Detect Motor Burnout?

VEX V5 Technical Support UNOFFICIAL Tech Support
1

We have seen many V5 motors go bad w/out any sort of indicator (light red, brain ‘sees’ it)

However with tandem motors (lift) this is an issue b/c it is not really apparent.

My Q is is there a was we can determine if a motor’s OK via VEXCode or ??

Looking at the motor() API it looks like everything is whilst the motor is already running.

So maybe a separate chk_motors program that .spins() each motor and looks for .isSpinning() or reads the encoder?

Any thoughts are appreciated!

2

Motor burnouts will be indicated on the brain log via the temperature levels.

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3

Thanks - good idea - I’ll look at this! You mean after robot’s been run to look at this?

One of our teams brought us a problematic robot and suspect the motor’s temperature were all room temp.

4

For 393 motors we built a tester jig to test their performance. It was a motor that spun 4 wheels with an encoder on the shaft. We spun them forward for 5 seconds then backwards for 5 seconds and just looked at the values to tell the quality of the motor.

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5

great idea as well. However I was hoping to test motors on the robot - say between matches.

IDK why our school burns through them like we do - but you know that Murphy…:upside_down_face:

6

Yup. After it is run you can unplug a motor to get the screen pop up with the button for the log. If the motors reached the temperature limits it’ll list it there.

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7

Thanks all for your input.

What I wanted was a quick program students can run between matches to check motor’s working.

While not sophisticated, this is what I’d envisioned and welcome any input. The one thing I haven’t figured out is when motors are directly coupled If the encoder works but motors doesn’t this may send a false positive…

/void pre_auton(void) {
  // Initializing Robot Configuration. DO NOT REMOVE!
  vexcodeInit();

  // set motor defayults
  setUpMotor(L_Drive, 10);
  setUpMotor(R_Drive, 10);
  setUpMotor(L_Lift, 10);
  setUpMotor(R_Lift, 10);
  setUpMotor(Claw, 10);

} // end pre_auton

// DEFAULT MOTOR SETTINGS
void setUpMotor(motor(M),int D) {
  M.value();
  M.setMaxTorque(90, percentUnits::pct); // set torque
  M.setTimeout(3, timeUnits::sec);       // set motor timeout
  M.resetRotation();                     // reset encoders
  M.setStopping(hold);                   // hold
  M.spinTo(D, deg, 15, velocityUnits::pct);
  dspMotor();
  wait(2, seconds);
}

void dspMotor() {
  Controller1.Screen.clearScreen();
  Controller1.Screen.setCursor(1, 1);
  Controller1.Screen.print("Drive L: %3d R: %3d",
                           L_Drive.current(amp)/1000,
                           R_Drive.current(amp)/1000); // L&R DRIVE
  Controller1.Screen.setCursor(2, 1);
  Controller1.Screen.print("Lift  L: %3d R: %3d",
                           L_Lift.current(amp)/1000,
                           R_Lift.current(amp)/1000); // L&R LIFT
  Controller1.Screen.setCursor(2, 1);
  Controller1.Screen.print("Claw: %3d",
                           Claw.current(amp)/1000); // CLAW

} // END TEST MOTOR
8

Oh, that sounds pretty cool! I find it easier to just go through the log but if you want you can try adding temperature like this:

Motor.temperature(percent);

I’ve never used this before but if you want to try it it may be worth a shot.

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9

maybe this’ll help you out, but you’ll have to convert it to vexcode-c++:

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10

Thanks - yes, the temperature and current are great metrics - just not sure how to log these & get kids to read the log…

11

you don’t. My reference to a log was to the one automatically generated by your brain when you plug in motors, unplug them, when a motor overheats, etc.

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12

thanks - this is good info !

U got me thinking & it hurts! :face_with_raised_eyebrow:

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13

got to look at that! I knew the brain would throw messages and display real-time stats - must be a way to query this

Again - our kids are middle school and it’s hard enough getting them to remember to check fasteners - asking them to rifle through brain menus equates to work & guarantees they won’t…

14

Totally get it. If you have any trouble finding it I can work up a gif tomorrow if you’d like.

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15

that’s mighty kind of you - you prompted a change in code - instead of using motor position I am reading the motor current! seeing motor.stop(hold) anything with a load should show up - the problem is drive motor but that’s easy to tell anyway…

Still got to look at the brain’s data - that’s a good one…

16

As a side note, the prefered way to get to the Event Log is here: https://help.vex.com/article/464-how-to-access-event-log-on-the-v5-brain

The Event log can be checked while a program is running too.

The hardware is designed to handle hot plugging, but by unplugging the motor to get the pop-up error, it does create unnecessary events in the log.

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