Depending on your version of Windows, you may
or may not have to point the “plug-n-play” wizard
to the driver’s folder in the Pololu install folder.
We’ve all probably done this before, so I’m not
going to detail how that works here.
When you first start up the program, you’ll
be in the Status tab which shows all kinds of
interesting things about the motor controller and
your motor. I looked around and thought “cool!”
and immediately went to the next tab called
Input Settings. This is where I found how to tell
the 18v15 to use R/C pulses to control the motor
speed. Look at Figure 8 to see what I did to
change to R/C servo pulse control.
The only thing that I had to do on this tab
was click the R/C radio button under the Quick
Input Setup button. That handled requirement
#1 above. To handle requirement #2 (the LiPo
low battery cutoff settings), I needed to select
the Advanced Settings tab. I then set the Low
VIN shutoff to 5.8V which is about 2.9V per cell
— a value I think is very safe while still getting
the most out of the pack. This means that the
18v15 will shut down the driver if the battery voltage falls
below this value.
LiPo batteries will be unrecoverable if they discharge
below a certain voltage. This voltage differs a bit with
different manufacturers, so I’m conservative here. I also set
the High VIN cutoff at 10V — safely above the 8.4V max
voltage a two-cell LiPo pack can have. I wanted the
controller to not work if a 11.1V or higher battery was
installed; this would prevent the critter from going too fast
( 11 year old, remember?). See Figure 9 for this screen’s
data. I’m not going to explain all of the fields here; the
Pololu manual does a great job of that.
The last requirement to limit the critter
speed is handled in the Motor Settings tab; see
Figure 10. The default max speed for a motor is
3,200. I throttled this speed back to max out at
2,000. This is the limit for either forward or
backward speeds. If you want to set a different
backup speed maximum than the forward speed,
select the Asymmetric box. I left everything else
alone. Munch is now ready for critter crunching
action with a more responsive motor controller
than low-end ESCs provide. At $40, the only
thing the 18v15 lacks is the super high current
capability (usually 30-50 amps) of the R/C
commercial units. We didn’t need that kind of
current — most of our robots don’t either! I
recommend that you play around on all of the
screens while running your motor, and see all of
the knobs and buttons that Pololu provides for
this motor controller series.
I’ve never seen any motor controller with so
many configurable features as the Pololu 18v15
simple high-power motor controller. Obviously,
Figure 9. Motor Control Center; Advanced Settings tab.
“simple” means it’s simple to use because it certainly does
not lack for complex configurations.
Last Thought
Well, you’ve done it again. Read one of my columns
and hopefully been educated about something, or at least
inspired. Now get out there and get those robots running!
If you should have a problem or a question, please don’t
hesitate to drop me an email at roboto@servo
magazine.com and I’ll do my best to work on it. SV
Figure 10. Motor Control Center; Motor Settings.
SERVO 12.2012 13
