Robot doesn't turn in high gear

[newton418]

Originally Posted by Al Skierkiewicz

This is another one of the myths of electrical design. The Rockwell blocks are designed for continuous current of 85 amps per block. The 40 amp breaker will function with up to 600% of it's current trip rating for several seconds. Neither of these devices limit the current to that of their ratings.

I was aware that the 40 amp breakers could be pushed past their limit for small amounts of time, but decided to design the drive train such that we wouldn't need to constantly push the breakers, since we could get sufficient performance at 40 amps. I am much less familiar with the Rockwell blocks, since they are new and I do not work on the electronics. I figured that since they are rated for 85 amps they could be pushed past this limit, but I have no idea by how much or for how long. Could you further explain what the Rockwell blocks can actually handle?

As for the resistance in the circuitry, we kept the wire lengths to a minimum, and will definitely be more conscious of it in the future; however, I do not understand how this would fully explain our problem. At 40 amps, a small CIM outputs ~.8 N*m (please correct me if my calculations are wrong), and IF we could run them significantly beyond this, say, near stall current, then even if you take the ~2.2 N*m stall current then the wire resistance would have to be somewhere around 76 WF. Though I am not the most familiar with our electronics system, I am confident it does not have this much resistance. Now, I did make several assumptions when calculating the torque needed to turn in 2nd gear, so in actuality .8 N*m of torque might not have been enough; but, assuming that the difference is negligible, how do you explain the problems we faced?

Also, I have just talked to our electronics/code mentor and he suggested that we bypass the Rockwell block to see if it is (at least in part) the problem. He also suggested we monitor the voltage on both sides of the Rockwell block using a USB DAQ, so when we get those results I will make sure to follow up on this.