Motor speed control

Discussion in 'The Projects Forum' started by Filoe16, May 14, 2013.

  1. Filoe16

    Thread Starter New Member

    May 7, 2013
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    Hello everyone

    I am busy working on a school project that I would like your assistance on. I am building a robot that plants and harvest fruits, now my problem is that the motor that drives the robot is too strong. I would like to build a circuit that can actually help me control the speed of the motor without using PWM.

    I am using a 24V DC motor which has a speed of 7100rpm.

    Can anyone help??
     
  2. tshuck

    Well-Known Member

    Oct 18, 2012
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    Why do you not want to use pwm?

    Anyway, what is your power supply? Have a split supply? Do you only need speed control, or direction too?

    What level of education is this for? Image processing is no laughing matter...

    Edit: You could also do mechanical gearing to reduce the speed, but you don't have control over it after that...
     
    Last edited: May 14, 2013
  3. wayneh

    Expert

    Sep 9, 2010
    12,145
    3,054
    By "too strong" you actually mean "too fast", right? I don't think you want to make a design based on the behavior (failure, stall) of the motor under load.

    If you need feedback control to slow the motor down based on tactile pressure (don't squeeze the ripe fruit into pulp), now you're talking about orders of magnitude more complexity.
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
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  5. tshuck

    Well-Known Member

    Oct 18, 2012
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    If it's the motors Dave linked, you will need to gear them down, as they won't be much good to a robot as-is.

    What are these motors for, moving the robot, picking the fruit, moving a camera, etc.?
     
  6. Filoe16

    Thread Starter New Member

    May 7, 2013
    7
    0
    I have a motor that controls the planting arm of the robot. The motor has too much power which makes the planting arm too fast so I want to reduce the speed of the motor, more like control it.

    @tshuck, I am working on a P1 project and I am only interested in controlling the speed as we already build an H-bridge for the direction. I am using a PLC and not a micro-controller so I figured it might not be that easy to use PWM.

    @Dodgydave that motor is the type I am using. I did not purchase the motor, I used one that I found only to find that the rpm is quiet high.
     
  7. tshuck

    Well-Known Member

    Oct 18, 2012
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    Being that you are using digital controllers, and don't need ultra-precise movement, PWM lens itself well, considering it is readily created by digital controllers. I'm willing to bet your microcontroller has a capability of doing PWM in hardware. Which microcontroller is it?

    Does this motor have enough torque to move the arm, let alone carry a fruit?
     
  8. Filoe16

    Thread Starter New Member

    May 7, 2013
    7
    0
    Yes, the motor has suficient torque. I am using a Beckhoff PLC
     
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