Oil Stain detection

I have been asked by a client who runs a towel business, the type you find in some public WC to dry your hands , if there is a way to sense oil stains on the towel. He has a custom made washing macine. He puts the roll with the towel on a cylinder and he passes it with the aid of some rollers through a solution then from a hot chamber where they become dry and finally the towel is reeled and ready for use.He wants a sensor to detect if the washed towel has any stains on it, usually oil stains and sound an alarm. The towel is not single colored it usualy has three stripes of different colors.
Any ideas will be appreciated!

A colour sensor perhaps

http://www.sick.de/de/products/categories/industrial/coloursensors/en.html

Youd need quite a few depending how wide the towell is, i havent seen/heard of any that are wide (like a curtain) which would be better for you.

Maybe someone else here has some ideas.

The first thing that comes to my mind is a vision system.
Depending on the configuration for inspection, you could use either a line or area scan camera.
What size are the towels and the speed of the towels as they are being rewound?

Heres a link for machine vision. Give them a call or shoot them an email. They could likely help you out.

http://www.dvtsensors.com/

Unless something has changed since Congnex bought out DVT, then they won't be of much help. In all the times I've looked at vision applications, everytime I've called DVT for help, their answer is to call an integrator familiar with the DVT systems for help. I have NEVER got technical assistance from DVT in the front end. Contrast that to Cognex, Banner, and Keyence. Each one of those was given an application and a sample of what was needed and in 2 weeks, I had reports and sugested equipment from each one of those (even one who said they could not do it). I guess my point is to consider other companies for vision. DVT lost out on a lot because they wouldn't do a little front end work for my application.

Thank's , I have sent emails to both sick and dvt. Let's hope they answer.

I was told that DVT wants you to go thought the local ASP [Associate Service Provider?] first since that is what they are there for.
With that said, I have had great support from both the ASP and DVT, so may be I have been lucky since I have great local support if I need it but just the opposite from some of the other companies.



GEOFRA,

If you could take pictures in bmp format of the towels with oil stains and some of the towels without an oil stain, I would be happy to look at them under the emulator if you like.