Hacker News Reader

Comment by landgenoot | Hacker News Reader

By reading the title, I assumed this article would be about the remaining time indication, which is a lie on some washing machines.

View on HN

Some washing machines actually measure how dirty the drain water is to decide whether to do another pass with fresh water. Since this is a dynamic decision, the remaining time cannot be accurately predicted in advance.

(Not saying this is true for all, some might just lie outright).

The expensive ones do. The cheap ones or lower models of the expensive ones fake it to look more expensive. Sensors cost money.

Cheap washing machines are able to weigh the load and adjust the progam accordingly.

A big factor of uncertainty at the end of the cycle is the weight distribution for spinning.

Newer washing machines rotate the drum slowly until the clothes separate, bringing the centre of mass closer to the axis of rotation, leading to much less vibration during the spin cycle. If the weight does not distribute after n cycles (e.g. if you put a single large and heavy duvet cover inside), some lower the spin RPM to a level that is deemed acceptable.

I've always assumed that they perform this measurement via the current curve of the motor during a rotation. Flattened curve -> distributed load, CG close to spin axis. Huge spike -> offset load, CG far away from spin axis -> bang bang bang walking washing machine.

https://www.youtube.com/watch?v=3mqy5uWXvzM

Similarly and I extended to think about a dryer with a humidity sensor; it doesn't measure time well, it measures complexity, it gets more accurate the longer it works on the task, but the last progress meter can still take significant time with significant clothes.

Even if the estimate is correct - end of time and chime does not mean you can open door as it's still locked ;D

Yes, so did I. My washing machine that died a few weeks ago lied about it all the time. The replacement doesn't display the time at all, which made me think at first I should have paid more for one that does... which just goes to show why the manufacturers do it!

Time estimation which continually gets updated and doesn't inform you about the drift of the original estimation and actual time, nor when it was actually used vs finish time.

There's some humor in the parallels with software development.

Same. My (fairly modern, ~3 yo?) Husqvarna only show lies; it can show seven minutes left for ~30 minutes and then go straight to 0.

Same, I am constantly amazed how the estimate changes during runtime, especially at the Ende of the cycle…

Biggest cause of the estimate being wrong is the machine trying to balance the load for the spin cycle. It's basically brute forcing it by tossing the clothes over and over again until it's all balanced enough for the spin cycle.

This can take hours, or even fail altogether and then you're left with sopping wet laundry.

Yeah same, Having watched my machine give interesting time estimates while it was broken. I was hoping it was more about how it added up each task it was trying to do until it had to re do a task.

Same here. And yeah, I know its a shifting estimate, but it still always reminds me of the old "Windows minutes".

The most amazing of which is that it used to install faster if you jiggled the mouse.

jiggling the mouse generates random data. The installer uses this for all kinds of things. Some older versions of gnupg also stated 'please move the mouse' while generating your key pair just to have access to more random data :)

Reply on news.ycombinator.com