High speed positioner control strategy and application

Modern high-performance 5.25-in. hard disk drives are characterized by high capacity, high data rate, short access time, and (nevertheless) low costs. In order to fulfil such different requirements, particularly average positing times below 16 ms, new positioner control techniques are necessary. Digital control became feasible in recent years because of the availability of highly integrated digital and linear circuits such as signal processors and A/D and D/A converters. The advantages of a digital control system are explained, and a mathematical description is given. The different demands in the acceleration, constant-velocity, and deceleration phases are described. Experimental results of the Megafile 5000 realization are shown. Digital control also allows an adaptation to an individual disk-drive mechanism