Abstract: A dual mode, digital servo positioning system controls servo motor current by a processor-generated current control set point in conjunction with velocity feedback. When the motor has advanced to the vicinity of a target position, the processor opens the velocity feedback loop and reduces servo amplifier gain, such that the set point controls motor current without velocity feedback. This open loop condition provides a springy servo response that eliminates oscillation due to small deviations from target position caused by electronic drift or gravity. Position information is provided to the processor by means of quadrature encoded tachometer pulses from the motor.

Abstract: An adaptive motor pulsing apparatus for a driven element positioning system is disclosed which divides the available time between recurring motor on periods and motor off periods, and which also varies the duty cycle of the motor during successive on periods in order to provide precise positioning control. The final approach uses a "nudging" technique which increases the duty cycle by increments until forward motion of the driven element is detected.

Abstract: The device can control an electric motor intended to rotate the drive shaft of a movable member, solar protection member, closure member or the like.The control device comprises a pulse generator device and an angular position coder, governed as regards rotation by the drive shaft, provided for supplying a signal permanently to a logic processing unit connected, through the intermediary of an input-output interface, to the terminals of the pulse generator device and of the coder and, through the intermediary of an output interface, to the electric motor. The means for regulating the stopping positions are constituted by switches connected, through the intermediary of an input interface, to the logic processing unit, in order to memorize the desired angular stopping positions in the working memory of the latter. A non-volatile memory is connected to the logic processing unit for safeguarding these angular positions in the case of a cut in the power supply.

Abstract: A closed-loop feedback-controlled servo system is disclosed which reduces command-to-response error to the system's position feedback resolution least increment, .DELTA.S.sub.R, on a continuous real-time basis for all operating speeds. The servo system employs a second position feedback control loop on a by exception basis, when the command-to-response error .gtoreq..DELTA.S.sub.R, to produce precise position correction signals. When the command-to-response error is less than .DELTA.S.sub.R, control automatically reverts to conventional control means as the second position feedback control loop is disconnected, becoming transparent to conventional servo control means. By operating the second unique position feedback control loop used herein at the appropriate clocking rate, command-to-response error may be reduced to the position feedback resolution least increment. The present system may be utilized in combination with a tachometer loop for increased stability.

Abstract: In a rotary printer control system, a dual mode servo for controlling the velocity and position of a rotary print wheel and a print wheel carriage is normally operated at a relatively high gain value. When the servo is switched from the velocity mode to the position mode, the length of time the servo remains in the position mode is monitored and, if this exceeds a predetermined maximum time period, the gain of the servo loop is switched to a relatively low value in order to reduce oscillations of the print wheel or carriage about the HOME position. The gain reduction is accomplished by inserting a supplemental R-C network in parallel with the high gain R-C network, and the range or ratios of the relatively high gain to the relatively low gain values is from about 10 to about 30.

Abstract: An induction motor is coupled to a movable load to be positioned. The induction motor has two or more stator windings. Alternating current power is connected to the stator windings to energize the motor. A transducer senses the position of the load. Responsive to the transducer, the alternating current power is disconnected from the stator windings as the motor approaches a predetermined load position. Also responsive to the transducer, a direct current energy storage device is connected to the motor as the motor approaches more closely to the predetermined load position to apply direct current to the stator windings and to stop the motor at the predetermined load position. Preferably, the storage device comprises a capacitor connected in series with a rectifier across two input terminals of the motor and the storage device is connected to the motor by a relay coupled from the junction of the rectifier and capacitor to one of the input terminals of the motor.

Abstract: To enable a microprocessor to operate within its bandwidth limitations while controlling a serial printer, means are provided for adjusting the microprocessor system clock rate when the printer is in its rate mode. In particular, the output of a counter clocked by the pulses from an encoder representing the velocity of a member is controlled; the output of the counter being selectively applied to the microprocessor in accordance with the velocity of the member being controlled.

Abstract: Stage 12 is moved into position by traction of capstan 38 on bar 42 which is pivoted under intermediate plate 20, and by traction on bar 66 which is pivoted under stage plate 12. Bar 42 is pressed against motor driven capstan 38 by pressure rollers 44 and 46. The pressure rollers are mounted on a rotatable yoke 50 so that the bar can freely swing and only applies longitudinal forces to the plate. This same structure is provided for drive bar 66.

Abstract: A method and apparatus for controlling the return of a movable element of a machine tool to a predetermined grid point by controlling a movable element drive device in accordance with feedback pulses generated while the drive device is being driven to transport the movable element between grid points. The method includes the steps of specifying a position remote from the predetermined grid point by a distance which is less than the spacing between grid points, computing the deviation between the specified position and the current position of the movable element, positioning the movable element at the specified position by driving the drive device on the basis of the computed deviation and the feedback pulses, and driving the drive device at reduced speed to stop the movable element at the first grid point encountered following the initiation of reduced-speed drive.

Abstract: A method for controlling the locus of an arm of an arm type robot or the like, wherein a control system which drives a first arm of a two-joint arm under open-loop control and a second arm under feedback control is provided. A bang-bang drive system is used for positioning the first arm in a minimum time. The position of the tip of the second arm can be detected either from the rotational angle of each arm or by means of a position recognizing device. Furthermore, an arm positioning method for rapidly bringing the tip of a multi-joint arm to a desired position while detecting the positions of its tip and its joints by simple calculations is disclosed.

Abstract: A linear servo system including a linear motor with a moving permanent magnet the flux of which interacts with current flow through a stator winding. A position servo loop controls the position of the permanent magnet and preferably includes a position transducer located within the motor air gap. The servo system when used in combination with a disk drive preferably includes a coarse/fine positioning program to first move to the desired disk track area and to then move to the center of the disk track. The motor winding located in the air gap can be made of iron or copper clad iron to reduce the size of the effective air gap.

Abstract: An electrically controlled (16) mechanical actuator (13) is driven by optically generated (23) electrical power through an optically controlled (28) switch (26) in an electrically isolated module (20). Optical transducers (54, 62, 70) and feedback (29), as well as optical inputs (40, 89, etc.) to electrical signal processing equipment (46, 47, 49) in an electrically isolated module (22) dictate the electrical control (28). A helicopter flight control system is wholly digital, with solar remote power and optical intercommunication.

Abstract: A digital positioning system having high accuracy is disclosed, which employs an incremental position optical encoder as the position transducer. In response to the output signal from the encoder, the system provides coarse and fine position signals which are combined to form a composite digital signal representing the absolute position of a moveable control member. The composite position signal has a resolution of greater than one part in one million. Trigonometric conversion techniques are used to derive high resolution incremental position information from the encoder output signals.

Abstract: An automatic storage and retrieval system including a storage bin, having a mechanism for positioning a vehicle at the storage bin including a rough positioning mechanism with an encoder having a rotatable member which rotates through an arc less than a complete revolution in response to movement of the vehicle and generates a signal with a different value at each of various member positions which correspond to respective vehicle rough position zones. A control device receives the signal and selectively causes the vehicle to move to a rough position zone at the storage bin. A fine positioning mechanism repositions the vehicle within a particular position zone after rough positioning and utilizes a light source and photoelectric sensor mounted on the vehicle for detecting a target mounted in a fixed relation with respect to the storage bin. The control mechanism receives an electrical signal generated by the photoelectric sensor and causes the vehicle to stop at the fine position location at the storage bin.

Abstract: A vertical-type machining center having a spindle carrier which travels in the vertical direction and a turret capable of both rotation and upward and downward movement provided on the spindle carrier, wherein tools are automatically changed over through rotation of the turret caused by relative movement between the turret and the spindle carrier when the upward movement of the turret is checked by a restraining member. A Z-axis position pulse generator is provided on a spindle mechanism drive member, such as the vertical drive motor or a screw shaft, and is adapted to generate a pulse for each revolution of the drive member. The pulses are counted by a counter which delivers a counted value for use in computing the vertical position of the spindle mechanism. The arrangement is such that the rotational speed of the vertical drive motor is controlled so as to move the spindle mechanism at an optimum speed suitable for the vertical position thereof.

Abstract: Settling problems of a closed loop servo system are substantially eliminated by switching the servo system into position mode operation only when there is zero position error and zero velocity error. The fast and clean settling is accomplished by digitizing the instantaneous amplitude of the position signal when the difference count has decremented to zero and using that digital value as the address of a square root look up table which provides for each instantaneous amplitude of the position signal a digital signal indicative of the instantaneous velocity required to effect rapid settling at the rest position. The digitized velocity signal is converted to an analog signal by a digital to analog converter for energization of the drive motor.

Abstract: A motor control positioning apparatus and method are disclosed wherein variable duration pulses are fed to a DC motor. After the vicinity of the destination has been reached, the final pulsing stage is initiated, in which a short duration pulse is fed to the motor; position is then checked to determine if forward movement of the driven element has occured; and if movement has not occurred, the pulse duration is increased by an increment which is repeated until movement does occur. Thereupon a new series of such pulses is started; and this cycling continues until destination is reached.

Abstract: A signal generating means including a half-round magnet attached to the spindle of a machine tool and mounted relative to a first reference indicator and a pair of opposingly mounted magnetic switches magnetically coupled to the magnet and mounted to a stationary portion of the machine tool and aligned relative to a second reference indicator for generating a first signal when the first magnetic switch is activated by the magnet, a second signal when the second magnetic switch is activated by the magnet; gating means, responsive to the first and second signals for generating an orient signal to orient the spindle to a reference position and a controller means for supplying to the spindle driving signals during the normal mode of operation and for supplying to the spindle during the orientation mode orient signals to cause the spindle to become aligned to the reference position.

Abstract: Apparatus is disclosed for controlling the movement of a movable element to bring the movable element to rest at a desired stopping position. The apparatus comprises a multi-phase drive motor having a drive shaft coupled to the movable element for driving same, four electrically conductive coils mounted in position-displaced relationship about the shaft, and means coupled to the drive shaft and responsive to the selective energization of the coils by respective motor drive signals for causing the corresponding rotation of said drive shaft and movement of said movable element. A sensor is coupled to the drive shaft and is responsive to the rotation thereof for generating an electrical signal containing information indicative of the direction, speed and distance of movement of said movable element. Further, means are included for detecting from the distance information indicated by the electrical signal whether the movable element is within a predetermined distance of said desired stopping position.

Abstract: A spindle orientation control apparatus having a motor for driving a spindle, speed control means for rotating the spindle at a speed in accordance with a command speed, and position control means for stopping the spindle at a commanded stopping position. The apparatus is further provided with stopping position command means for digitally instructing the spindle stopping position, a position sensor, error monitoring means for monitoring an error between the commanded stopping position and the actual rotational position of the spindle and for generating a signal when the error attains a predetermined value, and means for generating a signal indicative of an orientation speed. When the apparatus is in a spindle orientation control mode, the spindle is speed-controlled so as to rotate at the orientation speed until the error monitoring means generates said signal, and is position-controlled after the generation of the signal so as to reduce the error to zero.

Abstract: A digital servo system adapted for use in a dual mode coarse-fine servo system to control a movable member from a starting position to an at rest destination position. The digital servo generates a pulse train in response to varying space phase cyclic analog position signal A from an encoder coupled to the movable member. Each cycle of an analog position signal represents a small incremental amount of movement by the movable member. The pulse train provides a change in its state in time with the varying position signals. In the preferred embodiment, eight changes occur per cycle. The pulse train is integrated to provide a velocity signal which is compared with a command velocity signal.

Abstract: A digital motor control positioning system, and method, are disclosed in which lead screw position is measured by an encoder, and the error between that position and the destination is measured, either continuously or repetitively, to provide digital, distance-representing control pulses to the motor. In the final, settling-in portion of motor movement, it is successively started and stopped to provide incremental distance movements, which preferably are reduced in size as the destination is approached.

Abstract: A position control system is disclosed for aiming a mobile rocket launcher having positionable axes in the azimuth and elevation planes. The control system has a separate control subsystem for each axis of movement, and each such subsystem includes an initial aiming signal processor providing a course positioning function and a reaiming signal processor providing a fine positioning function. The initial aiming processor receives signals representing a desired position (DP), a feedback signal representing the actual position (AP) updated at predetermined sampling intervals, and an error signal (E) representing the difference between DP and AP. From signals representing AP and E, and a constant representing the stopping time of the launcher mechanism for a given control axis, the initial aiming processor produces a predicted position signal (PP) which represents the position that the launcher will reach upon termination of the actuator drive for that axis.

Abstract: A spindle control system which is provided with a first motor for rotating a spindle, a second motor for positioning the spindle, a pulse generator for generating pulses proportional in number to the rotational angle of the spindle, a counter for counting the pulses from the pulse generator in order to detect the rotational position of the spindle, and circuitry response to the counter means to control positioning of the spindle by the second motor.

Abstract: A microprocessor controlled printer includes a forms feed assembly, a dot matrix print assembly, a ribbon drive assembly and a number of emitter assemblies associated with the foregoing to provide positional information during operation of the printer which prints on a line-by-line basis. During the printing of characters, such as Kanji characters, extremely accurate control of dot placement is required. In order to achieve a balance between the operating cycle times of the microprocessor and the forms feed assembly, the microprocessor analyzes emitter pulses in two stages. One stage involves use of relatively low frequency emitter pulses for start-up, normal speed, and high speed operations. Another stage involves use of an additional emitter track that produces high frequency pulses utilized by the microprocessor during stopping conditions to achieve greater precision in final positioning of the forms.

Abstract: A theoretically optimum motor drive time period or drive pulse width is computed as a function of the number of steps from the present motor shaft position to the desired command position and the present motor shaft rotational speed. A compensation factor is computed as a function of the present motor shaft speed and the torque-speed characteristic of the motor (12) and multiplied by the computed drive time period to produce a present drive time period for energization of the motor (12) for rotation of the motor shaft (14) from the present position to the next step position. After the motor shaft (14) has been rotated to within one step of the command position, sensor means (18') sense displacement of the motor shaft (14) in excess of a predetermined small angular distance from the command position and cause the motor (12) to be energized to rotate the motor shaft (14) toward the command position.

Abstract: When the carriage of a machine is positioned at the reference position of the machine through coarse positioning and fine positioning, coarse positioning is first carried out so that the carriage can move in either direction according to the initial position of the carriage. The movement of the carriage is sensed by the combination of a platform mounted on the bed of the machine and a micro switch mounted on the carriage. The carriage is first moved at high speed and, when the carriage passes the reference point, it is moved at slow speed to return to the reference point. When the carriage again passes the reference position, coarse positioning finishes and fine positioning begins. In order to ensure coarse positioning in either direction and the change of direction of the carriage, a direction circuit is provided in a control unit of a numerical control system.

Abstract: An adaptive position control system including X, Y and .theta. stages and their associated positioning and motion detection apparatus, position detection apparatus for detecting the position of the stages relative to a fixed reference, X and Y position control subsystems responsive to signals developed by the motion and position detection apparatus and operative to generate coarse mode and precision mode drive signals for application to the X and Y stage positioning apparatus, X and Y adjust subsystems for enabling adjustment of the position detection apparatus, and a .theta. adjust subsystem operative in a coarse mode and precision mode for adjusting of the angular orientation of the .theta. stage. Operator control input to the various subsystems is accomplished by means of a joystick control mechanism and central processing unit.

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: A dual mode servo-system providing improved motion characteristics and improved noise immunity. A relatively movable member is driven by control signals derived from actual velocity feedback signals during coarse mode operation. At the beginning of fine mode operation the actual velocity signal is sampled and used to generate a synthetic velocity signal used to control motion of the member during final deceleration, along with an actual position feedback signal, the synthetic velocity signal having a decreasing magnitude tailored to a particular application. At a predetermined maximum time period, after detent of the member, a time out circuit re-inserts the actual velocity feedback signal.Control signals for the driven member are also derived from the actual motor current by integrating the motor current, the integrated current signals being used to control motion of the member during coarse mode operation only.

Abstract: A positioning system for moving a member between positions in time optimal fashion employs concurrent "feedforward" and "feedback" control. The feedforward control system provides major control and the feedback control system provides minor control to correct for deviations between the actual and a nominal system. The feedback loop may thus be of low bandwidth permitting desensitization to high frequency disturbances or the employment of inherently low bandwidth controlled variables.The "feedforward" control function includes successive portions of opposite polarity corresponding to acceleration and deceleration of the member and also includes a subtractive velocity related component. This function represents the approximate current input to an electromagnetic coil actuator of a nominal system required to move such a member between positions in time optimal fashion.

Abstract: The actual drive signals to a stepper motor which rotates a mechanical device provide low order bits used in place of the low order bits of a digital word derived from an analog position sensor, to provide an accurate feedback word for subtraction from a digital position command word so as to generate a position error signal to drive the stepper motor in a servo loop.

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: A read/write head moves relative to magnetic discs having track addresses corded thereon in Gray code in a plurality of reference zones. The head is moved by an electric motor and reads information as the head is shifted from a starting track to a destination track. The address of the destination track is expressed in weighted, i.e., standard, binary code, and is stored in a register. The address of the head is read by a read element of the head from the recording tracks. In response to the initial and destination tracks, an intermediate track C, approximately halfway between the initial and destination tracks, is calculated. The head is accelerated from the initial track to the intermediate track by feeding a motor for driving the head with a constant current. In response to the head detecting the address of the intermediate track, the current supplied to the motor is reversed so that the head is decelerated. The calculations and comparisons are performed in the weighted, binary code.

Abstract: In a disc drive which does not have a head position sensor but does have a velocity detector and off-track error detection means for sensing the distance and direction of the displacement of the head from the nearest track center, and in which the direction signal from the error detector is of one polarity for odd numbered tracks and of the opposite polarity for even numbered tracks, a system is provided for capturing a track on a blind seek which involves detecting deceleration of the head to below capture velocity, allowing the head to drift past the next track center while sensing whether that track is odd or even, and then initiating a capture of the next following track on the basis of whether the detected track is odd or even and the direction of seek.

Abstract: In infrared spectroscopy utilizing an interferometer, position stepping of the optical path difference in the interferometer must be accomplished quite rapidly in response to a drive signal applied to a moveable mirror in the interferometer which is proportional to the offset distance desired from the previous null point. As the mirror moves in response to this drive signal, effectively getting closer to the new null point, the drive signal is gradually reduced, in response to detected reference laser fringes. At the new null position, the drive signal will effectively be zero. A binary up/down counter drives a digital/analog converter (DAC). The output from the DAC is supplied to the mirror moving means. The fringes generated by a reference laser are detected as the mirror moves, causing the up/down counter to be decremented to its null count, thereby reducing the output of the DAC, as the mirror moves towards its new null position.

Abstract: An absolute positioning servo for positioning a shaft in response to a digital command input which utilizes a resolver, for providing an analog position indication of the shaft, an analog to digital converter, which provides a digital indication of the shaft position, a comparator for comparing the digital command input signal with the digital indication signal and providing a differential digital error signal which is converted to an analog signal and fed back to position the shaft so that the differential digital error is 0. An analog fine control positioning means is provided which positions and maintains the shaft near the center point of the position represented by the digital command input signal when the digital differential error is 0. A signal representing the difference between the exact analog position of the shaft and the digital approximate position of the shaft is provided at the output of the translator.

Abstract: A closed loop servo system for positioning a head relative to a magnetic recording element wherein track crossings are normally utilized to generate a feedback signal to the servo for positioning the head and wherein for a precise indication of head positioning between track crossings the velocity of movement of the head is integrated and fed into the servo system to provide a fine position signal.

Abstract: A material transfer apparatus which includes a carriage whose movement is controlled along a path between specified locations thereon. The carriage includes means for dynamically indicating its present location on the path which is compared with a specified new location to provide a difference drive for moving the carriage as required.

Abstract: A device for precisely positioning a movable member along a rectilinear path, wherein a plane conductive winding is attached to and moves with said member, wherein sensors are spaced apart along said path opposite to said winding, and wherein a control circuit responds to the signals generated by said sensors for servoing the motor that drives said movable member.

Abstract: An apparatus for positioning a carrier means along a line of print in either of two directions. The carrier means is positioned by a D.C. motor which is driven by a pair of current driver circuits, one of which controls the flow of drive current in a forward direction and the other of which controls the flow of current in the reverse direction. The motor is capable of driving the carrier means at a first predetermined high speed when it is determined that the desired destination carrier position is more than a predetermined number of carrier positions from the present carrier position and at a second predetermined low speed when the desired destination carrier position is less than or equal to a predetermined number of carrier positions from the present carrier position. An electronic tachometer means operates to maintain a relatively constant speed while operating in the predetermined high speed state and while operating in the predetermined low speed state.

Abstract: A device for the precise positioning of a movable member includes means for generating signals permitting localization of successive stop positions of the moving member and means for generating a pulse whenever the member approaches any stop position within a distance that equals a given fraction of the distance between two successive positions; when the member approaches a prescribed stop position, the relevant pulse ensures the enablement of a circuit that controls the precise stopping of the member. The device is particularly useful for setting a magnetic head on a given track of a magnetic disc.

Abstract: A solid-state resolver apparatus comprising cascaded coarse and fine-angle resolvers. The fine-angle resolver includes first and second averaging means for averaging input and output signals, first and second multipliers for multiplying a digital angular input signal by the outputs of the averaging means and first and second summing means for receiving the input signals and the outputs of the multipliers. The outputs of the summing means correspond to the orthogonal components of an output signal obtained by rotating the input signal through a given angle.

Abstract: A control method of a DC motor is described which comprises a digital control method and an analogue control method, wherein a rotor of the DC motor rotates with high speed under the digital control method until the rotating angle of the rotor comes close to a predetermined rotating angle and then the rotor rotates with high accuracy under the analogue control method to the predetermined rotating angle.

Abstract: Pointwise positioning apparatus for positioning a movable assembly includes small strip defining a series of positions corresponding to an electrical absolute position coding which co-operates with a movable assembly to produce a pulse signal when the movable assembly is or passes a predetermined coded position. A general control motor is coupled mechanically to a step motor, and a logic circuit actuates the general control motor until a first passage through the predetermined position, whereupon the general control motor is actuated in the opposite sense until the movement of the movable assembly reverses, and then the step motor is actuated until the movable assembly again reaches the predetermined position.

Abstract: Electronic ramp function generator having a resolution of 2.sup.p = 2.sup.q .times. 2.sup.r comprising a coarse digital function generator which provides a ramp consisting of 2.sup.q equally spaced steps all of equal height, and a second and synchronized digital function generator which is connected to fill in each of the steps of the coarse ramp with 2.sup.r finer steps.