Rock and Rover
READY FOR ROVERING.
particularly well-suited to such a design; the multiple
mounting holes on each frame piece make basic
adjustments of the link dimensions quick and easy.
Leftovers from the 3-in-1 Rover kit and the bag of extra
parts had far more than enough frame pieces to build our
arm and claw mechanism, and soon we were ready for
Red Planet Rover, Come On Over
Before we attached our four bar linkage to the gear
mechanism, we wanted to confirm that our trusty old
Futaba radio and receiver would play nicely with the VEX
motor and the rest of the moving parts on the Rover itself.
We wired up the mechanism – motor to receiver and
battery to receiver — and fired up the Futaba.
The mechanism sprang to life and the large
gear began to turn ponderously, much like the
relaxed pace of an ancient water wheel on a
lazy stream. The slow speed was expected
given the gear ratio, and we hoped that would
also translate to big enough torque to raise a
long arm and a rock sample at the end of it.
Now, we had a working gear train and a
claw assembly. Fastening the components
together was made delightfully easy by the
serendipitous alignment of the Minds-i and
VEX mounting holes. Before mounting the
whole thing to the robot, we wanted to
ensure that the claw operated the way we
intended. Performing any redesigns would
be much easier before attaching the arm to
When we fired up the arm, we were
pleased to see that once the claw opened or
closed the entire arm would raise or lower.
Unfortunately, the claw opened before raising
the arm, and closed before lowering it. This
was the opposite of what we wanted to do, and it pretty
much looked like the claw was flipping off its careless
creators. When we took a second look at our mechanism, it
was obvious why it was happening.
NAVIGATING TOUGH TERRAIN WITH EASE.
SERVO 11.2012 71