It seems natural to combine mobility and sonar with weapons.
This bot uses radar
to do obstacle detection
and to trigger the painful whacking motion.
A basic tank type
design with a small tread
footprint and dual motor steering
The whacking arms
use a large 40 tooth gear connected on
either side via a long axle and a touch sensor
to track the arm motion.
Underneath, a dual
axle worm gear setup moves the tank treads.
Unfortunately, this design loses a great deal
of torque and energy during
turning and movement over
rough terrain (carpet).
Here is the front
with that IR transceiver and the light sensor
mounted on top. Notice the rotation
sensor on the bottom that tracks turn radius.
Here is the quicktime
movie of the crusher in action.