Seek control and settling control taming actuator resonance of hard disk drives

Novel fast seek and settling controls for hard disk drives (HDDs) have been developed. The controls are suitable for digital control and can be implemented into the servo program of a HDDs microcontroller easily. The controls use a feedback control and a feedforward control that uses feedforward trajectory with little power at actuator resonance frequencies. A finite-impulse-response notch filter is used to design the feedforward trajectories. The seek control uses the pair of feedforward trajectories of position and current. The settling control that connects a long-distance seek control with a following control uses two pairs of feedforward trajectories for initial position and initial velocity and a new bias-estimation method. The authors prove both controls are fast and free from residual vibrations and bias offset.