The kickoff demonstration version of the camera driving code (if it's the version 2.4 FIRST released) looks like it might just have operated by driving at a slow enough speed such that it was stopped when it pushed lightly up against something (a leg, a goal).
It looks like the max forward speed was 150.
Code:
user_routines.c:38: const int speed_setting = 150; //forward speed setting (127 to 254)
user_routines_fast.c:31: extern int speed_setting;
user_routines_fast.c:154: if (speed_setting < 128 || speed_control > 254) //Check speed_setting for valid forward speed
user_routines_fast.c:155: speed_setting = 150; //If not valid number set to default
user_routines_fast.c:158: speed_control = speed_setting;