[kitscuzz]

Try checking the tilt variable in tracking.c
If it exceeds a certain value, then your camera is looking really high up, and you need to stop.

Another idea (a bad one with the possibility of two lights), is to use blobsize. Blobsize is in the variable (unsigned int)T_Packet_Data.pixels

Note that both of these are aribtrary values, they depend on how you set up your equipment. If your light is sitting at the same height as your camera, the tilt will never change and the robot will never stop.