As an important extension of the motor capability of human being, mobile robots are now expected to implement various tasks and have become important tools in all kinds of application fields, such as manufacturing plants, warehouses, nurse/medical service, tour guider, resource or space exploration, NANO manipulation, national defence and so on. In the family of mobile robots, humanoid robots, robot pets or toys and robot assistants etc have now been becoming some new research and application trends, and more and more potential applications of mobile robots are emerging
