Build Your Own Combat Robot

232 Build Your Own Combat Robot
FIGURE 10-14
Schematic of a set of
robot-crushing claws.
The challenge of a crusher design lies not only in achieving the force required,
but in designing a claw structure strong enough to deliver the force without collapsing.
Most crusher designs use claws that taper to narrow blades or spikes to
focus the force on as small an area of the target’s structure as possible. The claw
not only needs to be designed to survive its own crushing force, but must be rigid
enough to avoid bending on hits from spinners or off-center forces from closing
onto a sloped surface.
Figure 10-14 shows a schematic.
Ideally, a crusher’s claw should be large enough to bite into a sizable chunk of
the opposing robot. A claw that’s too small will not be able to damage much more
than outer armor layers or small protruding pieces; and if used against a large target
with curved surfaces, a small claw might simply slide off the target without digging
in. Typically, you will want your claw to open as large as the height of the largest
robot you expect to fight, and be long enough to get at least a third of the way into
your opponent for maximum damage potential.
You also want the claw to close as quickly as possible. A claw that takes more
than a few seconds to close will likely allow the opposing robot to escape before
being crushed. A closing time of one second or less should prevent even an agile robot
with high ground clearance from getting free. Of course, the combination of high
force and high speed requires a powerful motor to drive the claw mechanism. A
variable-displacement pump on a hydraulic-powered crusher will allow you to do
both with less power—the hydraulic system can run in high-speed, low-pressure
mode until the claw makes first contact, and then switch to high-pressure mode
for the main crushing action.