Abstract: An electric power steering apparatus which comprises: an angle detector for outputting a sine wave signal and a cosine wave signal corresponding to a rotor position of a brushless DC motor; and a torque detector for detecting a steering torque applied to a steering member, and which drives the brushless DC motor to assist steering based upon the sine wave signal and the cosine wave signal which were outputted from the angle detector and the steering torque detected by the torque detector. A sine wave signal and a cosine wave signal are squared and added to each other, and whether or not abnormality has occurred in the angle detector is detected by whether the addition result falls within a predetermined range. It is possible to detect abnormality in the angle detector at an early stage.

Abstract: A servo driver (3) includes: an input section (11) for input-specifying the type of an encoder (7) at the side of an actuator (2); a control section (13) for generating a control signal (12) according to the type input; and an encoder signal processing IC (20) for switching the input port to which reception data (7S) is input form the encoder (7) according to the control signal (12). The encoder signal processing IC (20) is compatible with processing of an output of either a line-saving encoder or a 14-line encoder and can realize a highly general-purpose servo driver. This can solve the problem that the servo driver should be modified according to the type of the encoder mounted on the actuator.

Abstract: A vibration controller controls vibrations generated in a driven object included in a system subject to vibrations due to the dynamic unbalance or eccentricity of a rotating member driven for rotation by an electric motor. An angular position transforming unit (45) and an angular velocity transforming unit (47) transform the output signal of a rotating motion measuring means (C1) into an angular position and an angular velocity, respectively. A sine calculating unit (55) calculates the sine of an angle obtained by adding up the angular position and a predetermined phase angle provided by a phase adjusting unit (49) by an adder (53). A multiplier (61) calculates the product of the output of a gain adjusting unit (57) that multiplies the output of the sine calculating unit (55) by a predetermined gain and the output of a multiplier (59) that calculates the square of the angular velocity. Again adjusting unit (57?) multiplies the output of a sine calculating unit (55?) by a predetermined gain.

Abstract: A control device measures time intervals T1 to T12 from the reference time until when each of the rotational angles ?bn1, ?bn2 output from each of resolvers becomes n×60 degrees (n=1 to 12, i.e., 60 degrees to 720 degrees). Then, the control device calculates a deviation angle ??n at each of the rotational angles at the intervals of 60 degrees by calculating T1/T12 to T11/T12 using the measured T1 to T12. By substituting the calculated deviation angle ??n into an equation, n×60°+??n (n=1 to 11), the control device corrects the rotational angles at the intervals of 60 degrees. The control device generates each of drive signals DRV1, DRV2 using each of the corrected rotational angles, and outputs each of the drive signals DRV1, DRV2 to each of inverters. The inverters drive each of AC motors (M1, M2) based on each of the drive signals DRV1, DRV2.

Abstract: This invention provides an electrically-powered steering apparatus capable of assisting a steering torque appropriately using a resolver. A reference signal is applied to a resolver arithmetic processing I/F circuit 34 and a resolver arithmetic processing I/F circuit 36 through a reference signal input means 38 and a microcomputer 30 obtains a differential in amplification factor from outputs of the resolver arithmetic processing I/F circuit 34 and the resolver arithmetic processing I/F circuit 36 when the reference signal is supplied. A correction value for computing a position from the outputs of the resolver arithmetic processing I/F circuit 34 and the resolver arithmetic processing I/F circuit 36 is computed from the obtained differential.

Abstract: A region judging circuit judges an electric angle region of a three-phase brushless DC motor based on an output signal of a resolver. A latch timing output circuit determines an optimum latch timing. A driving direction judging circuit judges a rotational direction of the motor based on a comparison in largeness between a pair of phase currents. A latch circuit latches a judgement result of the driving direction judging circuit at the latch timing designated by the latch timing output circuit and retains the judgement result until the next latch timing comes.

Abstract: A programmable limit switch includes output channels for receiving position data, each position value of the position data representing an incremental advance of a workpiece through a production field, and for producing actuation signals. The channels are connectable to respective output devices responsive to the respective actuation signals and located in the field. Each output channel has an output controller, which is individually programmable to change the state of respective actuation signals in response to reaching selected position values. Preferably, the PLS includes input connectors coupled to a respective channel and connectable to respective input devices located within the production field. Each channel operates its own inputs and outputs according to a variety of programmed functions depending upon system conditions seen by the output controller.

Abstract: A rotor transformer positioning mechanism permitting automatic positioning of a rotor transformer, having a first winding, relative to a rotor stack, having a second winding, mounted on a common rotary shaft to thereby permit a crossover having a predetermined length to be installed between the first and second windings includes a crossover positioning cutout disposed in a first flange of the rotor transformer. In an exemplary case, the rotor transformer includes the first flange and a second flange disposed on opposite ends of the first coil, and the second flange is proximate to the crossover. A method of assembling a rotating machine using the rotor transformer positioning mechanism is also described.

Abstract: A method of controlling a rotational velocity of a rotatable member during initialization of an analog encoder unit that generates a channel A signal and a channel B signal, includes the steps of processing the channel A signal and the channel B signal to generate a feedback signal, an integrity of the feedback signal being maintained even if only one of the channel A signal and channel B signal is functional; and controlling the rotational velocity of the rotatable member during the initialization of the analog encoder unit based on the feedback signal generated by processing the channel A signal and the channel B signal.

Abstract: A resolver phase calibration system comprises a reference pulse generation unit, a resolver-to-digital converter (RDC), and a calibration phase calculating unit. The reference pulse generation unit is configured to generate a reference pulse signal based on a back electro-motive voltage signal of a motor. The RDC is configured to convert output signals of a resolver to a pulse signal, to count pulses of the converted pulse signal, and to output a digital output signal corresponding to a number of the pulses. The calibration phase calculating unit is configured to calculate a calibration phase of the resolver based on the reference pulse signal from the reference pulse generation unit and the digital output signal from the RDC.

Abstract: The present invention relates to a method and a circuit using the method thereof for minimising the phase errors during the driving of an electric motor, and a circuit using the method thereof, having a stator winding, a permanent magnet rotor assembly, and devices able to sense a rotor position, which comprises the following steps: a) generating of a rotor position signal (10, 14, 39), by means of said devices able to sense said rotor position; b) detecting at least two information from at least two edges (11, 12; 15, 16) of said rotor position signal (10, 14, 39) inside a measure period; c) generating a driving signal (9, 13, 38), in function of said at least two information (11, 12; 15, 16) inside the measure period, so as to follow the rotor velocity.

Abstract: A motor for reducing torque ripple includes a shaft having a shaft axis, a rotor positioned about the shaft, a first magnet ring positioned on the rotor, the first magnet ring having magnets each occupying a magnet angle &dgr; on the rotor, and a second magnet ring positioned on the rotor, the second magnet ring having magnets each occupying a magnet angle &dgr; on the rotor, wherein the second magnet ring is shifted a non-zero number of degrees relative to the first magnet ring and wherein ends of each magnet within the second magnet ring are located at different angular positions than ends of each magnet within the first magnet ring relative to the shaft axis of the shaft. The magnet angle &dgr; is preferably an optimal magnet angle for minimizing cogging torque and line to line back emf harmonics.

Abstract: A method for utilizing a three-wire programming box with a motor control circuit is provided. The method includes providing a three-wire to two-wire interface. The method further includes connecting the three-wire to two-wire interface between the three-wire programming box and the motor control circuit such that the three-wire programming box communicates bi-directionally with the motor control circuit utilizing less than three connections between the three-wire to two-wire interface and the motor control circuit.

Abstract: A current target angle stored in a target angle register is subtracted from the immediately preceding target angle stored in a register by a subtracting device. As a result, the length (amount) and direction between the immediately preceding target angle to the current angle are generated. With the generated length and direction, a model acceleration generating circuit generates model acceleration data. With a count value of a current velocity detecting counter and a velocity data sequence that is output from a model velocity generating circuit, velocity error data is generated. With a count value of a current position detecting counter and a position data sequence that is output from a model position generating circuit, position error data is generated. The model acceleration data, the velocity error data, and the position error data are added by an adding device. The added result is supplied to a driver. The driver outputs a current that drives a pan motor.

Abstract: A motor controller (30) includes three analog Hall-effect sensors (42, 44, 46) for forming continuous-time signals proportional to the sine and cosine of the position of the rotor (24) of a motor (20). The sine and cosine signals are differentiated to obtain signals proportional to the rotor rate times the sine and cosine values. These integrated values are then multiplied by the cosine and inverse of the sine values, respectively, to obtain values equal to the rotor rate times the square of the cosine and the rotor rate times the square of the sine. These latter two values are summed to obtain an output signal proportional to the rotor rate based on the trigonometric identity sin2(x)+cos2(x)=1. Since the motor controller (30) derives a high-resolution value for the rotor rate, it may be used for fine resolution control of brushless motors and the like.

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: A digital signal processor for closed loop velocity or position control receives sine winding output signals and cosine winding output signal from a resolver, digitizes the signals and outputs quadrature encoded signals to an excitation circuit. The excitation circuit is connected to an excitation winding in the resolver to provide signals for driving the resolver.

Abstract: A position detecting apparatus includes: a position sensor 10 that inputs an excitation signal having a given period waveform and outputs a first amplitude modified signal induced in accordance with a detected position from a first output winding and outputs a second amplitude modified signal induced in accordance with a detected position from a second output winding; a first phase shifting circuit 23 for electrically shifting a phase of the first amplitude modified signal by a given angle; a second phase shifting circuit 24 for electrically shifting a phase of the second amplitude modified signal by a given angle; converting means 15,16 for converting the signal outputted from the first phase shifting circuit 23 and the signal outputted from the second phase shifting circuit 24 into a phase modulated signal; and calculating means 17-22 for obtaining a detected position on the basis of the phase of the phase modulated signal outputted from the converting means 15,16.

Abstract: A resolver (20, 21) is provided with redundant excitation windings in which only a single excitation winding (E1) is energized externally. Cross coupling from the externally energized winding (E1) excites the other excitation winding (E2). A control circuit (27, 28) monitors the excitation of the redundant excitation winding (E2) and switches the excitation to the redundant excitation winding (E2) in the event of a failure of the externally winding (E1).

Abstract: An improved resolver permits the outer periphery of a ring-shaped stator and the inner periphery of a ring-shaped rotor to be directly exposed by eliminating the use of a case and a hollow rotating shaft to thereby reduce the outside diameter of the resolver as a whole. This arrangement overcomes the difficulty of reducing the outside diameter of a prior art resolver due to a case disposed to the outer periphery of a ring-shaped stator and a hollow rotating shaft disposed to the inner periphery of a ring-shaped rotor.

Abstract: A resolver system and method is provided for determining the angle position of a shaft. The resolver system includes a resolver having first and second output windings and an input or reference winding spaced apart from the first and second output windings, where either the input winding or the output windings are connected to the shaft. When a drive signal is introduced into the input winding, it generates first and second output signals on the output windings representing the angle position of the shaft. The resolver system of the present invention further includes a processor connected to the output windings for receiving the first and second data signals from the resolver and determining the angle position of the shaft. For generating the drive signal, the resolver system further includes a drive circuit connected to the input winding of the resolver. The drive circuit generates a pulsed drive signal for input into the resolver.

Abstract: It is assumed that an element to be detected 2a in a position sensor is mounted on a rotary shaft with the center O′ of the element to be detected eccentric from a center of rotation O by a distance d. When the rotary shaft is rotated at a fixed speed, the positions at angles 0° and 180° are accurately detected by a sensor 2b, while the positions at angles 90° and 270°, the sensor detects the positions P1′ and P3′, instead of P1 and P3 which are originally to be detected, resulting in undulation of detected positions as shown in FIG. 3(b). The peak value of the unduration and an angle of rotation at which the peak value is found are determined.

Abstract: In a procedure for the digital evaluation of the analogue output signals from a resolver with at least two stator windings, arranged perpendicular to each other on a stator, and at least one rotor winding on a rotor able to rotate in relation to the stator, a sinusoidal signal is applied to the rotor winding and sine, respectively cosine shaped signals, depending on the angular position of the stator in relation to the rotor, are extracted from the stator windings. These signals are further processed after conversion into digital signals by application of the inverse tangential function, in order to compute an angular value for the relative angular position between the rotor and the stator. This angular value is affected by a propagation delay time error, which is compensated for by the introduction of a control loop.

Abstract: An electronic cam servo apparatus uses a digital servo controller to perform motion equivalent to a mechanical cam. The control apparatus has one data table representing a characteristic of a mechanical cam and utilizes a data interpolation and the first derivative of a cam position profile to determine position and velocity commands to drive a servo motor which performs motion equivalent to a mechanical cam. Alternatively, the control apparatus uses the first cam specific data table to determine the position, velocity and torque/current command to drive a servo motor. The apparatus may additionally use a second data table representing varying cam load to obtain a more accurate torque/current command correction.

Abstract: A servo control apparatus for performing a feedback control to an analog controlled system, includes an error generating device that generates a digital error corresponding to a difference between a desired value and a feedback value corresponding to a controlled variable of the analog controlled system, a control device that generates a digital manipulated variable, and a digital-to-analog converting device that converts the digital manipulated variable into an analog manipulated variable for driving the analog controlled system. The control device includes a disturbance estimating device that estimates a disturbance applied to the analog controlled system by carrying out a digital estimating process by using the digital manipulated variable and the digital error and generates a digital compensated variable corresponding to the estimated disturbance, and a manipulated variable generating device that generates the digital manipulated variable by using the digital error and the digital compensated variable.

Abstract: A resolver comprises excitation windings for receiving excitation signals and a detection winding for outputting a detection signal. Displacement of a passive member provided with the excitation windings or the detection winding is detected on the basis of the detection signal which varies with the displacement of the passive member. A modulated signal obtained through modulation of a high-frequency signal by an excitation signal is input to each of the excitation windings, and a detection signal is obtained through demodulation of a modulated signal output from the detection winding. Since the modulated signal obtained through modulation (amplitude modulation) of the high-frequency signal by means of the excitation signal is applied to the excitation windings, the number of turns in the excitation and the detection windings can be reduced.

Abstract: A method and an apparatus for driving a stepping motor is provided. Digital desired current values are stored in the form of a sine table and are read from the sine table at a constant sampling frequency. The intervals between the read-out table values can be varied equally and unequally. The digital desired current values are converted into discrete analog signals. A sinusoidal signal is reconstructed from the analog signals. A motor current for exciting a phase of the stepping motor is derived from the sinusoidal signal.

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 resolver (10) is excited with a high frequency signal from excitation circuit (16). Outputs of the resolver (10) are transmitted through receiver circuit (24) and input to a DSP signal processing circuit (18), which demodulates the sine and cosine outputs to provide samples of the sine and cosine of the rotor position. The sample values are converted to digital values, which are used to calculate a shaft angular position, which is then used for closed loop position and velocity control of a brushless PM motor (14).

Abstract: A brushless AC servo motor control and modified motor to minimize the rotational acceleration and deceleration of a semiconductor wafer during processing steps where fluid is applied in a thin coating on the wafer. The control utilizes sine and cosine encoder outputs of single cycle and multiple cycle per revolution to calculate motor shaft position by an inverse tangent calculation of sine and cosine ratios. Resolution of motor shaft position is greatly improved as is rotational velocity control. In response to a prediction of desired shaft position in comparison with actual position the three field currents are adjusted to change the torque applied to the rotor and shaft. In the semiconductor wafer manufacturing application the motor shaft is modified to permit vacuum attachment of the wafer to the disc that rotates with the shaft.

Abstract: A slip controlled induction motor using a variable frequency feedback transducer comprises a motor stator, a motor rotor and a variable frequency feedback transducer (VFFT). The VFFT includes an input winding transformer coupled to an output winding by a VFFT rotor. The VFFT rotor is operably connected to the motor rotor so as to rotate with the motor rotor at the same angular velocity. The input winding is excited with an input AC voltage of predetermine frequency. The transformer coupling combines the predetermined frequency AC input with the signal produced by the VFFT rotor to produce a variable frequency signal in the output winding which is fed as an input to the motor stator. Since the stator input is tied to the motor rotor angular velocity, the stator input will always have a constant absolute frequency difference with the motor rotor.

Abstract: A converter circuit for converting an alternating signal representing continuous rotary position into a further signal representing discrete rotary position samples the polarity of an envelope of the alternating signal and develops a state change in the further signal when the envelope changes polarity.

Abstract: A method of controlling a rotary magnet multi-phase synchronous motor and a control system based on this method increases the permissible range of accuracy in installing a position detector on the synchronous motor and automatically calculates a phase correction to improve controllability. Using a position detector for detecting a magnet position of a rotary magnet multi-phase synchronous motor and a drive unit, the synchronous motor having the position detector is driven by a drive unit. After the synchronous motor reaches a constant speed, current and drive voltage of the synchronous motor are measured to calculate a phase correction value between a biaxial coordinate axis based upon the installation error of the position detector and a biaxial coordinate system from conversion of a polyphase AC coordinate system based on the measured current and drive voltage, constants of the synchronous motor, and the constant speed.

Abstract: A stator wound resolver comprising: a stator and a rotor aligned on an axis; the stator having a plurality of teeth with input and output windings disposed on some or all of the teeth, the input and output windings exhibiting a mutual inductance characteristic that varies as a function of position of the rotor about the axis; the input winding being connectable to a drive signal and the output windings being disposed on the teeth such that output signals induced in the output windings correspond to position of the rotor; the rotor being attachable to a position changing means, the rotor comprising at least two axially spaced rotor pieces that are offset from each other by a stagger angle such that a portion of harmonic distortion produced by one of the rotor pieces is reduced by complementary harmonic distortion produced by another of the rotor pieces.

Abstract: In a motor control apparatus for controlling a rotational position of a motor, a rotation detector detects the rotational position of the motor, and outputs first and second detection signals having phases corresponding to a detected rotational position of the motor and different from each other, and a position detecting circuit detects a rotational position in a unit which is less than one cycle of the first and second detection signals based on the first and second detection signals, and outputs a rotational position signal representing a detected rotational position. Further, a motor controller compares the rotational position signal with a reference position signal representing a reference rotational position of the motor to obtain a position error, and controls the rotational position of the motor so that the position error is minimized.

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 pulse excitation circuit applies a constant voltage to windings, each of which is wound around a respective one of four magnetic poles of a resolver stator. In each of the respective windings, a voltage is generated corresponding to the rotation of the resolver rotor. From the generated voltage, it is possible to detect two flows of electrical currents which have different phases from each other. Values of the electrical currents after a lapse of time 2*Lav/r from the start of pulse excitation (Lay is an average inductance of the windings, while r is a DC resistance of a winding, including an electrical current detection resistance) are converted into two digital values. A micro computer calculates a rotation angle signal .theta. on the basis of the two digital values.

Abstract: A controller for force compensation in a variable reluctance motor includes a sensor coupled to the variable reluctance motor for obtaining instantaneous motor position data and a controller coupled to the sensor for receiving the instantaneous motor position data and desired force command. The controller includes a circuit for comparing the instantaneous motor position data and the desired force command with a plurality of stored data points. Each stored data point represents a phase current value. The comparing circuit identifies a selected stored data point having position and desired force command values numerically closest to the instantaneous motor position data and the desired force command. The controller also includes a circuit for interpolating a desired phase current value based on the phase current value of the selected stored data points; a circuit for generating a current having the desired phase current values; and a circuit for outputting the current to the variable reluctance motor.

Abstract: A robust angle-position sensor for the absolute measurement of the angle of rotating or angle position, respectively over several revolutions has a resolver and further inductive angle of rotation sensor elements. Switching elements of a time multiplex device are in the form of toroidal core chokes. The electronic processing circuit is arranged at a point remote from the point of measurement.

Abstract: An angle of rotation detector has a drive unit which supplies 90 degree phase shifted signals to a pair of stator coils and measures an analog output from a rotor coil in a resolver. A calculating device calculates the rotational angle of the resolver using the output of an analog to digital converter receiving the analog output of the rotor. In one embodiment, the calculating device performs a Fourier transform to compute the phase of a fixed frequency component contained in the output of the rotor coil. In another embodiment, the drive unit supplies signals wherein f(T/2+t)=-f(t) and the calculating device performs a Fourier transform using data from successive half periods of the drive waveform. In another embodiment, the output of the rotor is sampled at 1/4 period of an excitation signal from the drive unit and the calculating device determines the phase difference between the excitation signal and the rotor output.

Abstract: Disclosed is a high accuracy angular position transducer of simple constuction. The angular position transducer consists of a stator core in slots of which both exciting windings with p .sub.1 pole pairs and output windings with p .sub.2 pole pairs are wound, and a rotor core which carries no windings and has salient poles whose number is an integer N satisfying one of the following relations, p.sub.1 +p.sub.2 =N, or p.sub.1 -p.sub.2 =.+-.N. In this construction the angular position is detected by using the following voltages induced in output windings: two or three phase voltages having a sinusoidal waveform of one cycle per rotation of 1/N of the circumference, in the combination of single phase exciting windings and two or three phase output windings; single phase voltage having a sinusoidal waveform whose phase shifts by 2.sub..pi. per rotation of 1/N of the circumference, in the combination of two phase exciting windings and single phase output windings.

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: Positioning errors of a moveable machine member are reduced by compensation for cyclic errors attributable to anomalies of a position transducer. Compensation values are produced which are unique only within the pitch of transducer measurement and are applied to correct the representation of measured position produced by the transducer. Positioning errors not attributable to the position transducer are corrected by compensation of position commands using compensation values associated with fixed calibration points. Use of both compensations is effective to eliminate residual errors in position correction which arise from use of calibration data created without correction of transducer cyclic errors.

Abstract: An improved robotic arm system for servicing the tubesheet located within the channel head of a nuclear steam generator is provided. The system includes a robotic arm whose shoulder and elbow joints are rotatable only in the plane parallel to the tubesheet in order to eliminate the imposition of cantileverly-induced torques on the electric motors driving these joints, as well as to minimize the possibility of mechanical interference between the arm and the walls of the channel head. Each of the motorized joint assemblies of the arm includes resolvers connected not only to the output of the drive train that moves the joint, but also to the drive shaft of the electric motor that drives the drive train, wherein the feedback signal generated by the resolver connected to the drive shaft of the electric motor is the primary signal used to modulate the amount of electric power conducted to the motor of the joint. Such a configuration advantageously results in smoother robotic arm movement.

Abstract: A printing cam is rotated forward from a print starting position by a motor in a printing operation. Then, a print hammer is driven in association with a cam follower driven by the printing cam, so that a printing operation is executed. An encoder disk is disposed so as to rotate integrally with the printing cam. A plurality of slits are disposed in an equidistantly spaced relationship in an encoder disk. A phase setting portion is provided in the encoder disk as a reference position for providing a rotational position of the encoder disk. The phase setting portion is an interval between two specific slits, the interval being formed by enlarging the interval between two slits. While the encoder disk rotates forward, a slit counter executes an additional operation every time a photosensor detects a slit. While the encoder disk rotates reversely, a slit counter executes an subtractional operation every time the photosensor detects a slit. After the printing operation is ended, the motor rotates reversely.

Abstract: A variable reluctance resolver comprises a rotor core and stator magnetic poles structured to enable reluctance in the space between the rotor core and stator magnetic poles to be changed by the positions of the rotor core and to make the fundamental wave component of the reluctance variation N cycles per revolution of the rotor core, N being an integer of 1 or more; first magnetic poles having a predetermined number 3N phases arranged at equal intervals on the stator magnetic poles; second magnetic poles having a predetermined number of 3N phases formed in the central positions between the first magnetic poles; excitation coils arranged individually between the first and second magnetic poles and connected in series to each other for each phase of the magnetic poles; a current change detecting device for detecting current value change due to the variation of the reluctance when an alternating current is applied to the magnetic coils of each phase of the magnetic poles; 3N difference value calculating devices

Abstract: An auxiliary resolver position tracking (RPT) system for an industrial robot includes a resolver excitation and monitoring system which is powered by an uninterruptable power supply which includes a battery. The RPT system generates trapezoidal excitation pulses for the resolvers in the robot when no external excitation signal is applied, for example when the robot is shut down. Since there is relatively little motion to be detected in these instances, the RPT system switches between a slow position sampling rate, when no motion is detected, and a fast sampling rate when motion is detected. When operating on battery power, the RPT only switches to the fast sampling rate when motion is detected. To ensure that no motion data is lost when the system switches back to the slow sampling rate, the high sampling rate is maintained for a time sufficient to capture any residual motion of the robot.

Abstract: An auxiliary resolver position tracking (RPT) system for an industrial robot includes a resolver excitation and monitoring system which is powered by an uninterruptable power supply which includes a battery. The RPT system generates trapezoidal excitation pulses for the resolvers in the robot when no external excitation signal is applied, for example when the robot is shut down. Since there is relatively little motion to be detected in these instances, the RPT system switches between a slow position sampling rate, when no motion is detected, and a fast sampling rate when motion is detected. When operating on battery power, the RPT only switches to the fast sampling rate when motion is detected. To ensure that no motion data is lost when the system switches back to the slow sampling rate, the high sampling rate is maintained for a time sufficient to capture any residual motion of the robot.

Abstract: A resolver system includes a resolver having an annular rotor, and an annular stator arranged around the annular rotor in spaced relationship thereto. The rotor and the stator are arranged such that the reluctance of a space defined between the rotor and the stator varies with a change in the angular position of the rotor in such a fashion that one revolution of the rotor causes one cycle of a fundamental frequency component of variation of the reluctance.The stator has formed thereon a plurality of pole shoes circumferentially arranged at intervals of 120.degree. or 60.degree. to form three of six phases, each of the pole shoes having a single kind of winding wound thereon. A servo driver applies an excitation signal to each of the windings on the pole shoes of the stator to excite same.

Abstract: A method and apparatus are provided for measurement of absolute position of a moveable machine member wherein output signals of a plurality of position measuring devices are selectively connected to an interface circuit. Each position measuring device produces output signals representing relative position of a device armature and device stator. The position measuring devices are coupled to the machine member so that the absolute position of the machine member anywhere within its range of motion may be uniquely determined from the output signals. A control signal is produce to control the selection of the output signals to be connected to the interface circuit which, at any instant, receives the output signals of a single position measuring device.