Elevator tracking/sensoring

    Jul 11 2006 | 9:01 am
    Hi list,
    Id like to track the motion of an elevator within a building for a sound-art installation. Has anybody ever done this ? What kind of device could i use for that ? Accelerometers ? Are there wireless ones on the market ?
    Id be thankful for any ideas on this....
    cheers. m

    • Jul 11 2006 | 11:56 am
    • Jul 11 2006 | 12:49 pm
      last autumn i tracked an elevator's motion using an accelerometer mounted on the top of the ceiling. it wasn't wireless, but i had connected a mac mini up there to control some lights using a usb-serial adapter and a PIC. depending on your comfort level with electronics, you could roll yourown wireless solution (rf, wifi, bluetooth if the distance from the machine is'nt too great).
      while the results were (somewhat) stable, the elevator suffered from a fair amount of jiggle and that tended to throw things off since I was attempting to track which floor people were on. also, the elevator's timing was a bit inconsistent from floor to floor. we didn't have much time to set it up in there so that added to the general chaos in the space.
      another idea we tossed about, though i don't know if it would apply to your situation (certainly didn't to ours), was to install a camera in the elevator, pointing at some sort of visual cue in the elevator that displayed the floor number (a big lcd, one of those arrows with light up floor numbers, etc) and use some image processing to identify the floor.
      the best way, if the building has it, and you're allowed, is to tap into the building's security system and use that to monitor what floor the elevator is on.
      good luck, and i'd love to hear what solution you come up with!
    • Jul 11 2006 | 1:18 pm
      How about sonar? That's what all the robotics people use these days (polaroid kits)
      I've done measurements using sonar in the past, and it was precise enough, at least down to 10 cm or something (this is from memory, so I could be wrong though)
      Most elevator shafts have enough space in the bottom to mount a sensor system like this.
      I could also imagine a system of a wire wound on a spool with an encoder sensing how many turns of the spool in either direction.
    • Jul 12 2006 | 2:10 am
      I did some pretty coarse elevator tracking by sticking a contact mic on the motor. That might be another place to look. Be careful, in the US, the elevator inspectors don't like it when you get too close to the equipment.
    • Jul 12 2006 | 2:46 am
      Hmmm... I was going to suggest trying to piggyback on the elevator system's own motion indicators (often showing current floor position as well as up/down directional signals), but the problem with the elevator inspectors would probably put the kibosh on that idea.
      Eric Honour
      ------------------- Associate Professor of Music Composition and Music Technology Central Missouri State University
    • Jul 12 2006 | 2:32 pm
      Might be a job for RFID. For example:
      Mount the RFID chips on the shaft, mount the antenna on the elevator. Chips trigger as the antenna goes by.
      -- Paul
      -- ----- |(*,+,#,=)(#,=,*,+)(=,#,+,*)(+,*,=,#)| -----
    • Jul 12 2006 | 3:30 pm
      wonder if a gps receiver could possibly be employed?