First of all, I reached a thought that your performance could have no issues. That is just my thought. If anyone has other views, please add a comment. The reason I have finally decided it is as follows:
I re-read the 2017 rules and found a hint to make clear the boundary. It is a quotation of 1.4.1.
1.4.1. Teams are encouraged to design their robot(s) with a communication function. Robots are encouraged to communicate with each other on stage, for example, with a Bluetooth communication option (refer to 2.7 and 2.8).
There must be no communication with off-stage and on-stage devices.
Under this rule, teams are not allowed to use communication from any electrical devices during a performance. That's because communications from any devices which are handled by students directly are considered as a remote controlled. The devices could be a PC, keyboard, phone, tablet, game-controller and so on. The RCJ-05 soccer ball or IR pointer devices could also be included.
However, this will apply just to communication between robots and devices but not for using cameras or sensors, because this is a rule for communication.
On the other hand, use of camera and sensors is encouraged in the rules. Especially we are welcoming to try newer or higher technologies. So the performance using a camera should be accepted, it would be another matter whether it is rewarded higher at the performance judging or not though.
That's just my two cents. I'm looking forward to hearing your students' growth through the robotics activities.