Machine Vision News
Vol. 4, 1999
Looking Beyond Irregularities-
Machine Vision Technology to Inspect Carpets
"Carpet inspection by
PROSPECT machine vision at Foamtex A/S, Denmark."
PROSPECT has been developed
to inspect carpets as they come off the production line. The machine vision
system is able to identify defects in carpets more effectively and more
cheaply than ever before. Using PROSPECT, fewer faults go undetected and
less waste is produced, generating both environmental and economic benefits.
PROSPECT was developed by
Kjaergaard Industri Automatik A/S, experts in machine vision and quality
control, in collaboration with the High Performance Computing and Networking
(HPCN) experts EPCC and the carpet manufacturers Foamtex. The development
project was funded by the European Commission, and runs from 1 August 1998
to 31 March 1999. It is presently in its test phase.
Kjaergaard gained experience
with PROSPECT by first using the technology to inspect colour print on
cans using line-scan cameras. However, the challenge was to enhance the
technology to cope with the many irregularities that are present in weaving
The key to the PROSPECT system
is the use of powerful but inexpensive computing technology to analyse
the image of the carpet. The system must be able to process the images
quickly in order to keep up with the speed of the carpet as it comes off
the production line. The system tackles this challenge using state-of-the-art
Digital Signal Processor (DSP) technology and vision systems.
The ability to use artificial
vision and image processing techniques to detect such minute faults across
an entire product has only recently become available. The computing power
required is significant and until now has been very expensive. Not anymore:
EPCC is running the ENTICE project as part of a network of technology transfer
nodes (TTN) established by the European Commission to help companies, and
in particular small and medium sized enterprises, to exploit High Performance
Computing and Networking (HPCN) technology.
||Left: The system can also
detect different colour errors.
Right: A thread bursting
will show in the picture and result in an error message from the system.
In carpet manufacture, faults
can occur with colour, pattern, or pile; or faults can be introduced by
the carpet backing process. A prototype of the PROSPECT system has been
implemented and tested in the Foamtex factory. The most expensive faults
from the manufacturerÕs point of view were chosen from a range of
over 20 possible faults in carpet production. The system was set to detect
the four faults most frequently reported as customer complaints. These
faults include tiny areas - from 2 x 6 millimetres - where some
of the carpet pile is missing or where there has been an unsuccessful repair
of missing pile. Such faults are difficult to see with the human eye but
their detection is vital for customer satisfaction.
Work carried out by EPCC
has shown that HPCN technology can be used, for example, to expand the
system to accommodate wider carpets, faster production, and to detect different
types of faults. This ability to ÒscaleÓ the system to cope
with the workload makes it versatile and easy to upgrade. Detection rates
of over 95% have been achieved when using this type of technology to detect
faults in other manufacturing processes, and the partners hope that the
carpet industry will soon be able to see the same benefit.
- el & industri automatik a/s