Beginner - Stepper Motor - variable direction and speed

Discussion in 'The Projects Forum' started by honey_ryder62, May 28, 2009.

  1. honey_ryder62

    Thread Starter New Member

    Feb 2, 2009
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    0
    I'm very very new at this and am good with electronics but not robotics;

    I'm trying to create a type of swing that moves forward and backward based on detected motion. I want the entire process to run for no more then 30 seconds and hold before starting again for 5 minutes. I want it to move forward and backward initiated by movement but the speed to increase linearly until the final forward movement where it will hold then reset.

    I was going to use a PIR for the motion detection and understand when motion ceases the movement of the swing will as well...perfect.

    If it comes down to it I'm willing to forgo the linear increase in speed and use an H-bridge for just forward and reverse....if my understanding of bipolar steppers is correct.

    I've been looking around on forums and the internet and think that a bipolar stepper motor would be best and a micro controller for programming. I have no problem further researching and trial/error on my own. Once I have an idea of the components I will be using I can figure out how to piece them all together.

    I'm asking for any suggestions, websites or recommendations on parts that would be helpful.
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    What are you requirements for speed? Most steppers only go to 5000 steps/second, which is 200 RPM. And they can't start at full speed, but need to ramp up from 0. Torque can be problematic, too.

    You don't find examples of them now, but some time ago instruments like chart recorders used servo motors to position the pen. When built right, they had great characteristics - torque, sensitivity, proportional control, etc.

    Lacking one of those, an H-bridge controller may give you better results.
     
  3. honey_ryder62

    Thread Starter New Member

    Feb 2, 2009
    4
    0
    I don't need very much speed or torque, I can fabricate the swing to suit my needs in that department.

    do you know where I would go to investigate different as to motor specs and controllers?
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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  5. Wendy

    Moderator

    Mar 24, 2008
    20,765
    2,535
    Another way suggests itself, hobbiest servo motors are cheap, and it would be relatively easy to connect a 555 circuit to make it go where you wanted it to.
     
  6. Bernard

    AAC Fanatic!

    Aug 7, 2008
    4,170
    395
    A swing has a natural period, if you work with it ,amplitude can increase with little power, fight it and will need lots of power. Might check on pablien73 's progress with PIR. There are also solenoids.
     
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