Naked Science Forum
Non Life Sciences => Technology => Topic started by: deborah on 20/12/2016 09:49:44
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deborah asked the Naked Scientists:
Although we read In the US left to right and top to bottom,the buttons for floors on elevators are not set up this way. I work in a hospital where some elevators aren't even the same as others. None of them read in a way that makes sense. No one I've asked can figure it out.
What do you think?
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My hospital is even worse. Some idiot made the ground floor "Level 2" and the basement "Level 1".
As a result, visitors pile into the lift to go one floor up to "level 3" and lots of hapless departing visitors accidentally go via the basement to get out when they try to leave.
The excess energy spend in the hospital must be huge as a result. It's also encouraging people to be lazy...
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Most elevators I have seen would have the lower floor button at the bottom and the upper floor buttons at the top, which I've always assumed was just to be consistent with the order of the floors. Just as the "up" button in the lobby is generally above the "down" button, rather than in alphabetical order... We have a ground floor that is "level 1" and even that stumps people. You can watch visitors hover their finger over the "1" for several seconds before they finally come to the conclusion that there is no other possibility.
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We have a ground floor that is "level 1"
I recall that there is often a difference in practice between US & UK - the UK tends to mark the ground floor with a "G", and Floor 1 is above that. The US tends to mark the ground floor with a "1", with floor 2 above that.
lower floor button at the bottom and the upper floor buttons at the top
This has a nice parallel to the physical layout. But it fails in tall buildings, where the buttons would stretch from floor to ceiling, making it a bit hard to press them! So they have to be "folded" in some way to fit into a convenient height range for an adult, from hip to shoulder. And there are many different ways you could fold them.
None of them read in a way that makes sense.
One building where I work has removed all buttons from the inside of the lifts. It really confuses people when they walk into the lift, and don't see any buttons!
They have mounted several small touch-screens around the elevators - you indicate which floor you want, and it tells you which lift to enter. This eliminates the buttons inside the lifts.
They also economize space on the touch-screen, because it initially only indicates publicly-accessible floors with a reception desk. When you wave your ID card, it then displays the floors to which you have access.
Because these are both fairly short lists, there is no need to "fold" the layout on the display (at least in my case; I imagine the maintenance guy would have a fairly cramped layout on the touch screen...).
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We seem to have both the "1" and the "G" system in Australia. We also seem to spell some words the UK way and others the US way, so maybe we are just a little confused.
I think it would be fun to have a linear panel of buttons. People could get their exercise by jumping up to reach the buttons.
Out of curiosity, how does the touch screen work for the visually impaired?
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I work in a building where the lift buttons are marked
1
0
and
-1
However the floors have signs labelling them as G, 1 and 2
But the rooms on those flors have room numbers that relate to the floor you are on as
0,
1,
and
2
I use the stairs...
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I think it would be fun to have a linear panel of buttons. People could get their exercise by jumping up to reach the buttons.
... with the button for the nearest floor being the hardest to reach...
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... with the button for the nearest floor being the hardest to reach...
It's evil and wonderful.
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I think it would be fun to have a linear panel of buttons. People could get their exercise by jumping up to reach the buttons.
... with the button for the nearest floor being the hardest to reach...
OK, I'm lazy. So, if I get in the lift on the first floor and want to go to the second, all I have to do is press the button for the top floor, wait till the lift gets there then press the button for the 2nd floor.
No problem.
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Out of curiosity, how does the touch screen work for the visually impaired?
Good point! I haven't seen any visually impaired people trying to use the system.
When the new lift control system was installed, it displayed a rather weird behavior.
- Normal lifts stop at a floor, and engage the brakes until the doors close. Works well.
- With this new system, the lift would go up or down by a few cm in the couple of seconds after people got in or out of the lift. If the timing of people entering or leaving the lift hit a resonance in the control loop, the lift floor could go up or down by 10cm while people were entering or leaving; there were quite a few trips of the undesired kind.
- I speculate that they were using their knowledge of how many people had been assigned to that lift to count the people entering the lift(?). Unfortunately, trying to control the floor alignment of a lift to within 1cm at the end of 50 floors of steel cable is a tricky control problem. They have now reverted to a more conventional arrangement where the lift floor remains locked while people get in and out.
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- With this new system, the lift would go up or down by a few cm in the couple of seconds after people got in or out of the lift. If the timing of people entering or leaving the lift hit a resonance in the control loop, the lift floor could go up or down by 10cm while people were entering or leaving; there were quite a few trips of the undesired kind.
That sounds terrifying! So, given that the door is now 10cm higher than the ceiling, you would then be staring at the inside of the lift shaft, AND getting out of a moving lift? Hmm...I'm going to take those stairs...
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I think it would be fun to have a linear panel of buttons. People could get their exercise by jumping up to reach the buttons.
... with the button for the nearest floor being the hardest to reach...
OK, I'm lazy. So, if I get in the lift on the first floor and want to go to the second, all I have to do is press the button for the top floor, wait till the lift gets there then press the button for the 2nd floor.
No problem.
Trust you to think of the way around it... ;)
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Most lifts use a brake on the motor itself, not the car in the shaft. This requires the car to have speed steps ( or variable speed drives) on approaching a landing, to slow it down so it can stop with essentially a constant stress on the cables. On higher buildings I can see the benefit of active levelling though, as the long cable stretch will change with load, and the car will be designed as light as possible to increase capacity and also save on cable mass. Would need some damping to stop it oscillating, and that is likely what happened here, they got the time constants of the PID wrong, and had to adjust it down a lot, or just accept the car floor slowly changing level with the people going in and out. Cables likely are too stretchy, but with 50 floors you have to make a compromise unless you use tapered cables like mines do, where they go a kilometer of more down in a single stage.
A standard elevator is designed so a single cable can fail in use totally, with the car at double it's rated load, and it will still stop safely. Every 5 years our elevator techs come around with 2 tons of mass, to do the double load test, and it still has to start and stop within the level allowances. Emergency brake testing does require them to bring a crowbar and a big file with, to get the brakes off afterwards, and to remove the grip marks it leaves in the guide rails.