Build Your Own Combat Robot

210 Build Your Own Combat Robot
Wedge bots are vulnerable to lower, faster, and more powerful wedge bots, as
well as lifters and clamp bots. A wedge bot is helpless if its wheels are lifted off the
ground, and the fact that most wedges have ground-scraping armor and scoops
means that anything that gets underneath them is very likely to raise the wheels off
the ground. If possible, design your wedge bot to be able to run upside-down, or to
be able to right itself quickly if flipped over. Also give your wheels as much clearance
as possible, and design your wedge so that it still has traction even if the front
or one side is lifted off the ground.
Lifter Bots
Lifter Design
The lifter weapon design was first used in X-1 (Robot Wars, 1994). Examples of
lifter bots include Biohazard, Gamma Raptor, and Voltronic. A lifter bot features
an actuated arm that’s designed to hook under the opposing robot and lift it off
the ground, flipping it over or carrying it about.
Like the wedge, the lifter is designed to get underneath the opposing robot and lift
its drive wheels off the ground. The lifter uses an active device to do so—an arm
driven by hydraulics, pneumatics, a geared electric motor, a powerful spring
cocked by a motor, or an electric linear actuator—with enough power and leverage
to tilt or lift up the other robot. The end of the arm is often wedge shaped, or
blended into a wedge-shaped front; and in many cases, it has grip-enhancing
hooks or teeth. Figure 10-3 shows a lifter robot.
The advantage of a lifter over a wedge is the ability to lift the other robot’s
wheels off the ground independent of movement. While a wedge can only lift the
opponent higher by shoving itself under its opponent, a lifter, once underneath the
opponent, can lift it up as high as its arm can go while remaining stationary. A
well-designed lifter can drag its opponent around the arena freely, while a wedge
can only push its opponent forward.
Most combat bots are designed to be low and wide, and won’t fall over until
tilted 90 degrees or more. To flip opponents over with a lifter, you will need an
arm with a maximum height comparable to the width of your targets. Usually, this
means the pivot point of the arm is located nearly at the back of the robot, and the
arm should extend on top of or down the middle of your bot to the front. Arms of
this type can often double as self-righting mechanisms.
The most common drive systems for arms are linear drive actuators, either electric
ball-screw types or pneumatic cylinders. Electric screw actuators, consisting of an
electric motor driving a telescoping cylindrical assembly through a nut and screw
mechanism, make for a slow but powerful lift. These devices have the advantage
of being self-contained and functional in one unit, needing only an R/C relay or motor
controller to extend and retract. Pneumatics is a faster option. A powerful pneumatic
system can actually hurl the opponent into the air (see the description in the