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Newbie Furnituremaker needs help with actuating mechanisms

Discussion in 'Robotics & Mechatronics' started by skegemog, Aug 6, 2012.

  1. skegemog

    skegemog New Member

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  2. skegemog

    skegemog New Member

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  3. skegemog

    skegemog New Member

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  4. dave

    Dave New Member

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  5. skegemog

    skegemog New Member

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    Its true that the SPDT switch is momentary contact but it is an auxiliary to the RF switch. I don't think that the relays are latching as one needs to maintain contact with the SPDT swicth for the lift to move in either direction. When using the RF switch, momentary contact with the transmitter button will activate the lift to travel its full range. Also, with the RF switch it takes two contacts in the opposite direction to start movement in the opposite direction. I'm guessing the first contact releases the relay in the current direction and the second engages the relay in the new direction.
     
  6. skegemog

    skegemog New Member

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  7. skegemog

    skegemog New Member

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    the power supply plugs into one of these jacks, don't know what the other is for but I was able to pull 30 VDC off of it
     
  8. skegemog

    skegemog New Member

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    the three pin connector goes to the momentary contact SPDT aux switch
     
  9. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Could be. Or perhaps it's a safety feature to prevent an accidental single press from actuating the mechanism?
     
  10. skegemog

    skegemog New Member

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    if the lift is stationary and the rf switch is pressed in say the up direction, a relay audibly engages and the lift starts moving. if the down button is pressed a relay audibly clicks (disengaging?) and the lift stops. when the down button is pressed again a relay engages and the lift starts moving down
     
  11. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Understood. That would make a practical 'emergency stop'.
     
  12. skegemog

    skegemog New Member

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    that makes sense. do you think it is feasible to go beyond the diagram I drew and actually piggyback the relays for the panel off of the lift relays?
     
  13. alec_t

    alec_t Well-Known Member Most Helpful Member

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    Piggyback :confused: Do you mean physically mount them on top? Do you have any particular relays in mind? Spec?
     
  14. skegemog

    skegemog New Member

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    I don't have a spec, but going back to my original question I am trying to operate both mechanisms with the rf switch. So if the diagram i made will work and I could connect the switching input to the relays in the controller to appropriate relays that control the panel then theoretically, at least, i could achieve my goal
     
  15. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    Am I correct, that one mechanism has to operate the other?

    e.g. (OPEN)
    Door #1 is asked to open
    Door #1 opens
    Once door #1, activates switch Sc, door #2 is commanded to open.
    Door #2 stops on it's own when it reaches a limit.
    Door #1 stops on it's own when it reaches a limit

    e.g. (CLOSE)
    System is asked to close
    Door #2 starts to close.
    Once door #2 releases switch Sx, then door #1 is asked to close
    Door #1 and Door #2 stop at their own limits.

    There are other conditions here that aren't addressed. The "simplest" way to address them is disable open or close if any actuator is moving.

    The Switch Sx is a switch that is activated at the first opportunity door #2 is allowed to open and therefore is de-activated at the first opportunity that Door #1 is allowed to close. Limits excluded.

    Thus the logic could be broken down as follows:

    1. Lock out the remote and manual switches if moving.
    2. On rising edge of Sx activate OPEN on door #2
    3. On falling edge of Sx activate CLOSE on door #1

    If this LOGIC will work, there may be a way to accommodate stopping and starting in mid-stream.

    Note: I did not cover how to detect a Rising or Falling Edge or generating the OPEN or CLOSE. I just want to get the logic right. The output from the IR detector could be turned off when needed too.
     
    Last edited: Aug 20, 2012
  16. skegemog

    skegemog New Member

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    this is essentially correct
     
  17. skegemog

    skegemog New Member

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    this sounds correct to me, not sure what the "edge" refers to but I'm guessing some kind of threshold to compel another action...
     
  18. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    OK, there is EDGE and LEVEL detection and for now, let's talk about LOGIC.

    In a LOGIC system an INPUT is PULLED-UP to the LOGIC voltage and TYPICALLY a switch goes to ground.
    So, suppose, you had 1K resistor connected to +5 and a switch to ground.
    This now gives you two states, a logic 1 (when at +5) and a logic 0 when at 0 (the switch closed)

    (This is simplified for now)

    A RISING EDGE is the instant the voltage on the input changes from 0 to +5
    A FALLING EDGE is the instant the voltage on the input changes from +5 to zero.

    Now suppose, you were given a BLACK BOX that did the following:
    On a RISING EDGE of it's input (Sx), a 1 second contact closure was provided for OUTPUT A
    On a FALLING EDGE of it's input (Sx) , a 1 second contact closure was provided for OUTPUT B
    A third output would be the state of switch Sx
    A fourth output would be the inverted state of Sx

    Let's suppose you were also given a black box, that told you:
    MOTOR A is MOVING
    MOTOR B is MOVING
    (LOGIC combinations of the two inputs are optionally available too such as:
    1. Neither motor is moving
    2. One of the motors are moving
    etc.

    Now for the LIMITS, you might have to provide two of them. One for the motor and one for the LOGIC.
    Things such as reflective object sensors or slot sensors, switches and hall effected switches are part of your arsenal.

    What could you do with this?
    See, how you could work with such a black box.

    Although possible, the switch Sx could be a blip or be continuous from a slotted sensor. Only you can decide this. The LOGIC might be easier if it wasn't a BLIP.
     
    Last edited: Aug 20, 2012
  19. 4pyros

    4pyros Well-Known Member Most Helpful Member

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    Sounds like the only way to stop it before a limit switch. Say if you only wanted it half way open or closed.
     
  20. alec_t

    alec_t Well-Known Member Most Helpful Member

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    For when you're only half watching TV and have your mind on other things? ;)
     
  21. KeepItSimpleStupid

    KeepItSimpleStupid Well-Known Member Most Helpful Member

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    I think what the OP was trying to say is"

    PUSH while moving - STOP & set the next direction state to CLOSE; Present State Stopped
    PUSH when stopped - Move in next direction state; PRESENT STATE Moving
    If OPEN limit - STOP; Force NEXT STATE to CLOSE; PRESENT STATE OPENED
    If CLOSED limit - STOP; Force NEXT STATE to OPEN; PRESENT STATE CLOSED

    It's just harder to deal with when there is 2 actuators, but if you allow the operation to complete it's easier. You can disable the IR when moving by "MUTING" the IR signal from the detector or turning the IR detector off. The detector should only have 3 leads. +5, Ground and signal.
     

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