There are a variety of ways to do this. When teams are talking about monitoring current, it usually refers to a simple procedure to check during construction that all motors are drawing current in an expected range. Just a few teams do this real time during competition. A simple clamp on ammeter that clamps around one of the speed controller input wires is sufficient to check the current. An electrician usually has one of these devices in his/her toolkit. If you are interested in real time current sense search Stangsense on this site or on
www.wildstang.org.