Quote:
Originally Posted by chloe
We're having a very specific bizarre issue: - When rotating or strafing in auto or teleop with our mecanum drive, we will quickly experience a huge voltage spike and then lose communication and robot code. This means it's not a code error.
- This happens only when our robot touches the ground, not when it's on blocks
- This does not happen when we shake our robot during autonomous or teleop
- This does not happen when driving straight in teleop
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Could one of your wheels be "fighting" the other three at some point in time? You state that this only happens when all your wheels are on the ground (and they are coupled together mechanically). You may have to do a brute force, line-by-line review of your code to find this. You can also try disconnecting the motors from the motor controllers, one by one, to see if you can find one motor where disconnecting it makes the system not shut down. You can then focus on the code relating to that motor.
When you put mechanical energy into the shaft of the motor, it acts like a generator (regeneration), creating a voltage on the motor's input terminals. Usually, you see people talking about this when the robot is powered off and they are pushing the robot around to transport it
Based on my knowledge of 3-phase AC motors an motor controllers, I suspect that since your robot is energized and you are already applying a voltage to the motor terminals, when regeneration happens, the voltage generated by the mechanical energy being put into the motor shaft (by the other 3 motors) "stacks" on top of the voltage being applied to the motor terminals causing a high voltage condition (> 12V) on the input of the motor. There is usually a anti-parallel diode across the MOSFETs in the motor controller. In an output over-voltage condition, these diodes forward-bias and pull your input 12V up. Your control system senses the over-voltage condition and shuts down. I can confirm this with the people in our Motor R&D Group at work on Tuesday.
Quote:
Originally Posted by lopsided98
I wouldn't completely trust that voltage reading; whatever is happening could be causing the voltage sensor to malfunction as the system fails.
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This could also be true.