Each step in the video begins with the parts required
for each subassembly laid out on the table. The parts are all
pretty easy to tell apart — none of the various hub pieces
and mounting brackets look too similar. The only
components that might be difficult to pick out at a distance
would be the fasteners, but those are all helpfully contained
within small bags that label the size of the screws.
The Agent 390 is essentially symmetrical, and one of
our favorite parts of the instructional video is that after
finishing a step, a link pops up on the screen to take you
back to the beginning of the step in case you need to do it
again (or five more times, in the case of the wheel
subassemblies). It’s a convenient way to avoid having to
blindly pull back on the video progress bar and hope you
hit on the right spot (like a tedious You Tube version of pin
the tail on the donkey).
Having two people work on the assembly at once
(being careful to mirror the instructions where appropriate)
made the process pretty quick. Sometimes the clamping
screws on the wheel hubs were a bit tricky to get tight, but
the right Allen wrench (or clever ways to increase torque on
the handle) will do the trick.
We were quite impressed with the design of the kit.
Standoffs from the inner frame to the outer brackets ensure
that the tracks stay on track, but the rubber belts seem so
well fit to the kit that we doubt the tracks would ever want
to go AWOL anyway. All of the shafts for the tracks run on
ball bearings, and the smoothness of the ride is awesome.
The kit strikes us as very efficiently designed, with cleverly
shaped brackets joining the major frame pieces while taking
up minimal space.
The tracked base has plenty of room to accommodate
a control system and whatever kind of mechanisms you
might dream up. The motors sit at the back of the robot,
leaving almost the entire 12” x 18” footprint of the body of
the robot free on its underside (and the entirety of the
footprint free on the topside of the bot). So, what could we
do with all of that space?
Yes, We Canipede
Before getting deep into mechanism design, we
wanted to make sure we could get the base moving around
first. There’s plenty of room for any kind of control system
you could want to include. Our plan was to mount all of
the control system components on the underside of the
robot so that the entire top surface could be dedicated to
the mechanism. With the proper motor driver shields, an
Arduino-based control system could be a great fit. However,
we opted for a system that we had used before, and it
would give the bot the cool distinction of being controlled
using our smartphones.
The 2CAN and Canipede Robot Control Module from
Cross The Road Electronics (CTR) last appeared in the pages
of Twin Tweaks back in June 2011, when we used it to
control our prototyping platform, Protobot (which has
recently taken up the hobby of punkin chunkin). The 2CAN
and Canipede operate on a Controller Area Network (CAN)
which is the protocol normally seen in automobiles. CAN
works well in high noise environments, but the real appeal
of the 2CAN and Canipede is that they were designed to be
implemented without any programming required — all while
offering all of the ports needed for sophisticated robot
control (including eight PWM channels, eight analog inputs,
four digital l/Os, eight solenoid channels, four quadrature
encoder channels, four relay outputs, and two CAN
Twin brothers hack whatever’s put in front of them, then tell you about it.
SERVO 04.2016 53
WIRING UP THE MOTOR.
HAVING A WHEEL-Y GOOD TIME.
WOAH, WE’RE HALFWAY THERE.