In Figure 12, the second power pack is shown upside
down (and reversed) to minimize the overall profile of the
robot. In Figure 13, it is upright, and the terminal blocks
are forward toward the power connections on the project
board. I’m still not sure if I like these options, so my next
revision may see both supplies moved to the lower deck.
For now, this will work.
There are some issues in the final build on this version
of the Manta Ray DXF file. No provisions were made for a
power switch. We also have two isolated power supplies
that should be switched on at the same time. I will look for
a DPST or DPDT switch that can mount easily to the Manta
Ray upper deck, and have a mounting hole added to the
The motor driver board has extremely small mounting
holes, and I surprisingly did not have mounting hardware
for it. You could use double-sided sticky tape or Velcro™to
attach it to the lower deck or not, but I will be definitely be
actively seeking hardware and will add proper mounting
holes for that board, as well. In this build, I secured it to
one of the rear standoffs.
The wire hole in the upper deck will be moved back so
that wires can come up from behind the control board. I
will also be adding slots along the sides of the control
board to allow wires to come up along there, as well. These
changes should allow stacking of the power packs on the
lower deck and minimize the overall profile of the robot.
If you compare Part 1 with Part 2, you may have
noticed I changed some hardware, such as switching to
lower-profile standoffs. This was a personal taste thing and
isn’t necessary for function. The only part that you need to
be careful on is if you do stack the power packs.
If (and when) I make that change, I will post an update
about it to the project page on my website (see
Resources). Please note: No changes were made to the
DXF file between Part 1 and Part 2 of this article.
I didn’t get into the details of the control wires
between the control board and the motor driver board.
Because there was no final mounting option made for this
board, I wasn’t sure if the leads I used would still reach
after mounting holes have been finalized. For this revision, I
used 200 mm F-F jumper wires (which come in a 20-pack
The three-pin cables aren’t as useful here as they are
on the PING))) sensors because you don’t need ground and
power for every signal. So, in this case, these individual
wires work out better; you can use them for the sensors if
you prefer. You might want to use some heat shrink tubing
or some other cable management option to keep them
By the time you read this, you should be able to find
the source code and schematic also on the project page of
my website. The reason I did not include the schematic here
is that it is evolving with the code. Any change I make to an
I/O pin would cause a revision to the schematic.
What I am going to do is include a schematic for each
source code download. That way, as I make changes, add
sensors, etc., you will have the proper diagrams for the
electrical changes made. I will show the summary of
changes for each version.
The examples that will be available for this issue of
SERVO are roaming with PING))) sensors, and R/C control
using these sensors to avoid collision. More examples will
come out over time as things evolve.
Once I have created examples for several versions of
this robot, look for a follow-up article here with a picture of
each robot, what it does, the schematic, and the source
code for it.
Now, jump in feet first and start your Manta Ray build!
74 SERVO 07.2014
Figure 13. Mounting the second power pack
normally over the control board.
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