Abstract: A linear motor path forms a closed figure. Contactless power control and position feedback permit a linear motor stage to traverse the closed figure without interference from trailing wires. One embodiment of the closed figure includes a racetrack pattern with straight runs joined by curved ends. Axes of armature windings are skewed to lie across the path in the curved ends to maintain force on the linear motor stage. Other embodiments of the invention includes multilevel paths wherein one portion of the path crosses over another portion of the path. Disclosure is made of a linear motor stage supported below the path by magnetic attraction between permanent magnets on the stage and magnetic material in the path.

Abstract: An actuator, with two independent degrees of freedom, rotates a stage about an axis and moves the stage along the axis, the range of motion defining a cylinder or cylindrical section. The stage is mounted on a hollow cylindrical plunger fitting in an annular well. A bearing allows the plunger to move axially and rotationally, in the preferred embodiment the bearing is an air bearing. The plunger has an array of permanent magnets on its external cylindrical face opposite coils in the well. Equal numbers of oppositely-polarized permanent magnets are arranged in a regular cylindrical pattern at 50% packing density forming rings and columns of like-polarity magnets, the rings of one polarity alternating with rings of opposite polarity and the columns of one polarity alternating with columns of opposite polarity. A set of Z-axis coils (for axial movement) curve around the plunger and are shaped to allow a current in them to produce an axial force with respect to the rings of magnets. A set of .phi.

Abstract: A linear motor having motor magnets on a movable stage, also includes non-interleaved armature windings on a path. The magnets are arranged m along the span A of the movable stage. The armature windings are arranged with n windings occupying a distance equal to the span S. A switching device automatically switches power on to the armature windings entering the span, and switches power off to the windings leaving the span. The switching is done when the a magnet is aligned with the coil whose power is being switched on or off in order to minimizes switching noise. Switching is conveniently done using Hall effect devices controlling the switches, and a switching magnet, movable with the stage, having a length equal to the span. As the switching magnet comes within magnetic interaction distance of a Hall effect device, the Hall effect device closes its associated switch.

Abstract: A motor controller produces independent first and second drive power signals for independent application to first and second linear motor stages movable on the same path. Each armature winding in the path is connected to a first switch receiving the first drive power and to a second switch receiving the second drive power. A first switch control device associated with the first linear motor stage actuates the first switches in its vicinity, while leaving the remaining first switches unactuated. A second switch control device associated with the second linear motor stage actuates the second switches in its vicinity, while leaving the remaining second switches unactuated. Each linear motor stage has an encoder associated with it to inform the motor controller of its position and/or motion.

Abstract: A linear motor having motor magnets on a movable stage, also includes non-interleaved armature windings on a path. The magnets are arranged m along the span A of the movable stage. The armature windings are arranged with n windings occupying a distance equal to the span S. A switching device automatically switches power on to the armature windings entering the span, and switches power off to the windings leaving the span. The switching is done when the a magnet is aligned with the coil whose power is being switched on or off in order to minimizes switching noise. Switching is conveniently done using Hall effect devices controlling the switches, and a switching magnet, movable with the stage, having a length equal to the span. As the switching magnet comes within magnetic interaction distance of a Hall effect device, the Hall effect device closes its associated switch.

Abstract: A linear motor employs motor permanent magnets in a movable stage interacting with armature windings in a path of the movable stage. Drive power to each individual armature winding is through a magnetically controlled switch. A switching magnet affixed to and moving with the stage actuates only those magnetically controlled switches that control power to armature windings that are within a magnetic influence of the motor permanent magnets. All other armature windings remain cut off. An encoder magnet, having alternating magnetic polarities, is affixed to and moving with the stage. The encoder magnet passes within a magnetic influence of a stationary encoder sensor which applies a stage position signal to a motor controller. The combination of motor permanent magnets, switching magnet and encoder magnet provides a wireless system that does not require active elements on the stage.

Abstract: A path module for a linear motor, for use with a linear motor stage, includes switching sensors and encoder sensors. The switching sensors energize only those armature windings that are within the magnetic influence of the linear motor stage. The stage carries an encoder magnet having magnetic zones of alternating polarity. The encoder magnet has a length D. An encoder sensor in one path module is separated from its nearest counterpart in an adjacent path module by no more than the distance D. In the preferred embodiment, each path module has three encoder sensors spaced D/2 apart, and the outer ones of the three encoder sensors are spaced D/4 from their mating ends, whereby, when adjacent path modules are assembled, closest encoder sensors in adjacent modules are spaced D/2 apart.

Abstract: A linear encoder system includes an encoder magnet having alternating magnetic zones. The end ones of the magnetic zones are tapered. A distance between the centers of the tapered magnetic zones defines a span. First and second encoder sensors, sensitive to the alternating magnetic zones, are spaced apart a distance equal to the span. As the encoder magnet moves into alignment with one tapered magnetic zone, and out of alignment with the other magnetic zone, the decrease in signal from one magnetic zone is approximately equal to the increase in signal from the other magnetic zone. In one embodiment of the invention, a third encoder sensor is positioned midway between the first and second encoder sensors.

Abstract: A linear motor has an epoxy core armature with dual cold plates attached to a top and a bottom of the epoxy core armature to effect cooling of the epoxy core armature. The use of dual cold plates with circulating cooling fluid reduces heat build up by providing paths of high thermal conductivity from any point in the epoxy core armature to the cold plates. Another embodiment of the invention employs ceramic heat sink plates laminated to sides of the epoxy core armature to increase the thermal conductivity and the resultant power dissipation capacity of the epoxy core armature without introducing magnetic or electrically conducting materials. Other embodiments of the invention utilize cold plates formed from extrusions of aluminum or ceramic materials. Still other embodiments have forced air cooling wherein a U-frame of the linear motor has longitudinal flexible seals and air is forced through the U-frame in which the epoxy core armature travel.

Abstract: An X-Y positioning machine has a forcer, with armature coils, that moves around on a platen, supported by an air bearing. Magnets embedded in the motor platen generate a fixed magnetic field with which the armature coils interact. Perpendicular elongated coils interact with the fields of magnets in columns and rows. When a traditional rectangular pattern of the magnets is provided, a packing density and average peak magnetic flux intercepted by the coils are limited to 50%. The present invention provides magnet configurations that provide greater than 50% maximum peak flux density and up to 100% packing density. Several magnet arrangements are provided: a first in which round magnets are used instead of square, and a second in which diamond-shaped magnets are used. The latter can be used at 100% packing density arrangement. In addition to high peak flux density for a narrow coil, these embodiments exhibit low cogging forces. A method of making the magnet is also provided.

Abstract: A flat linear motor has a single row of permanent magnets mounted upon backplate and an armature having non-overlapping flat coils encapsulated in a block of epoxy resin mounted upon an armature backplate comprised of a magnetic material and having anchoring recesses or protrusions. The armature backplate serves to provide magnetic circuits of low magnetic resistance in the flat linear motor thereby increasing a force generated by the linear motor. A length of the armature backplate is a non-integral number of a pitch length of the permanent magnets so as to reduce cogging. The three non-overlapping flat coils are comprised of square wire windings which provide increased thermal conduction. An embodiment of the invention employs software commutation wherein a position sensing device is used by a controller to determine a position of the armature from which a field polarity is found by means of a formula or a look-up table.

Abstract: A linear motor has coil assemblies driven by multiple phases mounted side by side on a base plate such that they do not overlap. The coil assemblies include conductors wound upon teeth such that voids in the coil assemblies are minimized along with path lengths and thermal resistances between windings and the base plate, thus maximizing heat dissipation and the power capacity of the motor. The linear motor may have coil assemblies with teeth composed of a first material having desirable magnetic properties and a base plate composed of an inexpensive second material minimizing costs of materials. The teeth may be of varying lengths in or to further minimize voids. The coil assemblies are compactly mounted with a longitudinal axis normal to an axis of movement. Permanent magnets are mounted upon a back iron plate with axis of symmetry normal to the axis of movement.

Abstract: A tie gun for tying elongated bundles with a polymeric material tape loop, the loop having overlapped tape lengths, the overlapped material being welded with an ultra sonic horn, this horn embodying a horn tip end which with a clamp, and an anvil arrangement holds the loop in such way that a tape stock section just upstream of the weldment is weakened by horn operation disrupting at least some of the molecular orientation in the material so that the stock can be separated from the loop with an upstream directed pulling force applied to the tape stock resulting in a severance that leaves no objectionable protuberance or tab at the weldment. The tie gun also includes a quick release for freeing a tape build up in the gun incident a tape feed jam. A face of the clamp, face surfaces of the anvils and the horn tip end define a funnel envelope to facilitate tape stock feed to tape loop forming jaws on the gun at the outset of a tying cycle.

Abstract: A positioning device has a shuttle slidably and rotatably supported above a base assembly. A first linear motor moves the shuttle linearly in a first direction while the second and third linear motors move the shuttle linearly in a second direction, normal to the first direction. The second and third linear motors are separated along an axis in the first direction. The linear motors have magnetic arrays including rows of magnets or a checkerboard array of magnets and provide continuously variable positioning. Rotary movement of the shuttle is achieved by operating the second and third linear motors in opposing directions or at differing rates. The positions of three points on the shuttle are determined by three optical encoders, or three interferometers, whose signals provide feedback to a controller which actuates the linear motors accordingly.

Abstract: A linear DC motor adapted for driving a positioning table having a frame and a table displaceable in a linear direction has a toothed assembly affixed to one element thereof and an array of permanent magnets facing the toothed assembly mounted on the other element. Coils wound around the teeth of the toothed assembly and appropriately energized by DC produce a linear force which is effective to displace the table in a desired direction. When used with a position sensor and an appropriate control system, the table is controllable to a desired position. A set of brush members depending from the table contact a developed linear slip ring track for energizing the coils and for switching polarity of voltage to the coils at appropriate locations. In an embodiment where the coils are stationary on the frame and the magnets are disposed on the table, a power pickup arrangement movable with the brush members is incorporated into the brush and developed slip ring apparatus.

Abstract: A linear motor separates the functions of commutating into a first function for enabling a subset of coils in a linear stator which are within the magnetic influence of permanent magnets in the movable element and a second function for applying the drive power to the enabled subset. One pair of sensors produces sine and cosine signals to maintain a controd coils, the fiabout the phase of power which should be applied to the enabled subset. Another sensor produces a proportional signal which varies linearly between zero and one over each electrical quadrant with a short non-changing interval at maximum and minimum. The control system employs the sine, cosine and proportional signals to synthesize a pair of quasi-sinusoidal waveforms for application to alternate coils in the enabled subset of coils. The short non-changing intervals in the proportional signal are employed to ensure that polarity changeover to the enabled coils takes place at zero volts for bumpless drive.

Abstract: Air bearing pads for supporting a one-axis table in a granite bridge positioning apparatus on a thin film of air include machine-thinned sections for providing resilience to the pads in order to permit flexing sufficient to accommodate surface irregularities on the supporting surface. A single air pressure regulator provides a source of pressurized air to flow-control devices of a plurality of air bearing pads supporting a one-axis table. The individual flow-control devices adjust the flow of air to their respective air bearing pads to individually adjust the lift of the pads.

Abstract: A linear DC motor adapted for driving a positioning table having a frame and a table displaceable in a linear direction has a toothed assembly affixed to one element thereof and an array of permanent magnets facing the toothed assembly mounted on the other element. Coils wound around the teeth of the toothed assembly and appropriately energized by DC produce a linear force which is effective to displace the table in a desired direction. When used with a position sensor and an appropriate control system, the table is controllable to a desired position. A set of brush members depending from the table contact a developed linear slip ring track for energizing the coils and for switching polarity of voltage to the coils at appropriate locations. In an embodiment where the coils are stationary on the frame and the magnets are disposed on the table, a power pickup arrangement movable with the brush members is incorporated into the brush and developed slip ring apparatus.

Abstract: A high-precision positioning table employs magnetic attraction to guide a table along at least one axis. Precision roller bearings between flat guide ways provide the support. A linear DC motor provides force for positioning along an axis without backlash. The linear motor also contributes attractive force aiding in the guidance or retention of the table. A vacuum lock secures the table in a selected position.

Abstract: A control for a robotic actuator employs a position processor to determine the phase of a pair of electrooptically generated position signals as well as to keep track of the number of whole cycles of the position signals. Whole cycles are tracked using a prediction technique depending upon the continuity of position and velocity. A command processor employing the sensed position produces a velocity signal for driving the robotic actuator. When very slow motion is sensed, the response of the controller is appropriately reduced to maintain a velocity command signal generally in proportion to the motion.