Abstract: A position controller of a motor in which the position time can be shortened even if an external force is applied. A speed control unit (13) comprises a compensation low-pass filter (133) having a transfer function corresponding to a delay of a speed control system. The speed control unit (13) further comprises an integral control system including a speed integrator (132) for integrating the difference between a speed and a delay speed command to the low-pass filter (133) compensating the delay in the speed control unit. A proportional control system outputting a command proportional to the speed command, and a multiplying means (134) for multiplying the sum of outputs from the integral control system and the proportional control system by a speed proportional gain and outputting the result as a torque command.

Abstract: A driving apparatus for moving an object. The apparatus includes a first actuator which drives the object in X and Y directions, a second actuator which drives a reaction force counter which receives a reaction force generated when the first actuator drives the object, and a controller which controls the second actuator on the basis of X- and Y-direction positions of the object and X- and Y-direction accelerations of the object so as to cancel, by the second actuator, the reaction force to be received by the reaction force counter when the object is driven by the first actuator.

Abstract: The present invention provides an electric motor movement controlling method, where the electric motor is fed by a total voltage proportional to the network voltage. The method comprises steps of making a first measurement of level of the network voltage at a first moment of measurement and making a second measurement of level of the network voltage; at a second moment of measurement, calculating the value of the derivative of the values of voltage measured in function of the first and second moments of measurement, to obtain a value of a proportional network voltage, and altering the value of the total voltage fed to the motor, proportionally to the value of the proportional network. A system that will implement the steps of the method of the present invention, as well as a compressor comprising the system of the present invention are foreseen.

Abstract: Torque control capability is provided to a position controlled robot by calculating joint position inputs from transformation of the desired joint torques. This is based on calculating the transfer function 1/E(s), which relates the desired joint torque to joint position. Here E(s) is a servo transfer function D(s) or an effective servo transfer function D*(s). The use of an effective servo transfer function D*s) is helpful in cases where joint nonlinearities are significant. The effective servo transfer function D*(s) is defined with respect to an ideal joint transfer function G*(s)=1/(Ieffs2+beffs), where Ieff is an effective moment of inertia and beff is an effective damping coefficient.

Abstract: A control method for controlling a speed of a movable machine element of a numerically controlled industrial processing machine with jerk limitation is described. The processing machine can be, for example, a machine tool, a production machine and/or a robot. A travel path of the movable machine element is first decomposed into a plurality of sequentially arranged, interpolatable travel sections. Jerk profiles are then determined for the interpolatable travel sections, which are modified with a parameter-dependent shape function. The modified jerk profiles provide a filter action that can be represented by bandpass filters having blocking frequencies. The blocking frequencies of the bandpass filters are selected so as to substantially correspond to characteristic frequencies of the machine element. The control method significantly improves the machine dynamics without sacrificing accuracy.

Abstract: A digital speed controlling apparatus includes: a target speed calculator that calculates a target speed of a driven conveyor belt, based on a sampling time; a current speed calculator that calculates a current speed of the conveyor belt, based on displacement and a difference of a sampling time; a target speed determining unit that determines whether a target speed is smaller than a predetermined value; a speed corrector that replaces the current speed with a set value, when the target speed is smaller than the predetermined value and also when the current speed is the minimum unit displacement per the sampling cycle; a speed error calculator that calculates an error between a replaced set value and the target speed; and an automatic controller that controls the drive motor based on a speed error.

Abstract: In one coordinate system of arbitrary rectangular coordinate systems including a coordinate system in which the position of a stator is fixed, a coordinate system in which the position of a rotor is fixed, and a coordinate system which rotates at a rotational frequency which is n times (n is an integer which is not 0 or 1) that of the rotor, a filter on any other coordinate system is defined. Further, driving of a motor is controlled by utilizing this filter. As a result, a coordinate transformation operation need not be individually performed with respect to control variables.

Abstract: A drive control apparatus, which controls an AC motor subjected to rotational drive by applying a rectangular wave voltage thereto, comprising: an actual torque detection section for detecting an actual torque value T outputted from the AC motor; an estimated torque calculation section for calculating an estimated torque value Tm based on a motor model with the AC motor in a simulated state; and a voltage phase calculation section wherein the voltage phase calculation section calculates a first voltage phase ?fb based on the actual torque value T and a command torque value T*, and a second voltage phase ?ff based on the estimated torque value Tm and the command torque value T* respectively, and outputs a value obtained by making the voltage phase subjected to weighting addition, as a voltage phase ?v.

Abstract: The present invention provides a motor drive apparatus capable of calculating an angular velocity and a rotation angle accurately in the entire rotation velocity range of a motor using a cheap Hall sensor having an inferior accuracy without using an expensive resolver having a high accuracy. The present invention includes a first angular velocity calculating means for calculating the angular velocity based on the back-EMF of the motor when it rotates at low speeds and a second angular velocity calculating means for calculating the angular velocity based on a signal from the Hall sensor when it rotates at high speeds. According to the present invention, the angular velocity and rotation angle can be calculated accurately in the entire rotation speed range using the Hall sensor under hybrid usage.

Abstract: There is provided a synchronous control device for driving the same control object with two servomotors. The synchronous control device detects the physical quantity that represents the difference between the forces on the two servomotors, and, on the basis of the detected value, reduces the force that acts between the two servomotors.

Abstract: A speed control means 7 for outputting a drive command signal for a motor 1 to make the speed of the motor 1 conform to the speed command signal based on a signal indicating the difference between the speed command signal and the detected speed of the motor; a filter 13 inserted in series with the speed control means 7 in the speed control loop, having a high frequency domain, a low frequency domain, and an intermediate frequency domain between the high frequency domain and the low frequency domain, a gain KL in the low frequency domain being larger than a gain KH in the high frequency domain, and having a phase lag characteristic so that the phase in the intermediate frequency domain is delayed; the speed control means 7 having a proportional controller 9 that multiplies input by a proportional gain KP and outputs the result, and the filter 13 being set so that phase lag occurs between a resonance frequency and an anti-resonance frequency of a mechanical system.

Abstract: An apparatus and method for controlling an inverter are disclosed to allow an inverter to provide a stable output voltage to a motor regardless of a change in a DC input voltage. A difference value between a reference voltage according to a predetermined rated voltage of a motor and a DC voltage of the inverter is obtained, a ratio of an output command frequency to a predetermined reference frequency is applied to the difference value to obtain a compensation output voltage value, a final compensation output voltage value is obtained by compensating the detected DC input voltage value with the compensation output voltage, and an output voltage of the final compensation output voltage value to the motor by the inverter. Thus, the stable output voltage of the inverter can be provided to the motor regardless of the change in the input voltage.

Abstract: A second member and a first member are applied with bias force to mechanically engage with each other at one of detent positions defining relative positions therebetween. An electric motor rotating a rotor therein when being supplied with electricity. Rotation of the rotor is transmitted to an output shaft manipulating the first member. A main controller controls the electric motor to switch the one of the plurality of detent positions. A rotor angle detecting unit detects rotor angle of the rotor. An output angle detecting unit detects output angle of the output shaft. The main controller includes a backlash calculating unit that calculates a backlash amount between the rotor and the first member in accordance with at least one of occurrence of a first region, in which change in the output angle is small with respect to change in the rotor angle, and a range of the rotor angle in the first region. The main controller incorporates the backlash amount into the control of the electric motor.

Abstract: A method and apparatus for compensating for the asymmetrical phases of a spindle motor in a disc drive are provided. With the apparatus and method, compensation values are learned by sampling speed data during a period of operation of the disc drive where the speed is stable and only one control operation is performed per revolution of the disc. The sampled speed data is used to generate the compensation values for each of the phases of the spindle motor. The compensation values are stored in a compensation mechanism which is used by the spindle motor speed controller to provide compensation for the asymmetrical phases of the spindle motor. During Normal operation, the actual speed output of the spindle motor is measured and is subtracted from a reference speed to generate a difference speed value. Based on the corresponding electrical phase, the correct compensation value is fetched and is subtracted from the difference speed value to obtain a compensated difference speed value.

Abstract: The invention provides techniques for reducing or altering the magnetic noise of an AC rotary electric machine. A magnetic noise reducing harmonic current of order n, whose frequency is n times the frequency of the fundamental frequency component of a polyphase AC current fed to an armature of a polyphase AC rotary electric machine, is superimposed on the polyphase AC current, thereby reducing or altering a harmonic component having a frequency (n?1) times the frequency of the fundamental frequency component and occurring due to a radial magnetic excitation force acting radially on an iron core of the AC rotary electric machine.

Abstract: A motor drive control apparatus for driving and controlling a linear vibration motor having a mover supported by a spring, with an AC current. The motor drive control apparatus includes a waveform creation unit for creating a comparative current waveform to be a reference of a driving current for the linear vibration motor based on the operating condition of the linear vibration motor, a current detector for detecting the driving current, and a controller for controlling a driving voltage of the linear vibration motor so that a difference between the comparative current waveform and a waveform of the current detected by the current detector becomes zero. The frequency of the driving current is controlled to be close to the resonance frequency of the linear vibration motor, based on the comparative current waveform.

Abstract: Embodiments of the invention provide a data storage apparatus and its control method capable of accurately reading/writing data.

Abstract: Embodiments of the invention provide a data storage apparatus and its control method capable of accurately reading/writing data.

Abstract: The present invention provides a motor control system and method thereof. The motor control system comprises a motor controller and a compensation device. The motor controller is used for generating a motor control output according to a reference signal and a first signal. The compensation device is used for generating a compensated motor control output according to the motor control output and a second signal. Moreover, the compensation device utilizes the compensated motor control output to reduce the steady-state phase error between the first signal and the reference signal.

Abstract: A control system having a floating deadband control includes an input device moveable from a first position to a second position. In addition, the control system includes a controller configured to automatically generate a first electronically defined deadband about the first position when the input device is at the first position and configured to automatically generate a second electronically defined deadband about the second position when the input device is at the second position.

Abstract: A correction value calculating method includes: preparing a printer including a motor, a PID control system for controlling the motor, and a memory for storing a correction value, the printer being configured to calculate a value of a current flowing through the motor based on the correction value and an output value of an integral element of the PID control system; obtaining in advance a relationship, for when a property of a motor fluctuates, between a correction value and a sum of an output value of the integral element when a motor is driven at a first velocity and an output value of the integral element when the motor is driven at a second velocity; driving the motor of the printer at the first velocity and measuring an output value of the integral element at that velocity; driving the motor of the printer at the second velocity and measuring an output value of the integral element at that velocity; and determining the correction value to be stored in the memory based on the relationship and a sum of the

Abstract: Servo control signals and data content associated with two different devices, such as a hard disc drive magnetic head and a digital video disc laser may both be processed without substantial loss of data or control signal errors using a single controller.

Abstract: An actuator control device includes an electrical control unit for detecting the present positions of output shafts of servo motors, and communicating with control circuits for driving the output shafts of the servo motors to target stop positions on the basis of the present positions thus detected. When it is judged that a present position of one of the output shafts thus receives is abnormal, the electrical control unit corrects the present position and transmits the corrected present position to the appropriate control circuit.

Abstract: An apparatus corrects a current value of a three-phase electric motor including a current detector that detects current of each of three phases including a first phase, a second phase, and a third phase. The apparatus includes a current-value correcting unit. When current of one of the first to third phase is zero-crossing, the current-value correcting unit corrects a current value of at least one of the others of the first to third phases on a basis of a correlation between detection values of the current detectors provided for the others of the first to third phases during a period in which the three-phase electric motor is operating.

Abstract: A configuration system for an intelligent assist system is provided. The intelligent assist system includes a module, and a computational node on the module. The configuration system includes a host computer system capable of executing a stored program. The host computer system is in communication with the computational node via a communication link. The system also includes a graphical user interface enabling a user to manipulate objects related to the module or the computational node, and a plurality of visual indicators corresponding to a status of the module, the computational node, or the communication link.

Abstract: A brushless DC motor has a stator and a rotor. An angle ?0 between an edge section of the flux barrier on a magnetic pole center side and an edge section on a side for coming in contact with the rib of adjacent flux barrier, with respect to the rotor center, is determined to be equal to or greater than an angle satisfying a following relationship ?0=180°*m/(Pn*f/f0) (provided 2?0??r<90°) wherein, a frequency of vibration which is to be reduced is represented with f, a pole pair number is represented with Pn, an electrical frequency is represented with f0=Pn*N, a motor revolution is represented with N, m=1, 3, 5, . . . , an angle of the rib with respect to the rotor center is represented with ?r, therefore making of motor highly effective and decreasing of the motor acoustic noise are coped with.

Abstract: When either a command value or an actually measured value is appropriately selected as an angular velocity used for the frictional torque calculation, the frictional compensation can be made valid at all times in both the case in which a robot is actively operated according to an angular velocity command and the case in which the robot is passively operated being pushed by an external force. In the case where a motor rotating direction and a collision direction are reverse to each other after a collision has been detected, the control mode is switched from the positional control to the electric current control and a torque, the direction of which is reverse to the direction of the motor rotation is generated by the motor, so that the motor rotating speed can be reduced and the collision energy can be alleviated.

Abstract: A minute object manipulating apparatus includes a tool which manipulates a manipulation target object, an observation unit capable of changing the magnification for observating the manipulation target object and tool, a display unit which displays magnified images of the manipulation target object and tool, which are observed by the observation unit, a command input unit to cause the operator to input the manipulation command signal of the tool, and a gain arithmetic unit which decides the manipulation gain of the tool on the basis of the magnification of the observation unit and magnified image information or pixel information on the display unit. The tool is driven and controlled on the basis of the manipulation gain and manipulation command signal.

Abstract: A servomotor driving controller capable of highly accurate machining, which prevents a quadrant projection upon change in the quadrant where machining is made. After the position deviation converges to zero by means of learning control, the velocity command or a difference between the velocity command and the commanded velocity which is the derivative of the position command is stored as velocity correction data. Until a predetermined time period elapses from when the sign of the position command is reversed, an amount of correction for each period of position loop processing is determined based on the correction data, and used to correct the velocity command.

Abstract: A motor controller system uses a rotary sensor with a plurality of signal conditioning units, coupled to the rotary sensor. Each of these units, which is associated with a particular range of motor output shaft rotation rates, generate a feedback signal indicative of the position of the motor's output shaft. A controller (i) converts a selected motor output shaft rotation rate to a corresponding incremental amount of rotational movement for a selected fixed time period, (ii) selects, at periodic completions of the selected fixed time period, the feedback signal from one of the signal conditioning units for which the particular range of motor output shaft rotation rates associated therewith encompasses the selected motor output shaft rotation rate, and (iii) generates a motor drive signal based on a difference between the incremental amount of rotational movement and the feedback signal from the selected one of the signal conditioning units.

Abstract: In one coordinate system of arbitrary rectangular coordinate systems including a coordinate system in which the position of a stator is fixed, a coordinate system in which the position of a rotor is fixed, and a coordinate system which rotates at a rotational frequency which is n times (n is an integer which is not 0 or 1) that of the rotor, a filter on any other coordinate system is defined. Further, driving of a motor is controlled by utilizing this filter. As a result, a coordinate transformation operation need not be individually performed with respect to control variables.

Abstract: A speed control apparatus includes a speed control part 12 for generating a source current command based on a difference between a speed command of a motor 4 and speed detection in which a speed of the motor 4 for driving a load 2 is detected, a notch filter 14 which can break a notch frequency resulting in a predetermined frequency selected among continuous frequency band widths and also generates a compensating current command in which the notch frequency is eliminated from the source current command signal, a notch filter adaptive part 16 for selecting the notch frequency so that the compensating current command in which a sustained vibration frequency component of the source current command is eliminated is generated from the notch filter 14, a subtracter 103 for generating an elimination portion current command resulting in a difference between the source current command and the compensating current command, and an adder 109 for adding the compensating current command and the elimination portion current

Abstract: A disk drive is disclosed comprising a disk, a head, and a voice coil motor (VCM) for actuating the head over the disk. The disk drive executes a rotational position optimization (RPO) algorithm to select a next command to execute relative to an estimated seek time computed for each command in a command queue. A seek time parameter is estimated and a seek time delta computed in response to the estimated seek time parameter. The seek time delta is added to a nominal estimated seek time to generate a modified estimated seek time for each command in the command queue, thereby optimizing the RPO algorithm.

Abstract: It is a biped (two-footed) walking humanoid robot, which is provided with drive motors (11d, 11e, 18L, 18R-24L, 24R, 28L, 28R-33L, 33R, 35, 36) to pivotally move respective joint portions, and a motion control apparatus (40) to drive-control respective drive motors, and said motion control apparatus (40), together with a detector (45) to detect the robot's current posture and others, compares the robot's detected current posture and others with next motion command input from outside, and if next motion command is within the range of stability limit with respect to the robot's current posture and others, the complementary data with respect to intermediate motion from current posture till initial posture of next motion command and the motion data corresponding to next motion command are generated, each drive motor is drive-controlled based on said complementary and motion data, and thereby various motions are conducted smoothly and continually.

Abstract: An electrically operated drive controller includes first and second electric current command value calculation processors, for calculating first and second electric current command values from a target value of torque of an electrically operated machine; a voltage command value calculation processor, for calculating a voltage command value from the first and second electric current command values; and first and second adjusting value calculation processor, for calculating first and second adjusting values. The first electric current command value calculation processor includes first electric current command value adjustment processors, for adjusting the first electric current command value by the first adjusting value, and an electric current limit processor, for limiting the adjusted first electric current command value.

Abstract: A control magnetic bearing device comprises a plurality of control magnetic bearings for contactlessly supporting a rotor, an electric motor for rotating the rotor, a magnetic bearing drive circuit for driving the magnetic bearings, an inverter for driving the electric motor, a main control circuit for controlling the magnetic bearing drive circuit and the inverter, and a power source unit connected to an external power source for supplying electric power to the magnetic bearing drive circuit, the inverter and the main control unit. The main control unit has software-programmable digital processing means for controlling the inverter in accordance with an input voltage value from the power source unit.

Abstract: An electrically operated drive controller includes first and second electric current command value calculation means which calculate first and second electric current command values based on a target value of torque of an electrically operated machine. The controller also includes a voltage command value calculation processing means which calculates a voltage command value based on the first and second electric current command values and an adjusting value calculation processing means for calculating an adjusting value of the first electric current command value and for performing weak field control based on the voltage command value. The first electric current command value calculation processor adjusts the first electric current command value based on the adjusting value. The second electric current command value calculation processor adjusts the second electric current command value based on the adjusted first electric current command value.

Abstract: A servo motor for driving a die is provided with position and speed detectors. Further, a pressure sensor for detecting the pressure applied to a workpiece is provided. In the servo motor control unit, the smaller one of the speed command obtained by feedback control of the position and the speed command obtained by the pressure feedback control is selected as an output of a comparator. Based on the speed command output from the comparator, feedback control of the speed is performed and the servo motor is driven. In the state where the die does not press against the workpiece, a pressure error is large, the speed command by pressure control becomes large, and the speed command by position control becomes small. Therefore, position control is performed. When the workpiece is pressed, the position error increases, and the pressure error decreases, a speed command by pressure control is employed and pressure control is performed.

Abstract: For outputting an amount of backlash compensation according to the direction of reversal in the reversal motion of the moving axis, three output modes are prepared: (a) a mode in which a preset backlash compensation is outputted all at once, (b) a mode in which backlash compensation is outputted according to distance traveled, and (c) a mode in which backlash compensation is outputted according to time elapsed. It is determined whether the motion of the moving axis has been changed from positive to negative directions or from negative to positive directions, and with this determination result, any one of the above three output modes (a) to (c) is selected.

Abstract: A motor control apparatus of the present invention comprises a velocity detector for detecting a rotation velocity of a mover of a motor, a position detector for detecting a position of the mover, a differentiator for performing time differentiation with respect to the position detected by the position detector to obtain a velocity calculation value, a feedback signal generating circuit for generating a feedback signal including the velocity detection value obtained by the velocity detector as a high frequency component and the velocity calculation value obtained by the differentiator as a low frequency component, and a linear amplifier and an integrating amplifier for performing PI control, the linear amplifier and the integrating amplifier performing linear amplification and integrating amplification of a difference between the velocity instruction and the feedback signal, respectively.

Abstract: The invention provides a method for controlling an electromechanical servomechanism (20) for moving an output member relative to a variable load (38). The servomechanism includes: a motor (37) having at least one coil (32A, 32B or 32C) adapted to be supplied with current and having a rotor (33) with an output shaft (35); a mechanical transmission (36) arranged between the output shaft and the load, the transmission having a mechanical friction related to the load; a servoamplifier (30) arranged to supply current to the motor coil in response to an input signal (in line 29); a command signal (in line 21) for commanding the position of the load; a load position feedback signal (in line 23) compared (in summing point 22) to the command signal and arranged to produce an error signal (in line 24); and means (28) for generating an offset signal (in line 26) that is summed (in summing point 25) with the error signal to modify the servoamplifier input signal (in line 29).

Abstract: The present invention provides an electric power steering device enabled to compensate for the influence of the inertia of a steering-assisting-force generating motor on steering with accurate timing even when a steering direction is reversed at high speed. Based on steering torque and a rotation angular speed of a steering-assisting-force generating motor, a steering angular acceleration correspondence value is obtained. The device has means for regulating a gain, which is multiplied to a change acceleration of the steering torque. The motor is controlled so that the steering assisting force is corrected according to a motor output correction value obtained on the basis of the relation between the motor output correction value and the steering angular acceleration correspondence value, which is preliminarily determined and stored in such a way as to compensate for the influence of the inertia on steering, and the obtained steering angular acceleration correspondence value.

Abstract: A method for increasing the control response of a drive train of a machine tool or production machine with backlash and/or elasticity is described. A combined signal comprised of the motor speed measured on the motor and the load speed measured near the load of the drive train is supplied to a controller. The combined signal can generated in one of two ways: (1) by weighting the measured motor speed with a first multiplication factor (?), by weighting the measured load speed with a second multiplication factor (1??), and by subsequently adding the weighted motor speed to the weighted load speed; or (2) by first subtracting the measured load speed from the measured motor speed, then weighting the resulting difference by a multiplication factor ?, and finally adding the load speed to the weighted difference.

Abstract: A positioning system for moving an object to a target position is presented. In an embodiment, the system includes a first actuator configured to exert a force on the object in a first direction in response to a control current, the actuator having an actuator gain and the generated force being a function of the control current and the actuator gain, the actuator including a magnet configured to induce a magnetic field; and a coil arranged in the magnetic field, the magnet and the coil being movable relative to each other. The system also includes a power supply configured to supply the control current to the actuator in response to a control signal; and a control system configured to control the force generated by the actuator by supplying the control signal to the power supply, the control signal being adapted to the actuator gain, the gain being predetermined as a function of a parameter.

Abstract: The present invention provides an electric brake system which detects the occurrence of overshooting, and corrects a feedback gain in the PID feedback control at overshooting. For example, it increases a differential gain Kd. Accordingly, a damping force increases from the time when the overshooting is determined, and after the overshooting, the output of an electric brake moderately decays to get closer to the target value with the passage of time.

Abstract: A method of compensation for current-sensor gain errors in an electric machine drive 14 includes a high frequency carrier signal electrically injected into the electric machine 14. A current-sensor signal of the electric machine 14 is determined. The current-sensor signal is separated into current-sensor carrier signal negative and current-sensor carrier signal positive sequence reference frames. A proportional compensator signal for one of the current-sensor carrier signal reference frames is generated in a feedback loop 24. A magnitude signal of another one of the current-sensor carrier signal reference frames is generated in a different feedback loop 26.

Abstract: To appropriately detect overload which may break a motor or deform a body and reduce the overload in the motor. The DC component of a load torque is derived from the sum of absolute values of a torque applied to a link connected to the output shaft of a motor and the generated torque of the motor, and it is determined that overload has been applied when the DC component exceeds a first threshold value for a prescribed period of time or longer. In addition, considering such a characteristic that the variation of energy applied to the output shaft of a motor is in proportion to a product of the torque and the angular velocity of the motor, the AC component of the load torque is detected based on the variation of energy, and it is predicted that overload will be applied when the AC component exceeds a second threshold value.

Abstract: A position controller for controlling a position of a feed shaft of a machine having a motor and the feed shaft driven by the motor is provided. A subtractor calculates a difference between a speed instruction and a speed detection value of a motor and outputs as a speed difference. An adder 20 adds the speed difference and a speed instruction compensation value and a speed difference proportion calculator calculates a proportional component of the speed difference based on the added result and a proportional gain. A speed difference integral calculator calculates an integral component of the speed difference based on the speed difference and an integral gain. An adder 6 adds the proportional component of the speed difference and the integral component of the speed difference to output a torque instruction.

Abstract: A head positioning system includes: a positioning mechanism section 1 for positioning a head 12; a position controller 2 for detecting a head position signal x to output a position control signal Ux; a velocity detector 3 for detecting the relative velocity of the head 12 with respect to a disk 7 based on the head position signal x; a counter electromotive voltage detector 4 for outputting an estimated head velocity signal Ve2 that is obtained by estimating the absolute velocity of the head 12 based on a counter electromotive voltage signal Vs of an actuator 50; an estimated velocity corrector 5 for correcting an estimation error of the estimated head velocity signal Ve2 based on a velocity signal detected from the head position signal x so as to output a corrected estimated velocity signal Ve2?; and an estimation controller 6 for outputting a velocity control signal Uv based on the corrected estimated velocity signal Ve2?, wherein the actuator 50 is controlled by a control amount signal U that is obtained by

Abstract: To appropriately detect overload which may break a motor or deform a body and reduce the overload in the motor. The DC component of a load torque is derived from the sum of absolute values of a torque applied to a link connected to the output shaft of a motor and the generated torque of the motor, and it is determined that overload has been applied when the DC component exceeds a first threshold value for a prescribed period of time or longer. In addition, considering such a characteristic that the variation of energy applied to the output shaft of a motor is in proportion to a product of the torque and the angular velocity of the motor, the AC component of the load torque is detected based on the variation of energy, and it is predicted that overload will be applied when the AC component exceeds a second threshold value.