Loading ...
Sorry, an error occurred while loading the content.

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

Expand Messages
  • Wim Lewis
    ... 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
    Message 1 of 3 , Aug 18 9:19 PM
    • 0 Attachment
      On 8/18/10 4:19 PM, Jason Hsu, embedded engineer, Linux user wrote:
      > I've built the workshop robot. I'm only able to get the right wheel to operate. When I apply voltage to the left wheel, I hear the humming noise of the motor, but it does NOT turn. The only way I've been able to get the left wheel to turn is by connecting it directly to a voltage source.

      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.
    • 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 2 of 3 , Aug 19 5:41 AM
      • 0 Attachment
        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@...>
      Your message has been successfully submitted and would be delivered to recipients shortly.