Although robot arms that spot weld our cars together have been around for some time, a new class of robots, the mobile robot, has been quietly growing in significance and ability. For several decades now, behind the scenes in research laboratories throughout the world, robots have been evolving to move automatically from place to place. Mobility enables a new capacity to interact with humans while relieving us from jobs we would rather not do anyway.

Mobile robots have recently entered the public consciousness as a result of the spectacular success of the Mars rovers, television shows such as Battlebots, and the increasingly robotic toys that are becoming popular at this time.

Mobility of a robot changes everything. The mobile robot faces a different local environment every time it moves. It has the capacity to influence, and be influenced by, a much larger neighborhood than a stationary robot. More important, the world is a dangerous place, and it often cannot be engineered to suit the limitations of the robot, so mobility raises the needed intelligence level. Successfully coping with the different demands and risks of each place and each situation is a significant challenge for even biological systems.