Servomechanism with adjustable predictor filter

A method for determining parameters of a track-following servomechanism for a tape drive system having a proportional-integral-derivative (PID) compensator, a Kalman filter, and a linear quadratic Gaussian (LQG) controller, the method comprising:

• identifying a range of tape velocities;
• identifying a process noise standard deviation from a corresponding lateral position output for all velocities within the range;
• identifying a measurement noise standard deviation from a corresponding lateral position output for all velocities within the range;
• identifying weighted norms that characterize a deviation of an overall closed-loop response from a desired transfer characteristic, a contribution of process noise to a lateral position signal, and a contribution of measurement noise to the lateral position signal;
• for a given velocity above a threshold velocity, determining parameters for a proportional-integral-derivative (PID) compensator that minimize a sum of the weighted norms;
• based on a tape velocity-dependent delay τ(v), the process noise standard deviation, and the measurement noise standard deviation, determining parameters for a Kalman filter for each tape velocity within a predetermined set of tape velocities;
• and
• based on the tape velocity-dependent delay τ(v), determining parameters for a linear quadratic Gaussian (LQG) controller for each tape velocity within a predetermined set of tape velocities.