SE545170C2 - Improved manner of detecting wire break for a robotic working tool system - Google Patents

Abstract

A method for use in a robotic working tool system (100) comprising a boundary wire (120), one or more guide wires (120G), and a signal generator (114), wherein the one or more guide wires (120G) are connected at each one end to the boundary wire (120) and at the other ends to the signal generator (114), and wherein the method comprises: transmitting a test signal (125) through the boundary wire (120); determining which of the one or more guide wires (120G) are active; and determining which portion (B0, Bl, B2, BN) of the boundary wire (120) in which there is a break.

Description

IMPROVED MANNER OF DETECTING WIRE BREAK FOR A ROB OTIC WORKING TOOL SYSTEM TECHNICAL FIELD This application relates to robotic Working tools and in particular to a system and a method for providing an improved manner of detecting Wire break for a robotic Working tool system, such as a laWnmoWer system.

BACKGROUND Automated or robotic Working tools, such as robotic laWnmoWers, are becoming increasingly more popular. In a typical deployment a Work area, such as a garden, the Work area is typically bounded by a boundary Wire through Which an electrical control signal is transmitted generating a magnetic field that is detectable by the robotic Working tool. In this manner a perimeter is established inside Which the robotic Working tool is set to Work.

Such a boundary Wire is typically buried in the ground and is thus not easy to see.

As a garden is subjected to many kinds of extemal factors, such as garden Work, children playing, animals digging and so on, the boundary cable may be subjected to be broken by such external factors. The break may be a cut in the boundary Wire or a separation of a connector splicing tWo portions of the boundary Wire.

As the Wire is underground, so is the break and is thus difficult to find, often requiring the Wire to be dug out, Which is a big task for most garden oWners.

Several tools and methods are available for finding such a break, for example a portable device that checks the integrity of the Wire, Which a user carries around the perimeter in order to spot Where the break has occurred.

Such knoWn methods, hoWever, still require the user to traverse the length of the perimeter, Which in some cases can be a fairly large area.

Thus, there is a need for an improved manner of finding a break that does not require a traversal of potentially the Whole perimeter.

SUMMARY It is therefore an object of the teachings of this application to overcome or at least reduce those problems by providing a robotic Working tool system comprising a boundary Wire, one or more guide Wires, and a signal generator comprising a controller, Wherein the one or more guide Wires are connected at each one end to the boundary Wire and at the other ends to the signal generator, and Wherein the controller is configured to: transrnit a test signal; determine Which Wires are active; and determine Which portion of the boundary Wire in Which there is a break.

In one embodiment the controller is further configured to transmit the test signal through the boundary Wire.

In one embodiment the controller is further configured to transmit the test signal through a guide Wire.

In one embodiment the controller is further configured to: transmit a second test signal through at least one of the one or more guide Wires; determine Which of the boundary Wire and/or Which of the remaining one or more guide Wires are active; and determine Which portion of the boundary Wire and/or Which of the one or more guide Wires in Which there is a break.

In one embodiment the controller is further configured to: detect that there is a break in the boundary Wire prior to transmitting the test signal through the boundary Wire.

In one embodiment the controller is further configured to: transmit the test signal through a guide Wire subsequent to the boundary portion detected to have a break; determine Which of the remaining and subsequent of the one or more guide Wires that are active; and determine Which portion of the boundary Wire in Which there is a second break.

In one embodiment the controller is further configured to determine that there are no more breaks in the boundary Wire if all of the remaining and subsequent of the one or more guide Wires are active.

In one embodiment the signal generator further comprises a user interface, Wherein the controller is configured to display an indication of the portion of the boundary Wire in Which there is a break in a display portion of the user interface.

In one embodiment the robotic Working tool system further comprises an external device comprising a user interface, Wherein the display portion of the user interface of the signal generator is a display portion of the user interface of the external device.

In one embodiment the robotic Working tool system further comprises a robotic Working tool configured to deterrnine its position, Wherein the display portion of the user interface of the external device is configured to display a representation of a map of the Work area, and to display the indication of indication of the portion of the boundary Wire in Which there is a break in the representation of the map of the Work area.

In one embodiment the controller is further configured to transmit the test signal even if no break is detected, and determine Whether there is any inconsistency in Which guide Wires are active, and if so deterrnine that at least one of the one or more guide Wires is incorrectly connected.

In one embodiment the signal generator is further configured to generate and transmit a control signal through the boundary Wire and Wherein the test signal is the control signal.

In one embodiment the signal generator is further configured to generate and transmit a control signal through the boundary Wire and Wherein the test signal is not the control signal.

In one embodiment the robotic Working tool is a robotic laWnmoWer.

It is also an object of the teachings of this application to overcome the problems by providing a method for use in a robotic Working tool system comprising a boundary Wire, one or more guide Wires, and a signal generator, Wherein the one or more guide Wires are connected at each one end to the boundary Wire and at the other ends to the signal generator, and Wherein the method comprises: transmitting a test signal; deterrnining Which of the one or more guide Wires are active; and determining Which portion of the boundary Wire in Which there is a break.

Other features and advantages of the disclosed embodiments will appear from the following detailed disclosure, from the attached dependent claims as well as from the drawings. Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a/an/the [element, device, component, means, step, etc.]" are to be interpreted openly as referring to at least one instance of the element, device, component, means, step, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in further detail under reference to the accompanying drawings in which: Figure l shows an example of a robotic working tool system according to an example embodiment of the teachings herein; Figure 2 shows a schematic view of a robotic working tool system according to an example embodiment of the teachings herein; Figure 3 shows a schematic view of a robotic working tool system according to an example embodiment of the teachings herein; and Figure 4 shows a corresponding flowchart for a method according to an example embodiment of the teachings herein.

DETAILED DESCRIPTION The disclosed embodiments will now be described more fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like reference numbers refer to like elements throughout.

It should be noted that even though the description given herein will be focused on robotic lawnmowers, the teachings herein may also be applied to, robotic ball collectors, robotic mine sWeepers, robotic farming equipment, or other robotic Working tools set to operate in a Work area bounded by a boundary Wire.

Figure 1 shows a schematic vieW of a robotic Working tool system 100 in one embodiment. The schematic vieW is not to scale. The Work area 105 is in this application eXemplified as a garden, but can also be other Work areas as Would be understood. The Work area may also comprise more than one sub Work areas possibly connected by one or more transport paths. The garden contains a number of objects or structures. In the example of figure 1, there are different types of objects: a tree T, a boulder B, slopes (exemplified by a slope S) and slipping areas (exemplified by a muddy area M).

The robotic Working tool system 100 comprises a charging station 110, Which in some embodiments is arranged With a signal generator 114, and a boundary Wire 120. In some embodiments, the signal generator 114 is a standalone device. The boundary Wire 120 is arranged to enclose a Work area 105, in Which the robotic laWnmoWer 130 is supposed to serve. The signal generator 114 is arranged to generate a control signal 125 to be transmitted through the boundary Wire 120. When the control signal 125 is transmitted through the boundary Wire 120, the signal 125 causes a magnetic field (not shown) to be emitted.

The robotic Working tool system 100 comprises a robotic Working tool 130. In some embodiments the robotic Working tool 130 is eXemplified by a robotic laWnmoWer, Whereby the robotic Working tool system may be a robotic laWnmoWer system or a system comprising combinations of robotic Working tools, one being a robotic laWnmoWer. HoWever, the teachings herein may also be applied to other robotic Working tools adapted to operate Within a Work area 105 bounded by a boundary Wire.

For enabling the robotic laWnmoWer 130 to navigate With reference to the boundary Wire 120 emitting the magnetic field caused by the control signal 125 transrnitted through the boundary Wire, the robotic laWnmoWer 130 is further configured to have at least one magnetic field sensor arranged to detect the magnetic field (not shoWn) and for detecting the boundary Wire. This enables the robotic laWnmoWer 130 to determine Whether the robotic laWnmoWer 130 is close to or crossing the boundary wire, or inside or outside an area enclosed by the boundary wire and enables for maintaining the robotic lawnmower 130 inside the work area The signal generator 114 is also configured to be connected to one or more guide wires 120G, and to generate and transmit each a guide control signal 125G through the one or more guide wires 120G. This enables the robotic lawnmower 130 to be guided out to a portion of the work area 105 more easily, and/or to be guided back to the charging station more easily. Guide wires are commonly known and will not be discussed in further detail except that it should be noted that a guide wire 120G as discussed herein is connected at one end to the signal generator 114 and at the other end to the boundary wire 120. It should also be noted that other guide wires (such as F-field wires, N-field wires or looped guide wires) may be connected to the signal generator 1 In one embodiment the control signal 125 is a sinusoid periodic current signal. In one embodiment the control signal 125 is a pulsed current signal comprising a periodic train of pulses. ln one embodiment the control signal 125 is a coded signal, such as a CDMA signal. This also applies to the guide control signal 125, and no difference will be made between different types of control signals 125(G) unless specifically indicated.

The signal generator 114 is operably connected to (as in being connected to or comprising) a controller 111 for controlling the overall operation of the signal generator 114 and a computer readable storage medium or a memory 112 for storing computer-readable instructions and data that when loaded into and eXecuted by the controller 111 provides instructions for how the signal generator 114 is controlled. The controller 111 may be implemented using instructions that enable hardware functionality, for example, by using eXecutable computer program instructions in a general-purpose or special-purpose processor that may be stored on the memory 112 to be eXecuted by such a processor. The controller 110 may be implemented using any suitable, available processor or Programmable Logic Circuit (PLC). The memory 120 may be implemented using any commonly known technology for computer-readable memories such as ROM, RAM, SRAM, DRAM, FLASH, DDR, SDRAM or some other memory technology.

The signal generator 114 is, in some embodiments, operably connected to (as in being connected to or comprising) a Wireless communication interface 113 for communicating with other devices, such as a server, a personal computer or smartphone, and/or robotic Working tools. EXamples of such wireless communication devices are Bluetooth®, WiFi® (IEEE802. 1 lb), Global System Mobile (GSM) and LTE (Long Term Evolution), to name a few. In some embodiments, the wireless interface comprises the signal generator 114 whereby the signal generator generates and transmits information signals that are transmitted through the boundary wire 120 and received by the robotic lawnmower In embodiments where the signal generator 114 comprises a communication interface 113, the memory 112 may be seen as comprising external storage, wherein data may be retrieved from such eXtemal storage. For the purpose of this application no difference will be made between a local memory 112 and an eXtemal memory accessed through a communication interface The signal generator 114 is, in some embodiments, operably connected to (as in being connected to or comprising) a user interface 115. The user interface comprises a display portion enabled to visually display or visually indicate a portion of the boundary wire.

In some embodiments, the display portion comprises a display such as a Liquid Crystal Display (LCD) enabled to graphically indicate a portion of the boundary wire.

In some embodiments, the display portion comprises a text output enabled to teXtually indicate a portion of the boundary wire. In such an embodiment, the display portion is beneficially paired with a graphic indicating a correspondence between the textual output and the boundary wire.

In some embodiments, the display portion comprises a light emitting diode (LED) array enabled to indicate a portion of the boundary wire. ln such en embodiment, each LED may be associated with a boundary portion and activation/deactivation of the LEDs can indicate the boundary portion.

In some embodiments, the user interface 115 (and specifically the display portion) is arranged on the charging station In some embodiments, the user interface 115 (and specifically the display portion) is arranged on the robotic lawnmower 130. In such embodiments, the signal generator 114 is arranged to communicate the information to be displayed to the robotic lawnmower 130 through the communication interface In some embodiments, the user interface 115 (and specifically the display portion) is arranged on an extemal device (not shown in figure 1, but referenced 200 in figure 2). In such embodiments, the signal generator 114 is arranged to communicate the information to be displayed to the external device (200) through the communication interface Figure 2 shows a simplified schematic view of the robotic Working tool system 100 according to figure 1. In figure 2, the robotic Working tool system 100 comprises two guide wires 120G1 and 120G2, herein also referred to as G1 and G The robotic working tool system 100 also comprises or is at least arranged to be connected to an external device 200. The extemal device may be a server 200. The server 200 may be a standalone device or executed by a smart phone, a personal computer or other commonly known household computing device. The external device may be a server 200. The server 200 may be a standalone device or executed by a smart phone, a personal computer or other commonly known household computing device. The server 200 may also or alternatively be executed as a cloud service.

The extemal device 200 comprises a controller 211 configured to control the overall operation of the extemal device 200 and a memory configured to store instructions and data that are read by, loaded into and executed by the controller 211. The controller 211 and the memory 212 may be of a similar type as the controller 111 and memory 112 of the signal generator 114, as discussed above.

The extemal device 200 also comprises a communication interface 213 configured to connect the external device with the signal generator 114, either directly or indirectly through another device, such as the robotic lawnmower 130. The communication interface 213 may be of a similar type as the communication interface 113 of the signal generator 114, as discussed above.

The extemal device 200 also comprises a user interface 215 comprising a display portion configured to display or otherwise visually indicate a portion of the boundary Wire 120. The user interface 215 may be of a similar type as the user interface 115 of the signal generator 114, as discussed above. In some embodiments the display portion of the user interface 215 operates as the display portion of the user interface 1 In the example of figure 2, the display portion of the user interface 215 of the external device displays a stylized version of the robotic Working tool system 100, Wherein three portions of the boundary Wire are possible to indicate; B0, Bl and B2. The numbering is of course only for illustrating purposes and the actual labelling may be of any type, including graphical highlighting.

In order to determine or detect Where a break has occurred in the boundary Wire (or in a guide Wire) the controller 111 is configured to transmit a test signal 125 through the boundary Wire 120 by causing the signal generator 114 to do so. The controller 111 is further configured to measure the resistance in the one or more guide Wires 120G and based thereon determine in Which portion of the boundary Wire 120, the break has occurred.

With reference to the example of figure 2, Where two guide Wires are used, and Where the user interface 215 of the extemal device 200 is utilized to indicate the boundary portion, the test signal 125 is, in some embodiments, transmitted through the boundary Wire 120 for enabling resistance measuring in the guide Wires 120G, in the example of figure 2 at points P1 and P2. In some embodiments, the resistance measuring is performed by simply detecting if the test signal 125 is received through the various guide Wires 120G.

In some embodiments, the test signal 125 is transmitted through the one or more of the guide Wires 120G for enabling resistance measuring in the other guide Wires 120G or in the boundary Wire 120. In some embodiments, the resistance measuring is performed by simply detecting if the test signal 125 is received at the boundary Wire after being transmitted through the various guide Wires 120G.

As a skilled person Would realize, transmitting through any of the guide Wires or through the boundary Wire Will have the same effect.

In some embodiments the test signal 125 is transmitted as a break has been detected in the boundary Wire In the example of figure 2, if the test signal is received at point P1, the resistance measuring indicates that the portion B0 of the boundary wire 120 before the connection with the first guide wire 120G1 is intact. And, if not, the break is in the portion B Simi1ar1y, if the test signal is received at point P2, the resistance measuring indicates that the portion B1 of the boundary wire 120 before the connection with the second guide wire 120G2 is intact. And, if not, the break is in the portion B In this manner it is possib1e to deduce that the break is in any portion not indicated to be intact. Assuming that the test signa1 is received at both P1 and P2, the break must be in the fina1 portion of the boundary; B The formu1a be1ow shows in which boundary portion the break is, based on through which guide wire the test signa1 is received, i.e. which guides are active.

ACTIVE GUIDE BoUNDARY PoRnoN W BREAK Bo G1 Bi G1, G2 Bz G1,G2,_..,GN BN The tab1e a1so shows how the scheme may be eXtrapo1ated to more than two guide wires, GN. The contro11er is thus enab1ed to identify which portion of the boundary wire that the break is in based on resistance measuring in the guide wire(s) 120G.

Transmitting through a boundary wire or through a guide wire and detecting which guide wires and/or boundary wire(s) are active can a1so be uti1ized by the robotic working too1 system to determine a break in a guide wire, as is shown in the tab1e be1ow. The robotic working too1 system is thus configured to a1so determine a break in a guide wire.

ACTIVE WIRE PORTION W BREAK NONE B0 OR G1 AND (G2 AND B2 (AND/) OR B1) ll G2 G1 AND B2 G1, B3 G2 B3 G1 AND GIt should be noted that a guide wire is considered to be active with regards to the test signal.

In some embodiments, the controller 111 of the signal generator 114 (or of the charging station in general) is configured to determine if a wire (guide or otherwise) is active if the test signal is detectable in the wire, regardless whether it is transmitted through the boundary wire or through one of the guide wires.

The user interface 215 of the external device 200 indicates which portion is broken and which are intact. This may be done by actively showing intact portions, such as highlighting the intact boundary portions. This may also be done by actively showing broken boundary portions, such as highlighting the broken boundary portions. In the example of figure 2, the break is indicated to be in the boundary portion Bl between the two guides G1, G2, and this portion is highlighted in the user interface The teachings herein may not give an exact position of the break, but at least it gives the user an indication of where to start to look, and in the example of figure 2, the work needed is reduced to a third, which is a substantial improvement.

The inventors have further realized that a more specific localization of a break may be achieved as will be discussed in the below. The inventors have also realized that more than one break may occur whereby it would be beneficial to detect the general location of all breaks. And, as the inventors have realized, both of these situations may be accomplished by transmitting the test signal 125 through at least one of the guide wires in addition to or as an alternative to transmitting the test signal through the boundary wire. This enables for a more detailed finding of the break, and also for differentiating if the break is in the boundary or in any of the guide wires.

By transmitting the test signal through a guide wire G1, and measuring the resistance in the other guide wire(s) G2, it is possible to determine a more precise location of a break as well as general locations of more than one break. In the tablebelow, the deterrr1inations of which boundary portion has the break based on which wires are active is illustrated. This also enables for detecting a break in a guide wire.

In some embodiments, and as assumed in the table below, the signal generator 114 is arranged to transmit the test signal through a guide wire in order to differentiate between a break in the boundary portion and a break in the guide wire. The test signal is transmitted through the guide wire that is detected to not be active, and the remaining wires may be monitored to see which ones become active and thereby deduce where the break is. If a test signal is transmitted through more than one guide wire, an ambiguous indication may be resolved.

EEEDING WIRE ACTIVE WIRE PORTION WITH BREAK G1 BO B1 (AND/) OR G2 AND B2 G2 BO AND B2 B2 BO AND G2 BO+G2 B2 G2+B2 BO BO+G2+B2 NO BREAK NONE G1 OR ALL G2 BO G1 AND B2 G1 BO AND B2 B2 B1 (AND/) OR G1 AND BO BO+G1 B2 G1+B2 BO BO+G1+B2 NO BREAK NONE G2 OR ALL As a skilled person would understand, similar tables may be generated for any configuration, and the example herein is only for illustrative purposes and thus only for the example given in figure In some embodiments, and as assumed in the table below, the signal generator 114 is arranged to transmit a second test signal, which in some embodimentsis the same test signal through the guide after the first detected boundary portion having a break. That is, if the first boundary portion is determined to have a break, the test signal is transmitted through the first guide Wire 120G1, and if the second boundary portion B1 is deterrnined to have a break, the test signal is transmitted through the second guide Wire 120G2, and so on. In case of such repeated finding of breaks, the resistance is also measured in the boundary Wire, at point P3, to see if the remainder of the boundary Wire is active. This also enables for securing that there are no more breaks in the boundary Wire. Naturally, the process can be repeated for each break that is found. FIRST DETECTED EEEDING ACTIVE SECOND DETECTED BOUNDARY PORTION WIRE WIRE BOUNDARY PORTION BO Gl --- B 1 Gl G2 B2 Gl G2, GN-1 BN Gl G2. . .B(P3) NO MORE BREAKS B 1 G2 --- B2 G2 ..., GN-1 BN G2 ...B(P3) NO MORE BREAKS In some embodiments, the signal generator 114 is configured to store a table such as any of the ones discussed above, in the memory 112 and to query that table When deterrnining Which portion(s) of the boundary Wire has experienced a break.

In some embodiments, the test signal 125 may be a specific test signal that is transmitted at start-up or as a break has been detected in the boundary Wire 120. This enables for specific searching for a break. In some such embodiments, the test signal is the control signal 125, and is a specific test signal in the timing of the transmission. In some such embodiments, the test signal (being the control signal is the normal controlsignal, timed as expected. In alternative or additional embodiments, the test signal is transn1itted at a time other than the expected for the control signal. In some alternative such embodiments, the test signal has a different shape or profile to easily differentiate it from the control signal. This allows for testing the system°s integrity (i.e. if there are any breaks), without involuntarily starting the robotic Working tool, making the robotic working tool believe that there is a functioning boundary when the control signal is transn1itted through a boundary/ guide loop.

In some embodiments, the test signal 125 is the normal control signal 125 that is transmitted during operation of the robotic working tool system 100. This enables for continuous searching for possible breaks.

Figure 3 shows a schematic view of an alternative or additional robotic working tool system as in figure 1 and figure, wherein the robotic lawnmower 130 is arranged with a position detecting sensor, such as a GPS (Global Positioning System) sensor. As a skilled person would understand there exist many different altematives and variations of such sensors, for example RTK (Real-Time Kinetic) sensors, and as such sensors and their use are well-known, no detailed description will be given.

Utilizing a position deterrnining sensor, a map of the work area 105 may be generated. The map may be generated by a user prior to the robotic lawnmower 130 operating in the work area 105, and/or based on information received from the robotic lawnmower 130 during operation in the work area In some such embodiments, the user interface 115, for example through the user interface 215 of the external device 200, is arranged to display the map - or at least a graphical indication of the map. This is shown in figure 3, where also the portion of the boundary wire may be more clearly illustrated. This enables the operator to more fully understand where in the work area the break has been detected, shifting the focus from the boundary wire to the actual work area Retuming to the tables discussed above, in some embodiments, the signal generator is configured to perform resistance measurements even though no break has been detected. This may be utilized in order to ensure that all wires are correctly connected. lf an inconsistency is detected between the measurements received, and the table stored, it is possible that a guide wire or other wire is incorrectly connected.

It should also be noted that even though the examples given herein show the test signal being fed to the left-most Wire connector and received at the right-most Wire connector, the skilled person Would understand that the opposite Would apply equally Well, namely to feed the signal through the right-most Wire connector and receive it at the left-most Wire connector.

Figure 4 shows a floWchart of a general method according to the teachings herein. As disclosed above; the method comprises: transrnitting 410 a test signal 125 through the boundary Wire 120, deterrnining 420 Which of the one or more guide Wires 120G are active for example by measuring the resistance in the guide Wires. Based on Which guide Wires area active (or altematively or additionally Which are inactive) it is possible to determine 430 Which portion B0, B1, B2, BN of the boundary Wire 120 in Which there is a break. ln some embodiments, the portion is indicated visually to the user through a user interface.

This may be initiated after a break has been detected 405. This procedure may also be initiated even if no break has been detected for deterrnining if there is any inconsistency and if so, determine that one Wire is incorrectly connected.

Claims (15)

1. A robotic Working tool system (100) comprising a boundary Wire (120), one or more guide Wires (120G), and a signal generator (114) comprising a controller (111), Wherein the one or more guide Wires (120G) are connected at each one end to the boundary Wire (120) and at the other ends to the signal generator (114), :få and Wherein the controller (111) is H *- ïfåisf: to transmit a test signal (125); deterrnine Which Wires (120G, 120) are active ištsu :v ” and deterrnine Which portion (B0, B 1, B2, BN) of the boundary Wire (120) in Which there is a break os: "wii fïfš

2. The robotic Working tool system (100) according to claim 1, Wherein the controller (111) is further configured to transmit the test signal (125) through the boundary Wire (120).

3. The robotic Working tool system (100) according to claim 1 or 2, Wherein the controller (111) is further configured to transmit the test signal (125) through one of the one or more guide Wires (120G).

4. The robotic Working tool system (100) according to claim 1, 2 or 3, Wherein the controller (111) is further configured to: transmit a second test signal (125) through at least one of the one or more guide Wires (125G); detern1ine Which of the boundary Wire and/or Which of the remaining one or more guide Wires (120G) are active; and determine Which portion (B0, Bl, B2, BN) of the boundary Wire (120) and/or Which of the one or more guide Wires (120G) in

5.Which there is a break.5. The robotic Working tool system (100) according to any preceding claim, Wherein the controller (111) is further configured to: detect that there is a break in the boundary Wire (120) prior to transn1itting the test signal (125) through the boundary Wire.

6. The robotic Working tool system (100) according to any preceding claim, Wherein the controller (111) is further configured to: transmit the test signal (125) through a guide Wire (120G) subsequent to the boundary portion detected to have a break; detern1ine Which of the remaining and subsequent of the one or more guide Wires (120G) that are active; and deterrnine Which portion (B0, B1, B2, BN) of the boundary Wire (120) in Which there is a second break.

7. The robotic Working tool system (100) according to claim 6, Wherein the controller (111) is further configured to detern1ine that there are no more breaks in the boundary Wire (120) if all of the remaining and subsequent of the one or more guide Wires (120G) are active.

8. The robotic Working tool system (100) according to any preceding claim, Wherein the signal generator (114) further comprises a user interface (115), Wherein the controller (111) is configured to display an indication of the portion (B0, B1, B2, BN) of the boundary Wire (120) in Which there is a break in a display portion of the user interface (115).

9. The robotic Working tool system (100) according to claim 8, further comprising an extemal device (200) comprising a user interface (215), Wherein the display portion of the user interface (115) of the signal generator (114) is a display portion of the user interface (215) of the external device (200).

10. The robotic Working tool system (100) according to claim 9, further comprising a robotic Working tool (130) configured to determine its position, Wherein the display portion of the user interface (215) of the external device (200) is configured to display a representation of a map of the Work area, and to display the indication of indication of the portion (B0, Bl, B2, BN) of the boundary Wire (120) in Which there is a break in the representation of the map of the Work area (105).

11. The robotic Working tool system (100) according to any preceding claim, Wherein the controller (111) is further configured to transmit the test signal even if no break is detected, and determine Whether there is any inconsistency in Which guide Wires are active, and if so determine that at least one of the one or more guide Wires is incorrectly connected.

12. The robotic Working tool system (100) according to any preceding claim, Wherein the signal generator (114) is further configured to generate and transmit a control signal (125) through the boundary Wire (120) and Wherein the test signal is the control signal (125).

13. The robotic Working tool system (100) according to any of claims 1 to 10, Wherein the signal generator (114) is further configured to generate and transmit a control signal (125) through the boundary Wire (120) and Wherein the test signal is not the control signal (125).

14. The robotic Working tool system (100) according to any preceding claim, Wherein the robotic Working tool (100) is a robotic laWnmoWer.

15. A method for use in a robotic Working tool system (100) comprising a boundary Wire (120), one or more guide Wires (120G), and a signal generator (114), Wherein the one or more guide Wires (120G) are connected at each one end to the boundary Wire (120) and at the other ends to the signal generator (114), 'vs l>o=t..;=.'§~;:š;:fa.j\fi .t and Wherein the method comprises: a test signal (125); . 1.: ix f. .m S n m f. J to _ e ta,- m « .i ires (120G, 120) are activ deterrnining Which W in ire (120) deterrnining Which portion (BO, B 1, B2, BN) of the boundary W m C r .b a S .1 C r C m h .w m