A disk drive control method and apparatus. In particular, a torque
constant correction method and apparatus in a disk drive using a multiple
sinusoidal seek servo scheme. The torque constant correction method
includes: performing a test seek routine for torque constant correction
by using a multiple sinusoidal seek scheme; storing a seek driving
current trajectory value for driving a voice coil motor, the seek driving
current trajectory value being generated from the test seek routine;
calculating a primary harmonic sinusoidal coefficient by performing a
discrete Fourier transformation on the driving current trajectory value;
calculating a primary harmonic sinusoidal coefficient from a
multiple-sinusoidal-seek design current trajectory applied to the test
seek; and defining a torque constant correction value as a ratio of the
primary harmonic sinusoidal coefficient calculated by performing the
discrete Fourier transformation to the primary harmonic sinusoidal
coefficient calculated from a multiple-sinusoidal-seek design current
trajectory.