Towing your robot

Robotics and electronics discussion Mechanical design and actuators
1

Hello,

I have a question about towing your robot when it is offline. I will have two wheels permanently attached to DC motors, which in turn are attached to the 30 amp motor controllers. When everything is off (let’s say batteries removed from the robot) is it then safe to manually tow or push it around?

As far as I understand DC motors, they will act as generators when manually turned, sending back current to the controllers. Can these handle such currents when they are switched off (not powered)? Or is it safer to put a (high current) switch between the controller and one of the two motor wires to physically detach it when I want to do some pushing or towing? Will this then not destroy or hurt the motor, since the current has nowhere to go?
And what when the power is on, and I push the robot around?

Sorry for this maybe strange question, but better safe than sorry for my first bot :slight_smile:

Thank you

2

Hello,

You should probably be okay with towing the robot, especially if you tow it slower than it runs when powered. With most motor controllers, the motor voltage will show up on your motor power supply, which might be the supply for the rest of your robot, which would mean that back-driving the motors will power up your robot. As long as your other electronics won’t do something bad with less than the usual power supply, I don’t think anything would be damaged.

The motors will definitely handle being driven without anything connected. I would be more concerned about he gears handling it, but if you’re talking about a big robot, the gears are probably strong enough. (If you try to manipulate the output of a micro servo, the small plastic gears can break.)

- Jan