Stalling Robot Please Help

VEX V5 General Discussion Technical Discussion
#1

So me and my teams robot keeps stalling out while driving. We can drive for about 8 or so seconds and then the motors just stall, all the other motors work fine. The motors we are using are 393s. I have tried just about every problem solving tip out there that i can find, the main ones i have tried are circuit breakers are not tripped, code is fine and i have even completely replaced the cortex and i just can not find out what is wrong with the robot.

#2

Are the motors hot (burned out)? Also, are the gears inside of the motor damaged or stripped?

#3

You’re probably asking too much of your motors. How many are you using on what ratio? Also check for excessive friction

#4

Try to run a simple “run motor” code on it. See if they still stall. If they do, try to pull the shafts out of the motors and see if they can spin themselves. If they do, your problem is in the build. (Gear ratio, friction, etc.)
If they don’t your issue is either the motor itself or the port. Try to swap the port. (Swap the motor controller first, if it’s Cortex.) If it still doesn’t;t work, swap out the motor.

#5

Pick one:

  1. My robot is over-geared.
  2. My drive system has very high friction.
  3. Both 1 and 2
  4. Some really unusual problem like a failing but not yet dead motor speed controller on all drive motor ports simultaneously.
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#6

To elaborate on the check for excessive friction, it’s usually done by disconnecting the motor(s) and moving the mechanism they were attached to by hand. It should be effortless for a human to move the mechanisms that we’re asking these motors to move. If it’s a free spinning mechanism like a wheel, you should be able to set it spinning and have it continue for several seconds. If it immediately comes to a halt when you let go, it’s bound up.

Causes of excessive friction are usually things like lock collars rubbing against things (there should be a little play of the axle along its axis to avoid this) or bearings that aren’t aligned, causing axles to bind up in their bearings instead of spinning freely. Chain sprockets that are not coplanar can also cause chains to bind. Usually you can avoid this by having at least one sprocket be a little free to move on its axle. Chains that are too tight or too loose can also lose energy.

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#7

i check for that next time my team meets

#8

i don’t know the exact gear ratio of the gear train. But it is a speed gear train so big to small using a chain system, and the chain is not super loose nor super tight.

#9

i will have to try this thanks for the tips

#11