Champobot IO structure :

All three inputs have both touch and light sensors connected to each. 
However, these are all 'read' as light sensors.
A touch sensor used this way will return a value of 100 when pressed. 
The down facing light sensors show a range of approx. 45-55 with that range
being skewed +-5 depending on the particular light sensor used.


Input 1 : left front downfacing light sensor for line detection
          left rear leg touch sensor
          right rear leg touch sensor

Input 2 : modified* light sensor in mouth for 'food' detection ('food' ocludes light to sensor)
          touch sensor positioned for upper jaw motion limit detection

Input 3 : right front downfacing light sensor for line detection 
          left front leg touch sensor
          right front leg touch sensor

Output A : motor driving left track 

Output B : motor driving upper jaw

Outout C : motor driving right track 

* The red LED was removed and replaced with two 1n914 diodes in series. This keeps the 
light input to output value similar by providing a similar electrical bias and yet 
extends the sensitivity on the low end.
Also, the phototransistor has been encased in black heat shrink tubing. This was neccessary
to help keep direct sunlight from being sensed through the side walls of the blue case.



Programmed behavior :

1. The champsosaur will follow the 'river' by when initially either set on the river 
   or pointed in a direction that will cross it.
2. It then 'swims' along the river by using the downward facing light sensors to bounce 
   off the edges of the line. This gives a zig-zag forward motion of swimming which is 
   further assisted by the bends in the line.
3. It stops when it gets to the end of the river, opens it's mouth, makes the ascending 
   notes sound, and waits to be fed.
4. Having been fed, it will turn around and 'swim' down the river to the other end where 
   it will stop, open it's mouth, make the descending notes sound, and wait for the food 
   to be removed.
5. After the 'food' has been removed It will turn around and 'swim' back to the other end 
   of the 'river' to be fed again and continue this food-fetching cycle until turned off. 

A few extra behaviors are :

1. While there is no 'food' in it's mouth or when it is not waiting for food, the champosaur 
   will chomp it's teeth.
2. If you bump either of the rear legs forward while it is 'river following' it will turn around 
   to 'see' what bothered it, beep a few times, then turn again and continue the way it had been 
   going.
3. If you bump either of the front legs backward while it is 'river following' it will
   expect to be 'fed' or expect 'food' to be removed from it's mouth. It will then turn around 
   and go the other way.