support the motor, so it was done with
additional framework in the robot. This was
installed in my 30 pound combat robot “Trigger
Happy.” After two fights, the motor showed
signs of coming loose from the transmission.
The second edition did a much better job
supporting. Take a look at Photos 2 and 3. SV
Photo 1: Version 1 motor mount/
shaft support.
Photo 2: Version 2 supports the motor.
Photo 3: De Walt 18V motors mounted
in the frame of a 30 pound robot.
2.
3.
MAN UFACTUR IN G:
Cl sed Loop
Lifter S lutions
● by Don Hebert
Ihave worked with embedded microcontrollers for many years. So, when I began building
combat robots in 2001, I was
tempted to automate something. A
lifter powered by an electrical motor
seemed doable. I spent many hours
solving mechanical and electronic
issues and made a Victor883 stop
automatically when reaching the top
and bottom of the allowable lifter
stroke. Those two PIC eight-pin
microcontrollers I programmed in
2002 are still in use; I move them
from one project to the next all the
time. Since then, I have tried other
microcontroller products and off-the-shelf preprogrammed devices to see
if they were satisfactory. I will
describe the various solutions I have
employed.
Basics of the Signals
that Come From
the Receiver
The radio receiver (Rx) outputs a
pulse length proportional to the
transmitter stick position. For a
rudder, full left is one millisecond
(ms), middle is 1.5 ms, full right is
2 ms. The actual value can be
modified by travel adjustments in
the transmitter. The stick direction
that is 1 ms can be changed by
reversing that channel in the
transmitter. The Victor 883 from
Innovation First accepts this signal
and can drive 60 amps. The lifter
motor is a Harbor Freight 18V drill
motor.
SERVO 02.2011 27
