Build Your Own Combat Robot

Chapter 3: Robot Locomotion 45
Tank Treads: The Power of a Caterpillar Bulldozer in a Robot
Tank treads seem to be the ideal way to make sure your robot has the pushing
power to allow it to decimate an opponent in combat. Hey, they’re called “tracks”
because they provide a lot of traction, right?
We’ll call the ones robot builders have used “treads” from here on. The military
uses treads in tanks to demolish a much larger and more menacing enemy on a
rugged battlefield. Earth-moving equipment can bounce across rocky ground
pushing many tons of dirt, as the two sets of treads dig in with all their might.
These things seem to be the ultimate means of locomotion for a winning combat
robot. This could well be the situation if the contests were held in a rocky and hilly
locale, but most competitions take place on fairly smooth industrial surfaces. All
the same, let’s examine the construction and use of tank-type treads or tracks.
Many first-time robot builders are drawn to treads because they look so menacing.
Treads come in two basic sizes—massive off-road and toy sizes, and there is
no similarity between the two. The toy variety is just a rubber ring with “teeth”
molded into the rubber. The larger off-road–size treads consist of a series of interconnected
metal plates, supported by a row of independently sprung idler wheels.
The construction of interconnected plate treads is complex and should be left to
experts with large machine shops. Peter Abrahamson has built a very impressive
305-pound robot named Ronin. The aluminum tank treads were custom machined
for this robot. Each side of Ronin can rotate relative to the other, thus improving
the overall traction capability of this robot. Figure 3-2 shows a photo of Ronin
climbing a log.
FIGURE 3-2
Ronin—a true
tank-driven robot
with an
independent
suspension system.
(courtesy of Peter
Abrahamson)