Positioning system for a linear motor conveyor system

Abstract

Angular flux sensors may be spaced along a track of a linear conveyor system. The shuttle that moves on the track may include a magnet that allows the angular flux sensors to determine the position of the shuttle along the track. The flux extender can be included on the shuttle to direct the flux of the magnet. The conveyor system may use a main positioning system and a high resolution positioning system.

Description

POSITIONING SYSTEM FOR A LINEAR MOTOR CONVEYOR SYSTEMRELATED APPLICATIONS

[0001] The current disclosure claims priority to US Provisional Patent Application 63 / 570,559 file March 27th, 2024 and entitled “Positioning System for a Linear Motor Conveyor System,” the entire contents of which are incorporated herein by reference in their entirety for all purposes.TECHNICAL FIELD

[0002] The current disclosure relates to a positioning system for locating a shuttle on a conveyor, and in particular to a magnet-based positioning system.BACKGROUND

[0003] Linear motor conveyor systems use electromagnetics in order to move shuttles around a lineartrack. The shuttles may carry parts, components, tooling, etc. through a manufacturing, assembly, testing, etc. process. In order to control the electromagnetics it is necessary to know the location of the shuttles on the track. Further, it can be desirable to be able to determine a position of a shuttle in order to precisely position a shuttle, which may be useful in order to perform one or more operations on an object held on the shuttles.

[0004] An additional, alternative and or improved positioning system for locating shuttles on a track is desirable.BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Further features and advantages of the present disclosure will become apparent from the following detailed description, taken in combination with the appended drawings, in which:

[0006] FIG. 1 depicts a linear motor conveyor system;

[0007] FIG. 2 depicts a track section of a linear motor conveyor system;

[0008] FIG. 3 depicts a flux extender used with magnetic angle sensors;

[0009] FIGs. 4A and 4B depict details of a main positioning system of a linear motor conveyor system;

[0010] FIGs. 5A-5F depict various embodiments of flux extenders;

[0011] FIG. 6 depicts a method of determining a position of a shuttle on a track;

[0012] FIGs. 7A - 7C depict details of a high resolution positioning system;

[0013] FIG. 8 depicts operation of the high resolution positioning system;

[0014] FIG. 9 depicts a combined main positioning system and a high resolution positioning system;

[0015] FIG. 10 depicts a method of locating a shuttle on a track with high resolution; and

[0016] FIGs. 11A and 11 B depict a magnetic identification system for uniquely identifying shuttles.DETAILED DESCRIPTION

[0017] In accordance with the present disclosure, there is provided linear motor conveyor system comprising: a track section comprising a plurality of electromagnetic coils; a shuttle moveable along the track section by operation of the electromagnetic coils; a main positioning system for determining a position of the shuttle on the track section, the first positioning system comprising: at least one main positioning magnet arranged on a portion of the shuttle facing the track section, the magnetic flux of the main positioning magnet directed towards the track section; a plurality of magnetic angle sensors arranged at known locations along the track section to detect an angle of the magnetic flux, the angle of the magnetic flux detected by a respective magnetic angle sensor used to determine a position of the shuttle along the track section relative to the respective magnetic angle sensor.

[0018] In a further embodiment of the linear motor conveyor system, the shuttle further comprises a flux extender for guiding the magnetic flux from the at least one main positioning magnet towards the track section.

[0019] In a further embodiment of the linear motor conveyor system, the flux extender extends a width of the magnetic flux from the at least one main positioning magnet and contains a substantial majority of the magnetic flux to within a width of the shuttle.

[0020] In a further embodiment of the linear motor conveyor system, the flux extender provides a magnetic flux profile of the at least one main positioning magnet so that that angle of the magnetic flux changes approximately uniformly over the width of the magnetic profile.

[0021] In a further embodiment of the linear motor conveyor system, a magnitude of the magnetic flux is maintained within an operating range of the plurality of magnetic angle sensors.

[0022] In a further embodiment of the linear motor conveyor system, the magnetic flux extender is formed from a ferromagnetic material comprising a first arm and a second arm extending towards the track section with the at least one main positioning magnet arranged between the at least two extending arms.

[0023] In a further embodiment of the linear motor conveyor system, the at least one main positioning magnet comprises a plurality of magnets.

[0024] In a further embodiment of the linear motor conveyor system, the plurality of magnets are arranged with their poles in the same orientation.

[0025] In a further embodiment of the linear motor conveyor system, the flux extender comprises three arms formed of the ferromagnetic material.

[0026] In a further embodiment of the linear motor conveyor system, a first arm is arranged at a first end of the flux extender, a second arm is arranged at a second end of the flux extender, and a third arm is arranged between the first and the second arms.

[0027] In a further embodiment of the linear motor conveyor system, the plurality of magnetic angle sensors are spaced apart by a distance such that at least one magnetic angle sensor of the plurality of magnetic angle sensor scan detect the magnetic flux from the main positioning magnet for all shuttle positions on the track section.

[0028] In a further embodiment of the linear motor conveyor system, the system further comprises a second positioning system providing a higher positioning resolution than the main positioning system, the second positioning system comprising: a magnetic positioning target comprising a plurality of segments of periodically alternating magnetic poles affixed to the shuttle; a positioning sensor arranged at a known location along the track section to determinea high resolution position of a segment of the positioning target overlaying the positioning sensor.

[0029] In a further embodiment of the linear motor conveyor system, the main positioning system is used to determine which particular segment of the plurality of segments of the positioning target is overlaying the positing sensor in order to provide a high resolution position of the shuttle.

[0030] In a further embodiment of the linear motor conveyor system, the positioning sensor is one of a plurality of positioning sensors arranged at known locations along the track.

[0031] In a further embodiment of the linear motor conveyor system, each segment of the magnetic target has a fixed width, and wherein the main positioning system can locate the shuttle along the track with a greater resolution than the fixed width.

[0032] In a further embodiment of the linear motor conveyor system, the second positioning system providing a resolution of at least 5x greater than the resolution of the main positioning system.

[0033] In a further embodiment of the linear motor conveyor system, the system further comprises an identification system for uniquely identifying each shuttle, the identification system including a plurality of magnetic poles arranged at known locations on each shuttle, the orientation of the magnetic poles providing a binary encoding of a unique shuttle identifier.

[0034] In a further embodiment of the linear motor conveyor system, the identification system further comprises at least one magnetic sensor arranged on the track in a position to read the plurality of magnetic poles at the known locations on the shuttle.

[0035] In a further embodiment of the linear motor conveyor system, there are a plurality of magnetic sensors, with each of the plurality of the magnetic sensors arranged to read a respective one of the magnetic poles.

[0036] In a further embodiment of the linear motor conveyor system, the plurality of magnetic poles are read simultaneously by the magnetic sensors.

[0037] In accordance with the present disclosure, there is further provided a linear motor conveyor system comprising: a track section comprising a plurality of electromagnetic coils; a shuttle moveable along the track section by operation of the electromagnetic coils; a positioning system for determining a position of the shuttle on the track section; and an identification system comprising: a plurality of magnetic poles arranged at known locations on the shuttle, the plurality of magnetic poles encoding a unique identifier of the shuttle; and one or more magnetic sensor arranged to read the orientation of the plurality of magnetic poles based on a position of the shuttle determined by the positioning system.

[0038] In a further embodiment of the linear motor conveyor system, the number of the one or more magnetic sensor is equal to the number of the plurality of magnetic poles, and are arranged at corresponding locations as the magnetic poles to allow the plurality of magnetic poles to be read by the plurality of magnetic sensors simultaneously.

[0039] In a further embodiment of the linear motor conveyor system, the one or more magnetic sensors read at least a subset of the magnetic poles in series.

[0040] A positioning system for locating a shuttle on a track uses a main positioning magnet, or array of magnets, located on the shuttle. A plurality of magnetic angle sensors are arranged along the track and as the shuttle, and its main positioning magnet(s) pass a respective magnetic angle sensor, the sensor detects the angle of the magnetic flux and can determine a location of the main positioning magnet(s), and so the shuttle, relative to the magnetic angle sensor. The magnetic angle sensors are arranged on the track at known locations allowing the position of the shuttle on the track to be determined. A flux extender can be used on the shuttle in order direct, and extend, the magnetic flux generated by the main positioning magnet(s). The flux extender can allow the spacing between magnetic angle sensors to be increased. Further, the flux extender can help contain the magnetic flux from extending significantly beyond the flux extender, which may be within a width of a shuttle in order to avoid interfering with the positioning of adjacent shuttles.

[0041] The positioning system may use a main or primary positioning system that can determine the shuttle locations along the track with sufficient resolution to control the movement of the shuttle using the electromagnetic coils. While the positioning resolution of the main positioning system may be sufficient for a wide range of applications, it may be desirable in some scenariosto be able to determine the shuttle location at a higher resolution. A secondary or high resolution positioning system can be provided that can provide high resolution positioning of the shuttle. The high resolution positioning system may determine, with high resolution, the position of one of a plurality of target segments on the shuttle. The main positioning system can be used to determine which one of the plurality of target segments were measured by the high resolution positioning system, which allows the shuttle to be positioned with high resolution.

[0042] In addition to the main positioning system, and the high resolution positioning system, the conveyor system may also be provided with an identification system for identifying individual shuttles. The ID system comprises a plurality of magnetic poles arranged at known locations on the shuttle. The orientation of the magnetic poles can be used to encode a shuttle ID which can be read by one or more magnetic sensors. The location of the shuttle can be used in order to read the one or more magnetic sensors at times when the poles are arranged over the sensors.

[0043] FIG. 1 depicts a linear motor conveyor system. The conveyor system 100 comprises a plurality of track sections, including one or more straight sections 102a..102d (referred to collectively as straight sections 102) and curved sections 104a, 104b (referred to collectively as curved sections 104) connected together. As depicted in FIG. 1 the straight sections 102 and curved sections are arranged in order to provide a continuous loop of track. There are a wide range of possible configurations of a conveyor system that include both inside and outside corner sections of different radiuses, straight sections, etc. The conveyor system may be configured as a closed loop of track sections or may be open ended.

[0044] Regardless of the exact configuration of the track sections, one or more moveable shuttles are mounted on the track one of which is indicated by reference number 106. The track sections house electromagnetic coils which are controlled to provide a motive force to the individual shuttles. By controlling the power supplied to individual coils, it is possible to independently control the motion of the plurality shuttles on the track. A positioning system is used to locate shuttles along the track, which in turn can be used to control the appropriate coils in order to move the shuttle as desired. As described further below, a main positioning system can be provided for locating the shuttles with an acceptable resolution for a number of applications. For applications requiring greater positioning resolution a second high resolution positioning system can be provided. While the main positioning system is used to locateshuttles along the entire track, it is possible to provide the high resolution system only at specific locations along the track, although it can be provided along the entire track.

[0045] FIG. 2 depicts a track section of a linear motor conveyor system. The track section 202 provides one or more rails or guides that the shuttle can move along. A plurality of positioning sensors 206, 208 are arranged along a top of the track section. Although described as being on a top of the track section, it will be appreciated that the sensors 206, 208 can be arranged on other surfaces of the track section, although the sensor targets in the shuttle would need to be moved in order to be readable by the relocated sensors. The sensors 206, 208 may be arranged into sensor assemblies 210a, 210b, which can be mounted to the track section. Arranging the sensors into assemblies can simplify the installation of sensors on the track section; however, the sensors can be mounted and installed on the track section in a wide range of ways.

[0046] Two types of sensors are depicted in FIG. 2. The first type of sensors 206 are depicted as being mounted on a back or underside of the assemblies towards the shuttle surface of the track section. The first sensors 206 may comprise magnetic angle sensors that can determine an angle of the magnetic flux of a positioning magnet on the shuttle. The second sensors 208 may comprise high resolution sensors that are depicted as being arranged on a top of the assemblies. The high resolution sensors 208 can determine high resolution positioning of a segment of a plurality of periodic segments of a magnetic target. The magnetic target may be mounted on an underside of a protruding shuttle top 212 that positions the magnetic target over the high resolution sensors 208.

[0047] The main positioning system uses magnetic angle sensors in order to determine a position of the shuttle. A flux extender can be used to extend the width the magnetic flux travels from the positioning magnet, which in turn can reduce the number of magnetic angle sensors needed along a track section. Further, the flux extender tends to cause the magnetic flux to travel within the extender which tends to restrict the magnetic flux within the flux extender. Keeping a shuttle’s magnetic flux within the flux extender, which may be equal to or less than the shuttle’s width can reduce magnetic interference between the positioning magnets of adjacent shuttles, allowing positions of adjacent shuttles to be determined even if the adjacent shuttles are closely spaced to each other.

[0048] FIG. 3 depicts a flux extender used with magnetic angle sensors. The flux extender 302 is formed from a ferromagnetic material such as steel or iron. The flux extender guides the magnetic flux from the locating magnet in order to provide a magnetic flux profile that is better suited for positioning a shuttle. The magnetic flux profile of the magnet is extended in its width. The flux extender extends a width of the magnetic flux profile, and also contains most of the magnetic flux to approximately the width flux extender, which may match, or be less than, the width of the shuttle. Further, the magnetic flux profile provided by the magnet and flux extender, and in particular the angle of the magnetic flux changes approximately uniformly with distance and can also maintain a magnitude of the magnetic flux within an operating range of angle sensors.

[0049] The flux extender comprises a pair of outwardly extending arms 304a, 304b that extend towards the magnetic angle sensors. A permanent magnet 306 is arranged between the two extending arms. As depicted, the magnetic flux 308 is directed away from the magnet 306 towards respective arms 304a, 304b of the flux extender 302. The magnetic flux is directed within the arms and body of the flux extender back to the permanent magnet 306 as depicted by flux lines 310. The poles of the permanent magnet 306 can be reversed so that the direction of the magnetic flux is reversed.

[0050] The magnetic flux 310 from the magnet 306 can be detected by sensors that can determine the angle of the magnetic flux relative to the sensors. Three sensors 312a, 312b, 312c are depicted and different positions relative to the magnet 306 and flux extender 302. As depicted, each sensor may detect the angle of the magnetic flux which will differ depending upon where the sensors are located relative to the magnet and flux extender. The arrangement of the magnetic angle sensors and flux extender depicted in FIG. 3 can be incorporated into the linear conveyor system in order to provide a positioning system that can locate a shuttle along the track.

[0051] FIG. 4A depicts details of a main positioning system of a linear motor conveyor system using magnetic angle sensors. FIG. 4B depicts further details of the main positioning system without the body of the shuttle. A shuttle 402 moves along the track section and has a magnet 404 and a flux extender 406 arranged in order to direct the magnetic flux towards magnetic angle sensors 408 mounted along the track. The magnet angle sensors 408 may be mounted to a sensor frame or assembly 410 which can be secured to the track section, or the magneticangle sensors could be mounted directly to the track sections. With the position of the sensors fixed along the conveyor track, and the shuttle carrying the magnet and the flux extender only able to move along the track, the offset between the sensors and the magnet and the sensor remains fixed. With only a single degree of freedom in the relative movement between the shuttle and sensors, the determined angle can be mapped to a position of the shuttle relative to the sensor.

[0052] The magnetic flux, represented schematically by arrows 412, is directed from the magnet 404 to the extending arms of the flux extender 406. The magnetic angle sensors 408 are spaced apart along the track such that at least magnetic angle sensor can detect the magnetic flux regardless of the position of the shuttle along the track. As the shuttle 404 moves along the track as depicted by arrow 414, the flux angle detected by the sensor 408 will change and can be mapped to a position along the track relative to the sensor. Since the sensors are mounted along the track at known locations, the shuttle’s position determined relative to the sensors can be used to determine its location along the track.

[0053] The spacing between the arms of the flux extender 406 extends the magnetic flux from the magnet further outwards towards the arms. The magnet 404 may be positioned in the middle between the two arms. Additionally a magnetic plug or extender 416 may be placed on the magnet in order to extend the magnetic flux towards the track. By spacing the arms away from each other, the magnetic flux can be extended wider. The widening of the magnetic flux can reduce the number of magnetic angle sensors required along a track section. Reducing the number of magnetic angle sensors can reduce the complexity and cost of the conveyor system. In addition to widening the magnetic flux, the flux extender can also help restrict the edges of the flux so that they do not extend significantly beyond the width of the shuttle body. The shuttle body is depicted as being approximately 45mm (1.75 inches). Restricting the magnetic flux to be within the width of the shuttle helps to prevent the magnetic flux of one shuttle to interfere with the magnetic flux of an adjacent shuttle. That is, the flux extender can allow the positioning system to determine the position of respective shuttles even if the shuttles are adjacent one another.

[0054] In a particular embodiment the magnetic angle sensors may comprise a 24-bit magnetic on-axis angle sensors, although other angle sensors are possible, including both on-axis and off-axis angle sensors as well as more or fewer bits of resolution.. There may be 32 magneticangle sensors arranged along each meter long track section, which provides a spacing between sensors of approximately 31mm (1.22 inches). With a shuttle body width of approximately 48mm, the magnetic flux from the main positioning magnet on a shuttle will be detectable by at least one sensor at every shuttle position along the track. The width of the flux extender at the extending arms may approximately match the width of the shuttle body, although the width of the shuttle may be greater than the width of the extender. The ratio of the flux extender width to the distance between the sensors is at least one and may be approximately 3:2, 4:3, 5:4 or closer to 1 . The number of sensors, track length, and shuttle width are only illustrative and various different values can be used while still ensuring the shuttle can be located along the track section.

[0055] Certain previous shuttle positioning systems required the shuttle to move in order to determine its location. While such positioning systems may functional well while the conveyor system is in operation, it can present problems when the system is stopped and / or powered down. Additionally, since location of shuttles cannot be determined unless they were moving, it was not possible to determine if shuttles had been added or removed from the track while it was powered off. Such limitations made the powering on and startup of the conveyor system more difficult. The main positioning system described herein can detect the shuttles and determine their locations on the track even when the shuttles are stationary. The positioning system is also able to detect the presence of shuttles and as such can determine if shuttles have been added or removed from the conveyor system.

[0056] The above has described a positioning system that uses a flux extender arranged on a shuttle in order to extend the magnetic flux from a centrally located magnet. The flux extender extends the width of the magnetic flux while maintaining the magnitude of the magnetic flux within the operating range of the magnetic angle sensors. While a particular flux extender is described above, it will be appreciated that a wide range of various embodiments are possible as described further below.

[0057] The flux of a magnet goes from the north pole of the magnet to the south pole. Without the flux extender, the flux would follow a short path around the magnet. While it is possible magnetic angle sensors may be able to detect the angle of the magnetic flux without the flux extender, additional sensors may be required as the width of the flux is less. The flux extenderdraws the flux out to the arms creating a wider area where the flux is at a magnitude suitable for sensing and as such, fewer magnetic angle sensors can be used.

[0058] It will be appreciated that different arrangements of the flux extender are possible with varying arrangements of magnets and arms. For the magnetic angle sensors to work, the magnitude of the flux at the sensor needs to be between defined operating limits of the sensor. As the arms of the flux extender are separated further from each other, a more powerful magnet is needed in the middle in order to have the magnetic flux extend from the magnet to the arms. However, such an arrangement may result in the magnitude of the flux at the middle of the arms being above the operating range of the sensor, while the magnitude of the flux at the arms may be below the operating range of the sensor. Different sensors may have different functional ranges. The particular design of the flux extender, including its material, shape, size, number of magnets, magnet locations and orientations, magnet strengths may be varied in order to achieve the desired magnetic field strength and shape.

[0059] FIGs. 5A-5F depict various embodiments of flux extenders. The various embodiments 500a..500f of the flux extender and magnets all extend the width of the flux of the magnets. As described above, it is desirable to have the magnitude of magnetic flux within the magnetic angle sensor’s operating range. The flux extender 500a is depicted as comprising a pair of extending arms 502a-a, 502a-b with a plurality of magnets 504a-a, 504a-b, 504a-c arranged in between the arms. A central magnet 504a-a is depicted as being surrounded on each side by outside magnets 504a-b, 504a-c. All of the magnets 504a-a..504a-c are arranged with their poles in the same orientation. The outside magnets 504a-b, 504a-c help to have the magnitude of the magnetic flux remain within the operating range of the sensors as it extends towards the arms 502a-a, 502a-b.

[0060] The flux extender 500b is depicted as having two arms 502b-a and 502b-b. Magnets 504b-a, 504b-b are arranged on each of the arms 502b-a, 502b-b with a central magnet 502b- c located between the two. The two magnets 504b-a and 504b-b on the outside arms have their poles arranged in the same orientation while the central magnet 504b-c has the pole arranged in the opposite orientation. Each of the arms 502b-a and 502b-b have extensions 506b-a, 506b-b that extend beside the magnets and tend to guide the magnetic flux into the flux extender in order to maintain the magnetic flux within a width of the flux extender.

[0061] The flux extender 500c is depicted as having a pair of extending arms 502c-a, 502c-b with an array of magnets 504c arranged between the two arms. The magnets 504c are arranged in an arc shape which tends to direct the magnetic flux towards the extending arms 502c-a, 502c-a.

[0062] The flux extender 500d is depicted as having two arms 502d-a and 50db-b. Magnets 504d-a, 504d-b are arranged on each of the arms 502d-a, 502d-b with a central magnet 502d- c located between the two. The two magnets 504d-a and 504d-b on the outside arms have their poles arranged in the same orientation while the central magnet 504d-c has the pole arranged in the opposite orientation.

[0063] The flux extender 500e is depicted as having the extending arms 502e-a, 502e-b arranged in a ‘V’ shape with a magnet 504e arranged in the middle between the arms 502e-a, 502e-b.

[0064] The flux extender 500f is depicted as having the extending arms 502f-a, 502f-b arranged in an arcuate shape with a magnet 504f arranged in the middle between the arms 502f-a, 502f- b.

[0065] FIG. 6 depicts a method of determining a position of a shuttle on a track. The method 600 assumes that the conveyor system is powered down and that the location of shuttles on the conveyor system is unknown. First the conveyor system is powered on (602). Powering on the conveyor system supplies power to the electronics of the system, however does not supply power to the coils used to move the shuttles along the track. With the system powered on, each of the magnetic angle sensors are read in order to determine if there is a shuttle within the sensor’s vicinity and if there is the angle of the magnetic flux (604). In method 600 it is assumed that there is only a single shuttle on the conveyor system, however in practice there may be a plurality of shuttles on each track section. The system can determine the position of each shuttle independently. Once the angle of the magnetic flux is determined, it is used to determine the shuttle position (606). The flux angle measured by the magnetic angle sensor may be mapped to a location along the track. The flux angle measured by sensors can be mapped to a track location during a calibration process to more accurately locate the shuttle along the track. In addition to calibrating the sensor readings in order to map them back to a track location, the individual magnetic flux sensors may also be calibrated in order to properlydetect the flux angles. The particular calibration process for the individual sensors may depend on the specific sensors used. For example, it may be necessary to rotate the magnetic flux field through a number of full rotations as detected by the sensor. In such a calibration process, one or more shuttles may pass in front of the sensor on the track in order to expose the sensor to the required magnetic flux angles. It will be appreciated that other calibration processes may be used in order to properly calibrate the sensors.

[0066] Once the initial positions of all of the shuttles are determined along the track, the power to the coils are controlled in order to move the shuttles as required (608). The positions of the shuttles are determined in real-time as the shuttles move in orderto accurately control the drive coils that move the shuttles as required. The real-time positioning reads the flux angle of the sensors (610) and maps the flux angle to a respective on-track position of the shuttle (612). Controlling the coils, and determining the position of the shuttles continues while the conveyor system is in operation. The movement of the shuttles can be controlled to move to specific locations along the conveyor track in order to have one or more operations performed.

[0067] The above has described a main positioning system that uses at least one main positioning magnet located on the shuttle in order to determine the position of the shuttle using a measured angle of the magnetic flux. The main positioning system described above can position the shuttle on the track with sufficient accuracy to position the shuttles as needed for a number of applications. While the positioning accuracy of the main positioning system may be good enough for a number of applications, there may be applications that require, or at least would benefit from, a positioning system that provides a higher resolution of the shuttle positioning.

[0068] FIGs. 7A - 7C depict details of a high resolution positioning system. A high resolution positioning system may be used to determine the position of a shuttle 702 with greater accuracy than the main positioning system described above. For example, the high resolution positioning system may provide 5x - 10x or greater positioning accuracy compared to the main positioning system. As described further below, the shuttle may include a positioning target mounted on an underside of an upper pallet connection 706 that extends over the high resolution sensors. Other arrangements of the sensors on the track and the positioning target on the shuttle are possible. The positioning target passes over the high resolution sensors as the shuttle moves on the track. The positioning target comprises a plurality of repeating segments. The highresolution positioning system can determine, with high accuracy, a position of one of the segments of the positioning target, however, the high resolution positioning system cannot distinguish among the different segments on the positioning target. In order to determine the high resolution position of the shuttle, the main positioning system is used to determine the specific segment of the positioning target that is being located by the high resolution positioning system. That is, the main positioning system can be used to determine which particular segment of the high-resolution positioning target is over the high resolution sensor. Accordingly, the positioning resolution of the main positioning system is at least as high as the segment sizes of the high resolution positioning target.

[0069] The high resolution positing system comprises one or more high resolution sensors 704 that can be located along a sensor frame 410 or track section. The high resolution sensors 704 may be spaced apart along the track segment in order to provide high resolution positioning along the entire track segment. However, it may not be necessary to provide high resolution positioning of the shuttle across the entire conveyor system. High resolution sensors may only be provided in areas along the conveyor system where the additional positioning resolution provided by the high resolution sensors is desirable. The high resolution sensor may be provided by a linear or rotary encoder. The high resolution sensors may provide a positioning resolution of about 5pm to 1 pm.

[0070] FIG. 7B depicts the shuttle 702 with a top pallet 706 removed in order to depict the positioning plate 708 that is located on an underside of the top pallet 706. The bottom of the positioning plate 708 is depicted in FIG. 7C. The bottom of the positioning plate comprises a positioning target 710 that comprises a plurality of alternating magnetic poles arranged in a repeating pattern, with pairs of the alternating poles providing the target segments. Different sensors may have different requirements for the pole size and spacing. For example a sensor may use alternating magnetic poles that have a width of 2mm each. With a pole width of 2mm, a 12 bit linear encoder can provide positioning resolution of approximately 1pm. Regardless of the particular dimensions of the magnetic poles, they are arranged in an alternating pattern. The pattern provides a plurality of segments, each comprising two adjacent magnetic poles. The high resolution sensors can determine the position of a segment with micrometer accuracy, however it is not possible to distinguish which of the particular segments are being located. In order to be able to determine the shuttle positioning using the high resolution sensors, it isnecessary to determine which particular segment is being detected by the sensor. The main positioning system described above can position the shuttle with enough accuracy in order to determine which segment is overlaying the high resolution sensor.

[0071] FIG 8 depicts operation of the high resolution positioning system. As depicted, the alternating repeating magnetic poles of the positioning target 710 can be viewed as forming a plurality of adjacent segments A, B, C, D, E. As the positioning target 710 passes over a sensor, the sensor can determine the relative position of the segment that is overlaying the sensor 704. As the positioning target 710 continues to move over the sensor, the sensor provides an absolute position of the segment relative to the sensor. The positions determined by the sensor are depicted as being 0mm, 1mm, 2mm, 3mm and 4mm, however it will be appreciated that the sensor can provide the position of a segment with micrometer accuracy. As depicted, once the initial segment being measured passes over the sensor 704, or the sensor has reached its maximum range, the sensor begins measuring the position of the next segment. As such, as the positioning target 710 moves across the sensor the position output from the sensor goes from 0mm to 4mm before returning to 0mm for the next segment. The specific segment of the positioning target that is being located by the sensor is determined by the main positioning system. In order to determine the specific segment being measured by the high resolution sensor, the main positioning system must have a positioning accuracy of at least the segment width.

[0072] FIG. 9 depicts a combined main positioning system and a high resolution positioning system. The combined positioning system 900 comprises a main positioning system that comprises a plurality of main positioning sensors 408 arranged along the track. Each of the main positioning sensors 408 can detect a main positioning target 404, which is described as being a permanent magnet above. As depicted, the each of the main positioning sensors 408 can detect the main positioning target 404 and determine a position of the shuttle. Using the position of the shuttle, and the known position of one or more high resolution sensors 704, it is possible to determine which one of the plurality of segments A, B, C, D, E, of the high resolution positioning target is being measured, or located, by the high resolution sensor 704. The high resolution position of the segment determined by the high resolution sensor can be combined with the particular segment determined by the main positioning system to determine with high resolution the position of the shuttle. The location of each segment on the high resolutionpositioning target may be known and as such, combining the high resolution position of the segment and the known location of the segment on the shuttle, it is possible to provide a location of the shuttle with high resolution, such as approximately 1 pm.

[0073] FIG. 10 depicts a method of locating a shuttle on a track with high resolution. The method 1000 determines a high resolution position of a segment of a plurality of segments on a high resolution positioning target (1002) on the shuttle with the segments comprising a plurality of periodically arranged magnetic poles. The position of the shuttle is determined using the main positioning system (1004). The position of the shuttle determined using the main positioning system is used to determine the particular segment of the high resolution positioning target that is being located by the high resolution sensor (1006). The high resolution position of the shuttle is determined using the high resolution position of the particular segment determined by the main positioning system (1008).

[0074] The above has described a flexible positioning system for a conveyor system. The positioning system may use a main positioning system that can be used to determine the position of a shuttle along the entire length of the track. The main positioning system can provide sufficient positioning accuracy to determine, and so control, the position of the shuttle for a range of applications. A second positioning system can be provided that cooperates with the main positioning system in order to provide greater accuracy in the positioning of the shuttle. The high resolution positioning system can be provided along the entire length of the conveyor track, or may be provided at particular locations or sections of the track where additional positioning accuracy is required or determined.

[0075] The above has described positioning systems that can be used to determine the specific location of individual shuttles along a conveyor track. However, the positioning system is unable to distinguish between the individual shuttles on the track. As described further below, the conveyor system may be provided with an identification (ID) system to uniquely identify each individual shuttle. The ID system may provide a low cost implementation to ID each shuttle. Since the ID system is relatively low cost, it can be implemented on each track segment allowing the shuttle ID to be determined at each segment.

[0076] FIGs. 11A, 11B depict a magnetic identification system for uniquely identifying shuttles. The shuttle ID system comprises a plurality of magnetic sensors 1102 arranged on the sensorframe 410, or on the track section. The plurality of magnetic sensors 1102 may be low cost hall-effect sensors which are able to detect a pole of a magnet that is positioned over the sensor. The plurality of magnetic sensors 1102 are arranged in an orientation 1104 that allows a plurality of magnets arranged on the bottom of the positioning plate 708 to be simultaneously read by the sensors. As depicted in FIG. 11B, the bottom of the positioning plate 708 includes the high resolution positioning target 710 as well as a plurality of ID magnets arranged in a position to be read by the magnetic sensors 1102. The ID magnets 1106 are depicted as comprising 19 magnetic poles whose orientation can encode a 19-bit value used as a unique identifier. With 19 magnetic poles, the ID system can uniquely identify 524,288 shuttles. The number of magnetic poles may be increased or decreased in order to increase or decrease the number of unique IDs available. The positioning system may be used in order to determine when the shuttle is positioned so that the ID magnets are over the corresponding ID sensors. The sensors can be read when the ID magnets are over the corresponding sensors and so determine the unique shuttle ID.

[0077] The ID system described above uses individual magnetic sensors to read each magnetic pole of the ID magnets. As such, all of the magnets can be read simultaneously in parallel. It will be appreciated that a similar ID system can be provided that uses fewer sensors to read the magnetic poles serially as the shuttle moves over the sensor. For example, two magnetic sensors can be arranged to read each row of the magnetic poles on the positioning plate 708 as the shuttle, and so the ID magnets, move over the sensors.

[0078] The ID system is relatively low cost to implement allowing the ID sensors to be positioned frequently along the conveyor system, such as on each track section. As such, it is possible to uniquely ID each shuttle quickly as they move on the conveyor system

[0079] It will be appreciated by one of ordinary skill in the art that the system and components shown in FIGs. 1 - 11B may include components and / or steps not shown in the drawings. For simplicity and clarity of the illustration, elements in the figures are not necessarily to scale, are only schematic and are non-limiting of the elements structures. It will be apparent to persons skilled in the art that a number of variations and modifications can be made without departing from the scope of the invention as defined in the claims.

[0080] Although certain components and steps have been described, it is contemplated that individually described components, as well as steps, may be combined together into fewer components or steps or the steps may be performed sequentially, non-sequentially or concurrently. Further, although described above as occurring in a particular order, one of ordinary skill in the art having regard to the current teachings will appreciate that the particular order of certain steps relative to other steps may be changed. Similarly, individual components or steps may be provided by a plurality of components or steps. One of ordinary skill in the art having regard to the current teachings will appreciate that the components and processes described herein may be provided by various combinations of software, firmware and / or hardware, other than the specific implementations described herein as illustrative examples.

[0081] The techniques of various embodiments may be implemented using software, hardware and / or a combination of software and hardware. Various embodiments are directed to apparatus, e.g. a node which may be used in a communications system or data storage system. Various embodiments are also directed to non-transitory machine, e.g., computer, readable medium, e.g., ROM, RAM, CDs, hard discs, etc., which include machine readable instructions for controlling a machine, e.g., processor to implement one, more or all of the steps of the described method or methods.

[0082] Some embodiments are directed to a computer program product comprising a computer- readable medium comprising code for causing a computer, or multiple computers, to implement various functions, steps, acts and / or operations, e.g. one or more or all of the steps described above. Depending on the embodiment, the computer program product can, and sometimes does, include different code for each step to be performed. Thus, the computer program product may, and sometimes does, include code for each individual step of a method, e.g., a method of operating a communications device, e.g., a wireless terminal or node. The code may be in the form of machine, e.g., computer, executable instructions stored on a computer- readable medium such as a RAM (Random Access Memory), ROM (Read Only Memory) or other type of storage device. In addition to being directed to a computer program product, some embodiments are directed to a processor configured to implement one or more of the various functions, steps, acts and / or operations of one or more methods described above. Accordingly, some embodiments are directed to a processor, e.g., CPU, configured toimplement some or all of the steps of the method(s) described herein. The processor may be for use in, e.g., a communications device or other device described in the present application.

[0083] Numerous additional variations on the methods and apparatus of the various embodiments described above will be apparent to those skilled in the art in view of the above description. Such variations are to be considered within the scope of the current disclosure.

Claims

WHAT IS CLAIMED IS:

1. A linear motor conveyor system comprising: a track section comprising a plurality of electromagnetic coils; a shuttle moveable along the track section by operation of the electromagnetic coils; a main positioning system for determining a position of the shuttle on the track section, the first positioning system comprising: at least one main positioning magnet arranged on a portion of the shuttle facing the track section, the magnetic flux of the main positioning magnet directed towards the track section; a plurality of magnetic angle sensors arranged at known locations along the track section to detect an angle of the magnetic flux, the angle of the magnetic flux detected by a respective magnetic angle sensor used to determine a position of the shuttle along the track section relative to the respective magnetic angle sensor.2 The linear motor conveyor system of claim 1 , wherein the shuttle further comprises a flux extender for guiding the magnetic flux from the at least one main positioning magnet towards the track section.3 The linear motor conveyor system of claim 2, wherein the flux extender extends a width of the magnetic flux from the at least one main positioning magnet and contains a substantial majority of the magnetic flux to within a width of the shuttle.4 The linear motor conveyor system of claim 3, wherein the flux extender provides a magnetic flux profile of the at least one main positioning magnet so that that angle of the magnetic flux changes approximately uniformly over the width of the magnetic profile.5 The linear motor conveyor system of claim 4, wherein a magnitude of the magnetic flux is maintained within an operating range of the plurality of magnetic angle sensors.6 The linear motor conveyor system of any one of claims 2 to 5, wherein the magnetic flux extender is formed from a ferromagnetic material comprising a first arm and a secondarm extending towards the track section with the at least one main positioning magnet arranged between the at least two extending arms.

7. The linear motor conveyor system of any one of claims 2 to 5, wherein the at least one main positioning magnet comprises a plurality of magnets.8 The linear motor conveyor system of claim 7, wherein the plurality of magnets are arranged with their poles in the same orientation.9 The linear motor conveyor system of any one of claims 2 to 8, wherein the flux extender comprises three arms formed of the ferromagnetic material.10 The linear motor conveyor system of claim 9, wherein a first arm is arranged at a first end of the flux extender, a second arm is arranged at a second end of the flux extender, and a third arm is arranged between the first and the second arms.11 The linear motor conveyor system of any one of claims 1 to 10, wherein the plurality of magnetic angle sensors are spaced apart by a distance such that at least one magnetic angle sensor of the plurality of magnetic angle sensor scan detect the magnetic flux from the main positioning magnet for all shuttle positions on the track section.12 The linear motor conveyor system of any one of claims 1 to 11 , further comprising a second positioning system providing a higher positioning resolution than the main positioning system, the second positioning system comprising: a magnetic positioning target comprising a plurality of segments of periodically alternating magnetic poles affixed to the shuttle; a positioning sensor arranged at a known location along the track section to determine a high resolution position of a segment of the positioning target overlaying the positioning sensor.13 The linear motor conveyor system of claim 12, wherein the main positioning system is used to determine which particular segment of the plurality of segments of the positioningtarget is overlaying the positing sensor in order to provide a high resolution position of the shuttle.

14. The linear motor conveyor system of claim 12 or 13, wherein the positioning sensor is one of a plurality of positioning sensors arranged at known locations along the track.

15. The linear motor conveyor system of any one of claims 12 to 14, wherein each segment of the magnetic target has a fixed width, and wherein the main positioning system can locate the shuttle along the track with a greater resolution than the fixed width.

16. The linear motor conveyor system of claim 15, wherein the second positioning system providing a resolution of at least 5x greater than the resolution of the main positioning system.

17. The linear motor conveyor system of any one of claims 1 to 16, further comprising an identification system for uniquely identifying each shuttle, the identification system including a plurality of magnetic poles arranged at known locations on each shuttle, the orientation of the magnetic poles providing a binary encoding of a unique shuttle identifier.

18. The linear motor conveyor system of claim 17, wherein the identification system further comprises at least one magnetic sensor arranged on the track in a position to read the plurality of magnetic poles at the known locations on the shuttle.

19. The linear motor conveyor system of claim 18, wherein there are a plurality of magnetic sensors, with each of the plurality of the magnetic sensors arranged to read a respective one of the magnetic poles.

20. The linear motor conveyor system of claim 19, wherein the plurality of magnetic poles are read simultaneously by the magnetic sensors.

21. A linear motor conveyor system comprising: a track section comprising a plurality of electromagnetic coils; a shuttle moveable along the track section by operation of the electromagnetic coils; a positioning system for determining a position of the shuttle on the track section; andan identification system comprising: a plurality of magnetic poles arranged at known locations on the shuttle, the plurality of magnetic poles encoding a unique identifier of the shuttle; and one or more magnetic sensor arranged to read the orientation of the plurality of magnetic poles based on a position of the shuttle determined by the positioning system.

22. The linear motor conveyor system of claim 21 , wherein the number of the one or more magnetic sensor is equal to the number of the plurality of magnetic poles, and are arranged at corresponding locations as the magnetic poles to allow the plurality of magnetic poles to be read by the plurality of magnetic sensors simultaneously.

23. The linear motor conveyor system of claim 22, wherein the one or more magnetic sensors read at least a subset of the magnetic poles in series.

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