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Poka-yoke

by vitoc on 9/23/18, 9:03 AM with 60 comments

• by philwelch on 9/24/18, 12:15 PM

  This seems like an interesting and useful process design concept on one hand, and on the other hand, it also sounds like a Japanese buzzword for foolproofing (in fact, the article notes that the term was originally “baka-yoke”, which is literally “foolproof” or “idiot-proof”). On the one hand, I don’t think Toyota invented the concept of foolproofing; on the other hand, giving it a cool buzzword gives you an excuse to talk about it, which means you’re more likely to actually do it when appropriate.

  I’m also kind of amused at how the entire business world basically said, “man, this company made super reliable cars in the 80’s and 90’s[1], let’s learn their secrets” and it turns out that once you strip away the exotic Japanese veneer, it’s mostly just systemized common sense. Which is not a minor thing to do, to be fair, except it’s easy for businesses to take good, well-systemized ideas and utterly misapply them.

  [1] As far as I know, they still make reliable cars. But you can still drive a 92 Camry today if you wanted to with little fuss. By definition, we’re 26 years away from seeing if today’s Camry is quite that reliable.

• by jihadjihad on 9/24/18, 12:13 PM

  One of my favorite examples of poka-yoke is the Apple MagSafe charger. The magnetic part itself is foolproof, sure. But the genius part is the small metal knob that meshes with the removable AC prong piece. It is impossible to insert that piece in any other way than it was intended, and the solution is unobtrusive, clean, and simple.

• by mglhn on 9/24/18, 2:52 PM

  Just want to share some stories:

  One of my professors (I am an Industrial engineer) used the example of a SIM card. I imagine people can still get it wrong when putting it in, but much less so (ehem USB) because of that slight cut in the rectangle. It also helps a lot when manufacturing those things to get the orientation right.

  Another mistake proofing anecdote I've heard was about one of his students interning at a company that packages soap. Somehow there were empty boxes going through the conveyors after some process change. Some of the mechanical engineers were already thinking about some modification to the conveyors that detect weight, etc. The IE student apparently simply went in one of the back offices and got a spare electric fan and pointed it at the conveyor so the empty boxes fly out. Troubleshooting doesn't have to be expensive.

• by camtarn on 9/24/18, 1:01 PM

  In a similar vein, and also from Japan - 'pointing and calling', used on the railways.

  https://en.wikipedia.org/wiki/Pointing_and_calling

• by synodinos on 9/24/18, 1:24 PM

  This is a very useful concept even beyond physical design. When I evaluate UIs the top 5 things I look into are:

  Visual rhyme, Accessibility, Affordances, Mistake-proofing (“Poka-yoke”), and Defensive design.

  https://medium.com/@dio/5-things-to-consider-when-evaluating...

• by 2dollars27cents on 9/24/18, 5:24 PM

  Take a look at this Audi production video and you start to notice poka-yoke being used when there is a human in the loop. https://www.youtube.com/watch?v=nZkyfZqlptA

  In my experience these things are developed over time in response to failure. Always keeping the poka-yoke concept in the back of your mind helps when designing systems, but you don't really know how people will misuse tools until they're in action.

• by gorb314 on 9/24/18, 4:58 PM

  From my understanding, poka-yoke addresses the problem where "[...] the mistakes are allowed to reach the customer".

  In software, we know that the later a bug is caught, the more expensive (in terms of time / resources) it is to fix. So we want to catch bugs / mistakes earlier.

  The "simple" idea that Poka-yoke introduces is to make it harder to make the mistake in the first place. If a physical component can be mounted more than one way, but there is only one correct way, then design it such that it is impossible to mount it incorrectly. This can be done by making the mounting holes for the part asymmetrical, for example.

  IMO, in software a similar concept would be to fail early and fail hard.

• by sharno on 9/24/18, 12:48 PM

  I guess that aligns with type systems in programming languages. The type systems make sure that the plain simple mistake of passing an integer in the place of a string is prevented. Of course more powerful type systems like Haskell fool proof it more if the developer is putting the effort of writing more types to restrict things more.

  I think that's a clear implementation of poka-yoke on the programming languages level allowing developers to fool proof their APIs

• by MrEfficiency on 9/24/18, 12:41 PM

  I wrote about putting a line on your shower handle to denote 'good temp'. (used a shower crayon, or anything)

  Now I put my handle in the correct location and its warm everyday.

• by ninjakeyboard on 9/24/18, 5:40 PM

  The term is used quite often in manufacturing. For a part when picking, for example, a part may have two colored squares on the label so the operator looks at the color on the squares to validate as an extra step. We call the colored squares the poka-yoke.

• by tsuresh on 9/24/18, 6:35 PM

  With a similar intention, Toyota also came up with the Andon cord - https://en.wikipedia.org/wiki/Andon_(manufacturing)

• by baxtr on 9/24/18, 12:55 PM

  This concept is very useful, not only in manufacturing but also at home. As somebody else has explained, MegSafe used this principle. Another great example is our dryer at home: the filter that needs to be cleaned every month or so has to be plugged back in in a certain way. They perforated they filter such that there’s absolutely no way to plug in back in the wrong way. Another great application would be gas vs diesel knobs at gas stations. I’m not sure whether new cars/pump provide that already

• by User23 on 9/24/18, 7:13 PM

  I'd never heard of this, but it's an excellent concept that I try to apply to my daily living.

  For example I accident-proof myself against spills by keeping a beverage in a place where it's unlikely to be knocked over, but if it is that the consequences are easy to deal with rather than soaking a keyboard or something. In physical terms it mostly boils down to minimizing the potential energy of everyday objects.

• by fouc on 9/24/18, 12:11 PM

  I think this aligns with the notion of an Exocortex, extending our brain and our IQ by making it easier to do the correct thing.

• by csense on 9/24/18, 8:11 PM

  Whenever you invent better idiot-proofing, someone else will invent a better idiot.

• by manceraio on 9/25/18, 2:31 PM

  A poka-yoke in real life is like those games for kids where they have to place squares with squares and triangles with triangles.

• by avodonosov on 9/24/18, 8:35 PM

  Does this qualify as "news" for HN? That's just a wikipedia article.