make them do a task like we do, then we can better
understand how we do it ourselves. What logical
underpinnings are behind whatever it is that you are doing?
I know I have certainly learned a lot about myself over the
years through my machines, and I hope that by taking on
this new and exciting journey, that you too will have the
same revelations.
Constructing Your Minion
Alright, I suppose it’s time to get to the heart of the
matter. You’ve made the plunge and bought your TankBot
kit. Great! If you don’t have one yet, go to the SERVO
webstore at http://store.servomagazine.com and get
one. While it may look intimidating at first, I promise that it
really isn’t as hard as it seems.
At least for me, building a good base for your robot is
always one of the most challenging tasks. Many hobbyists
will scavenge parts off of broken electronics, or use some
old “junk” from around the house to build their platforms.
While this may be fine and dandy for most, if you are just
starting off in this hobby, you probably don’t have a closet
full of broken stuff to start pulling parts from. So, just
some advice, start collecting now. You never know,
grandma’s broken vacuum could be the beginnings of your
first laser beam cannon!
The TankBot kit — first and foremost — provides you
with a good clean base to start from. All the pieces are
prefabricated and nearly all the parts you would need are
included in the kit. The “body panels” themselves are made
from a dense plastic foam board which is great because it’s
nonconductive. One of the first rules you’ll learn about
robotics is that conductive surfaces can often be your
enemy if you don’t account for them. In our case, we can
pretty much mount our electronics anywhere we please
without fear of shorting something out.
For locomotion, the kit provides two modified
servomotors. Why modified? Well, most servos travel over
a given angular distance, providing them with a great
capability to position themselves precisely wherever
commanded. This range varies depending on the
manufacturer, but on average they can move is about 310
degrees. However, we need a constant rotational motion in
order to propel our tank. In this case, the servo gearing
and electronics can be modified in order to provide a full
360 degrees of motion, allowing us to provide an input that
continually drives the servo in one direction. Luckily, the
hard part is already done for you in this kit, and no further
modification to the servos is needed.
Obviously, with our base being called a TankBot it leads
you to assume that we are going to be using a belted tread
as our drive mechanism. For the beginner, this really is an
ideal set-up. Treads are very forgiving when it comes to
navigation and overall control. While we are all used to the
concept of wheels and how they steer, there really is an
entire extra layer of complexity that goes with them that
you may not initially think about. Not only do you need one
set of controls to drive the robot forward and backward,
you then need some kind of mechanical linkages along with
a completely separate control system for steering. A typical
wheeled design would also require a higher level of
complexity in programming your future robot. In any type
of automated sequence, you would have to add allowances
for turning radius, rate of turn, speed variation, etc. With all
that said, don’t let me discourage you from ever using a
wheeled design. They are generally very easy to scavenge
off an old RC car, and are prominently available at local
hobby shops.
I’m not going to get into detailed assembly steps for
the kit as the instructions provided with it do a really great
job of showing how to put it together. Honestly, the
TankBot takes about a half hour to put together, so it won’t
be an all day affair. If you can thread a nut onto a bolt, you
pretty much have the prerequisite skills covered. There are,
however, a few areas that I’d like to provide some tips on
to perhaps save you some headaches down the line.
First, do not over-tighten the fastening hardware. While
your first instinct may be to really crank those suckers
down, you will actually be doing more harm than good.
Too much pressure could deform the body panels of your
TankBot, leading not only to an unsightly and sloppy
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