[Ken Streeter]

Originally Posted by kitare102

3042 got their robot fully operational last week and has since found that, even under fairly little strain, the drive motors get extremely hot. ... 1/8 inch drop center. ... I recognize that the length of the drive train gives it a lot of scrub...

Do all 4 drive motors get hot when practicing? If so, I would temporarily ignore the 4-amp difference between right and left drive current.

My first guess at high current draw on that robot from looking at it would be that the amount of force required to get it to turn, being a 6WD skid-steer, is way too high. I would suggest a "powered-off robot spin-in-place test." With the robot powered off and sitting on carpeted floor, put your finger down low on a side corner of the robot frame, (for example, at the front left corner, pushing sideways) and push on the robot to try to rotate it. Can you do this with one finger? two fingers? do you have to push real hard to get it to rotate? However much push you are needing to exert is an indication of how hard the robot needs to push in order to turn. I speculate that drive base is extremely difficult to turn in place.

We had similar issues with our 2011 6WD robot, which was a very similar configuration. It looks like your frame is relatively flexible. The idea with a 6WD drop-center wheel configuration is that the robot weight is primarily supported by the center axle, with less weight on the front/back corners. However, with only 1/8" of drop (that really isn't very much) and what looks like a fairly flexible frame, I wouldn't be surprised if the corner wheels are still fairly heavily weighted. The amount of drop needed depends a lot upon the rigidity of the frame. 1/8" might be enough for a very rigid frame, but you might need a lot more with a more flexible frame. Does the robot seem that it is able to "rock" back and forth from front to back at all? If not, there is likely still too much weight on the corner wheels.

Anyway, with our 2011 robot, our fix was to switch to omni wheels in all 4 corners. Problem solved. Other alternatives are to increase the amount of drop, make the frame much more rigid, or switch to low-traction wheels in the corners.

By the way, to help diganose if the problem is related to turning, you could use the SmartDashboard (or regular Dashboard, if using LabView) to continuously display the PDP current readings for each motor. While the robot is being driven straight forwards and backwards, look at the current readings on the display for all the motors and record those values. Then, repeat the experiment while the robot is spinning in place. If there is a big difference in those values, you have confirmed your problem is related to wheel traction resisting turns. If the current readings are very high for both front/back and spinning in place, then the problem is likely mechanical resistance in the gearbox and drive system. However, my guess is for difficulty turning.