Problems with the MCB v5.0

Hello again!

I’ve been trying to test some wheels on a ubiquity MCB v5.0, however they act strange, one doesn’t move at all and the other whenever something tries to move it, be it manually or using ros teleop, starts to move forward uncontrollably, not stopping until turned off. The wheels seem fine and so does the board, however they don’t work together. The wheels are also from ubiquity, however I don’t know if they are from the MCB v5.0, would that be a potential cause for the problems, or is it something else that i missed?

Thanks for the help!

The most likely causes are in this order (If it used to work then stopped working recently).

  • Wheel cable not fully inserted for the inline jacks
  • One or more wires is not connecting properly on the terminal strips. I will assume you have not ever unscrewed the wires from the jacks and/or replaced the cables that attach to the board screw terminal strips. Verify the 3 large wires are firmly screwed in with proper colors where yellow is highest, then Green then blue and none of them short out with the cable next to it. The 6 small wires are for wheel encoders and the white wire may not be attached for things to still be ok.
  • If you have been trying to do PID tunning and the cooefficents are wrong then eratic behavior can happen. Did this all start after you tried doing PID tuning process?

When checking the wires to the terminal strips be sure the screw terminals are holding the bare stripped wire and not just smashing down on wire insulation.

I needed to change the wheel cables, so they’re not the original, however they are fixed correctly on the board. I’m not doing the PID tuning, i’m just trying to control the robot using ros teleop.

Another question, how does this calibration work? I’ve never done it, are there any instructions or manuals on how to do it?

I don’t know where you got your wheel cables so that of course is an unknown.

If you have official Magni wheels and official magni motor cables then this picture documents correct wiring for both of the cables.

Magni Wheel Cable Wiring

Additional debug information to try:
Turn on the magni with the red wheel power switch in the off position (the red led on the power connector/switch board will be off so there is no high voltage to wheel drivers)

You should be able to measure with a voltmeter on the tiny colored wired right on top of the terminal screws themselves these things:

  1. Black to Red wire must be solid and steady 5 volts
  2. An oscilloscope with ground clip on the magni board ground obtained from either of the two center ground pins on either of the two top-side 4-pin white Main and Aux connectors. BE CAREFUL TO NOT SHORT GROUND TO EITHER 5V or 12V power. With that ground and motor power switch still off you must be able to see high to low pulses on each of the yellow, green, blue screw tops on the terminal strips in the pictures. Manually rotate the wheel and all 3 of these must show digital high to low changes of about 0v to 5v when you rotate the wheel.