applies preliminary action by aligning the tire's rotation axis with the rotating table's axis before image acquisition. This ensures that the entire tire surface remains within the camera's depth of field throughout the inspection process, producing consistently in-focus images that enable accurate defect detection for diverse tire models without requiring post-acquisition refocusing
Data Source
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AI summary
Method and apparatus (18) for checking tyres (2) for vehicle wheels wherein it is provided to: feed a tyre (2) to be checked to a checking station (27) with a sidewall (11 ) of the tyre (2) laid on a supporting portion (36) of a rotating table (35), wherein the supporting portion (36) lies on a plane and the rotating table (35) has an axis of rotation (Z) perpendicular to said plane; and carrying out a centring operation adapted to align, in said plane, the axis of rotation (R) of the tyre (2) with the axis of rotation (Z) of the rotating table (35). The centring operation comprises the identification, in said plane, of the axis of rotation (R) of the tyre (2) by: a) acquisition of an image of the tyre (2) laid on said supporting portion (36) of the rotating table (35); b) definition, in the acquired image, of a number n of analysis directions α1, α2, intersecting at one selected central point (Pc), with n and i integers, n>1 and 1 ≤ i ≤ n; c) for each analysis direction αi' definition, in the acquired image, of a number m of potential axes of symmetry Si1, Si2,.. sij, Sim, perpendicular to the analysis direction a\, where m and j are integers, with m>1 and 1 ≤ j ≤ m; calculation of a level of symmetry of the image with respect to each of said potential axes of symmetry Si1, Si2,.. Sij,.. Sim, wherein said level of symmetry is indicative of the probability that the centre of the tyre (2) is on the respective potential axis of symmetry Si1, Si2, Sij, Sim; determination of a probability distribution Pal indicative of a variation of said level of symmetry along said analysis direction a,; d) determination of a centre of the tyre (2) on the basis of a cumulative probability distribution Pmerged obtained through a combination of the probability distributions Pxi calculated for said analysis directions α1, α2,.. αi,...αn) identification of the axis of rotation (R) of the tyre (2) in an axis that passes through said determined centre and perpendicular to said plane.