Method and apparatus for moving a carriage assembly from an initial position to a target position

A method of moving a carriage unit from an Initial position to a target position relative to a storage medium rotating at a circumferential velocity. The method includes the steps of determining a first radial distance between the initial position and a center of said storage medium, determining a second radial distance between the target position and the center of said storage medium, determining a circumferential distance between the initial position and the target position, determining an initial circumferential velocity for said storage medium, calculating a velocity path with respect to the first radial distance, the second radial distance, circumferential distance, and the initial circumferential velocity, and moving the carriage unit from the initial position to the target position essentially on the velocity path. The speed lane is calculated so that the carriage unit will arrive in a radial and circumferential manner at the target position at essentially the same time. In addition, a target perimeter speed can be determined, the rotation of said storage medium can be changed from the initial perimeter speed to the target perimeter speed, and the velocity path is further related to the target perimeter speed.