Abstract: A brushless tachometer in which output signal switching is achieved using field effect transistors and which is capable of achieving linearity over a broad range, particularly the zero speed region. According to a preferred embodiment, the brushless tachometer is operated in a current mode as part of the servo loop to substantially reduce tachometer voltage switching requirements. A ROM can be used to control commutation switching. Commutation is preferable line-to-neutral to reduce ripple.

Abstract: A method and apparatus for controlling the position of a rotary member, particularly a rotary knife, utilizes a motor that is continuously coupled to the rotary member. A shaft position sensor and velocity sensor cooperate with motor control and drive circuitry to energize and brake the motor in accordance with the position and velocity of the motor drive shaft to provide a single cutting cycle each time a cut is required.

Abstract: A positioning apparatus for a magnetic disk drive apparatus including a biasing means for returning a carriage on which the magnetic head is mounted to a fixed position whenever a power source for the apparatus is cut off, and force compensation circuits operably connected to the carriage for supplying the carriage with an opposite force equivalent to the force of the biasing means as a function of the magnetic head position relative to the disk. The control force compensation circuits the speed of the carriage as it changes position from one track to another track and maintain the magnetic head in proper position over the selected track once it is reached.

Abstract: A control process and apparatus for positioning an electric motor provided with a rotation angle detector at a designated position positively at a high speed without being accompanied with hunting notwithstanding variation in the motor current and inertia of a load. The control process activated upon starting of the motor and ending at the stoppage of the motor at the designated position includes a first control region in which acceleration of the motor having been started is detected and subsequently a constant speed operation of the motor is effected at a maximum speed. A deceleration initiating time point is determined in dependence on the acceleration.

Abstract: In a dual mode servo for a rotary printer control system for controlling the velocity and position of a rotary print wheel and a print wheel carriage, the analog counterpart of a digital desired velocity multibit character is generated by a bidirectional digital to analog converter so that the analog desired velocity signal has a maximum value range lying both above and below a zero reference level, thereby eliminating the need for additional analog level converting circuitry.

Abstract: A motor speed control circuit produces indexing pulses during each revolution of the motor. Each indexing pulse triggers the production of a predetermined pattern of timing pulses. The timing pulses are integrated. The result of the integration is a relatively constant level signal that controls the motor current. At the end of a predetermined pattern of pulses in the binary signal, the integrator input signal goes to one of two binary states and causes the integrator output voltage to ramp up or down, as the case may be, until another indexing pulse is received from the motor. The output of the integrator upon receipt of the indexing pulse controls the speed of the motor while another set of binary pulses are being integrated.

Abstract: An improved technique for the counting of servo tracks in a position servo system wherein a single pulse is produced upon each crossing of a reference level by the servo data demodulation signal, the width of which is determined by the velocity of the servo data head relative to the medium.

Abstract: An improved control apparatus and method for servo system control is disclosed wherein a generally increasing or decreasing control signal is supplied to a source of energy when a desired parameter of interest produced by said source of energy is not equal to a desired value, and a constant control signal when the parameter of interest does equal the desired value. The constant control signal is determined by the previous constant control signal plus the product of the difference between the peak value of the generally increasing or decreasing control signal and the previous constant control signal multiplied by a constant.

Abstract: An improved magnetic tape drive having high performance specifications is achieved by microprocessor control of the capstan motion. Possible velocity profiles are stored in read-only memory and are selected on the basis of new input commands and last previous actions taken, whereby excitation of mechanical resonance inherent in the system is avoided.

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: A closed loop servo operated digital control system in which a dynamically operable moveable member can be effectively and accurately controlled during movement from an initial position to a command position by compensating for both velocity error and for position error. A differential between a present measured position of the moveable member and a command position provides a position error signal. Present velocity is determined by computing position differential as a function of time. A velocity error signal is obtained by subtracting the determined velocity from a velocity command which is stored as a velocity command profile. The total error is the resultant sum of the position error and a velocity error and this sum is converted to an analog signal in order to power an amplifier/motor which, in turn, provides power for the control system.

Abstract: An automatic velocity calibrator for a head positioning servo system in a magnetic disk drive performs a velocity calibration in a single pass over the magnetic disks by measuring actuator velocity and adjusting the gain of the velocity transducer in a series of successive approximations. Velocity is determined by turning a timer on in response to a track crossing and turning the timer off after at least two successive track crossings have been detected. A plurality of velocity measurements are stored and averaged. The average velocity is compared to a constant velocity command and an 8-bit latch is incremented or decremented in response to this comparison. A digital to analog converter produces a reference for an automatic gain control amplifier in the servo system which in turn adjusts the velocity transducer gain.

Abstract: A proportional plus integral servo-reversible speed control for use in a system driving a load in either a forward or reverse direction of travel at a desired output speed. The servo-reversible speed control includes a control handle for providing a command voltage having a magnitude proportional to the desired output speed for travel in the reverse direction and having a magnitude inversely proportional to the desired output speed for travel in the forward direction. A pulse pickup device and frequency to voltage converter provide a voltage proportional to the actual output speed, the actual speed voltage being applied to both an inverting and noninverting amplifier.

Abstract: A method and apparatus for controlling the angular position of a motor by controlling the revolution of the motor in response to a given positioning command value commanding a predetermined angular position of the motor shaft so as to stop the motor shaft at the predetermined angular position, wherein the acceleration of the motor being accelerated in the initial acceleration stage of the motor position control operation is calculated, and on the basis of the calculated acceleration and a commanded maximum velocity, the remainder angular distance between the deceleration starting angular position and the desired angular position of the motor and the deceleration command value in the deceleration stage are calculated so as to control the deceleration of the motor on the basis of the calculated values.

Abstract: A speed control system for a selection servomotor of an impact printer or the like employs a speed table which represents a series of speed data which are respectively matched with various differences between real and mark positions of a motor shaft. The speed table is stored to be selectively read out when addressed. A difference between real and mark positions of the motor shaft is added to a head address of the speed table, and the sum is used as an initial address for reading data out of the speed table. Thereafter, the speed data are sequentially read out up to the head address in accordance with the rotation of the motor shaft, so that the motor is driven in response to such various data. A plurality of such speed tables are prepared to vary the speed profile in matching relation with a specific initial value of the difference between the real and mark positions of the motor shaft.

Abstract: In a system for controlling within a very tight tolerance the speed of a DC motor, a first servo loop servos the motor to a speed which is close to ideal but not perfect. A second servo loop, operating in concert with the first servo loop, acts as a vernier or fine tuning adjustment to add any necessary correction needed to bring the motor into substantially perfect positional alignment.The first servo loop utilizes ramp and velocity feedback techniques to achieve constant acceleration by tracking or following a speed command signal profiled to have a linear velocity ramp portion and a final constant velocity portion where acceleration terminates and speed remains constant. Once the motor has accelerated up to the desired speed the second servo loop begins to function in concert with the first servo loop.

Abstract: A precision drive system including a base plate; track means and an air bearing means movable relative to one another, one of the means being fixed to the base plate and the other being movable for carrying an object to be moved relative to the base plate; means for moving one of the track and air bearing means; means for driving the moving means; and a control circuit including a power circuit for operating the means for driving; a velocity sensor for detecting the velocity of the movable one of the track and air bearing means, and a velocity feedback circuit for introducing velocity error signals into the power circuit to correct velocity; a position sensor to detect the position of the movable one of the track and air bearing means and a position feedback circuit for introducing position error signals into the power circuit to correct position.

Abstract: A method is provided for controlling the porosity of a web or film issuing from an electric spark perforating apparatus in accordance with an operator-set reference porosity regardless of variations in web speed, inherent web porosity, spark discharge energy and spark repetition frequency by controlling the frequencies of the electrical sparks applied to the web in accordance with the product of two signals, one a difference signal obtained by comparing the porosity of the web leaving the perforator and the reference porosity and the other signal derived from the speed of the web.

Abstract: A control device for multispeed motor having a first circuit for providing a detection signal whose period corresponds to a rotation speed of the motor, a trigger pulse generator connected to the first circuit for generating a trigger pulse corresponding to the detection signal, and a second circuit connected between the trigger pulse generator and the motor for providing a drive signal in accordance with the trigger pulse. The motor, first circuit, trigger pulse generator and second circuit form a closed negative feedback loop.

Abstract: A novel method and apparatus for dynamically monitoring the friction associated with an electromechanical system including a motor. The apparatus includes a closed loop servo with a unique filtering means in the feed forward loop for controlling the phase and magnitude of a "digital" ramp function used to drive the electromechanical system. The value of the filtered error signal outputted from the filtering means correlates with the friction in said electromechanical system.

Abstract: Servo Control System (24) for positioning a load (35). A velocity drive signal (50), derived from a positional error signal, is provided by the outer loop (28) as the input to a velocity servo inner loop (26). The velocity drive signal is non-linear (48) and of the form V=.sqroot.2AD where A is the acceleration of the load and D is positional error (46).

Abstract: A positioning control servo uses a digital feedback control system and an analog feedback control system, both simultaneously generating control signals to a servo summing node. The digital system derives negative feedback from velocity values which are raised to any programmed exponential value according to a linear velocity profile. The analog system feedback signals provide a non-linear velocity profile and fine position adjustment and dominates control at the servo end of travel. Interface control is provided from multiplexing a single digital feedback control system with a plurality of servo systems. The interface control selects a unique velocity profile in a digital system for each particular servo system. No switching is required between the digital and analog systems because both have continuous input to the servo summing node.

Abstract: A separately excited D.C. motor employs an analog servo control responsive to a speed control input signal that controls the derivation of a compensating signal for the motor back emf. The speed control and compensating signals are combined to control the motor speed via an analog regulator. A digital shaft encoder responsive to the motor position supplies a pulsed signal to a comparator that is also responsive to a desired position signal that is derived from the speed control signal. The comparator derives an integrated error signal that is supplied to the analog regulator. Application of the speed control signal to the regulator is delayed if a thermal simulator for the motor characteristics indicates motor overheating. In response to the compensated, desired speed indicating signal indicating that the motor has been ordered to stop, the error signal is decoupled from the analog regulator.

Abstract: An improved continuous-path-positioning servo-control system is provided for reducing the effects of friction arising at very low cutting speeds in the drive trains of numerically controlled cutting machines, and the like. The improvement comprises a feed forward network for altering the gain of the servo-control loop at low positioning velocities to prevent stick-slip movement of the cutting tool holder being positioned by the control system. The feed forward network shunts conventional lag-compensators in the control loop, or loops, so that the error signal used for positioning varies linearly when the value is small, but being limited for larger values. Thus, at higher positioning speeds there is little effect of the added component upon the control being achieved.

Abstract: A servo control system for the positioning of a projector comprising a dit current motor having the projector connected to the shaft of the motor, and a digital computer for providing command signals to move the projector to a programmed position at a programmed velocity within a predetermined time period. A potentiometer produced an electrical signal indicative of the actual position of the projector, and a tachometer produces an electrical signal indicative of the actual velocity of the projector. Feedback means, in turn, provides a position error signal indicative of the difference between the programmed position and the actual position of the projector, provides a velocity error signal indicative of the difference between the programmed velocity and the actual velocity of the projector, and varies, in response to the position and velocity error signals, the voltage level of the command signal such that the projector will attain the programmed position within the predetermined time period.

Abstract: A positioning control system which has a servo system provided with a position feedback system for detected positional information and a velocity feedback system for detected velocity information of a motor and in which the motor is driven by the servo system in accordance with commanded positional information to position a movable machine part of a numerical-controlled machine. The disparity between the detected velocity of the movable machine part and the detected motor velocity is fed back to the control input side of the motor, thereby suppressing vibration of the movable machine part at the moment of completion of the positioning operation.

Abstract: A tachometer for generating a velocity signal in a data disc pack servo system comprising a sampling pulse generator for producing pulses that are spaced from one another by a constant amount representative of a distance increment of radial movement of a servo head in the system, a timer for measuring the time between the sampling pulses, the timer including a clock pulse source and a counter which is started by one sampling pulse and reset by the next succeeding sampling pulse so that the digital output thereof is proportional to time and a computer for computing average velocity by deriving the quotient of the distance increment divided by the time required for the servo head to traverse such distance increment.

Abstract: A method of suppressing resonances in electro-mechanical servo systems is disclosed. The servo systems are of the type where first signals indicative of actual position of the servo system are differentiated and second signals indicative of the acceleration of the system are integrated. The differentiated signals are applied to the integrator in order to provide accurate initialization thereof. In modes of operation where the acceleration of the system is substantially zero, the differentiators are not used, thus decoupling the mechanical system from the electronic control system and eliminating resonance from the servo loop. The duty cycle of the differentiators is varied in differing modes of operation of the servo system so as to provide maximum bandwidth and speed to the system coupled with minimum errors in positioning. The system is described in connection with the servoing of magnetic read/write heads radially with respect to rotating magnetic disk data storage media.

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: Load actuating servomechanism apparatus includes dynamic regeneration to equalize and overcome a frequency-varying load/load drive train mechanical resonance. The drive circuitry comprises a per se conventional primary motor speed controlling rate feedback loop including a cascaded rate signal command source, summing error-signal producing node, and loop frequency response shaping filter and driver amplifier for exciting a load driving motor, and a rate tachometer signal feedback element connecting a measure of the motor output speed to a subtractive input of the summing node.To broaden the response band of the primary feedback circuit and accommodate a mechanical resonance otherwise interfering therewith, a secondary, positive feedback path supplements the input rate command with a signal dependent upon motor current, and thus upon motor load. Accordingly, output load drive automatically increases as motor current increases when a load drive retarding mechanical resonance is encountered.

Abstract: In a disc pack data storage system that has a plurality of discs and a plurality of heads for coaction with the discs, a tachometer for producing a signal indicative of the radial speed of the heads with respect to the discs. At least one of the disc surfaces is a servo surface and at least one of the heads is a servo head so that in response to radial movement of the servo head a triangular position signal is produced. Sampling pulses indicative of specific radial positions of the head are derived from the position signal so that the time required for the head to move between two positions represented by adjacent sampling pulses is inversely proportional to radial head speed. Control and computing circuitry measures the time between adjacent pulses by providing a clock pulse source and counting the number of clock pulses that occur between adjacent sampling pulses.

Abstract: Load actuating servomechanism apparatus includes dynamic regeneration and a mechanically damped motor-load coupling to equalize and overcome a frequency-varying load/load drive train mechanical resonance. The drive circuitry comprises a per se conventional primary motor speed controlling rate feedback loop including a cascaded rate signal command source, summing error-signal producing node, and loop frequency response shaping filter and driver amplifier for exciting a load driving motor, and a rate tachometer signal feedback element connecting a measure of the motor output speed to a subtractive input of the summing node.To broaden the response band of the primary feedback circuit and accommodate a mechanical resonance otherwise interfering therewith, a secondary, positive feedback path supplements the input rate command with a signal dependent upon motor current, and thus upon motor load.

Abstract: In a positioning control system of the type which controls an object to be controlled to a target position by the use of a servo system, the present invention is characterized in that when a position deviation between the present position of the object to be controlled and the desired target position is smaller than a predetermined value, the servo system is actuated for a first period of time in accordance with the position deviation by means of a control signal which is greater than that normally warranted by the position feedback gain which is provided in the servo system, and is thereafter changed over to a servo system which is actuated by the position feedback gain either after a predetermined time or when a predetermined velocity has been achieved.

Abstract: An electronic tachometer that includes an integrator for producing a speed signal by integrating a signal representative of acceleration of a body and a differentiator for producing a speed signal by differentiating a signal representative of the position of the body, the differentiator being formed by a passive RC circuit and operatively associated with circuitry for alternately supplying to the differentiator two signals representative of position, one of which is inverted so that signals of a single polarity are supplied to the differentiator, and further circuitry for connecting the differentiator output to the integrator feedback circuitry so as periodically to update or reset the speed signal produced by the integrator, which is formed by an operational amplifier having a capacitive feedback which is shunted by a resistor when the differentiator output is active to update the integrator.

Abstract: A servomechanism comprising an operational amplifier; a servomotor driven by the amplifier, the amplifier having limited output voltage and current capabilities, i.e. being non-linear; a position sensor; and a position error detector. A negative feedback circuit integrates the limited amplifier output and mixes it with the error signal so as to produce, in the output of the amplifier, a signal proportional in voltage-time product to a derivative of error, even when the output amplitude is limited. Therefore the servo is positioned in the minimum possible time commensurate with the limited capability of the amplifier, without overshoot or undershoot.During an extended slew, the error signal output of the position error detector also becomes limited. Hence, shorting means are provided to prevent undue build-up of the integrated amplifier output feedback signal during this time, and to short a DC feedback blocking capacitor.

Abstract: A rate-control servomechanism includes a load driving motor and a tachometer mounted on the motor shaft to produce a feedback signal hich corresponds to the rotational speed of the motor. An additional signal corresponding to the motor current is added to the tachometer feedback signal to compensate for the resonance-like effects resulting from the inductive coupling between the motor and tachometer windings.

Abstract: An electronic tachometer comprising an integrator having its output coupled to a variable gain amplifier and responsive to an input signal representative of the acceleration of a moveable load, such as a head assembly of a disk drive, for producing a coarse velocity signal at the output of the variable gain amplifier indicative of the load velocity, a tachometer gain correction circuit including another integrator coupled to receive the coarse velocity signal to produce a coarse distance signal indicative of distance traveled by the load and means for combining the coarse distance signal with a reference distance signal to produce a distance error signal which functions to adjust the gain of the variable gain amplifier so as to vary the coarse velocity signal to make the coarse distance signal equal to the reference distance signal, and accumulative error compensation means coupled to receive a gain indicative signal derived from the distance error signal to produce a signal input to the tachometer integrator

Abstract: In a speed feedback control system wherein a speed command signal and a speed feedback signal are compared and wherein the deviation between these signals is entered into a speed control unit, the speed signal is differentiated to apply speed damping in order to suppress the oscillations of the control system. In this case, while the speed command and the actual speed make a great difference transiently, the speed command is approximate to the sum between the speed feedback signal and the damping signal even transiently. Therefore, the speed command signal is compared with the sum between the speed feedback signal and the damping signal, and the fault of the speed control system is detected upon the fact that the deviation has exceeded a predetermined value.

Abstract: A device is disclosed for damping the critical frequencies of a rotor suspended by a radial electromagnetic bearing which has means associated therewith for detecting the radial position of the rotor, comprising a servo-circuit for connection between the detecting means and windings of the electromagnetic bearing and including a circuit for controlling the current supply to the windings in response to signals from the detecting means to keep the rotor in a predetermined radial position. The servo-circuit is provided with means for the selective amplification of the phase advance gain of said circuit in a frequency equal to the speed of rotation of the rotor for damping said critical frequencies.

Abstract: An adaptive interface circuit for use in coupling movement commands to a device utilizing linear actuators to control the rotational position of a rotatable member. Since the rotational position of the rotational member is not a linear function of the extension of the linear member, the rotational controller may be characterized as having a gear ratio which varies with the position of the rotatable member. The system includes an adaptive interface which modifies the gain of the movement commands in a manner designed to offset gear ratio changes so that the system as a whole will respond linearly to the movement commands. The system is described with particular reference to an antenna tracking system.

Abstract: A radio controlled guidance and speed control system for a vehicle has spaced receivers for receiving magnetic energy signals from a movable energy source. The signals received vary in accordance with the position of the receivers with respect to the energy source, and are electrically processed to control separate motors driving two wheels of the vehicle for starting, stopping and direction controlling. The circuit for processing the received signals comprises a summing amplifier for speed control, two differential amplifiers for direction control and a gate connected to the summing amplifier through a comparator to provide a stop signal. The circuit provides for a gradual acceleration of the motors. One of the receivers is connected to the gate for developing a stop signal to prevent utilization of ambiguous signals from the other signal receivers.

Abstract: An automatic guidance device for a self-powered cargo-moving vehicle is bolted directly over the steering column of the vehicle and is operated by a vehicle-borne sensor which follows a magnetic wire path, the guidance system having an automatic, sensor-directed mode, a manually operated power steering mode, and a manual override mode in which the guidance device is effectively disconnected and steering is undertaken by a direct mechanical linkage with the vehicle steering column.

Abstract: This invention relates to an improvement in a device for adjusting an original to be copied, in particular an original which is repeatedly conveyed through the exposure station of a photocopying machine, including a transport mechanism with a deviatable transport band arrangement adapted to transport said original at a variable speed, and when said original is to be copied a number of times, in a closed path, further including a device for lengthening the path on one side, two switches positioned transversely and normal to the direction of flow and adapted to be actuated by the original whereby a switching circuit to a servomotor is closed when the leading edge of the original deviates from a correct position, said servomotor being connected to a correcting element adapted to change the length of the path of the original on one side of said transport band arrangement, the improvement comprising generator means adapted to put out a first signal proportional to the transport speed of said original, said servomo

Abstract: A camera-position control is disclosed which includes a multi-axial, manual control of a generator for an electronic pointer for generating a spot at the focus of interest of a scene and for directing the spot to accompany a moving subject or to migrate to a second focus of interest, the signal generated for moving said spot being coupled to a multi-axial, camera-positioning drive circuit which includes tachometer generators whose output is imposed on the generated positioning signal for their respective axes to oppose that signal and thereby impose a rate control on the camera-positioning drive.

Abstract: A control system for precisely locating a tape upon deceleration thereof from a transport velocity to rest. A signal is generated which represents the distance traversed by the tape subsequent to an identified event. The signal is compared with a reference signal representing a desired distance-versus-time characteristic, and the error signal thus given rise to is used to either "plug" or dynamic brake the motor to control the stopping distance. Final position control logic produces and additional enabling signal should the tape overrun its desired position, and causes the motor to reverse to reposition the tape. In a preferred embodiment, a current limit circuit monitors current through the drive motor, and intermittently disables a portion of the drive circuit in response to a sensed overcurrent condition.

Abstract: A high-speed printer with a printing wheel with the individual type elements supported by radially extending spokes. Separate servo systems provide intermittent movement for the printing wheel and the carriage carrying the printing wheel.

Abstract: Numerical control means for controlling the position of a machine tool or the like by means of a servomotor are described. A position command signal is compared to the signal indicative of the servomotor position, and the resultant error signal is added to a speed command signal to control the speed of operation of the motor. A follow-up signal is generated whenever the amplitude of the error signal exceeds a predetermined level, and the latter is added to a digital position signal coupled to the system. A constant digital signal generated by said follow up signal is added to said error signal instead of said speed signal.

Abstract: The disclosure relates to a non-minimum phase linear controller which uses positive servomechanism rate feedback to control hydraulic mechanisms. The disclosure also relates to a controller comprising, in combination, a conventional linear controller and a non-minimum phase linear controller, the outputs of the combined controllers being weighted in a predetermined ratio to provide a single output control signal.