Robots are composed of several systems working together: the controller is the robot's brain, which controls its movements; the body is the robot's physical appearance related to the job it performs; mobility, or how the robot moves, depends on the job it performs (for example, a robot uses propellers and rudders in the water, and legs or wheels on land); power is used to fuel the robot (electric solar cells are one example, such as the solar-powered robots described here); sensors provide signals to give robots a perceptual understanding of their environment so they can alter their behavior based on that information; and tools are unique to the task the robot performs. Just as robots are made of several systems, the field of AI requires a collaboration of many different disciplines to be successful. Engineering is clearly useful, but I know people who have a background in biology, psychology, physics, and computer science. What's most important is a willingness to learn a lot of new things from a variety of disciplines.