a little too small. This may be remedied in the future, but
for now — as long as I don’t roll it in a creek or let it go
careening into a lake or pool — I should be fine.
The final touch was mounting the GoPro to the front.
With that, it was time to take it out.
Testing the Mantis took a couple of forms. First, I ran it
around the neighborhood streets to get a feel for the
handling and overall performance on flat ground. As
expected, the 12V motors performed excellently with the
11.1V Li-Po battery. Acceleration was good and the torque
from the planetary gears had no problems tackling any of
the obstacles I put it up against. In fact, the wheels lost
traction long before there was any issue with the motors
There were a couple of times when the motors had a
problem accelerating out of an obstacle, but once enough
throttle was added it would power itself right through.
However, the motors used with this kit are a known. I’ve
used them with the Nomad and a couple other projects.
The real test was the chassis frame and suspension. In
my little suburban trials, the sprung six-wheel suspension
handled curbs and grass with no problem. Some
adjustment was made to the front and rear springs to keep
the chassis itself level while moving. When power was
applied to the motors, the entire chassis wanted to lean
backwards. This was not desirable when filming, so I
increased the rear shocks and decreased the front. Now, it
leans forward while at rest and is more or less level while
traveling. Depending on future applications, I may add a
pan-tilt mechanism for the camera. For these trials,
however, a forward facing mount was sufficient and I
wanted to keep it level during travel.
To further test the performance of the Mantis, I took it
to a community park with plenty of nature trails and a
couple creeks. Of course, with as little rain as we’ve had in
the past few months, the creeks were either dry or
stagnant. However, the banks were still steep, and the
terrain was varied and dusty.
On the trail, the operation was smooth. Off the trail, it
seemed unstoppable. Well, that is until “it” managed to get
itself caught on a fallen branch. The stems got themselves
hooked underneath the chassis on the motors, between the
suspension arms, and the springs. This was not a big deal,
but did take some work on the controls to free the bot, and
some picking of stems and leaves out of joints later. After
driving it through tall grass, I had to spend some time
cutting grass from the wheel hubs and shaft adapters.
All of this is expected when running a robot off-road —
where other robots fear to tread. None of the issues faced
deterred the Mantis from doing exactly what it was told to
58 SERVO 11.2015
The RoboClaw motor controller with the RC receiver
packed nice and tight in the protective box.
Mantis with the battery and electronics mounted
with zip ties.
Can't hit the trails without