IMPROVED NAVIGATION FOR A ROBOTIC WORK TOOL SYSTEM

TECHNICAL FIELD

This application relates to a robotic work tool and in particular to a system and a method for providing an improved navigation for robotic work tools, such as lawnmowers, in such a system.

BACKGROUND

Automated or robotic work tools such as robotic lawnmowers are becoming increasingly more popular and so is the use of the same robotic working tool(s) in more than one work area. The more than one work areas can be subareas or they can be separate work areas, either adjacent one another or located remotely from one another. As a work area does not need to be serviced continuously, the robotic working tool(s) can alternate between servicing a first work area and a second work area. As a robotic working tool(s) 200 is to move from the first work area to the second work area designated transport areas or corridors may be utilized, where the designated transport areas are deemed safe for the robotic working tool(s) to travel through, so that the robotic working tool(s) will not get stuck, interfere with other robotic working tools or other devices or operators.

The patent application published as W02021066702A1 discloses such a robotic work tool system for avoiding trails from a robotic work tool in a transit zone in which the robotic work tool is allowed to travel from a start point to a goal point along a travel path. The system comprises at least one memory configured to store information about the transit zone, at least one robotic work tool configured to travel along the travel path and at least one controller for controlling operation of the robotic work tool. The controller is configured to receive, from the memory, information about the transit zone and generate, based on the transit zone, the travel path for the robotic work tool from the start point to the goal point. The generated travel path is configured to differ from previously generated travel paths.

The patent application published as US2016174459A1 discloses such a system, disclosing a method of mowing multiple areas includes training the robotic mower to move across a space separating at least two areas, and initiating a mowing operation. Training the robotic mower to move across the space separating the areas includes moving the robotic mower to a traversal launch point of a first of the areas, storing data indicative of location of the traversal launch point, moving the robotic mower to a traversal landing point of a second of the areas, and storing data indicative of location of the traversal landing point. The mowing operation causes the robotic mower to autonomously and in sequence mow the first of the areas, move to the traversal launch point, move from the traversal launch point across the space to the traversal landing point, and then mow the second of the areas.

Figure 1A shows a schematic view of an example of atypical work area 105, being a garden, in which a robotic work tool 10, such as a robotic lawnmower, is set to operate. Another example of a typical work area is an airport field, which also comprises many of the same elements as the garden, however at a larger scale (assumingly).

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 may be 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. In this example the boundary wire 120 is laid so that so-called islands are formed around the trees and the house. 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 here on 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 order to control the robotic working tool more efficiently, the robotic working tool 10 may be connected to a user equipment 30, such as a smartphone, executing a robotic working tool control application. The robotic working tool control application receives information from the robotic working tool in order to provide updated status reports to an operator. The operator is also enabled to provide commands to the robotic working tool 10 through the robotic working tool controlling application. The commands may be for controlling the propulsion of the robotic working tool, to perform a specific operation or regarding scheduling of the robotic working tool’s operation.

Alternatively or additionally the robotic working tool 10 may be connected to a cloud service or server 40 for receiving commands and or other data enabling a more efficient operation of the robotic working tool(s) 10.

In the example of figure 1, the work area 105 has two sub work areas 105 A and 105B, which hereafter will be referred to as a first work area 105 A and a second work area 105B respectively. A designated transport area TA is shown between the two work areas, enabling a robotic working tool(s) 10 to travel along a travel path TP from a start region SR in the first work area 105 A to an goal region ER in the second work area 105B.

In the example of figure 1 A, there is also a second robotic working tool(s) 10B operating in the second work area 105B. Figure IB shows a schematic view of one problem situation that could occur for a robotic working tool(s) system as shown in figure 1 A. Figure IB only shows a subset of what is shown in figure 1 A to provide for an unencumbered illustration, but it should be noted that all or some of what is shown in figure 1 A may also be present in figure IB.

As is shown in figure IB there might be problems when two or more robotic working tools are travelling through the transport area at the same time which may lead to collisions, congestions or other situations that may block or hinder an robotic working tool(s) 10. In figure IB it is shown that the transport path TPA of the first robotic working tool(s) 10A crosses the transport path TPB of the second robotic working tool(s) 10B, which may lead to collisions if the two robotic working tools are to travel through the transport area at roughly the same time. In the situation of figure IB, the two robotic working tools 10 are travelling in opposite directions, but it should be clear that the same or similar problems may occur regardless of direction travelled. The problems may occur regardless of the size of the transport area, especially as some prior art systems change the travel path to avoid tracks being formed, which results in that robotic working tools may be anywhere in the transport area TA.

Thus, there is a need for an improved manner of enabling a robotic working tool to navigate a transport area without causing collisions, congestions or other impediments to itself and/or other robotic working tools.

SUMMARY

It is therefore an object of the teachings of this application to overcome or at least reduce those problems by providing by providing a robotic work tool system for navigating two or more robotic work tools in a transport area, the transport area being an area in which the two or more robotic work tools are allowed to travel between a first region and a second region, wherein the robotic work tool system comprises: at least one memory configured to store information about the transport area; two or more robotic work tools configured to travel within the transport area; and at least one controller for controlling operation of the at least one robotic work tool, the at least one controller being configured to: receive, from the at least one memory, information about the transport area; and navigate the two or more robotic work tools between the first end region and the second end region, wherein the robotic work tool system is characterized in that the transport area is associated by constraints and the at least one controller being further configured to navigate the two or more robotic work tools based on said constraints in order to avoid possible collisions between and/or blockings of at least one of the one or more robotic work tools.

In some embodiments the constraints relate to at least two pathways within the transport area that the one or more robotic working tools are allowed to navigate within when navigation through the transport area between the first end region and the second end region.

In some embodiments a first of the at least two pathways allow for travel in a first direction and wherein a second of the at least two pathways allow for travel in a second direction and the first direction is opposite the second direction.

In some embodiments the constraints relate to an allowed speed. In some embodiments the constraints relate to a first allowed speed for a first of the at least two pathways and a second allowed speed for a second of the at least two pathways.

In some embodiments the first allowed speed relate to a minimum speed the second allowed speed relate to a maximum speed, and wherein the first pathway is arranged adjacent the second pathway, wherein the minimum speed is higher than the maximum speed.

In some embodiments the constraints relate to a maximum number of robotic working tools in one of the at least two pathways.

In some embodiments the constraints relate to a minimum distance between two robotic working tools in one of the at least two pathways.

In some embodiments the constraints relate to a maximum entry rate for robotic working tools into one of the at least two pathways.

In some embodiments the first end region is in a first work area and the second end region is in a second work area.

In some embodiments the constraints relate to an operating mode.

In some embodiments the constraints relate to a current weather.

In some embodiments the constraints relate to the transport area.

In some embodiments the controller is configured to detect that an event occurs in the transport area and to adapt the constraints based on the detected event.

In some embodiments the event is that an object is detected.

In some embodiments the object detected is another robotic working tool, whereby the controller is configured to adapt the constraints so as to avoid a collision with the another robotic working tool.

In some embodiments the controller is configured to halt and generate movement data for the detected object and adapt the constraints based on the movement data.

In some embodiments the controller is configured to halt and generate image data for the detected object, classify the object based on the image data and adapt the constraints based on the classification.

In some embodiments the controller is a controller of the robotic working tool. In some embodiments the controller is a controller of a server connected to the robotic working tool system.

In some embodiments the controller is configured to determine that the connection to the server is no longer active and in response thereto control the operation of the robotic working tool.

In some embodiments the controller is a controller of a user device connected to the robotic working tool system.

In some embodiments the controller is configured to determine that the connection to the user device is no longer active and in response thereto control the operation of the robotic working tool.

In some embodiments the controller is further configured to determine a condition of the transport area and to determine the constraints based on the condition.

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

It is also an object of the teachings of this application to overcome the problems by providing a method for use in a robotic work tool system comprising two or more robotic working tools, wherein the method comprises determining a navigation for the two or more robotic working tools through a transport area so that collision or other impediment do not occur.

It is also an object of the teachings of this application to overcome the problems by providing a robotic work tool comprising a controller, wherein the robotic work tool is configured to operate as the robotic work tool of any of the systems above.

In some embodiments the robotic work tool comprises at least one memory configured to store information about the transport area TA; two or more robotic work tools configured to travel within the transport area TA; wherein the controller is configured to: receive, from the at least one memory, information about the transport area TA; and navigate the robotic work tool between the first end region GR, SR and the second end region based on said constraints in order to avoid possible collisions between and/or blockings of at least one of the two or more robotic work tools.

In some embodiments the controller is further configured to determine that the robotic work tool is to enter the transport area, and n response thereto transmit an indicator of the robotic work tool to a server; receive said constraints from said server; compare the constraints with parameters for the robotic work tool 200, and, if the constraints are within the parameters, navigate the transport area.

In some embodiments the controller is further configured to transmit an acceptance to the server if the constraints are within the parameters.

In some embodiments the constraints are based on the properties of the robotic work tool.

It is also an object of the teachings of this application to overcome the problems by providing a method for use in robotic work tool for implementing a robotic work tool for use in the system according to herein.

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 1 A shows an example of a robotic work tool system being a robotic lawnmower system;

Figure IB shows a subset of the example of figure 1 A;

Figure 2A shows an example of a robotic lawnmower 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 an example of a user equipment according to some embodiments of the teachings herein;

Figure 4A shows a schematic view of a robotic work tool system according to some example embodiments of the teachings herein;

Figure 4B shows a schematic view of a robotic work tool system according to some example embodiments of the teachings herein;

Figure 4C shows a schematic view of a robotic work tool system according to some example embodiments of the teachings herein;

Figure 4D shows a schematic view of a robotic work tool system according to some example 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 fully hereinafter with reference to the accompanying drawings, in which certain embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Like reference numbers refer to like elements throughout.

It should be noted that even though the description given herein will be focused on robotic lawnmowers, the teachings herein may also be applied to, robotic ball collectors, robotic mine sweepers, robotic farming equipment, or other robotic work tools where a work tool is to be safeguarded against from accidentally extending beyond or too close to the edge of the robotic work tool.

Figure 2A shows a perspective view of a robotic work tool 200, here exemplified 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 be noted that robotic lawnmower may be of different sizes, where the size ranges from merely a few decimetres for small garden robots, to almost 2 meters for large robots arranged to service for example airfields.

It should be noted that even though the description herein is focussed on the example of a robotic lawnmower, the teachings may equally be applied to other types of robotic work tools, such as robotic watering tools, robotic golfball collectors, robotic mulchers to mention a few examples.

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 a pattern (random or predetermined).

Figure 2B shows a schematic overview of the robotic work tool 200, also exemplified 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 alternatively 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.

It should be noted that wheels 230 driven by electric motors is only one example of a propulsion system and other variants are possible such as caterpillar tracks.

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® (IEEE802.1 lb), Global System Mobile (GSM) and LTE (Long Term Evolution), to name a few. The robotic lawnmower 100 may be 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. Alternatively or additionally, the robotic lawnmower 100 may be arranged to communicate with a server (referenced 440 in figure 4A) for providing information regarding status, location, and progress of operation as well as receiving commands or settings.

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.

The robotic lawnmower 200 may further comprise 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. Alternatively 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.

The robotic lawnmower 200 may also or alternatively 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) information 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 is in some embodiments arranged to operate according to a map application of the work area 405 (and possibly the surroundings of the work area 405) stored in the memory 220 of the robotic lawnmower 200. The map application may be generated or supplemented as the robotic lawnmower 200 operates or otherwise moves around in the work area 405. In some embodiments, the map application includes one or more start regions and one or more goal regions for each work area. In some embodiments, the map application also includes one or more transport areas.

As discussed in the above, the map application is in some embodiments stored in the memory 220 of the robotic working tool(s) 200. In some embodiments the map application is stored in the server (referenced 440 in figure 4A). In some embodiments maps are stored both in the memory 220 of the robotic working tool(s) 200 and in the server, wherein the maps may be the same maps or show subsets of features of the area.

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), ranging sensors for enabling SLAM-based navigation (Simultaneous Localization and Mapping), moisture sensors, collision sensors, wheel load sensors to mention a few sensors.

Figure 3 shows a schematic view of a user equipment 300 according to an embodiment of the present invention. In one example embodiment, the viewing device 300 is a smartphone, smartwatch or a tablet computer. The user equipment 300 comprises a controller 301 a memory 302 and a user interface 310.

It should be noted that the user equipment 300 may comprise a single device or may be distributed across several devices and apparatuses.

The controller 301 is configured to control the overall operation of the user equipment 300 and specifically to execute a robotic working tool controlling application. In some embodiments, the controller 301 is a specific purpose controller. In some embodiments, the controller 301 is a general purpose controller. In some embodiments, the controller 301 is a combination of one or more of a specific purpose controller and/or a general purpose controller. As a skilled person would understand there are many alternatives for how to implement a controller, such as using Field - Programmable Gate Arrays circuits, ASIC, GPU, NPU etc. in addition or as an alternative. For the purpose of this application, all such possibilities and alternatives will be referred to simply as the controller 301.

The memory 302 is configured to store data such as application data, settings and computer-readable instructions that when loaded into the controller 301 indicates how the user equipment 300 is to be controlled. The memory 302 is also specifically for storing the robotic working tool controlling application and data associated therewith. The memory 302 may comprise several memory units or devices, but they will be perceived as being part of the same overall memory 302. There may be one memory unit for the robotic working tool controlling application storing instructions and application data, one memory unit for a display arrangement storing graphics data, one memory for the communications interface 303 for storing settings, and so on. As a skilled person would understand there are many possibilities of how to select where data should be stored and a general memory 302 for the user equipment 300 is therefore seen to comprise any and all such memory units for the purpose of this application. As a skilled person would understand there are many alternatives of how to implement a memory, for example using non-volatile memory circuits, such as EEPROM memory circuits, or using volatile memory circuits, such as RROBOTIC WORKING TOOL(S) memory circuits. For the purpose of this application all such alternatives will be referred to simply as the memory 302.

In some embodiments the user equipment 300 further comprises a communication interface 303. The communications interface 303 is configured to enable the user equipment 300 to communicate with robotic working tools, such as the robotic working tool of figures 2 A and 2B.

The communication interface 303 may be wired and/or wireless. The communication interface 303 may comprise several interfaces.

In some embodiments the communication interface 303 comprises a radio frequency (RF) communications interface. In one such embodiment the communication interface 303 comprises a Bluetooth™ interface, a WiFi™ interface, a ZigBee™ interface, a RFID™ (Radio Frequency IDentifier) interface, and/or other RF interface commonly used for short range RF communication. In an alternative or supplemental such embodiment the communication interface 303 comprises a cellular communications interface such as a fifth generation (5G) cellular communication interface, an LTE (Long Term Evolution) interface, a GSM (Global Systeme Mobile) interface and/or other interface commonly used for cellular communication. In some embodiments the communication interface 303 is configured to communicate using the UPnP (Universal Plug n Play) protocol. In some embodiments the communication interface 303is configured to communicate using the DLNA (Digital Living Network Appliance) protocol.

In some embodiments, the communication interface 303 is configured to enable communication through more than one of the example technologies given above. The communications interface 303 may be configured to enable the user equipment 300 to communicate with other devices, such as other smartphones.

The user interface 310 comprises one or more output devices and one or more input devices. Examples of output devices are a display arrangement, such as a display screen 310-1, one or more lights (not shown in figure 1 A) and a speaker (not shown). Examples of input devices are one or more buttons 310-2 (virtual 310-2 A or physical 310-2B), a camera (not shown) and a microphone (not shown). In some embodiments, the display arrangement comprises a touch display 310-1 that act both as an output and as an input device being able to both present graphic data and receive input through touch, for example through virtual buttons 310-2 A.

Using a user equipment a user is enabled to provide information on start regions, goal regions and transport areas to be used. The information may be location data defining the start regions, goal regions and/or transport areas. The information may alternatively or additionally be a selection of start regions, goal regions and/or transport areas.

Figure 4A shows a robotic work tool system 400 in some embodiments. The schematic view is not to scale. The robotic work tool system 400 of figure 4A, corresponds in many aspects to the robotic work tool system 100 of figure 1 A, except that the robotic work tool system 400 of figure 4A comprises two or more robotic work tools 200 according to the teachings herein. It should be noted that the work area shown in figure 4 is simplified for illustrative purposes but may contain some or all of the features of the work area of figure 1 A, and even other and/or further features as will be discussed below.

As with figures 2A and 2B, the robotic work tool(s) 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 two or more robotic working tools 200 of the robotic work tool system 400 are arranged to operate in a first work area 105 A and a second work area 105B.

The work area(s) 105 is in this application exemplified as a garden, but can also be other work areas as would be understood, such as an airfield. As discussed 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 work areas that are not essentially flat, but contain 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 alternatively arranged or configured to traverse and operate in a work area that contains obstacles that are not easily discerned 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 alternatively 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 work area 405 exemplified with referenced to figure 4A, may thus be such a non- uniform work area as disclosed in this paragraph that the robotic work tool is arranged to traverse and/or operate in. As shown in figure 4A, the robotic working tool(s) 200 is arranged to navigate through a transport area between two end regions, such as from a start region to a goal region.

In figure 4A the start and goal regions are both shown as being (oval) areas, but a region may have any shape or form, and also any range of extension, for example a singular point at one end of the range to the whole work area at the other end of the range.

The start and goal regions thus indicate a region where the robotic working tool(s) enters the transport area in a first work area 405 A and where the robotic working tool(s) 200 subsequently exits the transport area and arrives at the second work area 405B.

It should be noted that even though the transport area and how it is navigated herein is disclosed as being between two work areas 405, the transport area according to the teachings herein may also be used within a work area, where the transport area is from a first part of the work area to a second part of the work area.

The transport area is in some embodiments stored in or part of the map application discussed in the above.

The robotic working tool system 400 also comprises or is arranged to be connected to a user equipment 300, such as a user equipment 300 of figure 3. In some embodiments the robotic working tool 200 is arranged to be connected to the user equipment 300 directly and in some embodiments the robotic working tool 200 is arranged to be connected to the user equipment 300 indirectly.

The robotic working tool system 400 may alternatively or additionally comprise or be arranged to be connected to a server, such as a cloud service, a cloud server application or a dedicated server 440. The connection to the server 440 may be direct from the robotic working tool 200, direct from the user equipment, indirect from the robotic working tool 200 via the charging station, and/or indirect from the robotic working tool 200 via the user equipment 300.

As a skilled person would understand a server, a cloud server or a cloud service may be implemented in a number of ways utilizing one or more controllers 440A and one or more memories 440B that may be grouped in the same server or over a plurality of servers.

In some embodiments the server 440 is included in the user device 300. In some embodiments the user device 300 is an alternative to the server 440.

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.

In some embodiments the robotic working tool(s) 200 is configured to determine how to navigate through the transport area based on determinations made by the controller 210 of the robotic working tool(s). In some embodiments the robotic working tool(s) 200 is configured to determine how to navigate through the transport area based commands received from the server 440, which commands are based on determinations made by the controller 440A of the server 440.

In some embodiments the robotic working tool(s) 200 is configured to determine how to navigate through the transport area based commands received from the user device 300, which commands are based on determinations made by the controller 310 of the user device 300. In some embodiments the robotic working tool(s) 200 is configured to determine how to navigate through the transport area based on a combination of determinations made by the controller 210 of the robotic working tool(s) and on commands received.

In some embodiments, the controller 210 of the robotic working tool is configured to determine that a connection to server 440 is no longer active, and in response thereto make the determinations.

In some embodiments, the controller 210 of the robotic working tool is configured to determine that a connection to the user device 300 is no longer active, and in response thereto make the determinations.

The inventors have realized that in order to avoid collisions, congestions, blockings or other impediments, the transport area used should be assigned or associated with constraints, wherein the constraints relate to propulsion parameters which regulate or dictate how the robotic working tool(s) are to be propelled or navigated through the transport area. By utilizing such constraints trouble free navigation is enabled.

In some embodiments, and as shown in figure 4A, the transport area comprises two (or more) transport pathways TAI, TA2 through which the robotic working tool(s) 200 is allowed to travel between two regions, such as from a start region SR to a goal region GR.

In some embodiments a pathway TAI, TA2 is a sub area of the transport area TA. In some embodiments a pathway TAI, TA2 indicates an area where a transport path for a robotic working tool(s) that may be planned or travelled through the transport area TA, where the pathway has an extension perpendicular to a direction travelled allowing for more than one transport path to be planned or travelled. In some embodiments a pathway TAI, TA2 is a transport path for a robotic working tool(s) that may be planned or travelled through the transport area TA.

It should be noted that even though figure 4A shows two pathways TAI, TA2, any number (1, 2, 3, 4, 5, 6 or more) of pathways may be implemented.

In some embodiments a constraint for a (any, some or all) pathway is an allowed direction of travel through the pathway. In some such embodiments a first pathway has a constraint of a first direction of travel and a second pathway has a constraint of a second direction of travel. In some such embodiments, the first direction of travel is opposite the second direction of travel.

In figure 4A the first (upper) pathway TAI has the constraint of allowed travel in a direction from left to right. And the second (lower) pathway TA2 has the constraint of allowed travel in a direction from right to left. In such embodiments, the regions at the ends of the transport area, or more specifically at the ends of the pathways, are thus start regions and goal regions indicating where a robotic working tool(s) 20 enters a pathway TAI, TA2 in a first work area 405 A and where the robotic working tool(s) 200 exits the pathway TAI, TA2 in a second work area 405B.

In some embodiments a constraint for a (any, some or all) pathway is an allowed speed. In some such embodiments the allowed speed is a maximum speed that the robotic working tool(s) is not allowed to exceed. In some such embodiments the allowed speed is a minimum speed that the robotic working tool(s) is not allowed to exceed under.

In some embodiments the allowed speed is a constraint for one pathway. In some such embodiments a first allowed speed is for a first pathway and a second allowed speed is for a second pathway.

This will enable a robotic working tool that has entered a pathway to avoid collisions from behind (either colliding or being collided with) by propelling at the allowed speed as this reduces or eliminates the risk of one robotic working tool 200 running into another robotic working tool 200 from behind.

Figure 4B shows an example of transport area of a robotic working tool system 400 as in figure 4A, wherein there are four pathways TAI, TA2, TA3 and TA4. As in the example of figure 4A some pathways area may be associated with a direction of travel.

In this example it is shown a situation where a first pathway TAI has a constraint of a first allowed speed and a second pathway TA2 has a constraint of a second allowed speed, wherein the first allowed speed is lower than the second allowed speed whereby the robotic working tool(s) 200 travelling through the second pathway is able to overtake the robotic working tool(s) 200 travelling in the first pathway TAI without risk of any impediments, such as collision, congestion or blocking.

In some embodiments a constraint for a (any, some or all) pathway is an allowed number of robotic working tools 200 in a pathway at any given time. The number of allowed robotic working tools 200 is in some embodiments dependent on the size of a robotic working tool, the length of the pathway, the width of the pathway, the (average) speed of the robotic working tool and/or the allowed speed through the pathway.

In some embodiments a constraint for a (any, some or all) pathway is an allowed rate of entry for robotic working tools 200 into a pathway at any given time. The allowed rate of entry, i.e. the time between two rws entering a pathway, is in some embodiments dependent on the size of a robotic working tool, the length of the pathway, the width of the pathway, the (average) speed of the robotic working tool and/or the allowed speed through the pathway. By limiting the number of robotic working tools in a pathway, the risk of congestion and/or collision is reduced as this allows for a robotic working tool to handle any problems that are encountered without immediately being run into from behind.

In some embodiments a constraint for a (any, some or all) pathway is an allowed (minimum) distance D between robotic working tools 200 in a pathway at any given time. The allowed distance between robotic working tools 200 is in some embodiments dependent on the size of a robotic working tool, the length of the pathway, the width of the pathway, the (average) speed of the robotic working tool and/or the allowed speed through the pathway.

By limiting the minimum distance between robotic working tools in a pathway, the risk of congestion and/or collision is reduced as this allows for a robotic working tool to handle any problems that are encountered without immediately being run into from behind.

Figure 4C shows an example of transport area of a robotic working tool system 400 as in figure 4A, wherein it is shown how a first number of robotic working tool(s) is allowed into the first pathway TAI and how a second number of robotic working tools is allowed into the second pathway TA2. Figure 4C also shows how a robotic working tool 200 may have to wait - for example in or adjacent the start region until it is allowed to enter the pathway. The robotic working tool 200 maybe allowed to enter when the number of robotic working tools in the pathway is under the maximum allowed number, when the rate of entry is under the maximum allowed (i.e when the time between to robotic working tools is above the minimum allowed), when the distance to the next robotic working tool is above the minimum distance D or any of the other constraints discussed herein is fulfilled.

In some embodiments a constraint for a (any, some or all) pathway is an allowed width of the robotic working tool. The allowed width may be determined based on the width of the pathway.

In some embodiments a constraint for a (any, some or all) pathway is an allowed operation of the work tool 160, such as a maximum speed of the work tool 160 or whether the work tool 160 is to be used at all. In some embodiments a constraint for a (any, some or all) pathway is an allowed weight of the robotic working tool 200. This allows for a heavy robotic working tool to only be allowed to travel through pathways where it is safe for it to travel, while light robotic working tools may travel through more pathways.

In some embodiments a constraint for a (any, some or all) pathway is an allowed minimum power reserve (battery capacity, fuel level) before entering the pathway. This enables for reducing the risk of a robotic working tool being stranded in the pathway. The minimum power reserve may be determined based on the length of the pathway, the speed of the robotic working tool, or the expected time of traversing the pathway to mention a few factors.

In some embodiments a constraint for a (any, some or all) pathway is an allowed operating mode. In some such embodiments, the allowed operating mode is a silent operating mode, where the robotic working tool is operated in a manner that is more silent compared to normal operation. One such example is only allowing propulsion using electric motors in embodiments where both combustion and electric propulsion is available. One such example is not allowing operating of a work tool 160, the operating mode being an inactive mode.

In some embodiments a constraint for a (any, some or all) pathway is an allowed propulsion system. In some such embodiments a pathway may have a constraint as to the type of propulsion system that may be used in order to ensure that a robotic working tool is able to traverse the pathway, for example if the pathway is known to be very slippery, only robotic working tools capable of navigating slippery surface may be allowed to enter, such as robotic working tools operating with caterpillar tracks. A first pathway may thus allow a first propulsion system, whereas a second pathway may allow a second propulsion system.

In some embodiments a constraint for a (any, some or all) pathway is based on a current weather. The current weather may be determined through environmental sensors. Alternatively or additionally, the current weather may be received from a weather report service. The weather report may be received directly by the robotic working tool from the weather report service or indirectly from the server and/or another robotic working tool. As different weather types may affect the terrain in a pathway, a constraint may be determined based on the weather to ensure a safe and reliable passage. For example, during rain, the lawn may become slippery and/or “heavier” to drive through (higher rolling resistance), and a constraint relating to the speed may thus be adjusted or determined based on the weather.

Alternatively or additionally, a constraint may be based on environmental factors that may be received and determined through sensors, or received and determined indirectly via the server and/or another robotic working tool. For example odometers may be used to discover wheel slip indicative of a muddy tack, which may require a slower speed to traverse, or only robotic working tools with a certain wheel diameter, climbing ability and/or clearance.

In some embodiments a constraint for a (any, some or all) pathway is related to the physical properties of the robotic working tool, in that a maximum weight of the robotic working tool is allowed for a pathway, thereby ensuring that heavy robotic working tools ado not enter pathways where the heavy vehicle may get stuck, such as in a pathway where there is muddy areas and/or areas of loose sand.

In some embodiments a constraint for a (any, some or all) pathway is related to allowable maneuvers. For example in one pathway any robotic working tool entering may only be allowed to propel in a straight line, that is a line that follows the curvature of the pathway. Another example is a pathway where the robotic working tool entering the pathway is allowed to zig-zack. Yet another example is a pathway where the robotic working tool entering the pathway is allowed to turn, perhaps in order to avoid an obstacle, or even to turn and return through the same pathway. Yet another example is a pathway where the robotic working tool entering the pathway is allowed to reverse.

It should be noted that any, some or all of the constraints discussed in the above may be combined in any embodiment, even if not explicitly disclosed herein as combined.

In some embodiments the robotic working tool is configured to make determinations of a condition of a transport area or of a pathway in the transport area and determine constraints for the transport area or the pathway based on the condition. In some such embodiments, the determination is based on sensor input. In some such embodiments the robotic working tool is configured to report any determinations of conditions or the sensor input to the server and/or the user device for enabling correct determinations to be made regarding the navigation through a pathway.

In some such embodiments the robotic working tool is configured to determine that a pathway is blocked or otherwise unable to be traversed, whereby the pathway is associated with the constraint of no allowed travel. The robotic working tool may determine that the pathway is blocked based on collision sensors 290 or optical sensors 290 sensing a blocking object in front of the robotic working tool.

In some such embodiments the robotic working tool is configured to determine that a pathway is partially blocked, whereby the pathway is associated with the constraint of a maximum width based on the object partially blocking the pathway.

In some such embodiments the robotic working tool is configured to determine that a pathway is wet or otherwise showing an increased risk of slipping, whereby the pathway is associated with the constraint of an allowed maximum speed, maximum acceleration and/or maximum turning. The robotic working tool may determine that the pathway is wet based on moisture sensors 290 or optical sensors 290.

It should be noted that even though the pathways are all shown as being adjacent one another in the figures, other variants are possible and part of the teachings herein. In some embodiments two pathways are overlapping one another. In some embodiments two pathways are above one another (such as on different floors, levels or planes).

It should also be noted that even though the pathways and transport paths are all shown as being non-linear, they can be any shape including straight, curved, zig-zag, random, semi-random to mention a few examples.

In some embodiments, the controller is configured to determine the pathways and/or the constraints based on the map application of the work area, the number of robotic working tools and/or the properties of the robotic working tools so as to enable optimum transport paths to be determined. For example, there is no need for multiple pathways in both directions if only two robotic working tools are operating in the work area(s)

The robotic working tool, the server and/or the user device is thus enabled to determine a transport path to be taken for a robotic working tool through the transport area based on the constraints, which allows for determining an optimum collision free path.

The transport paths, the pathways and the constraints may be shared between the robotic working tool(s), the server 440 and/or the user device.

As discussed in the above, the robotic working tool may be configured to determine that a pathway is at least partially blocked. The robotic working tool may also or additionally in some embodiments be configured to determine that an event occurs in the pathway or generally I the transport area, i.e. the robotic working tool is configured to detect an event in a pathway and to adapt the constraints based on the detected event.

Examples of such events will be discussed in relation to figure 4D. Figure 4D shows an example of transport area of a robotic working tool system 400 as in figure 4A, wherein two example situations of events that may occur or be detected are shown.

In some embodiments the event detected is that an object is encountered in the pathway or transport area. In one example the object detected is another robotic working tool that is caught up with. In such an embodiment, the robotic working tool is then configured - either directly or remotely by transmitting information to the server - to determine new or update constraints for that pathway. Generally such updated or new constraints are to avoid the robotic working tool colliding with the other robotic working tool. One such update or new constraint is a maximum speed for the robotic working tool (or alternatively or additionally a minimum speed for the other robotic working tool). In one example the object detected is another robotic working tool that is on a collision course or collided with. In such an embodiment, the robotic working tool is then configured - either directly or remotely by transmitting information to the server - to determine new or update constraints for that pathway. One such update or new constraint is an allowed direction for the robotic working tool (or alternatively or additionally for the other robotic working tool), which may cause the robotic working tool to change pathways or to reverse out of the pathway.

Alternatively, the robotic working tool is configured to halt operation, observe the/any movements of the object encountered (i.e. generate movement data through sensor input) and then adapt its movement and/or constraints based on the observed movements. For example if a stationary (non-moving) object is encountered, it may simply be navigated around. If a moving object is encountered, the robotic working tool may - either directly or remotely by transmitting information to the server - adapt its movement so as to avoid a collision by adapting navigation and/or speed.

In some such embodiments, the observation of the object may include visual observation through an image sensor, part of the sensors, providing image data which image data is analysed by the robotic working tool- either directly or remotely by transmitting information to the server - to determine or classify the object, whereby a movement pattern for the robotic working tool may be devised. The movement of the robotic working tool, i.e. its constraints, may thus be based on the classification. For example if the object is determined to be an animal, such as a hedgehog, the movement for the robotic working tool may be determined to halt and wait until the animal is no longer in the path of the robotic working tool. Another example is where the object is a football, whereby the movement for the robotic working tool may be to rotate until a person (adult or child) to whom the football assumingly belongs to, and then adapt the movement so that the person is avoided. Possibly by simply not moving until the person is no longer in the vicinity of the robotic working tool.

In some embodiments the robotic working tool is configured to detect the event and in response thereto inform the server, which then caused by the notification analyses the situation and informs the robotic working tool and/or other robotic working tools of possible actions to take, and possibly updates constraints for the affected pathways.

In some embodiments the event detected is that an environmental factor or a current weather changes, such as that the pathway is detected to be more slippery than anticipated or that it starts to rain. The robotic working tool is then configured - either directly or remotely by transmitting information to the server - to determine new or update constraints for that pathway.

In some embodiments the event detected is that a component of the robotic working tool is malfunctioning, such as a cutting blade being damaged or the propulsion system being impaired. The robotic working tool is then configured - either directly or remotely by transmitting information to the server - to determine whether it is possibly to return to a service station and if so do so. The robotic working tool is alternatively configured - either directly or remotely by transmitting information to the server - to determine that it is able to exit the pathway, and then exit the pathway, move to a side so as to not block the pathway entrance/exit and then halt. In some embodiments the event detected is that a component of the robotic working tool is caught up by another robotic working tool, whereby the robotic working tool is configured - either directly or remotely by transmitting information to the server - to determine that it should move to a side of the pathway so as to allow the other robotic working tool to pass.

In some embodiments the event detected is that the robotic working tool will not be able to exit the pathway (as planned). This may be due to an actual speed being lower than expected (possibly due to a higher roling resistance), due to a higher energy consumption (possibly due to a higer rolling resistance and/or cutting resistance), due to an extended time spent in the pathway (possibnly due to encountering an object forcing the robotic working tool to stop or bypass the detected object). In some embodiments the robotic working tool is then configured - either directly or remotely by transmitting information to the server - to determine a shortest path out of the pathway, navigate such pathway and then stop. In some embodiments the robotic working tool is then configured - either directly or remotely by transmitting information to the server - to reverse or follow the path already travelled out of the pathway. In some embodiments the robotic working tool is then configured - either directly or remotely by transmitting information to the server - to adjust a constraint, such as a speed, to enable for an extended operating time due to a lower energy consumption.

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.

As discussed in the above, a controller of the system determines 510 a transport path for a robotic working tool 200, or in other words, how the robotic working tool 200 is to be navigated through a transport area TA so as to avoid collisions or other impediments. The determination is based on a number of pathways that are determined 520 and on constraints for the pathways that are also determined 530 for the pathway. The constraints are in some embodiments based on conditions that are determined 540.

As a skilled person would understand, some or all of the determinations are, in some embodiments, performed by the robotic work tool 200 alone, or by the robotic work tool 200 in collaboration with the serer 400. All features of the embodiment disclosed herein thus apply equally to the system of the server and the two or more robotic work tools, as well as to a robotic work tool acting in accordance. Specifically, a robotic work tool comprising a controller is provided, wherein the robotic work tool is configured to operate as the robotic work tool 200 of any of the systems above.

In some embodiments the robotic work tool 200 comprises at least one memory 220 configured to store information about the transport area TA, wherein the controller 210 is configured to: receive, from the at least one memory 220, information about the transport area TA; and navigate the robotic work tool 200 between the first end region GR, SR and the second end region 330 based on said constraints in order to avoid possible collisions between and/or blockings of at least one of the two or more robotic work tools. The navigation may be made in any manner as discussed herein.

In some embodiments the controller is further configured to determine that the robotic work tool 200 is to enter the transport area, and in response thereto transmit an indicator of the robotic work tool 200 to the server 440; receive said constraints from said server 440; compare the constraints with parameters for the robotic work tool 200, and, if the constraints are within the parameters, navigate the transport area. In some such embodiments, the indicator is an identifier of the robotic work tool 200. Such an identifier may be a serial number in some embodiments. In some embodiments, the identifier may be a type indicator, a server receiving such an indicator of the robotic work tool, will thus be able to determine poperites and other characteristics of the robotic work tool and determine suitable constraints based on such porperties. The properties may relate to a maximum speed, minimum turning radius, maximum climbing ability, physical properties (width, weight, wheel size, and so on), range (battery time remaining, fuel remaining) to mention a few examples.

In some embodiments the controller is further configured to transmit an acceptance to the server 440 if the constraints are within the parameters. This in order to allow the server to plan work of other robotic work tools and/or to re-plan the constraints for the robotic work tool 200. In some embodiments the constraints are based on the properties of the robotic work tool 200. Wherein the constraints are specifically designed for the robotic work tool 200.

It is also an object of the teachings of this application to overcome the problems by providing a method for use in robotic work tool for implementing a robotic work tool for use in the system according to herein. The flowchart of figure 5 thus equally apply to the robotic work tool 200 as to the robotic work tool system 400.