1.	Hardware
1.1.1   Robot Base
The base will be a Lynxmotion CarpetRover 6" x 6" mobile 
robot platform powered by a pair of Hitec HS-300B servos 
modified for continuous rotation. 
  See document:
  See document:  servos.html

1.1.2   Microcontrollers 
A Lynxmotion "First-Step" Basic Stamp I controller will be used 
exclusively to run the drive servos. 
  See document:  lynxbs1.gif 
A Parallax Basic Stamp II mounted on a BS2-IC Carrier Board 
will be used for reading sensors and navigating the maze. 
  See document:  bs2csche.gif
  See document:  bs2cb.gif
  See document:  stamp2.gif
  See document:  robotwir.txt

1.2	Sensors
1.2.1   IR Object Detector
An Infra-Red Object Detection System was designed and fabricated 
on 03-11-99.  The IR receiver module (RadioShack #276-137B) 
output was too susceptable to false triggering due to ambient 
lighting so it's output was integrated and fed into a 
comparator with an adjustable threshold reference voltage. 
A threshold was picked to eliminate false triggering. 
IR attenuation filters (slips,of paper) will be taped over each 
of the four receivers in varying thicknesses to equalize the 
sensitivity of each module so they all trigger at approximately 
5 inches distance from the maze wall. 
  See document:  irsensor.gif
A 74LS156 1 to 4 line Multiplexor was added to route 
the 40 KHz clock to 1 of 4 IR LED's using only 
2 select lines.  A 74LS153 4 to 1 line Demux. was added 
to select 1 of 4 IR Receiver Modules and route it's output 
to the integrator circuit using the same 2 select lines.  
See the Prototype section for a more detailed schematic. 

1.2.2   Flame Detector 
During a period of indecisiveness over whether to buy a 
commercially made flame sensor, such as Acroname's 
IR flame sensor or Hammatsu's Ultraviolet flame sensor, 
  See document:
  See document:
I experimented with some IR phototransistors to see if it 
would be feasible to design our own.  The first tried was 
a Radio Shack part.  Unfortunately the ambient overhead 
flourescent lighting had more effect than a candle flame 
on this device.  It was evident that both optical filtering 
and focusing would be required to make this feasible.  
I ordered every photo device in the Electronic Goldmine 
catalog along with some mirrored flashlight type reflectors 
and some Kodak 87C IR filter material.  I also salvaged the 
IR lens material out of an old passive IR motion detector.  

1.2.3   Wheel Optical Encoders 
I purchased some Reflective IR Sensor/Emitter units from 
the Electronic Goldmine (cat.# G8669) that looked ideal for 
this application.  These are an IR phototransistor and 
IR LED paired together in a black plastic case, such that 
reflected IR light from a close proximity object will cause 
the phototransistor to conduct.  These can be mounted on 
the underside of the Lynxmotion Carpetrover robot base, 
facing the inside surface of each tire.  Circular paper 
disks colored with alternating flat black and flat white 
color bands can be glued to each tires inside surface.  
Once optimally positioned, the phototransistors should 
output pulses marking distance traveled by the spinning 
tires.  Here is the related calculation: 
Tire Diameter = 2.875" 
Tire Circumference = PI * D = 3.14159 * 2.875" = 9.03207" 
Thus, Distance traveled = 9.03207 inches/revolution. 
Resolution of this system is determined by the number of 
white color bands on the disk.  Thus for a disk with 
8 white color bands seperated by 8 non-reflective black 
color bands, the resolution is 9.03207" / 8  or 
1.129" per pulse.  This is provided the Basic Stamp II 
controller can count every pulse without missing any. 

2.	Software
2.1	Robot Base
A 3 bit bus will be used to direct 5 cardinal motions: 
Hold, Forward, Back, Right, and Left. 
A flowchart was completed on 02-21-99, and the 
PBasic program was written and debugged on 02-22-99.
This would become the basis for motion control of 
our robot via the Basic Stamp I controller. 

2.1.1	Flowchart
  See document:  lynxflow.gif
2.1.2	Sourcecode
  See document:  lynx.bas
2.2	Sensors

See the next section "Prototyping" for info. on construction 
and further refinements.

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