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  1. #1
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    Shoot my actuator idea down please...

    I floated this idea a while back and received essentially no positive responses. Despite that fact, I figured I’d throw it out there one more time so someone can tell me why it wouldn’t be the most cost-effective method for powering an actuator.

    Here is the motor:

    At less than $300 and with over 20 horsepower, an actuator driven by this setup would require very little gear reduction, would be capable of massive force, and might be capable of travel rates exceeding a meter-per-second. For those not familiar, this is an outrunner brushless motor. The outside can spins instead of a typical motor where you have an internal core spinning. The result is massive torque and lower rpms. Moreover, these are extremely elegant motors, virtually silent and extremely well built.

    http://www.hobbyking.com/hobbyking/s...ner__(100cc_eq)

    In order to power the motor, a simple speed control such as the one below could be used:

    http://www.hobbyking.com/hobbyking/s...hless_Boat_ESC

    This motor controller is not only cheap, it has the ability to brake the motor allowing for precise stopping in the target range of motion.

    From a mechanical standpoint, I can easily think of several ways in integrate this system into an actuator so I certainly can’t imagine that be a substantial problem. However, I am no electronics expert, so I would not have a clue how to integrate this device electronically…. so maybe that’s where I don’t understand why this wouldn’t work.

    Anyway, shoot the idea down so I can move on to other plans.


    Pete

  2. #2
    150+ Forum Groupie Roland's Avatar
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    Re: Shoot my actuator idea down please...

    Hi Pete,

    I did some measurements on brushless outrunners that I use in my electric RC airplane models.

    What I found is that these brushless motors have fantastic torque and high efficiency when running at higher speed, but the torque at stall condition is really low. I could easily hold still a 250W motor with my hand, and it would just make a high pitched squeel sound, but hardly develop any force.

    I think it is due to the driver that senses back emf for making the correct rotating anchor field. Without rotor movement, there is no back EMF and the driver will not function well.

    Also most drivers will be one direction only, though I have seen two direction units as well.

    Brushed DC motors have good torque all the way to zero speed. They are my favorite.
    RR

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