Disc drive transducer deadbeat settle method utilizing interval correction

A method for settling a transducer on a target track on the surface of a rotating disc of a hard disc drive of the type having an actuator whereon the transducer is mounted, a power amplifier for driving the actuator to accelerate the transducer radially across the disc surface in response to a control signal and a servo system, including a servo microprocessor, for generating the control signal in relation to measured parameters indicative of at least the location of the transducer with respect to the target track, comprising the steps of:

• inputting said parameters to the servo microprocessor in each of a plurality of time intervals, wherein said time intervals are grouped into a plurality of deadbeat intervals;
• determining a deadbeat value of said control signal from said parameters in the first time interval of each deadbeat interval;
• determining an interval correction to said deadbeat value for each time interval of each deadbeat interval, comprising the steps of:
• selecting a time interval correction of zero for the first time interval of each deadbeat interval;
• and
• for each remaining time interval of the deadbeat interval, the steps of:
• determining an accepted value of the transducer velocity at the beginning of the time interval from said parameters;
• determining a projected value of the transducer velocity at the beginning of the time interval from the deadbeat value of the control signal;
• and
• determining the time interval correction in proportion to the difference between the projected value of the transducer velocity and the accepted value of the transducer velocity;
• generating the control signal in relation to the sum of the deadbeat value and the interval correction;
• and
• outputting the control signal from the servo microprocessor to the power amplifier.

A method for settling a transducer on a target track on the surface of a rotating disc of a hard disc drive of the type having an actuator whereon the transducer is mounted, a power amplifier for driving the actuator to accelerate the transducer radially across the disc surface in response to a control signal and a servo system, including a servo microprocessor, for generating the control signal in relation to measured parameters indicative of at least the location of the transducer with respect to the target track and the output of the power amplifier, comprising the steps of:

• inputting said parameters to the servo microprocessor in each of a plurality of time intervals, wherein said time intervals are grouped into a plurality of deadbeat intervals;
• determining a deadbeat value of said control signal from said parameters in the first time interval of each deadbeat interval;
• determining an interval correction to said deadbeat value for each time interval of each deadbeat interval, comprising the steps of:
• in the first time interval of each deadbeat interval the steps of:
• determining a nominal control signal value corresponding to the power amplifier output inputted to the microprocessor in said first time interval of the deadbeat interval;
• and
• determining the interval correction in relation to the difference between said deadbeat value of the control signal and said nominal control signal value;
• and
• in each remaining time interval of the deadbeat interval, the steps of:
• determining an accepted value of the transducer velocity at the beginning of the time interval from said parameters;
• determining a projected value of the transducer velocity at the beginning of the time interval from the deadbeat value of the control signal;
• determining a first time interval correction in proportion to the difference between the projected value of the transducer velocity and the accepted value of the transducer velocity;
• determining a second time interval correction in relation to the difference between said deadbeat value of the control signal and said nominal control signal value;
• and
• adding the first and second time interval corrections to obtain the interval correction for the time interval;
• generating the control signal in relation to the sum of the deadbeat value and the interval correction;
• and
• outputting the control signal from the servo microprocessor to the power amplifier.