SERVO 09.2015 35
allowed the screw to be screwed tight
to the nutstrip (thus removing the
need for threadlock). The screws had
about one inch of threads; I cut the
extra length of the screws off with a
Dremel tool.
Final Touches
The motor shafts are about an
inch longer than they need to be for
this application; that extra length
could make the shaft more vulnerable
to a spinning weapon, so I trimmed
the shafts with my Dremel tool to be
flush with the wheel hub.
The base plate still had open
holes where the spinner weapon kit
power key would go, and a few gaps
in the wheel well. After a few fights,
the arena can become littered with
dust and debris which I would rather
not have inside my robot. So, I
covered the holes and gaps with
Gorilla tape (similar to duck tape but
stronger and hairier).
With all modifications done and
the robot completely assembled, it
weighed in at 15. 50 oz. I tested the
robot on a concrete floor and found it
to be quick and responsive. It drove
very straight for a two-wheeled robot
(which tend to pull to one side), and
the flipper arm had enough power to
pick up a 1 lb object. However, the
shape of the steel "scoop" that came
with the lifter kit made it hard to get
under my test dummy to get a good
flip in. The robot was able to self-right
very easily from any orientation.
Combat Report
Viper Fighter MK-2a's first trial
by fire was at Clash of the Bots
2015. The first fight was against
Super Orange Glow by Team
Browns Mountain Lab from
Greeneville, TN. This robot featured
a small vertical spinning disk and a
four-wheel drive system. Viper
dominated this match, consistently
out-running and out-maneuvering
the much slower Super Orange
Glow. Viper was able to get in
several lifts and a few flips, plus also
push the other bot to the wall a few
times. In contrast, Super Orange
Glow's disk did only superficial
damage.
Viper Fighter's second opponent
was Klazo by Near Chaos Robotics
from Norcross, GA. Klazo featured a
powerful spinning drum weapon and
a two-wheel drive system. At the start
of the match, Viper charged Klazo,
met her head on, and tried to get a
flip in, but did not get the scoop far
enough under Klazo for an effective
lift. Klazo quickly came back and
clipped Viper's left side with her drum
and easily took off a wheel. Viper
tried to stay in the fight by "crab-walking" across the arena and got in
one partial lift before Klazo took off
the other wheel and ended the match
in one minute.
Total damage to Viper: two
broken motor shafts; one lifter arm
was bent and cracked at the cross bar
joint; the right front corner of the
chassis was bent upward; and there
were several deep gouges in the front
polycarbonate plate.
Klazo went on to take 2nd place,
losing only to teammate, Algos. I
chose to forfeit Viper's next match so I
could focus on repairing my other
robot.
Conclusions
Upgrading the drive to 11.1V
dramatically improves driving
performance and helps get the flipper
in position. The XQP-4220 servo at
11.1V performs very close to the HXT
12 kg at 9V. However, it should be
noted the HXT 12 kg is only rated for
7.4V, whereas the XQP-4220 is rated
for 11.1V (which should make the
XQP-4220 more reliable).
Viper took several major hits from
Klazo's drum but suffered no internal
damage. The servo was very well
protected. Over all, Viper MK-2a
preformed much better than Viper
MK-1. For the next version (MK-2b), I
would like to protect the motor shafts
from side hits and modify the lifter
scoop and arm in order to get under
the opponent better. SV
Viper Fighter MK- 2 complete.
Viper Fighter MK- 2 vs. Super Orange
Glow at Clash of the Bots 2015.
Viper Fighter MK- 2 after fight with Klazo
at Clash of the Bots 2015.
Viper Fighter MK- 2 vs. Super Orange
Glow at Clash of the Bots 2015.