Split-actuator disk drive that uses microactuator feedforward to reduce effects of cross-actuator coupling

A method of manufacturing a disk drive including

• first and second heads;
• a first microactuator configured to move the first head relative to a disk;
• a second microactuator configured to move the second head relative to a disk;
• a first arm that is coupled to a first voice coil motor (VCM) and to which the first head and the first microactuator are mounted;
• a second arm that is coupled to a second VCM and to which the second head and the second microactuator are mounted;
• a first controller configured to generate a first control signal for moving the first arm and a second control signal for the first microactuator in response to a first position signal generated by the first head;
• a second controller configured to generate a third control signal for moving the second arm and a fourth control signal for the second microactuator, in response to a second position signal generated by the second head;
• a third controller configured to generate a feedforward correction signal for modifying the second control signal;
• and
• a notch filter configured to generate a fifth control signal for the first microactuator based at least on the feedforward correction signal,
• said method comprising:
• determining a first transfer function that models the feedforward correction signal as a function of the third control signal;
• and
• modifying the third controller to generate the feedforward correction signal based on the first transfer function.