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Comment by elaus | Hacker News Reader

I don't really see how the vacuum can effectively clean a whole room or flat using only a CNN of the current image in front of the robot. This would help detect obstacles, but a bumper sensor would do that as well.

All but the most basic vacuum robots map their work area and devise plans how to clean them systematically. The others just bump into obstacles, rotate a random amount and continue forward.

Don't get me wrong, I love this project and the idea to build it yourself. I just feel like that (huge) part is missing in the article?

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https://opencv.org/structure-from-motion-in-opencv/

Not saying that it’s viable here to build a world map since things like furniture can move but some systems, e.g. warehouse robots do use things like lights to triangulate on the assumption that the lights on the tall ceiling are fixed and consistent.

The classic Roombas from a decade or so ago worked without any sort of mapping or camera at all -- they basically did a version of the "run and tumble" algorithm used by many bacteria -- go in one direction until you can't any more then go off in a random new one. It may not be efficient but it does work for covering territory.

I think the only reason for mapping is to be able to block off 'no go' areas (no escaping out the front door!) and to be able to go home to the charger.

For the actual cleaning, random works great.

You are right. The original Roomba was discussed on HN 3 months ago:

https://news.ycombinator.com/item?id=46472930

Surely mapping also helps reducing the time it takes to achieve the task?

A robot vacuum isn't time constrained. It literally has all day.

They make noise, and people remote, so that might not be the case.

In addition, more working time equals more wear and tear for parts.

my previous robot vacuum did not do any mapping, but did always manage to find its way back to the charger. It'd just follow the walls until it saw the chargers IR beacon.

Clever design if you ask me. Doing a lot with a little.

Sounds like it would only work for a single room with not too many obstacles.

I guess the mapping capabilities vary greatly between vendors. I had a first gen Mi Robot vacuum and it was amazing. It would map the entire floor with all the rooms, then go room by room in a zigzag pattern, then repeat each room, having no issues going from one room to another and avoiding obstacles. It also made sure not to fall down the stairs. Then later it broke and I bought a more noname model and despite having lidar tower, it didn't perform as well as Xiaomi vacuum did. It worked for a single room, but anything more and it would get lost.

Eh, it worked fine in my multiroom apartment - again, this is how all first generation robot vacuums worked. Mine eventually died and I got a new one with lidar, and the main adventage is that with mapping I can specify areas to avoid like a chair whose base tends to trap robot vacuums.

They're terrible. A $200 SLAM equipped vacuum (like open box or something off eBay) will do in 15mins what those took an hour to do

Apart from just detecting obstacles, we wanted to build a robot which is intelligent enough to take in semantic cues like this is a doorway so I can go through it, or this is a kitchen I can clean it this way and so on

There was a time when they were all what you consider basic, and they could still clean a whole room or flat.

It navigates by Brownian motion.

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