Abstract: A method of controlling a DC motor is presented. In a tracking action, an input to the motor is tracked. In a comparing action, the input is compared against a baseline value. In an adjusting action, a usage of the motor is adjusted when the input passes a threshold related to a motor performance parameter. A method of estimating a parameter of an ink carriage moved by a DC motor is also presented. In a tracking step, an input to the motor is tracked. In a comparing action, the input is compared against a baseline value to predict a level of the parameter.

Abstract: Resting position error recognition for an ink-jet, translational-type, service station mechanism. Service station drive mechanism binding due to hard stop impact is compensated for by calculating a difference between when the drive mechanism stops and when a predetermined velocity change was first recorded. In a more sophisticated embodiment, noise filtering is employed to improve accuracy with increasing number of uses of the service station mechanism.

Abstract: The present invention is a motor controller. An encoder manipulates the motor controller in a manner that is new and novel. The encoder tracks movement of a material along an assembly line and reports the results of the tracking through electronic signals. Those electronic signals are used to manipulate the motor controller to produce unique and responsive control signals to manipulate the motors, particularly during the acceleration and deceleration of the motors. Other motor control systems have used encoders as a part of a feedback loop, but none allow encoders to exert the level of control over the motors as accomplished in the present invention.

Abstract: A method for correctly connecting the wiring for the hall effect sensors and the motor phase terminals of a three-phase brushless DC motor to the corresponding connections on an amplifier, the method using known waveforms that describe the electrical operational characteristics of the motor and amplifier. The method comprising connecting the hall effect sensors in any order, determining two motor phase terminals that correspond to a back-electro-magnetic-force peak in the middle of a waveform for a first hall effect sensor and a third motor phase terminal that does not, determining an amplifier pin that does not carry current during the middle of a wave form for a first hall sensor input on the amplifier. The correct connection is thus determined to be between the third motor phase terminal and the identified amplifier pin. The remaining connections are determined in the same manner by repeating this process, but in relation to the other hall effect sensor waveforms.

Abstract: A machine tool and a control method therefor providing an improved machining accuracy even when a numerical control and electronic cam control coexist. The CPU determines the moving position of the workpiece, the tool, and the drilling tool according to the command from each channel machining sequence storage portion, and outputs the determined position as a command signal in response to the pulse signal generated at the pulse signal generating circuit. The workpiece, the tool, and the drilling tool are thereby electronic cam controlled. The CPU also determines the moving position of the workpiece and the tool according to the command from each channel machining sequence storage portion, and outputs the determined position as a command signal in response to the divided timing signal generated at the divided timing signal generating circuit. The workpiece and the tool are thereby numerically controlled.

Abstract: A motor speed control having synchronous PWM signals has a synchronous phase detecting unit and a PWM control unit. The synchronous phase detecting unit detects the phase variation of a Hall signal, which represents the phase change of the motor, and outputs a digital value to the PWM control unit. The PWM control unit compares the digital value with a speed control command so as to obtain a PWM signal, wherein the PWM signal is synchronized with the Hall signal. Since the PWM signal is synchronized with the Hall signal, the motor is operated smoothly even in the low speed rotation, and audible noises are effectively reduced.

Abstract: A controlling method and apparatus for positioning a robot that can output an optimal speed instruction for controlling residual vibration after completion of a moving operation, achieve reduction in tact time for the moving operation, and shorten the length of setting time. The method is a controlling method for positioning a robot (1) for performing a point-to-point moving operation comprising: performing a test operation to measure a frequency of a residual vibration that is stopped at a target position; measuring a magnitude of the residual vibration based on the frequency during each of different lengths of moving time for a predetermined moving distance to find a relationship between the length of moving time and the magnitude of the vibration; calculating a shortest moving time at which vibration magnitude is minimized; and performing the point-to-point operation for the calculated shortest moving time, thereby to position the robot (1) at the target position.

Abstract: The invention makes it possible to execute the pre-control and the fine interpolation in the drive (A) in the fast drive clock (tDR) with a slower path pre-setting in the clock (tNC) of the NC. For this purpose, in each NC clock (tNC) a setpoint speed value (nNC*) and the P gain (kP) of the NC position controller (L_NC) and the desired axle speed (nNC) and the average axle speed (nNCMW) during the last NC position controller clock are transferred from the NC to the drive. From this information, polynomial segments of the third degree are in each case generated on the drive side, valid for the duration of an NC position controller clock (tNC). They are constructed in such a way that the speed at the polynomial transitions is constant. A variable component of the position polynomial is determined as the fine position component xF, with which the setpoint position values are finely interpolated in the drive.

Abstract: The present invention provides a numerical control apparatus for a machine tool, which corrects an axial displacement of a main spindle caused due to a change in preload level and occurring according to the rotation speed of the main spindle. The numerical control apparatus (3) comprises: a numerical control section (6) for numerically controlling the movement of a spindle head (2) and for outputting a rotation command; a spindle control section (7) for controlling the rotation of a main spindle (5); a preload change control section (8) for changing the level of a preload applied to bearings (36, 37); and a correcting section (9) for outputting correction data for correction of an axial displacement of the main spindle (5) caused due to a change in the preload level and occurring according to the rotation speed of the main spindle (5) to the numerical control section (6) on the basis of the rotation command.

Abstract: An apparatus for setting control parameters of a machining apparatus. The setting apparatus includes a storage unit for storing a set of control parameters for each of a plurality of machining modes; an input device for selecting one of the plurality of machining modes; and a control unit for selecting a set of control parameters corresponding the selected machining mode and setting the set of control parameters as control parameters to be used for controlling the machining apparatus.

Abstract: The present invention relates to a method of controlling a numerically controlled machine tool having a plurality of feed shafts. Also, the present invention relates to a numerically controlled machine tool. According to the present invention, it is possible to solve conventional problems so as to realize highly accurate machining even when a moving body of the machine is moved at high speed. As the means for solving the problems, an appropriate command corresponding to a frictional force of the feed mechanism of the numerically controlled machine tool and also corresponding to a change in the weight of a workpiece is estimated by calculation, and the thus estimated command is outputted into the drive unit of the feed shaft motor so as to drive the feed shaft motor.

Abstract: In a controller where a contour machining is performed through a synchronous control between a mechanically movable portion (servo axis) driven by a servo motor and a main shaft (spindle axis) driven by a spindle motor, the position of the servo axis and the position of the spindle axis are collected at the same timing for each predetermined cycle and are stored. The position data of the servo axis and the spindle axis stored are converted to obtain a machining contour shape data, and the shape obtained is displayed on a display device of a personal computer or the like.

Abstract: Where high control precision is required in contour control or the like, mode B for a short PWM period is selected to assure a high control precision. Where high torque is required in fast feed, high acceleration or deceleration, mode A for long PWM period is selected so as to decrease the rate of the time of dead zone &dgr; where voltage is not applied to the motor.

Abstract: A motor rotational pulse generating circuit for a motor is provided which generates a correct pulse signal even at an initial turning-on stage of the motor, by adjusting a filter cutoff frequency in response to motor rotational condition. The motor rotational pulse generating circuit includes a rotational pulse generation circuit 20 which generates ripple pulses based on a signal being inputted from the DC motor 1, in which a ripple is superposed whose frequency is in proportion to a rotation number of the DC motor 1. A filter 3 makes a cutoff frequency variable on the basis of a clock signal issued from a PLL circuit 6. An oscillation frequency at an oscillator VCO10 is determined by the ripple pulses and a motor rotation condition signal inputted by way of circuits 12 to 16 inclusive. A microcomputer 20 operates, when the motor is turned on, to cause the oscillator VCO10 to issue a preliminary clock signal.

Abstract: A system having an electric machine, memory device for storing information concerning the electric machine and is attached to the electric machine, and at least one control unit for controlling the operation of the electric machine. Furthermore, the system of the present invention has an interface between the memory device and the at least one control unit so that the at least one control unit reads the information stored in the memory device. The control unit processes the information read from the memory device such that the information becomes verified with default parameters of the system after read-out-thereof. In case the information includes parameters, which do not match in a predefined manner with the default parameters, the control unit is arranged to either automatically, adjust the system in accordance with the information received from the memory device or to prevent start-up of the electric machine or the entire system.

Abstract: A printer belt drive control circuit comprises: an encoder count circuit (4) for counting output signals from a drive encoder (11) attached to a drive motor (10) and from a motor encoder attached to a belt motor (6), a servo controller which under control of a CPU (1) and outputs a rotation speed information of the belt motor (6) according to tan output signal from the encoder count circuit (4), and a motor drive signal generation circuit for converting an output information from the servo controller (2) into a form appropriate for an H-bridge driver circuit (5) which directly drives the belt motor (6)

Abstract: A digital signal processor for closed loop velocity or position control receives sine winding output signals and cosine winding output signal from a resolver, digitizes the signals and outputs quadrature encoded signals to an excitation circuit. The excitation circuit is connected to an excitation winding in the resolver to provide signals for driving the resolver.

Abstract: An oscillation isolator for supporting an oscillation isolation platform on a pedestal includes an active oscillation isolator having a displacement generating type actuator to reduce oscillation of the platform and a displacement adjuster provided between the active oscillation isolator and the platform or the pedestal for adjusting relative displacement between the active oscillation isolator and the platform or the pedestal. The displacement adjuster has a rigidity higher than that of the active oscillation isolator and is dynamically located in series between the active oscillation isolator and the platform or the pedestal.

Abstract: An electronic detent apparatus and method for simulating a mechanical detent comprises a sensor connected to a microprocessor. A servo-motor is connected to the microprocessor and has a motor drive connected to a clutch. The clutch may engage a wheel disposed upon a rail or surface to effect the simulation of a mechanical detent through the microprocessor controlled servo-motor. The method for simulating a mechanical detent comprises the steps of moving an axis and monitoring the position and velocity of the axis. The position and velocity of the axis is then compared to a pre-specified position threshold value and a pre-specified velocity threshold value using a microprocessor disposed on the axis. A servo-motor is activated to accelerate the axis to a pre-specified position using a clutch controlled by the servo-motor when the position and velocity of the axis exceed the pre-specified position and velocity threshold values.

Abstract: An data interface module is provided for allowing a user to remotely modify a predetermined number of operating parameters of a motor driven by a motor control and for displaying the same. The interface module includes a micro-controller interconnected to a communications network and a visual display structure. The visual display structure has a first screen which displays a scrollable list of the operating parameters and a second screen which displays a data value for a user selected one of the operating parameters. A user may modify the user selected operating parameter when the second screen is displayed.

Abstract: A multi-purpose controller for variables which closely controls such variables to set point by making sequential corrections to the level of input to the system of the variable based on: system response time, relationship of controller output to the variable, deviation of the variable from set point, and change in system load as determined by change in error and change in system input. The controller has a self tuning capability and can provide generation of the set point according to a set of variable parameters. It can be configured as a stand alone controller, as an intelligent Input/Output device for another intelligent device, or be resident in another intelligent device such as a programmable controller, computer or other microprocessor based device.

Abstract: A control method for an NC machine tool is provided which ensures a high precision of the contouring control, and allows for extension of the drill life, and reduction in machining time.

Abstract: Electric-component mounting system for mounting an electric component on a substrate, including a movable portion movable relative to a main body, a motion-transmitting member disposed on the main body and operable to transmit to the movable portion a linear motion generated by a drive device, such that thermal expansion of the motion-transmitting member causes a positioning error of the movable portion, an object fixedly disposed on one of the main body and the movable portion, an image-taking device fixedly disposed on the other of the main body and the movable portion to take an image of the object, the object and the image-taking device being positioned relative to each other such that an error of relative positioning therebetween detected on the basis of the image of the object substantially represents a positioning error of the object due to thermal expansion of the system, and a controller operable to determine a drive signal to operate drive device, on the basis of the image of the object, so as to re

Abstract: A speed control device particularly adapted for use with electrical motor-driven hand tools has digital operator input controls. A semiconductor switching device controls a percentage of ON time for the electric motor in the hand tool. Discrete and repeatable settings are selectable to a user through digital input switches.

Abstract: A motor control apparatus and a method according to the invention are directed to detecting a motor velocity. Leading and trailing edges of two pulse signals are distinctively detected from one another, and those pulse signals have cycles which are proportional to the motor velocity, and a phase difference between the pulse signals is about one quarter of a single cycle from one another. Then, a period of time between the pulse edges in the same direction of the same pulse signal is measured, and the period of time between the pulse edges is used to sequentially convert it into the motor velocity and thereby detect the motor velocity.

Abstract: In a numerical control apparatus 1, a synchronous control management unit 11 manages the dominant relation of plural axes to be controlled synchronously. In case of the position control system, in the axis control unit which controls the reference axis, a synchronous position calculation processing unit 74 calculates the command position to the reference axis. On the other hand, in the axis control unit which control the synchronous axis, the synchronous position calculation processing unit 74 calculates the moving stroke per unit time of the synchronous axis, thereby calculating the command position to the synchronous axis. One axis control unit which controls the reference axis and plural axis control units for controlling the synchronous axes issue the calculated command positions, and control the individual corresponding motors, and therefore control plural axes synchronously to one reference axis, and further control other axis synchronously by reference to the corresponding synchronous axis.

Abstract: A numerical control apparatus for the numerical control of a roll grinding machine comprises a flaw detecting means for scanning the entire surface of a roll (11), provided with an ultrasonic detecting head (23) for detecting flaws formed in the surface of the roll (11), a command generating means for generating cross-feed commands to repair detected flaws on the basis of flaw information about the positions and levels of the detected flaws, a control means for executing a first shaft position control operation on the basis of the cross-feed command to position the grinding wheel at a position with respect to a Z-axis corresponding to the position of the flaw by moving the wheel spindle stock in parallel to the axis of the roll and a second shaft positioning control operation to cross-feed the grinding wheel in parallel to an X-axis, and a decision means for deciding whether or not the flaw has been completely repaired and invoking the next cross-feed command if the flaw has been completely repaired.

Abstract: A scanner motor acceleration method that uses a software driver and a flexible process method to enable a scanner to perform fast scanning operation without increasing motor cost or complex hardware design. Motor acceleration and deceleration may be done through software control on existing scanner hardware which do not support acceleration and deceleration function. Through positioning and speeding mechanisms of existing scanner hardware, and software which may be changed flexibly, scanner positioning function may be accurately performed without deviations.

Abstract: An improved servo system for galvanometers, scanners and similar devices which uses digital processing to increase the dynamic range and provide greater effective resolution. The system provides digital control of a reference point that directly influences the excitation, which in turn directly influences the gain of the circuit. A high and low resolution switching path is provided to optimize dynamic range. Wide angle torque compensation improves uniformity of response at large angular deflections from zero. Improved thermal protection allows safe operation near system thermal limits. A graphical user interface allows adjustments and changes response on the fly for tuning due to input conditions or user control.

Abstract: A position encoder and a method for estimating absolute position using two or more diffractive grating tracks of differing periods to generate interference fringe patterns on a multi-track sensor. Detectors, corresponding to the diffractive grating tracks, detect the interference fringes. A first processing circuitry coupled to the detectors extract phase signals from the signals from the detectors. A second processing circuitry then estimates the cycle counts of the track signals based on the phase signals from the first processing circuitry. The absolute position is estimated by combining the cycle count, the fractional fringe value, and the grating period.

Abstract: Disclosed is a system for an operating-cycle synchronized disengagement and re-engagement of groups of servo axles to be synchronized electronically and a method for disengaging and engaging a servo axle group to be synchronized electronically with a master position value sequence where, by correlations of master position value sequences stored in a computer, and servo axle group reference values assigned to these sequences in each case, the servo axle group reference values are determined in such a way that, following engagement, synchronization of the speed and angle of the servo axle group with the master position value sequence is carried out.

Abstract: In a handle feeding control method in a numerical control apparatus in which a control axis can be controlled in response to a pulse signal output from a manual pulse generator for generating the pulse signal according to the turning quantity of a manual handle so as to perform handle feeding, at least one of a movement quantity, a target position and a movement range of the control axis is set and stored; and the movement quantity or position of the control axis at the time of the handle feeding is monitored, and pulse signals from the manual pulse generator thereafter when the movement quantity or position of the control axis at the time of the handle feeding reaches the limit of the set and stored movement quantity, target position or movement range are, invalidated so that the movement quantity or position of the control axis at the time of the handle feeding is prevented from exceeding the set and stored movement quantity, target position or movement range.

Abstract: In a numerical control apparatus 1, a synchronous control management unit 11 manages the dominant relation of plural axes to be controlled synchronously. In case of the position control system (synchronous control of axes), in the axis control unit which controls the reference axis, a synchronous position calculation processing unit 74 calculates the command position to the reference axis, by adding the moving stroke of the reference axis calculated in an axis control command value converting unit 72 to the reference position of the reference axis.

Abstract: Disclosed herein are a motor control circuits and a control system comprising the motor control circuits.

Abstract: A positional control system wherein the position of the controlled object connected to a drive means is controlled to a variable target or desired position. A period is determined which starts with a detection of a reversal in the direction of the feed of a positional command Pr as well as the detection of a stoppage of a table 104 as a controlled object and which ends with a detection of the re-start of the movement of the table 104. During the period, a correction amount for correcting a positional deviation E is issued.

Abstract: A controller using rectified AC voltage to drive a DC motor. A first rectified produces a waveform that passes through zero voltage in synchronization with the A.C. supply voltage. The first rectified voltage is applied to the D.C. motor. A second rectified voltage produces a waveform that passes through zero voltage in synchronization with the A.C. supply voltage. A circuit generating a unipolar waveform output voltage drives a switch that turns on and off the connection of the first rectified voltage to the D.C. motor. The on time can vary from zero to one half of the period of the AC voltage for maximum speed. The switching is synchronized with the unipolar waveform. The time on is varied by varying the pulse width driving the switching device.

Abstract: A numeric control device of a turning mechanism which turns a turning body from a driving source which circularly moves through a non-linear transmitting mechanism has a coordinate transformation device outputting a signal which converts an inputted turning angular signal into a position of the driving source, and a compensator outputting a signal which is derived from computing a positional error of the driving source in accordance with the turning angular signal, and the control of the driving source is carried out by a servo-input signal which is derived from the sum of a conversion signal outputted from the coordinate transformation device and a compensation signal outputted from the compensator. Since the numerical control mechanism of the present invention controls the driving source with addition of the compensation signal, it becomes possible to stabilize the turning velocity of the turning body with high accuracy.

Abstract: This invention relates to a control device for a motor output (DM) comprising electrical control and protection switchgear (CD) for a motor (M) receiving contact information (a1, a2, a3) connected to the electrical switchgear (CD) and its output controlling at least one control device (KM) that controls starting or stopping the motor (M) and also receiving information from a remote sensor (C) and communicating with a “master” network controller (PLC) through a communication bus (B), characterized by the fact that the electronics (E) comprises means of locally controlling the control device (KM) stopping the motor (M) as soon as the remote sensor (C) is activated during an operating phase of the motor output and means of sending information corresponding to this stop on the bus (B) to the “master” module (PLC).

Abstract: The method for detecting after-running of electrical servomotors with incremental position detection, particularly for servomotors in motor vehicles, includes detecting position signals of position indicators and storing the detected states of the position signals or the states of the position indicators after switching off the motor in a nonvolatile memory. The evaluation electronics can be intermittently disconnected from the supply voltage. They are provided with a buffer that is large enough for position detection and storage after disconnection of the evaluation electronics from the supply voltage. The nonvolatile memory can be an EEPROM in the microcontroller of the evaluation electronics.

Abstract: A rotary encoder includes a disk-shaped scale and sensors, each including a light emitting part and a light detecting part, for outputting an electrical signal. A light beam is emitted from the light emitting part so as to illuminate the scale with the emitted light beam and a light beam reflected from the scale is incident on the light detecting part, thereby generating an electrical signal corresponding to the amount of light incident upon the light detecting part.

Abstract: An object of the present invention is realizing a highly accurate synchronous control device which does not cause time lag by detecting the rotational frequency and phase simultaneously perpetually by same signal in the synchronous control of plural electric motors. The synchronous control device synchronizes accurately rotational frequency and rotation phase of an electric motor or a machine axis driven by the electric motor. A master section outputs phase signals or frequency signals based on rotational frequency reference.

Abstract: Device for digitally slaving the position of a moving part, including: a digital sensor (20) which is intended to measure the actual position of the moving part (10) and delivers a digital effective position value, drive means comprising an electric motor (30) for driving the moving part into a setpoint position defined by a digital setpoint value, a digital control unit (50) delivering at least one signal for controlling a circuit (40) for supplying the motor as a function of the discrepancy between the said setpoint value and the said actual value, in which the digital sensor having a determined measuring interval, the motor supply circuit comprises timer means for maintaining the supply to the motor for the time which is necessary and sufficient for the sensor to be positioned at the middle of the interval corresponding to the setpoint value.

Abstract: Tool feed speed Fa (mm/min) is calculated for each tool feed step on the basis of a tool feed speed F (mm/rev) specified in advance and the actual rotational speed Sact of the spindle (rev/min). The tool feed speed Fa (mm/min) and the tool feed speed Fold of the previous cycle (initially, a value based on the maximum rotational speed S of the spindle as a tentative feed speed Fold) are compared, and if a change has been detected, a tool feed speed Fb (mm/min) for the subsequent tool feed step is calculated based on the relation between the tool feed speed Fc (mm/min) based on the subsequent maximum rotational speed S of the spindle (rev/min), the maximum rotational speed S of the spindle (rev/min), and the rotational speed Sact of the spindle (rev/min); and the tool feed speed undergoes pre-interpolation acceleration/deceleration control on the basis of the subsequent tool feed speed Fb (mm/min) and the tool feed speed Fa (mm/min).

Abstract: A control system in accordance with the invention comprises error signal generating means for generating an error signal in response to a reference signal and a first and a second position signal. The reference signal is a measure of the desired value of a position of a first part of a drive system with respect to a second part of the drive system. The position signals are a measure of the actual value of said position. The error signal is a measure of the difference between the desired value and the actual value of the position. The control system further comprises energizing means for energizing a motor which is to be controlled by the control system in dependence on the error signal. The control system of the invention is characterized in that the error signal generating means are adapted to generate weighting factors from the reference signal, for weighting the position signals with the weighting factors and determining a sum of the weighted position signals.

Abstract: A method and apparatus for smoothing a throttle plate position command prior to being used by a closed loop throttle control unit. The method sequentially indexes through a lookup table storing a series of values of a smoothing function at routine time intervals. The difference between the current throttle plate command and the received throttle plate command is multiplied by the value of the smoothing function indexed from the lookup table. The product is then added to a reference throttle plate position command to generate a series of smoothed throttle plate position commands applied to the throttle control unit which provides smoother operation.

Abstract: A numeric array of move command data Qi constituting a reference cam diagram F (.theta.) is stored in advance in a data table of a CMOS memory. Alternatively, a shift position of a cam corresponding to a rotational angle .theta. of the cam is stored in advance so that move command data can be generated by obtaining the shift position of the cam from the rotational angle of the cam based on the rotational angle value. In response to the input of a shift Ka in the lift direction, shift Kb in the pitch-circle direction, maximum lift Kc, and data number n as a criterion for extension or compression in the pitch-circle direction, the move command data can be corrected by automatic processing by means of a motion controller. Thus, final move command data Pk can be generated and outputted as position commands.

Abstract: A controller for an electric motor, includes a reference circuit and control circuitry. The reference circuit generates a reference signal having a phase and frequency determined in accordance with a set of motion parameters input to the circuit. The control circuitry receives the reference signal and receives a feedback signal from a rotation detector coupled to the motor, the detector having a predetermined rotational resolution, and compares the reference signal and the feedback signal to generate a drive signal used to drive the motor at a speed and phase of rotation determined by the frequency and phase of the reference signal. The phase of rotation of the motor is locked to the phase of the reference signal such that deviation of the phase of rotation relative to the phase of the reference signal at steady state is substantially smaller than the rotational resolution of the rotation detector.

Abstract: A circuit arrangement for powering an electric motor having at least three windings from a direct voltage source via a commutation circuit which, for each winding terminal of the electric motor, comprises a commutation branch including a first and a second switching element by which the relevant winding terminals can be connected selectively to a first terminal of the direct voltage source or, via a measurement impedance, to a second terminal of the direct voltage source. A ring counter device periodically changes over the switching elements of the commutation circuit in accordance with a signal series which is cycled through the ring counter device under control of a clock signal, one period of the ring counter device corresponding to one complete cycle of the signal series through the ring counter device. A clock frequency generating stage supplies the clock signal whose clock frequency is dependent on the measurement voltage.

Abstract: A motion controller and a method of controlling the motion of a plurality of axes which prevents a discontinuous position command being generated to a follower axis. A follower mode transfer function circuit or routine generates a position command in response to a master axis position. This function can be in the form of electronic gearing or camming. A bias latch is utilized to offset any change in position resulting from a change in mode, such as changing from electronic gearing to electronic camming, changing cam profiles or gearing ratios, or changing the master axis. The latch is summed with the transfer function position command and a standard move command profile generator position command to provide the follower axis position command. The latch is recalculated each time the follower mode is changed.

Abstract: An amount of difference between a commanded position and an actual position resulting from reversing a direction of movement is found before machining and is stored in a memory of a positional difference controller (9). Then, a move command Pc is monitored in the process of machining as to whether or not a sign of the move command is reversed, and the amount of difference is added to the move command to correct a move command value when the reversion of the sign is detected. Then, position/speed/current control (3) is performed on the basis of a difference between the corrected move command value and position feedback Pf from a servo motor (5), that is, a corrected positional deviation Er, and the servo motor (5) is driven.