WO2020239205A1

WO2020239205A1 - A computer implemented method for tracking work tools on a work site

Info

Publication number: WO2020239205A1
Application number: PCT/EP2019/063839
Authority: WO
Inventors: Calle SKILLSÄTER; Andreas NORRMAN
Original assignee: Volvo Construction Equipment Ab
Priority date: 2019-05-28
Filing date: 2019-05-28
Publication date: 2020-12-03

Abstract

The invention relates to a computer implemented method for tracking work tools on a work site, the method comprising the steps of: determining that a work tool is connected to a vehicle in the form of a working machine; identifying the type of the work tool being connected to the vehicle; receiving a state signal indicative of the work tool being disconnected, or has been disconnected, from the vehicle; determining the geographical position at which the work tool becomes or became disconnected from the vehicle; and - transmitting data comprising information on the type of work tool and said geographical position to one or more control units, wherein the transmitted data enables subsequent guiding of the vehicle or another vehicle to the geographical position for connecting the work tool.The invention may also be used for estimating wear of the work tool.

Description

A computer implemented method for tracking work tools on a work site.

TECHNICAL FIELD

The invention relates to a computer implemented method for tracking work tools on a work site. The invention also relates to a computer program, a computer readable medium a control unit, a system and a vehicle.

The invention is applicable on vehicles in the form of working machines within the fields of industrial construction machines or construction equipment, in particular wheel loaders. Although the invention will be described with respect to a wheel loader, the invention is not restricted to this particular machine, but may also be used in other working machines such as articulated haulers, excavators, forwarders and backhoe loaders.

BACKGROUND

Working machines in the form of articulated haulers, wheel loaders, trucks, forwarders and dumpers are frequently used for loading and transporting of material loads at construction sites, in forestry and the like. A load-receiving container of a hauler or dump truck may for instance be loaded with unprocessed material, such as rock fragments, at a loading location, transport the material to another location and dump the material (in)to a material processing device, such as into a buffering feeder of a crusher arranged to crush the rock fragments into smaller fragments.

Some working machines can be used for numerous different working operations. To this end, different interchangeable attachments or work tools may be connected to such working machines. For instance, for certain working operations a bucket may be connected to a wheel loader, and for other working operations the bucket is disconnected and instead a fork may be connected to the wheel loader.

For a large work site or for a work site with limited visibility/overview it may be a challenge to quickly find a work tool that has been disconnected in an earlier working operation and that is again needed for a new working operation. Furthermore, in some cases there may be a plurality of working machines at the work site, and a first working machine may, for instance, need to use a work tool which had previously been used and left somewhere by a second working machine.

US 9,938,693 B1 discloses a tracking system for a work tool. The tracking system includes a tracking device coupled to the work tool. The tracking system also includes an accelerometer coupled to the work tool. When the work tool is picked up by a working machine, the accelerometer activates the tracking device such that the tracking device communicates with a machine control module located on the working machine. Thus, on a work site each work tool must be equipped with a tracking device as well as an accelerometer operatively connected to the tracking device.

It would be desirable provide a simpler tracking solution, which facilitates for a working machine (or the driver of the working machine) to find a work tool that has earlier been left somewhere by the same or a different working machine.

SUMMARY

An object of the invention is to provide a method, a computer program, a computer readable medium, a control unit and a system, which can be used for providing a simple tracking of a work tool on a work site.

According to a first aspect of the invention, the object is achieved by a computer implemented method for tracking work tools on a work site, in accordance with claim 1. The method comprises the steps of:

- determining, by a processing circuitry, that a work tool is connected to a vehicle in the form of a working machine;

- identifying, using the processing circuitry, the type of the work tool being connected to the vehicle;

- receiving, at the processing circuitry, a state signal indicative of the work tool being disconnected, or has been disconnected, from the vehicle;

- determining, using the processing circuitry, the geographical position at which the work tool becomes or became disconnected from the vehicle; and

- transmitting, from the processing circuitry, data comprising information on the type of work tool and said geographical position to one or more control units, wherein the transmitted data enables subsequent guiding of the vehicle or another vehicle to the geographical position for connecting the work tool. By the provision of a method which tracks the work tool based on the act of disconnecting the work tool from the working machine, a simple solution is provided. There is thus no need to provide a relatively complicated tracking device (e.g. including an accelerometer) on the work tool as such and continuously sending tracking signals when the working machine moves around with the attached work tool. Instead, the inventive tracking can be activated at the time when needed, i.e. when the work tool is no longer operationally connected to the working machine. A further advantage is that since there is no need for continuous tracking as long as the work tool is connected to the working machine, the data traffic (amount of transmitted data) can be kept lower than in the prior art.

The expression“processing circuitry” as used above should be understood to include any type of computing device, such as an ASIC, a micro-processor, etc. It should also be understood that the actual implementation of such a processing circuitry may be divided between more than a single device/circuit. For instance, one device/circuit of the processing circuitry may identify the type of work tool, while another device/circuit of the processing circuitry may receive the state signal, and a third device/circuit of the processing circuitry may determine the geographical position. The transmitting of data may also be divided such that different devices/circuits of the processing circuitry transmit data comprising information on the type of work tool and data comprising information on the geographical position, respectively. Of course, it is also conceivable the processing circuitry has only one device/circuit which is used for all the steps of the method.

As explained above, the method is for tracking a work tool which is connectable to a vehicle in the form of a working machine. Such a work tool may, for instance, be a tool for carrying a load, such as a bucket, shovel, forks, gripping tool, timber grapple, material arm or excavating tool. Thus, the invention may advantageously be carried out in connection with various different working machines and work tools. According to at least one exemplary embodiment, said step of receiving a state signal indicative of the work tool being disconnected, or has been disconnected, from the vehicle, comprises:

- detecting, by using the processing circuitry, that a tool lock for locking the work tool has changed from a locked state to an unlocked state. By detecting that the tool lock no longer has the work tool in a locked state, there is a clear indication that the work tool has been disconnected or is in the process of becoming disconnected.

According to at least one exemplary embodiment, said state signal is triggered by the change from the locked state to the unlocked state. This is advantageous since there will be a direct and automatic link between the received signal and the action of unlocking the work tool. For instance, there is no need for manually confirming (e.g. on a display) that the work tool has been unlocked for triggering the state signal.

According to at least one exemplary embodiment, said step of determining the geographical position at which the work tool becomes or became disconnected comprises

- determining the geographical position of the work tool and/or the vehicle at the time of detection of said change from a locked state to an unlocked state. By determining the geographical position at the time of detection of said change, a simple synchronization between the disconnecting action and the determining of the location is obtainable. According to at least some exemplary embodiments, said step of determining the geographical position at which the work tool becomes or became disconnected comprises

- determining the geographical position of the work tool and/or the vehicle at the time of receipt of said state signal. This also provides a simple synchronization of the disconnection and the location determination. For instance, the receipt of the state signal by the processing circuitry may, in at least some exemplary embodiments, trigger the step of determining the geographical position. In other exemplary embodiments, the geographical position may be continuously monitored, for example by a means of a GPS system, and a time stamp of the receipt of the state signal is checked against a corresponding time stamp of the geographical position.

According to at least one exemplary embodiment, said step of determining the geographical position at which the work tool becomes or became disconnected comprises:

- determining the geographical position and rotational orientation of the vehicle at the time the work tool becomes or became disconnected; and

- calculating, based on the determined geographical position and rotational orientation of the vehicle, the geographical position of the work tool. This is advantageous since a GPS system of the vehicle may be used (it may even be an already existing GPS system of the vehicle, to which the processing circuitry may be operatively connected), and by knowing the position and orientation of the vehicle, the geographical position of a connected work tool may be calculated. For instance, by knowing the length, height, angle etc. of an operating arm of the vehicle to which the work tool is attached, the position of the work tool is also available, at least indirectly. There is thus no need for a tracking device on the work tool itself.

According to at least one exemplary embodiment, said step of determining the type of the work tool connected to the vehicle comprises:

- receiving an identification signal from a type-recognition component attached to the work tool, the identification signal comprising information on the type of the work tool.

Attaching a type-recognition component to the work tool is a simple way of identifying the type of work tool. For instance, the type-recognition component may be or comprise a small RFID tag. The RFID tag may be active (for instance battery-powered) or passive (for instance collecting energy from electromagnetic waves transmitted from the vehicle). Suitably, the RFID tag will only transmit a signal if subjected to an electromagnetic field, such as within a specific frequency range. The processing circuitry may suitably be used for triggering such an electromagnetic field. Such triggering may or may not be synchronized with the receiving of the state signal.

According to at least one exemplary embodiment, said identification signal, in addition to comprising information on the type of the work tool, further comprises information on the individual identity of the work tool. If there is a plurality of work tools of the same type, it may be relevant to know which individual work tool is located where. For instance, a driver may wish to use the one that is in best condition (i.e. the work tool which has been subjected to less wear).

According to at least one exemplary embodiment, the method comprises estimating the wear of the work tool based on the specific material handled by the work tool during a work operation. This is advantageous since, certain material will cause the work tool to be worn out more quickly than other materials. For instance, a work tool in the form of a bucket having bucket teeth, will be more subjected to tear when used for handling rocks compared to handling sand. By having an estimate of the wear for each individual work tool at a work site, a driver may make an informed decision when deciding which work tool to pick up for a specific working operation.

According to at least one exemplary embodiment, said one or more control units comprise a central control unit located remotely from the vehicle, wherein the step of transmitting data comprises transmitting data to said central control unit. By having a central control unit, data related to several work tools may be handled and analysed. For instance, the central control unit may comprise a central computer or the like at an office at the work site. A fleet manager may thus have a complete overview of the disconnected work tools and may instruct the drivers which tools should picked up and where. Numerous other implementations are conceivable. For instance, each individual driver may from remote access a database of the central control unit to get information on where a certain tool is located, or the drive will may just indicate which type of tool is needed and automatically get a recommendation from the central control unit on where to drive to find that type of tool.

According to at least one exemplary embodiment, said one or more control units comprise a plurality of local control units located on other vehicles, wherein the step of transmitting data comprises transmitting data to said local control units. This is advantageous since all the connected vehicles may have full access to the location of the different types of disconnected work tools at the work site. The transmission of data may either be a direct transmission from vehicle to vehicle, or via a node, such as a central control unit.

This is reflected in at least one exemplary embodiment, according to which the step of transmitting data comprises transmitting data to said local control units via said central control unit.

According to a second aspect of the invention, there is provided a computer program comprising program code means for performing the steps of the method of the first aspect, including any embodiment thereof, when said program is run on a computer.

According to a third aspect of the invention, there is provided a computer readable medium carrying a computer program comprising program code means for performing the steps of the method of the first aspect, including any embodiment thereof, when said program product is run on a computer. According to a fourth aspect of the invention, there is provided a control unit for tracking work tools on a work site, the control unit being a first control unit configured to perform the steps of the method of the first aspect, including any embodiment thereof, wherein in said step of transmitting data to one or more control units, said one or more control units is/are one or more second control units.

Each one of said control units, i.e. each one of said first control unit and said one or more second control units, may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. Each one of the control units may also, or instead, include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the control unit includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device.

The advantages of the second, third and fourth aspects of the invention are largely analogous to the advantages of the first aspect of the invention.

According to a fifth aspect of the invention, there is provided a system for tracking work tools on a work site, the system comprising the control unit according to the fourth aspect, including any embodiment thereof.

The advantages of the fifth aspect of the invention are largely analogous to the advantages of the first, second, third and fourth aspects of the invention.

Furthermore, the fifth aspect of the invention has numerous exemplary embodiments, some of which are presented below.

According to at least one exemplary embodiment of the system, the control unit is a first control unit located on a first vehicle, wherein the system comprises second, local control units, each local control unit being located on a respective vehicle different from said first vehicle, wherein the first control unit is configured to transmit data comprising information on the type of work tool and said geographical position to the local control units, for enabling guiding of the respective vehicles to the geographical position for connecting the work tool. This is advantageous, since the information is shared between the vehicles, allowing drivers in the different vehicles to find and pick up work tools that have been disconnected from the other vehicles. The second local control units are suitably operatively connected to a user interface, such as a graphical user interface, for instance, a display, allowing the driver to see which type of work tool that has been disconnected at which location.

According to at least one exemplary embodiment, the system comprises a central control unit, wherein the first control unit is configured to transmit said data to the central control unit. Thus, a fleet manager may centrally receive information on what type of work tool has been disconnected at which location, and may thus instruct drivers where to pick them up.

According to at least one exemplary embodiment, wherein the central control unit is configured to forward to the local control units said data received from the first control unit. Thus, the central control unit may function as a node via which the local control units in the vehicles can share information with each other.

According to at least one exemplary embodiment, the system comprises a type- recognition component attached to the work tool and configured to transmit an identification signal to the first control unit. As explained previously, such a type- recognition component may, for instance, be a passive RFID tag which may be triggered by an electromagnetic field, or it may actively send a signal. It should be understood that the identification signal may be sent directly to the control unit or via an intermediate device operatively connected to the control unit.

According to a sixth aspect of the invention, there is provided a vehicle comprising the control unit according to the fourth aspect, including any embodiment thereof.

The advantages of the sixth aspect of the invention are largely analogous to the advantages of the first, second, third, fourth and fifth aspects of the invention.

Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

In the drawings: Fig. 1 illustrates a vehicle, which is a working machine in the form of a wheel loader, for which the inventive method and exemplary embodiments thereof may be carried out,

Fig. 2 is a schematic illustration of a method in accordance with at least one exemplary embodiment of the invention,

Fig. 3 is a schematic illustration of a method in accordance with at least another exemplary embodiment of the invention,

Fig. 4 is a schematic illustration of a system in accordance with at least one exemplary embodiment of the invention, and

Fig. 5 is a schematic illustration of an implementation of at least one exemplary embodiment at a work site.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

Fig. 1 illustrates a vehicle, which is a working machine in the form of a wheel loader, for which the inventive method and exemplary embodiments thereof may be carried out. It should be noted however, that the wheel loader 1 is just an example and that the invention may be applied to other working machines, such as articulated haulers, excavators, forwarders and backhoe loaders. Furthermore, the invention is applicable within various technical fields, including industrial construction, agriculture, mining and forestry. The wheel loader 1 has a forward machine part/front frame 3 and a rear machine part/rear frame 5. Each of the machine parts/frames comprises two drive wheels or road wheels 7. The rear machine part 5 comprises a cab 9 for an operator of the wheel loader 1. The machine parts 3, 5 are connected to each other in such a way that they can pivot relative to each other about a vertical axis by means of one or two hydraulic cylinders (steering cylinders) 1 1a, 1 1 b which are arranged between the machine parts 3, 5 and attached thereto. The hydraulic cylinders 11 a, 1 1 b are thus arranged one on each side of a centre line extending in the longitudinal direction of the working machine 1 in order to turn or steer the wheel loader 1 by means of the hydraulic cylinders 1 1a, 11 b. In other words, the wheel loader 1 is a so called frame-steered working machine. However, it should be understood that the invention is by no means limited to working machines with this type of steering mechanism, and that other working machines with other types of steering mechanisms may also benefit from the implementation of the present invention.

The wheel loader 1 comprises a lift arm unit 15 to which a work tool 17 may be connected and disconnected, by means of a tool lock 18. In this example, the work tool 17 is illustrated in the shape of a bucket which is mounted on the lift arm unit 15. It should be understood that although the work tool 17 has been illustrated as a bucket, other types of work tools may also be connected to the lift arm unit 15, such as a shovels, forks, gripping tools, material arms or excavating tools.

In the illustrated example the bucket 17 is filled with material 19. A first end of the lift arm unit 15 is pivotally connected to the forward machine part 3 in order to achieve a lift motion of the bucket 17. The bucket 17 is pivotally connected to a second end of the lift arm unit 15 in order to achieve a tilt motion of the bucket 17. The lift arm unit 15 can be raised and lowered relative to the forward machine part 3 of the vehicle by means of two hydraulic cylinders (lift cylinders) 21 a, 21 b. Each of the hydraulic cylinders 21a, 21 b is at a first end thereof coupled to the forward machine part 3 and at the second end thereof to the lift arm unit 15. The bucket 17 can be tilted relative to the lift arm unit 15 by means of a further hydraulic cylinder (tilt cylinder) 23, which at a first end thereof is coupled to the forward machine part 3 and at the second end thereof is coupled to the bucket 17 via a link arm system.

The wheel loader 1 may also comprise a drive system (not illustrated) which may include one or more drive units, each of which including a drive motor, a gear box and at least one drive wheel 7. The drive units can be driven independently of each other, i.e. the torque applied by one drive unit can be varied independently of the torque applied by another drive unit.

Inside the wheel loader 1 , there may be a processing circuitry, for implementing a tracking of the bucket 17 when it is being disconnected or has been disconnected from the lift arm unit 15 (for instance, including the detection of the tool lock 18 being changed from a locked state to an unlocked state). The processing circuitry may share the tracking information with other or corresponding processing circuitries in other vehicles and/or with in other locations such as a fleet manager’s office. The processing circuitry may comprise, or may be comprised in, a control unit for performing the steps of the inventive method, including any embodiments of the inventive method.

Fig. 2 is a schematic illustration of a method 100 in accordance with at least one exemplary embodiment of the invention. The method 100 is for tracking work tools on a work site, the method comprising:

- in a first step S1 , determining, by a processing circuitry, that a work tool is connected to a vehicle in the form of a working machine;

- in a second step S2, identifying, using the processing circuitry, the type of the work tool being connected to the vehicle;

- in a step S3, receiving, at the processing circuitry, a state signal indicative of the work tool being disconnected, or has been disconnected, from the vehicle;

- in a step S4, determining, using the processing circuitry, the geographical position at which the work tool becomes or became disconnected from the vehicle; and

- in a step S5, transmitting, from the processing circuitry, data comprising information on the type of work tool and said geographical position to one or more control units, wherein the transmitted data enables subsequent guiding of the vehicle or another vehicle to the geographical position for connecting the work tool.

It should be understood that the above steps do not necessarily have to be performed in the listed order. For instance, steps S2 and S3, may be performed simultaneously, or step S3 may even be performed prior to step S2. Thus, it may not be necessary to identify the type of work tool beforehand. It may be enough to perform said identifying step (S2) while the work tool is being disconnected or even after it has become disconnected. Similarly, steps S3 and S4 may be performed simultaneously. Whatever action triggers a state signal may also be used for triggering a location determining signal.

The first step S1 , determining, by a processing circuitry, that a work tool is connected to a vehicle, may for instance be triggered by a tool lock. For instance, when a work tool is attached to the vehicle a tool lock may be used which can change between an unlocked state and a locked state. When such a change is done, i.e. when the work tool becomes locked to the vehicle, a state signal may be triggered and received by the processing circuitry for determining that a work tool has been connected to the vehicle. Such a tool lock may suitably be provided on e.g. an end portion of a lift arm unit of a vehicle in the form of a working machine. In other exemplary embodiments, it is conceivable, that a driver enter via a user interface a confirmation command, that the work tool has been connected, which user interface is operatively connected to the processing circuitry. In at least some exemplary embodiments, after the determination that a work tool is connected, the following step may be performed: transmitting, by using the processing circuitry, data to the one or more control units that the work tool has been connected. Suitably, this may cancel any previous received data at said one or more control units relating to the work tool having been disconnected. The cancellation may, for example, be based on a type or an individual identity of the working machine (for instance, based on the identification in step S2 or another identification step) or based on the location where the work tool was picked up (for instance, by using a positioning system, such as a GPS system). The control unit or control units receiving the data may make the cancellation based on a comparison with previously received data relating to the same geographical position or the same type/identity of the work tool.

The second step S2, identifying, using the processing circuitry, the type of work tool being connected to the vehicle, may be carried out in various ways. For instance, a type- recognition component may be attached to the work tool and be configured to transmit an identification signal to the processing circuitry. The identification signal may thus comprise information on the type of the work tool and may be received by the processing circuitry. As already explained, the type-recognition component may be or may comprise a small RFID tag or other means for communicating the information. For instance, the type recognition component may comprise a radio transmitter, Bluetooth transmitter, etc. In other exemplary embodiments, it is conceivable to have a user interface into which a driver may manually enter the type of work tool connected to the vehicle. In further exemplary embodiments, the step S2 of identifying, may include reading or scanning a code, such as a bar code, QR code, etc., attached to the work tool. A scanner or reader may be provided on the vehicle (or be handled manually by a driver), wherein the scanner or reader may send an identification signal to the processing circuitry, whereby the type of work tool connected to the vehicle is identified.

The above-mentioned identification signal may, in addition to comprising information on the type of the work tool, further comprises information on the individual identity of the work tool. Thus, the identification signal does not necessarily only provide information on the type of work tool (for example, forks, grapple, large bucket, small bucket, etc.), but may also provide information on the individual identity (for example fork #4, large bucket #2, etc.). If the individual work tools are associated with further parameters, such as number of hours they have been used, the material for which they have been used, etc. it may provide an indication on the amount of wear of the individual work tool. A driver may for example select large bucket #2 rather than large bucket #3 because he/she knows or retrieves information indicating that large bucket #2 is in better condition than large bucket #3.

The third step S3, receiving, at the processing circuitry, a state signal indicative of the work tool being disconnected, or has been disconnected, from the vehicle, may in at least some exemplary embodiments be based on the state of a tool lock. Thus, in at least some exemplary embodiments, in which the vehicle is equipped with a suitable tool lock for locking the work tool, the third step S3 may comprise detecting, by using the processing circuitry, that a tool lock for locking the work tool has changed from a locked state to an unlocked state. For instance, the state signal may be triggered by the change from the locked state to the unlocked state. Another state signal may be triggered when changing back from the unlocked state to the locked state (for example for step S1 ).

The fourth step S4, determining, using the processing circuitry, the geographical position at which the work tool becomes or became disconnected from the vehicle, may be carried out in various ways. In some exemplary embodiments, the geographical position of the work tool and/or the vehicle is determined at the time of receiving the state signal (step S3), for instance at the time of detection of a tool lock changing from a locked state to an unlocked state. The geographical position of the work tool may be indirectly determined. For instance, by determining the geographical position and rotational orientation of the vehicle as such, and knowing the relationship between the vehicle and the work tool (e.g. the length and position of a lift arm unit of the vehicle), it is possible to calculate the geographical position of the work tool. The geographical position of the vehicle may be determined by any suitable positioning system, using for example triangulation. Suitably, the vehicle may be equipped with a positioning system, such as for instance a GPS system. For certain work sites or under certain conditions, GPS systems are not adequate. For instance, in underground mining, GPS signals may not be correctly communicated. Other means for determining the position of the implement or the working machine may instead be used. Other types of positioning systems, such as RFID based, laser scanning based, and other types of positioning systems are conceivable alternatives to GPS systems.

The fifth step S5, transmitting, from the processing circuitry data comprising information on the type of work tool and said geographical position to one or more control units, may also be carried out in various ways. As will be discussed with reference to other drawing figures, the control units may be provided in other vehicles and/or may be provided centrally in for example a fleet manager’s office. The transmission of data may thus include transmission to a central control unit and/or to local control units on other vehicles. The transmission of data may go directly to the local control units or via a node, such as a central control unit.

Fig. 3 is a schematic illustration of a method in accordance with at least another exemplary embodiment of the invention. In addition to the method discussed in connection with Fig. 2, the method of Fig. 3 comprising a sixth step S6, estimating the wear of the work tool based on the specific material handled by the work tool during a work operation. For instance, heavy stones and other hard material is known to affect the condition of a work tool more than sand and other less hard material. By for example logging the type of material handled, the time length and frequency of the handling, an estimation may be made of the condition of the work tool. The estimation may, for instance, be based on previous empirical studies and/or other calculations.

Although Fig. 3 illustrates that the step S6 is performed after step S5, it should be understood that a different order is conceivable. Indeed, the sixth step S6 may be performed before, simultaneously with, or after any one of the steps S1-S5. By having the estimation of the wear of the work tool from step S6, and by having the information of the geographical location of different disconnected work tools at the work site, a driver or a fleet manager, may make an informed decision on which work tool to use for which operation, and direct a vehicle to pick-up the work tool accordingly. A work tool in better condition may be preferred for a certain working operation and/or material handling, while another work tool in worse condition may be good enough for some other working operation and/or material handling.

Fig. 4 is a very schematic illustration of a system 30 in accordance with at least one exemplary embodiment of the invention. The largest rectangle in Fig. 4 represents a vehicle 40 in the form of a working machine. A work tool 50 is connected to the vehicle by means of a tool lock 60.

The vehicle 40 comprises a control unit 62 for tracking work tools on a work site. The control unit 62 may comprise or may be comprised in a processing circuitry. The processing circuitry may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. The processing circuitry may also, or instead, include an application specific integrated circuit, a programmable gate array or programmable array logic, a programmable logic device, or a digital signal processor. Where the processing circuitry includes a programmable device such as the microprocessor, microcontroller or programmable digital signal processor mentioned above, the processor may further include computer executable code that controls operation of the programmable device. It should be understood that all or some parts of the functionality provided by means of the processing circuitry (or generally discussed as “processing circuitry”) may be at least partly integrated with the control unit 62.

For simplicity, in the following reference will only be made to the control unit 62. However, it should be understood that the interactions with the different components discussed below may be performed by a processing circuitry which forms part of the control unit 62 or which includes the control unit 62.

The vehicle 40 is further provided with a positioning system 64, such as a GPS system for detecting the positioning of the vehicle 40 which may indirectly be recalculated, e.g. by the control unit 62, to a geographical position of the work tool 50. The work tool is provided with a type-recognition component 66 attached to the work tool 50 and configured to transmit an identification signal to the first control unit 62. The type- recognition component 66 may, for instance, comprise an RFID tag, which may be activated by an electromagnetic field generated by an EM field device 68 provided on the vehicle. The EM field device 68, or another device may be arranged to receive the identification signal and to forward the information represented by the signal to the control unit 62 (this forwarding of the information is represented by arrow 70). Thus, in the illustrated exemplary embodiment, the identification signal is sent from the type- recognition component 66 to the control unit 62 via an intermediate device, i.e. via the EM field device 68. It should be understood that that the identification signal may be transformed into another format by the EM field device 68, but should within the scope of the present disclosure still be interpreted as that identification signal being sent from the type-recognition component 66 to the control unit 62, at least indirectly. In other exemplary embodiments, the identification signal may be received directly by the control unit 62.

In use, when a driver wants to disconnect the work tool 50 from the vehicle 40, the tool lock 60 will be changed from a locked state to an unlocked state, whereby the work tool 50 can be released from the vehicle 40. The unlocking of the work tool 50 triggers a state signal which is detected by the control unit 62 (the state signal is represented by arrow 72). The control unit 62 determines by means of the positioning system 64 at which geographical position the work tool 50 is becoming or has been disconnected (the information received from the positioning system is represented by arrow 74). Prior to, simultaneously with, or after the disconnection, the EM field device 68 activates the type- recognition component 66 which transmits an identification signal which is detected by the EM field device 68 which forwards the identification signals (arrow 70), or another signal carrying the corresponding type-identifying information, to the control unit 62. The control unit 62 transmits data comprising information on the type of work tool 50 and said geographical position of the disconnected work tool 50 to at least one externally located control unit 78 (the transmission, which may suitably be wireless, is represented by arrow 76). The transmitted data enables subsequent guiding of the vehicle 40 or another vehicle to the geographical position for connecting/reconnecting the work tool 50. The externally located control unit 78 may be a local control unit in another vehicle or a central control unit of, for instance, a fleet manager. Fig. 5 is a schematic illustration of an implementation of at least one exemplary embodiment at a work site.

Fig. 5 illustrates three vehicles 80a, 80b, 80c in the form of working machines, such as wheel loaders. However, it should be understood that the invention may be implemented also for a mix of different vehicles and different work tools. At the work site, there is a fleet manager base 82. The fleet manager base 82 is here schematically illustrated as a building, however, it could just as well be another vehicle.

Each one of the three vehicles 80a, 80b and 80c is provided with a control unit 84a, 84b and 84c, respectively, which comprises or which is comprised in a processing circuitry, for performing the inventive method of tracking work tools. The fleet manager base 82 may be provided with a central control unit 86, which may also comprise or which may also be comprised in a processing circuitry.

Fig. 5 illustrates a situation in which a first vehicle 80a has just disconnected a work tool 88a. The control unit 84a of the first vehicle 80a has determined that the work tool 88a has been disconnected, has identified the type of work tool and has determined the geographical position where the work tool 88a was disconnected. The control unit 84a of the first vehicle 80a may transmit data with this information to the control units 84b, 84c of the other vehicles 80b, 80c and/or to the central control unit 86 of the fleet manager base 82. As explained previously, in at least some exemplary embodiments, the central control unit 86 may function as a node which is configured to forward to the local control units 84b, 84c the data received from the control unit 84a of the first vehicle 80a. The second vehicle 80b is currently driven with a work tool 88b attached, and it is for the present discussion therefore assumed that the driver does not want to pick up the disconnected work tool 88a (although it is conceivable that in some cases the driver would like to switch work tools, in which case the information would be relevant to the driver of the second vehicle 80b). The third vehicle 80c, however, does not have a work tool connected. For the present discussion it is assumed that the driver of the third vehicle 80c wants to start a working operation involving using the type of work tool 88a that has been disconnected from the first vehicle 80a. The data received by the control unit 84c of the third vehicle 80c from the control unit 84a of the first vehicle 80a will guide the driver of the third vehicle 80c to the geographical position for connecting the work tool 88a. The control unit 84c may suitably be operatively connected to or may comprise a user interface, such as a graphical user interface, from which the driver may access the relevant information. Similarly, the other control units 84a, 84b and 86 may suitably be operatively connected to or comprise a respective similar user interface. It should be understood that if the third vehicle 80c does not pick up the work tool 88a, any other vehicle, including the first vehicle 80a which previously disconnected the work tool 88a will have information of where to pick-up that specific work tool 88a.

In at least some exemplary embodiments, when a work tool has been picked up and connected to a vehicle, the control unit of that vehicle may transmit data in that regard for cancelling or updating the previously transmitted data of where the work tool had been disconnected, thereby avoiding that a driver comes looking for a work tool which has already been picked up. It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

1. A computer implemented method (100, 200) for tracking work tools on a work site, the method comprising the steps of:

- determining (S1 ), by a processing circuitry, that a work tool is connected to a vehicle in the form of a working machine;

- identifying (S2), using the processing circuitry, the type of the work tool being connected to the vehicle;

- receiving (S3), at the processing circuitry, a state signal indicative of the work tool being disconnected, or has been disconnected, from the vehicle;

- determining (S4), using the processing circuitry, the geographical position at which the work tool becomes or became disconnected from the vehicle; and

- transmitting (S5), from the processing circuitry, data comprising information on the type of work tool and said geographical position to one or more control units, wherein the transmitted data enables subsequent guiding of the vehicle or another vehicle to the geographical position for connecting the work tool.

2. The method (100, 200) according to claim 1 , wherein said step of receiving (S3) a state signal indicative of the work tool being disconnected, or has been disconnected, from the vehicle, comprises:

- detecting, by using the processing circuitry, that a tool lock for locking the work tool has changed from a locked state to an unlocked state.

3. The method (100, 200) according to claim 2, wherein said state signal is triggered by the change from the locked state to the unlocked state.

4. The method (100, 200) according to claim 2 or 3, wherein said step of determining (S4) the geographical position at which the work tool becomes or became disconnected comprises

- determining the geographical position of the work tool and/or the vehicle at the time of detection of said change from a locked state to an unlocked state.

5. The method (100, 200) according to any one of claims 1-4, wherein said step of determining (S4) the geographical position at which the work tool becomes or became disconnected comprises: - determining the geographical position and rotational orientation of the vehicle at the time the work tool becomes or became disconnected; and

- calculating, based on the determined geographical position and rotational orientation of the vehicle, the geographical position of the work tool.

6. The method (100, 200) according to any one of claims 1-5, wherein said step of identifying (S2) the type of the work tool connected to the vehicle comprises:

7. The method (100, 200) according to claim 6, wherein said identification signal, in addition to comprising information on the type of the work tool, further comprises information on the individual identity of the work tool.

8. The method (200) according to any one of claims 1-7, comprising estimating (S6) the wear of the work tool based on the specific material handled by the work tool during a work operation.

9. The method (100, 200) according to any one of claims 1-8, wherein said one or more control units comprise a central control unit located remotely from the vehicle, wherein the step of transmitting (S5) data comprises transmitting data to said central control unit.

10. The method (100, 200) according to any one of claims 1-9, wherein said one or more control units comprise a plurality of local control units located on other vehicles, wherein the step of transmitting (S5) data comprises transmitting data to said local control units.

1 1. The method (100, 200) according to claim 10 when dependent on claim 9, wherein the step of transmitting data comprises transmitting data to said local control units via said central control unit.

12. A computer program comprising program code means for performing the steps of any of claims 1-11 when said program is run on a computer.

13. A computer readable medium carrying a computer program comprising program code means for performing the steps of any of claims 1-1 1 when said program product is run on a computer.

14. A control unit (62, 84a) for tracking work tools (50, 88a) on a work site, the control unit (62, 84a) being a first control unit configured to perform the steps of the method (100, 200) according to any of claims 1-1 1 , wherein in said step of transmitting (S5) data to one or more control units (78, 84b, 84c, 86), said one or more control units (78, 84b, 84c, 86) is/are one or more second control units.

15. A system (30) for tracking work tools (50, 88a, 88b) on a work site, comprising a control unit according to claim 14.

16. The system (30) according to claim 15, wherein the control unit (62, 84a) is a first control unit located on a first vehicle (40, 80a), wherein the system comprises second, local control units (78, 84b, 84c), each local control unit being located on a respective vehicle (80b, 80c) different from said first vehicle (40, 80a), wherein the first control unit (62, 84a) is configured to transmit data comprising information on the type of work tool (88a) and said geographical position to the local control units (78, 84b, 84c), for enabling guiding of the respective vehicles (80b, 80c) to the geographical position for connecting the work tool (88a).

17. The system (30) according to claim 15 or 16, comprising a central control unit (78, 86), wherein the first control unit (62, 84a) is configured to transmit said data to the central control unit (78, 86).

18. The system (30) according to 17, wherein the central control unit (86) is configured to forward to the local control units (84b, 84c) said data received from the first control unit (84a).

19. The system (30) according to any one of claims 15-18, comprising a type-recognition component (66) attached to the work tool (50) and configured to transmit an identification signal to the first control unit (62).

20. A vehicle (1 , 40, 80a, 80b, 80c) comprising a control unit (62, 84a, 84b, 84c) according to claim 14.