SE546086C2 - Robotic lawnmower arranged to operate in an operational area and a method therefor - Google Patents

Robotic lawnmower arranged to operate in an operational area and a method therefor

Info

Publication number
SE546086C2
SE546086C2 SE2250281A SE2250281A SE546086C2 SE 546086 C2 SE546086 C2 SE 546086C2 SE 2250281 A SE2250281 A SE 2250281A SE 2250281 A SE2250281 A SE 2250281A SE 546086 C2 SE546086 C2 SE 546086C2
Authority
SE
Sweden
Prior art keywords
robotic
1awnmower
sensor
grass
ground
Prior art date
Application number
SE2250281A
Other languages
Swedish (sv)
Other versions
SE2250281A1 (en
Inventor
Rickard Landin
Original Assignee
Husqvarna Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Husqvarna Ab filed Critical Husqvarna Ab
Priority to SE2250281A priority Critical patent/SE546086C2/en
Priority to PCT/SE2022/051199 priority patent/WO2023167617A1/en
Publication of SE2250281A1 publication Critical patent/SE2250281A1/en
Publication of SE546086C2 publication Critical patent/SE546086C2/en

Links

Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C22/00Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1/00Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
    • G05D1/02Control of position or course in two dimensions
    • G05D1/021Control of position or course in two dimensions specially adapted to land vehicles
    • G05D1/0268Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means
    • G05D1/027Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means comprising intertial navigation means, e.g. azimuth detector
    • AHUMAN NECESSITIES
    • A01AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01DHARVESTING; MOWING
    • A01D34/00Mowers; Mowing apparatus of harvesters
    • A01D34/006Control or measuring arrangements
    • A01D34/008Control or measuring arrangements for automated or remotely controlled operation
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01CMEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
    • G01C21/00Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
    • G01C21/10Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration
    • G01C21/12Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning
    • G01C21/16Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration executed aboard the object being navigated; Dead reckoning by integrating acceleration or speed, i.e. inertial navigation
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1/00Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
    • G05D1/02Control of position or course in two dimensions
    • G05D1/021Control of position or course in two dimensions specially adapted to land vehicles
    • G05D1/0268Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means
    • G05D1/0274Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means using mapping information stored in a memory device
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1/00Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
    • G05D1/02Control of position or course in two dimensions
    • G05D1/021Control of position or course in two dimensions specially adapted to land vehicles
    • G05D1/0276Control of position or course in two dimensions specially adapted to land vehicles using signals provided by a source external to the vehicle
    • G05D1/0278Control of position or course in two dimensions specially adapted to land vehicles using signals provided by a source external to the vehicle using satellite positioning signals, e.g. GPS
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1/00Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
    • G05D1/20Control system inputs
    • G05D1/24Arrangements for determining position or orientation
    • G05D1/247Arrangements for determining position or orientation using signals provided by artificial sources external to the vehicle, e.g. navigation beacons
    • G05D1/248Arrangements for determining position or orientation using signals provided by artificial sources external to the vehicle, e.g. navigation beacons generated by satellites, e.g. GPS
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D2111/00Details of signals used for control of position, course, altitude or attitude of land, water, air or space vehicles
    • G05D2111/50Internal signals, i.e. from sensors located in the vehicle, e.g. from compasses or angular sensors
    • G05D2111/52Internal signals, i.e. from sensors located in the vehicle, e.g. from compasses or angular sensors generated by inertial navigation means, e.g. gyroscopes or accelerometers
    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05DSYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D2111/00Details of signals used for control of position, course, altitude or attitude of land, water, air or space vehicles
    • G05D2111/50Internal signals, i.e. from sensors located in the vehicle, e.g. from compasses or angular sensors
    • G05D2111/54Internal signals, i.e. from sensors located in the vehicle, e.g. from compasses or angular sensors for measuring the travel distances, e.g. by counting the revolutions of wheels

Landscapes

  • Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Control Of Position, Course, Altitude, Or Attitude Of Moving Bodies (AREA)
  • Guiding Agricultural Machines (AREA)

Abstract

A method for use in a robotic lawnmower (100) arranged to operate in an operational area, the robotic lawnmower comprising a work tool (160), a navigation sensor, and a grass sensor, wherein the signal-based navigation sensor is configured to provide a current location of the robotic lawnmower (100), wherein the grass sensor is configured to provide a determination of whether the robotic lawnmower is currently operating on grass or not, and wherein the method comprises: causing the robotic lawnmower (100) to operate in the operational area with the work tool (160) active; determining that the navigation sensor is unable to provide an accurate location; determining whether the robotic lawnmower is currently operating on grass or not based on the grass sensor, and if so, continuing operating with the work tool active, and if not so, continuing operating with the work tool deactivated.

Description

TECHNICAL FIELD This application relates to a robotic laWnmoWer and in particular to a system and a method for providing an improved operation for robotic laWnmoWers in such a system.
BACKGROUND Automated or robotic laWnmoWers are becoming increasingly more popular and as the robotic laWnmoWers become more and more advanced so are the areas they are deployed Within as Well. The operational areas are not only becoming bigger and bigger, but are also comprising more and more features. This makes the mapping of the area more and more important to enable for a proper operation in the operational area.
As the areas grow, both in size and complexity, the navigation of a robotic laWnmoWer has become more and more reliant on advanced navigation techniques such as satellite navigation or other map-based navigation techniques, as opposed to the more standard of using a boundary Wire to provide boundaries for an operating area.
HoWever, as operating areas are including more and more features, the risk of entering a so-called satellite shadow area (an area Where the satellite signals are not received at a high enough quality (or number of signals) that an accurate position may be determined), the risk for the robotic laWnmoWer losing its position also increases. As a standard safety precaution, a robotic laWnmoWer is generally adapted to stop operating When it is no longer able to accurately determine its position, be it by satellite navigation or other means.
A solution has been to equip a robotic laWnmoWer With sensors for deduced reckoning, but these may also fail to provide an accurate enough position, and often also rely on the same safety precaution of suspending operation.
One such solution is discussed in the patent application published as WO2020l43972Al disclosing a method of navigating a self-propelled robotic tool Within a Work area defined by a boundary comprises determining a positioning status comprising a position of the robotic tool Within the area; based on the detern1ined position of the robotic tool, estimating a boundary distance value indicative of a distance from the robotic tool to the boundary; setting a maximum dead reckoning navigation distance based on the boundary distance value; if a new positioning status cannot be reliably obtained, continuing navigating the robotic tool based on dead reckoning; and if no new positioning status of the robotic tool Within the area has been reliably obtained upon reaching the maximum dead reckoning navigation distance, executing a safety operation based on having reached the maximum dead reckoning navigation distance.
Suspending the operation Will both Waste time and appear to a user as there is something Wrong With the robotic laWnmoWer.
Thus, there is a need for an improved manner of operating in operational areas Where there is a risk of shadoWed navigation areas.
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 laWnmoWer arranged to operate in an operational area, the robotic laWnmoWer comprising a Work tool, a navigation sensor, a ground sensor and a controller, Wherein the signal-based navigation sensor is configured to provide a current location of the robotic laWnmoWer, Wherein the ground sensor is configured to provide a deterrr1ination of Whether the robotic laWnmoWer is currently operating on permitted ground or not, and Wherein the controller is configured to: cause the robotic laWnmoWer to operate in the operational area With the Work tool active; determine that the navigation sensor is unable to provide an accurate location; determine Whether the robotic laWnmoWer is currently operating on permitted ground or not based on the ground sensor, and if so, continue operating With the Work tool active, and if not so, continue operating With the Work tool deactivated.
In some embodiments the controller is further configured to determine that the robotic laWnmoWer is again operating on permitted ground, and in response thereto continue operating With the Work tool activated.
In some embodiments the robotic laWnmoWer further comprises at least one deduced reckoning sensor and Wherein the controller is further configured to continue operating by performing a planned path utilizing the deduced reckoning sensor In some embodiments the robotic laWnmoWer further comprises at least one deduced reckoning sensor and Wherein the controller is further configured to continue operating by returning along a travelled path utilizing the deduced reckoning sensor In some embodiments the robotic laWnmoWer further comprises at least one deduced reckoning sensor and Wherein the controller is further configured to continue operating by eXecuting an at least semi-random path utilizing the deduced reckoning sensor In some embodiments the controller is further configured to continue operating by eXecuting a zigzag pattern.
In some embodiments the controller is further configured to continue operating based on the grass sensor, Whereby the controller is further configured to tum back When the grass sensor indicates that the robotic laWnmoWer Will no longer be operating on permitted ground if the robotic laWnmoWer continues ahead.
In some embodiments the controller is further configured to determine that the navigation sensor is again able to provide an accurate location, and in response thereto determine a current location of the robotic laWnmoWer and determine if the current location of the robotic laWnmoWer is outside the operational area, and if so return to the operational area.
In some embodiments the controller is further configured to return along a travelled path.
In some embodiments the controller is further configured to determine a shortest path to the operational area and return along the shortest path.
In some embodiments the ground sensor comprises a grass sensor, and Wherein the permitted ground includes grass.
In some embodiments the grass sensor is further configured to determine the height of the grass and, Wherein the controller is further configured to determine Whether the robotic laWnmoWer is currently operating on grass or not based on the grass sensor by deterrnining that the robotic laWnmoWer is currently operating on grass of a height falling Within a desired range.
In some embodiments the desired range corresponds to the height of the grass cut prior to deterrnining that the navigation sensor is unable to provide an accurate location.
In some embodiments the desired range is up to 1.5 times the height of the grass cut.
In some embodiments the desired range corresponds to the height of the Work tool.
In some embodiments the desired range is up to 15 cm. In some embodiments the desired range is up to 10 cm. In some embodiments the desired range is over 2 mm. In some embodiments the desired range is from 4 mm up to 8 mm.
In some embodiments the grass sensor is further configured to determine the type of the grass and, Wherein the controller is further configured to determine Whether the robotic laWnmoWer is currently operating on grass or not based on the grass sensor by detern1ining that the robotic laWnmoWer is currently operating on grass of a type falling Within a desired type.
In some embodiments the ground sensor comprises a gravel sensor, a sand sensor and/or a paved path sensor, and Wherein the permitted ground includes gravel, sand and/or paved path.
It is also an object of the teachings of this application to overcome the problems by providing a method for use in a method for use in a robotic laWnmoWer arranged to operate in an operational area, the robotic laWnmoWer comprising a Work tool, a navigation sensor, and a ground sensor, Wherein the signal-based navigation sensor is configured to provide a current location of the robotic laWnmoWer, Wherein the ground sensor is configured to provide a deterrnination of Whether the robotic laWnmoWer is currently operating on permitted ground or not, and Wherein the method comprises: causing the robotic laWnmoWer to operate in the operational area With the Work tool active; determining that the navigation sensor is unable to provide an accurate location; deterrnining Whether the robotic laWnmoWer is currently operating on permitted ground or not based on the ground sensor, and if so, continuing Operating With the work tool active, and if not so, continuing operating with the work tool deactivated.
Further embodiments and aspects are as in the attached patent claims and as discussed in the detailed description.
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 lA shows an example of a robotic lawnmower according to some embodiments of the teachings herein; Figure lB shows a schematic view of the components of an example of a robotic lawnmower according to some example embodiments of the teachings herein; Figure 2 shows a schematic view of a robotic lawnmower system according to some example embodiments of the teachings herein; Figure 3A shows a schematic view of a robotic lawnmower system according to some example embodiments of the teachings herein; Figure 3B shows a schematic view of a robotic lawnmower system according to some example embodiments of the teachings herein; Figure 3C shows a schematic view of a robotic lawnmower system according to some example embodiments of the teachings herein; and Figure 4 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 lawnmowers where a work tool is to be safeguarded against from accidentally extending beyond or too close to the edge of the robotic lawnmower.
Figure 1A shows a perspective view of a robotic lawnmower 100. The example of figure 1A (and the other figures) has a body 140 and a plurality of wheels 130 (only one side is shown). The robotic lawnmower 100 may be a multi-chassis type or a mono- chassis type (as in figure 1A). 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 even more than 1 meter 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 or robotic golfball collectors to mention a few examples.
It should also be noted that the robotic lawnmower is a self-propelled robotic lawnmower, capable of autonomous navigation within a work area, where the robotic lawnmower propels itself across or around the work area in a pattern (random or predeterrnined) .
Figure 1B shows a schematic overview of the robotic lawnmower 100. In this example embodiment the robotic lawnmower 100 is of a mono-chassis type, having a main body part 140. The main body part 140 substantially houses all components of the robotic laWnmoWer 100. The robotic laWnmoWer 100 has a plurality of Wheels 130. In the exemplary embodiment of figure 1B the robotic laWnmoWer 100 has four Wheels 130, two front Wheels and tWo rear Wheels. At least some of the Wheels 130 are drivably connected to at least one electric motor 150. 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 1B, each of the Wheels 130 is connected to a common or to a respective electric motor 155 for driving the Wheels 130 to navigate the robotic laWnmoWer 100 in different manners. The Wheels, the motor 155 and possibly the battery 150 are thus examples of components making up a propulsion device. By controlling the motors 150, the propulsion device may be controlled to propel the robotic laWnmoWer 100 in a desired manner, and the propulsion device Will therefore be seen as synonymous With the motor(s) It should be noted that Wheels 130 driven by electric motors is only one example of a propulsion system and other variants are possible such as caterpillar tracks.
The robotic laWnmoWer 100 also comprises a controller 110 and a computer readable storage medium or memory 120. The controller 110 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 120 to be executed by such a processor. The controller 110 is configured to read instructions from the memory 120 and execute these instructions to control the operation of the robotic laWnmoWer 100 including, but not being limited to, the propulsion and navigation of the robotic laWnmoWer.
The controller 110 in combination With the electric motor 155 and the Wheels 130 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 1A, The controller 110 may be implemented using any suitable, available processor or Programmable Logic Circuit (PLC). The memory 120 may be implemented using any commonly knoWn technology for computer-readable memories such as ROM, FLASH, DDR, or some other memory technology.
The robotic lawnmower 100 is further arranged with a wireless communication interface 115 for communicating with other devices, such as a server, a personal computer, a smartphone, the charging station, and/or other robotic lawnmowers. Examples of such Wireless communication devices are B1uetooth®, 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 200 as discussed in relation to figure 2 below for providing information regarding status, location, and progress of operation to the user equipment 200 as well as receiving commands or settings from the user equipment 200. Altematively or additionally, the robotic lawnmower 100 may be arranged to communicate with a server (referenced 240 in figure 2) for providing information regarding status, location, and progress of operation as well as receiving commands or settings.
The robotic lawnmower 100 also comprises a grass cutting device 160, such as a rotating blade 160 driven by a cutter motor 165. The grass cutting device being an example of a work tool 160 for a robotic work tool 100. In the example of a robotic watering tool, the work tool is the watering arrangement, and in the example of the robotic golfball collector, the work tool is the ball collector.
The robotic lawnmower 100 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 185. 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 100 is arranged with a navigation sensor, the magnetic sensors 170 as will be discussed below are optional. ln 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 120 of the robotic laWnmoWer 100. The virtual Work area may be defined by a virtual boundary.
The robotic laWnmoWer 100 may also or alternatively comprise deduced reckoning sensors 180. The deduced reckoning sensors may be odometers, accelerometers 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 100 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 100 is, in some embodiments, further configured to have at least one magnetic field sensor 170 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 170 may be connected to the controller 110, possibly via filters and an amplifier, and the controller 110 may be configured to process and evaluate any signals received from the sensors 170. The sensor signals are caused by the magnetic field being generated by the control signal being transn1itted through the boundary Wire. This enables the controller 110 to determine Whether the robotic laWnmoWer 100 is close to or crossing the boundary Wire, or inside or outside an area enclosed by the boundary Wire.
As mentioned above, in some embodiments, the robotic laWnmoWer 100 is in some embodiments arranged to operate according to a map application representing one or more Work areas (and possibly the surroundings of the Work area(s)) stored in the memory 120 of the robotic laWnmoWer 100. The map application may be generated or supplemented as the robotic laWnmoWer 100 operates or otherwise moves around in the Work area 205. 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 120 of the robotic working tool(s) 100. In some embodiments the map application is stored in the server (referenced 240 in figure 2). In some embodiments maps are stored both in the memory 120 of the robotic working too1(s) 100 and in the server, wherein the maps may be the same maps or show subsets of features of the area.
The robotic working tool 100 also comprises ground sensors 190 for enabling a deterrnination of what type of ground the area currently being operated on is of.
It should be noted that even if the disclosure herein is focussed on the example of deterrnining that grass is being operated upon, a designer and/or an operator may determine other types of grounds that operation is permitted on - even without an accurate location fix. Examples of such permitted grass are grass, gravel, sand to mention a few examples.
In some embodiments the ground sensor 190 comprises a camera that is configured to capture one or more images of the area being operated and to determine based on image analysis, possibly with an onboard processor or in combination with the controller 110, determine what type of ground the area being operated is covered with - at least in front and/or under the robotic lawnmower - based on image processing.
In some embodiments the ground sensors 190 comprises grass sensors for enabling a determination of whether the area currently being operated on is of grass, and in some embodiments, is of grass of a certain height.
In some such embodiments the grass sensor 190 comprises the grass cutter 160 and the grass sensor 190 is configured to determine the load exerted on the grass cutter 160, for example by monitoring the load on the cutter motor 165 or the power supplied to the cutter motor 165. By determining the load, it can be determined that grass is currently being operated upon. It can also be determined the height and/or type/thickness of the grass being operated upon.
In some embodiments where the ground sensor (or rather the grass sensor) 190 comprises a camera, the grass sensor is further configured to determine the height of the grass being cut, based on image processing. ll In some alternative or additional such embodiments the grass sensors 190 comprises a capacitive sensor that based on the capacitance under the robotic lawnmower detern1ines whether there is grass or not.
It should be noted that a grass sensor 190 may comprise, one, some or all of these examples Working in combination to determine that grass is being operated upon, and in some embodiments the type of grass and/or the height of the grass.
In some embodiments the ground sensors 190 comprises gravel sensors for enabling a determination of whether the area currently being operated on is of gravel.
In some embodiments the ground sensors 190 comprises sand sensors for enabling a determination of whether the area currently being operated on is of sand.
In some embodiments the ground sensors 190 comprises paved path sensors for enabling a determination of whether the area currently being operated on is a paved path.
It should be noted that a ground sensor 190 may comprise, one, some or all of the ground sensor examples Working in combination to determine what type of ground is being operated upon, to enable a deterrnination of whether the ground is of a permitted type or not.
Figure 2 shows a robotic lawnmower system 200 in some embodiments. The schematic view is not to scale. The robotic lawnmower system 200 comprises one or more robotic lawnmowers 100 according to the teachings herein. It should be noted that the operational area 205 shown in figure 2 is simplified for illustrative purposes. The robotic lawnmower system comprises a boundary 220 that may be Virtual and/or electro mechanical such as a magnetic field generated by a control signal being transmitted through a boundary wire, and which magnetic field is sensed by sensor in the robotic lawnmower The robotic lawnmower system 200 further comprises a station 210 possibly at a station location. A station location may alternatively or additionally indicate a service station, a parking area, a charging station or a safe area where the robotic lawnmower may remain for a time period between or during operation session.
As with figures 1A and lB, the robotic lawnmower(s) is eXemplified by a robotic lawnmower, whereby the robotic lawnmower system may be a roboticlawnmower system or a system comprising a combinations of robotic lawnmowers, one being a robotic lawnmower, but the teachings herein may also be applied to other robotic lawnmowers adapted to operate within a work area.
The one or more robotic working tools 100 of the robotic lawnmower system 200 are arranged to operate in an operational area 205, which in this example comprises a first work area 205A and a second work area 205B connected by a transport area TA. However, it should be noted that an operational area may comprise a single work area or one or more work areas, possibly arranged adjacent for easy transition between the work areas, or connected by one or more transport paths or areas, also referred to as corridors. In the following work areas and operational areas will be referred to interchangeably, unless specifically indicated.
The operational area 205 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 lawnmower 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 lawnmower and the ground. The robotic lawnmower is also or alternatively arranged or configured 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 lawnmower 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 work area 205 eXemplified with referenced to figure 2, may thus be such a non-uniforrn work area as disclosed in this paragraph that the robotic lawnmower is arranged to traverse and/or operate in.As shown in figure 2, the robotic working tool(s) 100 is arranged to navigate in one or more work areas 205A, 205B, possibly connected by a transport area TA.
The robotic working tool system 200 may altematively or additionally comprise or be arranged to be connected to a server 240, such as a cloud service, a cloud server application or a dedicated server 240. The connection to the server 240 may be direct from the robotic working tool l00, direct from a user equipment 250, indirect from the robotic working tool l00 via the service station 2l0, and/or indirect from the robotic working tool l00 via the user equipment As a skilled person would understand that a server, a cloud server or a cloud service may be implemented in a number of ways utilizing one or more controllers 240A and one or more memories 240B that may be grouped in the same server or over a plurality of servers.
The inventors have realized that as long as the robotic lawnmower is operating on grass, there is no significant risk in allowing the robotic lawnmower to continue operating.
Figure 3A shows a simplified view of a robotic lawnmower system 200 in an operational area 205 as in figure 2. Figure 3A shows how a robotic lawnmower l00 operates in an operational area 205. The operational area 205 comprises a number of features, which in this example, are two trees referenced T, three stones referenced S and a house referenced H. The operational area is also enclosed by a boundary 220, which may be virtual, magnetic, optical or any combination thereof, the boundary also being an example of a feature.as a skilled person would understand, these features are only examples and the teachings herein apply also to other types of features. In figure 3A the operational area is mainly covered with grass, as is indicated by the dotted areas, and as is shown the grass extends outside the boundary 220. The grass is one example of a ground type that is or may be set to be permitted. As an example of other ground types (for example gravel, paved paths, sand to mention a few) that is or may be set to be permitted a gravel path GP is also shown in figure 3A. As with the grass, the gravel path GP extends outside the boundaryAlso shown in figure 3A is a shadowed area 206, such as an area where GPS or RTK signals are not readily received to provide for an accurate determination of a location.
In some embodiments the controller possibly through the satellite navigation sensor may be configured to deterrnine that the location is not accurate if the accuracy falls below a threshold value.
In some embodiments the controller possibly through the satellite navigation sensor may be configured to determine that the location is not accurate if the quality of the signals received falls below a signal quality threshold value.
In some embodiments the controller possibly through the satellite navigation sensor may be configured to determine that the location is not accurate if the number of signals received falls below a signal number threshold value.
As a skilled person would understand, any, some or all of these examples may be combined to determine that a location is not accurately determined.
The operation of the robotic lawnmower 100 according to herein will now be discussed in relation to figures 3A and 3B as well as figure 4. Figure 4 shows a flowchart for a general method according to herein. The method is for use in a robotic lawnmower as in figures 1A and 1B.
In the example of figure 3A, the robotic lawnmower 100 is operating 410 in the operational area 205 navigating based on the signal-based navigation system of a GPS or RTK system and the robotic lawnmower 100 has entered the shadowed area 206 with the work tool 160 active. As the robotic lawnmower enters the shadowed area it deterrnines 420 that the navigation sensor 185 is unable to provide an accurate location. And, in response thereto the robotic lawnmower 100 determines 430 whether the robotic lawnmower 100 is currently operating on a ground type that is permitted based on the ground sensor 190, and if so, continue 440 operating with the work tool active. If it is determined that the robotic lawnmower 100 is not operating on permitted ground, the robotic lawnmower 100 either stops operating or attempts to deterrnine a location again, as in prior art systems with the work tool deactivated. That is the robotic lawnmower 100 continues operating 435 with the work tool deactivated. In some embodiments, and as discussed in relation to figure 1B, the permitted ground includes grass. In some such embodiments the deterrnination whether the ground is permitted is a deterrnination if grass is being operated on. This allows the robotic lawnmower 100 to continue operating while in the shadowed area 206 without causing a stop which would be confusing to a user and/or require a manual restart of the robotic lawnmower 100. In some embodiments, and as discussed in relation to figure 1B, the permitted ground includes one, some or all of grass, gravel, sand and/or paved paths. This also allows the robotic lawnmower 100 to continue operating while in the shadowed area 206, such as over the gravel path GP, without causing a stop which would be confusing to a user and/or require a manual restart of the robotic lawnmower As the robotic lawnmower 100 moves around to try and determine a location, the robotic lawnmower 100 may again happen to continue over grass (and/or other permitted type of ground). In some embodiments the controller is further configured to determine that the robotic lawnmower is again 445 operating on grass (and/or other permitted type of ground), and in response thereto continue operating with the work tool activated.
Figure 3B also shows a schematic view of a robotic lawnmower system 200 as in figure 3A. However, in the example situation of figure 3B, the robotic lawnmower 100 has by chance eXited the operational area 205, but is still operating on grass, as is indicated by the dotted area in figure 3B, and thus continues operating.
As mentioned in relation to figure lB, the robotic lawnmower 100 is in some embodiments arranged with sensors for deduced reckoning 180. The robotic lawnmower 100 may thus continue operating based on the deduced reckoning sensors 180 and in some embodiments the robotic lawnmower 100 is configured to continue operating by performing a planned path utilizing the deduced reckoning sensor In some embodiments the robotic lawnmower 100 is configured to continue operating by returning along a travelled path (referenced TP in figure 3B) utilizing the deduced reckoning sensor, where the path travelled is recorded and then re-travelled. The travelled path may be recorded based on the deduced reckoning sensors 180. Altematively or additionally, the travelled path is recorded based on the satellite navigation sensor 185, which recording is transforrned to control operations based on deduced reckoning sensors, such as wheel turns.In some embodiments the robotic 1aWnmoWer 100 is configured to continue operating by eXecuting an at least semi-random path utilizing the deduced reckoning sensor 180. And, in some such embodiments the robotic 1aWnmoWer 100 is configured to continue operating by eXecuting a zigzag pattern. This allows for potentially finding a location that is outside the shadoWed area quicker.
In order to avoid that the robotic 1aWnmoWer 100 gets stuck outside the Working area and has to be picked up by the user, the robotic 1aWnmoWer may be configured to stay Within a grassy area even if the location is not deterrnined accurately. In some such embodiments the robotic 1aWnmoWer is configured to turn back 460 When the grass sensor (or other ground sensor) 190 indicates 450 that the robotic 1aWnmoWer Will no longer be operating on grass (or other type of permitted ground) if the robotic 1aWnmoWer continues ahead. For example if the robotic 1aWnmoWer 100 is approaching the point referenced A in figure 3B, the robotic 1aWnmoWer may sense that there is no grass (or other type of permitted ground) in front of it and tum back to Where it knows there is grass (or other type of permitted ground). The robotic 1aWnmoWer may turn back by reversing and turning While detecting grass (or other type of permitted ground). Altematively or additionally, the robotic 1aWnmoWer may tum back by reversing and turning While detecting grass (or other type of permitted ground).
Figure 3C also shows a schematic view of a robotic 1aWnmoWer system 200 as in figure 3A or figure 3B. HoWever, in the example situation of figure 3C, the robotic 1aWnmoWer 100 has eXited the shadoWed area and is again able to determine its location and deterrr1ines that it is outside 470 the operational area. The robotic 1aWnmoWer 100 may then return either along 480 the travelled path TP or along 490 a shortest path SP.
In some embodiments, the robotic 1aWnmoWer 100 is thus configured to determine that the navigation sensor is again able to provide an accurate location, and in response thereto determine a current location of the robotic 1aWnmoWer and determine if the current location of the robotic 1aWnmoWer is outside the operational area, and if so return to the operational area.
In some embodiments, the robotic 1aWnmoWer 100 is further configured to return along a travelled path and in some embodiments the robotic 1aWnmoWer is furtherconfigured to determine a shortest path to the operational area and return along the shortest path.
The robotic lawnmower 100 may, in some embodiments where the permitted ground includes grass, not only differentiate between grass or no grass, but to determine between grass that is supposed to be cut, and grass that is assumingly not to be cut. For example, a cut area of grass may be next to a rougher area, and if the rougher area is entered the robotic lawnmower may get stuck. Additionally, the robotic lawnmower may enter a sensitive area that is only to be operated on by special equipment so that tracks are not formed. One such example is a golf course, where the robotic lawnmower is perhaps not delicate enough to operate on the green and not strong enough to operate in the rough.
In some embodiments, the grass sensor is thus further configured to determine the height of the grass and the robotic lawnmower is further configured to determine whether the robotic lawnmower is currently operating on grass or not based on the grass sensor by detern1ining that the robotic lawnmower is currently operating on grass of a height falling within a desired range In some embodiments the desired range corresponds to the height of the grass cut prior to detern1ining that the navigation sensor is unable to provide an accurate location, which enables the robotic lawnmower to continue as long as the robotic lawnmower is cutting grass of a same height as before losing its location.
In some embodiments the desired range is up to 1.5 times the height of the grass cut, which enables for the robotic lawnmower to stay out of areas that are not regularly operated on.
In some embodiments the desired range corresponds to (up to 1.5 times) the height of the work tool 160. In some embodiments the desired range is up to 15 cm. In some embodiments the desired range is up to 10 cm. These embodiments also enables for the robotic lawnmower to stay out of areas that are not regularly operated on.
For the golf-specific examples, in some embodiments the desired range is over 2 mm which enables the robotic lawnmower to stay away from a green.
In some embodiments the desired range is from 4 mm up to 8 mm, which enables the robotic lawnmower to stay on the fairway. Other examples of desired rangeson a golf course includes, but is not limited to a desired range for greens 2.1 mm, a desired range for fore greens 5.7 mm, a desired range for tees 8.9 mm, a desired range for fairWays 8.3 mm, a desired range for semi rough 2.16 cm, a desired range for a second moWing 5.7 cm and a desired range for the roughest or toughest Kentucky blue grass-rough 8.9 cm.
It should also be noted that the desired range may be for a Whole operational area 205 or for specific portions of the operational area The robotic laWnmoWer 100 may, in some embodiments, not only differentiate between grass or not grass, but to determine between grass that is supposed to be cut, and grass that is assumingly not to be cut based on the type of grass. In some embodiments, the grass sensor is thus further configured to determine the type of the grass and the robotic laWnmoWer is further configured to determine Whether the robotic laWnmoWer is currently operating on grass or not based on the grass sensor by deterrnining that the robotic laWnmoWer is currently operating on grass of a desired type. In some embodiments the desired range corresponds to the type of the grass cut prior to deterrnining that the navigation sensor is unable to provide an accurate location, Which enables the robotic laWnmoWer to continue as long as the robotic laWnmoWer is cutting grass of a same type as before losing its location.

Claims (22)

1. A robotic 1aWnmoWer (100) arranged to operate in an operational area, the robotic 1aWnmoWer comprising a Work tool (160), a navigation sensor, a ground sensor (190) and a controller (110), Wherein the signal-based navigation sensor is configured to provide a current location of the robotic 1aWnmoWer (100), Wherein the ground sensor (190) is configured to provide a deterrnination of Whether the robotic 1aWnmoWer is currently operating on perrnitted ground or not, and Wherein the controller is configured to: cause the robotic 1aWnmoWer (100) to operate in the operational area With the Work tool (160) active; detern1ine that the navigation sensor is unable to provide an accurate location; and in response thereto detern1ine Whether the robotic 1aWnmoWer is currently operating on perrnitted ground or not based on the ground sensor (190), and if so, continue operating With the Work tool active, and if not so, continue operating With the Work tool deactivated.
2. The robotic 1aWnmoWer (100) according to claim 1, Wherein the controller is further configured to deterrnine that the robotic 1aWnmoWer is again operating on perrnitted ground, and in response thereto continue operating With the Work tool activated.
3. The robotic 1aWnmoWer (100) according to claim 1 or 2, Wherein the robotic 1aWnmoWer further comprises at least one deduced reckoning sensor and Wherein the controller is further configured to continue operating by performing a planned path utilizing the deduced reckoning SCIISOY.
4. The robotic 1aWnmoWer (100) according to claim 1 or 2, Wherein the robotic 1aWnmoWer further comprises at least one deduced reckoning sensor and Wherein the controller is further configured to continue operating by returning along a travelled path utilizing the deduced reckoning sensor
5. The robotic laWnmoWer (100) according to claim 1 or 2, Wherein the robotic laWnmoWer further comprises at least one deduced reckoning sensor and Wherein the controller is further configured to continue operating by eXecuting an at least semi- random path utilizing the deduced reckoning sensor
6. The robotic laWnmoWer (100) according to claim 5, Wherein the controller is further configured to continue operating by eXecuting a zigzag pattern.
7. The robotic laWnmoWer (100) according to any preceding claim, Wherein the controller is further configured to detern1ine that the navigation sensor is again able to provide an accurate location, and in response thereto detern1ine a current location of the robotic laWnmoWer and detern1ine if the current location of the robotic laWnmoWer is outside the operational area (205), and if so, return to the operational area (205).
8. The robotic laWnmoWer (100) according to claim 7, Wherein the controller is further configured to return along a travelled path.
9. The robotic laWnmoWer (100) according to claim 7, Wherein the controller is further configured to deterrnine a shortest path to the operational area and return along the shortest path.
10. The robotic laWnmoWer (100) according to any preceding claim, Wherein the ground sensor (190) comprises a grass sensor, and Wherein the permitted ground includes grass.
11. The robotic 1aWnmoWer (100) according to claim 10, Wherein the controller is further configured to continue operating based on the grass sensor, Whereby the controller is further configured to tum back When the grass sensor indicates that the robotic 1aWnmoWer Will no longer be operating on pern1itted ground if the robotic 1aWnmoWer continues ahead.
12. The robotic 1aWnmoWer (100) according to claim 10 or 11, Wherein the grass sensor (190) is further configured to detern1ine the height of the grass and, Wherein the controller is further configured to detern1ine Whether the robotic 1aWnmoWer is currently operating on grass or not based on the grass sensor by deterrnining that the robotic 1aWnmoWer is currently operating on grass of a height falling Within a desired range.
13. The robotic 1aWnmoWer (100) according to claim 12, Wherein the desired range corresponds to the height of the grass cut prior to deterrnining that the navigation sensor is unable to provide an accurate location.
14. The robotic 1aWnmoWer (100) according to claim 12, Wherein the desired range is up to 1.5 times the height of the grass cut.
15. The robotic 1aWnmoWer (100) according to claim 12, Wherein the desired range corresponds to the height of the Work tool (160).
16. The robotic 1aWnmoWer (100) according to claim 12, Wherein the desired range is up to 15 cm.
17. The robotic 1aWnmoWer (100) according to claim 12, Wherein the desired range is up to 10 cm.
18. The robotic 1aWnmoWer (100) according to claim 12, Wherein the desired. range is over 2 mm.
19. The robotic 1aWnmoWer (100) according to claim 12, Wherein the desired range is from 4 mm up to 8 mm.
20. The robotic 1aWnmoWer (100) according to any of claims 11 to 19, Wherein the grass sensor is further configured to determine the type of the grass and, Wherein the controller is further configured to determine Whether the robotic 1aWnmoWer is currently operating on grass or not based on the grass sensor by deterrnining that the robotic 1aWnmoWer is currently operating on grass of a type falling Within a desired type.
21. The robotic 1aWnmoWer (100) according to any preceding claim, Wherein the ground sensor (190) comprises a gravel sensor, a sand sensor and/or a paved path sensor, and Wherein the permitted ground includes gravel, sand and/or paved path.
22. A method for use in a robotic 1aWnmoWer (100) arranged to operate in an operational area, the robotic 1aWnmoWer comprising a Work tool (160), a navigation sensor, and a ground sensor (190), Wherein the signal-based navigation sensor is configured to provide a current location of the robotic 1aWnmoWer (100), Wherein the ground sensor (190) is configured to provide a deterrnination of Whether the robotic 1aWnmoWer is currently operating on permitted ground or not, and Wherein the method comprises: causing the robotic 1aWnmoWer (100) to operate in the operational area With the Work tool (160) active; detern1ining that the navigation sensor is unable to provide an accurate location; and in response thereto deterrnining Whether the robotic 1aWnmoWer is currently operating on permitted ground or not based on the ground sensor (190), and if so, continuing operating With the Work tool active, and if not so, continuing operating With the Work tool deactivated.
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