A method for improved positioning of wander on a hard disk

摘要

A method for settling a transducer (18) of a hard disc drive (10) on a target track (30) on a rotating disc (12) of the disc drive at the end of a seek to the target track in a determined time period. The time period is divided into two deadbeat intervals (58, 60), each of which is divided into a plurality of time intervals in each of which the location of the transducer with respect to the target track is measured (80) and an accepted value of transducer velocity is measured (82) or determined from successive locations of the transducer. In the first time interval of each deadbeat interval, a deadbeat value of a control signal is determined (88) on the basis of ideal deadbeat settle of the transducer to the target track and outputted to a power amplifier (36) that drives the actuator (40) on which the transducer is mounted for radial movement of the transducer across the disc. In subsequent intervals of each deadbeat interval, an interval correction (102), determined in relation to the difference between a projected velocity determined from the deadbeat value of the control signal and the accepted velocity of the transducer, is added to the deadbeat value and outputted (94) to the power amplifier. A second interval correction (132, 136, 138) can be added to the deadbeat value to correct for a long power amplifier time constant.