Prototype
  See document:  ffc8.jpg
  See document:  ffc21.jpg

1.	Hardware
1.1	Robot Base
As mentioned in the Analysis section, the base is 6" x 6" 
Lynxmotion Carpetrover mobile platform powered by a pair 
of Hitec HS-300B servos modified for continuous rotation. 
One point missed by all the servo modifiacation procedures is 
that you must transpose the motor leads inside the Left servo 
for it to be programmable in the same way as the right motor. 
This is because they are mounted transversely to each other. 
Stan Kusmider designed a second 6" x 6" platform and custom 
5 11/16" threaded stand-offs to support it above the base, 
as a "second story addition" to our robot.  This was needed 
space for mounting our homebrew flame-extinguishing fan at 
approximately 7 3/4" above the ground (candlestick height) 
and ample room for the Parallax Basic Stamp II carrier board 
extra batteries, flame sensors, and an electronic compass.  
The Lynxmotion "First-Step" Basic Stamp I controller, the 
Sensor Board, the four Object detection IR Receivers, 
along with wheel encoders, batteries, and servos took up 
all available space on the lower deck.  Whenever any 
mechanical mounting method was needed, Stan took care of it. 

1.2	Sensors
1.2.1   Flame Detector 
The photo devices from the Electronic Goldmine arrived 
mid-March, about 1 month from the Trinity Fire-Fighting 
Robot Contest date.  With little time to spare, they were 
experimentally tested in the Ward College lab, and within a 
few days, it was determined one set of devices performed 
better than all the rest in our IR-noisy environment 
(energy-saving electronic ballast flourescent lighting). 
These were unmarked Honeywell IR phototransistors in a 
tiny black rectangular package. The Electronic Goldmine 
part# for these is G9412.  Even with a reasonably high 
value collector resistor of 27K,  the overhead lighting did 
not even begin to turn on the device.  Yet a small flame at 
a foot or more distance easily saturated the collector.  
The only problem was the omni-directional pickup pattern: 
it would pick up a flame in almost any direction, making it 
impossible to determine what direction it was coming from. 
Some experimentation with flashlight type silvered reflectors 
was tried.  This idea was discarded when it became apparent 
the increased optical gain was too much, and had higher 
gain at visible 500-750 nM. light wavelengths than at the 
desired 900-1000 nM. Infra-Red region.  While scouring the 
junkboxes, a better solution for a narrow aperture housing 
was seen:  Black plastic Waldom WN-10 Wire Connectors for 
twist splicing AWG-10 house wiring.  After removing the 
springs from several of these, 2 small holes were drilled to 
allow the phototransistor leads to exit, and the devices 
were glued about halfway into these "housings".  
Three were mounted on the underside of the robot's upper 
deck at approximately 7.5" height above ground using 
tie-wraps and adhesive backed clamps, facing to the front, 
right, and left sides at a slight downtilt angle.  
Rather than run the phototransistor outputs directly into 
the Basic Stamp II, it was decided to add comparator circuitry 
with a small amount of hysteresis.  A threshold reference of 
1/2 Vcc would be employed, which should reduce false triggering. 
  See document:  robot2.gif
   
1.2.2   Wheel Optical Encoders 
The circular paper disks colored with 8 sets of alternating 
flat black and flat white color bands were printed on a laser 
printer and glued to each tires inside surface.  


1.2.3   Sensor Board 
The board containing the IR Object detector circuitry will now 
be called the "Sensor Board".  It was removed from the robot and 
additional circuitry for controlling the flame sensors was added. 
This included "ambient noise" reduction by processing each signal 
through a comparator stage.  A spare 4-1 multiplexor was used to 
"steer" any flame detector output to a single pin on the Basic 
Stamp II (P1).  Also, this circuit was wired such that the selected 
flame sensor would always be OPPOSITE the selected object IR sensor.
This is so our own Object detector IR LEDS would not generate 
interference to a flame sensor on the same side of the robot.
A 5V coil reed relay in a 14 pin DIP was added to allow the Basic 
Stamp II to control turning the Fan on or off via I/O pin P11.  
Here is the complete schematic of the robot's Sensor Board: 
  See document:  robot.gif
If you'd like to print the schematic, here it is in 2 parts: 
  See document:  robot1.gif
  See document:  robot2.gif
Here is the complete Circuit Board layout: 
  See document:  robot4.gif
Here is the Bill of Materials: 
  See document:  robot.bom
Here is the Robot BS2 Wirelist: 
  See document:  robotwir.txt



1.2.4   Electronic Compass 
An Dinsmore 1490 electronic compass sensor was wired on a small 
circuit board.  It has 4 active low outputs related to compass 
points N E S W with some overlap so an additional 4 directions 
NE SE SW NW may be intpolated.  The 4 open collector outputs 
were pulled up to +5v by 22K pullup resistors and routed to the 
Basic Stamp II I/O pins P4,P5,P6,P7. 
  See document:  robot3.gif

View the next section "Testing" to see how this all worked out. 

Back to Robot Main Page