Counterfeit coin detection device prototype

A group of researchers in the Department of Computer Science and Industrial Engineering, University of Lleida, Spain have tried to make a sensor that can detect a counterfeit euro coin. An optical mouse sensor compares images of a questionable coin with reference images from a genuine coin using a unique algorithm. Suspected counterfeit money is scanned, compared, and then identified.

For now, the money being analyzed is a coin, the two Euro (€2) the most valuable and most often counterfeited coin in the European Union. In 2007, fake or counterfeit replicas were prolific. There were 211,100 removed from circulation, making a total value of EUR 422,200 or 631,442 US Dollars. There are eight denominations of the Euro - 1, 2, 5, 10, 20 and 50 cent, €1 and €2.

Photo: Counterfeit coin detection device prototype

Low cost sensors in vending machines measure some physical characteristics of coins such as weight, size, thickness, conductivity, and magnetic or acoustic properties. When these physical properties are very similar, image-based coin recognition can be used. The system must detect coins from non EU countries that are similar in size and weight to the two-Euro coin.

Photo: ADNS-3088 optical mouse sensor

The new vision-based measurement system was explained in a paper published by Marcel Tresanchez, Tomàs Pallejà, Mercè Teixidó and Jordi Palacín. The device consists of a dedicated microprocessor, combined with an optical mouse sensor, including a digital signal processor, a CMOS camera, and a lateral infrared light source that illuminates the coin’s surface casting shadows which help detect small variations in the roughness of the surface. A convex lens captures the reflected light. The mouse sensor compares images at over 6,400 frames per second. The acquired image is only 1/14 of the front side of the two Euro coin. Tresanchez says images must be captured in real time, with a minimum resolution of 15x15 pixels, and preferably an LED- or infrared-based sensor, instead of laser technology. The research team used the ADNS-3088 optical mouse sensor from Avago Technologies.

Source: brightsideofnews.com