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Re: [SeattleRobotics] Do I have a damaged motor?

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  • Jason Hsu, embedded engineer, Linux user
    The wheel attached to the suspect motor is much harder to turn by hand than the known good motor. However, I haven t tried the other steps you suggested. I
    Message 1 of 3 , Aug 19 5:41 AM
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      The wheel attached to the suspect motor is much harder to turn by hand than the known good motor. However, I haven't tried the other steps you suggested.

      I ordered two replacement motors from Acroname last night. I'm pretty sure (though not 100%) that the suspect motor is bad.

      On Wed, 18 Aug 2010 21:19:11 -0700
      Wim Lewis <wiml@...> wrote:
      >
      > Hmm, your troubleshooting steps all sound good to me.
      >
      > There could be a mechanical problem, either inside the motor, or perhaps
      > the wheel is dragging against something. So the motor might not have
      > enough torque to turn with the amount of current supplied by the motor
      > driver, but when you connect it directly to the voltage regulator
      > perhaps it supplies enough current to overcome the extra friction.
      >
      > A couple of ideas you could try:
      >
      > - Turn the wheels by hand and see if the troublesome motor is noticeably
      > harder to turn. Do this with the wire disconnected from the motor so
      > that motor braking doesn't complicate things.
      >
      > - Measure the resistance of the motor itself, see if it has about the
      > same resistance as its counterpart. Maybe it has a bad connection
      > internally. OTOH, small DC motors sometimes have kind of irregular
      > resistance because their brushes don't make perfect contact, so this
      > isn't a really conclusive test.
      >
      > - Measure the current going through each motor when the robot is trying
      > to turn it. If the non-moving motor has much higher current than the
      > moving motor, it's probably stalled (suggesting it's a mechanical
      > problem). If it has much lower current, then there's probably some
      > electrical problem.
      >
      >
      >
      > ------------------------------------
      >
      > Visit the SRS Website at http://www.seattlerobotics.orgYahoo! Groups Links
      >
      >
      >


      --
      Jason Hsu, embedded engineer, Linux user <jhsu802701@...>
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