on-line non-contact system for grinding wheel wear measurement

An on-line non-contact method for measuring the wear of a
form grinding wheel is presented. A CCD (charge coupled
device) camera with a selected optical lens and a frame
grabber was used to capture the image of a grinding wheel.
The analogue signals of the image were transformed into
corresponding digital grey level values. Using the binarisation
technique, the images of background and the grinding wheel
were segmented. Thus the grinding wheel edge was identified.
The ‘mapping function method’ is used to transform an image
pixel coordinate to a space coordinate. An auto-focus technology
is also developed. The statistics of pixels are used as
the focusing index. The signal was sent through an 8255
control card to drive a d.c. motor, and then to control the
lens focusing movement to acquire the focal plane. The images
before and after the grinding process were captured. The
position deviation of the grinding wheel edge was analysed.
Then, the grinding wheel wear was evaluated. The wear detection
accuracy is about 1m