Way back I thought a good middle school project would be
to race by R/Cing the car out a door, wait for it to find its way autonomously back through another door (This second door would have a naked 150W bulb at its threshold.), then repeat the cycle some number of times. The R/C - autonomous toggle to be controlled by powering ON and OFF the radio transmitter. If the transmitter's power is ON, the PIC detects activity from the radio receiver and switches control over to the original system.

Advantages of that idea are:
1. No need for proportional controls. A toy level car will do.
2. Photo cells are much less expensive than sonar sensors.

A problem is that the kit requires six DPDT coil driven relays: two for PIC generated steering, two for PIC generated wheel control and two for toggling between PIC control and R/C control. These are inexpensive, but add complexity in kit construction.

This car could also do the swarm-after-teacher who's carrying a naked bright light game. I've been changing my focus from teach-the-student to teach-the-teacher. What do you think? The RC system itself is full of "How things work" answers.

Your thoughts?

Ken