Pathfinder is a two-wheeled, two-motor vehicle without any sensors
attached. It is an easy-to-build, easy-to-fall-apart vehicle. We have
included building instructions since it is no longer included in the
Constructopedia. We suggest using it as a vehicle (no pun intended)
for introducing RCX Code.
activity has two parts. Part 1 is designed as a transition between the
Wall Hugging Mouse and programmable robots. In this part, you will
demonstrate running M. Pathfinder’s base without the RCX, showing that
the unit can run on batteries alone and does not have to be programmed
to run. You will show students that M. Pathfinder can run with or
without the RCX. When connected to batteries, it can run forward or
backwards, turn right or left, all depending on wiring. You will then
demonstrate how M. Pathfinder’s behavior can be controlled through a
program rather than through wire switching.
Part 2, students build the modified Pathfinder, following the M.
Pathfinder building instructions. They then run it using the program
in slot #1. (This program is downloaded onto the RCX when firmware is
installed.) Students will notice that M. Pathfinder goes forward, but
doesn’t stop by itself. In order to stop it, they must catch it and
turn it off.
Next,Before You Begin (r-r) students will follow the activity sheet to help them figure out
how to make M. Pathfinder move and stop on its own, using the On,
Wait for, Off, and On For command blocks.
point students will be ready to use the newly acquired commands to
write their own programs, instructing M. Pathfinder to move in a
variety of ways (e.g., zigzag, go around a box). Finally, they will
program M. Pathfinder to go towards a wall, hit it, and go backwards.
It is important that all students solve this problem before they move
on to work with touch sensors.