Tire appearance inspection apparatus and method

Patent metadata

Field	Value
Publication number	US-9677879-B2
Application number	US-201113114698-A
Country	US
Kind code	B2
Filing date	May 24, 2011
Priority date	May 24, 2010
Publication date	Jun 13, 2017
Grant date	Jun 13, 2017

Abstract

A tire appearance inspection apparatus and method employing image processing is capable of performing tire appearance inspection with great accuracy. The tire appearance inspection apparatus includes a sectional shape acquiring device for acquiring cross-sectional shapes of a tire in the radial direction along the circumference of the tire, an arc fitting device for fitting an arc to each of the cross-sectional shapes, an arc center position calculating device for calculating the center positions of the arcs, and a sectional shape aligning device for aligning the cross-sectional shapes using the center positions of the arcs for the cross-sectional shapes.

First claim

What is claimed is:

1. An image processing apparatus for tire appearance inspection comprising:
a table that is configured to hold a tire to be inspected;
a plurality of cameras positioned within an inner opening area of the tire and configured to capture images of an inside surface of a sidewall of the tire; and
a processor configured to:
control the plurality of cameras to acquire images such that each of the images includes a cross-sectional shape of the inside surface of the sidewall of the tire in a tire radial direction along a circumference of the tire, the inside surface of the tire sidewall including a bead, wherein the plurality of cameras are controlled such that, for each of the cross-sectional shapes, data from the acquired images includes the following information, which is then extracted:
a bead-side extremal value and a sidewall-side extremal value;
a bead-side arc point selected from positions 20 to 80 pixels on a curve leftward from the bead-side extremal value and another bead-side arc point selected from positions 20 to 80 pixels on a curve rightward from the bead-side extremal value; and
a sidewall-side arc point selected from the positions 20 to 80 pixels on a curve leftward from the sidewall-side extremal value and another sidewall-side arc point selected from the positions 20 to 80 pixels on a curve rightward from the sidewall-side extremal value;

for each of the acquired images:
set a bead-side arc by calculating the bead-side arc point, the other bead-side arc point and the bead-side extremal value;
set a sidewall-side arc by calculating the sidewall-side arc point, the other sidewall-side arc point and the sidewall-side extremal value;
determine a center position of the bead-side arc, the center position of the bead-side arc being an intersection of a normal line from a midpoint of a line segment connecting the bead-side arc point and the bead-side extremal value and a normal line from a midpoint of the line segment connecting the bead-side extremal value and the other bead-side arc point; and
determine a center position of the sidewall-side arc, the center position of the sidewall-side arc being an intersection of a normal line from a midpoint of a line segment connecting the sidewall-side arc point and the sidewall-side extremal value and a normal line from a midpoint of the line segment connecting the sidewall-side extremal value and the sidewall-side arc point;

calculate a bead-side center curve by performing a Fourier transform on a line connecting the center positions of the bead-side arcs of the cross-sectional shapes in the acquired images;
calculate a sidewall-side center curve by performing a Fourier transform on a line connecting the center positions of the sidewall-side arcs of the cross-sectional shapes in the acquired images; and
generate an enhanced inspection image by aligning each of the acquired images by placing the center positions of the bead-side arcs for the cross-sectional shapes on the bead-side curve and placing the center positions of the sidewall-side arcs on the sidewall-side curve.

2. The image processing apparatus for tire appearance inspection according to claim 1 , wherein, in the Fourier transform, a primary component is employed only.

3. The image processing apparatus for tire appearance inspection according to claim 1 , wherein the bead-side extremal value is a point where a straight line connecting the inflection point of the cross-sectional shape of the image and the bead-side end point thereof, when parallely moved, touches an upward swelling curve near the bead of the cross-sectional shape.

4. The image processing apparatus for tire appearance inspection according to claim 3 , wherein a position where the upward-swelling curve is connected to a downward-swelling curve along the sidewall is the inflection point on the respective cross-sectional shape.

5. The image processing apparatus for tire appearance inspection according to claim 4 , the sidewall-side extremal value is the position where a straight line parallel to the coordinate axis in the radial direction, when moved up or down, touches the downward-swelling curve along the sidewall.

6. The image processing apparatus for tire appearance inspection according to claim 1 , wherein the processor is further programmed to:
automatically detect whether or not the tire has any defective spots based on the enhanced inspection image; and
determine that the tire should be rejected, if defective spots are detected in the enhanced inspection image.

7. An image processing method for tire appearance inspection comprising:
controlling a plurality of cameras that are: (i) positioned within an inner opening area of a tire to be inspected that is held by a table, and (ii) configured to capture images of an inside surface of a sidewall of the tire, wherein the plurality of cameras are controlled to acquire images such that each of the images includes a cross-sectional shape of the inside surface of the sidewall of the tire in tire radial direction along a circumference of the tire, the inside surface of the tire sidewall including a bead, and the plurality of cameras are controlled such that, for each of the cross-sectional shapes, data from the acquired images includes the following information, which is then extracted:
a bead-side extremal value and a sidewall-side extremal value;
a bead-side arc point selected from positions 20 to 80 pixels on a curve leftward from the bead-side extremal value and another bead-side arc point selected from positions 20 to 80 pixels on a curve rightward from the bead-side extremal value; and
a sidewall-side arc point selected from positions 20 to 80 pixels on a curve leftward from the sidewall-side extremal value and another sidewall-side arc point selected from positions 20 to 80 pixels on a curve rightward from the sidewall-side extremal value;

for each of the acquired images:
setting a bead-side arc by calculating the bead-side arc point, the other bead-side arc point and the bead-side extremal value;
setting a sidewall-side arc by calculating the sidewall-side arc point, the other sidewall-side arc point and the sidewall-side extremal value;
determining a center position of the bead-side arc, the center position of the bead-side arc being an intersection of a normal line from a midpoint of a line segment connecting the bead-side arc point and the bead-side extremal value and a normal line from a midpoint of the line segment connecting the bead-side extremal value and the other bead-side arc point; and
determining a center position of the sidewall-side arc, the center position of the sidewall-side arc being an intersection of a normal line from a midpoint of a line segment connecting the sidewall-side arc point and the sidewall-side extremal value and a normal line from a midpoint of the line segment connecting the sidewall-side extremal value and the sidewall-side arc point;

calculating a bead-side center curve by performing a Fourier transform on a line connecting the center positions of the bead-side arcs of the cross-sectional shapes in the acquired images;
calculating a sidewall-side center curve by performing a Fourier transform on a line connecting the center positions of the sidewall-side arcs of the cross-sectional shapes in the acquired images; and
generating an enhanced inspection image by aligning each of the acquired images by placing the center positions of the bead-side arcs for the cross-sectional shapes on the bead-side curve and placing the center positions of the sidewall-side arcs on the sidewall-side curve.

8. The image processing method apparatus for tire appearance inspection according to claim 7 , wherein, in the Fourier transform, a primary component is employed

Assignees

• Mizutani Akinobu
• Kaneko Tomoyuki
• Bridgestone Corp

Inventors

• Mizutani Akinobu
• Kaneko Tomoyuki

Classifications

• G01M17/027

  using light, e.g. infrared, ultraviolet or holographic techniques · CPC title

• G01B11/2522 Primary

  the position of the object changing and being recorded · CPC title

• G06T2207/30108

  Industrial image inspection · CPC title

• G06T7/344

  involving models · CPC title

• G01N21/954

  Inspecting the inner surface of hollow bodies, e.g. bores · CPC title