HEAD POSITIONING DEVICE, HEAD POSITIONING CONTROL METHOD, HEAD POSITIONING CONTROL PROGRAM, RECORDING MEDIUM RECORDED WITH HEAD POSITIONING CONTROL PROGRAM AND DISK APPARATUS USING THEM

PROBLEM TO BE SOLVED: To realize a head positioning control means for a disk apparatus using a dual actuator by which the positioning control of a head is attained by a stable operation even when being affected by frictional force based on static friction of a coarse adjustment actuator. SOLUTION: The head positioning control means is provided with a fine adjustment control part 162 to control positioning of the head by controlling displacement of a fine adjustment actuator 52 based on a positional error signal and a coarse adjustment control part 161 to control the positioning of the head by a relative displacement signal corresponding to the displacement quantity of the fine adjustment actuator 52, the coarse adjustment control part 161 has a nonlinear transformer 18 having nonlinear characteristics by which the relative displacement signal is amplified with a larger gain in comparison with the case when amplitude of the relative displacement signal is large when the amplitude is small and performs the positioning of the head by the coarse adjustment actuator 51 based on its transformed output signal.