problems. The new radios and receivers also use binding, so
that a specific receiver only works with a specific radio.
RoboGames rules require that combat classes use 2. 4 GHz
radios with binding, so we went from our old Futaba to a
new Spektrum Dx6i six-channel radio.
Rewiring Troublemaker would require a bit more than
simply swapping out the old receiver for the new, however,
because we were making one other discretionary change to
Troublemaker’s electronic internals: upgrading the speed
The drive and weapon motors in a robot get most of
the glory and adulation in a design — like the lead singer or
the riff from the lead guitar. The drive and weapon motors
in Troublemaker were just fine. The drive train was
essentially unchanged since 2001 — the bot cruises along
on four direct drive Maxon motors that in a past life
operated the butterfly valves on an Indy car engine. The
motors are equipped with a 14:1 gearbox and all had about
2,000 miles of racing on them
(and fewer miles of robot
combat on them). The drive
motor for our weapon was an
old car fan motor of all things,
but it had held up admirably
and seemed fine during testing.
Speed controllers are also
essential, but often not as
flashy as the motors.
Sometimes the speed
controllers can steal the
limelight, like the base line in
The RageBridge 2.0 features automatic current limiting that
should (in theory) prevent the speed controller from
burning out (unless the board itself is shorted).
As folks that have burned out our share of speed
controllers, we were looking forward to testing out the
RageBridge — especially since one RageBridge included two
motor channels. Because of this, we were able to slim
down Troublemaker’s internal electronics from two Victors
to one RageBridge.
Setting the current ceiling is as easy as finding a small
slotted screwdriver, and the unit comes with a nice heatsink
plate that we mounted against our floor (with a layer of
dielectric paste in between).
We do have one gripe about the RageBridge — the
headers for the PWM cables were all pins. Our AR610
receiver also had pins for the PWM cables, so to go
between the receiver and the RageBridge we needed
female-to-female cables which are as hard to find as a
long-term guitarist for Guns N’ Roses post-Slash. We
were eventually able to find the connectors through
VEX, but that isn’t the biggest problem we had: Pins
on the speed controller are just such a bad idea.
The speed controller has power going to it. If any
debris fell between the pins, it could short it out. In
any event, we nestled the RageBridge deep in the
center of the robot, hopefully well away from any
With the new battery, new receiver, and new
speed controller, we had to do a fair bit of rewiring —
it was almost an entire lineup change, like what’s
happened with The Cure over the years. The smaller
battery and speed controller footprints allowed us to
move things towards the center of the robot, and the
weight savings (primarily from the battery) allowed us
to put a layer of neoprene between the armor layers
of 7075 aluminum in a bid to improve shock
We were almost ready for battle, except for an
often overlooked step ...
56 SERVO 06.2016
THE VIEW OF THE COMBAT PITS.
PREPARING FOR BATTLE.