8 ms·

Poka-yoke

160 points by vitoc 8y ago

fouc 8y ago
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.
jihadjihad 8y ago
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.
- codetrotter 8y ago
  I still don’t get why they removed it. MagSafe was a great thing. Sure some people got things stuck in the connector but that is a much smaller problem than having your laptop pulled along with the cable when someone trips on your charger.
  - samatman 8y ago
    Anecdotally, I just accidentally kicked my USB-C charger loose, from the charger side. Pretty sure that would have stressed the old MagSafe cables. I expect to have to replace the cable at some point, but not the charging brick or the ports. For those with large dogs, toddlers, or just klutziness (I'm borderline), magnetic breakaway cables are available.
- dfox 8y ago
  The metal knob actually is PE pin for the AC plug, which is used in some parts of the world with presumably stricter low voltage safety standards which would not allow for the chassis of macbook to float at what is essentially half of the mains voltage (this is why you get slight tingling sensation if you run back of your hand over macbook that is plugged into charger with two-prong plug).
philwelch 8y ago
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.
- sooheon 8y ago
  > giving it a cool buzzword They called it the obvious word in their own language, it's only a cool buzzword to non-native speakers reading English Wikipedia. > systemized common sense Of course. And still businesses are full of systemic problems, where common sense fails. Just like well written programs are just "systemized instructions", but most programs are buggy and brittle. Clarity in defining and executing on simple concepts is worth a lot.
  - wlesieutre 8y ago
    >They called it the obvious word in their own language, it's only a cool buzzword to non-native speakers reading English Wikipedia. Same place "Kanban" came from
  - philwelch 8y ago
    > They called it the obvious word in their own language, it's only a cool buzzword to non-native speakers reading English Wikipedia. I'm more making fun of the American business consultants who are going to try and cargo-cult this idea and make it sound more impressive than it actually is by not using the already commonplace American English idiom that describes the same concept. The term "poka-yoke" seems to date from the 1960's, while "foolproof" is well-attested before WWII, which makes me recklessly speculate that the term is likely a translation from the English in the first place. Since Japan sought out and received a lot of guidance and advice from Americans about rebuilding their manufacturing industry (which is logical, given the fact that we more or less won the war by out-manufacturing them), I wouldn't be surprised if someone casually used the word "foolproof", and merely translating the idiom introduced the underlying concept. (Kind of like how we stole "earworm" and "punchable face" from German idioms). And hey, maybe the extra step of introducing a new foreign idiom, or even reintroducing an idiom that we already have, is valuable because it puts a bright flashing light on it. Buzzwords only become buzzwords because there's a substance behind them, it's just when the bright flashing light outshines the substance that it becomes a problem. > Clarity in defining and executing on simple concepts is worth a lot. See, that's the thing, it's execution. You can talk about foolproofing your processes and your tools, and half the time you end up getting in people's way as often as you prevent any actual errors, because no matter how well you foolproof something, there's always some fool out there who's even smarter than you are when it comes to discovering new and creative ways to screw things up. But the other half of the time, not doing it is going to just completely burn you. The judgment of differentiating those two cases from each other is the valuable part, not just the concept of error-proofing (or poka-yoke) in the first place.
MrEfficiency 8y ago
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.
- gattilorenz 8y ago
  Yep, that's a good tip. Read this, if you haven't: https://en.wikipedia.org/wiki/The_Design_of_Everyday_Things https://en.wikipedia.org/wiki/The_Design_of_Everyday_Things It's a book about how minor design differences can basically change your life. It will make your life miserable, because you will start noticing all the stupidly bad design decision and blame the designer in most cases.
- jaggederest 8y ago
  This only works if you have a thermostatic mixer or consistent temperature of your hot water. The gold standard is a pressure-balanced thermostatic mixer, which always outputs the same temperature at the same setting. Most of them come with two knobs, "temperature" and "flow". I miss the one I had a while ago.
  - projektfu 8y ago
    I don't have a fancy mixer, but if your hot water heater is reasonably consistent and you have a working main pressure regulating valve, you should have enough consistency for this to work.
    - jaggederest 8y ago
      It's funny because you'd think that'd be the case, but in practice the difference is night and day. Thermostatic mixers will often have a temperature dial on the output, and it'll be within ~2 degrees of that temperature as soon as the hot water available exceeds that temperature.
  - pdpi 8y ago
    Even without a thermostatic mixer, “good temp” is unlikely to be freezing cold or scalding hot. It’s a good enough first approximation that you can correct after you jump in
sharno 8y ago
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
baxtr 8y ago
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
camtarn 8y ago
In a similar vein, and also from Japan - 'pointing and calling', used on the railways. https://en.wikipedia.org/wiki/Pointing_and_calling https://en.wikipedia.org/wiki/Pointing_and_calling
- toomanybeersies 8y ago
  Meanwhile in Australia, Tram drivers just read the newspaper while driving: https://www.instagram.com/p/Bn-DGXYjNOl/?taken-by=browncardigan https://www.instagram.com/p/Bn-DGXYjNOl/?taken-by=browncardi...
synodinos 8y ago
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-ui-ux-7d57a40e4e6d https://medium.com/@dio/5-things-to-consider-when-evaluating...
mglhn 8y ago
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.
- teddyh 8y ago
  That’s a story which I have seen a few variants of before this; I doubt this is really one of the professor’s students, it’s more likely an urban legend.
gorb314 8y ago
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.
2dollars27cents 8y ago
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 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.
ninjakeyboard 8y ago
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.
tsuresh 8y ago
With a similar intention, Toyota also came up with the Andon cord - https://en.wikipedia.org/wiki/Andon_(manufacturing) https://en.wikipedia.org/wiki/Andon_(manufacturing)
User23 8y ago
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.
csense 8y ago
Whenever you invent better idiot-proofing, someone else will invent a better idiot.
avodonosov 8y ago
Does this qualify as "news" for HN? That's just a wikipedia article.
manceraio 8y ago
A poka-yoke in real life is like those games for kids where they have to place squares with squares and triangles with triangles.

160 points by vitoc 8y ago

fouc 8y ago

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.

jihadjihad 8y ago

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.

codetrotter 8y ago
I still don’t get why they removed it. MagSafe was a great thing. Sure some people got things stuck in the connector but that is a much smaller problem than having your laptop pulled along with the cable when someone trips on your charger.
- samatman 8y ago
  Anecdotally, I just accidentally kicked my USB-C charger loose, from the charger side. Pretty sure that would have stressed the old MagSafe cables. I expect to have to replace the cable at some point, but not the charging brick or the ports. For those with large dogs, toddlers, or just klutziness (I'm borderline), magnetic breakaway cables are available.
dfox 8y ago
The metal knob actually is PE pin for the AC plug, which is used in some parts of the world with presumably stricter low voltage safety standards which would not allow for the chassis of macbook to float at what is essentially half of the mains voltage (this is why you get slight tingling sensation if you run back of your hand over macbook that is plugged into charger with two-prong plug).

philwelch 8y ago

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.

sooheon 8y ago
> giving it a cool buzzword They called it the obvious word in their own language, it's only a cool buzzword to non-native speakers reading English Wikipedia. > systemized common sense Of course. And still businesses are full of systemic problems, where common sense fails. Just like well written programs are just "systemized instructions", but most programs are buggy and brittle. Clarity in defining and executing on simple concepts is worth a lot.
- wlesieutre 8y ago
  >They called it the obvious word in their own language, it's only a cool buzzword to non-native speakers reading English Wikipedia. Same place "Kanban" came from
- philwelch 8y ago
  > They called it the obvious word in their own language, it's only a cool buzzword to non-native speakers reading English Wikipedia. I'm more making fun of the American business consultants who are going to try and cargo-cult this idea and make it sound more impressive than it actually is by not using the already commonplace American English idiom that describes the same concept. The term "poka-yoke" seems to date from the 1960's, while "foolproof" is well-attested before WWII, which makes me recklessly speculate that the term is likely a translation from the English in the first place. Since Japan sought out and received a lot of guidance and advice from Americans about rebuilding their manufacturing industry (which is logical, given the fact that we more or less won the war by out-manufacturing them), I wouldn't be surprised if someone casually used the word "foolproof", and merely translating the idiom introduced the underlying concept. (Kind of like how we stole "earworm" and "punchable face" from German idioms). And hey, maybe the extra step of introducing a new foreign idiom, or even reintroducing an idiom that we already have, is valuable because it puts a bright flashing light on it. Buzzwords only become buzzwords because there's a substance behind them, it's just when the bright flashing light outshines the substance that it becomes a problem. > Clarity in defining and executing on simple concepts is worth a lot. See, that's the thing, it's execution. You can talk about foolproofing your processes and your tools, and half the time you end up getting in people's way as often as you prevent any actual errors, because no matter how well you foolproof something, there's always some fool out there who's even smarter than you are when it comes to discovering new and creative ways to screw things up. But the other half of the time, not doing it is going to just completely burn you. The judgment of differentiating those two cases from each other is the valuable part, not just the concept of error-proofing (or poka-yoke) in the first place.

MrEfficiency 8y ago

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.

gattilorenz 8y ago
Yep, that's a good tip. Read this, if you haven't: https://en.wikipedia.org/wiki/The_Design_of_Everyday_Things https://en.wikipedia.org/wiki/The_Design_of_Everyday_Things It's a book about how minor design differences can basically change your life. It will make your life miserable, because you will start noticing all the stupidly bad design decision and blame the designer in most cases.
jaggederest 8y ago
This only works if you have a thermostatic mixer or consistent temperature of your hot water. The gold standard is a pressure-balanced thermostatic mixer, which always outputs the same temperature at the same setting. Most of them come with two knobs, "temperature" and "flow". I miss the one I had a while ago.
- projektfu 8y ago
  I don't have a fancy mixer, but if your hot water heater is reasonably consistent and you have a working main pressure regulating valve, you should have enough consistency for this to work.
  - jaggederest 8y ago
    It's funny because you'd think that'd be the case, but in practice the difference is night and day. Thermostatic mixers will often have a temperature dial on the output, and it'll be within ~2 degrees of that temperature as soon as the hot water available exceeds that temperature.
- pdpi 8y ago
  Even without a thermostatic mixer, “good temp” is unlikely to be freezing cold or scalding hot. It’s a good enough first approximation that you can correct after you jump in

sharno 8y ago

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

baxtr 8y ago

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

camtarn 8y ago

In a similar vein, and also from Japan - 'pointing and calling', used on the railways. https://en.wikipedia.org/wiki/Pointing_and_calling https://en.wikipedia.org/wiki/Pointing_and_calling

toomanybeersies 8y ago
Meanwhile in Australia, Tram drivers just read the newspaper while driving: https://www.instagram.com/p/Bn-DGXYjNOl/?taken-by=browncardigan https://www.instagram.com/p/Bn-DGXYjNOl/?taken-by=browncardi...

synodinos 8y ago

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-ui-ux-7d57a40e4e6d https://medium.com/@dio/5-things-to-consider-when-evaluating...

mglhn 8y ago

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.

teddyh 8y ago
That’s a story which I have seen a few variants of before this; I doubt this is really one of the professor’s students, it’s more likely an urban legend.

gorb314 8y ago

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.

2dollars27cents 8y ago

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 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.

ninjakeyboard 8y ago

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.

tsuresh 8y ago

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

User23 8y ago

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.

csense 8y ago

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

avodonosov 8y ago

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

manceraio 8y ago

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