SE2150497A1

SE2150497A1 - Improved obstacle handling for a robotic work tool

Info

Publication number: SE2150497A1
Application number: SE2150497A
Authority: SE
Inventors: Dan Liljedahl; Daniel Wikestad; Douglas Fröling; Ivo Vryashkov; Marcus Johansson; Viktor Jansson
Original assignee: Husqvarna Ab
Priority date: 2021-04-22
Filing date: 2021-04-22
Publication date: 2022-10-23
Also published as: DE102022109611A1

Abstract

A method for use in a robotic work tool system (300) comprising a robotic working tool (200), and wherein the method comprises: detecting (510) an obstacle (S) along a first pattern line of the operating pattern in a first direction; selecting (520) a next pattern line; travelling (530) to the next pattern line; operating (540) along the next pattern line; returning (560) to the first pattern line; and operating on the first pattern line in a second direction, wherein the second direction is opposite the first direction.

Description

IMPROVED OBSTACLE HANDLING FOR A ROBOTIC WORK TOOL TECHNICAL FIELD This application relates to robotic work tools and in particular to a system and a method for providing an improved obstacle handling for a robotic work tool, such as a lawnmower.

BACKGROUND Automated or robotic power 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 enclosed by a boundary with the purpose of keeping the robotic lawnmower inside the work area. The work area may also be limited by objects such as walls or rocks. The boundary may be a physical boundary such as provided by a boundary wire emitting a magnetic field that can be sensed by the robotic working tool. Altematively or additionally to the boundary wire, many robotic Working tools are arranged to operate and navigate using a satellite navigations system, such as GNSS or GPS. The robotic working tool may also or altematively be arranged to operate or navigate utilizing a beacon-based navigation system, such as UWB or RTK. In either case, the robotic working tool is often arranged to perform more or less advanced operating pattems, such as for example mowing a lawn so that a specific pattem in the grass is produced, such as when mowing a football field.

One particular mowing pattem is to mow the lawn in straight parallel lines. This operation pattem is not only common to lawnmowers, but also to other robotic work tools, such as sweepers, vacuum cleaners, and floor cleaners to name a few.

However, often obstacles are present that interrupt the intended propulsion of the robotic work tool, thereby also interrupting the intended operation pattem.

Figure 1A shows a schematic view of an example of a typical work area 105, being a garden, in which a robotic work tool 10, such as a robotic lawnmower, is set to operate.

The garden contains a number of obstacles, exemplified herein by a number (2) of trees (T), a stone (S) 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). The garden is enclosed by a boundary wire 120 through which a control signal 125 is transmitted by a signal generator 115 housed in a charging station 110, the control signal 125 generating a magnetic field that can be sensed by the robotic work tool 10. The garden may also comprise or be in the line of sight of at least one signal navigation device 130. In this example the signal navigation device 130 is exemplified as a beacon, but it should be noted that it may also be any number of satellites. The use of satellite and/or beacon navigation enables for a boundary that is virtual, in addition to or as an alternative to the boundary wire 120. A virtual boundary 120" is indicated in figure 1 by the dotted line. From hereon there will be made no difference between the boundary being defined by the boundary wire 120 or as a virtual boundary 120" and the boundary of the work area 105 will hereafter simply be referred to as the boundary 120, unless otherwise specifically mentioned. In the example of figure 1, the robotic Working tool is set to operate according to a specific pattem P indicated by the dashed arrow in figure 1A.

The operation pattem is made up of a number of parallel lines that are traversed in tum. As can be seen, the stone S is in the way of the robotic lawnmower as it will attempt to execute the operating pattem. This will force the robotic lawnmower to deviate from the intended operating pattem in order to avoid the obstacle, which will lead to a pattem (possibly in a pattem in the grass) that does not correspond to the intended operating pattem.

Figure 1B shows an example of how the resulting operating pattem will look like if the robotic lawnmower is configured to go around the obstacle. However, this requires exact and precise knowledge of the shape of the object, which is not always available and requires a highly complicated robotic lawnmower, which are very costly.

Figure 1C shows another example where the robotic lawnmower tums away from the obstacle and continues the operating pattem, but from a new position.

As can be seen, the resulting operating pattem is not the same as the intended in either case, and in the case of figure 1C, the resulting operating pattem leaves unattended areas referenced UA.

Thus, there is a need for an improved manner of enabling a robotic working tool to continue an operation pattem even after an obstacle has been encountered.

SIHVIMARY It is therefore an object of the teachings of this application to overcome or at least reduce those problems by providing a robotic Work tool systern comprising a robotic Working tool configured to operate in an operating pattern (P), the robotic Working tool comprising a controller configured to: detect an obstacle (S) along a first pattern line of the operating pattern in a first direction; select a next pattern line; travel to the next pattern line; operate along the next pattern line; return to the first pattern line; and operate on the first pattern line in a second direction, Wherein the second direction is opposite the first direction.

In some embodiments the controller is ﬁirther configured to travel to the next pattern line by retuming to a starting point of the first pattern line and travelling to an end point of the next closest adj acent pattern line, the end point thereby being the starting point for operating on the next pattern line.

In some embodiments the controller is ﬁirther configured to retum to the first pattem line by travelling to the end of the first pattem line.

In some embodiments the controller is ﬁirther configured to travel to the next pattem line by: tuming away from the first pattem line; travelling to an interrnediate pattem line, the interrnediate pattem line being the closest adj acent pattem line; operating along the interrnediate pattem line in the second direction; and then travelling to the next adj acent pattem line.

In some embodiments the controller is further configured to retum to the first pattem line by travelling to the end of the interrnediate pattem line; operating along the interrnediate pattem line to complete the interrnediate pattem line and then travelling to the end of the first pattem line.

In some embodiments the operating pattem comprises a plurality of adj acent pattem lines.

In some embodiments the plurality of adj acent pattem lines are equidistant to one another.

In some embodiments the controller is ﬁirther configured to travel along pattem lines and/or a shortest straight distance between pattem lines.

In some embodiments the robotic work tool comprises a working tool and wherein the controller is further configured to deactivate the working tool when the robotic work tool travels between pattern lines.

In some embodiments the controller is further configured to deactivate the working tool when the robotic work tool travels on already operated on pattern lines.

In some embodiments the robotic work tool is configured for operating in a work area comprising an uneven surface, where objects are of a similar appearance to the surface and/or overhanging obstacles.

In some embodiments the robotic work tool is a robotic lawnmower.

In some embodiments the robotic work tool is a vacuum cleaner.

In some embodiments the robotic work tool is a golf ball collector.

In some embodiments the robotic work tool is a polishing robot.

In some embodiments the robotic work tool is a cleaner robot.

It is also an object of the teachings of this application to overcome the problems by providing a method for use in a robotic work tool system comprising a robotic working tool, and wherein the method comprises: detecting an obstacle along a first pattem line of the operating pattem in a first direction; selecting a next pattem line; travelling to the next pattem line; operating along the next pattem line; retuming to the first pattem line; and operating on the first pattem line in a second direction, wherein the second direction is opposite the first direction.

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 1A shows an example of a robotic work tool system being a robotic lawnmower system; Figure 1B shows an example of a resulting operating pattem in a robotic work tool system being a robotic lawnmower system as in figure 1A; Figure 1C shows an example of a resulting operating pattem in a robotic work tool system being a robotic lawnmower system as in figure 1A Figure 2A shows an example of a robotic work tool according to some embodiments of the teachings herein; Figure 2B shows a schematic View of the components of an example of a robotic work tool being a robotic lawnmower according to some example embodiments of the teachings herein; Figure 3 shows a schematic View of a robotic work tool system according to some example embodiments of the teachings herein; Figure 4A shows an example of a manner in which a robotic work tool is conf1gured to handle an obstacle encountered in an operating pattem according to some embodiments of the teachings herein; Figure 4B shows another example of a manner in which a robotic work tool is conf1gured to handle an obstacle encountered in an operating pattem according to some embodiments of the teachings herein; and Figure 5 shows a corresponding flowchart for a method according to some example embodiments of the teachings herein.

DETAILED DESCRIPTION The disclosed embodiments will now be described more ﬁally 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 farrning equipment, or other robotic work tools where a work tool is to operate in a pattern of adjacent lines. One such example is a polishing robot arranged to polish a concrete surface. Another such example is a cleaning robot arranged to clean a floor surface.

Figure 2A shows a perspective view of a robotic work tool 200, here exemplif1ed by a robotic lawnmower 200, having a body 240 and a plurality of wheels 230 (only one side is shown). The robotic work tool 200 may be a multi-chassis type or a mono-chassis type (as in figure 2A). A multi-chassis type comprises more than one main body parts that are movable with respect to one another. A mono-chassis type comprises only one main body part.

It should also be noted that the robotic work tool is a self-propelled robotic work tool, capable of autonomous navigation within a work area, where the robotic work tool propels itself across or around the work area in an operating pattem.

Figure 2B shows a schematic overview of the robotic work tool 200, also exemplif1ed here by a robotic lawnmower 200. In this example embodiment the robotic lawnmower 200 is of a mono-chassis type, having a main body part 240. The main body part 240 substantially houses all components of the robotic lawnmower 200. The robotic lawnmower 200 has a plurality of wheels 230. In the exemplary embodiment of figure 2B the robotic lawnmower 200 has four wheels 230, two front wheels and two rear wheels. At least some of the wheels 230 are drivably connected to at least one electric motor 250. It should be noted that even if the description herein is focused on electric motors, combustion engines may altematively be used, possibly in combination with an electric motor. In the example of figure 2B, each of the wheels 230 is connected to a common or to a respective electric motor 255 for driving the wheels 230 to navigate the robotic lawnmower 200 in different manners. The wheels, the motor 255 and possibly the battery 250 are thus examples of components making up a propulsion device. By controlling the motors 250, the propulsion device may be controlled to propel the robotic lawnmower 200 in a desired manner, and the propulsion device will therefore be seen as synonymous with the motor(s) 250.

The robotic lawnmower 200 also comprises a controller 210 and a computer readable storage medium or memory 220. The controller 210 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 220 to be executed by such a processor. The controller 210 is configured to read instructions from the memory 220 and execute these instructions to control the operation of the robotic lawnmower 200 including, but not being limited to, the propulsion and navigation of the robotic lawnmower.

The controller 210 in combination with the electric motor 255 and the wheels 230 forms the base of a navigation system (possibly comprising further components) for the robotic lawnmower, enabling it to be self-propelled as discussed under figure 2A, The controller 210 may be implemented using any suitable, available processor or Programmable Logic Circuit (PLC). The memory 220 may be implemented using any commonly known technology for computer-readable memories such as ROM, FLASH, DDR, or some other memory technology.

The robotic lawnmower 200 is further arranged with a wireless communication interface 215 for communicating with other devices, such as a server, a personal computer, a smartphone, the charging station, and/or other robotic work tools. Examples of such wireless communication devices are Bluetooth®, WiFi® (IEEE802.l lb), Global System Mobile (GSM) and LTE (Long Term Evolution), to name a few. The robotic lawnmower 100 is specif1cally arranged to communicate with a user equipment 300 as discussed in relation to figure 3 below for providing information regarding status, location, and progress of operation to the user equipment 300 as well as receiving commands or settings from the user equipment 300.

The robotic lawnmower 200 also comprises a grass cutting device 260, such as a rotating blade 260 driven by a cutter motor 265. The grass cutting device being an example of a work tool 260 for a robotic work tool 200. It should be noted that a robotic work tool may comprise one or more work tools, of a same type or of different types. As a skilled person would understand the cutter motor 265 is accompanied or supplemented by various other components, such as a drive shaft to enable the driving of the grass cutting device, taken to be understood as included in the cutter motor 265.

The cutter motor 265 Will therefore be seen as representing a cutting assembly 265 or in the case of another Work tool, a Work tool assembly 265.

The robotic laWnmoWer 200 may further comprises at least one navigation sensor, such as an optical navigation sensor, an ultrasound sensor, a beacon navigation sensor and/or a satellite navigation sensor 285. The optical navigation sensor may be a camera-based sensor and/or a laser-based sensor. The beacon navigation sensor 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. 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 Positioning System) device or other Global Navigation Satellite System (GNSS) device. In embodiments, Where the robotic laWnmoWer 200 is arranged With a navigation sensor, the magnetic sensors 270 as Will be discussed below are optional. In embodiments relying (at least partially) on a navigation sensor, the Work area may be specified as a virtual Work area in a map application stored in the memory 220 of the robotic laWnmoWer 200. The virtual Work area may be defined by a virtual boundary.

In the examples that Will be discussed herein the navigation sensor is a satellite navigation sensor, such as GPS, GNSS or a supplemental satellite navigation sensor such as RTK.

The robotic laWnmoWer 200 may also or altematively comprise deduced reckoning sensors 280. The deduced reckoning sensors may be odometers, accelerometer or other deduced reckoning sensors. In some embodiments, the deduced reckoning sensors are comprised in the propulsion device, Wherein a deduced reckoning navigation may be provided by knowing the current supplied to a motor and the time the current is supplied, Which Will give an indication of the speed and thereby distance for the corresponding Wheel.

For enabling the robotic laWnmoWer 200 to navigate With reference to a boundary Wire emitting a magnetic field caused by a control signal transmitted through the boundary Wire, the robotic laWnmoWer 200 is, in some embodiments, further configured to have at least one magnetic field sensor 270 arranged to detect the magnetic field and for detecting the boundary wire and/or for receiving (and possibly also sending) inforrnation to/ from a signal generator (will be discussed with reference to figure 1). In some embodiments, the sensors 270 may be connected to the controller 210, possibly via filters and an amplifier, and the controller 210 may be configured to process and evaluate any signals received from the sensors 270. The sensor signals are caused by the magnetic field being generated by the control signal being transmitted through the boundary wire. This enables the controller 210 to determine whether the robotic lawnmower 200 is close to or crossing the boundary wire, or inside or outside an area enclosed by the boundary wire.

As mentioned above, in some embodiments, the robotic lawnmower 200 may be arranged to operate according to a map of the work area 205 (and possibly the surroundings of the work area 205) stored in the memory 220 of the robotic lawnmower 200. The map may be generated or supplemented as the robotic lawnmower 200 operates or otherwise moves around in the work area 205.

The robotic Working tool 200 may also comprise additional sensors 290 for enabling operation of the robotic working tool 200, such as visual sensors (for example a camera), or ranging sensors.

There are thus many variations in how the robotic work tool 200 may be configured to navigate along the operating pattem using the various sensors that are to the disposal of the designer of the robotic lawnmower 200.

Figure 3 shows a robotic work tool system 300 in some embodiments. The schematic view is not to scale. The robotic work tool system 300 of figure 3, corresponds in many aspects to the robotic work tool system 100 of figure 1, except that the robotic work tool system 300 of figure 3 comprises a robotic work tool 200 according to the teachings herein. It should be noted that the work area shown in figure 3 is simplified for illustrative purposes but may contain some or all of the features of the work area of figure 1, and even other and/or further features as will be hinted at below.

As with figures 2A and 2B, the robotic work tool is exemplified by a robotic lawnmower, whereby the robotic work tool system may be a robotic lawnmower system or a system comprising a combinations of robotic work tools, one being a robotic lawnmower, but the teachings herein may also be applied to other robotic work tools adapted to operate within a work area.

The robotic work tool system 300 comprises a charging station 310 which in some embodiments is arranged with a signal generator (not shown) for providing a control signal through a boundary wire 320. As an electrical signal is transmitted through a wire, such as the control signal being transmitted through the boundary wire 320, a magnetic field is generated that can be sensed by the sensors 270. As mentioned above, the actual boundary wire is optional and the boundary 320 may be virtual, stored in a map application. The robotic Working tool system 300 may comprise or be arranged to utilize at least one signal navigation device 330. In the example of figure 3 two options are shown, a first being at least one satellite 330A (only one shown, but it should be clear that a minimum of three are needed for an accurate three 2 dimensional location). The second option being at least one beacon, such as an RTK beacon 330B (only one shown).

The work area 305 is in this application exemplified as a garden, but can also be other work areas as would be understood. As hinted at above, the garden may contain a number of obstacles, for example a number of trees, stones, slopes and houses or other structures.

In some embodiments the robotic work tool is arranged or configured to traverse and operate in a work area that is not essentially ﬂat, but contains terrain that is of varying altitude, such as undulating, comprising hills or slopes or such. The ground of such terrain is not ﬂat and it is not straightforward how to determine an angle between a sensor mounted on the robotic work tool and the ground. The robotic work tool is also or altematively arranged or conf1gured to traverse and operate in a work area that contains obstacles that are not easily discemed from the ground. Examples of such are grass or moss covered rocks, roots or other obstacles that are close to ground and of a similar colour or texture as the ground. The robotic work tool is also or altematively arranged or configured to traverse and operate in a work area that contains obstacles that are overhanging, i.e. obstacles that may not be detectable from the ground up, such as low hanging branches of trees or bushes. Such a garden is thus not simply a ﬂat lawn to be mowed or similar, but a work area of unpredictable structure and characteristics. The ll work area 305 exemplif1ed with referenced to figure 3, may thus be such a non-uniforrn work area as disclosed in this paragraph that the robotic work tool is arranged to traverse and/or operate in.

In the below several embodiments of how the robotic work tool may be adapted will be disclosed. It should be noted that all embodiments may be combined in any combination providing a combined adaptation of the robotic work tool.

An intended operating pattem P is illustrated by dashed lines in figure 3. As can be seen the operating pattem comprises a plurality of parallel pattem lines. In some embodiments the pattem lines are equidistant. In some embodiments the pattem lines are of equal length. It should be noted that even though the pattem is illustrated in figure 3 to have bridges or paths (the vertical line segments) between the parallel pattem lines, such bridges may not be part of the operating pattem and the robotic lawnmower 200 may simply choose them as a convenient way to travel between two parallel pattem lines. It should be noted that two pattem lines may not be strictly parallel even though referred to as parallel, as in real life it is difficult to achieve exactly straight lines and therefore also difficult to achieve strictly parallel lines. Two parallel lines may thus also be referred to as two adj acent lines.

As can be seen in the example of f1gure 3, there is an obstacle S in the path of the intended operating pattem P. In this example the obstacle S is a stone, however, there are many other types of obstacles including hindrances that may be encountered in a work area as a skilled person would understand.

The inventors have realized an elegant manner in which a maximum coverage of the intended operating pattem can be achieved at a minimum if effort and time leaving as small as possible unattended areas.

Figure 4A shows an example of how the robotic work tool 200 is configured, in some embodiments, to handle an encountered obstacle S.

Figure 4B shows another, but similar, example of how the robotic work tool 200 is conf1gured, in some embodiments, to handle an encountered obstacle S.

Figure 5 shows a ﬂowchart for a general method according to herein. The method is for use in a robotic work tool as in figures 2A and 2B. The improved manner for handling error codes as discussed herein will be discussed with simultaneous 12 reference to figures 4A and 4B and figure 5. In both figure 4A and 4B, the operating pattern will be shown in full lines where the pattern has been operated in.

As the robotic working tool 200 encounters or detects 510 an obstacle in the path of the intended operating pattern. The object S may be detected using a variety of techniques and/or sensors, such as, but not limited to collision sensors, lift sensors, ultrasonic distance sensors, detecting a change in the cutting motor (blade blocked), Radar, and/or (camera) vision systems. It could be noted that the robotic lawnmower may detect the obstacle at different distances when using different techniques/sensors. The object may also be detected using a combination of sensors or by a combination of inputs from a same sensor, where for example an ultrasonic sensor is used, the object may be detected at a long range, whereby the robotic lawnmower may continue to approach the object, possibly at a reduced speed. Later the object detection may be supplemented by a different or the same sensor. In this example, the robotic lawnmower 200 detects the obstacle as it travels towards the obstacle (arrow 1). The robotic lawnmower 200 then selects 520 an adj acent pattem line of the operating pattem to continue operating on, travels 530 to that adj acent pattem line of the operating pattem (arrows 2 and 3 in figure 4A and arrow 2 in figure 4B) and continues operating 540 on that adj acent pattem line (arrow 4 in figure 4A and arrow 3 in figure 4B). As the robotic lawnmower 200 travels to the adj acent line, the robotic lawnmower 200 may halt or deactivate the working tool, i.e. the cutter 160 in the case of a robotic lawnmower 200. This to avoid waste of battery power, but also to ensure an even resulting pattem. As an end of the adj acent pattem line is reached 550, the robotic lawnmower 200 travels 560 to the end of the original or skipped pattem line (the one that the obstacle was encountered on) (arrow 5 in figure 4A and arrows 4, 5, 6, 7, 8, 9 in figure 4B) and continues operating 570 on the skipped pattem line, but in an opposite direction (arrow 6 in figure 4A and arrow 10 in figure 4B).

This enables the robotic lawnmower 200 to try to complete the operating pattem despite the presence of the obstacle S, with a minimum of effort and with an even resulting pattem as the robotic lawnmower 200 only travels via intended paths of the operating pattem (at least with the working tool active). 13 This also enables the robotic lawnmower 200 to attempt overcoming an obstacle. As some obstacles or hindrances may only be an obstacle in one direction (for example a steep slope, a branch that only bends (easily) in one direction or a garden gate that only opens in one direction), this two-folded attempt at overcoming the obstacle in two (opposite) directions will enable the robotic lawnmower 200 to overcome such obstacles even though the initial encounter was in a direction in which the obstacle could not be overcome.

The robotic lawnmower 200 then continues operation 580 in the operating pattem (arrow 9 in figure 4A and arrow 13 in figure 4B) to complete the operating pattem. To do this, the robotic lawnmower 200 is in some embodiments, configured to backtrack in already operated paths (possibly with cutter deactivated) to a next starting point in the operating pattem, i.e the start of an operating line that has yet not been attended to (arrow 7 in figure 4A and arrows 11 and 12 in figure 4B). In some embodiments, the robotic lawnmower 200 is configured to travel the most direct path (with cutter deactivated) to the next starting point.

Retuming to the travelling 530 to the adj acent pattem line. In some embodiments, as illustrated in figure 4A, the robotic lawnmower 200 is configured to retum to the starting point of the current pattem line, i.e. the pattem line to be skipped. The retuming to the starting point may be done by reversing the same way, or by tuming and following the same path that was travelled before (arrow 2). As the starting point of the skipped line is reached, the robotic lawnmower 200 is configured to make a 90 degree tum and to travel to the starting point closest (i.e. the shortest distance) for the adj acent pattem line (arrow 3). The robotic lawnmower 200 then operates 550 along the adj acent pattem line (arrow 4). The end of the next (selected) pattem line is eventually reached.

In some embodiments, as illustrated in figure 4B, the robotic lawnmower 200 is configured to tum 90 degrees and cross over to the next (closest, but not serviced) adj acent pattem line (arrow 2). This crossing is in some embodiments performed with the cutter deactivated. The robotic lawnmower 200 is then configured to tum 90 degrees again and operate along this adj acent pattem line, but in an opposite direction from before (in a direction towards the starting point of the skipped pattem line). In some 14 embodiments this is achieved by the two 90 degree tums being made in the same (angular) direction (arrow 3). It could be noted that the whole length of this pattern line will most likely not be serviced in this pass, wherefore his adj acent line may be referred to as an interrnediate adj acent pattem line. As the robotic lawnmower 200 reaches the starting point of this interrnediate adj acent pattem line, The robotic lawnmower tums (90 degrees) and travels to the next adj acent pattem line (arrow 4) and operates along this next adj acent pattem line (arrow 5). This pattem line will be the selected next pattem line, as the whole length of this adjacent pattem line will be serviced in one pass (unless another obstacle is encountered). The end of the next (selected) pattem line is eventually reached.

As noted above, as the end of the next (selected) pattem line is reached, the robotic lawnmower 200 travels 560 to the end of the original or skipped pattem line.

In some embodiments, as illustrated in figure 4A, the robotic lawnmower 200 is configured to (simply) tum (90 degrees) towards the original or skipped pattem line and travel to its end point (arrow 5).

In some embodiments, as illustrated in figure 4A, the robotic lawnmower 200 is conf1gured to tum (90 degrees) and travel to the starting point of the interrnediate adj acent pattem line (arrow 6). The robotic lawnmower 200 then operates along the not- yet-serviced part of the interrnediate pattem line (arrow 7). As the robotic lawnmower cut across from the first apttem line before reaching the end, the interrnediate pattem line is not fully serviced (or operated on). The remainder of the interrnediate pattem line is thus completed by the robotic lawnmower 200. The robotic lawnmower 200 then retums to the starting point of the interrnediate pattem line (arrow 8). The robotic lawnmower 200 then continues to the starting point (or rather end point) of the skipped pattem line (arrow 9). It should be noted that the completion of the interrnediate pattem line may be done as part of travelling to the end point of the skipped pattem line, or as part of travelling to a next starting point for continued 570 operation. In the example of figure 4B, the arrows 7 and 8 may thus be done in between arrows 6 and 9, or as part of arrow l2.

As can be seen, figure 4A shows a first manner of handling an obstacle and to make sure that the operating pattem is completed and figure 4B shows a second manner of handling an obstacle and to make sure that the operating pattern is completed. In some embodiments, the robotic laWnmoWer 200 is configured to select Which of the first and the second manner to execute as part of the selection of the next adj acent pattern line 520.

The selection of Which of the first and the second manner to execute is, in some embodiments, made based on area information, such as Which route is the most easy to travel. Such information may be part of a map application. The selection of Which of the first and the second manner to execute is, in some embodiments, made based on an intended direction of the pattem, such as When mowing football fields.

Both manners provide advantages in that the operating pattem is completed Without Wasting energy or time. Also, the robotic laWnmoWer 200 only travels in paths that are safe, i.e. along the pattem lines. The robotic laWnmoWer 200 further is almost guaranteed to detect objects safely as the robotic laWnmoWer 200 only travels in straight directions and Will therefore encounter al obstacles head on (Which is the intended manner of detecting objects and thus the safest).

It should be noted that an end point of a pattem line, may be either ends of the pattem line, i.e. both the starting point and the end of the pattem line are end points. Unless the operating pattem is directional, the starting point is the end point Where operation along that pattem line (happens to) start, and the ending point or end of the pattem line is Where the operation (happens to) end.

Claims

1. 1. A robotic Work tool system (300) comprising a robotic Working tool (200) conf1gured to operate in an Operating pattern (P), the robotic Working tool (200) comprising a controller configured to: detect (510) an obstacle (S) along a first pattern line of the operating pattern in a first direction; select (520) a next pattern line; travel (530) to the next pattern line; operate (540) along the next pattern line; return (560) to the first pattern line; and operate on the first pattern line in a second direction, Wherein the second direction is opposite the first direction.

2. The robotic Work tool system (300) according to claim 1, Wherein the controller is further conf1gured to travel (530) to the next pattern line by retuming to a starting point of the first pattern line and travelling to an end point of the next closest adjacent pattern line, the end point thereby being the starting point for operating on the next pattern line.

3. The robotic Work tool system (3 00) according to claim 2, Wherein the controller is further conf1gured to return (5 60) to the first pattern line by travelling to the end of the first pattern line.

4. The robotic Work tool system (3 00) according to claim 1, Wherein the controller is further conf1gured to travel (530) to the next pattem line by: tuming away from the first pattem line; travelling to an interrnediate pattem line, the interrnediate pattem line being the closest adj acent pattem line; operating along the interrnediate pattem line in the second direction; and then travelling to the next adj acent pattem line.

5. The robotic Work tool system (3 00) according to claim 4, Wherein the controller is further conf1gured to return (560) to the first pattern line by travelling to the end of the interrnediate pattern line; operating along the interrnediate pattern line to complete the interrnediate pattern line and then travelling to the end of the first pattern line.

6. The robotic Work tool system (3 00) according to any preceding claim, Wherein the operating pattern comprises a plurality of adj acent pattern lines.

7. The robotic Work tool system (300) according to claim 6, Wherein the plurality of adjacent pattern lines are equidistant to one another.

8. The robotic Work tool system (3 00) according to any preceding claim, Wherein the controller is further conf1gured to travel along pattern lines and/or a shortest straight distance between pattern lines.

9. The robotic Work tool system (3 00) according to any preceding claim, Wherein the robotic Work tool (200) comprises a Working tool (160) and Wherein the controller is further conf1gured to deactivate the Working tool (l60) When the robotic Work tool (200) travels between pattem lines.

10. l0. The robotic Work tool system (3 00) according to claim 9, Wherein the controller is further conf1gured to deactivate the Working tool (l60) When the robotic Work tool (200) travels on already operated on pattem lines.

11. ll. The robotic Work tool system (3 00) according to any previous claim, Wherein the robotic Work tool is conf1gured for operating in a Work area comprising an uneven surface, Where objects are of a similar appearance to the surface and/or overhanging obstacles.12. The robotic Work tool system (300) according to any previous claim,

12. Wherein the robotic Work tool is a robotic laWnmoWer.

13. A method for use in a robotic Work tool system (300) comprising a robotic Working tool (200), and Wherein the method comprises: detecting (510) an obstacle (S) along a ﬁrst pattem line of the operating pattem in a ﬁrst direction; selecting (520) a next pattem line; traVelling (530) to the next pattem line; operating (540) along the next pattem line; retuming (560) to the ﬁrst pattem line; and operating on the ﬁrst pattem line in a second direction, Wherein the second direction is opposite the ﬁrst direction.