Abstract: A torque shudder protection device for an induction machine includes a flux command generator for supplying a steady state flux command and a torque shudder detector for supplying a status including a negative status to indicate a lack of torque shudder and a positive status to indicate a presence of torque shudder. A flux adapter uses the steady state flux command and the status to supply a present flux command identical to the steady state flux command for a negative status and different from the steady state flux command for a positive status. A limiter can receive the present flux command, prevent the present flux command from exceeding a predetermined maximum flux command magnitude, and supply the present flux command to a field oriented controller.

Abstract: Active magnetic bearings supporting a rotor operated at high speeds is controlled by a controller. Tracking filters provided in the controller pick up forward vibration components in synchronism with the rotational speeds from the displacement signals of the rotor, and a mode separating circuit provided in a mode gain controller takes out displacements of the 3rd and 4th modes. Then, a gain controller provided in the mode gain controller determines suitable gains for the separated displacement signals. A mode synthesizing circuit provided in the mode gain controller synthesizes a controlled variable for each of the bearings from the control signals that are processed for the respective modes. By adding the control variable to the respective bearings, the vibration amplitude is suppressed in critical speed zones of high orders, and the rotor is stably operated up to a high-speed range.

Abstract: A method and apparatus used with a motor controller that detects load imbalance at a relatively low speed and, if the degree of load imbalance is greater than a predetermined acceptable maximum degree, produces an alarm signal that indicates an imbalanced load. If the degree of load imbalance is greater than the predetermined acceptable maximum value, the present invention may either attempt to rebalance the load or stops the motor until the balance can be manually adjusted.

Abstract: A position control circuit having a demodulator with automatic tuning capability for use in an electro-hydraulic positioning system used to position a servo device. The position control circuit includes the demodulator, an analog to digital converter with an input voltage range, and a microcontroller. The demodulator has a gain and is operable to convert a feedback signal from the servo device to a position signal having a lower voltage value when the servo device is at its 0% position and an upper voltage value when the servo device is at its 100% position; the lower voltage value and upper voltage values being a function of the demodulator gain.

Abstract: The value of a variable reflecting the operating condition of mechanical equipment is continuously detected as operation condition data. A long period average value of the operating condition data detected in long reference period, and a short period average value of data detected in a short analysis period ending in the present time are calculated. Just how much the short period average value differs from the long period average value is adopted as an index of abnormality and using this index, it is possible to ascertain abnormal operating conditions regardless of the absolute value of the variable detected. The above short period average value, long period average value and standard deviation thereof are applied to a first fuzzy membership function for calculating the degree of stability of the mechanical equipment therefrom.

Abstract: A stage driving system capable of positioning an object with a higher speed and a higher precision than prior systems. The system includes a base member, plural movable members provided on the base member, and a controller for controlling the plural movable members so as to substantially suppress the vibration of the base member caused by the displacements of the plural movable members.

Abstract: A hard disk drive that contains a detection circuit which senses the back emf of a voice coil. The detection circuit generates a shock detection signal when the back emf of the voice coil exceeds a pre-determined value. The write disable gate of the disk drive is disabled when the voltage detection circuit generates the shock detection signal.

Abstract: A position command method and apparatus for shortening the acceleration and deceleration times of a servo controlled apparatus by effectively utilizing the torque of the controlled apparatus. A value of speed per unit time is developed on the basis of speed and position data, and a constant speed or an acceleration or deceleration function processing may be selectably performed. In the position commanding method and its unit of the present invention, the deceleration stop distance of output speed is computed at all times or is held as a list data as described above and moreover is compared with a residual distance XR. Consequently, the deceleration stop distance does not have to coincide with the residual portion from the acceleration command, and the acceleration/deceleration curve alone can be realized in an independent form. Also, the speed change can be made smoother by correcting the cross point of independently formed acceleration and/or deceleration curves defining a corner section.

Abstract: An interchangeable lens unit for use in a camera system which is arranged to drive a motor in the interchangeable lens on the basis of a signal supplied from a camera body. The interchangeable lens unit is provided with a circuit for continuously transmitting a specific signal to the camera body for at least the time period required to absorb a backlash when the direction of running of the motor is reversed with respect to the preceding direction of running of the same.

Abstract: Methods and apparatus for providing improved gain and bandwidth and robust damping of mechanical resonances for a servo control system by providing a collocated or nearly collocated feedback loop that operates in parallel with the ordinary feedback loop used for position or velocity feedback.

Abstract: Flux information in a magnetic circuit such as may be used for rate damping and vibration suppression in a magnetic forcer system is sensed and is used in conjunction with a differentiated forcer position signal to provide a rate damping signal. The sensed magnetic flux is used to synthesize an inertial velocity signal which is applied as a position rate damping input to a closed position control loop.

Abstract: A control system having a source of control signals and a multi-window electrical signal tracking filter. The signal tracking filter includes an operational amplifier operating in the non-inverting mode as a high impedance load, with a plurality of input stages cascaded at the input to the operational amplifier, each input stage having both a frequency determining filter portion and an amplitude determining threshold detecting portion. Each input stage defines a "window" of operation, such that the portion of a control signal or the like inputted to the filter which falls within the "window" will be filtered or attenuated thereby, while the portion of the control signal which falls outside of the "window" will pass unaffected through the filter. Cascading of the input stages allows one to customize the portions of the signal to be filtered for any particular application.

Abstract: An electronic damping system is disclosed which dampens mechanical resonant vibrations of a gantry beam end. The system includes a secondary velocity feedback loop in addition to the main servo motor-tach velocity loop. The resonant velocity of the beam is sensed from the movement of the end of the beam. The velocity feedback signal is summed as negative feedback with the velocity command signal from the position controller. The resultant sum of the signals are combined to form the velocity reference input command signal to a servo power amplifier. The servo power amplifier is connected to a main servo motor which controls the movement of the gantry beam in the Y-direction relative to printed circuit board.

Abstract: A positioning control apparatus for accurately positioning a tool and workpiece and for reducing the vibration related to positioning. The system comprises a machining table fitted with a workpiece and designed to be movable on a bed. A first detector detects the acceleration of the machining table in a moving direction, and a second detector detects the acceleration in the moving direction of a tool fitted to a column that also is coupled with the bed. The outputs of the first and second detectors are used to suppress the relative vibration of the workpiece fitted to the machining table and the tool fitted to the column in the moving direction.

Abstract: A machine with a movable element, such as a machine tool and its spindle carrier, that is powered by a motive means to move the element is provided with a counterbalancing system having at least two counterforce means operably connected to the movable element for exerting a counterbalance force on the movable element in opposition to the first force and wherein a first one of the counterforce means has a controllable servomotor means. The control means controls the servomotor means so as to cause the counterbalancing system to exert a substantially constant counterbalance force on the movable element in opposition to the first force. The second one of the counterforce means may be a hydraulic means having a hydraulic cylinder operably connected to an accumulator and a hydraulic piston operably disposed in the cylinder and connected to the movable-element.

Abstract: In a servo loop closure for an aircraft control surface, surface position from the control surface synchro is utilized to augment the servo motor rate feedback so as to reduce limit cycle oscillation. The high frequency content of surface position is suppressed by substituting a percentage of the low frequency content thereof for the same percentage of low frequency servo motor rate. This arrangement reduces control column activity normally associated with high effectiveness ratios of surface position for servo motor rate substitution.

Abstract: Dimpling of a workpiece by rebounding of a magnetic repulsion punch mechanism, when operated at high punching rates, is avoided by application of a damping pulse at a point at or subsequent to a mid-point of a return stroke of the punch from the workpiece and preferably within the last 10% of the return stroke. This damping pulse is preferably a fraction of the pulse width and of approximately the same amplitude as a driving pulse applying kinetic energy to the punch for causing punching of the workpiece. At high punching rates the kinetic energy of the return portion of a punching stroke is substantially determined by elastic rebounding of the punch from a guide bushing. The removal of kinetic energy during the return portion of the stroke allows the return of the punch to a position close to a rest position during a very short interval with small overshoot under control of mechanical damping.

Abstract: A motor servo system for controlling a motor includes a first synthesizing portion which synthesizes a speed detection signal and a phase detection signal with each other to produce a synthesized signal which is in turn filtered by a low-pass filter portion and then becomes a first motor control signal. The first motor control signal is applied to an equivalent motor portion (software motor) which is included in an observer and has a transfer function of as the same as that of the motor. A detection signal which is detected by the equivalent motor portion and a synthesized signal from the synthesizing portion are compared with each other by a first comparing portion. An output signal of the first comparing portion is applied to a second comparing portion or a second synthesizing portion.

Abstract: A control system having proportional and integral functions for controlling the rotational speed of a motor. The system includes a self-limiting integrator for avoiding or limiting integral wrapup, a problem commonly associated with integral control. The self-limiting integrator includes an integrator, limit comparator, OR gate, delay circuit, and sign reversal circuitry. The integrator reverses direction of integration when an error limit is realized. The error limit, a preestablished and adjustable value, can be used to determine the rise and settle time of the speed of the motor independently of the gain.

Abstract: A sliding mode control method is provided capable of improving the following ability of a control system with respect to a command at the time of change in the operating condition of a machine, and preventing vibration which tends to occur by the action of a spring element of the machine at the time of change in the operating condition. The processor of a servo circuit derives position deviation (.epsilon.) and speed deviation (.epsilon.) based on a command position (.theta.r) and an actual position (.theta.), estimates an torsion amount (.epsilon.n) and torsion speed (.epsilon.n) by effecting observer processing (Steps 100 to 101), and derives a switching variable (s) (102).

Abstract: Disturbing forces, such as linear forces or torques, exerted on a structural member 12 of an inertially servoed structural interface placed between two assemblies are nulled by the application of a responsive corrective inertial force or torque to the structural member. The force on the structural interface is sensed by a force sensor associated with the member. In an embodiment of the present invention for nulling linear disturbing translational forces, a servo control loop 18 is responsive to a linear translational force sensor and drives a linear actuator 22 that applies a corrective inertial linear translational force to the structural member 12 so as to null the force exerted thereon. In an embodiment of the present invention for nulling torsional disturbing forces, the servo loop 18 is responsive to a torsional force sensor 44 and drives a torque motor 42 that applies a corrective inertial torsional translational force to the structural member 12 so as to null the force exerted thereon.

Abstract: A digital servo control loop for a disk drive head position actuator implements a multi-rate notch filter in order to eliminate actuator resonances at frequencies above the sampling rate Nyquist frequency. The control loop includes circuitry responsive to the periodic digital position values sampled from embedded servo sectors which generates and puts out digital control values at the predetermined sampling rate for controlling the position of the actuator means. A digital multi-rate notch filter receives and filters the digital control values, and generates and puts out notch filtered digital control values to the actuator means at a rate comprising an integral multiple of the predetermined sampling rate.

Abstract: An oscillatory servo-valve fault monitor is provided for identifying faults attributable to servo-control system components. In particular, both low frequency and high frequency (oscillatory) fault responses are identified. Such oscillatory fault responses are distinguished from normal position control adjustments and transient responses. As the reaction to a fault condition is to shut down the faulty actuator and corresponding servo-control, such capability avoids inadvertent shut-downs. Independent detection paths are provided for sensing low frequency responses and high frequency responses. Each path includes a respective window comparator and up-down counter. For a given path, the window comparator defines two thresholds--in effect, a window. If the monitored signal amplitude is outside the window, then a counter or count signal is incremented. If the signal amplitude is within the window, then the counter or count signal is decremented.

Abstract: A feedforward control method having an improved follow-up characteristic with respect to commands in a servo system and capable of a servomotor to operate smoothly and stably, is applied to a servo system in which a position/speed loop process is executed a plurality of times within one move command distribution period of an upper-level control device. A provisional speed command, which is the product of a gain (Kp) and a deviation (e) between an actual amount (Pf) of rotation of the motor and a move command (a) for each position and speed loop processing period, is corrected by a position feedforward quantity, which is the product of a coefficient (.alpha.1) and a mean value of move commands including the move command for each processing period and those before and after the present processing period calculated by a smoothing circuit to obtain a speed command.

Abstract: Machines having torques variable as a function of the angle of rotation such as piston driving mechanisms like compressors, cam driving mechanisms, printing machines and looms, are driven by an electric motor in such a way that a trend in angular velocity which is dependent upon the angle of rotation, in particular also a constant angular velocity of the main driving shaft (2) of the driven machine, may be predetermined. To do this the angle of rotation (3) as well as the torque (4) are picked up off the main shaft (2) and fed to an adaptive control system (S) which, starting from the desired values (s0) of the angular velocity as a function of the angle of rotation, applies a corresponding correcting variable (Y) to the electric motor (1) and iteratively adapts it periodically in order to bring the trend in angular velocity of the main shaft (2) into agreement with the desired value (s0).

Abstract: A device for insulating a body on magnetic bearings from vibration of its stator and hence the environment and vice versa. The body may include a rotor which can produce undesirable vibrations during rotation. The position of the body is caused to follow slow movements of the stator, but does not follow higher frequency interference. However, intentional fast position regulating procedures are possible. The device includes a double integrator which generates a largely interference-free position sensor signal for low vibration bearing adjustment which is followed slowly by a true position sensor signal. The device can be used in a flywheel for satellite stabilization where it facilitates adjustment of the angular position while at the same time providing insulation against vibration.

Abstract: An arrangement for stabilizing the line of sight in an optical tracking system relative to inertial space over a specified range of frequencies utilizing a mirror/torquer/pickoff subassembly both as an inertial sensor and as a control effector.

Abstract: A servo system for a motor having a rotor that includes a phase detector circuit for detecting a rotational phase of the rotor and for defining a plurality of angular positions of the rotor, each angle between adjacent angular positions being of the same size, a rotating device for rotating the rotor at a predetermined constant rotational speed, a speed detector circuit for detecting a rotational speed of the rotor at each of the angular positions, an error detector circuit for detecting errors of the speed detector circuit at each of the angular positions when the rotor is rotated at the predetermined constant rotational speed, a memory for storing the detection errors at each of the angular positions, and a servo control circuit for controlling a rotational speed and/or phase of the rotor in accordance with the rotational speed detected by the speed detector circuit and the detection errors read from the memory.

Abstract: To set the magnitude of the inertia of a motor and mechanical system or set gains suitable for the magnitude of vibrations of the motor and the mechanical system, the magnitude of a load inertia is identified in accordance with the time-integrated value of motor current to determine the gains of a feedback control loop in accordance with the identified value before executing feedback control in accordance with the determined gains.

Abstract: The invention relates to methods and arrangements for actuating electromechanical transducers, in particular electric motors (3) having a voltage or a current, the optimum curve shape of which is previously determined from the data of a model transducer and which data are stored in a function memory (30). In this way, a prescribed power or torque characteristic, for example without fluctuations, can be achieved.

Abstract: An abnormality detecting method for a servo system capable of quickly detecting an abnormal condition even in a low rotation speed range is provided.While a digital servo control section (11-13) is executes a servo control operation for controlling the drive of a servomotor in accordance with a torque command (Tc) derived from a speed feedback (VA) and a speed command (Vc) corresponding to an actual position deviation (Er), a simulator (14) integrates a speed command (Vcs) equal to the product of a position loop gain (PG) and an estimated position deviation (Ers) obtained by subtracting a position feedback (PAS) from a movement command (Me). The simulator thus derives the position feedback (PAS), and an excessive error detecting section (15) compares the difference (Er-Ers) between the actual position deviation and the estimated position deviation with a predetermined value (As).

Abstract: In a drive controlling apparatus, a driven body is driven by a motor, near to a target position in which the driven body is to be stopped, the speed is controlled on the basis of a deceleration curve characteristic memorized in a first memory means in response to the output of a first speed detector for detecting the moving speed of the above-mentioned driven body and, from near the above-mentioned target position, the speed is switched to be controlled on the basis of a deceleration curve characteristic memorized in a second memory in response to the output of a second speed detector for detecting the moving speed at a precision higher than that of the above-mentioned first speed detecting means.

Abstract: Rotating machine with a rotor (44) with an inductor of an electrical radial field machine (48) arranged on the rotor (44), which radial field machine is designed for absorption of the radial bearing forces acting on the rotor, and with an inductor of an axial field machine (46) arranged on the rotor (44), which axial field machine is designed for absorption of the axial bearing forces acting on the rotor. For normal force control, means for field control with the aid of current influencing are provided in the stators of the two electrical machines, which for their part are each subdivided into four quadrants with their own regulating units. The two electrical machines (46, 48) are of multipole design, there being at least two poles per winding quadrant. The axial field machine (46) is provided with three controllers for the stabilization of three degrees of freedom and the radial field machine (48) is provided with two controllers for the stabilization of two degrees of freedom.

Abstract: An actuator control loop for controlling head position in a rotating media data storage system. The invention applies the compensation zero to the PES prior to summing it with the integrator. This scheme reduces transients caused by the integrator initialization step because the zero does not "see" the integrator initialization step. Transients that can result from coupling the integrator initialization to the zero can cause overshoot and ringing in the actuator, increasing settling time and reducing system performance. The present invention also provides a first sample velocity compensation scheme that removes the velocity correction factor from the PES signal in the first sample after a seek. This significantly reduces settling time and improves system performance. In one embodiment, the microprocessor of the present invention calculates a velocity compensation factor based on the PES signal. This signal is then superimposed on the integrator output.

Abstract: A device for positioning control includes a movable stage; an acceleration sensor disposed on the movable table; a feedback loop for controlling movement of the movable table; and an acceleration feedback loop provided in relation to an acceleration signal from the acceleration sensor, wherein the acceleration feedback loop is provided as an internal loop to the feedback loop.

Abstract: A main feedback system regulates an output parameter of interest, such as velocity, versus a given range of load parameters, such as torque and inertia. An element feedback system rapidly adjusts an in-series-path zero to frequency track (cancel) a varying load-caused pole--including in-range variations of 100:1. Since zero-setting is inverse to an adjusted resistance required, a 100:1 zero range causes a highly non-linear resistance transmission, affecting the element loop's gain but not that of the main control feedback loop. By introducing a variable resistance of the same value as used in the main feedback system as a divider in the element feedback loop only, the element loop gain is made substantially constant over the entire pole-tracking range, and the element loop's bandwidth is made substantially constant over the same range, and thus rendering the dynamic response substantially constant over the same range.

Abstract: A numerical control unit for controlling the position of a movable part, such as a machine table, in response to input machining information. The unit employs a servo control loop that detects the values of the position, velocity, acceleration and motor current for the movable part at predetermined times. Using such detected values and, on the basis of a representative spring mass system model, values of inertia, mass, viscous friction and sliding friction can be calculated and used for automatically optimizing the gain and offset parameters applicable to control of the machine.

Abstract: Methods and apparatus for automatically identifying and adapting to changes in the overall gain of the mechanical plant in a digital servo control system to maintain a constant bandwidth.

Abstract: When a workpiece is cut or otherwise machined by a machine using a servo motor control apparatus having a position feedback loop, a velocity feedback loop, and a current feedback loop, it is the common practice to preset the instructed current value to a voltage corresponding to friction torque when rotation of the motor is started or reversed. This is to compensate for the response delay of the motor introduced by the friction torque. The present invention relates to improvements in this technique. After the instructed motor velocity changes from a positive value, to a negative value or vice versa, or after the detected motor velocity changes from a positive value to a nonpositive value or from a negative value to a nonnegative value, the value of the integration element of a velocity control portion is reversed according to a function. The obtained output value is added to the instructed current value or to the integration term to compensate for the response delay, thus reducing machining error.

Abstract: A velocity control apparatus in which velocity of a servomotor (12) is controlled by PWM-control of an inverter is so adapted that the gain (K') of an amplifier section (11) in a current loop is held constant by detecting the power supply voltage of the inverter.

Abstract: A non-linear dynamic compensation subsystem is added in the feedback loop of a high precision optical mirror positioning control system to smoothly alter the control system response bandwidth from a relatively wide response bandwidth optimized for speed of control system response to a bandwidth sufficiently narrow to reduce position errors resulting from the quantization noise inherent in the inductosyn used to measure mirror position. The non-linear dynamic compensation system includes a limiter for limiting the error signal within preselected limits, a compensator for modifying the limiter output to achieve the reduced bandwidth response, and an adder for combining the modified error signal with the difference between the limited and unlimited error signals.

Abstract: In a magnetic bearing system, the longitudinal shaft position is shifted relative to the bearing position so that a force can be applied by the bearings away from a node at critical shaft speeds. In one embodiment, the shaft is shifted by end thrust bearings back and forth on an integral cycle basis. Alternatively, closely-spaced bearing pairs may be used and energized alternately on an integral cycle basis in order to shift back-and-forth the region at which the combined effective force of the bearing is applied.

Abstract: A control system having an open loop transfer function G expressed by a transfer function G.sub.2 of one control component having at least one integration element and a mass transfer function G.sub.1 of other control components and a saturation level of the other components expressed by the transfer function G.sub.2 set lower than that of the component expressed by G.sub.1.

Abstract: The system for stabilizing a support comprises a working rotor mounted on the support by frictionless bearings and fixed to a working member for which at least one parameter associated with the rotation of the working rotor is variable as a function of time. A nested reaction rotor is mounted concentrically relative to the working rotor by frictionless bearings such as magnetic bearings or gas bearings and it supports a reaction inertia member. A single servo-controlled electric motor is interposed between the working rotor and the reaction rotor in order to drive the working rotor and the reaction rotor in opposite directions in such a manner that the torque disturbances generated on the support by the motion of the working rotor are cancelled by the simultaneous reaction motion of the reaction rotor, with the ratio of the speeds of the working rotor and the reaction rotor being such that the total angular momentum of the working rotor and of the reaction rotor is kept equal to zero.

Abstract: The position of a drive shaft of a printing press is regulated during acceleration of the printing press. A position regulator includes a first integrator and a second integrator connected in tandem with the first integrator. The first integrator provides an output signal corresponding to the integral of the difference between a first position signal indicative of the desired position of the drive shaft and a second position signal indicative of the actual position of the drive shaft. The second integrator responds to the output signal from the first integrator to provide a control signal. A control asrrangement responds to the control signal from the second integrator to accelerate the drive shaft. During acceleration of the drive shaft, the difference between the first and second position signals is driven to a value of zero.

Abstract: Disclosed is a disk drive servo system including a "switched-capacitor" digital filter means adapted to attenuate resonant vibration and enhance system stability and position loop control.

Abstract: In a position control system having force as a manipulated variable and position as a controlled variable, negative feedback of position and velocity is performed. Positive feedback of acceleration is performed through a first order lag circuit. Alternatively positive feedback of velocity is performed through a quasidifferential circuit. By the combination of negative and positive feedback, it is possible to stabilize vibration characteristics of the mechanism, which tends to make the control system stable, and to achieve position control with high gain, high response and high accuracy.

Abstract: A servo control apparatus comprising: a unit for generating a required position value; an actuator adapted to drive a load and having its maximum displacement in one direction and its minimum displacement in the other direction; a drive unit for driving the actuator; a position detecting unit for detecting a displacement of the actuator; and a control unit for correcting the required position value on basis of the maximum and minimum displacements of the actuator and for computing a deviation between an output of the position detecting unit and the corrected required position value; the load being controlled by the deviation.

Abstract: An apparatus for flicker protection when a servo motor driven sewing machine starts utilizing comparators. Setting the original voltage as the reference voltage and the dropped voltage as the monitor voltage, the comparator compares the voltages and, if the difference exceeded more than the predetermined value, signals for setting the maximum electric current to the servo motor are attenuated such that the voltage drop of the electric source will be reduced.

Abstract: The apparatus controls the positioning of a device in response to a commanded input signal, and comprises an element for moving the device in response to an error signal. A sensor component determines the actual position of the device, the sensor component outputting a primary signal and a derivative signal corresponding to the actual position and velocity of the device, respectively. A complementary filter system filters the primary signal and the derivative signal to generate a derived position signal, the derived position signal being combined with the commanded input signal thereby generating the error signal. The filtering results in effectively increasing the resolution of the sensor component thereby reducing the limit cycle caused by quantization of the sensor component.