Disk storage apparatus and method for servo controlling

A method of servo controlling in a disk storage apparatus including an internal model configured to follow a detected position of a head to calculate an estimated current position which is a position error with respect to a target position of the head, and performing head positioning control, the method comprising:

• determining whether or not to carry out servo interrupt processing;
• holding a number of negative results of the determination;
• and
• correcting a state of the internal model based on the number of negative results of the determination if the result of the determination is affirmative.

A data processing device comprising:

• an interrupt controller configured to determine whether or not to allow a control system to carry out interrupt processing every sampling point of time and to hold a number of negative results of the determination;
• and
• a processor comprising an internal model configured to follow an output value for a control target to calculate an estimated input value which is an error with respect to a target value,
• wherein the processor is configured to correct a state of the internal model based on the number of negative results of the determination and perform a calculation for the control system based on a result of a calculation of the internal model, if the result of the determination by the interrupt controller is affirmative.