Abstract: A method includes providing a rail, a first conveying unit movably mounted on the rail, and a central controller configured to control the first conveying unit; displacing the first conveying unit along the rail at a first speed; obtaining a first vibration measurement upon the displacement of the first conveying unit along the rail at the first speed; analyzing the first vibration measurement; transmitting a first signal based on the analysis of the first vibration measurement to the central controller; providing a second conveying unit movably mounted on the rail; transmitting a first feedback signal based on the first signal from the central controller to the second conveying unit; and displacing the second conveying unit along the rail at a second speed based on the first feedback signal.

Abstract: A stage apparatus includes: a coarse moving stage; a fine moving stage located at an interval from the coarse moving stage in a first direction; an electromagnetic actuator including a first core located on one of the coarse moving stage and the fine moving stage and a second core located on the other of the coarse moving stage and the fine moving stage and configured to accelerate or decelerate the fine moving stage in a second direction perpendicular to the first direction; and a controller configured to correct a command value of a thrust of the electromagnetic actuator in the second direction in accordance with a relative position of the fine moving stage with respect to the coarse moving stage in the first direction.

Abstract: The invention relates to a device, system and method of automated manufacture comprising: delivering a workpiece with a delivery device; receiving the workpiece with a receiving device, the delivering of the workpiece and the receiving of the workpiece being electronically synchronized; processing the workpiece with a processing tool while the workpiece is on the receiving device; transferring the workpiece to a completion device, the ejection of the workpiece and the transferring of the workpiece being electronically synchronized. In particular the workpiece may comprise: a platform with mounts supporting a first component in a selected orientation; and a locating surface, the method comprising: engaging and disengaging the locating surface of the workpiece with releasable connectors on the delivery device, on the receiving device and on the completion device.

Abstract: A removable cartridge for magnetic head and disk testers is disclosed. The removable cartridge includes: a base plate; a first end of an actuator rigidly fixed to the base plate; an HGA mounting block rigidly fixed to a second end of the actuator; a first end of a flexure rigidly coupled to the HGA mounting block; and a second end of the flexure rigidly coupled to the base plate.

Abstract: A common electrode plate formed on a common electrode base attached to the lower surface of the movable stage faces a split electrode plate formed on a split electrode base attached to the upper surface of a main base, which are apart from each other at a predetermined interval. A support mechanism formed of ball bearings, ball stoppers at the movable side, steel balls, ball stoppers at the fixed side, and ball bearings allows the movable stage to move in directions of the X-axis, Y-axis and turning. A linear actuator 19 is driven to move the movable stage in the directions of X-axis, Y-axis, and turning.

Abstract: An alignment apparatus which moves a object comprises a first structure having a holding member which holds the object, a second structure having a magnet which constitutes a linear motor, the linear motor drives the first and second structure, and a flow passage formed between the holding member and the magnet.

Abstract: An actuating system having an electric motor that is controlled by a computer as a function of a setpoint position of a member that is to be actuated. The actuating system includes an encoder that is dependent on the movement of the motor, a sensor designed to deliver two square digital position signals in quadrature and which are representative of the position of the encoder, a device for processing the signals and which can determine the actual position of the encoder, and a device for comparing the actual position of the encoder with the position of the encoder that corresponds, in theory, to the applied setpoint. The actuating system can be used to actuate a member and/or actuate a device that meters the amount of fuel provided to a heat engine.

Abstract: In a method for active compensation of mechanical vibrations and/or deformations in industrial processing machines, a main drive in a primary axis executes a first motion to move a mechanical machine element with an auxiliary drive in a secondary axis for execution of a second comparably more fine-tuned motion to move a machine point by the auxiliary drive in such a way that the movement of the machine point is composed of superimposed portions of the first and second motions. The first motion of the machine point moves hereby in accordance with a predetermined desired position value, and the second motion so compensates vibrations and/or deformation of the mechanical machine point that the machine point assumes the desired predetermined position.

Abstract: In a method for active compensation of mechanical vibrations and/or deformations in industrial processing machines, a main drive in a primary axis executes a first motion to move a mechanical machine element with an auxiliary drive in a secondary axis for execution of a second comparably more fine-tuned motion to move a machine point by the auxiliary drive in such a way that the movement of the machine point is composed of superimposed portions of the first and second motions. The first motion of the machine point moves hereby in accordance with a predetermined desired position value, and the second motion so compensates vibrations and/or deformation of the mechanical machine point that the machine point assumes the desired predetermined position.

Abstract: A storage disk apparatus has a storage disk having servo information, a plurality of heads for reading information recorded on the storage disk, a plurality of first actuators for accurately positioning the heads with respect to the storage disk, a second actuator for coarsely positioning the heads with respect to the storage disk, and a control circuit for controlling the first actuators and the second actuator according to the servo information read by one of the heads. The control circuit supplies a drive current value depending on the servo information read by one of the heads to one of the first actuators to position the one of the heads, and also supplies the drive current value to the other first actuators to position the other heads. When one of the heads is positionally detected, all the first actuators, typically microactuators, are prevented from being vibrated and relatively displaced from the second actuator in a seek mode.

Abstract: A pair of complementary magnetic actuators controls a stage in a high-precision positioning instrument in a single coordinate direction. Additional pairs of complementary magnetic actuators can be used to provide control of the stage in other coordinate directions. A small current through the windings of both magnetic actuators provides a zero net force on the fine stage, thus maintaining the position of the fine stage. The small current used to control the fine stage minimizes the RMS power gain. By increasing the current in one magnetic actuator while decreasing the current in the other, a net force is generated for large accelerations of the stage. Control of the magnetic actuators is simplified by simultaneously increasing and decreasing the current through the windings of the complementary magnetic actuators prior to accelerating the stage. Additionally, a feedforward command can control the magnetic actuators to decrease the settling time of the system.

Abstract: In a position control system, the positional deviation between the position of the control point of the controlled object and the target position is corrected in accordance with the change of the relative positional relationship between mechanically related control axes. The control axes include a main shaft stand and a main shaft. The main shaft stand is supported by a column so that it can move in a vertical direction and is driven by the rotation of a screw shaft. The main shaft is provided on the main shaft stand so that the main shaft stand can move in a horizontal direction. The positional deviation of the main shaft from the target position in the vertical direction is calculated in accordance with the horizontal position of the main shaft with respect to the main shaft stand at the time of the position control. The position of the main shaft from the target position in the vertical direction is corrected based on the positional deviation.

Abstract: A micropositioner has a coarse positioner and a fine positioner, with a separate closed loop control circuit for the fine positioner. A disk head being positioned over a disk is attached to the stage of the fine positioner. The fine positioner includes a parallelogram flexure having first and second opposite sides attached respectively to the coarse positioning stage and the fine positioning stage. A piezoelectric translator translates the second side of the flexure relative to the coarse positioning stage. In order to sense displacement of the fine positioning stage relative to the coarse positioning stage, a differential electric field sensor is employed. The sensor includes a pair of side plates both mounted fixedly relative to one of the stages and opposing each other to create an electrical field between them, and a probe plate mounted fixedly relative to the other of the two stages and between the two side plates.

Abstract: A precision positioning control apparatus includes a coarse positioner, a fine positioner, a displacement totalizer for totaling the displacements of the two positioners, a total displacement detector for producing a total displacement signal, a comparator for producing an error signal, a coarse positioner adjuster for adjusting the error signal and inputting the adjusted signal to the coarse positioner, and fine positioner adjuster for adjusting the error signal and inputting the adjusted signal to the fine positioner. The coarse position adjuster includes a gain element, a transfer element, a limitter, an integrator, a gain adjuster and an adder.

Abstract: A method of controlling a stage includes the steps of setting a plurality of drive modes according to which the stage is driven, which correspond to a plurality of positioning processes for positioning an element supported by the stage, and driving the stage according to the plurality of drive modes corresponding to the plurality of positioning processes. An exposure apparatus employing such a method includes a stage mechanism on which a substrate is placed, an exposure device for exposing the substrate to light, a memory for storing data representing a plurality of drive modes according to which the stage mechanism is driven for positioning the substrate, a driver for driving the stage mechanism in accordance with the drive modes, and a controller for selecting one of the drive modes stored in the memory in accordance with a positioning process according to which the substrate is to be positioned, and for controlling the driver in accordance with the selected drive mode.

Abstract: A positioning method and positioning system wherein a driving device, for moving a movable table on a rough-motion stage by a small amount, is alternately controlled through a pair of switchable control systems. The amounts by which the table is driven are initially adjusted to the same amounts by the pair of control systems when the paired control systems are switched.

Abstract: A numerically controlled lathe capable of machining a workpiece by numerically controlling a machining table provided with a machining tool. In order to prevent a local uneven abrasion of parts, which make a sliding contact, due to a mass production of workpieces having a simple form or a machining in a non-circular shape, there are provided a main carriage and a sub carriage. A machining tool is positioned on the sub carriage, and the sub carriage traverses on the main carriage along an axis which the main carriage and the sub carriage have in common. When a circular machining is carried out, the main carriage and the sub carriage respectively traverse by an equal amount in directions opposite to each other, and the cutting tool is constantly maintained at a position designated by an instruction.

Abstract: A device for the rapid precision positioning of a heavy carriage employs stationary positioning bar, for instance a part of a linear electric motor or a gear rack, and a cooperating moving part of the linear motor or a motor attached to the carriage. The carriage is rapidly and roughly displaced with a further drive which may be constituted by a further gear wheel that cooperates with a gear rack and is driven by a separate motor attached to the carriage. This further drive additionally delivers a certain force for the final positioning in such a way that the play between the gear wheel and the gear rack is eliminated by biasing. Instead of a second gear wheel together with its motor a toothed belt, also driven by a separate motor, a pneumatic cylinder or a linear motor may be used. These are mounted separately from the carriage and ar principally fixed in space.

Abstract: A positioning control method and apparatus in which a fine movement mechanism is moved without exceeding a movable area so that positioning of a large amount of displacement can be attained with high accuracy and high-speed positioning from a point to a point with the same control method. A coarse movement mechanism (101) has a large amount of movement and low positioning accuracy and a fine movement mechanism (102) on the coarse movement mechanism has a small amount of movement and high positioning accuracy.

Abstract: A positioning control for linearly displacing an object (31) has a direct current motor (1) and a gear (2,21) for converting rotary into linear motion, a current supply (4) of current pulses having given frequency, amplitude and duration; a pole reverser; a rotatable operating element (51) coupled to an angular step generator (5) and a sensor of the sense of rotation. The pulse frequency of the current supply (4) is determined by the angular step generator (5) and the polarity of the pole changer is determined by the sensor of the sense of rotation. The characteristic curve of the speed of displacement of the object (31) as a function of the pulse frequency is kinked, in that for low pulse frequencies the speed increases proportionally slowly, and up from the level of a pulse frequency threshold, the speed increases markedly quicker. The invention is useful for microscope focussing drives.

Abstract: In a rotary-disk transducer position control apparatus and method in which positional information concerning a transducer relative to a rotary disk based on a signal is obtained from the transducer which is disposed in opposition to the rotary disk, a seek instruction is inputted through an input device so that a first transducer access mechanism is caused to make the transducer perform a seeking operation at a low speed with a large stroke in accordance with both the positional information and the seek instruction, and in order to make the transducer perform both a seeking operation and a following operation, a second transducer access mechanism is caused to drive the transducer at a high speed with a small stroke in accordance with the positional information and the seek instruction.

Abstract: A gravity axis brake control method of controlling the brake of the gravity axis of a computerized numerical controlled machine tool, wherein a computerized numerical control (CNC) notifies a programmable controller (PC) that the control of the gravity axis will be interrupted (Step S1), the PC outputs a signal for actuating the brake at the machine tool (step S3), and the CNC turns off an exciting current of a servo motor after a preset brake operation completion time has passed (step S7). The preset time is longer than the time after that at which the CNC notifies the PC to interrupt the control of the servo motor as compared to the time at which the brake locks the gravity axis.

Abstract: A technique for overcoming the difficulties that arise from the transition between coarse and fine loop control. Coarse and fine phase locked loops, each having a respective latch provide a coarse number in the range 000.0.degree.-359.9.degree. and a fine number in the range of 0.0000.degree.-0.9999.degree.. The coarse number is offset relative to the fine number so that the least significant digit (tenths digit) of the coarse number is always less than the most significant digit (tenths digit) of the fine number over the entire range of motion. The fine number latch is clocked by a reference clock (ZDS) while correlation circuitry provides a clock signal for the coarse number latch. The correlation circuitry generates the clock signal when the tenths digit of the coarse number agrees with the latched fine number. The result is a latched fine number and a coarse number that is latched when it correlates with the fine number (tenths digits agree).

Abstract: A system for carrying out reference point return in a numerical control device is provided, including a deceleration dog having a short length and arranged at a machine table, a deceleration limit switch operated by the deceleration dog, for generating a deceleration start signal, and a time setting device (6) for setting a deceleration time, starting with a generation of the deceleration start signal and ending with a generation of a deceleration end signal, and a slow-speed travel time. A reference point return processing device (5) starts a deceleration of the machine table in response to the deceleration start signal, and stops the machine table at a first electrical grid point reached by the machine table after the slow-speed travel time has elapsed after the passing of the deceleration time.

Abstract: A computer winding control and operator display for winding complex coils is programmed to control stepper motors connected to an arbor and a coil filament laying head. The computer program generates a series of commands to move the arbor and the head. The commands specify acceleration, velocity, extent of movement, and deceleration. The program at certain program steps stops the motion and generates operator display messages.

Abstract: A rotary element (10) such as a robot arm is to be positioned by an actuating drive to a position determined by a desired value signal. An angle pick-off (20) provides an actual value signal. A first controller (36) provides a first controller output signal through an adaptive transfer element with limitation. The first controller output signal is applied to a first torque motor (18) the rotor of which is directly connected with the rotary element (10). A second controller (38) provides a second controller output signal, which is applied to a second torque motor (22). The second torque motor (22) is connected with the rotary element (10) through a step down system (26) and a resilient coupling member (30). A coupling path (40) with an integrator applies a trimming signal dependent on the input of the first torque motor (18) to the input of the second torque motor (22).

Abstract: As disclosed herein, a new and improved method and apparatus provide for fine tuning the position of a servomotor used to drive a transducer mounted on an ultrasound probe to a desired position. This improvement is accomplished by processing the analog quadrature output signals of an incremental optical encoder, coupled to the servomotor. The improvement uses the positional information derived from the analog quadrature output signals. The analog quadrature output signals, defined as sine and cosine, are converted to digital square waves. The digital square waves are decoded to produce digital position quadrants, wherein each quadrant represents a specific motor position. The corresponding digital square waves are also decoded by a logic array device and coupled to the select input of an analog switch.

Abstract: In an apparatus for measuring texture and characterization of the surface of a sample on the basis of the drive signal of a servo control circuit by allowing a probe-tip (1) to approach the sample (2) and subjecting the probe-tip (1) to servo control so that a current, which is generated by moving the probe-tip (1) on the sample surface and which flows between the probe-tip (1) and the sample (2), becomes constant, the present invention discloses a surface metrological apparatus comprising a circuit (11, 12) for correcting the texture and characterization of the sample by use of a current error of the measured value of the current described above from the set current value.

Abstract: A technique for overcoming the difficulties that arise from the transition between coarse and fine loop control. Coarse and fine phase locked loops, each having a respective latch, provide a coarse number in the range 000.0.degree.-359.9.degree. and a fine number in the range of 0.0000.degree.-0.9999.degree.. The coarse number is offset relative to the fine number so that the least significant digit (tenths digit) of the coarse number is always less than the most significant digit (tenths digit) of the fine number over the entire range of motion. The fine number latch is clocked by a reference clock (ZDS) while correlation circuitry provides a clock signal for the coarse number latch. The correlation circuitry generates the clock signal when the tenths digit of the coarse number agrees with the latched fine number. The result is a latched fine number and a coarse number that is latched when it correlates with the fine number (tenths digits agree).

Abstract: A first servo system (31) which feeds back at least position and speed and a second servo system (32) which effects integral control by feeding back position are connected in series. A first signal obtained by multiplying the output of the integral controller of the second servo system by a first gain is added to the position feedback signal of the first servo system, while a second signal obtained by multiplying the input of the integral controller of the second servo system by a second gain is added to the speed feedback signal of the first servo system. In this way, feedback control is effected using one mutual position detector, thereby eliminating the dynamic interference between the first and second servo systems, and thus enabling the two servo systems to be activated simultaneously.

Abstract: A motion converter is disposed at the input to a work station to convert the constant velocity of sheet material as it is payed out from a roll into a cyclic, stop and go motion. The motion converter includes a pair of actuators containing electromagnets and these are alternately energized to attract the sheet material first against a contoured surface and then a flat surface. Sheet material accumulates in a serpentine path within the motion converter when attracted toward the contoured surface and it is expelled rapidly therefrom when attracted toward the flat surface. A programmed position control operates the electromagnets in response to position feedback signals from sensors on the motion converter.

Abstract: In a numerical control system for a machine tool using a general-purpose motor (11) in place of at least one of servo motors, a current position of a spindle (10) driven by the general-purpose motor (11) is detected (14, 9) and is compared with a position designated by a numerical control program. When the current position approaches the position designated by the numerical control program, brake signals (MBR, BR) are generated to brake the general-purpose motor (11) or the like, and a rotation signal (MCW, MCCW) of the general-purpose motor (11) is disabled, thereby stopping the general-purpose motor (11) so as to cause the spindle (10) to stop at the position designated by the numerical control program.

Abstract: A method of accessing a rotary recording medium for positioning a head at a desired track on the rotary recording medium by using a coarse actuator and a fine actuator, comprising the steps of comparing an output signal produced from a detector for detecting movement of the fine actuator occurring immediately before initiation of an access operation of the coarse actuator with an output signal subsequently produced from the detector during the access operation of the coarse actuator to produce a comparison output signal, and locking the fine actuator at a state occurring immediately before the initiation of the access operation by driving the fine actuator on the basis of the comparison output signal to thereby suppress vibrations of the fine actuator due to translocations of the coarse actuator. An information memory apparatus utilizing the access method is also disclosed.

Abstract: A system for positioning a movable body for a processing machine. A lead screw is rotatably and axially shiftably supported and engaged with the movable body. The lead screw is rotated by a motor to move the movable body. A hydrostatic thrust bearing is provided for preventing axial movement of the lead screw. The lead screw is finely moved in the axial direction by controlling the pressure difference of oil supplied to the thrust bearing to position the movable body.

Abstract: A two-part head positioning system has a tracking motor for moving the head through relatively small distances so that it follows the track of a medium and moves between adjacent tracks and a seek motor for moving the tracking motor and head through relatively large distances between non-adjacent tracks. The system has been improved by mechanically isolating the seek motor from the tracking motor so that small movements from the tracking motor are not transmitted to or from the seek motor and the arm between that motor and the tracking motor. The tracking motor and the mechanical isolator are in one unit. A magnet is mounted on the head support, which extends from the tracking motor to the head. This magnet is positioned within an electromagnetic coil that is mounted within magnetic shielding and fixed to the arm extending to the seek motor. Selective energization of the electromagnetic coil moves the magnet and the head support laterally in the coil.

Abstract: A precision machining system for machining a workpiece into a desired surface with two tool driving units. A first drive unit moves the tool along at least two axes to shape the workpiece similar to a desired surface. A second drive unit moves the tool along one of the axes in a very finely controlled manner. A measuring unit measures the tool position with an accuracy higher than that to which the first drive unit can respond. A signal producing unit is responsive to the measuring unit for producing a control signal for controlling the operation of the second drive unit while the first drive unit is operating.

Abstract: A system for finely feeding a movable member being movable relative to a stationary member.This fine feed system is constructed such that the movable member is provided with a fine feed mechanism, which includes a screwshaft and a nut member threadably coupled to the screwshaft and capable of being suitably clamped against the stationary member. A control device is provided for causing a driving motor to drive the screwshaft on condition that a detector to regulate the relatively movable range between the screwshaft and the nut member is not in operation, while, for causing the driving motor to operate so that the screwshaft and the nut member can return to original relative positions, on condition that the nut member is not clamped against the stationary member. The fine feed of the movable member can be instantaneously performed no matter where the movable member may be in its movable range.

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

Abstract: A data track searching device capable of switching between two modes; one being the rough searching mode in which a transducer is displaced at a high velocity to a desired track and the other being the fine searching mode which follows the rough searching mode and in which the transducer is displaced at a relative low velocity and positioned over the proper or desired track. The operating point of a tracking element is shifted or deviated as a result of the high-velocity displacement of the transducer in the rough searching mode so that stable searching cannot be ensured. According to the present invention, therefore, the acceleration of the transducer in the rough searching mode is detected and a signal representative of the thus detected acceleration is applied to the tracking element so that the shift or deviation of the operating point of the tracking element can substantially made nil.

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

Abstract: Positioning device for a printer comprising a type carrier daisy wheel fitted on a carriage movable in front of the platen. The selection of type and movement of carriage are carried out by selection and transport motors of direct current type which are controlled by velocity servo motors through corresponding digital transducer and position counters. After a coarse positioning by the servo motor, the exact final position is reached and kept by exciting a couple of magnetic positioners whose rotor is keyed on the axes of the selection and transport motors.Economic solutions are also described to synchronize, during initialization of the machine, the content of the position counters with the effective positions of the daisy wheel and carriage.

Abstract: A welding machine includes a programming device to move a welding head relative to horizontal main X and Y axes, and to rotate the head about a vertical C axis. A sensor is connected to rotate with the welding head on a rotator. A sine cosine resolver is mounted on the rotator so that its shaft is geared to the rotator gear. Deviations from the programmed path which may occur in the weld groove are sensed by the sensor, which in turn causes the resolver output to drive a slide mechanism which defines deviation axes X.sub.d and Y.sub.d and which causes the weld head to move from its programmed path to the desired corrected path, when needed. The overriding correction is independent of the program.

Abstract: A welding machine includes a programming device to move a welding head relative to horizontal main X and Y axes, and to rotate the head about a vertical C axis. A sensor is connected to rotate with the welding head on a rotator. A sine cosine resolver is mounted on the rotator so that its shaft is geared to the rotator gear. Deviations from the programmed path which may occur in the weld groove are sensed by the sensor, which in turn causes the resolver output to drive a slide mechanism which defines deviation axes X.sub.d and Y.sub.d and which causes the weld head to move from its programmed path to the desired corrected path, when needed. The resolver includes a deviation correction control rotor winding and a second rotor winding, the latter selectively impressing signals on the X.sub.d and/or Y.sub.d slide mechanism drive to cause the welding head to effectively change speed independent of the program or of the existence of any deviation.

Abstract: A sequentially operated machine employs two positionable members, a movable center selection piston member and a movable transducer member for accessing a record storage member selected by the central piston member. Making the record storage member available to the transducer reuires a predetermined time delay. Accordingly, the servomechanism powering the selecting mechanism has a high response, while a following servomechanism transporting the transducer has a low response such that cost is reduced while not adversely affecting access time to the record member.

Abstract: A speed control device for a moving member which comprises a moving member, driving mechanism for the moving member, position coherent light containing a position information of the moving member, reference coherent light so formed as to not containing the position information of the moving member for required formation of the position coherent light and an interference light, interference light forming means utilizing the position coherent light and the reference coherent light, means for detecting interference light formed by the interference light forming means, and controlling means for the driving means to render the detected output obtained by the detection means to become a sinusoidal wave having a predetermined frequency.

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

Abstract: A machine drive system includes two motors which are to be driven with a selected velocity ratio. To one of these motors a coarse control is applied, and which the velocity ratio approximates the desired value, a fine control is applied to the other motor. The system may be hydraulic or electric. The hydraulic version employs a single pump to drive the two motors, and the fine control is conveniently a valve in a fluid line bypass around the associated motor. An error signal obtained from a comparison of the two speeds is used to govern the coarse/fine control.

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

Abstract: A positioning stage assembly having a coarse stage which includes a planar motor driveable in at least two degrees of freedom, and a fine stage positioned on the coarse stage which is driveable in at least three degrees of freedom with respect to the coarse stage. More preferably, the fine stage is driveable in six degrees of freedom and includes variable reluctance actuators for positioning in three degrees of freedom.