Page 186 - Designing Autonomous Mobile Robots : Inside the Mindo f an Intellegent Machine

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CHAPTER

Sensors, Navigation Agents

and Arbitration

Different environments offer different types of navigation features, and it is impor-
tant that a robot be able to adapt to these differences on the fly. There is no reason
why a robot cannot switch seamlessly from satellite navigation to lidar navigation,
or to sonar navigation, or even use multiple methods simultaneously. Even a single-
sensor system may be used in multiple ways to look for different types of features at
the same time.

Sensor types

Various sensor systems offer their own unique strengths and weaknesses. There is no
“one size fits all” sensor system. It will therefore be useful to take a very brief look at
some of the most prevalent technologies. Selecting the proper sensor systems for a
robot, positioning and orienting them appropriately, and processing the data they re-
turn are all elements of the art of autonomous robot design.

Physical paths

Physical paths are the oldest of these technologies. Many methods have been used to
provide physical path following navigation. Although this method is not usually thought
of as true navigation, some attempts have been made to integrate physical path following
as a true navigation technique. The concept was to provide a physical path that the
robot could “ride” through a feature poor area. If the robot knew the geometry of the
path, it could correct its odometry.
Commercial AGVs, automatic guided vehicles, have used almost every conceivable form of
contact and noncontact path, including rails, grooves in the floor, buried wires,
visible stripes, invisible chemical stripes, and even rows of magnets.

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