Part 6: An Arm for Megabot
by Michael Simpson
Last month, we used Wi-Fi to control Megabot. One
of the problems I had was maneuvering the robot in
close quarters. The laptop's built-in webcam worked
but it just did not give a good view of what was going on
around the robot. This month, we will add an external
webcam to a fully articulated robot arm. We then will add
buttons on our desktop controller program to allow us to
control this arm.
Step 1 - Add a Second Deck
There is just enough room to mount an arm in front
of the laptop, but it's a real tight fit. I had always planned
on adding a second deck to the base, so now it's time. It
will give us plenty of room to add more components and
manipulators later.
I wanted to elevate the platform about 1-1/2" above
the cradle. This will allow me easier access to the laptop
and give me room to mount things on the bottom of the
upper platform. To do this, I simply cut two more pieces of
wood at 14" x 3" and attach them to the two sides of the
cradle as shown in Figure 2. You only need a single wood
screw on each end to hold it in place. Just make sure it
sticks up 1-1/2" on both ends.
FIGURE 2.
The upper base can be made from any material. You
can use 1/4" or 1/8" stock cut to the same diameter as the
lower platform. In my case, I used some 1/4" plywood I
picked up from my local home center. You don't have to
purchase these in full sheets. The one I purchased came in
a 2' x 4' section and only cost me about $6.
To cut out the upper base, I removed the cradle and
foam from the edge and just traced it. You can also use the
procedure I covered in Part 3. I used a handheld jig saw to
cut out the platform.
To assemble the base, I first placed the upper platform
FIGURE 1.
Megabot with
his arm.
SERVO 03.2009
57
