SE543343C2 - Control signal sensing for a robotic working tool - Google Patents

Abstract

A robotic working tool system comprising a signal generator (215), a signal pick-up (270), a robotic work tool (100) and a controller (216), the controller (216) being configured to receive (410) information from the signal pick-up sensor (270), the information indicating an environment; determine (420) a control signal to be used (235) based on the information indicating the environment; cause the selected control signal (235) to be generated (430) and transmitted (440) to the robotic work tool (100) for controlling the operation of the robotic work tool (100).

Description

CONTROL SIGNAL SENSING FOR A ROBOTIC WORKING TOOL TECHNICAL FIELDThis application relates to robotic Working tools and in particular to asystem and a method for providing an improved control signal sensing for a robotic Working tool, such as a laWnmoWer.

BACKGROUND Automated or robotic power tools such as robotic laWnmoWers are becomingincreasingly more popular. In a typical deployment a Work area, such as a garden, theWork area is enclosed by a boundary cable With the purpose of keeping the roboticlaWnmoWer inside the Work area.

An electric control signal may be transmitted through the boundary cablethereby generating an (electro-) magnetic field emanating from the boundary cable. Therobotic Working tool is typically arranged With one or more (electro-) magnetic sensorsadapted to sense the control signal.

As robotic Work tools are becoming increasingly complex so are their controlsignals, often arrange to carry information to the robotic Work tool. As the control signalsbecome more complicated, a clear reception of the control signal becomes more importantin order to be able to properly receive the transmitted information. As also robotic Worktools are becoming increasingly popular, along With other devices and tools, the (electro-) magnetic surroundings of a garden or other Work area is increasingly filled Withinterference from other robotic Work tool systems or other devices.

Thus, there is a need for an improved manner of enabling a reliable reception of a control signal for a robotic Working tool, such as a robotic laWnmoWer.

SIHVIMARYAs Will be disclosed in detail in the detailed description, the inventors haverealized that a system Where a signal generator is arranged to take into account the surrounding electro-magnetic environment When deterrnining Which control signal to transmit overcomes the drawbacks of the prior art and enables for a reliable receptionthrough a clever selection of control signal.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 asignal generator, a signal pick-up, a robotic work tool and a controller, the controllerbeing conf1gured to receive inforrnation from the signal pick-up sensor, the inforrnationindicating an environment; determine a control signal to be used based on theinforrnation indicating the environment; cause the selected control signal to begenerated and transmitted to the robotic work tool for controlling the operation of therobotic work tool.

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

It is also an object of the teachings of this application to overcome theproblems by providing a method for use in a robotic working tool system comprising arobotic Working tool system comprising a signal generator, a signal pick-up, and arobotic work tool, the method comprising: receiving inforrnation from the signal pick-up sensor, the inforrnation indicating an environment; deterrnining a control signal to beused based on the inforrnation indicating the environment; generating the selectedcontrol signal and transmitting the selected control signal to the robotic work tool forcontrolling the operation of the robotic work tool.

Other features and advantages of the disclosed embodiments will appearfrom the following detailed disclosure, from the attached dependent claims as well asfrom the drawings. Generally, all terms used in the claims are to be interpretedaccording to their ordinary meaning in the technical field, unless explicitly definedotherwise 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 ofany 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 theaccompanying drawings in which: Figure 1A shows an example of a robotic lawnmower according to oneembodiment of the teachings herein; Figure 1B shows a schematic view of the components of an example of arobotic Working tool being a robotic lawnmower according to an example embodimentof the teachings herein; Figure 2 shows an example of a robotic working tool system being a roboticlawnmower system according to an example embodiment of the teachings herein; Figure 3 shows a schematic View of a robotic working tool systemaccording 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 hereinafterwith reference to the accompanying drawings, in which certain embodiments of theinvention are shown. This invention may, however, be embodied in many differentforms 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 befocused on robotic lawnmowers, the teachings herein may also be applied to, roboticball collectors, robotic mine sweepers, robotic farrning equipment, or other roboticworking tools where lift detection is used and where the robotic working tool issusceptible to dust, dirt or other debris.

Figure 1A shows a perspective view of a robotic working tool 100, hereexemplified by a robotic lawnmower 100, having a body 140 and a plurality of wheels130 (only one shown). The robotic lawnmower 100 may comprise charging skids forcontacting contact plates (not shown in figure 1) when docking into a charging station (not shown in figure 1, but referenced 210 in figure 2) for receiving a charging current through, and possibly also for transferring information by means of electricalcommunication between the charging station and the robotic lawnmower 100.

Figure 1B shows a schematic overview of the robotic working tool 100, alsoexemplified here by a robotic lawnmower 100. In this example embodiment the roboticlawnmower 100 is of a mono-chassis type, having a main body part 140. The main bodypart 140 substantially houses all components of the robotic lawnmower 100. The roboticlawnmower 100 has a plurality of wheels 130. In the exemplary embodiment of figure1B the robotic lawnmower 100 has four wheels 130, two front wheels and two rearwheels. At least some of the wheels 130 are drivably connected to at least one electricmotor 150. It should be noted that even if the description herein is focused on electricmotors, combustion engines may altematively be used, possibly in combination with anelectric motor. In the example of figure 1B, each of the wheels 130 is connected to arespective electric motor. This allows for driving the wheels 130 independently of oneanother which, for example, enables steep tuming and rotating around a geometricalcenter for the robotic lawnmower 100. It should be noted though that not all wheelsneed be connected to each a motor, but the robotic lawnmower 100 may be arranged tobe navigated in different manners, for example by sharing one or several motors 150. Inan embodiment where motors are shared, a gearing system may be used for providingthe power to the respective wheels and for rotating the wheels in different directions. Insome embodiments, one or several wheels may be uncontrolled and thus simply react tothe movement of the robotic lawnmower 100.

The robotic lawnmower 100 also comprises a grass cutting device 160, suchas a rotating blade 160 driven by a cutter motor 165. The grass cutting device being anexample of a work tool 160 for a robotic working tool 100. The robotic lawnmower 100also has (at least) one battery 155 for providing power to the motor(s) 150 and/or thecutter motor 165.

The robotic lawnmower 100 also comprises a controller 110 and a computerreadable storage medium or memory 120. The controller 110 may be implementedusing instructions that enable hardware functionality, for example, by using executablecomputer program instructions in a general-purpose or special-purpose processor that may be stored on the memory 120 to be executed by such a processor. The controller 110 is configured to read instructions from the memory 120 and execute theseinstructions to control the operation of the robotic lawnmower 100 including, but notbeing limited to, the propulsion of the robotic lawnmower. The controller 110 may beimplemented using any suitable, available processor or Programmable Logic Circuit(PLC). The memory 120 may be implemented using any commonly known technologyfor computer-readable memories such as ROM, RAM, SRAM, DRAM, FLASH, DDR,SDRAM or some other memory technology.

The robotic lawnmower 100 may further be arranged with a wireless com-munication interface 115 for communicating with other devices, such as a server, apersonal computer or smartphone, or the charging station. Examples of such wirelesscommunication devices are Bluetooth®, WiFi® (IEEE802.l lb), Global System Mobile(GSM) and LTE (Long Term Evolution), to name a few.

For enabling the robotic lawnmower 100 to navigate with reference to aboundary cable emitting a magnetic field caused by a control signal transmitted throughthe boundary cable, the robotic lawnmower 100 is further configured to have at leastone magnetic field sensor 170 arranged to detect the magnetic field (not shown) and fordetecting the boundary cable and/or for receiving (and possibly also sending)information to/ from a signal generator (will be discussed with reference to figure 2). Insome embodiments, the sensors 170 may be connected to the controller ll0, possiblyvia filters and an amplifier, and the controller ll0 may be configured to process andevaluate any signals received from the sensors 170. The sensor signals are caused by themagnetic field being generated by the control signal being transmitted through theboundary cable. This enables the controller l 10 to determine whether the roboticlawnmower 100 is close to or crossing the boundary cable, or inside or outside an areaenclosed by the boundary cable.

In one embodiment, the robotic lawnmower 100 may further comprise atleast one beacon navigation sensor and/or a satellite navigation device 175. The beaconnavigation device may be a Radio Frequency receiver, such as an Ultra Wide Band(UWB) receiver or sensor, configured to receive signals from a Radio Frequency beacon, such as a UWB beacon. The beacon navigation device may be an optical receiver configured to receive signals from an optical beacon. The satellite navigationdevice may be a GPS (Global Positioning System) device.

Figure 2 shows a schematic view of a robotic Working tool system 200 inone embodiment. The schematic view is not to scale. The robotic working tool system200 comprises a charging station 2l0 having a signal generator 2l5 and a roboticworking tool l00. As with figures lA and lB, the robotic working tool is exemplifiedby a robotic lawnmower, whereby the robotic working tool system may be a roboticlawnmower system or a system comprising a combinations of robotic working tools,one being a robotic lawnmower, but the teachings herein may also be applied to otherrobotic working tools adapted to operate within a work area.

The signal generator is arranged to generate a control signal 235. To perform this, the signal generator is arranged with a controller and memory module 2l6.

The controller and memory module 2l6 operates and functions in the same manner asthe controller ll0 and memory l20 of the robotic working tool l00. The controller andmemory module 2l6 may also be the controller and memory module of the chargingstation, hereafter simply referred to as the controller 2l6.

In one altemative or additional embodiment the controller and memorymodule 2l6 may also comprise or be connected to a communication interface (notshown explicitly but considered to be part of the controller and memory module). Thecommunication interface is enabled for communicating with other devices, such as a server, a personal computer or smartphone, a robotic working tool l00, another signal generator 2l5 or another charging station 2l0 using a wireless communication standard.

Examples of such wireless communication standards are Bluetooth®, WiFi®(IEEE802.l lb), Global System Mobile (GSM) and LTE (Long Term Evolution), toname a few.

In one such embodiment where the charging station 2l0 is arranged with acommunication interface, the charging station 2l0 is conf1gured to establish contactwith the robotic working tool l00 and query the robotic working tool l00 for details,such as signal characteristics, on the control signal being used. As would be apparent toa skilled person, the manner of establishing such a connection differs depending on the Radio Access Technology or wireless communication standard used but generally includes the steps of sensing a presence of the robotic Working tool, sending anidentifying signal, requesting a connection to be established, establishing theconnection, sending a query and receiving a response. In such an embodiment, thecharging station 210 is thus configured to simply query the robotic Working tool fordetails on the used control signal. However, this requires that a specially adapted roboticWorking tool 100 is utilized.

In an alternative or additional such embodiment Where the charging station210 is arranged With a communication interface, the charging station 210 is conf1guredto establish contact With an extemal server, such as through a cloud service, and querythe extemal server for details on the control signal being used.

The robotic Working tool system 220 also comprises a boundary cable 230arranged to enclose a Work area 205, in Which the robotic laWnmoWer 100 is supposedto serve. The control signal 235 is transmitted through the boundary cable 230 causing amagnetic field (not shown) to be emitted.

In one embodiment the control signal 235 is a sinusoid periodic currentsignal. In one embodiment the control signal 235 is a pulsed current signal comprising aperiodic train of pulses. In one embodiment the control signal 235 is a coded signal,such as a CDMA signal.

The robotic Working tool system 220 may also optionally comprise at leastone beacon 220 to enable the robotic laWnmoWer to navigate the Work area using thebeacon navigation sensor(s) 175.

The Work area 205 is in this application exemplified as a garden, but canalso be other Work areas as Would be understood. The garden contains a number ofobstacles (O), exemplified herein by a number (3) of trees (T) and a house structure (H).The trees are marked both With respect to their trunks (filled lines) and the extension oftheir foliage (dashed lines).

As can be seen in figure 2, the boundary cable 230 has been laid so that so-called islands are formed around the trees" trunks and the house (H). This requires thatmore boundary cable is used, than if the Work area Was Without such obstacles. It shouldbe noted that any distances between cables are greatly exaggerated in this application in order to make the distances visible in the draWings. In a real-life installations the boundary cable is usually laid so that there is not distance between the cable going outand the cable coming back (distance = 0).

As an electrical signal is transmitted through a cable, such as the controlsignal 235 being transmitted through the boundary cable 230, a magnetic field isgenerated. The magnetic field may be detected using field sensors, such as Hall sensors.A sensor - in its simplest forrn -is a coil surrounding a conductive core, such as aferrite core. The amplitude of the sensed magnetic field is proportional to the derivate ofthe control signal. A large variation (fast and/or of great magnitude) results in a highamplitude for the sensed magnetic field.

The Variations are sensed and compared to a reference signal or pattem ofVariations in order to identify and thereby reliably sense the control signal.

As the sensors react to changes in the (electro-) magnetic field they may bechanges to other influences or interferences. Especially if one control signal coincides,at least partially, With a reoccurring interference, the sensed magnetic field Will notcorrespond to the reference signal and the control signal Will not be properly or reliablysensed.

The inventors have realized that instead of simply seemingly randomlyselecting a control signal, or by selecting a control signal based on an allocation ofrobotic Work tool systems, a signal pick up or sensor 270 is configured to be used by thecharging station 2l0. The signal pick-up 270 may be arranged as a part comprised in thecharging station, or in the signal generator 2l5 or as a standalone device that isconnected to the charging station 2l0, or to the signal generator 2l5.

In one embodiment, and in its simplest form, the signal pick-up 270 is amagnetic field sensor, for example a conductive core (such as a ferrite core) surroundedby a coil.

The signal pick-up 270 is thus configured to sense (electro-) magneticfields. Depending on the placement of the signal pick-up 270, the signal pick-up 270Will sense the (electro-) magnetic environment at that placement.

For the purpose of this application it Will be assumed that it is the signalgenerator 2l5 that deterrnines Which control signal that should be utilized, hoWever, it may be a controller of the charging station or other controller located or connected thereto. For the purpose of clarity, all such possible controllers will be assumed to be atleast part of the charging station"s controller 216. The controller 216 of the chargingstation 210 will thus be configured to receive a measurement of the (electro-) magneticenvironment presumably of the work area 205. Based on the measurement, different (ifany) interfering signal components may be identified in the environment and based onthe knowledge of the interfering signal components an optimum or best choice ofcontrol signal 235 may be selected to be used by the signal generator 215.

A control signal may be selected or be deterrnined based on a choice of aplurality of available options. A signal may be selected or deterrnined by beingcalculated based on the information. A signal may thus be selected to be deterrnined orcalculated and no difference will be made between to select or to determine a controlsignal unless otherwise indicated herein.

In one embodiment, the controller of the signal generator is configured todetermine a regularity of the environment and adapt a timing of the control signal basedon the regularity so that the control signal 235 is transmitted when there is the leastinterference. For example if the signal pick-up 270 senses a regularly reoccurring signal,such as a control signal 235-2 of a neighbouring system, being transmitted in specifictime windows, i.e. in a first time window, the control signal 235 of the roboticlawnmower system 200 is selected so that its time window for transmission does notoverlap the neighbouring signal°s time window, i.e. the control signal 235 is transmittedin a second time window.

In one embodiment, the controller 216 of the charging station is configuredto determine a characteristic of the environment and adapt a characteristic of the controlsignal based on the characteristic of the environment. In one such embodiment thecharacteristic of the environment is a frequency or coding scheme of neighbouringsignals, whereby the characteristic of the control signal is a frequency or coding schemethat allows for reliable reception, such as simply selecting a different frequency. In onesuch embodiment, where the environment characteristics represents a noise type, acoding scheme known to overcome or to be reliably used in such noise situations, i.e. associated with the noise situation, is selected for the control signal 235.

In one embodiment, the controller 216 is configured to receive the sensedenvironment and deterrnine a control signal 235 at start-up of the robotic lawnmowersystem 200.

In one embodiment, the controller 216 is configured to receive the sensedenvironment and deterrnine a control signal 235 at start-up of the robotic lawnmower100 such as prior to perforrning a scheduled or otherwise initiated operation session.

In one embodiment, the controller 216 is configured to receive the sensedenvironment continuously, regularly or repeatedly and if it is deterrnined that theenvironment has changed suff1ciently enough to warrant a new control signal beingselected, the controller 216 deterrnines a new control signal 235.

A new or second control signal may be needed for example if it isdeterrnined that a new (reoccurring) signal overlapping the control signal is detected. Anew control signal may be needed for example if it is deterrnined that a new(reoccurring) signal having a frequency overlapping or coinciding the frequency of thecontrol signal is detected. A new control signal may be needed for example if it isdeterrnined that new noise changing the overall environment is detected.

In one embodiment the new control signal 235 is communicated to therobotic lawnmower 100 before the robotic lawnmower system 200 switches to the new(or second) control signal 235 from the previous (or first) control signal 235. In oneembodiment the new control signal 235 is communicated to the robotic lawnmower 100before start of another operating session.

The signal pick-up 270 may be located inside or adj acent the chargingstation for sensing the environment in the vicinity of the charging station. Altemativelyor additionally, the signal pick-up 270 may be arranged to be movable or removablyattached or connected to the charging station (either wired or wirelessly in which case,the signal pickup comprises a communication interface for communicating with thecharging station 210). The movable signal pick-up 270 may then be located at differentlocations for deterrnining the (electro-) magnetic environment at a location remote fromthe charging station 210.

In one embodiment, the control signal 235 is selected so that it cancels out a deterrnined signal in the environment. As signal may be cancelled out by transmitting ll the opposite or reversed signal (or depending on the direction of corresponding cablespropagating the electric signals, transmit the same signal) whereby the magnetic fieldsgenerated by the two signals will cancel each other out.

In one such embodiment, a movable signal pick-up 270 may be locatedadj acent a neighbouring robotic lawnmower system, whereby the borders between thetwo systems will be cancelled out thus generating an aggregate work area comprisingthe work area and the first robotic lawnmower system and the work area of the secondor neighbouring robotic lawnmower system. Figure 3 shows an example of where suchan embodiment could be used to sense the control signal 235-2 of the neighbouringsystem 200-2 to cancel it out enabling the robotic lawnmower l00 to operate freelywithin both the work area 205 of the robotic lawnmower system 200 as well as the workarea 205-2 of the neighbouring system 200-2.

Figure 3 shows a schematic View of an example embodiment of a roboticworking tool system 200. The robotic work tool system 200 is in this example a roboticlawnmower system 200 as disclosed in figure 2. The work area 205 of the roboticlawnmower system 200 of figure 3 is subjected to Various sources of interfering(electro-) magnetic radiation such as arising from a neighbouring system 200-2 and/orone or several disturbing sources 300, in this example two are shown 300-l and 300-2.Such disturbing sources 300 may be stationary or temporary. Examples of disturbingsources 300 are mobile network antennas, mobile communications devices (such assmartphones). The exact nature of the disturbing sources is not important, suff1ce thatthe disturbing source emit (electro-) magnetic radiation that may interfere with thesensing of the control signal, either by causing interference or noise, or by simplycolliding in time with the control signal, thereby corrupting the control signal 235.

In the example of figure 3, the robotic lawnmower system 200 and theneighbouring system 200-2 both are arranged to transmit a control signal 235-l and235-2 respectiVely each possibly carrying information such as an identifier IDl and ID2respectively. As a skilled person would realize, not only can the robotic lawnmowersystem 200 be disturbed by the neighbouring system 200-2, but the neighbouringsystem 200-l may also be disturbed by the robotic lawnmower system 200. 12 In this example the boundary cable 230-2 of the neighbouring system 200-lis laid so that it is adjacent the first boundary cable 230-l at least along a portion of itslength. This gives rise to an area Where the (electro-) magnetic field emanating from theneighbouring control signal 235-2 Will be sensed in the Work area 205 of the roboticlaWnmoWer l00 in the robotic laWnmoWer system 200.

As has been disclosed in the above, if the control signal 235 is selected sothat it cancels out the control signal 235-2 of the neighbouring system, the roboticlaWnmoWer l00 Will be enabled to operate freely in the aggregated Work area thusforrned by the Work area 205 of the robotic laWnmoWer system 200 and the Work area205-2 of the neighbouring system 200-2.

The first disturbing source 300-l also gives rise to an area Where the(electro-) magnetic field emanating from the disturbing source 300-l Will be sensed inthe Work area 205 of the robotic laWnmoWer l00 in the robotic laWnmoWer system 200and the same applies for the second disturbing source 300-2.

As can be seen, there may be different areas AX Where the roboticlaWnmoWer l00 Will be subjected to different (electro-magnetic interferences. In theexample of figure 3, there are five such areas. A first area Al is the main Work area. Asecond area A2 is Where the control signal 235-2 of the neighbouring system 200-2 Willbe sensed. A third area A3 is Where the first disturbing source 300-l Will be sensed. Afourth area A4 is Where the second disturbing source 300-2 Will be sensed. And a fifthare A5 Where the first disturbing source 300-l and the second disturbing source 300-2Will be sensed.

The inventors have realized that in order to enable the robotic laWnmoWerl00 to adapt to these varying environments, the signal pickup 270 may be utilized tosense the different areas, and adapt the control signal 235 accordingly. The signal pickup may thus be moved over the Work area 205 and as an area AX of a (electro-)magnetic environment is sensed and a corresponding control signal 235 deterrnined, thatcontrol signal 235 may be associated With that area AX. For example a first controlsignal 235 is associated With the first area Al, a second control signal 235 is associatedWith the second area A2, a third control signal 235 is associated With the third area A3,a fourth control signal 235 is associated With the fourth area A4 and a fifth control 13 signal 235 is associated With the f1fth area A5. It should be noted that not all controlsignals have to be different and may also vary in time, as the environment of thecorresponding area varies.

A control signal may be associated With an area in different manners. In oneembodiment, the area AX may be identified through coordinates and the control signalthus also associated With those coordinates. The coordinates may be deduced reckoningcoordinates or control points. Altematively or additionally the coordinates may be GPScoordinates. Altematively or additionally the coordinates may be deterrnined based onbeacons, such as RF or UWB beacons. Altematively or additionally the coordinatesmay be deterrnined based on a timed scheduling of the robotic laWnmoWer°s operation.Altematively or additionally the coordinates may be deterrnined based on thesurrounding environment, for example such as sensed by the sensor(s) 170 of therobotic laWnmoWer 100.

In one embodiment the signal pick-up 270 may be Walked around the Workarea 205 by a user for sensing the environment(s) around the Work area 205 andidentifying various areas AX.

In one embodiment the signal pick-up 270 may be attached to and carriedaround the Work area 205 by the robotic laWnmoWer 100 for sensing the environment(s)around the Work area 205 and identifying various areas AX.

In one embodiment, the sensor 170 of the robotic laWnmoWer is utilized bythe charging station as the signal pick-up 270, Whereby the sensing information receivedfrom the signal pickup 270 (being the sensor 170 of the robotic laWnmoWer) iscommunicated either r raW or at least partially processed to the charging station possiblyfor further processing.

In one such embodiment, the controller 110 of the robotic laWnmoWerperforrns some or all of the operations discussed here to be performed by the controller216 of the charging station, the controller 110 of the robotic laWnmoWer 100 thuseffectively being the controller 216 of the charging station 210.

In an altemative or additional such embodiment the signal pick-up 270 isthus the sensor(s) 170 of the robotic laWnmoWer 100, and the robotic laWnmoWer is configured to may carry the sensor 170 around the Work area 205 for sensing the 14 environment(s) around the Work area 205 and identifying various areas AX. This maybe done as part of a start-up or initialization routine. Altematively or additionally it maybe done While operating in the Work area 205.

In such embodiments, the controller (of the charging station and/or of therobotic laWnmoWer) is thus configured to associate a control signal With an area andswitch to the control signal as the associated area is entered by the robotic laWnmoWer1 00.

Figure 4 shows a flowchart of a general method according to the teachingsherein. A controller 216 (or 110) receives 410 information from a signal pick-up sensor270 (or 170), the information indicating a (electro-) magnetic environment. Thecontroller 216 deterrnines 420 a control signal based on the information indicating the(electro-) magnetic environment and causes the selected control signal to be generated430 and transmitted 440 to a robotic laWnmoWer 100 for controlling the operation of therobotic laWnmoWer 100.

Even though the teachings herein have been focussed on detecting a(electro-) magnetic environment and transmitting a control signal through a boundarycable, the same teachings may apply to selecting a control signal to be transmittedthrough beacons, such as RF or UWB beacons or other RF interface, such as through the communication interface.

Claims (17)

1. A robotic Working tool system (200) comprising a signal generator (215)and a robotic Work tool (100), the robotic Working tool system (200) beingcharacterized in that the signal generator (215) includes a signal pick-up sensor (270),and a controller (216), the controller (216) being conf1gured to receive (410) inforrnation from the signal pick-up sensor (270), theinforrnation indicating an environment; deterrnine (420) a control signal to be used (235) based on the informationindicating the environment; cause the selected control signal (235) to be generated (430) and transmitted(440) to the robotic Work tool (100) for controlling the operation of the robotic Worktool (1 00).

2. The robotic Working tool system (200) according to claim 1, Wherein the controller (216) is configured to deterrnine the control signal (235) on a startup.

3. The robotic Working tool system (200) according to claim 1 or 2, Whereinthe controller (216) is configured to deterrnine the control signal (235) during operation of the robotic Work tool (100).

4. The robotic Working tool system (200) according to any preceding claim,Wherein the controller (216) is configured to deterrnine a regularity of the environmentand adapt a timing of the control signal (235) based on the regularity so that the control signal (235) is transmitted When there is the least interference.

5. The robotic Working tool system (200) according to claim 4, Wherein thecontroller (216) is configured to sense a signal being transmitted in a first time Window,and deterrnine the control signal (235) so that the control signal (235) is transmitted in a second time Window. 16

6. The robotic Working tool system (200) according to any preceding claim,Wherein the controller (216) is conf1gured to deterrnine a characteristic of theenvironment and adapt a characteristic of the control signal (235) based on the characteristic of the environment.

7. The robotic Working tool system (200) according to claim 6, Wherein thecharacteristic of the environment is a frequency of a neighbouring signal and thecontroller (216) is conf1gured to selecting a different frequency for the control signal (235).

8. The robotic Working tool system (200) according to claim 6 or 7, Whereinthe characteristic of the environment is a coding scheme a neighbouring signal and the controller (216) is configured to select a coding scheme for the control signal (235).

9. The robotic Working tool system (200) according to claim 6, 7 or 8,Wherein the characteristic of the environment is a noise situation and the controller(216) is configured to select a coding scheme associated With the noise situation for the control signal (235).

10. The robotic Working tool system (200) according to any precedingclaim, Wherein the signal pick-up sensor (270) is comprised in the charging station(2 1 0).

11. The robotic Working tool system (200) according to any precedingclaim, Wherein the signal pick-up sensor (270) is movable, and When dependent on claim 10, removable from the charging station (210).

12. The robotic Working tool system (200) according to any precedingclaim, Wherein the signal pick-up sensor (270) is arranged to be moved around a Workarea (205) of the robotic Working tool system (200) to sense and provide information on the environment in at least one area (AX) of the Work area (205), Wherein the controller 17 (216) is further configured to determine the control signal (235) to be associated With at least one of the at least one area (AX).

13. The robotic Working tool system (200) according to any precedingclaim, Wherein the controller (216) is further configured to: deterrnine a second signal in the environment and deterrnine the control signal (235) to cancel out the deterrnined second signal in the environment.

14. The robotic Working tool system (200) according to claim 13, Whereinthe second signal is a control signal (235-2) of a neighbouring robotic Work tool system (zoo-z).

15. The robotic Working tool system (200) according to any precedingclaim, Wherein the robotic Working tool system (200) further comprises a boundarycable (230), and Wherein the signal pick-up sensor (270) is a magnetic sensor and theinformation indicating the environment indicates a (electro-) magnetic environment, andWherein the controller (216) is further configured to transmit the control signal (235)through the boundary cable (23 0).

16. The robotic Working tool system (200) according to any preceding claim Wherein the robotic Work tool (100) is a robotic laWnmoWer (100).

17. A method for use in a robotic Working tool system (200) comprising asignal generator (215) and a robotic Work tool (100), the method being characterized inthat the signal generator (215) includes a signal pick-up sensor (270), and in that themethod comprises the signal generator performing: receiving (410) information from the signal pick-up sensor (270), the information indicating an environment; 18 deterrnining (420) a control signal to be used (235) based on the informationindicating the environment;generating (430) the selected control signal (235) andtransniitting (440) the selected control signal (235) to the robotic Work tool5 (l00) for controlling the operation of the robotic Work tool (l00).