Classifications

• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
  • G05D1/02—Control of position or course in two dimensions
  • G05D1/021—Control of position or course in two dimensions specially adapted to land vehicles
  • G05D1/0268—Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means
  • G05D1/027—Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means comprising intertial navigation means, e.g. azimuth detector
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C22/00—Measuring distance traversed on the ground by vehicles, persons, animals or other moving solid bodies, e.g. using odometers, using pedometers
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01D—HARVESTING; MOWING
  • A01D34/00—Mowers; Mowing apparatus of harvesters
  • A01D34/006—Control or measuring arrangements
  • A01D34/008—Control or measuring arrangements for automated or remotely controlled operation
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
  • G01C21/00—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00
  • G01C21/10—Navigation; Navigational instruments not provided for in groups G01C1/00 - G01C19/00 by using measurements of speed or acceleration
  • G01C21/12—Navigation; 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
  • G01C21/16—Navigation; 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
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
  • G05D1/02—Control of position or course in two dimensions
  • G05D1/021—Control of position or course in two dimensions specially adapted to land vehicles
  • G05D1/0268—Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means
  • G05D1/0274—Control of position or course in two dimensions specially adapted to land vehicles using internal positioning means using mapping information stored in a memory device
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
  • G05D1/02—Control of position or course in two dimensions
  • G05D1/021—Control of position or course in two dimensions specially adapted to land vehicles
  • G05D1/0276—Control of position or course in two dimensions specially adapted to land vehicles using signals provided by a source external to the vehicle
  • G05D1/0278—Control 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
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
  • G05D1/20—Control system inputs
  • G05D1/24—Arrangements for determining position or orientation
  • G05D1/247—Arrangements for determining position or orientation using signals provided by artificial sources external to the vehicle, e.g. navigation beacons
  • G05D1/248—Arrangements 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
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D2111/00—Details of signals used for control of position, course, altitude or attitude of land, water, air or space vehicles
  • G05D2111/50—Internal signals, i.e. from sensors located in the vehicle, e.g. from compasses or angular sensors
  • G05D2111/52—Internal 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
• • G—PHYSICS
  • G05—CONTROLLING; REGULATING
  • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
  • G05D2111/00—Details of signals used for control of position, course, altitude or attitude of land, water, air or space vehicles
  • G05D2111/50—Internal signals, i.e. from sensors located in the vehicle, e.g. from compasses or angular sensors
  • G05D2111/54—Internal 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

Definitions

• 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.
• 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.
• 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.
• 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
• the signal-based navigation sensor is configured to provide a current location of the robotic lawnmower
• the ground sensor is configured to provide a determination of whether the robotic lawnmower is currently operating on permitted ground or not
• 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.
• 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.
• 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 turn back when the grass sensor indicates that the robotic lawnmower will no longer be operating on permitted ground if the robotic lawnmower continues ahead.
• 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.
• controller is further configured to return along a travelled path.
• controller is further configured to determine a shortest path to the operational area and return along the shortest path.
• the ground sensor comprises a grass sensor, and wherein the permitted ground includes grass.
• 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 determining that the robotic lawnmower is currently operating on grass of a height falling within a desired range.
• the desired range corresponds to the height of the grass cut prior to determining that the navigation sensor is unable to provide an accurate location.
• the desired range is up to 1.5 times the height of the grass cut.
• the desired range corresponds to the height of the work tool.
• 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.
• 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 determining that the robotic lawnmower is currently operating on grass of a type falling within a desired type.
• 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.
• the robotic lawnmower comprising a work tool, a navigation sensor, and a ground sensor
• the signal-based navigation sensor is configured to provide a current location of the robotic lawnmower
• the ground sensor is configured to provide a determination of whether the robotic lawnmower is currently operating on permitted ground or not
• 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; determining 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.
• Figure 1 A shows an example of a robotic lawnmower according to some embodiments of the teachings herein;
• Figure IB 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 3 A 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.
• Figure 4 shows a corresponding flowchart for a method according to some example embodiments of the teachings herein.
• FIG 1A shows a perspective view of a robotic lawnmower 100.
• the example of figure 1 A (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 monochassis type (as in figure 1 A).
• 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.
• 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.
• 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 predetermined).
• Figure IB shows a schematic overview of the robotic lawnmower 100.
• 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.
• 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.
• 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.
• 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) 150.
• 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 1 A,
• the controller 110 may be implemented using any suitable, available processor or Programmable Logic Circuit (PLC).
• PLC Programmable Logic Circuit
• 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.
• wireless communication devices such as 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 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.
• 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.
• the work tool is the watering arrangement
• 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.
• 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.
• GPS Global Positioning System
• GNSS Global Navigation Satellite System
• the magnetic sensors 170 as will be discussed below are optional.
• 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.
• 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.
• 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).
• 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 transmitted 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.
• 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.
• the map application includes one or more start regions and one or more goal regions for each work area.
• the map application also includes one or more transport areas.
• the map application is in some embodiments stored in the memory 120 of the robotic working tool(s) 100.
• the map application is stored in the server (referenced 240 in figure 2).
• maps are stored both in the memory 120 of the robotic working tool(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 determination of what type of ground the area currently being operated on is of.
• 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.
• 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.
• 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.
• the grass sensor is further configured to determine the height of the grass being cut, based on image processing.
• the grass sensors 190 comprises a capacitive sensor that based on the capacitance under the robotic lawnmower determines whether there is grass or not.
• 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.
• the ground sensors 190 comprises gravel sensors for enabling a determination of whether the area currently being operated on is of gravel.
• the ground sensors 190 comprises sand sensors for enabling a determination of whether the area currently being operated on is of sand.
• the ground sensors 190 comprises paved path sensors for enabling a determination of whether the area currently being operated on is a paved path.
• 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 determination of whether the ground is of a permitted type or not.
• FIG. 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.
• 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 100.
• 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.
• the robotic lawnmower(s) is exemplified by a robotic lawnmower, whereby the robotic lawnmower system may be a robotic lawnmower 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 robotic lawnmower system may be a robotic lawnmower 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 205 A and a second work area 205B connected by a transport area TA.
• 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.
• corridors also referred to as corridors.
• 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.
• the garden may contain a number of obstacles, for example a number of trees, stones, slopes and houses or other structures.
• 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 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 lawnmower 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 205 exemplified with referenced to figure 2 may thus be such a non-uniform work area as disclosed in this paragraph that the robotic lawnmower is arranged to traverse and/or operate in.
• 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 alternatively 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 100, direct from a user equipment 250, indirect from the robotic working tool 100 via the service station 210, and/or indirect from the robotic working tool 100 via the user equipment 250.
• 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.
• Figure 3 A shows a simplified view of a robotic lawnmower system 200 in an operational area 205 as in figure 2.
• Figure 3 A shows how a robotic lawnmower 100 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.
• 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.
• a gravel path GP is also shown in figure 3 A. As with the grass, the gravel path GP extends outside the boundary 220.
• 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.
• the controller possibly through the satellite navigation sensor may be configured to determine that the location is not accurate if the accuracy falls below a threshold value.
• 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.
• 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.
• FIG. 4 shows a flowchart for a general method according to herein. The method is for use in a robotic lawnmower as in figures 1 A and IB.
• 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.
• the robotic lawnmower determines 420 that the navigation sensor 185 is unable to provide an accurate location.
• 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.
• the robotic lawnmower 100 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 determine 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.
• the permitted ground includes grass.
• the determination whether the ground is permitted is a determination 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.
• 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 100.
• FIG. 3B also shows a schematic view of a robotic lawnmower system 200 as in figure 3 A. 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.
• 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 180.
• 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.
• the travelled path is recorded based on the satellite navigation sensor 185, which recording is transformed to control operations based on deduced reckoning sensors, such as wheel turns.
• the robotic lawnmower 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 lawnmower 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.
• the robotic lawnmower may be configured to stay within a grassy area even if the location is not determined accurately.
• the robotic lawnmower is configured to turn back 460 when the grass sensor (or other ground sensor) 190 indicates 450 that the robotic lawnmower will no longer be operating on grass (or other type of permitted ground) if the robotic lawnmower continues ahead.
• the robotic lawnmower may sense that there is no grass (or other type of permitted ground) in front of it and turn back to where it knows there is grass (or other type of permitted ground).
• the robotic lawnmower may turn back by reversing and turning while detecting grass (or other type of permitted ground).
• the robotic lawnmower may turn back by reversing and turning while detecting grass (or other type of permitted ground).
• Figure 3C also shows a schematic view of a robotic lawnmower system 200 as in figure 3A or figure 3B.
• the robotic lawnmower 100 has exited the shadowed area and is again able to determine its location and determines that it is outside 470 the operational area.
• the robotic lawnmower 100 may then return either along 480 the travelled path TP or along 490 a shortest path SP.
• the robotic lawnmower 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 lawnmower and determine if the current location of the robotic lawnmower is outside the operational area, and if so return to the operational area.
• the robotic lawnmower 100 is further configured to return along a travelled path and in some embodiments the robotic lawnmower is further configured 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.
• 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 determining that the robotic lawnmower is currently operating on grass of a height falling within a desired range
• the desired range corresponds to the height of the grass cut prior to determining 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.
• 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.
• 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.
• the desired range is over 2 mm which enables the robotic lawnmower to stay away from a green.
• 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 ranges on 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.
• the desired range may be for a whole operational area 205 or for specific portions of the operational area 205.
• 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.
• 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 determining that the robotic lawnmower is currently operating on grass of a desired type.
• the desired range corresponds to the type of the grass cut prior to determining 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.

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• 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)

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• 2022
  • 2022-03-02 SE SE2250281A patent/SE546086C2/en unknown
  • 2022-12-18 EP EP22838998.7A patent/EP4487191A1/de active Pending
  • 2022-12-18 WO PCT/SE2022/051199 patent/WO2023167617A1/en not_active Ceased

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