Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Motion control for a rotating a cylinder

  1. Dec 10, 2009 #1
    Hi, I am an inventor with mechanical expertise but I am a novice with electrical controls. I want to control the rotation of a horizontal cylinder so it rotates 360 degrees, returning to the same start/stop position each cycle. The cylinder is being driven by a 1hp 110v electric motor, at a rate of one revolution every 124+- seconds. The solution should also include a means to program 1 to 6 start/stop times on a 24 hour basis. I imagine some sort of angle position sensor is available. I would appreciate any thoughts.

  2. jcsd
  3. Dec 10, 2009 #2


    User Avatar
    Science Advisor
    Gold Member

    Welcome to PF Whynotreuse.
    I am assuming you are using some gear reduction between the motor and cylinder? I would think the momentum of a 1hp motor would make it difficult to get it to stop right at 360 degrees. How accurate do you need to be?
  4. Dec 10, 2009 #3
    Thank's for your reply.
    It has to be very accurate. I was thinking the momentum would be relatively constant (6o:1) reduction ratio. Therefore my thoughts would be an adjustible sensor which stops the cycle perhaps a degree or two before 360 degrees. This should allow for the (X) degrees of movement from momentum. The cylinder is driven by sprocket and chain with a tension device removing the slack. More data available should you need it.
  5. Dec 10, 2009 #4
    You could put a retro-reflector and a photo-detector on the outside of the cylinder, or a small hole in the cylinder with a light behind it, or a micro-switch, to stop rotation every 360 degrees. After a pause, you could have a timer that starts the motor again. You could get very accurate positioning if you used a dc motor rather than induction, but they are more expensive.

    I have (in my hand) an isolated single phase solid state switch that is rated at 120 V, 25A that I paid ~$10 for about a year ago. I don't know how good it is for inductive loads.
    Bob S
    Last edited: Dec 10, 2009
  6. Dec 10, 2009 #5
    Very helpful. I like the idea of a micro-switch since this device operates under harsh conditions and a photo sensor may get dirty. Any idea who supplies the kit necessary to get this done?


  7. Dec 10, 2009 #6
    Some industrial supply hardware stores have microswitches, but they can drive only an amp or two. So you will also need a relay or contactor that can drive the 1 HP motor.
    Bob S
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook