Abstract: A device for controlling plural loads with phase locked loop control method by means of reference signals of different phases in order to avoid peak in electric power consumption.

Abstract: A position/speed detection method and apparatus employing an encoder mounted on the rotary shaft of a motor in order to control the position and speed, wherein the coarse position and fine position are simultaneously detected by an encoder pulse and an encoder original signal, respectively and the detected results are combined to detect the position and speed of the motor with high precision.

Abstract: A phase detection control apparatus is disclosed for detecting any variable where the phase is discretely measured, as for example, in a motor having a tachometer of an optical type. The phase detection apparatus eliminates direction sensitivity and does not suffer from the misposition of any upper and lower limits. The apparatus achieves a phase lock without excessive overshoot and eliminates the possibility of reverse run away under any condition. Moreover, the circuitry is easily implemented with a relatively few number of circuit components and therefore accomplishes the desirable functional capabilities at relatively low cost.

Abstract: The speed of a DC motor (10) is controlled by a servo which includes a digital phase lock loop. The motor drives a tachometer whose pulse (22) frequency is low relative to the frequency of a clock (21). The clock continuously drives a counter (200) whose ever increasing number content is gated to a data latch (26) upon the occurrence of each successive tachometer pulse, thus this data latch contains a first time-number of ever increasing magnitude. A second data latch (24) contains a second number. The difference in magnitude of two consecutive time-numbers is indicative of motor speed. Initially, this second number is set to contain a reference number (REF) which is equal in magnitude to the number of clock pulses which will occur between adjacent tachometer pulses when the motor is running at desired speed. A pair of limit numbers (RANGEL and RANGEH) are provided to define the upper and lower limits of servo saturation.

Abstract: A motor servo circuit is used in a recording and reproducing apparatus which comprises a loop including a comparator for comparing the phases of a signal which is responsive to the rotation of a motor and a reference signal and for controlling the rotation of the motor responsive to an output error signal.

Abstract: A system for detecting mechanical movement of a body under detection formed of: a synchro generator having a primary and a secondary windings, one of which is capable of being coupled to the body; an exciting circuit for providing exciting current to the primary winding; a reference signal generator for providing a reference signal of a predetermined frequency; a first circuit producing pulses at a frequency which changes depending on the phase difference between the reference signal and the signal induced in the secondary winding; and a frequency-divider counting the pulses and producing a first digital signal indicative of the count value at each moment. The first digital signal is supplied to the exciting circuit which determines the instantaneous value of the exciting current at each moment.

Abstract: A low cost servo operated digital positioning system which utilizes a phase shift control circuit in combination with an encoder and servo circuit for driving a moveable element. The encoder generates a pair of signals A which may be equivalent to a sine signal A and a cosine signal A. The phase shift circuit multiplies signals from the encoder by a sine of a demand signal B and by a cosine of the demand signal B and produces a sine (A+B) signal and a cosine (A+B) signal. These sine and cosine shift signals are introduced into a servo circuit for control of a moveable element. By phase shifting these signals it is possible to substantially increase the overall number of positions to which a moveable member may be moved and thereby substantially increase the overall accuracy of a positioning system.

Abstract: The motor control system for an electric motor having no mechanical means integral therewith for commutating current provides the ability to control position, velocity and torque of such a motor to the degree achievable with DC motors having mechanical commutators. Such a result is achieved by maintaining a desired spatial relationship between the resultant magnetic field created by the stationary member and the movable member of the electric motor. The control system includes detecting apparatus for detecting parameters of the motor that dictate, in part, the desired spatial relationship within the motor and command apparatus for creating a motor command signal which, when generated in the motor, causes the desired spatial relationship to be established. The present invention also permits maintenance of an optimal spatial relation--a spatial relationship that causes the motor to produce desired torque with a minimum excitation.

Abstract: A digital servo device having a servomotor with a feedback control device including a position detector. The detector detects the phase relationship among the various signals. The detector is a flip flop located between an AND gate and a differentiation circuit. The flip flop is connected to be set by a predetermined point detecting signal output from the AND gate and the flip flop is connected such that the positive and reverse direction command pulses are inhibited from being produced by locking a receiving shift register in response to an output signal from the flip flop. The feedback circuit is reset by a reset signal which comprises a differentiated output signal of the flip flop which has a pulse width wide enough for obtaining a resetting condition but not so wide that the next positive and reverse direction detecting pulses are extinguished.

Abstract: A speed control circuit for a DC motor has a phase comparator to which is supplied a theoretical frequency, emitted by a clock pulse generator, and an actual frequency, emitted from a pulse transmitter connected to the drive shaft of the motor. A first rotation direction signal, obtained from a rotation direction indicator, and a second rotation direction signal, obtained from the comparator, are combined in a logic element, the output of which is supplied to a drive circuit for driving the DC motor. A reference voltage is also supplied to the drive circuit, the reference voltage being obtained from another output of the comparator and supplied to the drive circuit through a filter. The reference voltage is a DC voltage which is proportional to the amount of phase deviation detected by the comparator. This reference voltage is utilized by the drive circuit to set the proportional value of the current supplied to the DC motor.

Abstract: An arrangement for determining the rotational position of the rotor of an electrical gyroscope is shown to include:(a) at least one sensor including a Hall effect crystal having a rotating magnetic field applied thereto, such field being synchronous with the field causing rotation of the rotor;(b) a phase-lock loop, responsive to square wave signals corresponding to signals out of the Hall effect crystal and a voltage-controlled oscillator to provide a signal approximating the rotational position of the rotor; and(c) a phase detector, responsive to negative going transitions of the square wave and to reference pulses to synchronize the rotational position of the rotor with the reference pulses.

Abstract: An improved microprocessor controlled scanning drum servo adapted for use in a recording and reproducing apparatus is disclosed. The scanner servo includes a velocity loop as well as a position loop, and by virtue of the fact that it is controlled by a microprocessor in a unique way, has extraordinary accuracy because the resolving power of the servo is essentially that of the microprocessor itself. The interrupts to the microprocessor occur in sequence with a first interrupt causing the microprocessor to cease current activity, store all required information in a stack register and thereafter wait until a subsequent interrupt occurs which enables it to immediately act to perform control operations with respect to the scanner servo. This enables the velocity loop to perform the vast majority of the work required by the servo and as a result of this, the phase closed servo loop operates as a positioning loop in the true sense.

Abstract: A brushless linear servomotor utilizes a first member provided with magnetic teeth having a large number of teeth-salients and slots arranged lengthwise of the first member at regular pitches and a second member which is moveable along the first member and has at least one magnetic core with magnetic teeth groups engraved thereon at surfaces opposite to the first member, and having a coil wound around each of the magnetic cores and further having a guide arranged to keep a constant gap between the first and second members. A number of non-contact detectors are connected to the second member so as to detect the salients and slots of the magnetic teeth of the first member. An electronic commutator and an electronic scale circuit are both connected to the non-contact detectors.

Abstract: A control for a robotic actuator employs a position processor to determine the phase of a pair of electrooptically generated position signals as well as to keep track of the number of whole cycles of the position signals. Whole cycles are tracked using a prediction technique depending upon the continuity of position and velocity. A command processor employing the sensed position produces a velocity signal for driving the robotic actuator. When very slow motion is sensed, the response of the controller is appropriately reduced to maintain a velocity command signal generally in proportion to the motion.

Abstract: An automatic control system for machine tools having rotary tools is disclosed in which the tool drive motor load current, which is proportional to the mechanical load on said drive motor, is maintained at a selectable desired level by controlling the duration and phase of the power supplied to an alternating current feed motor which controls the distance between the rotary tool and the workpiece. A sensed load signal which is greater than the preselected level will cause the feed motor to move the tool away from the workpiece, while a load signal less than that desired will cause the feed motor to move the tool toward the workpiece.

Abstract: Positioning of a movable body can be achieved at a high resolution by making use of two position signals generated by a position detector, whose magnitudes are sinusoidal functions having different phases of the position of the movable body. On the basis of the two sinusoidal position signals, two bi-level digital position signals having different phase from each other are derived, and digital control for movement of the movable body is effected by making use of these two bi-level digital position signals until the movable body is brought into the proximity of a desired position. Thereafter, control is switched from the digital control to analog control for movement of the movable body, in which a position signal whose manitude is a sinusoidal function of the position of the movable body and has a zero-cross point at the desired position is used as a reference position signal.

Abstract: A system for detecting mechanical movement of a body under detection comprises: a synchro generator having multiple-phase primary windings and a secondary winding, either of the primary windings or the secondary winding capable of being coupled to the body, and a phase-shifting circuit phase-shifting the secondary induced signal by 90.degree.. A phase comparator determines the phase difference between a set of two-phase reference sinusoidal signals and a second set of two-phase signals consisting of the induced signal and the phase-shifted signal. A frequency-divider counts pulses of a frequency proportional to the phase difference and produces a digital signal indicative of the count value at each moment. An exciting circuit for exciting the synchro generator determines the instantaneous values of the exciting voltage in accordance with the count value of the frequency divider.

Abstract: The number of data tracks or positions that a transducer can access or track is increased, beyond that conventionally permitted by the transducer conductor spacing, by first providing a plurality of signals corresponding in number to the factor by which the tracking capacity of the transducer is to be increased, with all signals having a common frequency equal to that of the drive signals applied to the transducer stator windings and with each signal being phase delayed relative to the other signals by one or more clock increments, then accessing the signal having a phase corresponding to the data track to be tracked, providing from that accessed signal a plurality of additional relatively phase delayed signals, and applying each of the later phase delayed signals to one of a plurality of phase detectors each of which also receives an input corresponding to the squared transducer rotor signal whereby the phase detectors provide at their output width modulated signals having a low frequency component correspon

Abstract: An electronic control system for a machine tool employs a monitoring system for monitoring the absolute position of a reversibly (and linearly or rotationally) movable moving member in the machine tool. The monitoring system includes a clock, a digital feedback position counter having a predetermined count range, an exciter, a feedback device responsive to movement of the movable member, a digital position storage device, a zero crossing detector, and a zero position counter. The feedback position counter, which operates at a clock frequency, controls the exciter which provides a pulsed exciter signal to the feedback device. The feedback position counter also provides a position count Nc to the position storage device and to the zero position counter.

Abstract: The resolver drive circuit on a numerical control system includes a microprocessor system which monitors the phase and amplitude of the sinusoidal wave forms applied to the resolver. Any changes in amplitude or phase shift of the applied wave forms due to such factors as time and temperature are automatically corrected by the microprocessor system. A highly accurate resolver position feedback system is thus formed with a minimal number of temperature sensitive components and a minimal number of required manual adjustments to analog circuitry.

Abstract: Apparatus for controlling the frequency of vibrations imparted by the vibrating element of a compacting machine to the ground which comprises a vibration pick-up responsive to the amplitude of vibrations of a mass composed of the vibrating element and the ground being vibrated which produces a vibration signal; a position sensor sensing the angular position of an eccentrically loaded rotary shaft on which the vibrating element is mounted, which produces a position signal; and a phasemeter which receives the vibration and position signals and provides an output signal related to the phase difference therebetween. This phase difference may be displayed in which case the motor for the rotary shaft can be controlled manually in accordance therewith or it may be fed to an automatic control system in which it is compared with a set signal to produce an error signal for automatically regulating the speed of motor turning the rotary shaft.

Abstract: A numerical control system is provided for a table having a relatively stationary member, a relatively movable member and a position transducer, such as an inductosyn, operatively positioned between them. The numerical control system comprises a high frequency clock which generates a pair of sinusoidal waves to the inductosyn at a lower frequency and the phase of the output signal from the inductosyn is representative of the position of the movable and stationary members. A direction and speed control circuit generates an output signal the frequency and polarity of which is indicative of the desired speed and direction of movement of the movable member, respectively, and this output signal is combined with the high frequency signal from the clock by a signal combiner.

Abstract: Variations of the speed of a video disc mastering turntable which lie within the lock range of a phase-lock-loop turntable speed control servo are detected by sensing variations of the loop phase detector waveform symmetry. Speed error limits are established by pulse forming circuitry which continuously restarts a timing circuit in one mode of operation and allows the timing circuit to complete a timing cycle in another mode of operation. A further timing circuit is arranged to reject multiple indications of the same speed error whereby a single output indication is provided for all speed errors occurring in a certain time period.

Abstract: A digital servo control system is responsive to a command signal indicative of a command position of a moveable element and to a phase modulated signal corresponding to the angle of rotation of a motor controlling said moveable element to develop a motor drive signal to position the motor. The system provides control during a velocity control mode and a position control mode, the latter occurring after the moveable element is moved to a predetermined small incremental distance from the commanded position. During the velocity control mode the motor is driven in accordance with a reference velocity selected in dependence upon the position error signal. Following a prescribed time after entry into the position control mode, the position error has added thereto an integration signal which increases in the same sense as the position error.

Abstract: A feedback control system is provided for control of a machine with a computer. A whole number command structure and a whole number feedback arrangement provide for interfacing a servo to a computer. Direct conversion between pulse width modulated and phase modulated signals and whole number digital signals facilitate computer interfacing to analog servos.

Abstract: A device for controlling the phase of an output pulse sequence relative to an input pulse train of the same frequency comprises a multiplier receiving the pulse train from a frequency generator and emitting to a divider a rectangular waveform having a frequency m times that of the pulse train. The divider is controlled by a comparator to divide the frequency of the rectangular waveform by a factor of m.div.1, m-1, or m, depending on whether the actual phase difference between the pulse train and the sequence is less than, greater than, or equal to a predetermined phase angle, the actual phase difference being communicated to the comparator by a counter registering during each cycle of the pulse train a number of pulses proportional to the phase difference.

Abstract: A device for position control including a first generator for delivering first and second identical signals dephased to each other by 90.degree.. A position pickup having two inputs connected to the first and second signals and an output for delivering a measurement signal whose phase is representative of the actual angular position of the component part to be controlled. A second generator for receiving a digital binary word instruction and for delivering an instructional signal of the same frequency as the first and second signals and having a phase representative of the desired angular position of the component part. A deviation signal generator connected to the output of the angular position pickup and the second generator for delivering a deviation signal representative of the dephasing between the measurement and instruction signals and a control device for controlling the angular position of the component as a function of the deviation signal.

Abstract: A control system for a veneer lathe feeds a knife into a rotating log to peel off a continuous sheet of veneer. When the knife is retracted, the orientation of the log is established and stored so that when the peeling operation is resumed, the knife motion is calculated to engage the log at the discontinuity in the log surface produced during retraction. In addition, when the knife engages the rotating log a compensation factor is momentarily added to the knife motion feed command to alleviate variations in veneer thickness caused by the mechanics of the lathe during impact. A considerable savings of veneer is obtained.

Abstract: A digital servo control system for controlling a drive motor accumulates speed and phase error numbers and produces a pulse width modulated signal in response thereto. Phase errors are measured by counting pulses of a clock signal between the arrival of a position signal related to a rotational position of the drive motor and the arrival of a reference signal. An automatic residual error compensating circuit controls a delay applied to the position signal in accordance with residual phase error to minimize the same.

Abstract: A positioning system is provided in which command and feedback signals are processed to develop an analog error signal for application to a servo drive to position a controlled element. The command signals are in the form of pulses each of which corresponds to a certain incremental distance of movement. The feedback signals are developed from phase shifts of a low frequency resolver signal, such phase shifts being proportional to movement of the element. Such feedback signals are applied to a resolver digitizer circuit which develops a train of resolver pulses in response to the phase shift represented by each feedback signal. Each such resolver pulse corresponds to the same incremental distance of movement as a command pulse and both the resolver pulses and the command pulses are applied to a comparator and error signal circuit in which any cumulative error in either direction is stored as a digital number and is converted to an analog error signal of the proper polarity.

Abstract: Digital servo apparatus includes a counter adapted to count inputted reference clock pulses to display time data. The output of the counter is latched by a first tacho pulse (controlled signal) to a first latch circuit and the contents of the first latch circuit is transferred by a second tacho pulse to the second latch circuit and the present count data of the counter is latched to the first latch circuit. A discrimination circuit is adapted to discriminate whether or not a control signal is within a predetermined control amount, based on time difference data latched to the first and second latch circuits, and deliver an output signal corresponding to a predetermined control amount based on the result of discrimination.

Abstract: In the disclosed system, if the frequency of input signals exceeds a value suitable for a load, the input signals and output signals are stored and compared in a comparator while locking of a phase locked loop is delayed by a loop filter that allows the output of the VCO (voltage controlled oscillator) to increase or decrease only at rates slower than given rates. When the input signals end after the loop locks, the filter delay causes the VCO to keep producing signals which are passed until the comparator recognizes that the number of output signals equals the number of input signals. If the input signals end before the loop locks, a logic circuit causes the VCO frequency to keep rising until another comparator indicates that the number of output signals has reached one-half the input signals.

Abstract: A feedback position control system and method of extracting feedback phase or position information therefrom. A resolver or similar device such as an inductosyn is connected to each movable member of a machine tool such that the phase of the resolver output signal is indicative of the displacement of each movable member about its respective axis. The stator windings of the resolver are excited with reference and quadrature signals to generate a periodically varying output signal. The zero crossings of the output signal are monitored and the digital count in a reference counter (C.sub.A and C.sub.B) corresponding to the times of zero crossing are stored. The scaled sum of the counts C.sub.A and C.sub.B is determinative of the phase of the output signal relative to the reference signal.

Abstract: A position pickup for numerically controlled machine tools having a resolver which is fed on the primary side by two voltages shifted 90.degree. relative to each other and which is coupled to the moving machine part. The voltages are generated in a digital sine-cosine generator made of decimal frequency divider stages. When the secondary voltage in the resolver goes through zero, as detected by a comparator coupled thereto through a filter, the state of the generator is transferred to a memory and serves as the actual position value. To compensate for phase drift in the filter used on the secondary side, the filter is connected at fixed intervals to a reference signal derived from the primary side and changes in the measured values so obtained, and stored in the memory, used for correcting the actual position value.

Abstract: A compensation circuit for overshoot, undershoot and delay occurring in response to sudden D. C. level changes in signals received by reactive filters. A D. C. level change, represented by an input signal step applied to the reactive filter is detected by the compensation circuit. The compensation circuit responsively provides a compensation D. C. signal step of a predetermined magnitude and polarity with respect to the input signal step. The compensation step is applied by the circuit to the signal return line of the reactive filter, simultaneously with the input signal step received by the filter to maintain a substantially constant D. C. signal level with respect to the reactive filter elements. The reactive filter elements are thus prevented from charging and discharging in response to the input signal step and filter delay is eliminated.

Abstract: In a control apparatus for a machine tool, a resolver interface circuit is utilized to determine whether or not the axis motors have driven the machine tool to the selected position. The resolver interface circuit synthesizes sine and cosine wave forms which are applied to a resolver which is mechanically coupled to the corresponding axis motor. The resolver interface circuit also synthesizes a signal which is phase related to the resolver excitation wave forms by the selected rotational displacement of the resolver and axis motor shafts required to achieve the selected position for the machine tool. The phase related signal and a positional feedback signal from the resolver are compared to generate an error signal to the driver for the axis motor. The selected position can be each incremental step where the axis motor is a stepping motor.

Abstract: An encoder interface circuit is responsive to command direction signals and pulsed command incremental rotation signals and to actual direction signals and pulsed actual incremental rotation signals to generate an error signal to a motor driver for controlling the movement of a servo motor. A position encoder is mechanically coupled to the servo motor for generating the actual direction and incremental rotation signals. The interface circuit generates a reference pulse train and an error pulse train, both at a relatively high frequency. The error pulse train is phase modulated by adding or subtracting the pulsed actual and command incremental signals according to the state of the corresponding direction signals. The reference and phase modulated error pulse trains are then compared to generate the error signal to the motor driver.

Abstract: In a digital servo control system (31) for a carriage of a serial printer or a like movable element, a control signal (125) digitally represents a reference angular velocity for a motor (26) until an instant at which a displacement from a current position of the element to a commanded position decreases to a predetermined value, a positional error during a preselected interval following the instant, and an integrated value (52) of a position error between the current and the commanded positions to suppress limit cycle after the interval. A PWM signal (56-57) is derived from the control signal and position pulses (62 or 63) representative of a variation in the current position. Preferably, small-amplitude limit cycle is forced to occur during the interval with the positional error indicated by a modified signal (182) derived by adding unity to positive and zero position errors.

Abstract: A digital servo circuit which, for example, may be used in a video tape recorder, for controlling the velocity and the phase of movement of a video tape by a capstan which is driven by an electric motor.

Abstract: In apparatus for measuring the relative position between a fixed member and a movable member, as in a flight simulator, means for electrically offsetting the position measurement to compensate for mechanical offsets and the like. The relative position may be extracted by applying reference oscillator signals to a stator winding, thereby inducing a signal in a rotor winding. The rotor signal is communicated to a digitally closed phase lock loop including a phase detector, an integrator, a loop filter, a voltage controlled oscillator, and a frequency divider having a counter. The invention provides value setting means such as thumbwheel switches, and comparison means coupled between the value setting means and the frequency divider counter, for generating a pulse signal when the counter contents corresponds to the value set in the value setting means.

Abstract: A digital servo system for a rotating member which detects a difference between phases of a reference signal and a signal representing the rotation phase of the rotating member thereby to control its rotation in accordance with the phase difference. Comparison is made by a digital rotation phase comparator between points of time at which first and second predetermined counts are made by a clock pulse counter which is cleared for each period of the reference signal and a point of time at which the rotation phase information signal of the rotating member is produced. When the rotation phase signal appears during an interval between the first and second counts, a latch signal is generated in synchronization with the rotation phase signal to cause an instantaneous count between the first and second counts of the counter to be loaded into a latch circuit.

Abstract: A professional audio tape transport capstan control system includes a single capstan continuously engaging a length of tape to provide bidirectional motion control in all modes of operation. A D.C. capstan drive motor is directly coupled to the capstan and energized for precise control over tape motion. A hybrid servo switches between digital position phase lock velocity control and analog constant acceleration control to provide both precise control over play speed and rapid acceleration. With acceleration to a stabilized play speed occurring in less than 0.5 sec an operator may treat the acceleration time as instantaneous for most applications.

Abstract: A high accuracy control system for driving a motor to move a member. The control system includes feedback means for generating a cyclical signal for providing an indication of the actual position of the member. The accuracy of the feedback means is maximized by introducing a gear mechanism between the motor output and the feedback means. Further provided are means for generating command pulses, each of which is indicative of an increment of commanded or desired movement of the member, and means for generating a command signal indicative of the desired commanded movement of the member. In one mode of operation, the incremental command pulses are multiplied by a factor of K to change the command signal by K increments for each incremental command pulse. In another mode of operation, M number of incremental command pulses are converted to a single incremental pulse, and this single incremental pulse is used to change the command signal by one increment of movement for M number of incremental command pulses.

Abstract: In a digital servo system suitable for controlling the rotational phase of a rotating body, such as, the rotary head drum of a video tape recorder (VTR), a binary output signal is provided, as a phase error signal, based upon the phase relation between a reference signal and a command signal showing the rotational phase of the rotary head drum, and such binary output signal is used to process a motor drive signal. Further, an analog servo system is used in association with the digital servo system to provide highly accurate correction of both high and low frequency phase errors.

Abstract: An apparatus forming an incremental motion system is described for controllably moving a load from a first position to a second position in a forward mode to track a moving object field in response to an external reference signal. The apparatus moves the load from the second position back to the first position in a reverse mode. A motor having a rotatable shaft supplies the moving force to the lens shuttle. An optical tachometer having a rotating apertured element fixedly secured to the shaft to rotate therewith generates a signal, upon serving each aperture, in each of the forward and return modes. The signals corresponding to served apertures define feedback signals having corresponding frequencies. A forward control circuit is responsive to the frequency of the reference signal and the frequency of the feedback signal in the forward mode to provide a forward control signal to an amplifier which energizes or drives the motor.

Abstract: A device which detects the amount of displacement of a movable member moved by a feed device, and which outputs pulse signals corresponding to the amount of such displacement.

Abstract: A higher order servo system including a phase transducer which produces two triangular waveforms, phase displaced 90.degree. in relation to each other, representing the positions of a movable member, and a commutating circuit, responsive to the triangular waveforms, for generating a sawtooth waveform and a velocity signal which is linear and continuous over the whole range of movement of the member. A counter and converter, responsive to pulses also generated by the commutating circuit, generates a staircase waveform, representing predetermined positions of the member, which is added to the sawtooth waveform to produce a positional error signal which is linear and continuous over the whole range of movement of the member. Optimal velocity and acceleration signals are derived from these two linear and continuous signals to drive the member to a desired position over the shortest path, in the minimal amount of time, and with no oscillatory motion at the desired position.

Abstract: A servo system, particularly well suited for use in a computerized numerical control system for a large machine tool, in which a plurality of axis controlling servo circuits are controlled by one computerized axis controller. As each controlled axis moves, an attached resolver's output is digitized to generate a digital position feedback signal which is compared to the desired position in the computer. The resultant error signal is converted to an analog voltage to control said axis motion. A digital clock and counter drives two digital to analog converters to create the two resolver inputs, and supplies timing signals to the computer, thus synchronizing the system.

Abstract: A phase-sensitive transducer apparatus comprises first and second relatively movable members, the first relatively movable member having a plurality of windings and the second relatively movable member having a winding. Means are included for applying a first input signal to one of the windings of the first relatively movable member and a second input signal to another of the windings of the first relatively movable member. An output signal is developed on the winding of the second relatively movable member. The first and second input signals are sinusoidal in nature of substantially identical frequency and peak amplitude and are phase-displaced by a predetermined amount, and the output signal is substantially constant in peak amplitude and variable in phase during relative movement of the first and second relatively movable members.

Abstract: A servo system has a moving member supported for movement therein and a pickoff device for sensing the position of the moving member relative to a reference position. The pickoff provides a position output which is connected to an attenuator at the input of a high gain amplifier having a feedback loop for attaining gain stability. The feedback loop contains circuit components which provide stability in the servo system. An amplifier output attenuator reduces the feedback loop signal levels. Amplifier output is coupled to motive means for driving the moving member toward the reference position. A timing circuit produces a timed output which dissipates over a predetermined period of time. The timed output operates to enable a field effect transistor which causes the input divider to attentuate the position output to the high gain amplifier.