What is Poka-Yoke?
A poka-yoke device is any mechanism that either prevents a mistake from being made or makes the mistake obvious at a glance.
As Shingo writes, “The causes of defects lie in worker errors, and defects are the results of neglecting those errors. It follows that mistakes will not turn into defects if worker errors are discovered and eliminated beforehand„ [Shingo 1986, p.50].