Abstract
In Hard disk drives (HDD), a mode-switching control (MSC) method has been widely applied as a motion controller. This MSC is defined that there are several servo modes and each servo mode is switched from one to another during a servo action. The design points are how to set initial values of controller at switching and how to define the switching condition. The MSC has been studied since 1970s in HDD industry, and an initial value compensation (IVC) method has been developed to determine appropriate initializing of controller and switching conditions in 1990s. The MSC with IVC has been extended to consider the suppression of mechanical resonance excitation and the reduction of acoustic noise during seek-settling. In order to enhance both fast movement and precise positioning accuracy capabilities, this type of MSC should be discussed and re-designed in the frame of hybrid system theory.
