Magnetic disk device, electronic apparatus and, head control method

A magnetic disk device comprising:

• a head to perform read and write of information over an information storage medium having servo information;
• a coil motor to move the head;
• a drive circuit to drive the coil motor;
• a voltage detector to detect an inter-terminal voltage of a coil included in the coil motor;
• a head position calculation unit to calculate a position of the head for each sampling cycle on the basis of the servo information;
• a velocity calculation unit to calculate a velocity of the head at the position for each sampling cycle;
• a counter electromotive voltage calculation unit to calculate a counter electromotive voltage of the coil for each sampling cycle;
• a coil resistance estimation unit to successively estimate a coil resistance value of the coil on the basis of the velocity and the counter electromotive voltage;
• and
• a control unit to calculate a drive instruction for controlling the velocity for each sampling cycle on the basis of the counter electromotive voltage and to output the drive instruction to the drive circuit,
• wherein
• the counter electromotive voltage calculation unit subtracts a voltage drop to be caused by the coil resistance estimate value to be estimated by the coil resistance estimation unit from the inter-terminal voltage to calculate the counter electromotive voltage.