make a great bot for the duct crawler. I made the main base
out of 1/8” and 1/4” expanded PVC. Expanded PVC is great
to work with because you can tool it with normal wood
working tools. You can even score it with a razor knife and
break it in a pinch. Expanded PVC can usually be purchased
at a local sign shop.
In my case, the sign shop just gave me their scraps. If you
don’t have access to expanded PVC, you can also use fiber
board, wood, or Plexiglass.
In the second attempt, I used two small gear motors,
connected in parallel on each side of the bot. In order to
make the bot as compact as possible, I built two motor
assemblies, as shown in Figure 3.
The motor assemblies were just two pieces of 5-1/2” x
1-1/2” x 1/4” expanded PVC with two of the gear motors
sandwiched in between them. I used double-sided carpet
tape to hold the gear motors in place while I positioned the
PVC. Everything is really held in place by 3/4” standoffs and
#4 machine screws. Figure 4 shows how each of the motor
assemblies was mounted on one side of a 5-1/2” x 6-1/2” x
1/8” piece of expanded PVC.
Figure 5 shows how I attached all of the wires to a
female header so they could be plugged into the Ares board.
I used small, 1/4” standoffs for mounting the Ares. The other
standoffs in that figure are used to hold the main six cell
battery in place.
Figure 6 shows the Ares board mounted securely to the
standoffs, and nestled between the “drive pods”.
The camera was attached directly to a round horn
connected to a servo mounted on top of one of the motor
assemblies. The servo is controlled by the Ares board and
allows me to move the camera up or down.
By spinning the bot, I can view just about any angle. For
lighting, I attached two 6 volt incandescent flash light bulbs
directly to the switched Vin on the Ares board. These bulbs
mounted on two holders, which can both be purchased
One thing I discovered with the first attempt was that
the 9 volt battery would run out of power very quickly when
connected to the camera. I could not take the chance of this
happening while the bot was deep inside the duct work, so
I used a larger, 9. 6 volt NiCad battery pack on this attempt.
Figure 8 shows the red battery pack strapped to one side of
The Ares board has a provision for a small IR module.
This makes hook-up very simple. Complete directions on
attaching the components discussed in this article can be
found in the Ares manual.
Dios Operational Program
The Dios program is straightforward. It makes a call to
the built-in IRread function and branches to a section in the
code to handle the particular switch.
Each switch has three states, so a branch command
is used to jump to the various handler code for that switch
Transmitter Commands handled:
Switch 1: Control Motor 1 Forward/Stop/Reverse
Switch 2: Control Motor 2 Forward/Stop/Reverse
Switch 3: Control Bot Speed
Switch 4: Control Camera Angle
botpower = 190
camerapos = 7500
Figure 1 — The version 1
10 SERVO 07.2004
Figure 2 — The duct flow valve.
Figure 3 — The motor modules.