We had a
mulit-robot demo at MARM last month in a lecture room at Rutgers. The playing field was about 20' x 15', with two goals. The teams ran informal demos and let people try their hands at driving, running one robot at a time mostly.
One thing which we will do the next time is have channel switches to allow running two robots with radios; tethers are okay, but radios are better. We didn't have any incidents, but a master emergency stop would be a good thing to have, at least for peace of mind.
Team 103 did a lot of demos at
the SBS Conference last year, too. There, we drove the robot all over the exhibition hall, gave driving lessons for attendees (everyone got a robot drivers license) and held a drag race with SICO (guess who won). No incidents other than a 6 yr old trying to drive the robot through a table, but an e-stop would have saved some anxiety. The key in an open area like that is to have people watching and anticipating to avoid incidents.