Positioning systems in general have their most basic form, and also the most complex, in the human being. The brain serves as the summing network that accepts the command for a desired motion or position, the musculatory system serves as the power source or prime mover to cause motion to take place, and the sensory system, such as the eyes, determines the present position. In general, these three things—the brain, the muscles, and the eyes—are analogues to the three basic parts of any positioning system
