Non-MC29 driven motors cutting out

We built an H drive with 4 high speed motors driving 2.75" omnis. The robot weighed in at 20.4 lbs., and it performed great throughout all of our practicing.
While at the state comp. last weekend, we made the mistake of positioning our robot wrong for the autonomous period. We faced it towards towards the wall, where it drove into the wall for 15 seconds. After that, for each driver control period, after approx. 30 seconds, a drive motor from the left bank of drive motors would cut out, as if the ITC’s had been tripped. The right motors, which were plugged into MC29 converters were fine, and exhibited no issues. What really puzzled us, is after like 15 minutes we still had the problem. Normally, we would have just swapped out the MC29’s, except the left drive motors were plugged into ports 1 and 10. We tried swapping out the cortex, to no avail, and it cost us the competition, in which we finished dead @#%&ing last. :mad:

Did we burn out a motor? They still work for a brief amount time before cutting out, and eventually respond again, but not in time for a competition.

Are you sure none of your axles got bent or something else from the collision caused too much friction someplace on that side of your bot?

Cant be answered without knowing your motor to wheel assignment.

Try replacing the motors.

Do you have sensors like a sonar, a accelerometer, quadatures, or IMEs?

With the sonar or the accel, it would be beneficial to prevent this from happening again by having an expected value, and if the robot doesn’t reach that value in a reasonable time, stop all the motors.

This might also work with the quads or the IMEs, but if the wheels continue to spin, they will keep counting.

Just a couple thoughts. For more assistance, please post pictures or arrangements like jgraber suggested

No ptoblem, here are some pics.
Each wheel is driven by one motor, direct driven. No axles are bent. The encoders are not causing any problems. We are still puzzled.

Motor ports
1: LF drive motor (hi speed)
2: RF drive motor (hi speed)
3: LT lift motor
4: LB lift motor
5: RT lift motor
6: RB lift motor
7: empty
8: Claw motor
9: RR drive motor (hi speed)
10: LR drive motor (hi speed)

All motors are 393s. The lifts and claw have standard 100 rpm hi torque gears.
IMG_20150224_163518.jpg
IMG_20150224_163531.jpg
IMG_20150224_163546.jpg

Try plugging a motor that is not connected to anything into ports 1 or/and 10 and see if that works.

We tried swapping cortexes and it didn’ t solve the issue.

nvm, accidental dbl post.

Sorry if I’m being picky, but I just have to correct you.
Your robot’s drivetrain is a x-drive not a H drive.

The 2.75" wheels on x drives and heavy robots do not work out to well. They don’t roll well to begin with because they are such a small diameter and the rollers are the same size as 4" omnis, and when you put them on mat where they sink in and on a heavy robot it puts a lot more strain on the motors than an x drive with 4" or 3.25" would’ve.