32 SERVO 02.2018
commands at the same time. I
contemplated adding a second TX,
but that was going to be
cumbersome. Carrying two radios for
I decided to make a “Mode”
function in the software, connected
to one of the RX binary switches. This
way, the same proportional sticks
would deal with either the wheels or
the arm based on the Mode
selection. I realized that I won’t ever
drive and grab things with the claw
at the same time.
With my daughter Emma’s help,
we took apart all the hubs, cleaned
them, and lubricated them. Andros
runs on brass bearings (not wheel
bearings), in order to deal with heavy
loads. From existing pictures, I
noticed the newer generations of this
model have optional rubber wheels,
so the unit (280 lbs) doesn’t wear
out the tracks. This robot didn’t
include that, but I wanted the option.
Enter Home Depot’s wheelbarrow
wheels at $25 a piece.
That was the easy part.
Attaching them to the hub was a
As a spacer, we used a waterjet
cut 2” thick piece of acetal on each
wheel. We then made a connecting
plate (1/4” aluminum) from the
Andros’ hub to the wheel; each being
screwed in to the hub by 20 10-24”
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The arm has been assembled back,
but there were still issues to work on
inside the main box. The robot opens
like a box for access inside; the arm is
resting on the table. This part of the
body contains a 20 AH battery, four
motors, a circuit breaker panel, DC
motor control, and a few relays.
Robot on its “toes” and the upper
electronics box open. The two Teensy
2.5s, the RC receiver, the telemetry
unit, and antennas reside here. An
analog ammeter has been
temporarily attached on the side to
monitor power consumption (almost
30A when the robot climbs stairs).