Build Your Own Combat Robot

234 Build Your Own Combat Robot
FIGURE 10-15
Robots carrying
spears.
The goal with a spear design is to maximize the impact when the weapon head hits
the target. The force behind the weapon at the point of impact does not matter, because
the effect on the target will be determined entirely by the kinetic energy of
the spear at the moment of impact. The kinetic energy of the spear is proportional
to its mass times the square of its velocity, so increasing the speed of the spear will
do more to make it an effective weapon than increasing its mass. Excess force on
the spear at the moment of impact will mainly have the effect of pushing the
spear-armed bot and its target away from each other; the traction holding the bots
in place on the floor is small compared to the forces required to punch through armor.
Figure 10-15 shows such robots.
Ideally, your spear bot should strike the opponent near the end of its travel for
maximum effect. In practice, however, this will be difficult if not impossible to arrange.
In most cases, the spear will strike the target robot after only a fraction of its
travel. If possible, you should design your spear to accelerate as much as possible
early in its travel.
Most spear designs use a pneumatic cylinder to fire the weapon. With a pneumatic
ram, the top speed of the weapon is limited by the rate of gas flow into the
cylinder. All components on the gas flow path from the storage tank to the cylinder—regulator,
valves, tubing, and fittings—should be made as large-bore (internal
diameter) as possible for maximum flow rate.