Abstract: An integrated control and diagnostics system for a controlled system (e.g., a motor) includes a diagnostics module and a controller coupled to the motor. To optimize operation, the diagnostics information signal is used to modify the control provided by the controller as required. Moreover, the output of the control module is coupled to the diagnostics module so that the health assessment made by the diagnostics module can be based at least in part on the output of the controller. The invention uses a model-based diagnostics approach that allows integration of control algorithms with diagnostics algorithms to intelligently trade off optimizing performance to avert or accommodate failures, and to meet performance requirements in a wide range of applications.

Abstract: A motor speed control having synchronous PWM signals has a synchronous phase detecting unit and a PWM control unit. The synchronous phase detecting unit detects the phase variation of a Hall signal, which represents the phase change of the motor, and outputs a digital value to the PWM control unit. The PWM control unit compares the digital value with a speed control command so as to obtain a PWM signal, wherein the PWM signal is synchronized with the Hall signal. Since the PWM signal is synchronized with the Hall signal, the motor is operated smoothly even in the low speed rotation, and audible noises are effectively reduced.

Abstract: The invention relates to a method for regulating an electric-motor-driven adjusting device, in particular for vehicles, having a safety circuit (5) for reversing or stopping a drive motor, and to an apparatus for performing this method. To enable fast, safe detection in the event of something becoming caught or pinched, it is provided that an actual value is regulated via a closed-loop control circuit to a set-point value, the actual value or set-point value is a signal having a frequency proportional to the rpm or load on the drive motor, and the phase difference detected with a comparison member of the control circuit is utilized to activate the safety circuit.

Abstract: A device for receiving first and second analog signals consisting of two sinusoidal signals shifted in phase from an encoder and outputting digital pulses corresponding to the approximate number of equal steps the system of which the encoder is a part has advanced or retreated comprising flash memory storing a table relating total value counts to the precise value as previously determined by calibration and that adds or subtracts counts to or from a difference register so that the count in the difference register corresponds to the calibrated value moved by the system.

Abstract: To provide a spindle motor control method adapted to an optical disk recording and reproducing apparatus capable of recording a signal onto a disk using a laser applied from an optical pick-up, a reference signal originated from a disk (1) and a reference signal necessary for signal recording are synchronized to each other when resuming signal recording once suspended. The synchronization is established without using a phase error component. Once synchronization is established, a phase error component is added to a servo signal of the spindle motor (2). A gain for a phase error component is begun gradually increasing after a phase error component is begun being added to a servo signal. An upper limit value of the gain of a phase error component to be added is determined depending on the location of a part on the disk (1) at which to resume the once suspended signal recording.

Abstract: A closed-loop control of a servo motor in which multiple closed-loop terms of a motor command are adaptively tuned and selectively activated to achieve both stable operation and improved performance. The motor command includes a first term proportional to an error signal, a second term based on the integral of the error signal, and a third term based on the rate of change of the measured feedback signal, and representing the kinetic energy of the system. The first term is continuously active, whereas the second term is only activated when the rate of change of the measured feedback signal is below a threshold, and the third term is only activated when the error signal is within a reference window, thereby allowing relatively high gains while ensuring stable operation.

Abstract: The present invention supplies a position detection circuit, and a motor controller, that can not only obtain rotor position detection signals properly over the entire PWM control region, but also obtain these signals properly during PAM control. In a brushless motor controller based on the present invention to detect the magnetic pole position of the stator in the motor in accordance with the stator coil terminal voltages of multiple phases and control the energization of the stator coils, the comparison result information signal, after being obtained through comparison between the detected voltage values corresponding to the foregoing terminal voltages, and a reference voltage value, is directly entered into control circuits, then the position of the rotor in the motor is properly detected immediately after power-on switching, without a rotor position detection inhibition time interval being provided, and the motor is controlled properly.

Abstract: A control unit is arranged for a synchronous motor formed of a rotor provided with a magnet. The control unit includes a 180°-conduction drive unit for performing 180°-conduction drive of the synchronous motor, a 120°-conduction drive unit for performing 120°-conduction drive of the synchronous motor, a rotation speed calculating unit for calculating the motor rotation speed, a rotation-speed-vs.-efficiency table unit storing an efficiency relative to a rotation speed of the motor, and a drive method selecting unit for selecting an optimum drive method for the current rotation speed based on the current rotation speed and information stored in the rotation-speed-vs.-efficiency table unit. Thereby, the synchronous motor performs 120°- or 180°-conduction drive in accordance with the current rotation speed to achieve the drive with an optimum efficiency.

Abstract: A circuit to bypass the Zener diodes in the flyback circuit of a DC brush motor actuator which uses a voltage sensitive device to detect when the power to the motor is de-activated to control a switch that short circuits the Zener diodes.

Abstract: A position encoder and a method for estimating absolute position using two or more diffractive grating tracks of differing periods to generate interference fringe patterns on a multi-track sensor. Detectors, corresponding to the diffractive grating tracks, detect the interference fringes. A first processing circuitry coupled to the detectors extract phase signals from the signals from the detectors. A second processing circuitry then estimates the cycle counts of the track signals based on the phase signals from the first processing circuitry. The absolute position is estimated by combining the cycle count, the fractional fringe value, and the grating period.

Abstract: A method and system for detecting a change in the position of an electric drive motor in a vehicle power window system includes a current sensor for sensing a current of the motor, and generating an input signal having a phase associated therewith. A signal generator generates a reference signal having a predetermined phase and a frequency. A comparator is in communication with the current sensor and the signal generator for comparing the phase of the input signal with the phase of the reference signal. A control circuit, in communication with the signal generator, determines movement of motor based on the comparison. If the motor does not move while being commanded to close, an obstruction may be assumed to be present between the window and its respective frame.

Abstract: A device for receiving first and second analog signals consisting of two sinusoidal signals shifted in phase from an encoder and outputting digital pulses corresponding to the approximate number of equal steps the system of which the encoder is a part has advanced or retreated comprising flash memory storing a table relating total value counts to the precise value as previously determined by calibration and that adds or subtracts counts to or from a difference register so that the count in the difference register corresponds to the calibrated value moved by the system.

Abstract: An apparatus for reproducing information recorded on an optical disc which can favorably accomplish a time base correction for a read signal in a simple configuration. Also, the apparatus precisely removes jitter components produced when a driving signal is supplied to a spindle motor. The apparatus has a spindle motor for rotating an optical disc, a pickup for optically reading a recorded signal on the optical disc to generate a read signal corresponding to the recorded signal, and an A/D converter for digitizing the read signal to reproduced an encoded signal. The apparatus is provided with a controller for supplying the spindle motor with driving power. The controller has an unnecessary component removing filter for removing high frequency components from the motor driving power.

Abstract: A rotational pulse signal generating circuit for a commutator DC motor is made up of a filter device for eliminating noise from the motor, a cutoff frequency of the filter device being variable depending on an external signal; a pulse shaping device for generating a ripple pulse indicative of a rotational number of the motor by wave-shaping an output of the filter device; and a clock generating device for generating a clock signal on the basis of the ripple pulse and a rotational condition signal of the motor, the clock signal being fed to the filter device for making the cutoff signal thereof variable.

Abstract: A filter module inserted into a speed control loop to shorten the rise time of the loop. The filter parameters of the filters provided in the filter module and the controller parameters are calculated in such a way that instances of resonant rise. The amplification factors for the proportional controller branch and the integral controller branch are increased, which leads to a shorter rise time.

Abstract: An improved motor commutation pulse detection circuit for comparing a filtered motor current signal to a threshold value, where the circuit is responsive to the actual or expected amplitude of the commutation pulses for adjusting the motor current signal or the threshold value so that the compared threshold value is substantially equal in amplitude to minimum amplitude commutation pulses in the compared motor current signal. In one circuit, the threshold value is varied in accordance with the average current flowing through the motor at the time of the commutation event. In another circuit, the threshold is effectively switched between a high value and a low value depending on the mode of operation of the motor. A motor run detection threshold is activated during motor running periods, while a motor brake detection threshold is activated during motor braking.

Abstract: A spring return rotary actuator incorporating a DC brush commutated electric motor and a pulse width modulation drive circuit which reduces the voltage at which current is supplied to the motor once a rotation sensor senses that the actuator output shaft has stalled. The drive circuit also includes a temperature responsive feature which increases the voltage at which current is supplied to the motor in the event a sensed temperature exceeds a temperature limit.

Abstract: The present invention addresses a problem as to how to provide a motor control apparatus which has a magnetic pole position inferring means capable of inferring the position of a magnetic pole of a synchronous motor by adopting a simple method in a short period of time with a high degree of accuracy. In order to solve this problem, a signal id1* for inference use is applied and a peak value iqh of a response current iq′ is detected by an iq′ peak detecting unit. The peak value iqh is then supplied to a magnetic pole position inferring unit for inferring the position of the magnetic pole of the synchronous motor by carrying out multiplication processing.

Abstract: A circuit for driving a sensorless BLDC motor is disclosed which checks whether or not the motor is rotating and then terminates the start up interval (or forced drive interval) in order to obtain efficient motor drive. The present invention is comprised of a comparator which receives a phase voltage through a first input terminal and receives a neutral point voltage through a second input terminal, and a flip-flop unit which is comprised of a plurality of flip-flop devices. Each flip-flop device is a means for receiving an output of the comparator through a clock signal input terminal, and a reset signal through a reset signal input terminal. The sensorless BLDC motor operates in a running mode when data provided to the input terminal of the first flip-flop means is output from the output terminal of the last flip-flop.

Abstract: In a disk drive system, whether the rotation rate of a motor provided to drive a disk is within a rated rotation rate range or not is checked every time the motor makes one complete turn. When the rotation rate of the motor is found to be within the rated range a predetermined number of times consecutively, a status signal, which is used to indicate that the rotation rate of the disk is within the rated range, is brought into a state for indicating that the rotation rate of the disk is within the rated range. This not only prevents the status signal from oscillating at a high frequency, but also allows the status signal to be brought into the state for indicating that the rotation rate of the disk is within the rated range only after the rotation rate of the motor has settled within the rated range. Thus, it is possible to eliminate the possibility of malfunctioning of a disk drive apparatus due to the status signal.

Abstract: A method of detecting phase error between a phase current and a driving voltage includes generating a signal indicative of the phase current. The method includes identifying a time interval during which the signal indicative of the phase current is generally symmetric about a midpoint of the time interval when the phase error is approximately zero. The method further includes determining the extent to which the signal indicative of the phase current is symmetric about the midpoint of the time interval. Finally, in response to determining the extent to which the signal indicative of the phase current is symmetric, the method includes generating phase error information.

Abstract: In accordance with the described invention, a stepper motor that drives a printer's movable subsystem, e.g. a sled-mounted ink-jet service station, is replaced with a less expensive and quieter DC motor, and continuous positional feedback is obtained via a fixed subsystem-mounted optical sensor array in cooperation with a movable subsystem-mounted code strip that includes a home-position encoding region. The code strip produces in the optical sensor array, in reflective response to a fixed subsystem-mounted light source, a plurality of modulated signals as the substantial extent of the code strip passes by, thereby enabling positional tracking of the movable subsystem's motion, and produces a secure home-position identification signal set when the homing patch is in the `view` of the array.

Abstract: A motor control apparatus and a motor unit having such a motor control apparatus according to the present invention are constructed to detect a terminal voltage for switching elements of the same phase in a dead time period by a voltage output circuit 10, and to detect the instant when the sign of a phase current changes from the detected terminal voltage by a current sign change detection part 11. Based on the phase of a current sign change timing provided from the current sign change detection part 11 and the phase of a phase applied voltage, the first applied voltage control circuit 14 generates a phase applied voltage command to a switching element modulation circuit 9. Such arrangement makes it possible to provide motor continuous energization or motor energization drive near to 180 degrees at high efficiency, without the provision of any current sensors.

Abstract: In a rotating machine with employment of a sensor-less DC brushless motor, a terminal voltage of a motor is corrected in a phase corrector by using a motor phase current signal. At this time, the terminal voltage is processed in an integrator and a comparator so as to be converted into an ON/OFF signal having a duty ratio of 1:1. Then, a rotation signal is produced based on an induced voltage which is generated by rotating a permanent magnet rotor, so that a rotation sensor is no longer required. On the other hand, an output derived from the phase corrector is entered as a 1-pulse/1-rotation output signal into a PLL circuit. The PLL circuit contains a phase comparator, a low-pass filter, an oscillator, and a counter. The PLL circuit frequency-divides the 1-pulse/1-rotation output signal. The sine wave data are stored into a ROM with respect to each of the frequency-divided signal positions. The unbalance vibrations of the magnetic bearing are controlled every frequency-divided signal.

Abstract: A time-discrete phase-locked loop includes a discrete time oscillator (DTO) which supplies a periodical oscillator signal (OS) representing oscillator values (OV) at corresponding clock instants (TC) of a clock signal (CLK). A position-determining circuit (P) generates a time-discrete synchronization instant (SI) representing a position of an analog synchronizing pulse (SP) of a video signal with sub-clock period accuracy. A phase detector (PD) determines a phase error (PE) between the discrete time oscillator signal (OS) and the synchronization instant (SI) by using the synchronization instant (SI), a value (OV1) of the discrete time oscillator signal (OS) at a clock instant (TC1) related to the synchronization instant (SI), and the slope of the oscillator signal (OS). A period of the oscillator signal (OS) depends on the phase error (PE). By using the slope of the oscillator signal (OS), the phase error (PE) is independent of this slope.

Abstract: A slow-speed servomechanism includes a motor for driving a load; a direct drive transmission between the motor and the load; an incremental optical encoder connected to the load, the encoder having analog sine and cosine outputs; an analog to digital converter for converting the sine and cosine analog values to digital values; and a digital controller, connected to the motor and the analog to digital converter, for controlling the motor.

Abstract: The present invention addresses a problem as to how to provide a motor control apparatus which has a magnetic pole position inferring means capable of inferring the position of a magnetic pole of a synchronous motor by adopting a simple method in a short period of time with a high degree of accuracy. In order to solve this problem, a signal id1* for inference use is applied and a peak value iqh of a response current iq' is detected by an iq' peak detecting unit. The peak value iqh is then supplied to a magnetic pole position inferring unit for inferring the position of the magnetic pole of the synchronous motor by carrying out multiplication processing.

Abstract: A simple modification to a proportional integral controller allows for non-linear control strategies while maintaining the simplicity of set up and tuning of the loop through modifying the proportional and/or integral gains K.sub.p, K.sub.j by a linear or parabolic function of the feedback error signal. Provision is made for symmetrical or asymmetrical gain modification functions.

Abstract: An apparatus has a mass suspended between two mounting plates by a separate springs to form a resonant structure that absorbs vibration in a structural member to which the mounting plates are attached. Permanent magnets are fixed to opposite sides of the mass. A sensor produces a signal indicating the frequency of the vibration. A feedback circuit receives the signal from the sensor and produces an output signal having first component frequency which corresponds to a harmonic of the frequency of the vibration. The output signal is applied to a separate voice coil adjacent to each permanent magnet. The magnetic fields produced by the output signal flowing through the voice coils interact with the magnetic fields from the permanent magnets to generate forces that act on the mass in a manner that increases the impedance of the absorber to the vibration in the structural member.

Abstract: An electrical drive control system includes a controlled drive, an auxiliary generator, a control unit, and a power unit. The rotors of the controlled drive and of the auxiliary generator are connected so that rotation of controlled drive causes a corresponding rotation of the auxiliary generator. The control unit receives a first reference signal having a first frequency. The auxiliary generator receives a second reference signal having a second frequency. The control unit may generate the second reference signal. In response to the second reference signal, the auxiliary generator generates a primary information signal having a phase shift that is indicative of the rotational position of a rotor of the auxiliary generator and the controlled drive. The control unit receives a user selected position command indicative of a selected position of the rotor.

Abstract: A motor drive control apparatus has a number of revolution setting circuit, a driving circuit for driving a motor to rotate at a predetermined number of revolution based on a number of revolution command signal output from the number of revolution setting circuit, a number of revolution detecting circuit for detecting the number of revolution of the motor, a driving voltage adjusting circuit for adjusting a level of the driving voltage of the motor to be supplied to the driving circuit, a motor control circuit including a PLL control circuit for controlling the number of revolution of the motor so that the phase difference between the phase of the number of revolution command signal and the phase of the number of revolution detection signal becomes within a predetermined range of value, and a voltage control circuit for instructing the driving voltage adjusting circuit to adjust the driving voltage of the motor to be at a level in the vicinity of the PLL controllable minimum level.

Abstract: An improved servo control device and method for a VCR that minimizes jitter caused in a reproducing mode of the VCR (reproducing VCR) when it reproduces a video signal recorded by another VCR (recording VCR). A recording characteristic of the recording VCR (such as a duty interval of horizontal synchronous signals contained in the video signal) is used along with one or more reproducing characteristics (such as speed and phase) of the reproducing VCR to control a rotation speed of the reproducing VCR's drum motor.

Abstract: The oscillating mechanical device comprises a shaft on which an oscillating member is mounted, and which is resiliently urged towards a middle angular equilibrium position, together with a single-phase induction motor whose rotor is coupled to the shaft so as to enable oscillations of the shaft to be sustained. According to the invention, the stator of the single-phase induction motor is fed with an alternating drive signal whose frequency is adjusted to the vicinity of the natural frequency of oscillation of the mechanical device. More particularly, the frequency of the drive signal of the stator is set to lie in the frequency range ?f-0.8 Hz; f+0.1 Hz!, where f represents the natural frequency of oscillation of the mechanical device, and is preferably set to the natural frequency of oscillation of the mechanical device with a tolerance of plus or minus one-tenth of one hertz. The device is applicable to card web combs used in the textile industry.

Abstract: In order to start a brushless motor, a frequency setting circuit sets a frequency value, a counter increases a count value in response to a main clock signal, and a comparator compared the value of the frequency setting circuit with that of the counter and resets the counter when the compared values are the same. A circuit is also provided for changing the frequency value of the frequency setting circuit to a high frequency value in response to an output signal of the comparator and a back electromotive force detection signal.

Abstract: A rotation position detecting circuit for a sensor-less motor and a motor device include a motor (1) which is rotated and driven by adding a sensor signal having a high frequency to a sine wave drive signal and cosine wave drive signal through adders (5S) and (5C), respectively. Further, a sensor signal is extracted and demodulated from a signal flowing in the motor (1) by a band pass filer (9), and this is defined as a rotation position detection signal. In the sensor signal from the band pass filter (9), its current value is changed corresponding to a change of an impedance resulting from a rotation of a magnet of the motor. As a result, it is possible to detect the rotation position of a rotor magnet by detecting the change of the current value.

Abstract: A frequency-locked stepping position control servo (FLSPS) system for driving a stepping motor. It essentially comprises a means for driving the stepping motor to move an object toward a target according to a driving signal, a means for detecting position of the object, a position-to-frequency converter to feedback the position information and a microprocessor-based slope-varied frequency-controlled oscillator (.mu.P-SVFCO) to generate the driving frequency. The .mu.P-SVFCO includes a microprocessor to ease the implementation of the control law and utilizes the slope-varied technique to adaptively pump the pulse train frequency of the driving signal. In addition, a one-bit clock is provided to dynamically maintain the position of the object when the target position is reached. The FLSPS system is capable of achieving similar system acquisition times for different target commands among a wide-range of positioning control commands.

Abstract: Excitation signals having a phase difference of 120.degree. are generated based on a count of a ring counter and they are supplied to a phase detection type resolver. An output of the resolver is compared with zero level by a comparator to generate uncorrected position data .theta..sub.F which is supplied to a digital delay circuit to delay it in accordance with a position correction value .DELTA..theta. from a position correction ROM to generate corrected position data .theta..sub.B. The corrected position data is supplied to a latch circuit which latches a count of a ring counter and a velocity detection circuit to produce resolver position data .theta..sub.P and velocity data .DELTA.T, which are added and the sum is supplied to the position correction ROM as address data. The velocity data .DELTA.T is converted to a pulse by a pulse generator and it is accumulated by an accumulation counter to detect a position of a moving part.

Abstract: A motor control circuit generates a signal representing a rotation frequency of a motor. It produces a motor speed error signal based on the rotation frequency. The error signal is changed by a speed gain circuit and supplied to the motor driving circuit through a filter. The filter is for preventing an oscillation in a servo loop. When the motor speed is out of a predetermined range, a gain of the speed error signal is reduced and the filter is disabled.

Abstract: A servo control apparatus for controlling a rotation speed of a motor such as a capstan motor or a drum motor for a video tape recorder. In the servo control apparats, a control value generating unit generates a control value on the basis of a difference between the rotation speed of the motor detected by a rotation speed detecting unit and a desired value of the rotation speed. When a deviation value representing a difference between the control value generated by the control value generating unit and an ideal control value representing an ideal value of the control value is constant for a predetermined period of time, an error state monitoring unit outputs the deviation value. An adding unit adds the control value generated by the control value generating unit with the deviation value to obtain a result of addition, and a drive voltage generating unit drives the motor by a drive voltage according to the result of addition from the adding unit.

Abstract: The disclosed hunting suppressor is for use with n-phase electric motors including a stator having n windings and a rotor. The hunting suppressor is responsive to a reference clock signal characterized by a frequency f.sub.c and an associated phase angle .phi..sub.c.A controlled frequency oscillator generates n drive signals, where the drive signals are mutually shifted in phase by 180/n degrees. The drive signals are each coupled to drive a respective one of the n windings of the motor. A phase locked loop network locks the frequency and phase of one of the drive signals to that of an applied clock reference signal. With that configuration, the rotor is controlled to rotate at the frequency of the clock reference signal with substantially no hunting.

Abstract: A motor controller of the present invention has a frequency generator which outputs, in accordance with a rotation of the motor, a predetermined number of rotational signals every time the motor makes one rotation. A period signal representative of the period of the rotational signals is calculated, and the period signal and a predetermined value are subtracted to obtain a speed error signal. The error signal is stored at a predetermined address of a memory. A filter which performs filtering by use of a plurality of error signals in the memory and a subtracter which subtracts the error signals and the contents of the memory are provided. A selecting circuit outputs the error signal when the error signal is outside a predetermined range and outputs an output of the filter when the error signal is within the predetermined range. Thereafter, the selecting circuit outputs an output signal of the subtracter. A control signal is produced from an output of the selecting circuit.

Abstract: A method and apparatus to be used with the motor controller for reducing phase shift between the feedback signal and the correction signal. Wherein the feedback signal is compared by the controller to a reference signal to provide the correction signal used to alter motor control signals. The method includes changing a correction signal according to a transfer function to produce a filter signal wherein the transfer function includes two variables: k.sub.n and .omega..sub.n, .omega..sub.n always being greater than zero, and k.sub.n being negative when the feedback signal is phased shifted into a medium frequency range. The method and apparatus produce filtered signals that are phase shifted and amounts determined by the k.sub.n and .omega..sub.n variables. Where k.sub.n is negative, the filtered signal is phase lagged by an extreme degree.

Abstract: A speed control system is disclosed wherein a brushless DC motor and a magneto resistive encoder are able to rotate a motor at arbitrarily low speeds. The motor is able to rotate at low speeds by having a filtered signal generated by an encoder applied to its inputs. The encoder is coupled to a series of filters which remove DC level and harmonic distortions from the resulting encoder signal. These filtered signals are then applied to the motor to control motor rotation speed.

Abstract: A servo motor control circuit for a video signal playback apparatus including a wave-shaping circuit, a speed error detector, a first filtering circuit for filtering torque ripple components of servo motor speed error signals characterized in that the gain in much higher in a low frequency band than in any other frequency band, a second filtering circuit for attenuating the low frequency gain of signals output from the first filtering circuit, a phase error detector, an adder, and a motor controller, resulting in a decrease in low frequency band phase distortion and a decrease in the time required for servo motor stabilization.

Abstract: A spindle motor controlling circuit for controlling the rotation of an optical disk system using a constant linear velocity servo. The circuit includes a spindle motor rotation sensing circuit for generating a phase frequency in response to the rotation of the spindle motor. A speed control part of the controlling circuit includes a speed error signal generating circuit that generates speed error data indicative of a difference between the period of the phase frequency and data representing a desired spindle motor speed. A phase control part of the control circuit includes a phase coefficient pulse generating circuit, a reference phase signal generating circuit and a phase error signal generating circuit. Finally, the controlling circuit includes a driving voltage generating circuit for generating a speed driving voltage corresponding to the speed error data and a phase driving voltage corresponding to the phase error signal. The driving voltages are used for driving the spindle motor.

Abstract: A method and circuit for implementing a frequency lock loop circuit in a disk drive is disclosed. The circuit includes the motor control elements of a direct current motor plus a coarse counter, a fine counter, and a digital to analog converter. The coarse counter is used to count down from a programmed coarse count. The fine counter begins to count down from a fine count when the coarse counter reaches zero. The count in the fine counter, when a zero crossing occurs, represents the difference between the expected period and the actual period and is loaded into a digital to analog converter which converts the difference to an analog voltage which is used by the coil drive circuit to either speed up or slow down the motor. The digital to analog conversion may be realized by a charge pump circuit.

Abstract: A parameter identifier which estimates parameters of a plant includes a model, a subtracter, a delay circuit, and a parameter adaptive mechanism. Disturbances are assumed to be represented by an impulse train consisting of a finite number (=m) of impulses. The model estimates n state variables and the output of the plant on the basis of the input and output of the plant. The subtracter outputs the error between the output of the plant and the estimated output. The delay circuit delays the state variables outputted from the model by N (.ltoreq.n+m+1) samples before applying them to the parameter adaptive mechanism. The parameter adaptive mechanism calculates the parameters on the basis of the products of the error and the delayed state variables. The number N is determined such that the effect of the disturbance on the error disappears in N samples from the beginning of the disturbance.

Abstract: A servo system controller for a disk drive device which includes a rotating mass storage disk incorporates a timing error determining circuit for determining rotational speed variations in the disk from information contained in a servo field recorded in a track. A timing error signal is supplied when the speed variation exceeds a threshold, thus indicating an unacceptable level of speed variation. A digital synchronizer responds to asynchronous servo data signals from the disk to establish a cell clock signal occurring about a normal frequency, a cell during which only one servo data signal will occur, and a cell data signal which occurs during the cell. The cell clock signal clocks logical operations on a synchronous basis, and servo data signals are reliably captured.

Abstract: A media transport system for controlling the position and velocity of media in a document production apparatus marking engine having a media positioning system driven by a motor, includes a motion control loop to control the motor; a sensor adapted to detect the position of the media and to create a trigonometric signal characteristic of the position of the media, the trigonometric signal comprising frequency and phase components; a resolver electronics subsystem adapted to trigonometrically process the trigonometric signal to create a resolved signal; and means for comparing the resolved signal to a reference clock signal of predetermined frequency and phase to provide an error signal used to control the motor that drives the media positioning system. The trigonometric signal may include a sine portion and a cosine portion. The sine portion of the trigonometric signal is sin(.omega..sub.e *t+.phi..sub.e) and the cosine portion of the trigonometric signal is cos(.omega..sub.e *t+.phi..sub.e); where .omega..

Abstract: A speed control apparatus for a motor has a driver for the motor. The motor's rotational speed is detected, and a signal from the detector is counted. Signals from the counter received as the input by another circuit, which outputs data representing irregularities in the detection signal once the motor has reached its constant speed. Correction information is supplied to the motor driver on the basis of the irregularity data.