Abstract: An exposure apparatus which exposes a substrate to a pattern. The apparatus includes a channel which causes pure water to flow as a coolant, a temperature adjustment unit which adjusts a temperature of the coolant flowing in the channel, and a UV sterilization unit which performs UV sterilization processing for the coolant flowing in the channel.

Abstract: A device is for braking a magnetic levitation railway, wherein the stator winding of a linear motor is short-circuited as a brake winding in a last section before an end of the route. There is a provision for two stator windings which extend alternately on the stator to be present in a penultimate section.

Abstract: An anti-vibration apparatus includes a first magnet unit arranged on a support target and including a first permanent magnet, and a second magnet unit including a pair of second permanent magnets. The pair of second permanent magnets is arranged to interpose the first permanent magnet without contact such that the same magnetic poles of the first and second permanent magnets oppose each other. Sizes of the first and second magnet units are set such that a force acting between the first and second magnet units in a direction perpendicular to a direction in which the first magnet unit supports the support target is zero in a relative positional range between the first and second magnet units.

Abstract: The drive method consists in setting in vibration a moving mass of a vibrating device for a portable object using a series of voltage pulses provided to the coil of the vibrating device, which is electro-magnetically coupled to the moving mass. In a phase of driving the oscillations of the moving mass after a start phase of the vibrating device, followed by a resonant frequency measurement phase, successive rectangular voltage pulses of alternating polarity are provided to the coil by a drive circuit. The width of the successive pulses is modulated in a substantially similar manner during each successive oscillation period which allows a substantially sinusoidal voltage wave (SF) of determined amplitude to be defined whose fundamental frequency is adapted to the resonant frequency of the moving mass. By modifying the oscillation period, it is thus possible to act on the amplitude of the moving mass oscillations which depends on the sinusoidal wave amplitude defined by the rectangular pulse width modulation.

Abstract: In a linear motor and its progressive motion or motion control, e.g., for modular transport devices with straight and curved route sections forming a route course, extensive modularity or flexibility of the linear motor may be guaranteed with little expenditure in terms of equipment and software, e.g., with regard to various applications or machine configurations, e.g., when a plurality of secondary parts are used. A secondary part may have at least one permanent magnet and a signal processing device with a progressive motion or motion controller, which generates at least one set value relevant to the coil control. A set value is fed as a magnitude for commutation using a set value interface of a coil control that is stationary relative to the primary part. Device(s) are also provided for rigidly positioning the secondary part, the device(s) guiding the secondary part along a predetermined stretch.

Abstract: A stage system and a control method therefor. In one aspect, the stage system includes a stage which is going to be positioned, a magnetic material member provided on the stage, electromagnets disposed at opposite sides of the magnetic material member, a detector for detecting an electrical current value of a coil, which is a component of the electromagnets, and a position detector for detecting a position of the stage. The center position of the magnetic material member between the electromagnets can be determined on the basis of a relation between the position of the stage and the electrical current value of the coil, as the magnetic material member is moved relative to the electromagnets.

Abstract: A transporter is provided for moving a substrate and a patterning device relative to one another in a lithographic apparatus. The transporter includes a beam, a driver, and a slide. The slide is supported by the beam, and the driver is disposed to move the slide relative to the beam in a transport direction. The beam has a concave interior surface transverse to the transport direction, and the slide is supported against the concave interior surface in at least two directions transverse to the transport direction.

Abstract: The present invention provides a cylinder-type linear motor. The motor includes a fixed part including a coil assembly having a plurality of ring-shaped coils arranged in the axial direction to form a cylindrical space, and a yoke member made of a magnetic material, which is provided on the outer periphery side of the coil assembly and a moving part including a linear motion shaft provided on the axis line of the fixed part so as to be capable of reciprocating in the axial direction, and a permanent magnet assembly having one or more permanent magnets magnetized in the axial direction, which is provided on the linear motion shaft. The motor is characterized by when the axial length of the ring-shaped coil is taken as C, the axial length of the permanent magnet assembly as M, and the outside diameter thereof as D, a stroke S is equal to or smaller than (n×C?M), the axial length Y of the yoke member is set equal to or larger than (M+S+0.

Abstract: A controller for an electric machine, in particular for a linear motor, is disclosed. The electric machine or linear motor includes a first machine section with windings and a second machine section with permanent magnets. The controller includes a memory which can store one or more physical parameters, such as magnetic field parameters, that can be used to control the electric machine. The physical parameter(s) can be determined by having the electric machine perform one or more reference passes.

Abstract: A apparatus processes an object (19), such as a semi-conductor wafer at accurately controlled positions. The object (19) is supported by a working platform (12) that is moveable along a path. A suspension actuator part (14) attached to the working platform (12), contains a soft magnetic core (24) with poles facing the surface of a soft magnetic element (34) on the support structure along the path and a winding (20) for application of a current to generate a magnetic field that runs through the core (24) v the poles and returns via the soft magnetic element (34). A sensor (17) senses a measured position of the suspension actuator part (14) relative to the position reference element (16). A control circuit comprises an outer control circuit (40) and an inner control circuit (42). The outer control circuit (40) receives a sensing result and determines force set point information to regulate the measured position of the actuator part (14) to a required value.

Abstract: A device for adjusting the armature stroke in a reversible linear drive unit comprising an excitation coil and an armature displaceable in the magnetic field of the excitation coil according to a linear oscillating motion at a predefined armature stroke. The device comprising systems for detecting the current armature position, systems for measuring the actual excitation coil current and systems for adjusting the excitation coil current in such a way that the armature is exactly supplied with electric energy for obtaining the aptitude of oscillations of the armature stroke during each half-wave of the armature motion.

Abstract: A linear motor system that can extend the stroke of a linear motor, with power saving and at a low cost, is provided. In a linear motor system, constituted by a linear motor 100, a controller 7 for supplying a variable voltage, a winding switching device 6, for opening and closing phase windings 5 of individual phases that form a plurality of winding groups 4 that are separated in a stroke direction, the winding switching device 6 is constituted by a three-phase rectifying member, a semiconductor switch, which is located at both ends on the direct-current output side of the three-phase rectifying member, and a resistor and a capacitor, connected in parallel to the semiconductor switch. For each of the phase windings, which form the plurality of winding groups 4, separated in the stroke direction, one end is connected to the output end of the controller 7 and the other end is connected to an alternating-current input side of the three-phase rectifying member of the winding switching device 6.

Abstract: Current sensing resistors are connected directly to output terminals of MOSFETs forming the series switching stage of a PWM sinewave dimmer. An analog sensed current signal is coupled through an EMI resistant current link to comparators that provide an overcurrent indication in response to an overcurrent condition. A logic circuit overrides PWM control signals from a programmable controller, and operates drivers to render the series switching stage nonconductive and to render a clamp switching stage conductive until after the end of the current PWM duty cycle power on segment. The logic circuit sends an overcurrent signal through an optocoupler to an input of the programmable controller. The input of the controller is polled at a clock frequency for overcurrent signals and if the count exceeds a limit in any half cycle, or a maximum sum in sixteen half cycles of the AC supply, the series switching stage is rendered nonconductive and the clamp switching stage is rendered conductive pending a reset signal.

Abstract: A position feedback device for a linear motor utilizes Hall sensors which are properly positioned to induct the magnetic field variation of a linear motor and processing the inducted information with the OP amplifiers and signal level regulators to output Sine and Cosine differential signals.

Abstract: A magnetic levitation wafer stage is used to align a wafer in an exposure apparatus of photolithographic equipment. The wafer stage includes a base, a table supported on the base and whose entire top surface exhibits magnetism of a single polarity, and motors for moving the table in the X and Y directions relative to the base. Alternatively, the wafer stage includes a wafer table having a main body and a number of electromagnets disposed in an upper portion of the main body, and electronics that selectively supply current in either direction through coils of the electromagnets respectively and independently of one another. In the exposure process, the bottom surface of the substrate is provided with a magnetic substance such that the substrate exhibits magnetism of a given polarity. The substrate is delivered to and set on the table of the stage. There, the substrate is levitated by a magnetic force of repulsion between the substrate and the table.

Abstract: The invention relates to a method and an arrangement for operating a magnetically levitated vehicle by means of an arrangement having at least one long-stator linear motor. The linear motors are sub-divided longitudinally of a track into individual motor regions (A3, A4) in which only one vehicle (7e, 7f) at a time can normally travel. To increase the vehicle concentration along the track, provision is made in accordance with the invention for selected motor regions (A4) to be divided into at least two mutually independent motor region sections (A4a, A4b) and for one vehicle (7f, 7g) to be operated in each motor region section (A4a, A4b) at a part of that power which is preset for each motor region (A4).

Abstract: An apparatus for controlling an operation of a reciprocating compressor includes a voltage detecting unit for detecting a positive half-wave voltage of an AC voltage applied to a motor of the reciprocating compressor; a current detecting unit for detecting a positive half-wave current of the AC current passing through the motor; a voltage and current estimating unit for estimating a negative half-wave voltage of the AC voltage applied to the motor and a negative half-wave current of the AC current passing through the motor based on the detected positive half-wave voltage and the detected positive half-wave current; a stroke estimating unit for estimating a stroke of the reciprocating compressor based on the detected positive half-wave voltage and the detected positive half-wave current and the negative half-wave voltage and the negative half-wave current which have been estimated by the voltage and the current estimating unit; a stroke controller for outputting a stroke control signal of the reciprocating com

Abstract: A method of actuating a movable object in a first degree of freedom includes a) providing a first motor assembly including one or more motors of a first type and a second motor assembly including one or more motors of a second type, each of the first and second motor assembles being configured to move the movable object in the first degree of freedom, b) feeding the first motor assembly with a feed-forward signal of a feed-forward unit on the basis of a feed-forward reference signal, and c) feeding the second motor assembly with a control signal of a position control unit on the basis of a position control reference signal.

Abstract: A system and method are disclosed for controlling an integrated rotary-linear actuator system that may be coupled to a network via a network interface. The integrated rotary-linear actuator system includes a control system and a rotary-linear actuator having a moveable plunger and associated coils. The coils may be energized to interact with associated magnets to effect corresponding movement of the plunger, which may include rotation and/or linear movement. The network interface facilitates receipt of control information at the control system of the integrated rotary-linear actuator system from the network. The control system may control an amplifier to energize the coils based on the control information.

Abstract: A multi-phase motor drive includes coil magnets that generate a magnetic field when energized with an electrical current. The coil magnets are configured in an electrical matrix. Switches are arranged in an electrical circuit with the coil magnets. Each coil magnet is in electrical communication with at least two of the switches and each switch is in electrical communication with more than one coil magnet. The switches operate in pairs to energize the coil magnets and the multi-phase motor drive includes a lesser number of switch pairs than coil magnets.

Abstract: A method and an apparatus for estimating the position of a moving part of a linear actuator are provided. The method comprises the following steps. Move the moving part towards a target position. Receive magnetic signals generated by the magneto-resistive sensor of the linear actuator, which include a sine signal and a cosine signal. Then, generate a first square wave, a second square wave, and a regional square wave based on the sine signal and the cosine signal. Generate a saw-tooth wave based on the sine signal, the cosine signal, the second square wave, and the regional square wave. Next, calculate the number of regions which the moving part is across from the origin point based on the first square wave, the second square wave, and the regional square wave. Finally, estimate the current position of the moving part based on the saw-tooth wave and the number of regions.

Abstract: A system is disclosed that controls the power flow to Linear Synchronous Motor (LSM) stators for a vehicle transport system. This invention allows multiple vehicles to operate in close proximity in a guideway without requiring an excessive number of separate controllers. It can be used in conjunction with schemes now in use and is particularly useful in elevator hoistways or for automated people movers near stations.

Abstract: A system implementing a controller for linear motors is disclosed having a plurality of switches, a reorganization switch control detecting available hot spot sensors, encoder failures, and current sensor failures, and a storage storing a decision matrix having controller reorganization conditions. Upon detecting available hot spot sensors, encoder failures and recoveries, and current sensor failures and recoveries, the reorganization switch control reorganizes itself via configuring at least one of the switches based on information in said decision matrix to operate without available sensors and using available sensors.

Abstract: The present invention relates to an alternating current electrical motor having a first element with magnets of alternating polarities, and a second element with electrical conductor coils, the first and the second elements being mounted for relative motion to one another. A controller for the electrical motor comprising: a current source for energizing the coils with an alternating current to produce a movement of the first and the second elements relative to one another; a sensor for sensing a phase shift between the magnets and the current in the coils; and a current source controller for varying an amplitude of the current to substantially regulate the phase shift to an optimum phase shift value, thereby providing a minimum power consumption for proper operation of the electrical motor.

Abstract: A developing apparatus is capable of moving a stage for supporting a substance to be developed from a detachable position to a developing area below a developing unit, and two-dimensional movement. The present developing apparatus includes a developing device, a first moving device movable in a direction of axis of ordinate and a second moving device movable in a direction of axis of abscissa, and a stage posture control device to control an inclined posture of the stage in order to hold a relative distance between the developing device and a developing area surface of the substance placed on the stage constant.

Abstract: A sensorless method of detecting piston collisions in a reciprocating free piston linear compressor driven by an electronically commutated linear motor having at least one excitation winding is provided. A free piston gas compressor is also provided.

Abstract: A driving controlling apparatus for a linear compressor, comprises: a storing unit for storing a reference phase difference to judge an overload state; and a controlling unit for judging an overload state based on a comparison result between the reference phase difference and a phase difference between a current and a stroke, and controlling a voltage or a current applied to a linear motor based on the judgement result.

Abstract: A driving controlling apparatus for a linear compressor, comprises a controlling unit for detecting a TDC by a phase difference inflection point between a stoke and a current with increasing the stroke by controlling the current applied to a linear motor, and for varying the current applied to the linear motor based on the detected TDC.

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: A moving control apparatus comprising: a moving member provided movably at least in one direction; a driver having a movable element connected to the moving member and a stator to displace the movable element; a controller which energizes the driver to cause the movable element to generate a thrust; a position detector which detects a relative position between the movable element and the stator in the driver; a measurement unit which drives the movable element of the driver and measures an induced voltage generated in the driver; and a correction calculator which calculates a thrust ripple correction value to correct a thrust ripple as a variation of a thrust generated in the driver from the measured induced voltage and the relative position in the driver, and multiplies a command to the driver by the correction value.

Abstract: The present invention discloses an apparatus for controlling an operation of a reciprocating compressor and a method therefor which can reduce errors in an operation of a stroke estimated value of the reciprocating compressor, by previously preventing over-saturation of a magnetic flux density generated in a coil of a motor. The apparatus for controlling the operation of the reciprocating compressor includes a magnetic flux saturation constant operation unit for operating a magnetic flux saturation constant of a motor of the reciprocating compressor on the basis of a stroke estimated value of the reciprocating compressor, a stroke reference value generation unit for generating an increased or decreased stroke reference value by increasing or decreasing a predetermined stroke reference value on the basis of the magnetic flux saturation constant, and a control unit for controlling a voltage applied to the motor of the reciprocating compressor on the basis of the generated stroke reference value.

Abstract: The invention provides a device for improving the positioning accuracy of a linear motor. A stator 20 is designed to have two kinds of magnets with different surface magnetism arranged alternately and at uniform intervals along the linear moving direction. A moving member 30 is disposed movably in the linear direction while maintaining a uniform distance from the stator. A detector head 50 formed integrally with the moving member 30 detects the magnetic flux of the stator 20 and sends the data to a control unit 60. The fixed laser length measuring machine 100 irradiates a laser beam LB to a target 110 attached to the moving member, and using the reflected light, measures the distance between the laser length measuring machine and the target highly accurately.

Abstract: A linear power controller and related circuitry may be implemented to provide linear control of a variable DC electric motor. The controller and motor are coupled to form a closed loop for controlling the speed of the motor and for adjusting or compensating for noise and other characteristics having a negative impact on performance. The circuitry is configured to have a crossover frequency that is below the motor noise frequency. The configuration of the crossover frequency may allow for the motor or the controller to be implemented without additional circuitry to filter or compensate for motor noise.

Abstract: The present invention relates to a linear traversing carriage for use in the papermaking industry and the like, which incorporates an air gap inductive motivator and eliminates all mechanical devices between the electrical power supply and the traversing mechanism. Specifically, the present invention relates to a linear traversing device comprising an inductor type linear motor comprising an electrical stator winding, a conductive platen extending over an entire traverse length of the device, a ferromagnetic material affixed to said conductive platen, a support means for supporting the device and maintaining an air-gap between the stator winding and the conductive platen, a user selected feed forward velocity map for driving the device, a controller that controls a movement of the device according to the user selected feed forward velocity map.

Abstract: Methods and apparatus for precise positioning of an object using linear actuators based on linear stepper motors operating in microstepping or full step mode, a control algorithm based on compensation table, and a calibration apparatus for obtaining the compensation table.

Abstract: An elevator, particularly for transporting passengers, has an elevator car guided in an elevator shaft a direct drive motor. The drive motor includes an active primary part at the elevator car and a passive secondary part that is fixed in the elevator shaft and is spaced from the primary part by an air gap. In order to achieve a high power capability, the drive motor is configured as a transverse flux motor that moves the primary part linearly relative to the secondary part under the influence of an electromagnetic propulsive force. The secondary part has at least one rail made of a soft magnetic material and subdivided into a plurality of segments having a predetermined length. The segments are fixed to a wall of the elevator shaft by intermediate elements.

Abstract: A linear motor having a more preferable braking function is realized with a low cost. A linear motor has a slider and a stator. A driving winding is wound around the slider. A plurality of permanent magnets forming magnetic poles which invert at a predetermined period are provided on a surface of the slider opposing the stator. Teeth are formed on the stator with a predetermined spacing therebetween. The stator extends to a region outside of an effective movable range, and a braking winding is wound around the teeth in the extended portion. When the slider moves into a region outside of the effective movable range, an induced voltage is generated in the braking winding and a current flows. A thrust in a direction opposite to the movement direction of the slider is generated by the current.

Abstract: A linear drive apparatus comprising: a guide having an internal body; a slider moved along the guide, a driving mechanism for generating a driving force by magnetic interaction of the slider with the guide so as to linearly drive the slider; and a magnetic measurement unit having a magnetic scale and a detector which are opposed to each other and change a relative position relative to each other in order to obtain the relative position of the slider relative to the guide, wherein an opposing direction of the magnetic scale and the detector is the direction of the outer circumference of the guide, and the detector detects a signal from the magnetic scale in accordance with the relative position of the slider, whereby the relative position of the slider is obtained.

Abstract: An electromagnetic transducer which may be driven as a linear electric motor (which may be a permanent magnet motor or a variable reluctance motor) in which coils disposed around first and second cores are positioned on opposite sides of a longitudinal plane in which the longitudinal axis of the armature lies. The transducer may be arranged to work as a generator.

Abstract: An alignment stage apparatus including a vacuum chamber, a linear motor including a plurality of coils to drive a stage, a coil selector which selectively energizes the plurality of coils, and a storage box arranged to store the coil selector. The interior of the storage box is connected to the outside of the vacuum chamber. The linear motor and the storage box are arranged in the vacuum chamber.

Abstract: A turn-on interlock for propelling a vehicle, in particular a magnetic levitation train (maglev), along a track is disclosed, as well as a drive incorporating the turn-on interlock. A stator of a linear motor forming the drive and extending along the track is divided into a plurality of stator sections which can be sequentially connected to an electric power source for propelling the vehicle. Each stator section has one or more feed switches for connecting the stator section to an electric power source, and signaling elements ganged with the feed switches. The turn-on interlock prevents more than one stator section from being connected to the power source at any given time. A stator section can only be connected if all signaling elements or all signaling elements of at least a predetermined subset of the signaling elements indicate an “open” switching state of the feed switch.

Abstract: The invention provides for the monitoring and control of a system, such as a linear electro-mechanical transducer, e.g. a linear electric motor, particularly when driven in a reciprocating manner. A dynamic model of the linear motor and its load is used to calculate from the input drive to the motor a predicted response of the motor. The predicted response is compared to a measured response and the model parameters are varied by global optimisation until the two match as closely as desired. The drive may be the voltage input to the electrical motor and the response may be the electrical current in the motor coils. The parameters and variables of the model, after optimisation, can be taken as good estimates of the actual operating parameters and variables of the linear motor. This gives a measurement of such quantities as the stoke and offset of the linear motor. The invention is particularly applicable to the use of linear motors to drive compressors, for instance in Stirling cycle coolers.

Abstract: The invention relates to a method and to a circuit arrangement used to regulate synchronous linear motors, especially linear drive mechanisms in film drawing systems. The force (Fclip) between the stationary primary part and the moved secondary part is determined in a sensorless manner from the voltages and currents calculated and measured in a frequency converter in a functional block, in such a manner that the integral is calculated from the active power during a time period (tclip) between two pulses (new—clip) produced by an overriding control and said integral is divided by the active length (1zone) of the primary part. Alternatively, the force (Fclip) can also be determined by summation of the voltages in the f-axis in order to reduce the drop in voltage in relation to the resistance (Rstr) of the branch in the primary part. Voltages and currents are transformed on the primary part by a co-ordinate system related to the secondary part.

Abstract: An apparatus for effecting non-contact linear door displacement comprising a tubular motor formed of a stator (1) formed from a plurality of magnets (21) arranged along a linear axis (15), and at least one thrust block (3) each formed of at least one electrically conductive coil encircling the stator (1) at a distance sufficient to facilitate electro-mechanical interaction between the plurality of coils and the stator (1), at least one door (5) attached to at least one of the plurality of thrust blocks (3) via a hanger (9) and the at least one door (5) capable of a movement in the direction of the linear axis (15), a rolling component (11) to enable movement of the hanger (9) in the direction of the linear axis (15), and a control mechanism (70) for sensing the position of each of the at least one door (5) and issuing an electrical control signal to each of the plurality of thrust blocks (3) so as to affect the movement of the at least one door (5).

Abstract: An alignment stage apparatus includes a base structure and a movable stage which can move along a surface of the base structure so as not to be in contact with the base structure. The apparatus includes a plurality of power transmission coils buried under the surface of the base structure, a power reception coil attached to the movable stage to oppose the surface, a switching device for sequentially switching, of the plurality of power transmission coils, those that are to be energized to feed power in accordance with a position of the movable stage, and a power feeding device for supplying AC power to the power transmission coils to be energized through the switching device.

Abstract: A mover device and an ion implanter apparatus having a processing base that reciprocates at a high speed without undesirable noise and vibration are provided. The mover device includes: a fixed base; a movable base that is linearly movable with respect to the fixed base; a processing base that is linearly movable with respect to the movable base; a main linear motor that generates a moving force to move the processing base with respect to the movable base, thereby moving the processing base with respect to the fixed base; and a velocity control unit that controls the moving velocity of the processing base with respect to the fixed base. In this mover device, the movable base is moved by virtue of a reaction force caused by the moving force to move the processing base.

Abstract: A method of controlling an oscillating electric motor of a small electric appliance, the method including supplying an electric current to a coil to produce a magnetic field emanating from a first motor component and setting a second motor component in an oscillatory motion relative to the first motor component; determining at least one electrical characteristic of the coil for an instant of time at which current is supplied to the coil, the at least one electrical characteristic being related to a motion quantity of the first motor component relative to the second motor component; and then supplying further current to the coil as a function of the at least one electrical characteristic determined.

Abstract: The invention relates to an arrangement for operating a magnetically levitated vehicle by means of an arrangement having at least one long-stator linear motor. The linear motors are sub-divided, longitudinally of a track, into individual motor regions (A) in each of which only one vehicle (7) is able to travel at a time. To make possible different frequencies of service for the vehicles (7), i.e. different intervals between the vehicles (7), the region boundaries (B) between at least two motor regions (A1, A2) which follow one another in the direction of travel are arranged to be variable.

Abstract: A kind of 2-D variable reluctance planar motor comprises: a stator base combined by a plurality of laminated steel bricks; a moving platform consisting of two rows of spaced coil-shoes; traditional sliding supports to hold said platform above said stator base; two electronic rulers for scaling the real position of the platform; traditional supporting means for holding the platform at a distance above the stator base; computer and software for generating motion command signal to PWM generator; PWM current generator for energizing the coils of the moving platform; when a reference data (the final position of the platform) is input into the computer, the computer will give command to the platform and make it moving; once the moving platform is set in motion, the electronic rules continuously detect and transfer the location data of said platform to the computer; the computer continuously compares the data sent by said rules with reference data and gives command to the platform until said two kinds of data are eq

Abstract: The modular conveyor system comprises N interconnected track sections, forming a continuous track, wherein each track section features a plurality of individually controlled coils stretching along the length thereof. Plural pallets, each having thrust producing magnets, travel independently alone the track. The track also comprises multiple linear encoder readers spaced at fixed positions therealong, and each pallet includes a linear encoder strip having a length R greater than the spacing E between the readers. Track section controllers associate the encoder strips with only one reader at any time in order to resolve the position of the pallets based on the fixed position of the readers and the relative positions of the strips in relation thereto. The section controllers also regulate and commutate the coils of the corresponding track sections in order to independently control each pallet. Communication links interface adjacent section controllers situated in adjacent track sections.