SE1951060A1 - Wireless identification tags and corresponding readers - Google Patents

Abstract

Construction equipment (100, 1600) comprising a rotatable work tool (102), a wireless identification tag reader (120), and a control unit (140), wherein the rotatable work tool (102) comprises a wireless identification tag (110) configured to store data configured to be accessible via the wireless identification tag reader (120).

Description

TITLE WIRELESS IDENTIFICATION TAGS AND CORRESPONDING READERS TECHNICAL FIELD The present disclosure relates to wireless identification tags, correspondingreaders, and to systems comprising both tag and reader. The disclosed tagsare particularly suitable for use with rotatable heavy-duty work tools, such ascut-off discs, core drills, and abrasive tools for use on stone, concrete, and thelike.

BACKGROUND Radio-frequency identification (RFID) technology uses electromagnetic fieldsto automatically identify and track tags attached to objects. The tags oftencontain electronically stored information such as an identification number.While active tags have a local power source (such as a battery) and mayoperate hundreds of meters from the RFID reader, passive tags collect energyfrom a nearby RFID reader's interrogating electromagnetic field and thereforehas a reduced range. Unlike a barcode, the tag need not be within line of sightof the reader, so it may be embedded in the tracked object.

RFID tags are used in many industries. For example, an RFID tag attached toa work tool such as a cut-off disc can be used to identify the type of discattached to the tool.

EP 2 460 623 A2 discloses an example use of RFID technology with rotatable work tools.

Embedding wireless identification tags into metallic objects, such as a cut-offdisc, is problematic since the high electrical conductivity of the metalsurrounding the hole in which the tag is placed generates opposing magneticflux that cancels out the magnetic flux through the hole. This effect, described by the Maxwell-Faraday equation, complicates interacting with the tag by areader.

There is a need for improved wireless identification tag systems suitable for embedding into electrically conductive surfaces, such as a metal work tool.

SUMMARY lt is an object of the present disclosure to provide wireless identification tags,readers, and systems where the tags are suitable for embedding intoelectrically conductive surfaces. This object is at least in part obtained by awireless identification tag for embedding into an electrically conductive surfaceof a rotatable work tool. The tag comprises at least a first and a secondinductive planar loop having corresponding first and second terminals. The firstinductive planar loop and the second inductive planar loop are arranged inrelation to a common plane. The first inductive planar loop and the secondinductive planar loop are also arranged to cover different areas of the commonplane, where each area on the common plane is associated with a respective polarity of the magnetic flux normal to said plane.

This way the wireless tag is not 'quenched' by the electrically conductivesurface. Rather, the tag is matched to a magnetic flux with varying polarity.Consequently, there is provided a wireless identification tag suitable for embedding into electrically conductive surfaces.

The rotatable work tool may, e.g., be a cut-off disc or a drill, such as a coredrill.

According to aspects, the areas are separable by a line drawn on the commonplane or by an arc of a circle having a radius drawn on the common plane. Thisapproach to separation is particularly suitable for rotatable work tools.

According to aspects, the wireless identification tag comprises three or moreinductive planar loops, wherein each inductive planar loop is arranged to covera different area of the common plane, where each area is associated with arespective polarity of the magnetic flux normal to said plane. This way a wide variety of geometries can be used when embedding the tag into the electricallyconductive surface. A tag thus matched to a magnetic field with varying fluxpolarity provides improved performance in terms of both inductive coupling and communication ability with respect to a tag reader.

According to aspects, the wireless identification tag comprises a connectingnetwork configured to serially connect the first and the second inductive p|anarloops, thereby increasing a total voltage induced by the first and the secondinductive p|anar loop in response to changes in a magnetic flux. This improveswireless identification tag communication range and energy transfer ability withrespect to the reader, which is an advantage. Also, the physical footprint of thetag can be reduced since the efficiency is increased, which is an advantage.

According to aspects, the wireless identification tag comprises a connectingnetwork configured to connect the first and the second inductive p|anar loopsin parallel, thereby reducing a source resistance associated with the wirelessidentification tag. A reduced source resistance may be advantageous in certain applications.

According to aspects, the wireless identification tag comprises an identificationcircuit connected to the first inductive p|anar loop and to the second inductivep|anar loop. The identification circuit is arranged to modulate a load on theterminals of a circuit formed by the connection of the first inductive p|anar loopand the second inductive p|anar loop, thereby providing an inductivecommunication channel to a wireless identification tag reader. This way awireless identification tag system is formed that allows communicationbetween the tag and a corresponding tag reader in an efficient manner.

According to aspects, the identification circuit is arranged to be powered viathe first and second inductive p|anar loops. By powering the identificationcircuit via the inductive loops, there is no need for a dedicated power sourceon the tag, such as a battery or the like, which is an advantage.

According to aspects, the identification circuit is arranged to store identificationdata. This enables, e.g., detecting what type of tool that is currently in use, and verifying that the tool is the correct one for the present application. Theidentification data also simplifies inventory management and the like.

According to aspects, the identification circuit is arranged to determine atemperature value. This enables an operator to read out temperature data andto, e.g., determine if a tool has been subject to overheating or the like. Also,overheating may be detected during tool use and a warning signal may beissued to the operator who may cease operation.

According to aspects, the identification circuit is arranged to determine anacceleration value. By determining acceleration value, a plurality of applications is enabled, which applications will be discussed in the following.

According to some other aspects, the identification circuit is arranged toreceive data from the wireless identification tag reader, and to store the data.This enables, e.g., the reader, or a control unit connected to the reader, tomeasure operating time for a given tool, and to update an operating timeparameter of the tool. A user can then read out the operating time parameterand thereby obtain information about how long a given tool has been used.The reader and/or control unit may also determine one or more operatingconditions and store this information in the tool, by the identification circuit. Theoperating conditions may, e.g., comprise a user identity or authorization code,a time of day, a day of the week, and the like.

There are also disclosed herein wireless identification tag readers, wirelessidentification tag systems, blade guards, work tools and applicationsassociated with at least some of the above-mentioned advantages. There isfurthermore disclosed herein control units, computer programs, computerreadable media, computer program products, and vehicles associated with theabove discussed advantages.

There is furthermore disclosed herein a wireless identification tag forembedding into a rotatable work tool. The tag comprises at least a firstinductive loop, an energy storage device, processing circuitry, and a radiofrequency transceiver. The wireless identification tag is arranged to harvest electrical energy from a time varying magnetic flux by the first inductive planar loop and to store the electrical energy in the energy storage device. Theprocessing circuitry and the radio frequency transceiver are arranged to bepowered by the energy storage device. The energy storage device may, e.g., be a capacitor or a battery.

Thus, advantageously, there is no need for battery replacement or otherexternal power source in the tag, since the tag harvests energy for its operationfrom the time varying magnetic flux. This time varying magnetic flux may beobtained, e.g., by arranging one or more permanent magnets along a rotationalpath of the wireless identification tag, e.g., in connection to a blade guard orthe like. The radio frequency transceiver allows for wireless linkage betweenthe tag an, e.g., a control unit, thereby avoiding complicated and costly wiringcomprising a dedicated wireless tag reader.

The wireless identification tag may further comprise the identification circuit discussed above; in which case the identification circuit can becommunicatively coupled to an exterior unit via the radio frequencytransceiver. The identification circuit application discussed above are therefore enabled also here.

A blade guard comprising one or more permanent magnets arranged to powera wireless identification tag arranged embedded in a rotatable work tool is alsodisclosed herein. The permanent magnets may be arranged in relation to acircular arc centered at a rotational center of the rotatable work tool. Thepermanent magnets may be arranged with alternating polarity along the circular arc.

There is furthermore disclosed herein construction equipment comprising awireless identification tag, a blade guard, and a control unit arranged tocommunicate with the wireless identification tag via radio link.

Generally, all terms used in the claims are to be interpreted according to theirordinary meaning in the technical field, unless explicitly defined otherwiseherein. All references to "a/an/the element, apparatus, component, means,step, etc." are to be interpreted openly as referring to at least one instance ofthe element, apparatus, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to beperformed in the exact order disclosed, unless explicitly stated. Furtherfeatures of, and advantages with, the present invention will become apparentwhen studying the appended claims and the following description. The skilledperson realizes that different features of the present invention may becombined to create embodiments other than those described in the following,without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present disclosure will now be described in more detail with reference tothe appended drawings, where Figure 1 shows an example work tool; Figures 2-3 schematically illustrate example wireless identification tags;Figure 4 illustrates a wireless identification tag embedded in a work tool;Figure 5 shows an example wireless identification tag reader; Figure 6 is a flow chart illustrating methods; Figures 7-9 show example holes in an electrically conductive surface;Figure 10 shows an example control unit; Figure 11 illustrates a computer readable medium; Figure 12 schematically illustrates a work tool with an embedded tag;Figures 13A and 13B schematically illustrate magnetic flux; Figure 14 shows an example work tool; Figure 15 schematically illustrates a wireless identification tag; and Figure 16 shows an example work tool; DETAILED DESCRIPTION The invention will now be described more fully hereinafter with reference to theaccompanying drawings, in which certain aspects of the invention are shown.This invention may, however, be embodied in many different forms and shouldnot be construed as limited to the embodiments and aspects set forth herein;rather, these embodiments are provided by way of example so that thisdisclosure will be thorough and complete, and will fully convey the scope ofthe invention to those skilled in the art. Like numbers refer to like elementsthroughout the description. lt is to be understood that the present invention is not limited to theembodiments described herein and illustrated in the drawings; rather, theskilled person will recognize that many changes and modifications may bemade within the scope of the appended claims.

Figure 1 shows construction equipment 100 for cutting hard materials such asconcrete and stone by a work tool 102, here exemplified by a cut-off disc.

The work tool 102 may be in the form of a blade, such as a diamond bladecomprising cutting segments with diamonds arranged along a periphery of theblade.

The tool 102 is made of metal, which means that its surface 101 is electricallyconductive. The work tool 102 rotates in direction D about a center of rotationC. The direction D is shown as a 'down-cut' direction in Figure 1, however, 'up-cut' operation where the work tool 102 rotates in the opposite direction is alsopossible. Figures 14 and 16 show similar equipment 1400, 1600.

Construction equipment 100, 1400, 1600 such as the cut-off tool shown inFigures 1 and 14, 16 are known in general and will not be discussed in more detail herein.

With reference to Figures 1 and 16, the work tool 102 comprises a wirelessidentification tag 110 arranged embedded into the electrically conductivesurface 101. The wireless identification tag 110 may be embedded in a circularhole cut in the surface 101 _ The circular hole may be a laser-cut hole extendingthrough the work tool 102. Alternatively, the wireless identification tag may beembedded in a recess formed in the work tool, i.e., not a hole though the tool.

The tag 110 is arranged at a radial distance R from a center of rotation C ofthe work tool, which means that it will move along a circular arc 130 with radiusR when the work tool 102 is in use.

The tag 110 is preferably arranged at a radial distance R below two thirds ofthe radius of the work tool 102. For instance, if the radius of the work tool 102is 17,5 cm, then the tag 110 should preferably be placed at a radial distancebelow 11 cm.

According to aspects, the tag 110 is preferably arranged at a radial distance R above one third of the radius of the work tool 102.

Placing the tag too close to the edge of the rotatable work tool may cause thetag to overheat. However, some measurements of, e.g., tool temperature are more accurate if obtained close to the edge.

The larger the radial distance R the larger the rotational velocity, meaning thatless time is available for powering and reading the tag 110 by the reader 120.

Preferably, the wireless identification tag 110 is arranged away from a blade tensioning zone.

Figure 14 also shows a work tool 102 comprising a wireless identification tag1410. The two tags 110, 1410 differ in the way they are supplied with electricalenergy and in how data stored on the tag is accessed, as will be made clearbelow where Figure 14 is discussed in more detail. Other than the differencesin how the tags are powered and in how data is read out from the tags, theyare similar and support the same type of applications. ln particular, the twotags 110, 1410 can be used for the same purposes with the same technicaleffects and are therefore associated with the same advantages. ln particular,the identification circuits and applications discussed below can beimplemented on any of the wireless identification tags 110, 1410 discussed herein.

Consequently, there is disclosed herein a work tool 102, wherein a wirelessidentification tag 110, 1410 is configured to rotate about a center of rotation Cduring operation of the work tool.

With reference to Figure 1, each revolution of the work tool 102, the wirelessidentification tag 110 passes a wireless identification tag reader 120 arrangedon a blade guard 103 of the construction equipment 100. The reader 120 isaligned with the tag 110 in the sense that it is arranged on the circular arc 130at the same radial distance R from the center of rotation C as the tag, suchthat the tag passes more or less directly under the reader each revolution. Theconstruction equipment discussed herein may be hand-held constructionequipment or other types of construction equipment, including more heavytypes of machinery such as floor saws, floor grinders, and the like. Therotatable work tool 102 may, e.g., be a cut-off disc or a drill, such as a coredrill. lt is appreciated that the wireless identification tags, readers, and systemsdiscussed herein are applicable to a wide range of work tools, notjust rotatable work tools.

Figure 1 also shows a separate reader device 170 which may be in the formof, e.g., a smartphone, a tablet, or the like. The separate reader device 170may be used to interface with the wireless identification tag 110 to, e.g., readout data from the tag or to write data onto a tag memory. The separate readerdevice 170 may also be used to configure the wireless identification tag 110.

Figure 16 shows a work tool 1600 similar to the work tool in Figure 1. However,in Figure 16, the reader 120 is connected to a separate charging circuit 580configured to harvest energy from one or more permanent magnets 1610arranged on the work tool 102. The harvested energy may then be stored inan energy storage device 570 such as a rechargeable battery. The one or morepermanent magnets 1610 are arranged at a radial distance R' from a center ofrotation C of the work tool 102. The radial distance R' is preferably differentfrom the radial distance R so as to not interfere with the tag-reader inductiveconnection. However, the reader 120 may be arranged to detect passage ofthe one or more permanent magnets in order to, e.g., synchronize readeroperation. This is possible since there will be a fixed time duration between thepermanent magnets 1610 passing the reader 120 and the wireless tag 110passing the reader.

The reader 120 in Figure 16 is optionally arranged to communicate with acontrol unit 140 via wireless link 1620 by a radio frequency transceiver 590.The reader may also communicate with the remote server 150, and perhapsalso with the separate reader device 170 configured to read out data from thesystem. The separate reader device 170 may be comprised in, e.g., asmartphone, tablet or the like.

According to an example, a diameter Q of the wireless identification tag 110 isbetween 10-20 mm, and preferably about 15 mm. The radial length L of thereader 120 approximately mid-point as indicated in Figure 5 is between 50-100mm, and preferably about 80mm, corresponding to one radian at the mounted radial distance from the center C.

The wireless identification tag 110 and the wireless identification tag reader120 are comprised in a wireless identification tag system that enablesfunctions such as identifying the type of work tool 102 attached to theconstruction equipment 100, and gathering data about tool use in the tag,which data can then be wirelessly accessed by the reader 120, and fed, e.g.,to a control unit 140 in the construction equipment 100 or to a remote server150. Several different applications where the wireless identification tag system110, 120 can be used will be described below. For instance, sensors such asinertial measurement units (IMU), temperature sensors, shock sensors, andvibration sensors can be arranged in connection to the wireless identification tag 110, and data from these sensors can be accessed via the reader 120.

According to some aspects, the control unit 140 is communicatively coupled tothe remote server 150 via wireless link 151.

The remote server 150 may, e.g., be configured for fleet management of acollection of work tools 100. The remote server may keep inventory based onwireless identification tag 110 identifier data and monitor the tools in theinventory based on sensor output from the tags 110. A number of applicationsinvolving the wireless identification tag 110, 1410 the reader 120, 1420 and the remote server 150 will be discussed below. 11 Some RFID technologies use electromagnetic induction between two loopantennas located within each other's near field, effectively forming an air-coretransformer, for communication. Such systems often operate within theglobally available and unlicensed radio frequency ISM band around 13.56MHz. Theoretical working distance with compact standard antennas is up to20 cm but the practical working distance is about 10 cm. ln a passive mode ofoperation, an initiator device provides a carrier field and a target deviceanswers by modulating the existing field. ln this mode, the target device maydraw its operating power from the initiator-provided magnetic field, thuseffectively making the target device a transponder. The target devicecorresponds here to the wireless identification tag 110 and the initiator devicecorresponds to the wireless identification tag reader 120.

The present system 110, 120 may operate according to this electromagneticinduction principle of communication, thus, as the tag 110 passes under thereader 120, the two come into range of each other for a short time duration.The tag is the first powered up, drawing energy from the reader via theinductive coupling, and then modulates the field in order to transfer informationto the reader, such as an identification number or other data. This type ofcommunication is known in general and will therefore not be discussed in more detail herein. ln physics, specifically electromagnetism, the magnetic flux through a surfaceis the surface integral of the normal component of the magnetic flux passingthrough that surface. The SI unit of magnetic flux is the weber (Wb), and theCentimetre-Gram-Second (CGS) unit is the Maxwell. Magnetic flux is usuallymeasured with a known flux-meter, which contains measuring coils andelectronics, that evaluates the change of voltage in the measuring coils to calculate the measurement of time varying magnetic flux.

With reference to Figure 7A, RFID tags operating according to the inductionprinciple of communication described above is hampered, or quenched, bynearby electrically conductive surfaces 720. For a perfect electrical conductorwith a hole or aperture 700 enclosed by the surface 720, the total magnetic 12 flux through the hole will always be constant. This is a direct effect of the % a %Acdßlfßdsåt The closed line integral along the edge 710 of the aperture 700 will be zero Maxwell-Faraday equation: because there cannot exist an electric field in a perfect conductor. This meansthat the change in total flux through the hole over time also is zero. l.e., if themagnetic flux through the hole was zero at one point in time it will always be ZGFO.

Note in Figure 7A how (assuming a homogenous applied field) the normal component of the flux (É - el) is inverted close to the edge of the circular hole700. l.e. a tag 110 with a coil antenna along the very edge of the hole would Û _»-UB-e,ds=oa: However, a smaller coil centred in the hole would have a net flux which would have zero net flux. give an induced ï-field. This finding suggests that there is an optimum size ofthe tag antenna in relation to the diameter of the hole, as clearly the total flux goes towards zero when the surface area of the Tag S -> 0.

With reference to Figure 7A, consider now a magnetic flux inside the perimeter710 of the hole 700 that is inverted along the edge of the hole. lnside the holetwo open loops are placed, an inner loop denoted A and an outer loop denotedB.

Herein, in line with convention, a dot 701 represents a vector going outwardswhile a cross 702 represents a vector in the opposite direction, i.e., goinginwards. The dot schematically 701 shows an arrow approaching a viewerwhile the cross schematically illustrates an arrow 702 seen moving away from the viewer.

The voltage VA is the voltage induced in loop A and the voltage VB is thevoltage induced in loop B. Connecting the loops A and B in series so that VAB =2 VA = 2 VB both the inward and outward flux through the hole is used. lf more 13 inductance is required by the tag both loop A and loop B can be made with more than one turn and the same principle applies.

With reference to Figure 7B, the above described principle also applies to non-circular, and non-symmetric apertures formed in electrically conductivesurfaces. Figure 7B shows an irregular hole 750 defined by a hole boundary710. The magnetic flux has a first polarity, here shown as upwards in regions730a, 730b, and 730c, while the rest of the aperture 740 is associated with amagnetic flux of opposite polarity, here shown as downwards. lt is appreciated that voltage and potential are relative concepts which can bemeasured with respect to different reference frames. The concept of inducedvoltage and potential is known in general and will therefore not be discussed in more detail herein.

Figure 13A shows an example of magnetic flux 1310 through a hole in anelectrically conductive surface where an ordinary planar single coil antenna isused. lt is seen that the polarity of the flux changes close to the hole boundary.This magnetic flux 1310 is different from the magnetic flux 1320 shown inFigure 13B resulting from use of a wireless identification tag such as the tag 110 shown in Figures 2 and 3.

Figure 8 shows a layout 800 of inductive planar loops arranged matched to theregions of magnetic flux with positive and negative polarity. Thus, terminals810a and 810b generate a positive voltage VAB = VB -VA, where VA is thepotential at terminal 810a and VB is the potential at terminal 810b, due to theupwards magnetic flux time derivative in region 730a. ln the same way;terminals 830a and 830b generate a positive voltage between them due to theupwards magnetic flux time derivative in region 730b, and terminals 860a and860b generate a positive voltage between them due to the upwards magneticflux time derivative in region 730c. At the same time terminals 820a and 820b,terminals 850a and 850b, and terminals 850a and 850b generate a positivevoltage due to the downwards magnetic flux time derivative in region 730b.The different terminal pairs can be connected in series to increase overallvoltage, or in parallel to reduce source resistance. 14 The inductive planar loops exemplified in Figure 8 are all single turn. Figure 9illustrates an example 900 where one inductive planar loop is a multi-turn coilterminated by terminals 910a and 910b. A multi-turn coil may be realized as aflat spiral coil, a planar square spiral coil, a planar rectangular spiral coil, aplanar hexagonal spiral coil, or an octagonal spiral coil, just to give a fewexamples. Notably, 'planar' does not necessarily mean that the entire coil iscomprised in a plane. Rather, parts of the coil may, e.g., be arranged ondifferent layers of a printed circuit board or the like. Thus, 'planar' should beinterpreted broadly to mean any type of structure extending substantially in aplane, i.e., substantially flat, as opposed to having significant extensiondirections in more than two dimensions, i.e., having a volume in three dimensions.

The above described mechanisms can be exploited in order to provide animproved wireless identification tag system, as will now be described withreference to Figures 2-5.

Figure 2 shows an example wireless identification tag 110 for embedding intoan electrically conductive surface 101 of a rotatable work tool 102 such as the work tool shown in Figure 1.

The tag comprising at least a first 210 and a second 220 inductive planar loophaving respective first and second terminals 230, 240, 250. The inductiveplanar loops in the example of Figure 2 are connected in series and thereforeshare a common terminal 240. Thus, according to aspects, a terminal like theterminal 240 mayjust be a continuing wire that extends from a planar loop intoanother planar loop without interruption. The first loop 210 is directed in aclockwise direction 215. The second loop 220 is instead directed in acounterclockwise direction 225, i.e., in an opposite direction compared to thefirst loop. Thus, by connecting the loops by the common terminal 240, the twoloops become connected in series with respect to an induced voltage at the terminals of the loops.

The first inductive planar loop 210 and the second inductive planar loop 220 are arranged in relation to a common plane, e.g., parallel to the common plane.

Notably, connecting to the discussion above on regions with different magneticflux polarity, the first inductive planar loop 210 and the second inductive planarloop 220 are arranged to cover different areas of the common plane, whereeach area on the common plane is associated with a respective polarity of themagnetic flux normal to said plane. The plane referred to is here a planedefining a major extension of the flat wireless identification tag, which is coinedshaped in this example. According to an example, a diameter D of the wirelessidentification tag 110 is between 10-20 mm, and preferably about 15 mm.

The different areas may, according to some aspects, be separate areas.However, the areas may also be partly overlapping, which can be the case,e.g., if the inductive planar loops are formed on separate layers of a PCB.

Figure 4 shows the wireless identification tag 110 when embedded in a hole201 formed in an electrically conductive surface 101 of a rotatable work tool102. The tag is preferably comprised on a piece of printed circuit board (PCB),which can be glued into a hole formed in the work tool 102.

With reference to Figure 2, the wireless identification tag 110 comprisesprotruding portions 270 configured to engage slots formed in the work tool,thereby aligning the tag 110 with respect to the work tool 102. The wirelessidentification tag shown in Figure 2 is arranged to be embedded into the worktool 102 such that the separation line 260 forms a tangent to the circular arc130. The protruding portions simplify assembly of the work tool 102 and thetag 110.

According to other aspects, the protruding portions 270 are configured asdistance elements to space the tag 110 from the edge of the hole 201 formedin the work tool 102 to receive the tag 110. The distance elements then centerthe tag in the hole and allows for, e.g., glue to fill the gap between tag and hole boundary.

The tag 110 is symmetric in the sense that a symmetry line or separation line260 separates the first 210 and the second 220 inductive planar loops. Thisway, the first inductive planar loop 210 will be radially outside the circular arc130 when the tag rotates along with the work tool 102 in direction D, while the 16 second inductive planar loop 220 will be located radially inside the circular arc130. Notably, when the tag 110 passes under the reader 120, a center point280 ofthe tag follows along the circular arc 130 each revolution. ln other words,the areas are separable by a line 260 drawn on the common plane or by an arc of a circle having a radius R drawn on the common plane.

With reference to the discussion in connection to Figures 8-9, the tag 110 mayaccording to some aspects comprise three or more inductive planar loops, notonly two as shown in Figure 2. Each inductive planar loop is then arranged tocover a different or separate area of the common plane, where each area isassociated with a respective polarity, i.e., positive or negative, of the magneticflux normal to said plane. lt is appreciated that there are only two possiblepolarisations of the flux normal to a plane, namely positive and negative.

The tag 110 shown in Figure 2 has single turn inductive planar loops.According to some aspects, at least one of the first inductive planar loop 210and the second inductive planar loop 220 is a single turn inductive planar loop.However, one or more of the loops may also be a multiple turn inductive planarloop. An example ofa wireless identification tag 110 with multiple turn indictiveplanar loops is shown in Figure 3. The first loop 210 and the second 220 planarloops are multiple turn inductive planar loops arranged serially connected and in a common plane.

The two loops comprising multiple turns provide a coupling with increasedinduced voltage at the terminals of the tag with respect to the reader 120. lnFigure 3, the inductive planar loops are constructed by a sequence of half-moon shaped turns starting from a terminal 230, 250. The two loops are seriallyconnected, although the connecting or common terminal corresponding to theterminal 240 in Figure 2 is not shown in Figure 3. The first loop 210 is directedin a counterclockwise direction. The second loop 220 is instead directed in aclockwise direction, i.e., in an opposite direction compared to the first loop.

As noted above, the wireless identification tags shown in Figures 2 and 3 areboth arranged to be embedded into the work tool 102 such that the separationline 260 form a tangent to the circular arc 130. 17 Figure 5 shows a wireless identification tag reader 120 for reading data fromthe wireless identification tag 110, also when the tag is embedded into anelectrically conductive surface 101 of a rotatabie work tool 102, the readercomprises at least a first 510 and a second 520 inductive planar loop inducinga current distribution in the surface of the rotatabie work tool 102 whichtogether with the current distribution in loop 510 and loop 520 is associatedwith a magnetic flux through the hole 201 shown, e.g., in Figure 4, matched torespective first 210 and second 220 inductive planar loops on the tag 110.Each loop 510, 520 on the reader 120 has a corresponding first and secondterminal 530, 540, 550, wherein the first loop 510 is arranged to generate amagnetic flux having a first flux polarity, wherein the second loop 520 isarranged to generate a magnetic flux having a second flux polarity different oropposite from the first flux polarity.

According to aspects, the first 510 and the second 520 inductive planar loophave arcuate forms corresponding to circle arcs of circles with a first and asecond radius associated with the rotatabie work tool 102. The length L of thearcs may be configured in dependence of the rotational speed of the work tool102, and the time required to perform wake up and communication operationsas the tag 110 passes the reader 120. According to an example, the length Lis between 50-100 mm, and preferably about 80 mm.

There is also disclosed herein a wireless identification tag reader 120 forreading data from a wireless identification tag 110 embedded into anelectrically conductive surface 101 of a rotatabie work tool 102. The readercomprises at least one loop, of which one loop segment is positioned over aline 560 defining separation of areas with flux of opposite polarities matchingthe separation line 260 between areas of opposite flux polarities of the wirelessidentification tag loops.

With reference to Figure 1, there is furthermore disclosed herein a blade guard103 for a work tool 100 comprising a rotatabie work tool 102, wherein the bladeguard 103 comprises a wireless identification tag reader according to the above discussion. 18 The tag 110 and the reader 120 together form a wireless identification tagsystem 110, 120 comprising a wireless identification tag 110 and a wirelessidentification tag reader 120 for reading data from the wireless identificationtag 110 when embedded into an electrically conductive surface 101 of arotatabie work tool 102, the reader 120 comprising at least one inductive planarloop 510, 520, of which at least one loop segment is positioned over a line 560defining separation of areas with magnetic flux of opposite polarities matchinga separation line 260 between areas of opposite flux polarities of inductive planar loops on the wireless identification tag.

Herein, a serial connection of two or more inductive planar loops or coils is aconnection which increases overall voltage, i.e., a connection between positiveand respective negative voltage terminals. lt is appreciated that the relativeterms positive voltage and negative voltage are defined in dependence of thedirection of magnetic flux' time derivative through the inductive planar loop.ldeally, for a serial connection, the voltage induced over the new (combined)two ports of the combined loops is the sum of the voltage induced over eachof the individual loops. However, losses may be incurred resulting in acombined voltage somewhat below the sum of the voltage induced over eachof the individual loops. ln some implementations of systems such as this, acapacitance is used to make the coil and capacitance circuit resonant whichproduces an even higher voltage. The capacitance can also in some systemsbe in series with the inductance of the antenna and then the voltage atresonance will be very low but the current high. Such implementations are known and will therefore not be discussed in more detail herein.

A parallel connection of two inductive planar loops is the opposite to a serialconnection. lf the serial connection connects positive terminal to negativeterminal, the parallel connection connects positive to positive, or negative tonegative. lt is again appreciated that the relative terms positive voltage andnegative voltage are defined in dependence of the direction of magnetic flux'time derivative through the inductive planar loop. ldeally, for a serialconnection, the voltage induced over the new (combined) two ports of the 19 combined loops is the same as the voltage induced over each of the individualloops if the voltages of the two loops are identical.

According to some aspects, the wireless identification tag 110 comprises aconnecting network 240 configured to serially connect the first 210 and thesecond 220 inductive planar loops, thereby increasing a total voltage inducedby the first 210 and the second 220 inductive planar loop in response to changes in a magnetic flux.

According to some other aspects, the wireless identification tag 110 comprisesa connecting network 240 configured to connect the first 210 and the second220 inductive planar loops in parallel, thereby reducing source resistanceassociated with the wireless identification tag 110. Source resistance is hereto be interpreted in relation to the resistive element of a circuit equivalentcomprising of the series connection of a Thevenin equivalent and a reactance,that electrically describes the power delivered by the planar inductive loops210 and 220 into a load impedance when the loops are subjected to a time varying magnetic flux.

The connecting network 240 may, e.g., be just a common terminal such as inFigure 2. However, the terminals of one or more inductive planar loops mayalso be connected to ports on a switch circuit comprising a connecting matrix.This connecting matrix may be arranged to permanently connect terminals ina pattern, or it can be arranged to connect terminals according to some inputcontrol signal. This way the connections between loops may be switched froma serial connection into a parallel connection depending on the control signal.

The wireless identification tag 110 may, according to some aspects, comprisean identification circuit 1000 connected to the first inductive planar loop 210and to the second inductive planar loop 220, wherein the identification circuit1000 is arranged to modulate a load on the terminals of the first inductiveplanar loop 210 and on the second inductive planar loop 220, thereby providingan inductive communication channel to a wireless identification tag reader 120.lnductive communication channels were discussed above. Such channels and methods of communication are known in general and will not be discussed in more detail herein. One example identification circuit 1000 will be discussedbelow in connection to Figure 10. The identification circuit 1000 may comprise,e.g., processing circuitry, storage medium 1030, and an interface forcommunications 1020. The interface communicates via the inductive planarloops with the reader 120 by modu|ating a load on the terminals of the firstinductive planar loop 210 and on the second inductive planar loop 220. Thereare also low frequency RFID protocols which do not use load modulation butinstead has a charging time and then actively transmits once the RFID circuit has enough energy to do so.

According to some aspects, the identification circuit 1000 is arranged to bepowered via the first 210 and second 220 inductive planar loops. Thus, as thewireless identification tag passes in vicinity of the reader, it draws energy fromthe reader which allows it to power up and start operating. Any surplus energymay be stored by a capacitor, battery, or other means for storing electrical energy.

According to some aspects, the identification circuit 1000 is arranged to storeidentification data. The identification data may, e.g., comprise an identificationcode or number which can be used to identify the type of object which the tagis attached to, or its owner. The identification data may furthermore comprise data to identify a production batch, a producer, a classification or the like.

The identification data may also store dimension data such as a rotatable work tool diameter and thickness.

The identification data may furthermore comprise data relating to intended use, i.e., an operational design regime of the tool and other tool specifications.

The dimension data and data relating to intended use may support applications that prevent erroneous use of the construction equipment.

The identification data may also comprise data relating to an owner of the tool, optionally in combination with authentication data. 21 The authentication data and data relating to the owner of the tool can be usedto prevent unauthorized use of the construction equipment and/or of therotatable work tool 102.

The identification circuit 1000 may furthermore be equipped or connected tovarious forms of sensors or actuators. For instance, a temperature sensor,arranged to determine a temperature value associated with the work tool 102,may be configured to periodically sample a temperature value associated withthe work tool 102, and store the data, or some function of the data such asmaximum temperature, in the storage medium 1030. The reader 120 can thenbe used to access the stored temperature data in order to monitor, e.g., if thework tool 102 has been subject to overheating. Temperature data in the formof temperature signatures can also be used to detect when the work tools hasbeen worn out and needs replacement. The identification circuit 1000 can beconfigured to perform such detection based on the temperature data andtrigger transmission of a warning signal via the reader 120.

According to other aspects, the identification circuit 1000 can be arranged todetermine an acceleration value, e.g., by means of an inertial measurementunit (IMU) integrated with or connected to the identification circuit. The IMUcan be configured to determine an engine speed, e.g., a rotational velocity interms of revolutions per minute (RPM). This data can again be read out via thereader by, e.g., the control unit 140. By comparing the RPM from the IMU withthe RPM from the engine control system, need for drive belt adjustment, drivebelt wear and the like can be determined. lt is also possible to determine thetype of material being cut by analysis of the vibrations measured by the IMU.ln case the work tool 102 is used to cut into a material for which it was notintended, a warning signal can be issued. Other forces and vibrations actingon the tool can also be determined and stored for later access. This wayanalysis can be performed on a tool to see if the tool has been subject to unusually large forces or vibrations, or mechanical impact. 22 A kickback condition can be detected by the IMU on the identification circuit1000 and the event can be stored in memory. The kickback data can then formbasis for further analysis.

A pre-kickback condition can also be detected by the IMU on the identificationcircuit 1000. A pre-kickback condition is a jerking motion by the tool which oftenoccurs prior to kickback. The pre-kickback condition often occurs when therotatable work tool 102 is subject to wear.

Erroneously assembled work tools give rise to vibrations which can bedetected. A warning signal may be triggered in case the vibrations match some pre-determined vibration criteria.

According to some other aspects, the identification circuit 1000 is arranged toreceive data from the wireless identification tag reader 120, and to store thedata in a memory unit. This enables, e.g., the reader 120, or a control unit 140connected to the reader 120, to measure operating time for a given tool, andto update an operating time parameter of the tool. A user can then read outthe operating time parameter and thereby obtain information about how long agiven tool has been used. For this purpose, a separate reader device 170 maybe provided. This separate reader device 170 is arranged to interface with thewireless identification tag 110, to power the tag, and to read out data from thetag 110.

The reader 120 and/or control unit 140 may also determine one or moreoperating conditions and store this information in the tool, by the identificationcircuit. The operating conditions may, e.g., comprise a user identity orauthorization code, a time ofday, a day of the week, and the like. The separatereader device 170 can then be used to determine who has used a given tool,when, and for how long.

To summarize, with reference also to Figure 1, the construction equipment 100is arranged to obtain data from the wireless identification tag 110 via the reader120, and to take action in response to the obtained data, wherein the actioncomprises any of; adjusting one or more operation parameters of the 23 construction equipment, triggering an emergency routine or warning signal, and executing an authentication procedure.

Figure 6 is a flow chart illustrating methods as disclosed herein. Thesemethods comprise measuring data S1 by one or more sensor units arrangedin connection to the wireless identification tag, on the work tool 102. The datais then optionally pre-processed by the identification circuit 1000, before beingread out S2 by the reader 120 as the tag passes in vicinity of the reader 120.The methods also comprise processing the data by the control unit 140. Some examples of the illustrated methods have been discussed above.

The methods may also comprise reading data from the tag 110 by the separatereader device 170 discussed above.

With reference again to Figure 1, which shows construction equipment 100comprising a work tool 102. The work tool 102 in turn comprises an embeddedwireless identification tag 110 according to the discussions above. Thewireless identification tag 110 is configured to rotate about a center of rotationC during operation of the work tool.

Some types of construction equipment are very sensitive to imbalance in thework tool. A cut-off disc for instance may start to wobble and cause reducedcomfort for the user in case the rotatable work tool is not correctly balanced.The hole formed in the work tool for embedding the wireless identification tag110 will cause a slight shift in the balance of the tool, since the tag is likely ofless weight than the material which has been removed. To compensate for thisshift of mass, the work tool 102 may optionally comprise a balancing holeconfigured to compensate for a weight imbalance in the rotatable work tool 102due to the embedded wireless identification tag 110. The balancing hole orholes may be arranged on opposite side of the work tool compared to thewireless identification tag, i.e., on the other side of the tool with respect to thecenter of rotation C. One or more balancing holes may be formed in the worktool 102. Alternatively, or in combination with the balancing holes, extraweights may be arranged on the work tool to balance the tool in compensationof the wireless identification tag 110. 24 According to some aspects, the work tool 102 comprises one or moreembedded permanent magnets 160 configured in radial dependence of theembedded wireless identification tag 110. A magnet 160 may, for instance, bearranged in a balancing hole. These magnets may be used to wake up thereader, i.e., they may be arranged in front of the wireless identification tag inthe rotation direction D. When they pass the reader, the reader knows the tag110 soon follows, and it can therefore power up its systems. The reader canthen go to sleep after the tag has passed, until the magnet passes again. Thisway the reader may conserve energy, by implementing a type of duty-cycleoperation.

According to some aspects, with reference to Figures 1, 5 and 16, thewireless identification tag reader 120 comprises an energy storage device 570and a charging circuit 580 arranged to harvest energy from one or morepermanent magnets 160, 1610 attached to the rotatable work tool 102. Thewireless identification tag reader 120 may then be at least partly powered bythe energy storage device 570.

This way the reader can be energy self-supportive in that it harvests energyfrom the time varying magnetic flux of the permanent magnet 160 which rotatesto pass the reader periodically.

According to some related aspects, the wireless identification tag reader 120comprises a radio frequency transceiver 590 configured to transmit the datafrom the wireless identification tag 110 to an external entity such as the controlunit 140 and/or the remote server 150. This way the need for a wiredconnection to, e.g., the control unit 140 is avoided, which is an advantage. An example of this type of tag will be discussed below in connection to Figure 14. lt is appreciated that the permanent magnet 160 may have at least two differentpurposes, i.e., energy harvesting and circuit wake-up. One or more permanentmagnets may be arranged on the rotatable work tool 102. For energyharvesting purposes, it may be advantageous to embed an array of permanentmagnets with alternating polarity in order to provide an increased time varyingmagnetic flux experienced by the reader 120. Thus, there is disclosed herein a rotatable work tool 102 comprising one or more embedded permanentmagnets 160 configured to power and/or wake up a wireless identification tagreader 120. An array of permanent magnets is preferably arranged along acircular arc with alternating polarity in order to optimize energy harvestingcapability.

With reference to Figure 12, according to some aspects, the work tool 102 alsocomprises a wire 1200 extending in a loop radially outwards on the rotatablework tool 102 from the embedded wireless identification tag 110. Theembedded wireless identification tag 110 is arranged to detect tool wear incase the wire loop is broken. Thus, if an abrasive portion or cutting segment1210 of the work tool 102 is worn down, the wire gets cut, which the tag 110can detect, e.g., by detecting the resulting open circuit. The tag 110 can thentrigger a warning signal which the control unit 140 can receive via the reader120.

Several applications may be realized by the herein disclosed identificationtags, readers, and systems. These applications will now be discussed in detail.lt is appreciated that the applications may be implemented separately or incombination. The applications are based on construction equipment 100comprising a rotatable work tool 102, a wireless identification tag reader 120,and a control unit 140. The applications are also possible to realize based onthe wireless identification tag 1410 and construction equipment discussedbelow in connection to Figures 14 and 16. The rotatable work tool 102comprises a wireless identification tag 110, 1410 according to the abovediscussion, i.e., the tag is configured to store data configured to be accessiblevia the wireless identification tag reader 120 or via radio link to the control unit140 as discussed below in connection to Figures 14, 15 and 16. ln some applications, as noted above, the data configured to be accessible viathe reader 120 or by radio frequency link 1430 comprises identification data toidentify the rotatable work tool 102. This allows for keeping track of therotatable work tool 102 by, e.g., defining a digital twin associated with therotatable work tool. For instance, the digital twin may comprise data related to 26 tool specification, intended use domain, dimensions, and the like. The digital twin may also comprise information associated with an owner of the tool. ln some other applications, the data configured to be accessible via the reader120 or by radio frequency link 1430 comprises authentication data toauthenticate the rotatable work tool 102 against the control unit 140. Theauthentication data can be used to, e.g., ensure that only the intended tool ispossible to use with a given piece of construction equipment. ln case someother tool is attached to the equipment, the equipment can be prevented fromoperating by, e.g., disabling the power source or the like. A rental company,fleet operator, or the like, can thereby assure that a machine is only operated with certain rotatable work tools 102.

The data configured to be accessible via the reader 120 or by radio frequencylink 1430 optionally also comprises tool specification data associated with therotatable work tool 102. This way a given machine can be pre-configured toonly accept tools complying with some range of specifications. For instance, amachine may only be possible to start if the specification of the rotatable worktool meets some pre-determined criteria. lf the rotatable work tool does notmeet the criteria, operation can be prevented and/or a warning signal can betriggered.

The data configured to be accessible via the reader 120 or by radio frequencylink 1430 may also comprise tool dimension data associated with the rotatablework tool 102. A machine can be configured to only accept tools having certainpre-defined dimensions. lf a tool not complying the requirements on dimensionis attached to a given piece of construction equipment, operation can beprevented, or a warning signal can be triggered. This also applies to theinterface between tool and machine. lf the two are not in compliance, operation can be prevented and/or a warning signal triggered.

The wireless identification tag 110, 1410 optionally comprises a temperaturesensor arranged to determine and to store a temperature value associated withthe rotatable work tool 102. This allows the construction equipment to monitortool temperature and thereby, e.g., prevent tool overheating. lf the reported 27 temperature from the wireless identification tag goes above a predeterminedthreshold level, then the machine can be stopped, a warning signal can betriggered, or the rotational velocity decreased. Cooling water flow can also becontrolled in dependence of the reported tool temperature, i.e., theconstruction equipment 100 is optionally arranged to regulate a flow of waterfor cooling the rotatable work tool 102 based on a temperature sensor readingfrom the wireless identification tag 110.

The wireless identification tag 110, 1410 may further comprise a first and asecond temperature sensor, arranged radially from each other on the rotatablework tool 102, wherein the first and second temperature sensor is arranged todetermine a radial temperature gradient associated with the rotatable work tool102. This way a more refined control based on tool temperature is enabled. Byknowing the temperature gradient and the radial location R of the tag, atemperature on the perimeter of the tool, close to abrasive or cutting elements,can be determined by extrapolating the temperature gradient from the locationof the tag.

As noted above, the reader 120 and/or control unit 140 may store data in thetag comprising information related to who has used the tool, when, and for howlong. This data can then be used for setting service intervals and determiningwhen a rotatable work tool 102 should be replaced. lt may be advantageousto let the reader 120 and/or the control unit 140 measure operating time, sincethe wireless identification tag 110 may be sleeping for large portions of theoperating time, and can therefore not easily measure time by, e.g., a timer ora clock.

Nevertheless, the wireless identification tag 110, 1410 optionally comprises atimer or clock configured to determine and to store an operating timeassociated with the rotatable work tool 102. This allows the control unit and/orthe remote server 150 to monitor how long a tool is used. This data can thenbe used for setting service intervals and determining when a rotatable work tool 102 should be replaced. 28 The wireless identification tag 110, 1410 optionally comprises an inertialmeasurement unit (IMU). lMUs were discussed above. The IMU may beconfigured to monitor a vibration signature of the rotatable work tool 102, andto detect any of; crack formation in the tool, blade core skew or unevenness,blade wear, and tool glazing or occurrence of polished diamonds, based onthe vibration signature.

A vibration signature is a time sequence of vibration which can be used toidentify various conditions. For instance, crack formation in the rotatable worktool gives rise to a characteristic vibration pattern which can be detected bythe IMU by comparing the measured vibration to a set of pre-defined vibrationpatterns in terms of, e.g., waveform shape of frequency characteristics. Bladecore skew or unevenness, blade wear, and tool glazing or occurrence ofpolished diamonds also give rise to characteristic vibration patterns orsignatures which can be detected by the IMU. The detection may be based onan artificial neural network trained to recognize various types of vibration signatures.

Other applications comprise the IMU being configured to monitor rotatablework tool 102 jerk, and to detect a kickback condition and/or a pre kickbackcondition based on the monitored tool jerk. Kickback conditions are associatedwith rapid acceleration in certain directions. Kickback is often preceded by oneor more pre-kickback events, which are minor kickbacks orjerking motions bythe tool. An IMU can be trained by, e.g., artificial neural network or otherwiseconfigured to recognize such pre-kickback events and to trigger a warningsignal or even prevent further use of the tool until it has been serviced, e.g., by replacement or re-tipping of the rotatable work tool 102.

Some more advanced applications are built on a construction equipmentsystem 100, 150 comprising the construction equipment 100 discussed hereinand the remote server 150. The remote server 150 is communicatively coupled151 with the control unit 140 and configured to access data stored by thewireless identification tag 110, 1410. 29 ln some such applications the remote server 150 and/or the control unit 140 isarranged to determine a cost per use associated with the constructionequipment 100. The cost per use can be determined based on, e.g., estimatedtool wear, tool use time, and on how the tool has been used, e.g., if challengingmaterials have been processed by the tool or if the tool has been used underlighter load only. ln some other applications the remote server 150 is arranged to storeinformation relating to the construction equipment 100 and/or relating to therotatable work tool 102, wherein the information is indexable by identificationdata stored by the wireless identification tag 110. This allows, e.g., a fleetoperator to keep track of inventory by managing a set of digital twinscorresponding to the work tools. The digital twins can be used to keep track of tool use, tool wear, and to determine appropriate service intervals.

The remote server 150 can also be arranged to determine a service intervalassociated with the construction equipment 100 and/or trigger rotatable worktool 102 replacement based on the data stored by the wireless identificationtag110, 1410.

Some applications comprise the remote server 150 being arranged todetermine one or more statistics associated with the construction equipment100 and/or with the rotatable work tool 102. These statistics can be used by afleet operator or by a tool manufacturer for analysis and optimization of overalloperations. The statistics can also be used as feedback for design of new toolsand updates to existing products.

Some of the data reported from the wireless identification tag may be indicativeof tool misuse by an operator. For instance, some operator or group ofoperators may experience increased occurrences of kickback conditions, orincreased tool wear. This misuse can be detected, and training needsidentified. Training can then be offered to identified operators or groups ofoperators. ln other words, the remote server 150 is optionally arranged todetermine a training need of an operator using the construction equipmentbased on the data stored by the wireless identification tag 110, 1410.

Figure 10 schematically illustrates, in terms ofa number of functional units, thegeneral components of a control unit 140, or an identification circuit 1000, atag 110 or a reader 120 according to embodiments of the discussions herein.Processing circuitry 1010 is provided using any combination of one or more ofa suitable central processing unit CPU, multiprocessor, microcontroller, digitalsignal processor DSP, etc., capable of executing software instructions storedin a computer program product, e.g. in the form of a storage medium 1030.The processing circuitry 1010 may further be provided as at least oneapplication specific integrated circuit ASIC, or field programmable gate arrayFPGA.

Particularly, the processing circuitry 1010 is configured to cause the device110, 120, 140, 1000 to perform a set of operations, or steps, such as themethods discussed in connection to Figure 6 and the discussions above. Forexample, the storage medium 1030 may store the set of operations, and theprocessing circuitry 1010 may be configured to retrieve the set of operationsfrom the storage medium 1030 to cause the device to perform the set ofoperations. The set of operations may be provided as a set of executableinstructions. Thus, the processing circuitry 1010 is thereby arranged to executemethods as herein disclosed.

The storage medium 1030 may also comprise persistent storage, which, forexample, can be any single one or combination of magnetic memory, opticalmemory, solid state memory or even remotely mounted memory.

The device 110, 120, 140, 1000 may further comprise an interface 1020 forcommunications with at least one external device. As such the interface 1020may comprise one or more transmitters and receivers, comprising analogueand digital components and a suitable number of ports for wireline or wirelesscommunication.

The processing circuitry 1010 controls the general operation of the device 110,120, 140, 1000, e.g., by sending data and control signals to the interface 1020and the storage medium 1030, by receiving data and reports from the interface1020, and by retrieving data and instructions from the storage medium 1030.ln case of a tag or a reader, the interface comprises (or is connected via ports) 31 to the inductive planar loops of either the tag 110 or the reader 120. Othercomponents, as well as the related functionality, of the control node are omittedin order not to obscure the concepts presented herein.

Figure 11 illustrates a computer readable medium 1110 carrying a computerprogram comprising program code means 1120 for performing the methodsi||ustrated in Figure 6, when said program product is run on a computer. Thecomputer readable medium and the code means may together form acomputer program product 1100.

Figure 14 shows construction equipment 1400 where a wireless identificationtag 1410 has been embedded into the rotatable work too 102. However, thiswireless identification tag comprises an inductive loop configured to harvestenergy from a time varying magnetic flux generated by one or more permanentmagnets 1420 arranged on the blade guard 103 of the construction equipment1400. The wireless identification tag 1410 further comprises energy storagemeans and a radio frequency transceiver, by which it can communicate viawireless link 1430 with the control unit 140. Thus, the applications discussedabove are possible to realize without a reader arranged in connection to theblade guard 103, such as the reader 120 shown in Figure 1. The identificationcircuit 1000 discussed above can be used together with the wirelessidentification tag 1410 without modification, or with minor modifications.

According to an example, a diameter D of the wireless identification tag 1410is between 10-40 mm, and preferably about 25 mm.

Figure 14 shows a blade guard 103 comprising one or more permanentmagnets 1420 arranged to power a wireless identification tag 1410 arrangedembedded in a rotatable work tool 102. lt is appreciated that, although Figure14 shows three magnets, any number of permanent magnets can be used, including a single permanent magnet.

Figure 14 also shows a construction equipment 1400 comprising a wirelessidentification tag 1410, a blade guard 103 with one or more permanentmagnets 1420, and a control unit 140 arranged to communicate with thewireless identification tag 1410 via radio link 1430. 32 Figure 15 schematically illustrates a wireless identification tag 1410 forembedding into a rotatable work tool 102. The tag comprises at least a firstinductive loop 1510, an energy storage device 1520, processing circuitry 1530,and a radio frequency transceiver 1540. The wireless identification tag 1410 isarranged to harvest electrical energy from a time varying magnetic flux by thefirst inductive planar loop 1510 and to store the electrical energy in the energystorage device 1520. The processing circuitry 1530 and the radio frequencytransceiver 1540 are arranged to be powered by the energy storage device1520.

The control unit 140 is communicatively coupled 151 to the remote server 150 as discussed above.

Figure 16 shows a work tool 1600 similar to the work tool in Figure 1. However,in Figure 16, the reader 120 is connected to a separate charging circuit 580configured to harvest energy from one or more permanent magnets 1610arranged on the work tool 102. The harvested energy may then be stored inan energy storage device 570 such as a rechargeable battery or capacitor.The one or more permanent magnets 1610 are arranged at a radial distanceR' from a center of rotation C of the work tool 102. The radial distance R' ispreferably different from the radial distance R so as to not interfere with thetag-reader inductive connection. However, the reader 120 may be arranged todetect passage of the one or more permanent magnets in order to synchronizeoperation. This is possible since there will be a fixed time duration between thepermanent magnets 1610 passing the reader 120 and the wireless tag 110 passing the reader.

Claims (18)

1. Construction equipment (100, 1600) comprising a rotatable work tool(102), a wireless identification tag reader (120), and a control unit (140),wherein the rotatable work tool (102) comprises a wireless identification tag(110) configured to store data configured to be accessible via the wirelessidentification tag reader (120).

2. The construction equipment (100, 1600) according to claim 1, whereinthe data configured to be accessible via the reader (120) comprises identification data to identify the rotatable work tool (102).

3. The construction equipment (100, 1600) according to any previous claim,wherein the data configured to be accessible via the reader (120) comprisesauthentication data to authenticate the rotatable work tool (102) against thecontrol unit (140).

4. The construction equipment (100, 1600) according any previous claim,wherein the data configured to be accessible via the reader (120) comprisestool specification data associated with the rotatable work tool (102).

5. The construction equipment (100, 1600) according to any previous claim,wherein the data configured to be accessible via the reader (120) comprisestool dimension data associated with the rotatable work tool (102).

6. The construction equipment (100, 1600) according to any previous claim,wherein the wireless identification tag (110) comprises a temperature sensorarranged to determine and to store a temperature value associated with therotatable work tool (102).

7. The construction equipment (100, 1600) according to any previousclaim, wherein the wireless identification tag (110) comprises a first and asecond temperature sensor, arranged radially from each other on the rotatablework tool (102), wherein the first and second temperature sensor is arrangedto determine a radial temperature gradient associated with the rotatable worktool (102). 34

8. The construction equipment (100, 1600) to any previous claim, arrangedto regulate a flow of water for cooling the rotatable work tool (102) based on atemperature sensor reading from the wireless identification tag (110).

9. The construction equipment (100, 1600) according to any previous claim,wherein the wireless identification tag (110) and/or the wireless identificationtag reader (120) comprises a timer or clock configured to determine and tostore an operating time associated with the rotatable work tool (102).

10. The construction equipment (100, 1600) according to any previous claim, wherein the wireless identification tag (110) comprises an inertialmeasurement unit, IMU, wherein the IMU is configured to monitor a vibrationsignature of the rotatable work tool (102), and to detect any of; crack formationin the tool, blade core skew or unevenness, blade wear, and tool glazing or polished diamonds, based on the vibration signature.

11. The construction equipment (100, 1600) according to any previous claim, wherein the wireless identification tag (110) comprises an inertialmeasurement unit, IMU, wherein the IMU is configured to monitor rotatablework tool (102) jerk, and to detect a kickback condition and/or a pre kickback condition based on the monitored tool jerk.

12. The construction equipment (100, 1600) according to any previous claim,wherein the wireless identification tag (110) comprises a control unit (140) andan inertial measurement unit, IMU, wherein the IMU is configured to determinea rotational velocity of the work tool, wherein the control unit (140) is arrangedto detect a need for drive belt adjustment or drive belt replacement bycomparing the determined rotational velocity of the work tool to a velocity of an engine or power source arranged to drive the work tool.

13. A construction equipment system (100, 150) comprising the constructionequipment (100) according to any of claims 1-12, and a remote server 150,wherein the remote server (150) is communicatively coupled to the control unit(140) and configured to access data stored by the wireless identification tag(110).

14. The construction equipment system (100, 150) according to claim 13,wherein the remote server (150) and/or the control unit (140) is arranged to determine a cost per use associated with the construction equipment (100).

15. The construction equipment system (100, 150) according to claim 13 or14, wherein the remote server (150) is arranged to store information relatingto the construction equipment (100) and/or relating to the rotatable work tool(102), wherein the information is indexable by identification data stored by the wireless identification tag (110).

16. The construction equipment system (100, 150) according to any of c|aims13-15, wherein the remote server (150) is arranged to determine one or morestatistics associated with the construction equipment (100) and/or with therotatable work tool (102).

17. The construction equipment system (100, 150) according to any of c|aimsclaim 13-16, wherein the remote server (150) is arranged to determine atraining need of an operator using the construction equipment based on thedata stored by the wireless identification tag (110).

18. The construction equipment system (100, 150) according to any of c|aimsclaim 13-17, wherein the remote server (150) is arranged to determine aservice interval associated with the construction equipment (100) and/ortrigger rotatable work tool (102) replacement based on the data stored by the wireless identification tag (110).