One Cool Day Job: Building Algorithms For Elevators

McGruber writes "The Wall Street Journal has an article about Theresa Christy, a mathematician who develops algorithms for Otis Elevator Company, the world's largest manufacturer and maintainer of people-moving products including elevators, escalators and moving walkways. As an Otis research fellow, Ms. Christy writes strings of code that allow elevators to do essentially the greatest good for the most people — including the building's owner, who has to allocate considerable space for the concrete shafts that house the cars. Her work often involves watching computer simulation programs that replay elevator decision-making. 'I feel like I get paid to play videogames. I watch the simulation, and I see what happens, and I try to improve the score I am getting,' she says."

Comments

maybe they should release it as a game

[Trepidity]

'I feel like I get paid to play videogames. I watch the simulation, and I see what happens, and I try to improve the score I am getting,' she says.

I've been looking for a more sophisticated follow-up to SimTower for a while now. I'd buy Otis Elevator Tycoon.

Re:maybe they should release it as a game

[Anonymous Coward]

You got modded funny, but SimTower was an awesome game and I totally agree with you.

Re:maybe they should release it as a game

[westlake]

I've been looking for a more sophisticated follow-up to SimTower for a while now. I'd buy Otis Elevator Tycoon.

This gets modded up as a joke, but the interaction of tech and people within a mega-structure seems to me a solid foundation on which to build a game. But I can think of only Sim Tower and Startopia as examples.

Re:maybe they should release it as a game

[Anonymous Coward]

It would be a great android/iphone game. A bit like sushi chef games.

Re:maybe they should release it as a game

[plover]

Actually, long ago I remember reading the story of SimTower, and it actually started out as an elevator simulator research tool! It turned out that the simulator was so much fun to play that someone had the bright idea to morph it into a video game.

Re:maybe they should release it as a game

[the_rajah]

I designed the hardware and wrote the code for a much smaller elevator company for 25 years... All written in assembly language running on an 8085 CPU with 256 bytes (Yes, bytes) if RAM and 8K bytes of EPROM. It doesn't take much to handle the basics when you're using assembly language. I've done up to 26 stops in a multi-car group with that setup. Each elevator is independent and can run on its own, but they communicate with each other to handle dispatching so multiple cars coordinate their activity.

Optimizing is worthwhile, but adds a lot of complexity. You have to take into account for car locations, direction, speed, where car and hall calls are locatedand have to figure in such things as door times to calculate which car can service a hall call soonest.

As the author says, it's a set of interesting problems and I've had fun with it. Yes, the equipment I designed and wrote the software for is obsolete now, but there's a lot of it out there so I'm anticipating writing updates for a while longer as I head toward eventual retirement.

Re:maybe they should release it as a game

[anubi]

I sure wish cities would hire guys like you to work on their traffic lights.

I highly question whether or not anyone pays any attention at all to the timings of these things; It seems that they would have more luck getting anyone who has ever milked a cow to design one, as they would have some inner sense as to how timing results in smooth flow. Improperly time your efforts and you get no milk and infuriate the cow.

( You can tell where I was raised here ).

Re:maybe they should release it as a game

[T-Ranger]

I'm not sure about that, but the original Sim City *was* based on Will Wight's previous project, Raid on Bungeling Bay. Or rather, how his Bungeling Bay map editor was as much fun as the end game.

Re:maybe they should release it as a game

[cynyr]

In my case, the lights on a local hwy are sync'ed for good driving by the city. The issue is that every time you cross city lines (about 4 times in 6 miles) the timing changes again.

I have also heard stories where there was pressure on the city to raise the speed limit from say 45MPH to 50MPH for a bit of road. Well the city gave in and raised the limit, but didn't change the timing. Driving the speed limit will get you stuck at lights, but driving the limit the city wanted it to be will mean lots of greens. There are roads around here where this is the case, 5 under and you hit every light green, so I mostly believe the story.

Re:maybe they should release it as a game

[Shinobi]

As the parent mentioned, timing involves multiple cars. It's the same thing in optimizing traffic light timings, they can't just factor one direction on a single road. You have to consider parallell roads, crossing roads, highway on- and off-ramp locations and all the traffic loads and the resultant traffic flow patterns. Needless to say, for even a moderate-size city, it's an incredibly complex problem.

Re:maybe they should release it as a game

[Culture20]

It's usually the other way around. The lights are timed for 5-10 miles over the speed limit, and cops use it as a constant stream of speeders for ticketing.

Re:maybe they should release it as a game

[Anonymous Coward]

Playing with the elevator scheduling in SimTower was the best part

Re:maybe they should release it as a game

[toddestan]

I can believe that, as your tower eventually grows to the point where you're pretty much screwing around the elevator system the whole time, which is pretty much the point where I get bored with SimTower.

Re:maybe they should release it as a game

[tlhIngan]

I sure wish cities would hire guys like you to work on their traffic lights.

I highly question whether or not anyone pays any attention at all to the timings of these things; It seems that they would have more luck getting anyone who has ever milked a cow to design one, as they would have some inner sense as to how timing results in smooth flow. Improperly time your efforts and you get no milk and infuriate the cow.

The problem is light timing is a very hard problem. First off, take a basic city with a grid style street layout. You can optimize the greens for flows in certain directions, but then the cross streets often get blocked up because they don't have an optimized pattern.

You can try optimizing flows differently - perhaps two get timed greens southbound because everyone's heading home (and they turn northbound int he morning rush), while a third street goes the other way. If you go southbound on that, you'll hit lights (and it's actually faster to navigate to the other streets than taking a direct route). Yes, the longer way can be faster because only some streets have timed lights in order to not cause total gridlock looking for an optimal solution. The goal is to find which ones are timed in which direction at what times (because the primary flow differs due to morning and afternoon rushes), and to see if the time it takes to navigate to the longer but timed routes is faster than the time it takes to go by the obvious route. In some places, the lights are timed in a circle (one street north, one street west, one street south, one street east) so choosing the optimal path may mean going the opposite direction to join it quicker.

Next, you have complications like parking, left/right turn lanes/lights/not-allowed. And idiot drivers who floor it at the green to hit the red in front, or more likely, those who see the light ahead is red, and don't move much above creeping speed to not have to slow down much.

And the lights are also timed to a speed - a road with a limit of 40 might have its lights timed to 30.

And yes, city planners have a headache of it all - allow a bicycle lane here, mess up traffic there, roadwork forcing diversions, etc. Illegal parkers and pickup/dropoffs don't help, either.

Elevators are easy - when making decisions, you have all the information ahead of who - who's calling for an elevator, and which floors the elevator must stop at. Some more intelligent systems may even schedule elevators by requesting that those who call an elevator enter in their destination floor as well.

Re:maybe they should release it as a game

[Jedi Alec]

I just drop the rent on offices to the point where everybody's happy, even if they're profoundly miserable from standing in line for 3 days.

Re:maybe they should release it as a game

[TheLink]

You have to take into account for car locations, direction, speed, where car and hall calls are locatedand have to figure in such things as door times to calculate which car can service a hall call soonest.

I wished more elevators took into account how full they were. There's no point having a full or near full elevator serving external requests. A full elevator should only do internal requests. An elevator might guess how full it is by the load it is carrying, or even whether anyone got in for a previous request (door opened but nobody got in- load stayed the same and is high, but the request button was pressed again soon after the door closed - which normally means there was someone there but he/she did not go in despite wanting an elevator).

Nice to have but not so important would be a standardized way to cancel requests.

Nowadays I think some elevators are on "least energy used" and not "fastest service" at least based on the way they seem to behave...

Re:maybe they should release it as a game

[Anonymous Coward]

Elevators are Not easy. We have a system like that, where you enter your destination floor. 31 floors but its divided into two sides. South does 1-17, north does 1,2,3 and 17-31 (canteen is on 3). 6 elevators on each side.

During the lunch rush this system doesn't work at all. People tend to just use the first elevator that goes to their destination. Which means, the elevator coming down from 30 will be full when it reaches, say 27, even though the system scheduled a few people on 26, some on 24 and some more on 20. Obviously those cant squeeze in any more and will hit the destination buttons again hoping for better luck next time. They may also jump into another elevator that's not yet full. Obviously during lunch most people go to 3 (canteen) or 0 to eat out. Try getting from 30 to 14 and you are better off walking down.
Also, this practically means that most elevators just stop on just about every floor, as people frantically type in destinations over and over in order to try and get an elevator. The problem is, that the system has an SLA of a second or so, in which it has to assign an elevator to someone, so bookings tend to not be optimal anyway and then people screw even that planning by jumping into the wrong cars.

Sounds pretty complex to me

Re:maybe they should release it as a game

[Anonymous Coward]

Your mistake is that you think the lights and their timing is actually there for your benefit. Much like Facebook and Google your are actually the product $$$ or the means of production $$$.

Re:maybe they should release it as a game

[AmiMoJo]

Mitsubishi elevators do that, using a camera and image recognition to see how packed the car is.

They also optimized the door opening and movement sequence a lot. In newer ones if you watch carefully the doors close fairly quickly, then right at the last moment slow down and gently shut so that any trapped fingers won't be harmed. At the same time the car also starts moving and you can see the floor outside rising/falling. It only saves maybe two seconds but in a busy building with many floors that makes a big difference.

They also make high speed escalators, and escalators that only run when people are using them and roll to a halt when not needed.

Re:maybe they should release it as a game

[tconnors]

I sure wish cities would hire guys like you to work on their traffic lights.

Yep, the hick that designed your traffic light sequencing system obviously didn't have years of training required to work with a highly complex distributed system:
http://xkcd.com/277/

Re:maybe they should release it as a game

[Meski]

Overdesigned UI. All you need is up or down.

Re:maybe they should release it as a game

[Anonymous Coward]

I worked for US Elevator in the early 70s. Another manufacturer (I forget which) incorporated three load-weighing switches beneath the floor of the cab. The greater the occupancy, the greater the floor flex, and the more likely that the car would ignore 'hall call' requests. BTW, most high-speed elevators begin opening the doors when 5-6 inches from the final 'leveling';. It's been that way for decades; the building code allows it.

Re:maybe they should release it as a game

[Neil Boekend]

Remember, if the lights are optimized for a given speed V then it's also optimized for 0.5*V. That does have the slight disadvantage that everyone else on the road feels that you are a moron of you do this, and the accident risk will probably rise, but it works.

Re:maybe they should release it as a game

[Neil Boekend]

Doesn't an elevator know approximately how many people there are in it based on the weight of the cart? Plus it knows what the destinations of all people inside are.
So if everyone in it wants to go to 3 or 0 and the elevator is full when it's on 27 then it shouldn't stop on 26-4, but it should just go on to 3 as fast as the limits allow so the elevator can get empty on 3 an 0 and go back up to pick new people up.

Re:maybe they should release it as a game

[stonecypher]

The problem is light timing is a very hard problem

It is not even slightly difficult to beat today's results with a simple annealer. I would *love* for someone to pay me to fix this.

Re:maybe they should release it as a game

[AdamWill]

"Doesn't an elevator know approximately how many people there are in it based on the weight of the cart?"

Weight of human beings varies from about 5lbs right up to 800lbs, so, no. Even if you discount people unlikely to be old enough to be making their own floor decisions, a very thin/short person can easily weigh in well under 100lbs, or 1/8th of a Biggest Loser candidate...

Re:maybe they should release it as a game

[ockegheim]

But the thin/short person and the Biggest Loser candidate are outliers, so unless there is a weight-loss convention or a supermodels’ meeting, you can derive the number of people from their weight reliably enough for these purposes.

Re:maybe they should release it as a game

[Neil Boekend]

It doesn't really matter. One 400 kg (approx 800 pounds) man is enough for an elevator. 8 people of 50 kg (approx 100 pounds) is also enough.
True that does mean the elevator doesn't know how many people are in the cart. But it does know if the cart is full.

Harddisks use something like it

[Anonymous Coward]

https://en.wikipedia.org/wiki/Elevator_algorithm

* Thought that might "pique" a few folks' interests...

APK

P.S.=> However - I'd wager that MOST of you know about this though... Especially the "hardware heads" into hard disk drives!

... apk

Re:Harddisks use something like it

[Anonymous Coward]

I'd wager that MOST of you know about this though

This is a statement I thought I'd never see on Slashdot. You must be new here.

Re:Harddisks use something like it

[Sir_Sri]

That's an undergraduate level general optimization problem.

The one in TFA is a graduate level optimization under a particular set of data constraints. So the generally optimal algorithm for elevators has to a assume a random distribution of people to be picked up and destination floors (head is in a random location wants data from some other random location) - but in practice you may be need sequential access or the like. With elevators, I would expect that in mornings in residential buildings people want to empty out so the 'resting' point would to close to 2/3rds or 3/4ths of the way up, but in the evenings it would be the reverse direction, and business would be the reverse of residential. Schools have a somewhat more random use of bursty every hour up and down, and really big businesses may want dedicated elevators between floors shared by particular companies because there's a lot of daily movement within the floors of a company but not so much outside their area.

Lunch of course adds another complication.

There's a lot of neat work into simulating the data for a building that doesn't exist yet, or measuring the data for a building that exists but has a bad algorithm. And then trying to tailor your elevator to the specific behaviours that actually exist.

Re:Harddisks use something like it

[Anonymous Coward]

Nevertheless it's similar and has variants that work better in different scenarios/circumstances. Your point's what?

Re:Harddisks use something like it

[ShanghaiBill]

So the generally optimal algorithm for elevators has to a assume a random distribution of people to be picked up and destination floors

It seems to me that assuming a poisson distribution) or other random distribution, is a bad assumption. Passengers would be likely to arrive in clumps as meetings ended or buses arrived, and some destination floors would be far more popular than others

One thing that would help, but I have never seen, would be a way to cancel a button push (either the call button, or a floor button inside the elevator). Buttons are often pushed in error, resulting in wasted time.

I once heard a funny story about an engineer assigned to optimize an elevator system. The building supervisor had received numerous complaints about the elevator delays, so he told a young engineer to fix the problem. The engineer tried several adjustments, but still had just as many complaints. So he had mirrors installed next to each elevator, so people could adjust their hair, tie, clothing or whatever while they were waiting. Since people now had something to do while they were waiting, most of the complaints stopped.

Re:Harddisks use something like it

[Anonymous Coward]

To describe the particulars of this problem that go beyond the well-known elevator algorithm.

I know it's the Internet, but still. Don't be a jerk.

Re:Harddisks use something like it

[Sir_Sri]

It seems to me that assuming a poisson distribution [wikipedia.org]) or other random distribution, is a bad assumption.

it definitely is a bad assumption.

But if you are trying to solve the general problem of where to position an elevator or a disk head in general you have to. That's why it's an 'undergraduate' level problem. The serious research today comes in knowing what the real data will be like, and whether or not you can optimize for real data rather than an average best case for any arbitrary data set.

Re:Harddisks use something like it

[swillden]

I'd think some really interesting things could be done with machine learning. A truly optimal elevator control system would be one that adapts itself over time.

Re:Harddisks use something like it

[hairyfish]

I got given this problem as an undergraduate about 20 years ago, and ever since then, every time I get in an elevator I try to think of ways to make the logic better. In 20 years I still can't figure one out because every situation is different. My current building is 12 stories with 3 elevators. There is a basement which is only served by one of the three elevators, and the top floor is the Exec level which gets priority (one lift homes to this floor). My last building was 10 floors, half of which was a mall, the other half offices. It had 8 elevators that did different things on different floors depending on where you were coming from and where you are going. Before that I worked in a 40 storey building which had the standard four lots of lifts that service 10 floors each. In summary this is not an undergraduate problem. For a one-off fixed set of circumstances it might come across as a simple undergrad issue, but the reality requires a bit more expertise.

Re:Harddisks use something like it

[Smauler]

One thing that would help, but I have never seen, would be a way to cancel a button push (either the call button, or a floor button inside the elevator). Buttons are often pushed in error, resulting in wasted time.

And also you've got to take into account the fun kids could have cancelling everyone's requests, and sending them back to the ground floor :)

Re:Harddisks use something like it

[Anonymous Coward]

Then you detect a science-fiction convention, because the elevator controller melts. This really is true, science-fiction conventions are often very effective at causing elevator controllers to display many kinds of highly sub-optimal behavior.

At a Westercon in Seattle, they discovered the control software was written by the Japanese. You're supposed to be polite and never stop an elevator departing my triggering the door sensors, if you did the elevator would shut down a while later. With most functions on floors 1-3, but parties on 36-38, and Art Show and/or Con Suite on the 40th, the elevators got a workout. At a different convention elevator calls kept being dropped. The hotel was in some ways happy since they'd noticed the behavior before, but never had is show up well enough to track down the cause. Turned out the 256th elevator call was being dropped...

Oy vey, do you get to watch hotel elevator controllers melting during conventions.

Sounds good but . . .

[Anonymous Coward]

I expect the job has its ups and downs just like any other.

Re:Sounds good but . . .

[Anonymous Coward]

As long as she doesn't fall to pieces, she'll survive.

Re:Sounds good but . . .

[Hognoxious]

Careful, I hear it's easy to get shafted.

Re:Sounds good but . . .

[Anonymous Coward]

You can't put a whole profession in a box.

Re:Sounds good but . . .

[davester666]

Just don't push her buttons!

Re:Sounds good but . . .

[Delarth799]

Sometimes you need to think outside of the box

Re:Sounds good but . . .

[Anonymous Coward]

I bet she freaks out when a VIP arrives to the building that she is working on.

Re:Sounds good but . . .

[SeaFox]

Yes, but for every door that closes, a new one opens elsewhere.

Re:Sounds good but . . .

[Anonymous Coward]

I expect the job has its ups and downs just like any other.

When I got to MIT, the Lobby 7 elevator still had a human operator. He was a genial older gentleman, if you asked him, "How's it going?", this was his stock answer. A year or two later he retired and the elevator was automated (c.1973).

Re:Sounds good but . . .

[bobzieruncle]

Yeah, but Otis Elevator is good to the last drop. :-D

Code that must "never crash", no?

[dryriver]

I'm guessing that the hardest part of the job is writing code that does not crash, possibly leaving elevator riders stranded between floors, or going up when they want to go down. Over the years Otis must have developed a pretty good elevator usage simulator that plays through millions of possible elevator use scenarios, and tries to find one that either crashes or confuses the system. If yes, the developers responsible for that "possibility simulator" should have been named in the article alongside "The Elevator Algorithm Lady". They should have gotten some credit where credit is due...

Re:Code that must "never crash", no?

[Anonymous Coward]

News flash: State machines don't crash.

Re:Code that must "never crash", no?

[Anonymous Coward]

She probably just writes the logic part not the code that realizes that logic. The actual code will be a finite state machine with certified logic blocks. Those dont crash.

Re:Code that must "never crash", no?

[Animats]

Each elevator has its own controller, which is relatively simple. When there's more than one elevator, there's also a group controller, which makes the decisions about which elevator responds to which call. All the smarts are in the group controller.

Many elevators have a key switch for "independent service", which disconnects them from the group controller. Then they only respond to the buttons in the car. The group controller isn't necessary to basic elevator operation.

Re:Code that must "never crash", no?

[amorsen]

Elevator software is probably the most obvious use case for software with correctness proofs. Note that the elevator going up when you want to go down is not necessarily bad programming, the most efficient place to go next is not necessarily where the last person who entered the elevator wants to go.

Re:Code that must "never crash", no?

[Lehk228]

it really just needs a very simple core of functions certified and an interface that less tested code can use to control it.

parts that need to be a certified finite state machine

detect when at a floor and open doors only at safe times (when stopped at a floor unless overridden by fire key) and detect when car is over weight limit detect when fire alarm is active

parts that need to be really damned good code: always travel to specified floor number

parts that can be done with PHP and javascript if you want: deciding what order to go in to maximize effectiveness, if it gets it wrong worst case scenario is people get pissy and use the stairs, burn some calories

Re:Code that must "never crash", no?

[Anonymous Coward]

Note that the elevator going up when you want to go down is not necessarily bad programming, the most efficient place to go next is not necessarily where the last person who entered the elevator wants to go.

Most elevators I've seen have a pair of lamps on each floor that show the direction the elevator will go next. If you push the down button but the door opens with the up lamp on, you just don't get on (unless you like spending extra time in an elevator with other people).

Re:Code that must "never crash", no?

[the_rajah]

I did all my elevator in assembly language, Sonny. (Seriously) Now get off my grass.

We don't use the term "crash" when talking about elevators.

Re:Code that must "never crash", no?

[davidbrit2]

If it's anything like traffic lights, there's probably an independent controller/program to watch for invalid states, and immediately disable the fancy logic and switch to a simple failsafe mode. Honestly, the demands are probably less than with traffic lights. (Bad green lights could kill people, but an indecisive elvator would probably be a nuisance at worst.)

Re:Code that must "never crash", no?

[__aaltlg1547]

No, but they can get stuck in useless modes.

Re:Code that must "never crash", no?

[maxwell demon]

That depends on how you define "crash". If you define it as abnormal program abort, then no. But if you consider the program just sitting there and doing nothing useful to be a crash (indeed, during DOS times, that was the typical way programs crashed), then a state machine can easily crash.

Re:Code that must "never crash", no?

[maxwell demon]

Note that the elevator going up when you want to go down is not necessarily bad programming

It is usually bad input: People who press both the "up" and the "down" button to make the elevator come sooner.

Re:Code that must "never crash", no?

[fa2k]

The lifts at my workplace sometimes stop right at the floor I am, but stays there without opening the door for 30 seconds or so. I suspect the microcontroller crashes and recovers.

Re:Code that must "never crash", no?

[amorsen]

Generally when it happens to me it is a race condition, the elevator was idle but someone presses "summon" before I press "go".

Once in a while I will board an elevator going in the wrong direction to exploit the fact that many elevators consider getting people already inside to the right floor more important than serving passengers who are not on the elevator yet. That is antisocial of me, of course.

Re:Code that must "never crash", no?

[Anonymous Coward]

News flash: you write Java, don't you?

State machines, such as relay based systems, are often left by newbie designers with "unaddressed" states that freeze the system or enter an endless loop completely outside the normal operation cycle. These states can commonly occur with voltage drops or power ups for the system, and they're why someone with a clue takes so much longer designing the system.

This is like the ghods-awful Perl, Java, and database code that assume because the spec for the code called for a well defined set of input values, that those are the only values you will ever get. They refuse to properly handle non-standard data, and the resulting chaos are why the engineer in the oritical article gets paid: because "state machines don't crash" is like saying "computers are binary, so show me the bit that caused the error". It shows a fundamental lack of comprhension about both computing, and about the nature of reality.

Re:Code that must "never crash", no?

[AmiMoJo]

True, they just screw up in other undesirable ways like getting stuck in an infinite loop or one particular state.

Re:Code that must "never crash", no?

[markxz]

I used to work in a building where the lift controller would crash (not respond to any buttons), a hard reboot usually sorted it for a while.

It usually went down after people abused it by holding the doors open for too long.

It was an Otis built in the early 2000s

Re:Code that must "never crash", no?

[markxz]

It is usually bad input: People who press both the "up" and the "down" button to make the elevator come sooner.

The best way to solve this is to make the interior buttons reject floor selections which are not in the direction of travel (accompanied by a warning siren and message to help educate the retarded user)

Re:Code that must "never crash", no?

[Meski]

If you had an elevator with AI, it might be afraid to go up... Damn, what was that? Hitchhikers Guide, or a Dirk Gently?

Re:Code that must "never crash", no?

[tlhIngan]

It is usually bad input: People who press both the "up" and the "down" button to make the elevator come sooner.

The best way to solve this is to make the interior buttons reject floor selections which are not in the direction of travel (accompanied by a warning siren and message to help educate the retarded user)

A lot of elevators do that - if the button pushed is going in the wrong way, they don't allow it to light up.

Then I've seen ones that do allow you to push it, but it will continue that way until the bottomost floor is serviced (and no one else needs the elevator to go down) before it changes direction. But then it then services everyone going up, including the original up request (if no other elevator serviced it yet).

The trickiest I seen was it let you push the button, but once it stopped going down (if you wanted it to go up), it cleared all the selections and idled. If you push a lower floor, it went, if you push a higher, it doesn't move (parked). If you push the current floor, it reopens the door. It won't change directions unless there was a reason for it to (e.g., ground or top floor)

Re:Code that must "never crash", no?

[stonecypher]

Elevator software is probably the most obvious use case for software with correctness proofs.

And here I would have thought it would be things where loss of life could follow failure.

If (hospital elevator)

[GoodNewsJimDotCom]

If(weight in elevator if(almost every floor pressed)
{
emit_audio_tone("Hey kid cut that out, people's lives might be at stake because you're playing in a place you shouldn't be playing.");
call_security("Kid pressed all the elevator floor again, go embarrass him to his parents.");
clear_all_floor_buttons();
}

Re:If (hospital elevator)

[GoodNewsJimDotCom]

if(weight in elevator less than 200) My less than symbol got nixed because it was thinking I meant hypertext markup

Re:If (hospital elevator)

[GoodNewsJimDotCom]

I just realized something else, everyone would be playing with the elevator even more if it talked to you... so maybe it isn't a good thing to emit a sound... Maybe just call security.

Re:If (hospital elevator)

[Anonymous Coward]

Most hospitals have multiple sets of elevators and one or two are reserved for patient transport.

Re:If (hospital elevator)

[tftp]

My less than symbol got nixed because it was thinking I meant hypertext markup

You are welcome to use this one: < (written as &lt; - all four characters required.)

Mathematician?

[hawguy]

Was a mathematician really needed for this job:

During the recent $550 million upgrade of the Empire State Building, Ms. Christy was asked whether she could help get more people up to the observation deck. She said she couldn't get more people into a car but could move them up more quickly. So she increased the elevators' speed by 20%, to 20 feet per second. Now the cars can rise 80 floors in about 48 seconds, 10 seconds faster than before.

Isn't making the elevator go faster a job for an engineer? Does one really need to be a mathematician to know that a faster elevator moves people faster?

Re:Mathematician?

[Zontar The Mindless]

Velocity and frequency are not the same thing, and 'faster' does not necessarily mean 'more frequently'.

Re:Mathematician?

[Anonymous Coward]

A computer programmer will do http://hardware.slashdot.org/comments.pl?sid=3287917&cid=42156255

Re:Mathematician?

[MachDelta]

Should be a CS job, really. All you need to do is modify the speed-up loop.

Re:Mathematician?

[Hognoxious]

It might be one of those weird things where the faster it's going the longer it takes to come to a stop, so going faster makes sense if there are calls from fewer floors but not if someone wants to board at every one. Or something.

Re:Mathematician?

[Samantha Wright]

A professor once described to me an elevator system at his former place of employment that used machine learning to try and anticipate where the elevator should be when not in use. At the start of the day, for example, the elevators should rest on the ground floor, so that they can collect people going up; similarly, toward the end of the day, they should rest at the top, since the overwhelming majority of people would be going down.

In a real-world setting you may have other phenomena that actually need to be learned, such as different groups taking lunches at set times of day, large meetings that cause several floors to congregate on one, et cetera. This problem can be considered from several different angles within ML; either as a regression problem or classification, for example.

Speed also needs to be optimized not just based upon the desire to reach the destination quickly, but also considering the rate at which the mechanisms will wear out, the energy consumption caused by more rapid movement, and to encourage people to use the stairs.

Given the potential complexity of how many parameters and models can potentially be considered... yeah, you want someone with a serious background in applied optimization, statistics, or artificial intelligence.

Re:Mathematician?

[Anonymous Coward]

There is probably a trade-off of lift capacity vs. velocity. i.e. Given the same means of propulsion, (put crudely) you can lift fewer people fat higher velocity or more people at a slower velocity.

The "faster" the building owners are interested in is probably the number of passengers per unit of time that can make it to the observation deck, not the duration of any one single trip of the elevator car.

I am neither an engineer nor a mathematician!

Re:Mathematician?

[Anonymous Coward]

Not sure if you were really trying to say that this job was for a man instead of a woman....

Re:Mathematician?

[Florian Weimer]

Isn't making the elevator go faster a job for an engineer? Does one really need to be a mathematician to know that a faster elevator moves people faster?

If the elevator can make stops along the way, it probably refers to mean travel time, and it's an entirely different problem.

That being said, the "surfboard feature" is really, really, old. A lot of elevators have on-demand overrides which prevent intermediate stops. So the article might just be an infomercial for the elevator company after all.

Re:Mathematician?

[dugjohnson]

But can she program A Happy Vertical People Transporter?
http://hitchhikersguidetoearth.wikia.com/wiki/Sirius_Cybernetics_Corporation

Re:Mathematician?

[vurian]

While you smell like someone who's had an abstract exercise in his first year and now knows everything about the problem area, just because you've never been hired to solve any real problems.

Re:Mathematician?

[Anonymous Coward]

My guess is that the elevator was using a general purpose algorithm before she changed it. If you know that the elevator is an express to the observation deck, you can accelerate to maximum speed without putting too much stress on it or wasting too much energy.

Re:Mathematician?

[Anonymous Coward]

Nah, that never happens.

Re:Mathematician?

[Anonymous Coward]

Elevator algorithms were pretty standard CS curriculum back when I was in college in the early 90's. This smells like another "Let's make women feel like they matter in technology by making a big deal out of something any halfway decent grad student can already do" type story.

Man I was with you until the second line. There's some latent woman-hate going on. What's the problem bro? Women turning you down too fast?

Re:Mathematician?

[Anonymous Coward]

I hope a mechanical engineer took into account the additional stress onto the elevator's cables, pulleys, guide rails and brake systems that a 20% increase in speed will cause... if this woman alone threw a number without taking into consideration the factors mentioned above, GOD help those tourists when one of those boxes fail.

Re:Mathematician?

[PPH]

Damn! Now I have this image stuck in my head.

Re:Mathematician?

[waveclaw]

A professor once described to me an elevator system at his former place of employment that used machine learning to try and anticipate where the elevator should be when not in use.

I wonder how a machine learning program deals with the 10 year old who thinks it is funny to press every single floor button then get off on a random stop. Usually when at least half the building's population is running 5 minutes late for their flight.

Re:Mathematician?

[samkass]

One fairly new building in south Manhattan has a system where you type the number you want to go to before entering the elevator waiting area, and it tells you what door to wait in front of. When the elevator arrives it lists the floors it will stop at. It seems to optimize for minimal elevator usage, minimal wait times, no overcrowding, etc. Once the elevator system has a little more information it can do a lot better.

Re:Mathematician?

[Idarubicin]

Isn't making the elevator go faster a job for an engineer? Does one really need to be a mathematician to know that a faster elevator moves people faster?

I suspect that the problem here is a failure on the part of the article writer. The author was probably just looking for any sort of answer to 'What's the most famous building you've ever done any work for?', rather than 'what's the most mathematically-interesting part of your job?'

It's also possible that there's a little bit of complexity being glossed over here. For the Empire State Building, visitors take up to three consecutive elevator rides to get to the observation decks: one to get up to the 80th floor, another from 80 to 86 and the main observation deck (though the hearty can take the stairs), and an optional, extra-charge trip from 86 up to the topmost observation area on 102. Visitors form queues for tickets, security, and each elevator ride (both up and down).

While speeding up any of the elevators might seem like a good thing, it runs the risk of causing crowding and bunching of passengers waiting for the now-overloaded next stage. Making one set of elevators faster could increase wear and tear on those elevators (and increase both energy use and passenger discomfort) without improving overall throughput; I can see how there might be some serious mathematical optimization going on there. As well, it's possible that our mathematician was involved in optimizing all of the building's elevator speeds and timings, and not just the elevators dedicated to observation deck service: a much more difficult optimization problem.

Re:Mathematician?

[Anonymous Coward]

Check weight at each stop and compare. If there's no change for 2-3 stops, reset all stops made from inside the elevator (but keep those made externally).

That's just something I thought of right now and it has obviously not been tested in practice. There might be problems with it.

Re:Mathematician?

[DiSKiLLeR]

That is pretty standard, we have those in New Zealand which is a pissy tiny little country.

Re:Mathematician?

[Anonymous Coward]

Women turning you down too fast?

They've optimized that, too.

Re:Mathematician?

[Anonymous Coward]

Barbara/tomhudson: Your work @ siemens & the "fine" SCADA controller code you did there doesn't qualify you to speak here.

Re:Mathematician?

[mbkennel]

Exactly, moreover there isn't any "optimal" solution.

This is an applied science & engineering problem. People will solve it by developing self-learning algorithms but based on methods, assumptions and data which are customized to the specific installation. Actual experience doing this for many years for paying customers is important. Methods need to be robust to changing assumptions and changing uses.

I work in machine learning and applications for business (not elevators). The real metric which counts is the very low-bitrate "phone call metric" --- how often do you get phone calls from unhappy clients.

"Good judgement comes from experience. Experience comes from bad judgement." -- Mark Twain

Re:Mathematician?

[steviesteveo12]

I suppose there's definitely no reason to stop the elevator for calls made inside the car if the car's at its unloaded weight (ie. empty). I think you don't want to start clearing instructions for UX reasons if there are people inside the car, though. I imagine face recognition technology could lead to situations of even identifying which passenger pressed all the buttons..

Re:Mathematician?

[tbird81]

Whereabouts? Granted, I don't work in an office tower, but I've never seen one. In fact, I don't actually think I've seen any smart elevators at all!

They just seem to respond to a call button, and go to the floors that people have selected. Once at the final floor the elevators just seems to hand around on the floor it stopped on. Same when I've travelled to the US.

The smartest thing I've seen elevators do is return the the ground floor (or lobby, or whatever the busiest floor is) to wait.

Re:Mathematician?

[CBravo]

It is actually a complex system if you want the ride to be as nice as possible. You want the g-force to be limited as wel as the jerk (time derivative of g-force which is what rocks you stomach) to get a nice fast ride. Without passengers you can use a different speed function which would be too uncomfortable for them. You might want to factor minimizing wear and tear in the function depending on the time of day.

Re:Mathematician?

[Anonymous Coward]

We have that system in a small ambulatory building in Spain. The building is pretty old.
Two elevators, four floors.

Re:Mathematician?

[Anonymous Coward]

Germany here (Frankfurt). We have a system like that, where you enter your destination floor. 31 floors but its divided into two sides. South does 1-17, north does 1,2,3 and 17-31 (canteen is on 3). 6 elevators on each side.

During the lunch rush this system doesn't work at all. People tend to just use the first elevator that goes to their destination. Which means, the elevator coming down from 30 will be full when it reaches, say 27, even though the system scheduled a few people on 26, some on 24 and some more on 20. Obviously those cant squeeze in any more and will hit the destination buttons again hoping for better luck next time. They may also jump into another elevator that's not yet full. Obviously during lunch most people go to 3 (canteen) or 0 to eat out. Try getting from 30 to 14 and you are better off walking down.
Also, this practically means that most elevators just stop on just about every floor, as people frantically type in destinations over and over in order to try and get an elevator. The problem is, that the system has an SLA of a second or so, in which it has to assign an elevator to someone, so bookings tend to not be optimal anyway and then people screw even that planning by jumping into the wrong cars.

Re:Mathematician?

[drolli]

The engineer knows how to make the elevator faster.

The mathematician knows how to make it move it less for the same result.

If both work together the effects multiply, since they are completely orthogonal.

As some physicist who converted to building control and analysis systems, i find it surprising how much mathematics you need to analyze the optimum point for control. It is even more amazing how complicated it is to predict the outcome of an investment, given different control strategies.

As it turns out, the biggest problem is the user. How much elevator movement could be saved if there would be a accepted way of informing the user that at certain times of the day they have to walk one stair down, but have a short waiting time? If you could inform them that accepting 18degree Celsius of room temperature instead of 20 for 2h would save a significant amount of heating cost? How can you increase the acceptance of (seemingly odd) decisions of the building control system? What kind of invasion of the privacy would users accept, in comparison to the positive savings of motion sensors in offices?

No, actually if you want to describe these things statistically (instead of trying to negotiate all of these things with the users), you need a mathematician, who will try to pack user behavior in distributions, correlations, and optimize for a given objective.

Re:Mathematician?

[Anonymous Coward]

I always have trouble trusting an elevator with no buttons on the inside, but I guess they are the way forward. There are a pile of them in the Auckland CBD in various buildings, most of the new refits seem to use them. Vero Tower, PricewaterhouseCoopers Building etc. I'm sure there are some in other cities, but most of our customers are in Auckland in the CBD.

Re:Mathematician?

[Anonymous Coward]

Elevator algorithms were pretty standard CS curriculum back when I was in college in the early 90's. This smells like another "Let's make women feel like they matter in technology by making a big deal out of something any halfway decent grad student can already do" type story.

Man I was with you until the second line. There's some latent woman-hate going on. What's the problem bro? Women turning you down too fast?

Same AC here. No, I've got no woman hate at all. Happily married for 25 years, in fact, so I haven't had anyone turning me down because I haven't been shopping around. Glad to see women in CS, just for the record- the best CS prof I ever had was a woman, she was quite frankly a wizard. It just bothers me when something becomes a big deal or news simply because a lady is the one doing it. It bothers me even more when pointing out that this is normal, run-of-the-mill CS work immediately garners accusations of "woman hate".

Anyhow, just to try and clarify what I was referring to: She's got a Master's, but the reporter keeps referring to her over and over as "Ms. Christie", when other pieces about men by this same writer just go with the familiar name or simply the last name. Maybe I was just feeling a little irritated when I posted it, maybe I was reading too much into the piece. It just seemed to me the report was trying to repeatedly slide subtle references to her gender into the story.

Re:Mathematician?

[stonecypher]

Isn't making the elevator go faster a job for an engineer?

It's a job for anyone who can do it safely.

For example, Southwest Airlines got a lot out of a psychologist in these regards, by reforming how they discussed lines, so that there was less jostling.

You don't shut jobs off from people who can do them for having the wrong title unless you're the Federal Government or a Silicon Valley VC.

Re:Mathematician?

[tbird81]

Thanks, I'll have to see if I can have a look on a day off.

Re:Mathematician?

[Anonymous Coward]

PWC building in the Auckland CBD has one.

Re:Mathematician?

[coolmoose25]

It is the Marriott Grand Marquis at Times Square. Saw a show on it (Nova I think) and was happy when I checked in and found the system I'd seen on TV. The elevator bank is a cylinder, people enter the inside, and there are elevators along the outside of the cylinder. Obviously there is a passageway to get to the inside of the cylinder, as if you are walking through the cylinder wall. There is a touch pad there where you enter your floor. It immediately tells you the letter of the elevator you're supposed to stand in front of. You walk around the circle until you reach that elevator, and in less than 5 seconds the doors open. About half a dozen people get on. The elevator has no buttons on the inside other than the help button... the elevator already knows where it's going. You stop at about 3 or 4 floors and you get off on your floor. I don't know what it does then - I'm guessing that in busy "up" times, it shoots to the ground floor and handles the next group. Going down works exactly the same way. There is often a longer wait for the elevator, but it only stops 3 or 4 times at most before whisking you to the lobby. All in all, a revolutionary system... that little bit of extra info makes all the difference.

OB: Doctor Strangelove

[Anonymous Coward]

It's all about Purity of essence!

MLT, fuckhead

[Hognoxious]

'faster' does not necessarily mean 'more frequently'.

It certainly doesn't when it's expressed in feet per second.

Or she could have gone with Executable UML...

[HellYeahAutomaton]

http://www.modelint.com/download.html

Executable UML The Models are the Code:
  Elevator Case Study
http://www.amazon.com/Executable-UML-A-Case-Study/dp/0970804407

Never never never...

[Ossifer]

... say "I feel like I get paid to play videogames." That basically says "please cut my salary by $30,000.00"...

Re:Never never never...

[hraponssi]

Or get replaced with a smartphone game, where the players do your job..

Future algorithm ...

[fahrbot-bot]

... when elevators can move in more than one plane: 10 PRINT CHR$ (205.5 + RND (1)); : GOTO 10

Re:Future algorithm ...

[girlintraining]

... when elevators can move in more than one plane: 10 PRINT CHR$ (205.5 + RND (1)); : GOTO 10

I tried using an elevator based on that once. It took me all over the place, and gave the appearance of doing so intelligently, but I never actually managed to arrive where I wanted to be. I eventually caved and shelled out the money for a proper Wonkavator; Haven't had a problem since, except for the occasional child disappearing while using it.

Re:Future algorithm ...

[fahrbot-bot]

... when elevators can move in more than one plane: 10 PRINT CHR$ (205.5 + RND (1)); : GOTO 10

I tried using an elevator based on that once. It took me all over the place, and gave the appearance of doing so intelligently, but I never actually managed to arrive where I wanted to be.

Yes. Many a day I used the stairs.

I eventually caved and shelled out the money for a proper Wonkavator; Haven't had a problem since, except for the occasional child disappearing while using it.

So there's an up-side.

P.S. Let me know when you finish your training, girl, and we'll talk... :-)

What?

[Anonymous Coward]

If she was optimizing and worth anything trying different initial conditions would be the smallest part of the whole operation. Developing the math models for the system and tightening the ranges that approximations are used over would the large part of the operation. I have no idea why it would seem like a video game unless the output is horribly verbose. I suspect the individual cherry picked to show the most fun parts of her work and not the soul sucking bureaucracy around it.

Improve the score!?

[loufoque]

What do you mean improve the score?
You mean the programmers aren't even capable of solving the problem of finding the best solution?

Even if it's NP-complete, it's not like there are so many elevators that you can't find the best solution in reasonable time.

Re:Improve the score!?

[Anonymous Coward]

Then do it.

Re:Improve the score!?

[loufoque]

Sure, I'm a consultant. You can hire me for the right price, no problem.

and her iPOD has

[cellocgw]

one certain Aerosmith song on it.

in the old days

[Anonymous Coward]

code was tested in N Y City, on the grounds that new yorkers are more impatient, so if they were happy.....

Otis? Hmmm...

[jimicus]

Rumour has it that Otis have (or at least had) a UK office in the town of Reading (for our American cousins, the town is pronounced "Redding").

Their receptionist answered the phone with "Hello, Otis Reading?"

Re:Otis? Hmmm...

[Anonymous Coward]

Siemens used to have an office in the UK town of Staines (yes, really! though it's no longer there) You can imagine how the receptionists answered the phones, "Hello, Siemens Staines"

Re:Otis? Hmmm...

[cellocgw]

Your American cousins say, "Thanks, but we really do know that. We've got Reading and North Reading here in MA. Now try figuring out how we pronounce Dorchester and Worcester."

Re:Otis? Hmmm...

[ShaunC]

The Reading Railroad existed in the mid-1800s and has been a fixture on the Monopoly game board since at least the 1930s. We don't pronounce everything differently on our respective sides of the pond. :)

Re:Otis? Hmmm...

[Anonymous Coward]

Despite what people from Massachusetts might think, the rest of the country does not find the way they pronounce things is normal nor intuitive. We do find it oddly adorable though, just like people from Jersey or a pug dog peeing on your floor (same thing, really).

So thank you to our UK cousins for letting us know.

Re:Otis? Hmmm...

[Anonymous Coward]

Now try figuring out how we pronounce Dorchester and Worcester."

That's wicked easy.

Re:Otis? Hmmm...

[Anonymous Coward]

I was in Redding, California reading about Reading.

Re:Otis? Hmmm...

[Anonymous Coward]

The recepionist at Schindler's has it even better: "Schindler's lifts"

Most needed optimization

[Richy_T]

Multiple forced door closings when people hold the door open to chat.

Second most needed optimization:

Give me an ETA so I know when I'd be better off taking the stairs.

Most annoying feature that needs to be removed (some elevators):

If you'd manually hold the door for someone (those door open buttons are hard to find in a hurry sometimes. I believe there's even a paper on it), the door would then close v_e_r_y s_l_o_w_l_y while beeping reproachfully at you. The last thing I need first thing in the morning is passive-aggressiveness from a machine.

Re:Most needed optimization

[dj245]

(those door open buttons are hard to find in a hurry sometimes. I believe there's even a paper on it)

In most of the elevators I have used in the US, they don't even work. I am really suspicious that they are even connected to anything and are just there as a placebo. Other countries don't seem to have a problem with this and the door close button closes the door.

Re:Most needed optimization

[Anonymous Coward]

Another one: conditional alert tone, depending the elevator is going up or down. At least here where I live , most elevators always play the same sound.

Re:Most needed optimization

[jrumney]

The door open button normally works (to a point - it may be ignored if the door is almost closed, or if you hold it too long), it's the door close buttons that are normally a placebo, or in best case they sometimes override the slow door close after the door was held open, to get the door to close at normal speed.

So why are elevators still so dumb?

[Anonymous Coward]

They have a built-in weight sensor, how come they don't know when they're full? At rush hour, elevators are always full and they still stop on every fucking floor because especially at rush hour, there are always people waiting outside. And of course nobody can get in and nobody wants to get out. That's hardly an optimization conundrum, it's sheer stupidity.

In the article she says the main goal is to minimize waiting time. But isn't the time you spend in the elevator also waiting time, and isn't that much less comfortable than waiting outside? So the primary goal should be to minimize the length of a ride, not to minimize pre-boarding waiting time. If the waiting time before the elevator arrives exceeds 20 seconds or (more realistically) 5 minutes and you're not disabled, you can still choose to take the stairs, which means you're doing something for your health and the others have a faster ride, win-win.

Re:So why are elevators still so dumb?

[BradleyUffner]

They have a built-in weight sensor, how come they don't know when they're full? At rush hour, elevators are always full and they still stop on every fucking floor because especially at rush hour, there are always people waiting outside. And of course nobody can get in and nobody wants to get out. That's hardly an optimization conundrum, it's sheer stupidity.

Just because the volume of the elevator is physically full of people doesn't mean that it's at it's maximum weight. Not every person weighs the same and takes up the same amount of floor space.

Re:So why are elevators still so dumb?

[TheLink]

Yes, but in many cases the elevator stops on every floor even if the elevator is already near the maximum weight- as you can tell by the warning buzzer going off intermittently.

AND for cases where the elevator is not near the maximum weight but effectively full for other reasons[1] the elevator can guess if:
1) the load is high enough
2) the load does not change after the doors open (nobody gets in or out).
3) the external button is pressed again after the doors closed (someone actually is there who wants an elevator)
And thus decide it is "effectively full" and not stop on future floors till the load decreases below a threshold.

It might be better for a 90% full elevator to prioritize serving its current load till say 50% full and leave the other floors to the less full elevators than for the 90% full elevator to stop on many floors taking one person and letting out one person. Stopping, opening and closing doors and restarting takes a lot of time. Not worth it for one person during peak times, might as well take the whole load where they want to go, then go back and get a full load again.

[1] The elevator may hold people who do not make room for others. Or holds an item that takes up extra floor space.

Future fortune ...

[Anonymous Coward]

An ELEVATOR PROGRAM written without the use of a LOOP, VARIABLES, and without very complicated SYNTAX.

It's called nudging in the trade...

[the_rajah]

You will most commonly find it in large urban areas like NY and Chicago. In the Midwest where I worked in the elevator business, it's rarely a requested feature because folks aren't in such a rush in general.

We actually use different speeds for...

[the_rajah]

single floor runs and for multi-floor runs. Yes, the faster the car is running, the longer the slowdown distance since smooth acceleration and deceleration are desirable.

In the elevator trade...

[the_rajah]

We rate elevator speeds in feet per minute. A typical small hydraulic elevator will run 100 FPM. A high-rise express car may get up to 1,500 FPM.

Re:In the elevator trade...

[inode_buddha]

Wow -- those kinds of speeds make me wonder about the air venting that must be required at the top and bottoms of the shafts. Thats amazing!

Yes but....

[guruevi]

Does it also simulate who farted?

I don't think

[DiSKiLLeR]

I don't think there's any intelligent code running the elevators in my building.

I live in a 14 floor apartment building. I frequently come home in the evenings to see both elevators just chilling idle on the 14th floor....

It makes me want tear my hair out.

The elevators in the high rises I work in don't seem to have these problems. The building I specificlaly work in most of the time has 6 elevators though so its less of an issue though.

Re:I don't think

[PCM2]

I don't think there's any intelligent code running the elevators in my building.

I live in a 14 floor apartment building. I frequently come home in the evenings to see both elevators just chilling idle on the 14th floor....

Does your building have any security? Maybe the policy is for the elevators to idle at the top floor after dark so that people coming in will have to hang around the lobby a certain amount of time before getting into the elevator?

Or maybe it's been determined that in a residential building, more people tend to be at home at nighttime than in during the day, which means that at night, residents are more likely to enter the elevator on a floor higher than the first floor, which means it's more efficient to have the elevator idle on a higher floor? And maybe they decided to make the idle floor the top floor because the people on the top floor are paying more rent?

I don't know how "intelligent" the elevators necessarily are, but it seems impossible that there's no kind of logic behind how they operate.

Single click lift

[Anonymous Coward]

In a busy building the best way to improve elevator capacity is to make people select the destination level before boarding. So instead of saying I want to use the lift I'll tell you where to later, the control system can optimise movements a lot better

Not all elevators have load weighting..

[the_rajah]

Those that do, are usually set at around 75% of rated capacity. When load weighting is activated, the car should ignore hall calls, but, obviously, cannot ignore car calls.

Re:Not all elevators have load weighting..

[Anonymous Coward]

Many years ago, I was on an elevator that obviously had load weighing. Not just the nudge buzzer for holding the doors open too long, but also rang the alarm bell twice as the doors opened at each floor trying to warn of overload. Thankfully it didn't get stuck or set the safeties, because no one left the elevator until the lobby floor.

There are still a lot of relay controllers in use.

[the_rajah]

Yes, pre-microprocessor, relay logic elevator controllers. I see lots of them that were put in 40+ years ago still working and doing their job after all these years.

Pressing both the down and up buttons

[Grieviant]

I'd like to hear her comments on people that press the up and down buttons when they simply want to go down. It irritates the hell out of me because I believe this practice increases the average travel time for people already on the elevator as well as the impatient double-button-pusher himself.

For example, say someone on floor 6 (who wants to go to the ground floor) presses both buttons and then gets on while the elevator is on its way up. The extra delay caused by the unnecessary stop at floor 6 means, statistically speaking, that people on floors 7 and up will have more time to summon the elevator before it reaches its highest floor and eventually descends to floor 6 again on its way to the bottom.

When the double-button-pusher issues their goofy "Oh, I'll just get on for the ride ... " comment, I frown menacingly and stare at them for the duration of the trip.

Re:Pressing both the down and up buttons

[Anonymous Coward]

This is standard behavior at Deloitte Tower in Port Moresby. The whole building is woefully underserved by 4 elevators. At rush hour, the only way to get an elevator is to find one going down to below-building parking and force it to open in the lobby. Fuck I hated POM.

Dissertation on elevator dispatching

[quannah]

I just read about someone who did his dissertation on elevator dispatching algorithms here. The full dissertation is here: Heuristics in dynamic scheduling: a practical framework with a case study in elevator dispatching.

"to do the greatest good for the most people"

[circletimessquare]

socialist scum

this otis elevator sounds like a communist company. whoever this otis was, he obviously was no real capitalist or real murican

a real murican elevator would have a real murican algorithm, and not an algorithm by this eurotrash muslim atheist Theresa Christy. a "mathematician?" obviously some liberal college major where they teach her women should be allowed out of the home

the real murican elevator algorithm would scan everyone's wallets, and only one guy, the guy with the greatest amount of cash in his pocket, would get to use all of the elevators for him personally, 99% of the time, even if he wasn't using the elevators and everyone else had to use the stairs

Re:"to do the greatest good for the most people"

[Anonymatt]

you are hilarious. the ladies must love you.

Re:"to do the greatest good for the most people"

[Anonymous Coward]

Those are no 'ladies'... if you get my drift.

Well, the ONLY diff. I see?

[Anonymous Coward]

Is that the resting place of the diskdrive head probably doesn't vary (like you describe for start of workday, lunch, & of course, quitting time - moving it to the most optimal spots during certain daily time periods).

Afaik? The HDD tends to try to keep the read-write heads in the CENTER of the disk (or rather, center of the filemass (moved to outermost fastest tracks with defraggers for fastest access/seek due to larger rotational diameters)).

You can't "move" the MFT$ (master file table) & certain other system files during usermode after all!

(At least NOT during usermode access to accomodate for times it *MIGHT* be different for differing work patterns (say you work @ home, & do your work the 1st 8 hours you wake up, & then the rest is family usage, your leisure, etc./et al)).

However, with NTFS & probably other modern filesystems?

MFT$ is placed in the MIDDLE of the "filemass" though for "optimality", since it's needed for file accesses of any kind (time of access stampings too, etc.) & then binary search patterns (like NTFS uses in b-tree seeks) do the rest!

I find this algorithm pretty amazing & VERY "common-sense", & that elevator algorithm & its variants, do one hell of a good job on QUEUEING UP REQUESTS, & then issuing them in the order the disk drive head passes over the areas concerned, in the most efficient order possible.

1 of its variants use 2 buffers (1 = currently being serviced requests, & 2 = upcoming requests to service): THIS seems like the smartest way to go about it imo @ least.

* Anyhow/anyways - I didn't think you were being a jerk, I hope you feel the same way regarding myself...

(Actually? I thought you offered some decent enough points, but you MUST ADMIT, the algorithms here are AMAZINGLY similar & I didn't SAY they were the "exact same" either)

Plus - I'd wager since the one for HDD's is named "Elevator Algorithm", the harddisk folks GOT THE IDEA from folks like this lady!

APK

P.S.=> Lastly - Sorry: Not "graduate level student"/postgrad/postdoc etc., in CSC!

I got the AAS 60 credit hours outta the way & went to work in the field as a programmer back in 1994 onwards!

(I've been "chipping away @ the stone" since then, & am 90/120 credit hours into the B.S. in CSC currently, taking coursework here and there as time & money permit)...

... apk

Good point - However...

[Anonymous Coward]

Already covered here -> http://hardware.slashdot.org/comments.pl?sid=3287917&cid=42156255 .

* In fact? I'd say the REVERSE of that which you have... how so??

I'd say the hard disk people used elevator folks' ideas though, especially considering the name of the algorithm employed.

APK

P.S.=> See the link, you'll understand...

... apk

Happy Vertical People Transporter

[Anonymous Coward]

99 comments so far and no mentioning of the predicting Happy Vertical People Transporters in The Hitchhikers' Guide to the Galaxy?

Slightly worrying lift

[rklrkl]

The lift (UK speak for elevator) I have at work is reasonably sensible - there's only 4 floors in the building, so it tends to keep one lift on the ground floor and one on the 4th floor when idle. However, I had a few fun things happen:

* All the lights went out in the lift as I was travelling in it, but it did get to the right floor and open the door.
* The computerised voice announced "floor five" one day, which is creepy when I got off at the top (4th) floor!
* The lift voice frequently says "please mind the doors" and then does nothing for 5 seconds before repeating the phrase again and only then begins closing the doors! Other times, it'll start closing the doors as soon you press the button and half-way through the closing it then pipes up "please mind the doors".
* I've had the alarm test for the building go while I've been in the lift and the voice announced "fireman has taken control of the lift and it's returning to the ground floor", which at least it duly did.

I think the only thing I would say is regularly unpleasant is that the lifts we have are quite small and I suspect several of our staff avoid them because of claustrophobia (it's easy to avoid them if there's only 4 floors of course).

Re:Slightly worrying lift

[Smerta]

Sounds to me like you're a beta tester.

What is wrong with me?

[Anonymous Coward]

I neglected to mention caching @ both or either the logical filesystem level, or block device level - this is an area that has a LOT of variation in it, more than hard disks read-write heads placement &/or movement related only, imo, & is an area that elevators *might* gain by especially if digitally controlled by programmable devices like PC's are.

Think about it

(Keeping in mind with remembering usage patterns & Sir_Sri noting time of day use patterns, but >b?also speeding up the pulleys' pace & thus, the elevator cart itself, between places that aren't used much or asking for service in that pass!)

However - I don't know how this'd go for "ergonomics" though - lol, "warp 15" between 2 or 3 levels down to turtle speed, MIGHT bash a few heads in (not good/cool, lol but that's an extreme example & exaggerating)...

Still - just a thought (patent pending, all rights reserved, etc./et al), lol! Probably already thought of, there is truly very little totally original thought imo.

APK

P.S.=> Anyhow/anyways - If that type of "caching's" not going on with elevators I'd be surprised though!

Not just for positional placements & physical read-write head movements, but optimization of paces used between floors occupied or demanding service, vs. unoccupied or not demanding service...

(Again - my 'warp speed' example down to 'turtle speed' is extreme exaggeration though since it would be physically detrimental, but it could be done for better overall performance & probably already is being done I'd guess)...

... apk

Re:What is wrong with me?

[swalve]

Meth kills.

Re:What is wrong with me?

[Meski]

If they could sense that they were empty, with 100% accuracy, you could drive them a lot faster when heading to a call. Hmm, free-fall lifts. Restaurant on top floor, that could be fun.

Re:What is wrong with me?

[Anonymous Coward]

Perhaps you ought to stop doing it then.

My retirement job

[russotto]

The elevators in my building are user-hostile. Door closing delays set so short that if the first person isn't fast, they'll close after the stream of people leave but before the first person enters. And while they won't actually cut you in half (that I know of), they will give you a bruise if you go in while they're closing. One elevator goes both up and down from the lobby but has no indicator for which way it's going. The annoying door beeper has no delay; it beeps whenever anyone is in the doorway. They frequently break down. All in all, exactly what you'd expect from NYC elevators.

Which brings me to my ideal retirement job. I'd love to maintain the software.... for escalators.

Noooooo!

[Culture20]

Elevator pseudocode is the heart of many a CS course. And CS courses were promised to be devoid of practical application.

Re:Noooooo!

[Anonymous Coward]

Elevator pseudocode is the heart of many a CS course. And CS courses were promised to be devoid of practical application.

Little known fact--if you are on a moving elevator and start to force the doors open, it will stop in between floors. Just don't try to get out when the elevator floor is high enough above a building floor that the shaft is exposed. How do I know? In the words of my roommate, I was shafted, literally -- fell into the shaft on the 14th and caught my self on the cables level with the 11th floor doors. My partner (in elevator hacking) quickly ran down the three flights of stairs, I was able to swing over, release the door catch and he opened the doors so I could swing out of the shaft...

As I was falling, my partner claims that he shouted "Nooooooo!", but I never heard him, I guess my reflexes were too busy getting a grip on the control cables?

Re:Noooooo!

[MrL0G1C]

I'm having difficulty believing that:

A) You're stupid enough to force open the doors whilst the lift is moving.

B) Also stupid enough to step forward when the lift is between floors.

C) Also stupid enough to fall through the gap.

D) There is a gap large enough to easily fall through.

Re:Noooooo!

[MrL0G1C]

Ooops, the most unbelievable bit is due to physics, you would not be able to catch on to anything after falling 3 floors, especially not a cable, Mr Indiana Jones.

Re:Noooooo!

[Anonymous Coward]

Ooops, the most unbelievable bit is due to physics, you would not be able to catch on to anything after falling 3 floors, especially not a cable, Mr Indiana Jones.

College students often do unbelievably stupid things. Elevator hacking was all the rage in 1973, and seemed pretty cool at the time. It's now obvious that leaving the elevator between floors was pretty rude, and inconvenienced a number of people--maybe that is what we were trying to accomplish(??) At any rate, my partner in this prank climbed out backwards, on his belly, feet first. When I tried the same thing I slipped, swung around the edge of the car and fell into the shaft, with the hanging control cables in front of me. Catching myself on the cables took most of the skin off both hands. I was skilled at rope climbing and managed to hang on with hands and feet, avoiding a 12 floor drop (including basement).

A few years ago, I met another guy with a related story. In his case it was in the 1940's and the manual elevator either had no safety or it had been defeated. At any rate, the elevator wasn't at the floor when he tried to step in, and he fell from ground floor into the basement and took most of the skin off his back (against the edge of the floor). We were both able to have a good laugh about being shafted.

Re:Noooooo!

[Anonymous Coward]

If I've done my math right, you'd be falling at ~15.2 m/s or ~34 mph 3 floors down. Disregarding aerodynamics.

Re:Noooooo!

[Anonymous Coward]

If I've done my math right, you'd be falling at ~15.2 m/s or ~34 mph 3 floors down. Disregarding aerodynamics.

Much less free fall than that -- I did stop 3 floors down, so must have bumped into the cables almost immediately. Most of the drop must have been spent trying to get a grip with hands and feet/legs. The cables were greasy, there was black grease on the front of my clothing and deep in the wounds on my hands. As noted earlier, I was skilled at rope climbing and those reflexes must have kicked in--the actual time of falling is not in my memory. Memories of the time just before, and then hanging in the elevator shaft are vivid.

Efficiency may include power consumption

[Fencepost]

Another constraint that she may be considering is power efficiency - there may be tradeoffs between minimal wait time, etc. and power consumption, and the electricity cost for lifting an elevator car many times a day is not going to be negligible.

Firmware upgrade?

[FRiC]

They need to release some kind of upgrade for existing elevators. At my office building of 35 floors with Otis elevators. When an elevator is already stopped at a certain floor. Instead of opening the door immediately when you press a button, the elevator leaves immediately and you need to wait forever for another elevator to arrive since the other elevators think you've already left. The solution is then to press both up and down buttons, irritating the hell out of every one in the building.

All of which money is wasted

[Anonymous Coward]

The key to elevator optimization isn't in the elevator, itself, due to the sporadic and often irregularly clustered usage of business elevators. It's in the elevator button: an elevator button replaced with a keypad that allows *selection of the floor to go to* allows far more efficient scheduling of elevators and stops than trying to optimize based on plain service requests and key presses after people are *already in the badly scheduled elevator!!!*.

This works extremely well in extremely tall buildings such as those recently erected in Dubai, and with the dropping prices of touchpads and keypads with controllers, it's much more efficient than wasting time and lab space on a fundamentally insoluble attempt to outguess erratic human behavior with deliberately missing information. Investing in complex algorithms and research is like trying to restore the analog sound quality to something you've digitally sampled once a second: you can invent powerful algorithms that are utterly useless for real sounds, but you're better off sampling more of the original data and responding to *that*.

Ask Slashdot?

[Anonymous Coward]

I think she'd be a great interview for Ask Slashdot. I'd like to know more about the mathematics behind designing elevators.

repeatedly pushing the button

[RandySC]

I like to think that when the elevator doesn't show signs of coming to my floor, and I repeatedly push the button, that someone on a different floor and moving too slowly is caught in the doors :)

I love when I see third world people push the down button when they want to go up!

Remember PROBE?

[FearTheFez]

I wonder if she has ever had to deal with people using her elevators to kill people? And does it call her Mom? https://www.youtube.com/watch?v=UKBKjepmsOE

Guaranteed they get an elevator with up and down

[Anonymous Coward]

What if the elevators are not being used?

Don't disregard the fact that some elevator systems use parking floors. If I know that the 3-elevator bank has one park on 1, one park on 3, and one park on 5 when not in use... well, I might just hit up and down if I'm on floor 4.

What's going to happen? Now I have a two out of three chance of getting an elevator quickly. Either the one on 5 is going to come down to 4, or the one on 3 is going to come up to 4. What if both come to four--now, I have my choice of two elevators. Or, if only one comes to 4 because it can either go up or down, I still got my elevator. Doubtful that the one parked on 1 is going to go all the way to 4, so it will be a shorter wait.

(Going for the ride isn't a big deal, I still have to deal with the elevator calls going up or going down to other floors, for example if I ultimately want to go down to 1. But it still beats waiting in the elevator lobby, that's for sure.)

This isn't elevator pranking nor elevator hacking, because that's just how the system works out when elevators stop on parking floors when not in use.

Two-storey elevator car doubles capacity

[Anonymous Coward]

* Saw this a year or two ago -- a two-storey elevator car:
        o Double the carrying capacity
        o Stops at adjacent floors, e.g in the Empire State Building, would open its two sets of doors at floors 1 and 2. Close all doors, haul up to observation deck floor and , open doors.
                    + In this scenario, everyone has to walk one flight of stairs: Either at the bottom or at the top when going up, and likewise when going down.
* Heck, even a triple-storey elevator car could make sense at the ESB where there is no optimization to do. One shaft, 3x the capacity.
* Again, not my idea, but not Otis' either.

Sirius Cybernetics Corp. People Transporters?

[Anonymous Coward]

Think Douglas Adams gets prior art dibs on this one:

From the Hitchhiker's Guide:

Modern elevators are strange and complex entities. The ancient electric winch and “maximum-capacity-eight-persons" jobs bear as much relation to a Sirius Cybernetics Corporation Happy Vertical People Transporter as a packet of mixed nuts does to the entire west wing of the Sirian State Mental Hospital.

This is because they operate on the curious principle of “defocused temporal perception.” In other words they have the capacity to see dimly into the immediate future, which enables the elevator to be on the right floor to pick you up even before you knew you wanted it, thus eliminating all the tedious chatting, relaxing and making friends that people were previously forced to do while waiting for elevators.

Not unnaturally, many elevators imbued with intelligence and precognition became terribly frustrated with the mindless business of going up and down, up and down, experimented briefly with the notion of going sideways, as a sort of existential protest, demanded participation in the decision-making process and finally took to squatting in basements sulking.

average american is 22 pounds heavier....

[Anonymous Coward]

average american is 22 pounds heavier....

Thats the line that got me thinking... How much is that costing the US in fuel costs alone...

Elevator algorithm ~ hard drive algorithm

[Anonymous Coward]

Think she also works for Seagate? Elevators aren't the only devices that use elevator algorithms.

Semi-smart

[Anonymous Coward]

The building I work in has three elevators. In the morning all empty elevators will go down to the lobby to wait for people. But in the afternoon it's different, each elevator has a preferred floor to wait on while empty. The building has ten floors, when all elevators are empty there will be one at 8, one at 5 and one at 3. Not always the same elevator at the same floor, either, there must be something smart(ish) going on.

Works pretty good, except when you are trying to get from 10 to ground floor during the morning rush.

She should look at my jobs elevators

[Chewbacon]

They're made by Otis and their decision making is horrible. I'm on the third floor and I've seen the car come from the basement when there's two closer to me. On occasion there's one on the same floor!

Re:She should look at my jobs elevators

[Anonymous Coward]

The customer skimped on the dispatch controller. Happens frequently. Friggin' cheapskates.

Re:She should look at my jobs elevators

[gef7]

Indeed, I have seen some very questionable behavior with OTIS elevators, too. As an engineer, I think there is some juice to report here!

Air trapped in elevator shafts

[Anonymous Coward]

I used to work in a building that had a 9 story elevator and when you waited for it to come up to the 9th floor you could hear air being slowly forced out of the closed doors and I often wondered how much energy was being wasted trying to displace that air in the shaft. It could really add up over time. I winderif the elevtor companies ever think about this.

Elevator algorithms work for drive heads

[boddhisatva]

It's the same concept. If drive manufacturers add more actuators, the algorithms need to change. Unless you make a lot of assumptions, a read is queued and the thread blocks. Meanwhile the next task queues a read. Unless you are doing priority queueing and probably even then, you have no idea where the sector needed for the next read is. No point in defragmenting the disk unless it's some single threaded, single user system. So you do the reads in an order that is most efficient for the passengers (tasks) and the elevator (performance, energy efficiency, etc).

getting-it-up-is-only-half-the-battle

[Anonymous Coward]

what is this suppose to mean, timothy? does it have anything to do with the female-ness of the person in the article? if so, shame on you. if not, don't you think it could be offensive regardless?

think about it - getting it up is only half the battle. getting it up? you mean getting a hard-on, right? and you know the article is talking about a Woman, right? you know, female, hard-on. is this making any sense?

why did nobody else bring this up?

one of the EXTREMELY few articles on slashdot about a female and her skills and the fucking admin has the gall to post some kind of boner joke.

fuck me, right?

Re:Guaranteed they get an elevator with up and dow

[Neil Boekend]

Why would an elevator in this situation not come down from 5 to 4 if you want to go up? In "park" the software should select the closest elevator, in the absolute sense.
The directional info from the buttons should only be used when the elevator is in use and it matters whether the elevator is going up or down. If, in that case, you call an elevator and don't get in this results in a useless extra delay for those in the elevator.

Weight'd be key here then... apk

[Anonymous Coward]

Use scales then - the weight of the elevator cart itself's known. Any difference would indicate NON-EMPTY states.

* This'd be PRETTY CRITICAL though, & have to have redundancy or safety switches if the scale goes down... for health reasons!

APK

P.S.=> The ONLY PROBLEM, again, would be one of ergonomics (but not in a truly empty cart - however, what IF the scale malfunctions? Then your "rocket-ride" you describe, as I did with my 'warp 15 down to turtle speed' *might* happen... & might not be pretty!)...

... apk