Abstract :
Poka-yoke is a quality assurance
technique developed by Japanese manufacturing engineer Shigeo Shingo. The aim of poka-yoke is to eliminate
defects in a product by preventing or correcting mistakes as early as possible.
Poka-yoke has been used most frequently in manufacturing environments.
Hewlett Packard currently develops its
Common Desktop Environment software to run in twelve locales or languages.
Traditional testing of this localized software is technically difficult and
time-consuming. By introducing
poka-yoke (mistake-proofing) into our software process, we have been able to prevent literally hundreds of
software localization defects from reaching our customers.
This paper describes the poka-yoke
quality approach in general, as well as our particular use of the technique in
our localization efforts. Poka-yoke is providing a simple, robust and painless
way for us to detect defects early in our localization efforts.
What is Poka-yoke?
Poka-yoke is a Japanese term that means
"mistake-proofing". A poka-yoke is any mechanism in a lean
manufacturing process that helps an equipment operator avoid (yokeru) mistakes (poka).
Its purpose is to eliminate product
defects by preventing, correcting, or drawing attention to human errors as they
occur.[1] The concept was formalised, and the term adopted, by Shigeo Shingo as part
of the Toyota Production System. It was originally described as baka-yoke, but as this means
"fool-proofing" (or "idiot-proofing") the name was changed
to the milder poka-yoke.
Categories of poka-yoke devices
Poka-yoke devices fall into two major
categories: prevention and detection.
A prevention device engineers the process so that it is impossible to make
a mistake at all. A classic example of a prevention device is the design of a 3.5 inch computer
diskette.The diskette is carefully engineered to be slightly asymmetrical so
that it will not fit into the disk drive in any orientation other than the
correct one. Prevention devices remove the need to correct a mistake, since the
user cannot make the mistake in the first place.
A detection device signals the user when a mistake has been made, so that
the user can quickly correct the problem. The small dish used at the Yamada
Electric plant was a detection device; it alerted the worker when a spring had been
forgotten. Detection devices typically warn the user of a problem, but they do
not enforce the correction.
We are surrounded every day by both
detection and prevention poka-yoke devices, though we may not usually think of
them as such. My microwave will not work if the door is open (a prevention
device). My car beeps if I leave the key in the ignition (a detection device).
At few years ago, some cars were designed not to start until the passengers had
buckled their seat belts (a prevention device); but this mechanism was too intrusive and
was replaced by a warning beep (a detection device).
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