Ups and Downs of elevators

Discussion in 'General Electronics Chat' started by KL7AJ, Jan 15, 2009.

  1. KL7AJ

    Thread Starter AAC Fanatic!

    Nov 4, 2008
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    Some people are bound to ask "What's with all this obsession with elevator control circuits anyway?"

    Elevator control is one of the classic (and oldest) problems of servo and feedback systems...and actually skirts on the topic of artificial intelligence.

    They first started thinking analyitically about this when building the Empire State Building....and the IDEAL solution still is not at hand.

    There are a lot of aspects of this problem. WHO gets first dibs? First come first served may SEEM simple enough. However, it can be REALLY inefficient in energy, wear and tear, etc. Is it always most efficient to make a "milk run"...the elevator always moving in the same direction as far as possible?

    It's one thing if all the INPUTS are addressed before the "route." But how about AFTER the "route" is started? What is the most equitable method to allow "interrupts?"

    There's a lot more to this than meets the eye...which is why elevator problems will not go away soon...if ever.


    Eric
     
  2. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    Things start to change radically when two are available instead of a single one making possible a smarter use of them.

    Things tend to complicate when you need more than two.

    I always was fascinated with the idea of programming the whole thing with three or four cars but as a hobbyist project would be too much, I think.
     
    Last edited: Jan 15, 2009
  3. KL7AJ

    Thread Starter AAC Fanatic!

    Nov 4, 2008
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    There was kind of a landmark study done about 15 years ago on traffic flow theory. Scientific American did a big story on it. It was an answer to the question: "How come when they widen freeways it never seems to reduce traffic." The answer was startling on two levels. Number one: this perception was not imaginary. It was conclusively shown that widening freeways in the normal manner actually reduces traffic throughput.
    Number two: If vehicles were prohibited from EVER changing lanes....widening a freeway would help. This is laminar flow theory....identical in every way to fluid viscosity! As soon as vehicles are allowed to change lanes (turbulence) the size of the "pipe" becomes almost irrelevant.

    And yet, we still build roads the same way.

    Sad.

    eric
     
  4. atferrari

    AAC Fanatic!

    Jan 6, 2004
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    Sorry Eric,

    I will dare to digress even farther:

    let's say there is a road of four lanes with maximum speeds progressively higher, say 40, 60, 90 and 130 Km/h with all drivers in each lane running at their respective maximum. Any driver from the left could not drive in zig zag, whatever he tries for that.

    But if in any of two lanes (any I say) their drivers run at the same speed or those on the left slower than anyone on the right, the driver starting from the left has an enormous chance of being able to drive in zig zag.

    All this conditioned to the use of realistic speeds for common cars.

    Depending where you live and how people behaves there, you may not see this in real life. I was in the past, many times, the guy starting from the left. Thanks God I am refrainig myself from all that at present.
     
  5. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    Back to your elevator problem...

    Engineering and science can improve efficiency, but people still complain about slow elevators. A study showed that putting mirrors in the waiting area reduced the perception that the elevators were slow. People like watching people. I can't remember the reference, but it was a long time ago (>20 years). However, have you ever wondered why there are so many mirrors in elevator waiting areas? It's not like you need to get dressed when you get off, at least not usually.

    John
     
  6. eblc1388

    Senior Member

    Nov 28, 2008
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    "If elevator weight overload operated and reset while stationary in a route of moving down, do not stop on subsequent floors but go straight to ground floor"

    How difficult is that?

    Failing to do so would be a packed elevator stopping on many floors for nothing, except causing more frustrations to both the passengers waiting and those already inside the carriage.
     
  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    1) Not everyone on an elevator wants to get off at the same place or ground floor.
    2) What if the most popular floor to exit is not ground at certain times of day, e.g., lunch. So time is a variable.
    3) What if there is some other variable, like a flood warning?

    Bring back human elevator operators.

    John
     
  8. RiJoRI

    Well-Known Member

    Aug 15, 2007
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    There is already a mono-directional personnel carrier in use, which works fairly efficiently. Actually, there are TWO of them: Buses and railroads, both of which have schedules. Perhaps the elevator needs to be redesigned. Perhaps bicycle-like chains with fingers to hold the elevator cars, with one set always rising, the other always descending. A pusher at the top and bottom to move the cars from the up-shaft to the down-shaft. The cars would move from floor to floor, pausing for a fixed amount of time at each floor. Holding the door for more than a certain time would cause an alarm to go off. The period that the cars would be stopped would be long enough to move a car from the U-shaft to the down-shaft.

    In addition to the "local" elevators, there could be "express"elevators, skipping several floors between stops, thereby saving the "floor-stop" time for the floors missed.

    --Rich
     
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