Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Show HN: Elevators

john.fun

Post reply on HN
Print view View original

221–230 of 426 posts

Re: Show HN: Elevators

#221

Post by qurren »

olex wrote: post #17

The biggest problem I always have with elevators is not the algorithm, it's the people seemingly being unable to grasp the concept of pressing either the up or the down request button, depending on where they want to go. Almost always I find someone will press both, because "then the elevator comes faster". Completely ignoring the fact that they end up going the wrong way first half the time, and adding an unnecessar…

I often enter it in the wrong direction.

Like let's say elevator is at 5, I am at 1 wanting to go to 3, and before I arrive there is already someone else at 1 wanting to go to -1.

I'll get in with them going DOWN so that it doesn't have to stop a 2nd time on the way up.

There are also other situations where I'll press it in the wrong direction if I think it's already likely to stop on the way down (due to me being on a popular floor) to save an extra stop on the way back up.

Re: Show HN: Elevators

#222

Post by esikich »

vachina wrote: post #72

Anybody knows what algorithm HITACHI is using on their elevators? Their elevators feels most “responsive” in high rises.

I can't imagine any elevator just uses a set algorithm. I'm sure after installing, technicians work with facilities for a period to dial it in as every building will have different needs and traffic patterns.

Re: Show HN: Elevators

#223

Post by ed_mercer »

Elevators drive me crazy. One of the worst sins I've seen is an elevator that says, “Sorry to keep you waiting,” while continuing to hold the doors open for the entire sentence. Just be quiet and close the doors already.

Re: Show HN: Elevators

#224

Post by paradox460 »

dbcurtis wrote: post #83
orliesaurus wrote: post #4

Oh my god, every time I'm waiting for the elevator, I think of how annoying it must be to be someone who's building the algorithm to make sure that you minimize the amount of wait times between picking up people and taking them to their destination. Then I also wonder if the people who apply the logic and program the logic into the elevators are actually evil sadists that are doing it on purpose to make us wait longe…

I have done several third-party elevator integrations (software that talks to the elevator controller) for coordinating other equipment with the elevator. One thing that always struck me once I had full visibility into the location and motion of all the elevator cabs is how busily they are scheduled. Waiting in the elevator lobby for a cab seems to take forever, but viewed from the dispatch side, it is a flurry of ac…

Some older buildings in SF have the old school elevator panels in the lobby, with big vertical displays of all the floors, and a moving needle for each cab, and lights where there were calls. Big beautiful brass monster, polished to a shine. I think it was the flood building. Used to love watching it on my way up

Re: Show HN: Elevators

#225

Post by Rebelgecko »

StableAlkyne wrote: post #104
orliesaurus wrote: post #4

Oh my god, every time I'm waiting for the elevator, I think of how annoying it must be to be someone who's building the algorithm to make sure that you minimize the amount of wait times between picking up people and taking them to their destination. Then I also wonder if the people who apply the logic and program the logic into the elevators are actually evil sadists that are doing it on purpose to make us wait longe…

> minimize the amount of wait times between picking up people and taking them to their destination I wish elevators accounted for load. I've been to a couple of larger conferences where on the Monday morning after, the hotel elevator was just hammered. Everyone wanted to go down, and the elevator would dutifully stop on every single floor no matter how full it was. If you were mobility disabled on the 2nd floor, you…

Some elevators have sensors that'll bypass pickups after a certain point. Super helpful for furry conventions

Re: Show HN: Elevators

#226

Post by fragmede »

cyberax wrote: post #116
neutronicus wrote: post #21

Earlier quoted context omitted.

They might have other objective functions like wear-and-tear on the elevators, total energy usage, or something

Modern elevators have regen braking, so they can recover most of the energy spent on going down. Older elevators used braking resistors for that. (BTW, going _down_ while empty is typically more energy-consuming for the elevators because they are counterweighted) Edit: that's also why you shouldn't use elevators in a fire. If the brakes in the elevator machine room fail, the cab won't crash down. It will go _up_, pos…

Interesting! It's counterbalanced though, so why does it go up if the brakes fail in a fire? That's counterintuitive.

Re: Show HN: Elevators

#227

Post by rrr_oh_man »

> Another metric you can track is journey time, how long you're actually waiting in the elevator before getting to your floor. RSR and LOOK have different characteristics here as well but that's beyond the scope of this article.

AAAAAAAAAAAH. WHY.

Re: Show HN: Elevators

#228

Post by dillutedfixer »

jp191919 wrote: post #11

Reminds of something I haven't thought about in a very long time... SimTower

If you want a trip down memory lane, go to InfiniteMac.org, spin up a System 7.5 emulator, go to the InfiniteHD/Games folder and launch SimTower!! Such a fun blast of nostalgia. I loved the game as a kid and can still very much enjoy it as a mid-40 year old.

Re: Show HN: Elevators

#229

Post by liesliy »

peterldowns wrote: post #78

Back in highschool, simulating different elevator algorithms was one of the projects I implemented during my CS class. It wasn't for the class — AP CS did not require anything like actual programming — but it was a fun project. A cool connection is that a spinning-disk hard drive (HDD) is actually kind of like one really long elevator, just wrapped around a spindle instead of perfectly vertical. The SCAN algorithm is…

The elevator algorithm → disk scheduling connection is such a perfect example of how CS concepts keep showing up in unexpected places. Same idea, completely different domain. It makes me wonder how many other "unrelated" problems we're solving today already have decades-old algorithms waiting to be rediscovered for them. Robot motion planning is basically just elevator scheduling with more degrees of freedom.
Post reply on HN