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How to stop a motor from running when it is physically stopped

Discussion in 'Sensors and Actuators' started by toms9248, Oct 16, 2015.

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  1. toms9248

    toms9248

    2
    0
    Oct 16, 2015
    HI,

    If I needed to stop a motor from running and stay still when it is physically stopped, how would I do that. As far as i am aware the motor under these conditions would start to draw a higher current so at this point the motor would need to hold steady and not move.

    Thanks in adavnce:)
     
  2. Martaine2005

    Martaine2005

    2,716
    734
    May 12, 2015
    Hello, yes, stalling a motor would draw large amount of current. Not really recommended.
    But it would all depend on the motor and size.
    You may want to look at motors with an electronic brake.

    Martin
     
  3. Alec_t

    Alec_t

    2,819
    754
    Jul 7, 2015
    Some form of brake will be necessary unless the motor is driving its load via a high-ratio reduction gearing which has lots of friction, e.g. a worm-drive.
     
  4. Minder

    Minder

    2,953
    623
    Apr 24, 2015
    You don't mention the type of motor, e.g. a DC motor will be braked by placing a short circuit across the terminals when stopped, this would need to be interlocked with the power supply to prevent both conditions at once of course.
    A stepper motor also has maximum torque at zero rpm, and can be fed steady DC at this point to hold in position.
    M.
     
  5. Tha fios agaibh

    Tha fios agaibh

    2,095
    702
    Aug 11, 2014
    There may be a mechanical solution as well as an electrical solution. Tell us more about the application.
     
  6. davenn

    davenn Moderator

    13,577
    1,866
    Sep 5, 2009
    the standard solution is a limit switch

    tell us more about how the motor is being used so we can see if that solution is applicable


    Dave
     
  7. toms9248

    toms9248

    2
    0
    Oct 16, 2015
    So the project is A-Level coursework. I am designing an IR sensor electronic bin a bit like this one:

    http://www.argos.co.uk/static/Product/partNumber/2489131.html

    I won't be producing the full product, just bread boarding the electronic innards.

    I need the 'lid' to stop moving when it encounters resistance such as being fully open, closed or a hand/object stopping it while it moves. If the best way is, for example, with a mechanical brake on the lid then I would just need to show the component that would be used to move.

    The project would run on approx 9V DC and shouldn't theoretically take up loads of space (if actually produced). I can use almost any component within reason.
     
  8. Steve Peart

    Steve Peart

    51
    3
    Sep 16, 2015
    For this project, I wouldn't use a regular motor and consequently, the need to detect stalls. You would be better off using a stepper motor or a servo that does a 90 degree rotation capable of moving the weight of your lid. This would simplify the circuit substantially and you wouldn't have to detect anything about stalls, just provide the proper voltage to a servo for open and close, and you're set.

    If you absolutely HAVE to use a regular motor, make it so the max height of the lid being open, connects a circuit that will short out the motor and make it stop turning. Then you aren't detecting anything electrically, just clipping the circuit at the maximum lid angle.
     
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