
Poka-yoke - vitoc
https://en.wikipedia.org/wiki/Poka-yoke
======
philwelch
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.

~~~
cc439
The way in which the term is used in the manufacturing industry is a different
from "foolproofing" in practice. Generally, a Poka-Yoke is a step added to a
process that requires an operator to stop and think about what is going on and
whether everything is within spec before proceeding with the next step.

One example I can think of would be a torque tool used in a critical step of
the assembly process. Since modern factories allow different models of roughly
similar product types to be assembled on the same production line, it is
important that the torque tool is run using the correct settings for each
model. In this example, the operator has to scan a barcode on the vehicle and
the corresponding barcode on the computerized torque tool before the tool will
work. This not only sets the tool to the correct setting, it forces the
operator to stop and think for a second when the tool doesn't work. By doing
this as the first step, it also ingrains the knowledge of which model number
the operator is working on as they consciously have to scan the right barcode
on the tool as there's a unique barcode for each variant they'll see coming
down the line. That way they are more likely to catch any incorrect/mismatched
parts tied to later stages of assembly carried out at their station (i.e. they
know they are working on Model X Sport but the parts bin shadowing this
chassis has a cosmetic piece that is only for the Model X Limited).

Also, I;ve always found it funny that the phrase sounds like poke-a-yoke
(yoke, as in yokel) given how it's used in the industry to describe a way of
prodding someone to pay attention.

~~~
csours
People will generally operate with common sense until incentives or pressure
is applied.

If you are under extreme pressure to produce a certain count of parts, common
sense is suspended and people do things like ship problems on down the line.
(See also local optimization)

~~~
FooHentai
You have to account for fatigue also. While a repeated process can drop into
the 'automatic' mode where you're unfocused but still running through the
task, critical validations can be omitted when focus is not retained. These
techniques guard effectively against that, as there are clear, focus-inducing
markers when something is wrong in the process.

This is the main thing you're guarding against. It's not complacency, or
additional pressures... It's just plain old boring fatigue which on a long
enough time span will hit every operator.

------
jihadjihad
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
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
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.

------
mglhn
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
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.

------
camtarn
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
Meanwhile in Australia, Tram drivers just read the newspaper while driving:
[https://www.instagram.com/p/Bn-DGXYjNOl/?taken-
by=browncardi...](https://www.instagram.com/p/Bn-DGXYjNOl/?taken-
by=browncardigan)

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

------
2dollars27cents
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.

------
gorb314
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.

------
sharno
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

------
MrEfficiency
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.

~~~
jaggederest
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
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
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.

------
ninjakeyboard
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
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_\(manufacturing\))

------
baxtr
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

------
User23
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.

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fouc
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.

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

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

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

