Fast Eigenvector Control of a Disk File Actuator
Original Publication Date: 1980-Apr-01
Included in the Prior Art Database: 2005-Feb-13
Present control systems for disk file actuators use wide-bandwidth velocity servos for track seeking. A predetermined velocity curve is generated from the position signal to allow the servo to follow its time-optimal phase-plane trajectory. An accurate tachometer or velocity-synthesis circuit is required to provide the feedback signal, thus forcing the servo to follow the curve. On arrival at track, a position-servo loop (track-following servo), designed for good DC accuracy, is switched in - hopefully, with zero initial conditions. A major problem in both control loops is the high frequency, high-Q mechanical resonance. This makes it difficult to stabilize both the position loop and the even wider bandwidth seek loop.