I have an intermittent problem. Perhaps a few times per week, the motors on my Magni will NOT MOVE in response to commands. I can source commands using teleop-twist-keyboard or the Logitech game controller. But when this problem is happening, the motors either will not move at all, or will turn a little, in spurts, and sometimes pause for long periods. There have even been times where I have held the joystick all the way forward, and fifteen seconds later, the wheels will operate normally - only to fail again five minutes later.
After a reboot, this problem is likely gone. However, some days, exhibit nearly 100% failure, even after a reboot. (It’s almost like a weather system statistical equivalence.) ~~ Anyway, while the failure is happening, I can inspect various things in ROS (i.e. cmd_vel) and confirm that the commands are getting through.
I sometimes get the feeling that some other system on the R-Pi is interfering with the transmission of the command to the motors.