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Thread: Robotics, Motor Controllers

  1. #1

    Default Robotics, Motor Controllers

    Hi people,

    I'm working on a soccer robot, I need to control motors for it's
    movement. I have purchased the "Lynxmotion" "h-bridge" aswell as
    the Texas Instruments "SN754410". On initial inspection of
    instructions of each, it seems that they can only control the motor
    to be forward/reverse (I think the h-bridge may have one lower speed
    setting). I was just wondering, anyone whose used these motor
    controllers before, is this right? Can it really only control the
    motors to go at one speed or is the speed variable?

    Thanks
    James
    Last edited by ForumTools; 09-30-2010 at 06:26 PM. Reason: Forum Migration

  2. #2

    Default

    I believe that's what 'PWM' (pulse-width modulation) is
    for. It lets you enable an h-bridge for PART of the
    time, so you can control the motor speed. If you
    cycle pwm on a millisecond basis, the motor windings
    average the pulses to produce a smooth, though
    lower-speed motor movement.

    --- In basicstamps@yahoogroups.com, "ensignkim113"
    <ensignkim113@y...> wrote:
    > Hi people,
    >
    > I'm working on a soccer robot, I need to control motors for it's
    > movement. I have purchased the "Lynxmotion" "h-bridge" aswell as
    > the Texas Instruments "SN754410". On initial inspection of
    > instructions of each, it seems that they can only control the motor
    > to be forward/reverse (I think the h-bridge may have one lower
    speed
    > setting). I was just wondering, anyone whose used these motor
    > controllers before, is this right? Can it really only control the
    > motors to go at one speed or is the speed variable?
    >
    > Thanks
    > James
    Last edited by ForumTools; 09-30-2010 at 06:26 PM. Reason: Forum Migration

  3. #3

    Default

    On Oct 3, 2003, at 6:56 AM, basicstamps@yahoogroups.com wrote:
    > I'm working on a soccer robot, I need to control motors for it's
    > movement. I have purchased the "Lynxmotion" "h-bridge" as well as
    > the Texas Instruments "SN754410". On initial inspection of
    > instructions of each, it seems that they can only control the motor
    > to be forward/reverse (I think the h-bridge may have one lower speed
    > setting). I was just wondering, anyone whose used these motor
    > controllers before, is this right? Can it really only control the
    > motors to go at one speed or is the speed variable?

    Actually the H-bridge has three speeds: full reverse, off & full
    forward. The "trick" is to use Pulse-Width Modulation (PWM) to switch
    between off and ether of the full directions for a percentage of time
    proportional to the percentage of full speed. For example, to move
    forward at 50% of full speed you turn on the H-bridge for half the
    time. For 90% full speed turn on the H-bridge for 90% of the time.

    Most of the popular microcontrolers include hardware and/or software
    support for PWM.

    --
    Enjoy,
    George Warner,
    Schizophrenic Optimization Scientists
    Apple Developer Technical Support (DTS)
    Last edited by ForumTools; 09-30-2010 at 06:26 PM. Reason: Forum Migration

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