Reflected Signal Problem

[Joyce Poon <poonj@ecf.utoronto.ca>]

I really want to solve the problem of reflected signals.  We don't want to
be picking up the signal on top our robot thinking it's the enemy, and end
up chasing ourselves.  And you just know that Malone is going to put
reflective surfaces. 

Possible Solution(?): we can put a set of IR emitter-detector at the
bumper level of the robot (the beacon IR detector will be near the top of
the robot -- see specs for beacon restrictions), and if the bumper IR
detector can pick up a signal, then we know that we are looking directly
at a reflective surface.  I suppose we can mount 5-6 (maybe less?) of
these IR emitter-detector pairs so that we can also detect reflective
surfaces that are at an angle to our robot (we can figure out the location
of these surfaces by noting that the reflected light is at the same angle
as incident light from the normal). 

To simplify the algorithm (ie. we are simply noting whether we are looking
at a reflective surface as supposed to gathering info about our
environment), if the bumper IR sensors are placed at the exact same angles
as the beacon IR sensors, then we know we are looking at a reflected
signal when the 2 corresponding sensors are both "on". 

The above solution assumes that the surface is "consistent" i.e. the
surface is reflective at the bottom <=> it's reflective at the top. 

A problem with this solution is the issue of protecting these sensors
(since they are at the bumper level of the robot).  We don't want to
damage them but they are at the most vulnerable location.  We might be
able to nestle them between the foam padding.  I wonder whether putting a
sheet of plexiglass in front of the sensors will hinder its sensory
capability. 

What do you think? Any ideas on a simpler solution? 

Joyce :)