Using Gateways to Build a Route Map
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Doug Baker		Weh7220	 		23rdNov94


We present a simple, compact representation that allows a mobile robot to
navigate through the environment.  At the heart of the representation are
gateways, which are transition points between spaces in the environment.
We present an algorithm for detecting orthogonal gateways using sonar
sensors.  This algorithm was implemented as a state machine on a mobile
robot operating in the hallways of our laboratory.  In tests of our
implementation we guided the robot along several paths in our experimantal
environment.  Then, when told a start space and a goal space, the robot
could retraverse a route by passing through the gateways that connect the
start space with the goal space;  the route productions told the robot
which way to turn at each gateway.  In addition, this paper describes how
the decision to choose gateways as the basis for our route map
representation impacts the organization of additional levels of
representation that will allow the robot to store sensory information about
spaces and to store global information about the environment.