SE2150193A1 - Adaptable operation for a robotic work tool, such as a robotic lawn mower - Google Patents

Abstract

A robotic working tool system (200) comprising a robotic working tool (100) comprising a controller (110) and at least one collision detector (175), wherein the controller (110) is configured to: receive information from the at least one collision detector (175) indicating a collision event; interpret the collision event as an operator command associated with the collision event; and to execute the operator command.

Description

ADAPTABLE OPERATION FOR A ROBOTIC WORK TOOL, SUCH AS AROBOTIC LAWN MOWER TECHNICAL FIELD This application relates to robotic Work tools, such as robotic laWn mowers,and in particular to a system and a method for providing a robotic Work tool, such as a laWn moWer, having an adaptable operation.

BACKGROUNDThe inventors have realized that there is a problem in that as the robotic laWn moWer l00 is automatic, it is difficult for the robotic laWn moWer l00 to predictthe needs, desires or actions of the operator and act accordingly. Many contemporaryrobotic laWn mowers have a user interface, for example based on a smartphone, basedon a control panel of the robotic laWn moWer l00, or based on a control panel of thecharging station 210. HoWever, using such user interfaces is difficult and cumbersomeWhen Working in an area such as a garden as it requires that the user interface isproduced (such as Walking over to the charging station or carrying the smart phone) andit requires that the operator is able to engage With the user interface, such as putting down any tools and removing gloves.

SUMMARY According to an aspect it is an object of the teachings of this application toovercome the problems by providing robotic Working tool system comprising a roboticWorking tool comprising a controller and at least one collision detector, Wherein thecontroller is configured to: receive information from the at least one collision detectorindicating a collision event; interpret the collision event as an operator commandassociated With the collision event; and to execute the operator command .

In one embodiment the robotic Work tool comprises an outer shell and Wherein the collision event is generated by an operator engaging the outer shell.

In one embodiment the collision event is indicative of a single collision,such as a forwards or rearwards collision.

In one embodiment the associated command is one taken from the groupcomprising to stop if in movement, to initiate movement if not in movement or toactivate/deactivate a work tool or attachment.

In one embodiment the collision event is indicative of a series of collisions,such as a forwards-forwards collision or rearwards-rearwards collision.

In one embodiment the associated command is one taken from the groupcomprising to change direction, to retum to a specific location, to initiate a specificnavigation mode.

In one embodiment the robotic Working tool is a robotic lawn mower.

According to the another aspect it is also an object of the teachings of thisapplication to overcome the problems by providing a method for use in a roboticworking tool system comprising a robotic working tool comprising at least one collisiondetector, the method comprising: receiving information from the at least one collisiondetector indicating a collision event; interpreting the collision event as an operatorcommand associated with the collision event; and to executing the operator command.

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 the accompanying drawings in which: Figure 1A shoWs an example of a robotic Working tool according to oneembodiment of the teachings herein; Figure 1B shows a schematic vieW of the components of an example of arobotic Working tool according to an example embodiment of the teachings herein; Figure 2 shoWs an example of a robotic Working tool system being a roboticlaWn moWer system according to an example embodiment of the teachings herein; Figure 3 shoWs an example of a robotic Working tool being a robotic laWnmoWer according to an example embodiment of the teachings herein; 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.

Figure 1A shoWs a perspective vieW of a robotic laWn moWer 100, having abody 140 and a plurality of Wheels 130 (only a front Wheel and a rear Wheel is shoWn).The robotic laWn moWer 100 may be a multi-chassis type, as in figure 1A, or a mono-chassis type (as in figure 1B). A multi-chassis type comprises more than one bodychassis that are movable With respect to one another. A mono-chassis type comprisesonly one main chassis, comprising a shell and a hull (see figure 1B).

The robotic laWn moWer 100 may comprise charging skids for contactingcontact plates (not shoWn in figure 1A) When docking into a charging station (notshoWn in figure 1A, but referenced 210 in figure 2) for receiving a charging currentthrough, and possibly also for transferring information by means of electricalcommunication betWeen the charging station and the robotic laWn moWer 100.

Figure 1B shoWs a schematic overview of the robotic Working tool hereexemplified by a robotic laWn moWer 100. In this example embodiment the robotic laWn moWer 100 is of a mono-chassis type, having a main chassis 140. The main chassis 140 substantially houses all components of the robotic lawn mower 100. Therobotic lawn mower 100 has a plurality of wheels 130. In the exemplary embodiment offigure 1B the robotic lawn mower 100 has four wheels 130, two front wheels 130a andtwo rear wheels 130b. In the embodiment shown in figure 1B, the front wheels 130a hasa smaller diameter than the rear wheels 130b. At least some of the wheels 130 aredrivably connected to at least one electric motor 150. It should be noted that even if thedescription herein is focused on electric motors, combustion engines may altemativelybe used, possibly in combination with an electric motor. In the example of figure 1B,each of the wheels 130 is connected to a respective electric motor. This allows fordriving the wheels 130 independently of one another which, for example, enables steeptuming and rotating around a geometrical centre for the robotic lawn mower 100. Itshould be noted though that not all wheels need be connected to each a motor, but therobotic lawn mower 100 may be arranged to be navigated in different manners, forexample by sharing one or several motors 150. In an embodiment where motors areshared, a gearing system may be used for providing the power to the respective wheelsand for rotating the wheels in different directions. In some embodiments, one or severalwheels may be uncontrolled and thus simply react to the movement of the robotic lawnmower 100.

The robotic lawn mower 100 also comprises a grass cutting device 160,such as a rotating blade 160 driven by a cutter motor 165. The grass cutting devicebeing an example of a work tool 160 for a robotic lawn mower 100. The robotic lawnmower 100 also has (at least) one battery 155 for providing power to the motor(s) 150and/or the cutter motor 165.

The robotic lawn mower 100 also comprises a controller 110 and acomputer readable storage medium or memory 120. The controller 110 may beimplemented using instructions that enable hardware functionality, for example, byusing executable computer program instructions in a general-purpose or special-purposeprocessor 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 executethese instructions to control the operation of the robotic lawn mower 100 including, but not being limited to, the propulsion of the robotic lawn mower. 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 technologyfor computer-readable memories such as ROM, RAM, SRAM, DRAM, FLASH, DDR,SDRAM or some other memory technology.

The robotic laWn moWer 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, the charging station, and/or other robotic Workingtools. Examples of such Wireless communication devices are Bluetooth®, WiFi®(IEEE802.11b), Global System Mobile (GSM) and Long Term Evolution (LTE), toname a few.

For enabling the robotic laWn moWer 100 to navigate With reference to aboundary Wire emitting a magnetic field caused by a control signal transmitted throughthe boundary Wire, the robotic laWn moWer 100 is further configured to have at least onemagnetic field sensor 170 arranged to detect the magnetic field (not shoWn) and fordetecting the boundary Wire 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 110, possiblyvia filters and an amplifier, and the controller 110 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 Wire. This enables the controller 110 to determine Whether the robotic laWnmoWer 100 is close to or crossing the boundary Wire, or inside or outside an areaenclosed by the boundary Wire.

In an altemative or supplemental embodiment, to enable the robotic laWnmoWer 100 to operate and navigate according to a virtual map possibly stored in thememory module 120, the robotic laWn moWer 100 may further comprise at least onenavigation sensor, such as a beacon navigation sensor and/or a satellite navigationsensor 190. The beacon navigation sensor may be a Radio Frequency receiver, such asan Ultra Wide Band (UWB) receiver or sensor, configured to receive signals from aRadio Frequency beacon, such as a UWB beacon. Altematively or additionally, the beacon navigation sensor may be an optical receiver configured to receive signals from an optical beacon. The satellite navigation sensor may be a GPS (Global PositioningSystem) device or other Global Navigation Satellite System (GNS S) device.

The robotic lawn mower 100 may further optionally comprise one or moresensors for deduced navigation 180. Examples of sensors for deduced reckoning areodometers, accelerometers, gyroscopes, and compasses to mention a few examples.Deduced navigation sensors may enable operation relative a boundary wire and/orenable operation relative a stored map.

In embodiments, where the robotic lawn mower 100 is arranged with anavigation sensor, the magnetic sensors 170 are optional.

The robotic lawn mower 100 may also comprise one or more collisiondetectors 175. In the example of figure 1B, the robotic lawn mower 100 comprises afront collision detector 175-1, enabling the robotic lawn mower 100 to detect a collisionwhile moving in a forwards direction, i.e. a forwards collision, and a rear collisiondetector 175-2, enabling the robotic lawn mower 100 to detect a collision while movingin a reverse direction, i.e. a reverse collision. In one embodiment, the collision detectoris arranged to operate by sensing a relative movement between an outer shell 140-2 orother body part of the robotic lawn mower, and an inner hull 140-1 or other body part ofthe robotic lawn mower. The collision is configured to detect a relative movement, anddepending on the relative movement (such as direction, amplitude and/or force) of thedetected relative movement, determine if a collision (front, back or side) was detectedor possibly that another event was detected, and based on the deterrnination, the roboticlawn mower 100 is configured to take appropriate action. An example of an appropriateaction for a collision event is for example to tum away and move away from theposition where the collision was detected. The collision detector 175 may, in oneembodiment, be arranged to also operate as a lift detector. An upwards or downwardsrelative movement may be indicative of the robotic lawn mower 100 being lifted. Anyaccelerometer or gyroscope (as part of deduced reckoning means that will be discussedbelow) may be utilized as lift detectors. Altematively, the robotic lawn mower 100comprises specific lift detectors 176. An example of an appropriate action for a liftevent is for example to disengage or stop the grass cutting device 160 and to stop the wheels 130.

Figure 2 shows a schematic View of a robotic laWn moWer system 200 inone embodiment. The schematic View is not to scale. The robotic laWn moWer system200 comprises a robotic laWn mower 100 as in figures 1A and 1B.

The robotic laWn moWer system 200 may also comprise charging station210 Which in some embodiments is arranged With a signal generator 215 and aboundary Wire 220.

The signal generator 215 is arranged to generate a control signal 225 to betransmitted through the boundary Wire 220. The boundary Wire 220 is arranged toenclose a Work area 205, in Which the robotic laWn moWer 100 is supposed to serve.The control signal 225 transmitted through the boundary Wire 220 causes a magneticfield (not shown) to be emitted. In one embodiment the control signal 225 is a sinusoidperiodic current signal. In one embodiment the control signal 225 is a pulsed currentsignal comprising a periodic train of pulses. In one embodiment the control signal 225 isa coded signal, such as a CDMA signal.

As an electrical signal is transmitted through a Wire, such as the controlsignal 225 being transmitted through the boundary Wire 220, a magnetic field isgenerated. The magnetic field may be detected using field sensors, such as Hall sensors.A sensor - in its simplest form -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 areference signal or pattem of Variations in order to identify and thereby reliably sensethe control signal.

The robotic laWn moWer system 200 may also optionally or altematiVely tothe boundary Wire 220 comprise at least one beacon 230 to enable the robotic laWnmoWer to naVigate the Work area using the beacon naVigation sensor(s) 190 as discussedin the aboVe. In an embodiment, Where the robotic laWn moWer 100 is arranged tonaVigate or operate according to a Virtual map, the boundary Wire 220 and the signalgenerator 215 are optional.

The Work area 205 is in this application exemplified as a garden, but can also be other Work areas as Would be understood. The garden contains a number of features, exemplified herein by a number (3) of trees (T), a compost heap (C), a flowerbed (f) and a house structure (H). The trees are marked both with respect to their trunks(filled lines) and the extension of their foliage (dashed lines).

As can be seen in figure 2, the boundary wire 220 has been laid so that so-called islands are forrned around the trees" trunks (T) and the house (H) and flower bed(f)- As mentioned in the background section, the inventors have realized thatthere is a problem in that as the robotic lawn mower 100 is automatic, it is difficult forthe robotic lawn mower 100 to predict the needs, desires or actions of the operator andact accordingly. Many contemporary robotic lawn mowers have a user interface, forexample based on a smartphone, based on a control panel of the robotic lawn mower100, or based on a control panel of the charging station 210. However, using such userinterfaces is difficult and cumbersome when working in an area such as a garden as itrequires that the user interface is produced (such as walking over to the charging stationor carrying the smart phone) and it requires that the operator is able to engage with theuser interface, such as putting down any tools and removing gloves.

The inventors have therefore realized after insightful and inventivereasoning that an altemative command interface may be provided utilizing the collisiondetector 175 of the robotic lawn mower 100. The inventors have realized that such acollision-based command interface may be provided by adapting the operation of therobotic lawn mower 100 so that a detected collision event is interpreted as a commandand not a collision. This enables the operator to engage with the outer shell 140-2 of therobotic lawn mower 100 in order to provide a command to the robotic lawn mower 100.The robotic lawn mower 100 is thus conf1gured to receive a detection of a collisionevent and to interpret the collision event as a command, or execute a commandassociated with the detected collision event.

Figure 3 shows a schematic view of a series of events involving a roboticlawn mower 100 and an operator. In the upper scenario the robotic lawn mower 100 istravelling in a forwards motion as indicated by the arrow marked FM. As the roboticlawn mower 100 comes into close range of the operator, the operator may engage the robotic lawn mower 100, for example with a rake, a shovel or other tool, to provide a command. The operator engages the robotic lawn mower 100 so as to generate acollision event which is reinterpreted by the controller of the robotic lawn mower 100 asthe intended command. The middle scenario of figure 4, shows how the operatorengages the robotic lawn mower 100 with the tool. The engagement may be to affect theouter shell to register a collision event. The collision event is detected by the collisiondetector 175 and in this embodiment the associated and intended command is a STOPcommand, whereby the controller 110 causes the robotic lawn mower 100 to stop(which is indicated by no movement arrow being shown for the middle scenario). In thelower scenario of figure 4, the operator has again engaged the robotic lawn mower 100to generate a collision event associated with an intended command, and in this examplethe robotic lawn mower 100 has resumed its forwards movement (as indicated by thearrow marked FM), possibly in a follow-me function.

In one example, a detection of forward-collision-event is reinterpreted orrecoded as being a first command. The first command may be to stop, in particular if therobotic lawn mower 100 is currently moving. Altematively, the first command may beto propel forwards and/or to follow the operator), in particular if the robotic lawnmower 100 is currently not moving (i.e. has stopped). The command associated with thedetected collision event may thus be dependent on the current operation.

Likewise, a detection of rear-collision-event may be reinterpreted or recodedas being a second command. For example a rear-collision-event may be interpreted as aretum to charging station command (or other function).

The operator may thus enabled to for example tap the robotic lawn mower100 in the front with the operator°s foot or a tool (such as a rake) to toggle operationbetween propelling forwards and stopping). Likewise, the operator may be enabled tofor example tap the robotic lawn mower 100 in the rear to cause the robotic lawn mowerto retum to a tipping location (such as the compost heap). And, all without having totake of any gloves, put down tools or generally interrupt the current work of theoperator.

Examples of collision events and associated commands are: Front collision - TOGGLE STOP/FORWARD Rear collision - PERFORM COMMAND (such as dumping) The collision-based command interface may be part of an adaptation of theOperating in the attachment mode. The associated command may thus be dependent onthe attachment.

The collision-based command interface may also be utilized in the normaloperation, i.e. the operation in the lawn mower mode. To enable the robotic lawn mower100 to still be able to detect normal collisions, the robotic lawn mower should bearranged to detect further collision events, such as a series of events. A collision event,may thus be detected only after a series of sensor event have been detected. Forexample, a double-front-collision-event (two actuations in series of the forwardscollision detector 175) is associated with a stop command in the lawn mower operationmode. This enables the operator to double-tap the robotic lawn mower 100 in front tomake it stop (or as discussed above) to continue operation). Another example is where adouble-tap provides a stop command, and as the robotic lawn mower 100 has stopped,any collision event is associated with a continue operation command.

Further examples of collision events and associated commands are: Double front collision - INITIATE SPECIFIC NAVIGATION (such asfollow-me-mode) Double rear collision - RETURN TO CHARGING STATION or otherspecific location (such as dumping location) Rear collision when stopped - PROCEED Front collision when stopped - PREOCEED IN REVERSE Front collision when stopped - PREOCEED WITH DISENGAGED TOOL(FOR A TIME PERIOD).

The command is thus an operator command to be distinguished from theevasive navigation action that is norrnally triggered by a collision detector and asdiscussed in relation to the embodiments of figure 1B, such as reverse, tum and propelaway.

It should be noted that as most robotic lawn mowers travel at a relativelyconstant speed and the constant speed will in most cases result in a collision event of thesame amplitude, with variance caused by the direction of the collision. However, the direction of the collision may also be detected through the collision detector 175 and/or through the deduced reckoning Sensors, such as an accelerometer 180. As the inventorshave realized, the robotic lawn mower will therefore be able, in some embodiments, todifferentiate between a real collision event and a collision event generated by anoperator based on the amplitude of the collision event.

Figure 5 shows a flowchart of a general method according to the teachingsherein. A robotic working tool 100 such as a robotic lawn mower comprises a work tooland an attachment receiver 310 arranged to receive an attachment 320 as discussed inthe above. The robotic lawnmower is arranged to receive 510 information regarding theattachment 320 being received in the attachment receiver 310. In response thereto therobotic lawn mower 100 changes 520 its operation to operate in an attachment operatingmode, being different from the operating without the attachment. The robotic lawnmower 100 also deterrnines 530 an aspect of the attachment 320 and adapts 540 theoperation in the attachment operating mode to accommodate for the deterrnined aspect.The aspect is in one embodiment a weight or an indication of a weight of theattachment.

Figure 4 shows a flowchart of a general method according to the teachingsherein. A robotic lawn mower (100) comprises at least one collision detector (175), andreceives information from the at least one collision detector (175) indicating a collisionevent, i.e. the robotic lawn mower 100 registers 410 a collision event. The robotic lawnmower 100 interprets 420 the collision event as an operator command associated with the collision event and executes 430 the operator command.

Claims (28)

1. A robotic Working tool system (200) comprising a robotic Working tool(100) comprising a Work tool (160), an attachment receiver (310) arranged to receive anattachment (320) and a controller (110), the controller (110) being conf1gured to receive inforrnation regarding an attachment (320) being received, and inresponse thereto change the operation of the robotic Working tool (100) to operate in anattachment operating mode, and to determine an aspect of the attachment (320) andadapt the operation in the attachment operating mode to accommodate for the deterrnined aspect.

2. The robotic Working tool system (200) according to claim 1, Wherein the aspect is an indication of the Weight of the attachment (320).

3. The robotic Working tool system (200) according to claim 2, Wherein therobotic Working tool (100) comprises an outer shell (140-2) and an inner hull (140-1),Wherein the attachment receiver is mechanically connected to the outer shell (140-2),and Wherein the controller (110) is configured to determine the Weight of the attachment(320) based on a relative movement between the outer shell (140-2) and the inner hull (140-1).

4. The robotic Working tool system (200) according to any preceding claim,Wherein the robotic Working tool (100) further comprises at least one collision detector(175), and Wherein the controller (110) is further configured to adapt the operation inthe attachment operating mode to accommodate for the deterrnined aspect by adapting the operation of at least one of the at least one collision detector (175).

5. The robotic Working tool system (200) according to any preceding claim,Wherein the robotic Working tool (100) further comprises at least one lift detector (176), and Wherein the controller (110) is further configured to adapt the operation in the attachment Operating mode to accommodate for the deterrnined aspect by adapting the operation of at least one of the at least one lift detector (176).

6. The robotic Working tool system (200) according to any preceding claim,Wherein the controller (110) is further conf1gured adapt the operation of the robotic Working tool (100) to enable a follow-me-mode.

7. The robotic Working tool system (200) according to any preceding claim,Wherein the controller (110) is further conf1gured adapt the operation of the robotic Working tool (100) to enable a follow-boundary-mode.

8. The robotic Working tool system (200) according to any preceding claim,Wherein the controller (110) is further conf1gured adapt the operation of the robotic Working tool (100) to enable a Virtual-map-navigation mode.

9. The robotic Working tool system (200) according to any preceding claim,Wherein the controller (110) is further configured to adapt the operation toaccommodate for the deterrnined aspect by adapting the driving of the robotic Working tool (100).

10. The robotic Working tool system (200) according to any precedingclaim, Wherein the controller (110) is further configured to receive informationregarding a type of attachment and adapt the operation according to the type of attachment.

11. The robotic Working tool system (200) according to claim 10, Wherein the type of attachment is a load receiving attachment.

12. The robotic Working tool system (200) according to claim 10, Wherein the type of attachment is a second Work tool.

13. The robotic Working tool system (200) according to any of claims 10 to12, Wherein the controller (110) is further conf1gured to adapt the operation toaccommodate for the type of attachment (320) by adapting the driving of the roboticWorking tool (100).

14. The robotic Working tool system (200) according to any of claims 9 to13, Wherein the robotic Working tool (100) comprises at least one Wheel (l30a) having afirst diameter, and at least one second Wheel (l30b) having a second diameter Whereinthe second diameter is larger than the first diameter, and Wherein the controller (110) isfurther conf1gured to adapt the driving of the robotic Working tool (100) by causing therobotic Working tool (100) to travel With the at least one second Wheel (l30b) forwards.

15. The robotic Working tool system (200) according to any precedingclaim, Wherein the robotic Working tool (100) comprises at least one collision detector(175) When not being dependent on claim 4, and Wherein the controller (110) is furtherconfigured to receive information from the at least one collision detector (175) and toexecute an operator command associated With the information received from the at least one collision detector (175).

16. The robotic Working tool system (200) according to claim 15, Whereinthe controller (110) is further configured to execute the operator command associatedWith the information received from the at least one collision detector (175) Whenoperating in the attachment operating mode and to execute an evasive navigation actionassociated With the information received from the at least one collision detector (175) When operating in the Working tool operating mode.

17. The robotic Working tool system (200) according to any precedingclaim, Wherein the controller (110) is further conf1gured to receive information regarding the attachment (320) being removed, and inresponse thereto adapt the operation of the robotic Working tool (100) to operate in a Working tool operating mode.

18. The robotic Working tool system (200) according to any precedingclaim, Wherein the attachment receiver (310) is arranged to receive the attachment (320) in addition to the Work tool (160).

19. The robotic Working tool system (200) according to any precedingclaim, Wherein the robotic Working tool is a robotic laWnmoWer, and the Work tool (160) is a grass cutting device (160).

20. A method for use in a robotic Working tool system (200) comprising arobotic Working tool (100), comprising a Work tool (160) and an attachment receiver(310) arranged to receive an attachment (320) the method comprising: receiving information regarding an attachment (320) being received, and inresponse thereto changing the operation of the robotic Working tool (100) to operate inan attachment operating mode, and deterrnining an aspect of the attachment (320) andadapting the operation in the attachment operating mode to accommodate for the deterrnined aspect.

21. A robotic Working tool system (200) comprising a robotic Working tool(100) comprising a controller (110) and at least one collision detector (175), Wherein thecontroller (110) is configured to: receive information from the at least one collision detector (175) indicatinga collision event; interpret the collision event as an operator command associated With thecollision event; and to execute the operator command.

22. The robotic Working tool system (200) according to claim 21, Whereinthe robotic Work tool comprises an outer shell (140-2) and Wherein the collision event is generated by an operator engaging the outer shell (140-2).

23. The robotic Working tool system (200) according to claim 21 or 22,Wherein the collision event is indicative of a single collision, such as a forwards or rearwards collision.

24. The robotic Working tool system (200) according to claim 23, Whereinthe associated command is one taken from the group comprising to stop if in movement,to initiate movement if not in movement or to activate/deactivate a Work tool or attachment.

25. The robotic Working tool system (200) according to any of claims 21 to24, Wherein the collision event is indicative of a series of collisions, such as a forwards- forwards collision or rearwards-rearwards collision.

26. The robotic Working tool system (200) according to claim 25, Whereinthe associated command is one taken from the group comprising to change direction, to retum to a specific location, to initiate a specific navigation mode.

27. , The robotic Working tool system (200) according to any of claims 21 to 26, Wherein the robotic Working tool (100) is a robotic lawn moWer (100).

28. A method for use in a robotic Working tool system (200) comprising arobotic Working tool (100) comprising at least one collision detector (175), the methodcomprising: receiving information from the at least one collision detector (175)indicating a collision event; interpreting the collision event as an operator command associated With thecollision event; and to executing the operator command.