Abstract: A dynamic vibration absorber for reducing vibrations of a platform induced by an oscillating mass mounted thereon is provided by mounting a mass of equal mechanical resonant frequency as that of the oscillating mass and oscillating this mass in a manner to establish an equal and opposite vibration of the platform, thereby cancelling the vibrations induced by the oscillating mass. In one embodiment, a signal from the oscillating mass representative of the frequency and amplitude of its mechanical oscillation is phase shifted and utilized as a driving signal to the drive motor of the absorber mass. In another embodiment, electrical signals representative of the platform vibrations are detected to provide phase and amplitude vibration error signals. These error signals are applied to a reference signal coupled to the drive motor of the canceller mass causing the oscillations of the canceller mass to induce vibrations in the platform which counter the vibrations induced by the oscillating mass.

Abstract: The mechanical stabilization system for a support comprises a working rotor mounted on the support by means of bearings and fixed to a working member having at least one parameter associated with the rotation of the working member and which is variable as a function of time. A reaction rotor is concentric with the working rotor and is mounted on the working rotor by means of bearings and is fixed to a reaction inertia member. A first servo-controlled electric motor is interposed between the working rotor and the reaction rotor and serves to drive the working rotor and the reaction rotor in opposite directions of rotation. A low power second electric motor is interposed between the working rotor and the support and is servo-controlled in such a manner as to reposition the reaction rotor and correct for drift in the correcting motion of the reaction rotor, due in particular to friction in the bearings.

Abstract: An integration-proportional controller in a servo-control system comprises in one aspect, an integrator for integrating a deviation of an input speed reference signal from a feedback signal fed back from an object to be controlled, and a proportional amplifier connected with the integrator for amplifying the feedback signal, the integrator including a clamping function in which an output value therefrom and an initial value for the next successive integration are changed, when the output value as a result of integration of the deviation is out of a predetermined proper output region, to the nearest boundary of the predetermined region value.

Abstract: A torque control unit rotates a motor machine having a motor element and a load element. The load element is coupled to the motor element via a rotational main shaft and driven to rotate by the motor element. Rotational acceleration at each rotation angle during one revolution of the rotational main shaft is detected and fed back. An electromagnetic torque of the motor element is controlled so that a difference between the electromagnetic torque of the motor element and a load torque of the load element may become zero at each rotation angle of the rotational main shaft.

Abstract: A determination and control section of a process control system samples a set value, a difference value, a manipulated variable, and a controlled variable to determine a state of a process. When it is determined that the process is in an unstable state, an adaptive unit estimates a dynamic characteristic of the process, and calculate PID control parameters using a partial model matching method in a frequency region. When it is determined that the process is in an insufficient response state, the PID control parameter is regulated without operating the adaptive unit to decrease the gain of the process control system.

Abstract: To provide for fine-adjustment of the relative angular position of a driven body of rotation, such as a plate cylinder (1) of a printing machine, and having a driven shaft (21, 41) with respect to a driving shaft (9, 40), an axially shiftable intermediate shaft portion (14, 53) is positioned between the driving shaft (9, 40) and the driven shaft (21, 41) and the body of rotation, respectively. An elastic coupling structure (16, 24; 55, 57), for example a composite stacked leaf spring, and having the characteristic of being circumferentially stiff but axially flexible, couples the intermediate shaft, for axially shifting movement, between the respective shafts. Preferably, two such elastic coupling structures are provided.

Abstract: A system for controlling temperature of air to be discharged into a cabin of a vehicle in an automatically controlled air conditioner system of an automotive vehicle. The air conditioner system is provided with a cooling unit and a heating unit for cooling and heating conditioning air in the air conditioner system for delivery to the cabin of the vehicle. The air conditioner system includes a mechanism for mixing the cooling air and the heating air in a stepwise manner so as to generate a controlled temperature of conditioning air to be discharged into the vehicle cabin with a moderate adjustment in transition so as to maintain a desired vehicle cabin temperature.

Abstract: A device for controlling positioning of a movable object includes a system for storing therein a provisional target position for the movement of the movable object, the storing system being arranged to store therein the provisional target position by providing an offset with respect to a final target position at which the movable object is to be finally positioned, and a control unit for controlling movement of the movable object, the controlling unit being effective to move the movable object so that, at least during a particular section of the movement, the movable object aims at the provisional target position, and the controlling unit being also effective to introduce, at a predetermined timing, the final target position so that the movable object is moved while aiming at the final target position.

Abstract: The control loop instability detection and correction apparatus monitors an error signal produced by a control system to detect any instability in the control loop before the instability significantly affects the performance of the controlled apparatus. This is accomplished by monitoring the error signal to detect a change in the error signal greater than a predetermined limit and to tabulate the number of times the change in the error signal is in excess of the predetermined limit over a fixed period of time. Whenever the change in the error signal is in excess of the predetermined limit, it is reduced in magnitude to a predetermined value and this resultant signal is applied to the controlled apparatus in place of the originally generated error signal. In addition during each sampling time interval, the result of this comparison is used to increment or decrement a counter.

Abstract: Described is a novel technique and associated arrangement for determining the noise-free value of a system parameter (e.g., head position in a disk drive) which is time variable and (usually) has a noise component as detected. The technique involves processing the (as detected) noise-including value and passing it through "Second Order/Summing" filter means.For instance, the technique is described as particularly useful with the "track-following servo" (part of the transducer positioning means) in a high density disk file (where track density is higher than usual) to secure superior head-displacement error values which are more noise-free. Thus, (see FIG. 4), a pair of first values V.sub.a, V.sub.b are secured by detecting motor current sense voltage V.sub.i, integrating it with respect to time and passing the result through a pair of novel "second order filter" means--one hand-pass (F.sub.1) the other low-pass (F.sub.2); while also securing a third value V.sub.

Abstract: A negative feedback control system includes a step of amplifying digital information by an amplifying operation at a high response speed and not including an integration. The negative feedback control system detects a predetermined amount of increase and decrease in the controlled variable, and outputs an increment signal or a decrement signal according to the predetermined amount of increase and decrease in the controlled variable, respectively, receives increment signals and the decrement signals from a controlled variable detecting unit 4, ignores the first successive n increment signals immediately after an arbitrary decrement signal, then begins to count each increment signal as a +1 unit from the n+1-th increment signal after the arbitrary decrement signal, and ignores the first successive n decrement signals immediately after an arbitrary increment signal, then begins to count each decrement signal as a -1 unit from the n+l-th decrement signal after the arbitrary increment signal (FIG.

Abstract: Method and apparatus for providing selfadaptive feedback control loop bandwidth and phase margin regulation automatically, to rapidly and predictably closely compensate for externally-caused bandwidth and phase margin changes, such as caused by changing load inertia presented to an actuator. Regulation is effected by controlling a loop-bandwidth correcting compensation element whose change is rendered equal to that of the loop affecting external change, but opposite in phase and change in magnitude. In a preferred embodiment, a correcting apparatus is within an internal feedback control loop which, by automatically compensating against a stated allowable range of uncorrected bandwidth variation, provides uniform static and dynamic bandwidth regulation for both internal feedback control loop and, therefore, regulation of the feedback control loop bandwidth and phase margin.

Abstract: A machine positioning apparatus and method are disclosed in which motor control values are established by causing intentional overshoot of the destination, and automatically reducing the motor control values each time an overshoot occurs. The system disclosed is a three stage system in which: (1) the first stage is a continuation motion relatively fast stage wherein the motor control values relate to the distance traveled; (2) the second stage is a much slower stage in which a series of interim targets are set, each of which is at a distance from current position which is a fraction of the remaining distance to destination, the motor control values during the second stage being motor duty cycle values; and (3) the third (final) stage is the slowest and involves setting a series of interim targets to be passed, each of which is substantially the current position, the motor control values during the third stage being motor duty cycle values.

Abstract: The present invention relates to a control system for a servomechanism device such as robot, and more particularly to a position correcting control system for a servomechanism device which is well suited to perform high-precision positioning or high-perfomance operations on the basis of a sensor feedback control system such as force detection feedback control.

Abstract: The present invention is a device for compensation of electric transfer functions of electric or electronic sensors (G), detectors, instruments or four-poles. According to the invention, the signal from the unit (G) to be compensated is connected to a differential amplifier (D) with a feed-back network (Z) having a transfer function that is substantially the same as the transfer function to be compensated. The compensating device has a transfer function that approximately is inverse to the transfer function of said sensor (G). The signal that the sensor senses and that is distorted by the nonlinear transfer function of the sensor is then restored. The feed-back network can either be passive or consist of electrically controllable active filters.

Abstract: A servo-control system is provided for the steerable front wheels of a vehicle, particularly the steerable nose gear of an aircraft, at least the lower part of which having at least one wheel may rotate about its longitudinal axis. This system includes a high pass filter device whose input receives a signal containing at least a part representative of the oscillations about its longitudinal axis to which said lower part of said nose gear is subjected and whose output is connected to a device for subtracting the output signal of said high pass filter from said difference between said order and said signal representative of the real orientation, and the pass bank of said high pass filter covers the natural oscillation frequency of said lower part of the gear about its longitudinal axis.

Abstract: A feedback servo positioning system for motor 13 is configured under the control of microprocessor 27 either as a position feedback servo for small displacement demands or an acceleration feedback servo for large displacements. In the latter role, the processor determines an intermediate position (e.g. mid point), accelerating the motor at maximum acceleration rate until the intermediate position is reached, and then calculates the deceleration rate required to stop the motor at the demand position. During deceleration the instantaneous position and velocity are monitored to update the optimum deceleration rate to compensate for variations from the initially computed value due to friction and other measurement errors.

Abstract: A stabilization aid for a vehicle- or vessel-borne search unit comprises two servomechanisms for stabilizing the observation part (3) of the search unit about two mutually perpendicular axes (S.sub.1 and S.sub.2) mounted on the part of the search unit which rotates about the search axis (1). The stabilization aid comprises a computer (7) for determining, from the instantaneous angle of inclination (.alpha.) of the platform (2) supporting the search unit with respect to an earth-fixed reference axis and the instantaneous angular position (B) of the search unit about the search axis (1), measured in the plane of the platform (2), input signals for the servomechanisms. A portion of these input signals are compensating signals for the control errors in the servomechanisms.

Abstract: A rotational position, velocity and acceleration of an electrical motor are detected and an amount of overrun produced when the motor has stopped is estimated from the detected velocity and acceleration, and at least one of motor position detection data and a positioning target value is changed in accordance with the estimated amount of overrun. The position detection data and the positioning target value after the change are compared with each other and a command for stopping the motor is generated in accordance with a result of this comparison. A brake is applied to the motor in advance by the amount of the estimated overrun so that the motor is stopped at a desired target position after making overrun. Further, velocity setting signals are generated in accordance with desired acceleration and deceleration characteristics and the velocity control of the motor is effected in an open loop in response to the velocity setting signals.

Abstract: A high gain feedback control system is disclosed which is capable of stably operating without exhibiting any unstable phenomena such as natural frequency. The control system comprises a high gain controller, a controlled system, a detecting means and a summing point, and is constructed in a manner that the detecting function has a transfer function determined to allow a loop transfer function of the control system to have (n-1) zero points when the loop transfer function has n poles, to thereby permit the transfer characteristics to compensate for the transfer characteristics of the controlled system with a time lag. Also, a high gain multi-loop feedback control system is provided which is capable of exhibiting such advantages.

Abstract: A servo system 10 (FIG. 1) for positioning a sighting mirror 11 connected to a pulley 16 comprises a drive motor 13 rigidly connected to a drive pulley 15 in turn coupled by a tensioned drive belt to the pulley 16. Angular position of the motor or pulley 15 is measured by sensor 18 and passed by way of phase advance network 19 and amplifier 21 to produce an error signal for the drive motor. The pulley 16 is outside of the servo loop and any oscillations induced in the tensioned belt at its resonant frequency, possibly originating from electrical noise in the servo loop, will be uncontrollable.

Abstract: When an unusual condition of a wheeled vehicle such as nose-diving caused by braking, squatting caused by an abrupt start or rolling caused by a turn is sensed, the damping force or the spring constant of each suspension unit, which serves as a shock absorbing unit, is temporarily increased to correct the position of the vehicle. The increased damping force or spring constant is maintained a predetermined period of time even after the unusual vehicle condition is settled, thereby preventing the vehicle body from tossing back due to the force of inertia.

Abstract: An electrohydraulic servo control system responsive to a load acceleration or velocity command input signal wherein the input command signal is integrated and compared with position feedback from the valve actuator and load to obtain an error signal which controls the actuator. The velocity command input may be multiplied by an exponential factor to compensate for system following error. Another modification contemplates resetting of command signals to compensate for following error and to eliminate dead time upon change of direction of the load by the operator.

Abstract: A servomotor controller provides high speed servomotor positioning be means of an on line adaptive state-feedback control algorithm. Servomotor position and velocity are the feedback states and each has an associated gain selected by means of a servomotor characterization scheme. The mechanical break frequency is used to select optimum gains and a high speed estimation technique is used to determine the mechanical break frequency. Position step change may also be used to select optimum gains. Gain tables are produced by an off-line simulation technique.

Abstract: A system and method are disclosed for precisely positioning a movable member to a desired fine position after a selected coarse position is reached. In a preferred embodiment of the invention a processor-controlled typewheel servo control system is responsive to a command signal for a selected coarse position for selectively utilizing from a memory circuit preselected stored adjustment information for the selected coarse position comprised of an associated coarse position count and quadrant information related to the sinusoids generated by an optical encoder in order to make a precise fine position adjustment in the position of a typewheel after the selected coarse position is reached for that typewheel.

Abstract: A position control apparatus has a variable gain-type velocity amplifier (115) provided within a servo control circuit, and a low velocity sensing circuit (114) for sensing a predetermined low velocity of a motor (100) immediately before the motor is stopped. When the rotational velocity of the motor (100) drops to the predetermined low velocity immediately before stoppage during orientation control, the velocity amplifier is changed over in response to a signal from the gain of the low velocity sensing circuit (114), thereby raising servo loop gain.

Abstract: A first stage adapted to be moved in predetermined directions by a first driving device is provided in a machine base supported from a foundation by an intermediary of resilient means. This first stage is provided a second stage adapted to be moved in the directions at right angles to the directions of movement of the first stage by a second driving device. Upon movement of these respective stages, vibration of the machine base is excited by reaction forces exerted upon the machine base as a result of acceleration and deceleration. These reaction forces are offset by resistive forces generated by first and second force generators respectively. The first and second force generators establish an electromagnetic coupling between the foundation and the machine base.

Abstract: An object of the invention is to provide variable damping for resonant vibrations which may occur at different rotational speeds in the range of rpms in which a rotating machine is operated.A variable force damper in accordance with the invention includes a rotating mass (12) carried on a shaft (11) which is supported by a bearing (13) in a resilient cage (14). Cage (14) is attached to a support plate (15) whose rim extends into an annular groove in a housing (17).Variable damping is effected by tabs (18) of electrically conducting, non-magnetic material which extend radially from the cage (14). The tabs (18) at an index position lie between the pole faces of respective C-shaped magnets (19). The magnets (19) are attached by cantilever spring members (20) to the housing (17).By rotating the support plate (15) about the axis of shaft (11), the tabs (18) may be rotated through an angle 0 of about 40.degree. away from the index or 0.degree. position. At the 40.degree. position minimum damping is obtained.

Abstract: A disk drive control circuit designed to eliminate undesirable mechanical resonances that occassionally occur in the disk drive system as a result of a particular combination of seek commands. The control circuit uses an electrical model of the mechanical system in order to estimate or predict whether a particular seek command is likely to excite a mechanical resonance. The electrical model may be a filter network having frequency response characteristics similar to the mechanical system. The current used to drive a linear motor of the mechanical system is then applied to the filter network. The signal output from the filter network, which network effectively models the mechanical system, is thus representative of the mechanical response of the system upon performance of the seek operation. This signal output is monitored, and if it exceeds a predetermined threshold level, steps are taken to alter the system response so as to avoid exciting the mechanical resonance.

Abstract: The regulation range of a conventional bang-bang current regulator is extended by altering the current command or feedback signals to cause the feedback signal to exceed the command signal sooner in time than it otherwise would and fall below the command signal later in time than it otherwise would. For relatively low command signal values, the current is regulated in a discontinuous series of reduced peak excursion pulses, enabling the average value of current to be regulated down to a lower value than possible without the alteration.

Abstract: Electronic compensation apparatus for modifying an input control signal, to produce a drive signal for a torque motor of an electrohydraulic servovalve. The torque motor has a frequency variable response characteristic. The apparatus includes means to determine a first voltage magnitude across the armature of the torque motor when it is not moving; means to determine a second voltage magnitude across the armature of the torque motor when it is moving; and means to determine a difference voltage of the first and second voltages. The difference voltage measures the dynamic motion of the armature and provides a feedback control signal. The apparatus further includes compensation means responsive to the feedback control signal for compensating the electrohydraulic servovalve so as to avoid resonance, and feedback means connected to the compensation means for providing a modified control signal.

Abstract: The control circuit employs a controller having an I-member and a servo-motor whose rate of adjustment is limited and which is associated with a follow-up. The follow-up enables the operative movement of the servo-motor to act on a comparator in the control circuit between the output of the controller and the input of the servo-motor. The output of the comparator is also connected to attenuating means which are operative in the entry path of the I-member. The attenuating means includes a functions pick-off and a multiplier element. The functions pick-off delivers an output signal which is lower for a high absolute value of its input signal than for a low absolute value. This output signal acts via the multiplier element on the entry path of the I-member.

Abstract: A position control device for controlling a position of a movable member has high durability and is free from a hunting phenomenon. Electric contacts arranged in a row at a given pitch are respectively connected to the nodes between series-connected resistors and first and second brushes interlocked with the movable member can contact the adjoining two of the electric contacts at a time such that discrete two voltage signals are generated at the first and second brushes. A pair of comparators compare these voltage signals with a voltage signal corresponding to a target position where the movable member is to be stopped and a driving means for the movable member stops its operation when the former voltage signals sandwitch the latter voltage signal.

Abstract: A method of stopping a DC motor at a predetermined position by causing the motor to hunt the predetermined position following an overshoot. After each overshoot the applied DC motor drive voltage is reversed in polarity and diminished in magnitude to damp the rotative energy until the motor stops at the predetermined position.

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: Automatic Process Control Device having input transistors to receive process and set point signals; a subtractive amplifier to compare the process and set point signals and produce one of two amplified deviation signals which are limited to maximum values by zener diodes; capacitors to receive, time-integrate and store the amplified and limited deviation signals, and produce a neutral output if the time-integration of the amplified and limited deviation signals is in balance, and one of two trigger signals if the time-integration of the amplified and limited deviation signals is positive or negative; and relay switches connected to discharging circuits and in series with zener diodes to receive the trigger signals and operate a controlling device upon the process to urge the process toward its desired set point, and simultaneously produce a corresponding tripping signal which urges the capacitors toward a status to produce the neutral output, such that as the controlling device is operating upon the process t

Abstract: A system for controlling the rotation of a spindle which includes motor, a speed detector for detecting the speed of the motor and for producing a signal indicative of the actual speed thereof, a speed control circuit for controlling the motor so as to narrow a deviation between the signal indicative of the actual motor speed and a command speed signal, a spindle which is driven by the motor, and an orientation control circuit for producing a position deviation signal on the basis of the rotational position of the spindle and a commanded stopping position, wherein the spindle is rotated at a commanded speed by the speed control circuit and rotationally controlled in response to an orientation command signal so as to reduce the position deviation signal to zero.

Abstract: An automatic control system in which a controlled quantity of an object to be controlled is compared with a preset quantity through a comparator, the output signal of which is applied to blind controller means having a dead zone set therein. When the output from the comparator comes out beyond the dead zone, the blind controller means cooperates with operation holding means to perform a control operation continuously for a predetermined time even when the output from the comparator falls within the dead zone. The number of times at which the object is controlled may be significantly decreased.

Abstract: Disclosed is a control circuit of a positioning device for moving a member to be controlled to a predetermined position by using a d-c motor, in which there are used arithmetic circuit means for detecting a difference signal, to be converted to a driving signal of the motor, between the position detecting signal of the member and the reference signal of the predetermined position, and correcting circuit means coupled to the arithmetic circuit means for causing the difference signal to be small, whereby the motor is free from the hunting phenomenon.

Abstract: A digital control circuit for use in automatic-focus cameras is disclosed, which is suitable for use in self-focusing systems which determine focus by means of triangulation. The system corrects for motor oscillation about a state of proper focus, defocusing caused by inertia, and for an inability to evaluate proper state of focus caused by large distances between the camera and a subject.

Abstract: A stepping motor system is shown wherein a method is employed for determining the optimum amplitude of the current supplied to the stator winding of the motor. A series of different currents are applied to the motor. First, the stator windings are energized with currents of certain base magnitudes. Then the current in one winding is increased by a small amount and the current in the adjacent winding is decreased by a small amount so that the rotor tends to move towards its new equilibrium position. When the rotor reaches its maximum displacement the current changes in the windings are reversed so that not only will the rotor "hunt" for its new equilibrium position but it overshoots with twice the magnitude. This process continues for a certain period of time during which the oscillation magnitudes rapidly grow. In one embodiment, after a maximum amplitude is reached, the current changes are applied out of phase with the oscillations to now try to decrease their amplitude.

Abstract: A method and control apparatus are disclosed for maintaining a measured parameter of an environment in a closed-loop system within a range of the desired level for that parameter, to an accuracy greater than that of the parameter measuring device in the closed-loop system. The control apparatus periodically receives measurement readings of the parameter to be controlled from a sensor, having a fixed measurement accuracy. An adjustable length memory stores a historical value of changes between the periodically obtained parameter measurements that have occurred over a predetermined length of time. The control apparatus and method generates a control signal for regulating a prime mover acting on the environment which affects the measured parameter, by combining the historical value change data stored in the memory with the difference between a current parameter measurement and the desired parameter value.

Abstract: A method and apparatus for driving a stepping motor by angularly displacing the revolvable magnetic field with respect to the rotor by a first displacement angle in a given direction of revolution and then revolving the revolvable magnetic field, preferably with linearly increasing velocity and therefore maintaining constant displacement angle between the field and the rotor until the rotor rotates at a second velocity.

Abstract: The operational range of an adjustable focus lens is subdivided into a plurality of focus zones, of finite size, by a lens control system that produces a plurality of discrete signals representative of said focus zones, said control system utilizing bidirectional drive means to position the movable element of said lens to one of said focus zones from any position within said operational range in order to focus an image of a remote object at an image plane. The present invention optimally increases the focusing of said control system while equalizing and minimizing the focusing error introduced into said control system resulting from the use of such focus zones with bidirectional drive means, by anticipating the arrival of said movable lens element at the desired focus zone and then interrupting the driving force provided by said drive means for a limited period of time prior to the time that said lens element arrives at said desired focus zone.

Abstract: The operational range of an adjustable focus lens is subdivided into a plurality of focus zones, of finite size, by a lens control system that produces a plurality of discrete signals representative of said focus zones, said control system utilizing bidirectional drive means to position the movable element of said lens to one of said focus zones from any position within said operational range in order to focus an image of a remote object at an image plane.

Abstract: Disclosed is a system and method for controlling the motor drive for positioning a workpiece on a compound slide in such a way that the workpiece arrives at the target position in minimum elapsed time and without overshoot. A fixed program memory, in conjunction with a comparator and a combiner, is used to process information as to the actual position and velocity of the body and the desired position and velocity of the body to determine the optimum torque for the motor. The memory includes information as to the control characteristics of the motor and the desired path yet to be traveled to the target position.The method of positioning comprises the steps of controlling the motor so that it runs initially at maximum torque in a first region, at less than maximum torque and in the same direction in a second region, and then at yet another torque magnitude and with the torque in the opposite direction in a third region.

Abstract: The drive shaft of a motor can be coupled to an output shaft by an electromagnetically activated friction clutch. The output shaft can be braked by an electromagnetically activated friction brake. The motor drive shaft rotates at constant speed. The rotary speed of the output shaft is regulated by negative-feedback action to maintain a selected value, by activating the clutch and brake alternately as necessary. The activating signals for the clutch and brake are pulse-width-modulated activating signals. The output shaft can be stopped in at least one predetermined angular position when commanded to do so. The movable parts of the brake and clutch are of minimal mass, and the speed-regulating system includes a speed feedback transducer system of very high resolution.

Abstract: A system for controlling the amplitude of a drive signal applied to a stepping motor in a manner minimizing the effects of resonance on the resultant angular velocity of the motor shaft. Means are provided for comparing a desired motor drive frequency against one or more known resonant frequencies and, responsive to such comparison, for producing a motor drive signal at an amplitude predetermined to minimize oscillatory fluctuations in the motor shaft velocity.

Abstract: A digital servo system is described in which hunting that would be caused by restoring torque due to resilient coupling to a load is prevented by preventing the transfer of information from the error register to the D/A converter controlling the motor.

Abstract: The operational range of an adjustable focus lens is subdivided into a plurality of focus zones, of finite size, by a lens control system that produces a plurality of discrete signals representative of said focus zones, said control system utilizing bidirectional drive means to position the movable element of said lens to one of said focus zones from any position within said operational range in order to focus an image of a remote object at an image plane.