Abstract: A high-speed disk drive system that features significant performance improvements over previously available systems. By immediately fetching the data as soon as heads reach the destination cylinder, internally stripping the data across the surfaces and plurality of read/write heads on every surface the data transfer speeds many times depending on other characteristics of the system. By implementing plurality of read/write heads and internal parity surfaces or distributed parity blocks/zones the system achieves higher reliability (fault resistance) with head and surface fail-over fail-safing.

Abstract: A sensor system for a disk device by using a floating head, comprising a head element that floats over a data recording area of a rotating disk so as to write data thereon or read data therefrom, a first actuator for moving the head element over the data recording area of the disk, and a second actuator supported by the first actuator and supporting the head element for precisely positioning the head element against the data recording area of the disk. The sensor system is capable of detecting any contact between the disk and the head element by utilizing a signal generated by the second actuator when the disk contacts the head element during an operation of the disk.

Abstract: Provided are a method, system, and program for estimating coil resistance of a voice coil motor for an actuator assembly in a disk drive system. An estimation is made of a calibration coil resistance during a calibration operation. A determination is made of a distance moved during a seek operation. The determined distance and the calibration coil resistance are used to estimate a current coil resistance following the seek operation.

Abstract: Vibration detector receives as an input a relative displacement signal corresponding to a displacement distance of fine actuator, and extracts only a high frequency component. Fine actuator is driven according to a composite signal generated in fine motion corrector by combining the high frequency component with fine motion control signal produced on the basis of position error signal. In addition, coarse actuator is driven according to a composite signal generated in coarse motion corrector by combining the high frequency component with coarse motion control signal produced on the basis of the relative displacement signal. According to the above configuration, a head positioning device employing a two-stage actuator is able to perform positioning control with stable operation even when it receives external disturbances such as vibrations and impacts.

Abstract: A head positioner comprises a degradation detecting unit for detecting degradation of a fine motion actuator based on current flowing through a piezo element constituting the fine motion actuator and a performance recovering unit for repairing the degradation when the degradation is detected. A fine motion driver has a function of generating a fine motion driving signal, a function of generating a predetermined voltage used for detecting the degradation, and a function of outputting a high voltage signal used for repairing the degradation. Therefore, the present invention can provide a head positioner for realizing stable positioning control for a long time even when degradation of the positioning performance is generated by an electric short circuit or the like, and provide a disk drive.

Abstract: A read/write head microactuator includes first and second insulating deposits that are flat, spaced apart by an air gap, and laterally movable responsive to a microactuator electrical drive current. First and second flat, interdigitated drive electrode deposits are deposited on the first insulating deposit. A flat, digitated sense electrode deposit is deposited on the second insulating deposit. The sense electrode deposit provides a relative position output. The sense electrode deposit faces both the drive electrode deposits across the air gap.

Abstract: An apparatus and method of maintaining stability in a servo loop of a disc drive is provided. A dither signal (a single frequency sine wave or a multi-frequency signal) is injected into the servo loop. A servo loop gain error signal is obtained in response to the injected dither signal. A gain of the servo loop is adjusted as a function of the servo loop gain error signal in real-time.

Abstract: The present invention is directed to utilizing the capabilities of multi-stage actuators in disk drives to do self servo writing on the disk surfaces, thereby avoiding the use of a servo track writer. In one embodiment, a crash stop that limits the range of motion of a primary actuator is used as an initial reference point for a secondary actuator associated with a first head to position the first head to write a first servo track on a first disk surface. The first servo track is subsequently used as a reference point for a secondary actuator associated with a second head to position the second head for writing one or more servo tracks on a second disk surface. One of these servo tracks on the second disk surface is then used as the reference point relative to which the primary and/or secondary actuator associated with the first head moves the first head to write one or more servo tracks on the first disk surface.

Abstract: A disc drive system includes a recording disc rotatable about an axis, a slider supporting a transducing head for transducing data with the disc, and a dual-stage actuation assembly supporting the slider to position the transducing head adjacent a selected radial track of the disc. The dual-stage actuation assembly includes a support structure supporting the slider in proximity to a surface of the disc, a microactuator and a capacitive position sensor. The support structure is coarsely positionable by a main actuator. The microactuator includes a stator attached to the support structure and a movable rotor operatively attached to the slider, the rotor being connected to the stator by at least one flexible beam. The capacitive position sensor connects the stator to the rotor, and provides a relative position signal representing a state of displacement of the microactuator.

Abstract: A head positioning apparatus capable of positioning a head at high speed and with high accuracy is provided. The head positioning apparatus includes a magnetic head 15, a head supporting mechanism 14, a coarse actuator 12, a fine actuator 13, a head position detection part 7, a fine movement control system 8 for controlling the fine actuator 13 based on the head position detected by the head position detection part 7, a head moving distance estimation part 3 estimating the head moving distance representing the distance the magnetic head 15 moves, and the coarse movement control system 4 for controlling the coarse actuator 12 based on the head moving distance estimated by the head moving distance estimation part 3.

Abstract: An actuator control system for a two-stage actuator system of a disc drive has a first, or primary, stage actuator consisting of a voice coil motor that positions the head relative to a disc and a microactuator that alters the actuator system without operation of the voice coil motor. A control loop includes a controller responsive to seek commands to operate the voice coil motor, thereby moving the head relative to the disc. An active damping circuit is coupled to the head to operate the microactuator to damp resonance modes of the actuator system.

Abstract: A circuit estimates speed of an electromagnetic actuator associated with a reading head of a disk storage unit and a digital controller. The circuit includes first and second supply terminals and an output terminal, with the first supply terminal being connected to the electromagnetic actuator. A measuring resistor is connected to the second supply terminal, and is connected in series with the electromagnetic actuator for measuring a current which passes therethrough when a supply voltage is applied between the first and second supply terminals. An adder has an output connected to the output terminal for providing an output voltage, a first input is connected to the first supply terminal, and a second input is connected to the second supply terminal. An adjustable-gain amplifier is connected between the measuring resistor and the second input of the adder for transferring the supply voltage and a voltage across the measuring resistor to the adder.

Abstract: A slider for carrying and finely adjusting both a radial position and a flying height of a transducing head with respect to a track of a rotatable disc includes a stator portion carried by a support structure such as a flexure of a disc drive system. A plurality of springs extend from the stator portion and are flexible in a lateral direction (for radial positioning) and in a vertical direction (for flying height control). A rotor portion is connected to the stator portion by the plurality of springs. The rotor portion carries the transducing head. The stator portion includes a plurality of stator electrodes, and the rotor portion includes a plurality of rotor electrodes suspended between the stator electrodes. Selected voltages are applied to the stator electrodes and the rotor electrodes to create a selected force in the lateral and vertical directions for moving the rotor portion with respect to the stator portion to finely adjust the radial position and flying height of the transducing head.

Abstract: A method is used for moving a transducing head between tracks of a disc in a dual-stage actuation assembly. The dual-stage actuation assembly has a main actuator for coarse positioning of the transducing head and a microactuator for fine positioning of the transducing head. The method comprises accelerating the main actuator during coarse positioning of the transducing head and applying control pulses to the microactuator during coarse positioning by the main actuator to eliminate oscillation of the microactuator during and after coarse positioning.

Abstract: A positioner (20) for a disk drive (10) that includes a magnet assembly (52), a conductor assembly (54), and a control system (22) is provided herein. The magnet assembly (52) includes a pair of magnet arrays (56A) (56B) and a pair of spaced apart flux return plates (75A) (75B). The conductor assembly (54) includes at least a first coil array (80) and a second coil array (82) that are substantially co-planar. The control system (22) directs current to electrically excite the coil arrays (80) (82) to maintain a data transducer (50) on a target track (32) of a storage disk (28).

Abstract: A micro-actuator of a head suspension either is wired in a reverse polarity to effect movement of the suspension arms in opposing directions relative to the magnetic disks or reversed in physical orientation and wired identically. This permits a single micro-actuator control signal to control all micro-actuators and thereby cancel the affects of inertia of the suspension arms and the read/write heads on the actuator arms as half of the suspension arms and magnetic heads move in one direction while, simultaneously, the other half of the suspension arms and magnetic heads move in a second, opposite direction in response to a single control signal, simplifying wiring and control electronics. The counter-movement of the suspension arms and magnetic counter the inertia and inertial forces and expedite the settling into their stable recording/reading positions, thereby reducing seek times and improving disk drive performance.

Abstract: A disc drive having a voice coil actuator with an attached suspension and head, the head including a micro-actuator. The micro-actuator having at least one natural frequency and at least one natural frequency time period. The voice coil actuator is adapted to attenuate a resonance of the micro-actuator at the at least one natural frequency using a stepped acceleration.

Abstract: A disk drive is disclosed comprising a voice coil motor (VCM) actuator and a piezoelectric (PZT) actuator. The VCM actuator is driven by a control effort including an integrator, and the PZT actuator is driven by a control effort including a transformer.

Abstract: A head position control system for a dual stage actuation disk drive system. A feedback system is provided for modifying a primary and a secondary input command signal to produce primary and secondary error signals. A controller receives the primary error signal and transmits primary actuator arm positioning information to the primary actuator. A secondary controller receives the secondary error signal and transmits secondary actuator arm positioning information to the secondary actuator. The feedback system creates a position error signal (PES) using information from servo wedges and runout information and the PES is used to produce the secondary error signal. The feedback system produces a reconstructed error signal including angular position information for the primary actuator arm by processing a back electromotive force signal from the primary actuator. The primary error signal is produced by modifying the primary input signal with the reconstructed error signal.

Abstract: The position information of the magnetic head is generated also from the data area to improve the positioning accuracy. The magnetic disk drive has a function of oscillating the magnetic head in the radial direction in the data area at a specific frequency and a function of detecting a read signal during the execution of the oscillation function and detects position information of the magnetic head from the detected read signal. The magnetic head position control can be performed in the data area. The magnetic head position signal not dependent on the frequency of a sampling signal generated from the servo information area can be generated. This in turn improves the data recording density and allows a highly precise position control of the magnetic head, thus improving the reliability of the magnetic disk drive.

Abstract: A disc drive including a rotatable data track, a dual-stage actuator with a primary actuator motor supporting an actuator arm, a read/write head supported by the actuator arm and communicating with a secondary actuator motor, and steps for controlling range of motion of the secondary actuator motor. The controlling steps include supplying and sustaining a bias signal to a single-sided unipolar device driver that then apply a bias voltage the secondary actuator motor to induce the secondary actuator motor to expand substantially one half of its expansion capabilities. And, confining correction signals provided by a control circuit of the disc drive, used in correcting mechanical position of the secondary actuator motor, to a voltage ranging substantially between a positive “+” and negative “−” voltage substantially equal to the applied bias voltage.

Abstract: A method and system for providing plant variation compensation for a microactuator in a dual-stage servomechanism of a disc drive. The method includes performing indirect adaptive filtering to identify plant variation in the microactuator, and tuning a compensator for the microactuator based on the plant variation. The indirect adaptive filtering can be performed using a two-stage process, including a first stage of adaptive modeling for the dual-stage servomechanism and a second stage of generating an indirect mode-reference inverse for the microactuator. A combined process can alternatively be employed. The microactuator can be a piezoelectric microactuator which forms a PZT system. The dual-stage servomechanism also includes a coarse actuator such as a voice coil motor.

Abstract: Disclosed is an apparatus and method for reducing vibration in dual stage actuators of storage devices such as hard disk drives. The apparatus comprises a compensating mass disposed on an outer arm of the storage device in order to balance the mass and inertia of the outer arm. The compensating mass is provided with an actuator that is driven in unison with a dual stage actuator also disposed on the outer arm. The excitation caused by the dual stage actuator is balanced by the excitation caused by the actuator of the compensating mass. The shape and mass of the compensating mass are selected to simulate the mass and inertia of the inner dual stage actuator. By driving the inner dual stage actuator in unison with the actuator and compensating mass, the torsional input of the voice coil motor is substantially reduced.

Abstract: A read/write head microactuator includes first and second insulating deposits that are flat, spaced apart by an air gap, and laterally movable responsive to a microactuator electrical drive current. First and second flat, interdigitated drive electrode deposits are deposited on the first insulating deposit. A flat, digitated sense electrode deposit is deposited on the second insulating deposit. The sense electrode deposit provides a relative position output. The sense electrode deposit faces both the drive electrode deposits across the air gap.

Abstract: A first estimator 13 estimates the position of a head based on a VCM driving signal u1 and a voltage signal Va output from a VCM 6 to output a first head position estimation signal x1est. The first estimator 13 estimates the disturbance acting on a head supporting mechanism 8 to output a disturbance estimation signal &tgr;dest. A second estimator 15 estimates the displacement of the head based on a control signal c2 for a fine adjustment actuator 7 to output a displacement estimation signal x2est. The first head position estimation signal x1est and the displacement estimation signal x2estare added together to obtain a second head position estimation signal xest. A position error signal e is generated using a head position signal x obtained by detecting the servo information and the second head position estimation signal xest. A disturbance compensator 10 synthesizes a VCM control signal c1 with the disturbance estimation signal &tgr;dest to generate the VCM driving signal u1.

Abstract: A head suspension supporting a head at the tip end is allowed to swing at the tip end of a carriage in a recording disk drive. A microactuator is interposed between the head suspension and the carriage. A resistor is connected to the microactuator in serial. The microactuator is allowed to function as a capacitance. A combination of the microactuator and the resistor enables establishment of a so-called low pass filter. A high frequency noise involuntarily introduced in the driving voltage for the microactuator can be eliminated or removed from the driving voltage. Elimination of the high frequency noise enables a reliable prevention of the mechanical or physical resonance or vibration in the head suspension. A tracking action of the head related to a target recording track can reliably be stabilized.

Abstract: By increasing the gain of a controller for coarse motion CFBV within a frequency band in which the gain of a sensitivity function SP=1/(1+PP·CFBP) of fine motion actuator DP and controller for fine motion CFBP exceeds 0 dB, the gain of a sensitivity function SV=1/(1+PP·CFBV) of coarse motion actuator PV and coarse motion controller CFBV is decreased. Through this, in a two-stage actuator control system, a disk apparatus can be provided in which a sensitivity function SPES=1/(1+PP·CFBP)·1/(1+PP·CFBV) indicative of a disturbance compressive ratio in a signal path ranging from disturbance components to a head position error signal is rendered to be 0 dB or less at all frequencies concerned.

Abstract: An apparatus and method for sensing the position of a read/write head or transducer carried by a microactuator at a distal end of a primary actuator in a head disc assembly of a disc drive. The position sensing system has a fixed member attached to the primary actuator and a moveable member attached to the fixed member by an attachment device. The attachment device permits the moveable member to move in relation to the fixed member along a predetermined pathway. A secondary voice coil motor (VCM) drives the movement of the microactuator via a VCM coil that is affixed to the moveable member, wherein a high frequency signal is applied to the VCM coil. At least one sense coil is attached to the fixed member and positioned near the VCM coil, such that the sense coil will receive a portion of the high frequency signal transmitted from the VCM coil through mutual magnetic coupling.

Abstract: A method and apparatus for controlling the position of a computer hard disk drive transducer head are provided. According to the invention, an initial value compensation scheme is applied to a signal derived from available states of the transducer head when the control mode of the disk drive switches from a track seek mode to a settling mode. In particular, at least portions of a the compensation signal are provided to both a coarse actuator and a microactuator associated with the transducer head. According to one embodiment of the present invention, high frequency components of the compensation signal are generally provided to the microactuator, while low frequency components of the compensation signal are generally provided to the coarse actuator. The method and apparatus of the present invention provide a computer hard disk drive having improved performance due to reduced settling times and improved audible characteristics.

Abstract: A disk drive apparatus. The apparatus has a platter operably coupled to a servo drive device. The servo drive device is adapted to rotate the platter about a fixed axis. The apparatus also has a support member operably coupled to the platter to move the support member about one or more active regions on a surface of the platter. The apparatus has a read/write head including an active portion and a support portion. The support portion is coupled to the support member. The active portion is operably coupled to the platter to read and/or write information to the surface of the platter. A piezo electric actuating material is coupled between the support portion of the read/write head and the support member. A first electrode is coupled to a first side of the piezo electric actuating material. A second electrode is coupled to a second side of the piezo electric actuating material.

Abstract: A magnetic disk device comprises at least a disk having information, at least a head for reading or writing information from or into the disk, at least a micro actuator for supporting the head and positioning the head, a coarse actuator for carrying the micro actuator and positioning the head, a controller for controlling the micro actuator and the coarse actuator based on the servo information read by the head, and a host controller for determining that information is to be read. In the case where the host controller determines that the operation is in a wait mode, the positioning operation of the micro actuator is stopped.

Abstract: A head drive device for positioning a read and/or write head for reading and/or writing information to and from a disk coated with a recording medium, the head drive device including a carriage, a main actuator for moving the carriage, a plurality of heads for reading and/or writing information to and from the disk, and a vibration control portion comprising a plurality of micro-actuators positioned between the carriage and the heads, such that when the main actuator and a first micro-actuator are driven to enable precise positioning of a desired head with respect to a surface of the disk a second micro-actuator is driven so as to offset vibrations generated at the carriage by the operation of the desired micro-actuator.

Abstract: A read/write head servo control system for data recording devices, wherein a method of compensating initial values is utilized to generate a control signal to move the head from an initial position to a target position. The method estimates and stores multiple position compensation values. A first control signal moves the head from an initial position to a target position. Head position values are sampled as the head moves. Head position deviation values are calculated for the sampled position values. The head position values are utilized to select a set of estimated position compensation values. These values are in turn utilized to generate a second control signal, which is then utilized to control the position of the head.

Abstract: A servo controller controls the servo system in a disc drive. A proportional integrator component receives the target track signal indicative of a target track and a measured track signal indicative of actual or measured data head position. During seek mode, the proportional integrator provides an output signal based on the measured track signal and the target track signal. A profile generator component provides a profile signal based on the output signal from the proportional integrator. A coarse actuator is driven based on the profile signal. A filter component is coupled to the profile generator and filters the profile signal to provide a filtered profile signal. The fine actuator is driven based on the filtered profile signal.

Abstract: A head carriage assembly drive system has a head carriage assembly having a head, a head carriage for moving the head in a radial direction of a rotating disk, a first drive unit for generating the power to rotate the head carriage and a second drive unit having a torque constant smaller than the torque constant of the first drive unit. Mainly the first drive unit is operated in a low-frequency band and mainly the second drive unit is operated in a high-frequency band, thereby reducing overall power consumption during tracking.

Abstract: A first actuator for controlling positions of all of a plurality of heads within a wide area and a plurality of second actuators for individually controlling the heads within small areas are provided. When two or more of the heads are in write or read state, one or more of the heads, which are not in write or read state, is preliminarily move to a track position to be accessed next.

Abstract: A control system for a data storage device including a constraint or weight to control stroke utilization and/or closed loop response of the control system. In particular, in one embodiment described, the weight or constraint is used to limit stroke utilization for a microactuator having a smaller stroke than a primary actuator. As described, the constraint or weight is used in conjunction with a mathematical synthesis to synthesize a controller to optimize system performance.

Abstract: A head actuator includes a head slider for carrying a head for recording information to or reproducing information from a recording medium; and a head supporting member for supporting the head slider. The head supporting member includes a substrate and a driving element provided on at least one surface of the substrate for generating an expanding and contracting force in a longitudinal direction in accordance with an external signal, wherein the external signal is applied to the driving element so as to expand or contract the head supporting member in the longitudinal direction and to position the head in a radial direction of the recording medium. The head supporting member includes a first area on which the head slider is provided, a second area on which the driving element is provided, and a third area for connecting the first area and the second area. The driving element has a geometrically central face.

Abstract: A head carriage assembly drive system has a head carriage assembly having a head, a head carriage for moving the head in a radial direction of a rotating disk, a first drive unit for generating the power to rotate the head carriage and a second drive unit having a torque constant smaller than the torque constant of the first drive unit. Mainly the first drive unit is operated in a low-frequency band and mainly the second drive unit is operated in a high-frequency band, thereby reducing overall power consumption during tracking.

Abstract: A system and method for controlling vibration of a piezoelectric microactuator in a disc drive are disclosed. The mechanical strain on the piezoelectric microactuator is ascertained and fed back to a controller which provides an electrical signal to the piezoelectric microactuator based upon the sensed strain. The electrical signal provided to the piezoelectric microactuator produces a mechanical force on the microactuator which counteracts the sensed strain. In one embodiment, a bridge circuit is coupled to the piezoelectric microactuator. The bridge circuit is adapted to sense a voltage across the piezoelectric microactuator and to separate the voltage across the piezoelectric microactuator into a voltage externally applied to the piezoelectric microactuator and a voltage induced on the piezoelectric microactuator by mechanical strain.

Abstract: The present invention includes a servo control system for controlling a dual stage actuator in a disc drive. The disc drive includes a data head for accessing information on a disc surface, and the dual stage actuator includes a coarse actuator and at least one fine actuator. The control system includes a fine actuator driver and a coarse actuator driver for driving the fine and coarse actuators, respectively. The control system also includes an observer which receives the coarse and fine actuator input signals and estimates a response of the coarse and fine actuators. A gain boost circuit is coupled to the fine and coarse actuator drivers and introduces a gain boost to reduce track following error in a desired frequency range.

Abstract: A servo system and method position a head laterally with respect to defined servo tracks, employing fine and coarse actuators. A servo control integrates the position error between the head and a desired position in accordance with a predetermined function, and operates the coarse actuator to translate the fine actuator and the head in accordance with the integrated position error. A position error signal loop is coupled to a servo sensor for determining position error for operating the fine actuator to translate the head in a manner to reduce the position error. The position error signal loop may have a compensator function with both integration and other functions. A coarse servo control comprises a connection coupled to the compensator function for providing an integration control representing the integration function of the position error signal loop; and a driver coupled to the connection, operating the coarse actuator to translate the fine actuator and the head in accordance with the integration signal.

Abstract: A head positioner comprises a degradation detecting unit for detecting degradation of a fine motion actuator based on current flowing through a piezo element constituting the fine motion actuator and a performance recovering unit for repairing the degradation when the degradation is detected. A fine motion driver has a function of generating a fine motion driving signal, a function of generating a predetermined voltage used for detecting the degradation, and a function of outputting a high voltage signal used for repairing the degradation. Therefore, the present invention can provide a head positioner for realizing stable positioning control for a long time even when degradation of the positioning performance is generated by an electric short circuit or the like, and provide a disk drive.

Abstract: A micro-mover system includes an information storage unit having multiple pairs of parallel plates closely spaced from each other to enable the exchange of information. A micro electromechanical system (MEMS) motor is associated with each pair of plates to move one of each pair of parallel plates in a plane parallel to the other plate in each pair to facilitate the exchange of information between each pair of plates. One pair of parallel plates is oriented to move in a direction opposite to another pair of parallel plates. Control circuitry is associated with each MEMS motors to coordinate the plate pair movements associated with that motor, so that the motion of one plate in one set of parallel plates occurs at the same time and in a direction opposite to the movement of the one plate of another set of parallel plates, thereby canceling a substantial level of total momentum arising from movement within the micro-mover system.

Abstract: A disk drive having an arm assembly equipped with a primary actuator such as a VCM and a mode-canceling actuator such as a PZT mounted at a location selected in such a way that the strain in the mode-canceling actuator is in phase with sway deformations of the primary actuator produced by the vibrational modes of the arm assembly. The primary actuator is driven to exert a primary force, f ⋁ pm , on the arm assembly while the secondary driver ensures that the mode-canceling actuator applies a mode-canceling force, f ⋁ m ⁢   ⁢ c , on arm assembly such that the gain and phase of one or more vibrational modes are canceled.

Abstract: Vibration detector receives as an input a relative displacement signal corresponding to a displacement distance of fine actuator, and extracts only a high frequency component. Fine actuator is driven according to a composite signal generated in fine motion corrector by combining the high frequency component with fine motion control signal produced on the basis of position error signal. In addition, coarse actuator is driven according to a composite signal generated in coarse motion corrector by combining the high frequency component with coarse motion control signal produced on the basis of the relative displacement signal. According to the above configuration, a head positioning device employing a two-stage actuator is able to perform positioning control with stable operation even when it receives external disturbances such as vibrations and impacts.

Abstract: In a magnetic recording device, a control element placed on a flexible wiring board between a control device and first actuators includes a plurality of actuator-driving-signal connecting terminals connected to a plurality of second actuators, an actuator-driving-signal input terminal to which driving voltage for the second actuators is input from the control device, connecting wires for connecting the actuator-driving-signal input terminal to the actuator-driving-signal connecting terminals, signal selection elements incorporated in the connecting wires, and a decoder for selecting one of the signal selection elements so that a specific actuator-driving-signal connecting terminal is connected to the actuator-driving-signal input terminal.

Abstract: The present invention includes a servo control system for controlling a dual stage actuator in a disc drive. The disc drive includes a data head for accessing information on a disc surface, and the dual stage actuator includes a coarse actuator and at least one fine actuator. The control system includes a fine actuator driver and a coarse actuator driver for driving the fine and coarse actuators, respectively. The control system also includes an observer which receives the coarse and fine actuator input signals and estimates a response of the coarse and fine actuators.

Abstract: A method and apparatus for resolving a “continuity” problem that occurs when modes are switched in the head positioning control process, and a contradiction exists between a short seek and a long seek.

Abstract: Piezoelectric elements or similar microactuators perform fine positioning in a system including at least two masses bendably coupled to a larger body. A servo controller receives a position signal from a sensor on the first mass, from which it generates a signal to control microactuators coupling other masses to the body. The movement of the other masses thereby exerts a controlled reactive force upon the body and upon the first mass. Examples include disc drive systems in which the reactive forces are used to counteract one or more unwanted excitations in an actuator body or actuator arm.