Improved robotic work tool

TECHNICAL FIELD

0001This application relates to a method and a robotic work tool system for enabling user control of a robotic work tool.

BACKGROUND

0002Robotic garden tools such as robotic lawn mowers are arranged to autonomously travel within a working area and to perform a task, such as mowing the lawn, within the working area. A docking device may be arranged within or in the proximity of a border of the working area.

0003A robotic garden tool, travelling within the working area may be arranged to return to the docking device as a result of various reasons. As an example, a battery powered robotic garden tool may be configured to autonomously return to a docking device comprising a battery charging unit as soon as the charging level of the battery falls below a threshold value.

0004Robotic garden tools may also be equipped with a user actuated input device, which upon activation prompts the robotic garden tool to return to the docking device. In that way, an operator may search out the robotic garden tool travelling within the working area and then manually trigger the robotic garden tool to return to the docking device by means of activating the user actuated input device.

0005A remote control may also be used to manually trigger the robotic garden tool to return to the docking device. Furthermore, remote controls have a tendency to be lost or misplaced and especially if more than one user handles the remote control.

0006However, there is a need for a simple and robust arrangement for allowing an operator to manually trigger the robotic garden tool to return to the docking device.

SUMMARY

0007According to the invention, the problems above are solved by means of providing a robotic garden tool guiding system in which the docking device comprises a return command input device. In that way the operator does not need to search out the robotic garden tool before triggering it to return to the docking device. Furthermore, the return command input device is always easy to find, since it is permanently arranged on the docking device. The arrangement may be manufactured at a low cost.

0008It is an object of the teachings of this application to overcome the problems listed above by providing a robotic work tool system, comprising a robotic work tool, a charging station, a boundary wire, a signal generator for generating and transmitting a signal through said boundary wire for demarcating a work area, said robotic work tool system being configured to receive user input indicating a functionality through a user control console, and transmit a message to the robotic work tool, wherein the message comprises a command for effecting the indicated functionality; whereby the robotic work tool is configured to receive said message and execute the indicated functionality.

0009It is an object of the teachings of this application to overcome the problems listed above by providing a method for use in a robotic work tool system, comprising a robotic work tool, a charging station, a boundary wire, a signal generator for generating and transmitting a signal through said boundary wire for demarcating a work area, said method comprising receiving user input indicating a functionality through a user control console, and transmitting a message to the robotic work tool, wherein the message comprises a command for effecting the indicated functionality; and receiving said message and executing the indicated functionality in the robotic work tool.

0010In one embodiment the robotic work tool is a robotic lawnmower.

0011The inventors of the present invention have realized, after inventive and insightful reasoning, that by enabling for a simplified user interface arranged on or adjacent to the charging station a user is enabled to control the robotic work tool in a simple and intuitive manner and in a timely fashion.

0012The teachings herein find use in robotic work tool systems such as robotic lawnmower systems. 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.

0013Generally, 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 DRAWINGS

0014The invention will be described in further detail under reference to the accompanying drawings in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figure 1</figref> shows a schematic overview of a robotic garden tool system according to one embodiment of the teachings of this application;</li><li><figref idref="f0001">Figure 2</figref> shows a schematic view of a robotic garden tool and a docking station according to one embodiment of the teachings of this application;</li><li><figref idref="f0002">Figure 3</figref> shows a schematic overview of a robotic work tool according to one embodiment of the teachings of this application;</li><li><figref idref="f0003">Figures 4A and 4B</figref> each shows a schematic view of a robotic working tool system according to one embodiment of the teachings of this application; and</li><li><figref idref="f0002">Figure 5</figref> shows a flowchart for a method according to one embodiment of the teachings of this application.</li></ul>

DETAILED DESCRIPTION

0015The 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; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

0016<figref idref="f0001">Figure 1</figref> shows a robotic garden tool system. The robotic garden tool guiding system 100 comprises a docking device 110. The docking device has a signal transferring unit 111. The robotic garden tool guiding system also comprises a robotic garden tool 120 having an operating state in which it travels within a working area, and a charging state in which it is connected to the docking device 110. The robotic garden tool has a signal sensing unit 121 and a control unit 122. The control unit 122 is arranged to initiate movement of the robotic garden tool from the operating state to the charging state, as a response to a predetermined recall command received by the signal sensing unit 121. The robotic garden tool guiding system also comprises a communication interface 130 interconnecting the signal transferring unit 111 of the docking device 110 and the signal sensing unit 121 of the robotic garden tool 120.

0017The docking device 110 comprises a user actuated input member 112, which user actuated input member 112 is operable to trigger transfer of the predetermined recall command from the signal transferring unit 111 to the signal sensing unit 121, via the communication interface 130 as can be seen in <figref idref="f0001">figure 2</figref>.

0018The communication interface may comprise a boundary wire 131. Alternatively, the communication interface may comprise a radio link.

0019<figref idref="f0002">Figure 3</figref> shows a schematic overview of a robotic work tool 300 having a body 340 and a plurality of wheels 330. In the exemplary embodiment of <figref idref="f0002">figure 3</figref> the robot 300 has 4 wheels 330, two front wheels 330' and the rear wheels 330". At least some of the wheels 330 are driveably connected to at least one electric motor 350. It should be noted that even if the description herein is focussed on electric motors, combustion engines may alternatively be used possibly in combination with an electric motor.

0020In the example of <figref idref="f0002">figure 3</figref>, the rear wheels 330" are connected to each an electric motor 350. This allows for driving the rear wheels 330" independently of one another which, for example, enables steep turning.

0021The robotic work tool 300 also comprises a controller 310. The controller 310 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 a computer readable storage medium (disk, memory etc) 320 to be executed by such a processor. The controller 310 is configured to read instructions from the memory 320 and execute these instructions to control the operation of the robotic work tool 300. The controller 310 may be implemented using any suitable, publically available processor or Programmable Logic Circuit (PLC). The memory 320 may be implemented using any commonly known technology for computer-readable memories such as ROM, RAM, SRAM, DRAM, CMOS, FLASH, DDR, SDRAM or some other memory technology.

0022The robot 300 further has at least one sensor 370, in the example of <figref idref="f0002">figure 3</figref> there are two sensors 370, arranged to detect a magnetic field (not shown). The sensors are connected to the controller 310 and the controller 310 is configured to process any signals received from the sensors 370. The sensor signals may be caused by the magnetic field caused by a control signal being transmitted through a boundary wire (for more details on charging stations, control signals and boundary wires, see the description below with reference to <figref idref="f0001">figure 2</figref>). This enables the controller 310 to determine whether the robot 300 is inside or outside an area enclosed by a boundary wire.

0023The controller 310 is connected to the motors 350 for controlling the propulsion of the robot 300 which enables the robot 300 to service an enclosed area without leaving the area.

0024The robot 300 also comprises a work tool 360, which may be a grass cutting device, such as a rotating blade 360 driven by a cutter motor 365. The cutter motor 365 is connected to the controller 310 which enables the controller 310 to control the operation of the cutter motor 365. The controller is also configured to determine the load exerted on the rotating blade, by for example measure the power delivered to the cutter motor 365 or by measuring the axle torque exerted by the rotating blade. The robot 300 is, in one embodiment, a lawnmower robot.

0025The robot 300 also has (at least) one battery 380 for providing power to the motors 350 and the cutter motor 365.

0026<figref idref="f0003">Figure 4A</figref> shows a schematic view of a robotic working tool system 400 comprising a charging station 410 and a boundary wire 450 arranged to enclose a working area 405, the working area 405 not necessarily being a part of the robot system 400, in which the robotic work tool 300 is supposed to service. The charging station 410 has a charger 420 coupled to, in this embodiment, two charging plates 430. The charging plates 430 are arranged to co-operate with corresponding charging plates (not shown) of the robotic work tool 300 for charging the battery 380 of the robotic work tool 300. The charging station 410 also has, or may be coupled to, a signal generator 440 for providing a control signal (not shown) to be transmitted through the boundary wire 450. The control signal preferably comprises a number of periodic current pulses. As is known in the art, the current pulses will generate a magnetic field around the boundary wire 450 which the sensors 370 of the robotic work tool 300 will detect. As the robotic work tool 300 (or more accurately, the sensor 370) crosses the boundary wire 450 the direction of the magnetic field will change. The robotic work tool 300 will thus be able to determine that the boundary wire has been crossed. The use of more than one sensor 370 enables the controller 310 of the robotic work tool 300 to determine how the robotic work tool 300 is aligned with relation to the boundary wire 450 by comparing the sensor signals received from each sensor 170. This enables the robot to follow the boundary wire 450, for example when returning to the charging station 410 for charging.

0027Optionally, the charging station 410 also has a guide cable 460 for enabling the robot to find the entrance of the charging station 410. In one embodiment the guide cable 460 is formed by a loop of the boundary wire 450.

0028In one embodiment the guide wire 460 is used to generate a magnetic field 465 for enabling the robotic work tool 300 to find the charging station without following a guide cable 460. The field is sometimes referred to as an F-range indicating the range within which the field can be sensed. The F-range 465 may be generated by the guide cable 460 or other cable, possibly being arranged in a loop, or other means for generating a magnetic field.

0029The robotic work tool 300 may then find the charging station 410 by following the F-range 465 towards increasing field strength. By sending different current pulses through the guide cable 460 and the boundary wire 450, and possibly by generating the magnetic field in the F-range using a different current profile, the robotic work tool 300 will be able to determine which magnetic field results from which cable/field. The different control signals may for example comprise coded signals that differentiate the cables 450, 460.

0030The charging station 410 is also arranged with a communication interface 480. In one embodiment the communication interface is operably connected to (or part of) the signal generator 440 for transmitting a coded signal through the boundary wire, and/or the guide cable 460.

0031In one embodiment the communication interface is a wireless communication interface such as a radio frequency interface, for example configured to operate according to the LTE standard (Long Term Evolution).

0032The charging station 410 is further arranged with a user control console 470. In one embodiment the user control console comprises a button 470. In one embodiment the user control console is arranged to be positioned remotely from the charging station 410. This allows for mounting the user control console 470 in a convenient place.

0033The use of a few or a single button enables for easy access to a user, and for indicating the function of the button. For example the function of a stop button is easily indicated by a red button signalling intuitively to any user or by passer the function without the need for consulting a manual or other instructions.

0034The charging station 410 is configured to send out a signal to the robotic work tool 300, in response to an actuation of the button 470, wherein the signal comprises a command for effectuating the functionality associated with the button 470.

0035In one embodiment the user control console comprises a button 470 (for example red) associated with a stop functionality, whereby the robotic work tool 300 is caused to stop its current operation upon activation of the stop button 470. In one such embodiment the robotic work tool 300 is configured to move to a boundary wire (possibly discontinue its mowing operation while moving) before stopping completely to avoid that the user has to go out and move the robotic work tool by hand for example if it is in the way.

0036In one embodiment the user control console comprises a button 470 (for example black) associated with a recall functionality, whereby the robotic work tool 300 is caused to stop its current operation and return to the charging station upon activation of the recall button 470. In one embodiment the robotic work tool 300 is configured to continue the mowing operation when searching for and returning to the charging station 410 for enabling a more time efficient operation. In one embodiment the robotic work tool 300 is configured to discontinue the mowing operation when searching for and returning to the charging station 410 for enabling a safer operation in case the robotic work tool 300 is being recalled for security reasons such as when allowing pets or children to play in the work area 405.

0037In one embodiment the user control console comprises a button 470 (for example orange) associated with a pause functionality, whereby the robotic work tool 300 is caused to pause its current operation upon activation of the pause button 470. In one such embodiment the robotic work tool 300 is configured to move to a boundary wire (possibly discontinue its mowing operation while moving) before pausing. In one embodiment the pause functionality is associated with a time period and the robotic work tool 300 and/or the charging station 410 is arranged to monitor the time period and upon expiration of the time period restart the robotic work tools 300 operation.

0038In one embodiment the user control console comprises a button 470 (for example green) associated with a start functionality, whereby the robotic work tool 300 is caused to start or restart its (previous) operation upon activation of the start button 470.

0039In one embodiment the charging station 410 is arranged and configured to service more than one robotic work tool 300, such as a fist robotic work tool 300A and a second robotic work tool 300B.

0040<figref idref="f0003">Figure 4B</figref> shows an example of such a system where a first robotic work tool 300A and a second robotic work tool 300B is arranged to work in a work area 405. In one example, as shown in <figref idref="f0003">figure 4B</figref>, the work area 405 is divided into a first subsection 405A and a second subsection 405B, the first subsection 405A being closer to the charging station 410.

0041In one such embodiment the user control console 470 may comprise a set of function buttons for each robotic work tool 300. In another such embodiment the user control console may comprise one set of buttons and a robotic work tool selection button. In such an embodiment the user may select a robotic work tool 300 for which the function should be effected by pressing the robotic work tool selection button prior to (or after) pressing a functionality button. In one embodiment the charging station 410 is configured to receive a number of selections of robotic work tools 300, by receiving actuations of respective robotic work tool selection buttons, and the charging station 410 signals the functionality to all selected robotic work tools 300. In one embodiment the robotic work tool(s) 300 is/are selected through selections from a robotic work tool list being displayed on a display (not shown) comprised in the user control console 470, for example an LCD (Liquid Cristal Display).

0042By configuring the charging station 410 to receive the robotic work tool selection before the functionality to be effected, a user is sure that the functionality is signaled to all or the selected robotic work tools 300 upon pressing the corresponding functionality button. This ensures a fast reaction from the system in a situation requiring haste (such as in an emergency) where the charging station 410 does not hold off on waiting for further instructions as a functionality button 470 is pressed or actuated.

0043If no robotic work tool selection button 470 is pressed, or not robotic work tool is selected in an n other fashion, the functionality is signaled to all robotic work tools 300 serviced by the charging station 410. This allows for a reduced set of buttons which enables control of a selected robotic work tool 300 and for simple and fast control of a group of robotic work tools 300.

0044In an embodiment where the charging station 410 services more than one robotic work tool 300, as in <figref idref="f0003">figure 4B</figref>, the charging station 410 is configured to identify an robotic work tool 300. The identification can be implemented as the robotic work tool 300 actively identifying itself by providing an identification signal, for example through the charging plates 430 or through a wireless interface. In one embodiment the robotic work tool 300 may communicate with the charging station by causing the driving wheels 330" to deliver a vibration or knocking pattern that is sensed by the charging station.

0045As stated above <figref idref="f0003">figure 4B</figref> shows such a robotic work tool system 400 where a first robotic work tool 300A and a second robotic work tool 300B are operating and being serviced by the same charging station 410.

0046The charging station 410 is thus arranged to know the identity of a first robotic work tool 300A currently occupying the charging station 410. To avoid that a second robotic work tool 300B tries to dock with the charging station as it tries to return to the charging station at the end of its work session or because it is running low on power, and also to prevent that such second robotic work tool 300B is blocking the first robotic work tool 300A currently being serviced from reversing out of the charging station 410, the charging station 410 is configured to signal to the second robotic work tool 300B that the charging station 410 is occupied and that the second robotic work tool 300B should pause any attempt to reach the charging station 410.

0047To avoid that the second robotic work tool 300B runs out of power while pausing, the robotic work tool 300B is configured to communicate its battery status to the charging station 410. If the charging station 410 receives an indication that the second robotic work tool 300B is running out of power it may instruct the robotic work tool 300A currently occupying the charging station 410 to exit the charging station 410. Dependent on the reason of the robotic work tool 300A occupying the charging station 410 (for example an active recall or to recharge) the charging station 410 can instruct the robotic work tool 300A to exit the charging station 410 and to park adjacent the charging station 410 or the boundary wire 250, to continue its work operation or to exit the charging station 410 and reconnect to the charging station 410 as the second robotic work tool 300B has been serviced.

0048The work area 405 of <figref idref="f0003">figure 4B</figref> is divided into a first subsection 405A and a second subsection 405B. The first and second robotic work tool 300A, 300B may be arranged to service each a subsection 405A,B.

0049In one embodiment, the charging station 410 may also be arranged to instruct the second robotic work tool 300B to service the work area subsection 405A of the first robotic work tool 300A as the first robotic work tool 300A is being serviced by the charging station 410 - or otherwise prevented from servicing its work area subsection 405A - in addition to servicing its own work area subsection 405B or instead of servicing its own work area subsection 405B.

0050The charging station 410 may also be arranged to instruct the first robotic work tool 300A to service the second work area subsection 405B as the first robotic work tool 300A has been serviced by the charging station 410.

0051This allows for arranging the first robotic work tool 300A and the second robotic work tool 300B to service a work area subsection 405A, 405B in accordance with is battery status. The most freshly charged robotic work tool 300 is instructed to service or operate in the most remote work area 405B. This allows for running the robotic work tools for a longer time as the robotic work tool 300 about to run out of power the soonest is always the robotic work tool 300 closest to the charging station 410.

0052In one embodiment the user control console comprises a button 470 (for example blue or carrying a double arrow or two counter facing arrows) associated with a switch functionality, whereby the robotic work tool 300 is caused to switch from one work area subsection 405A to another work area subsection 405B upon activation of the switch button 470. This enables for a user to control which robotic work tool 300 is operating in which subsection and also how many robotic work tools 300 are operating in each subsection 405A,B. This is useful if, for example a pet is playing in a first subsection 405A, whereby the second work area subsection 405B may be more efficiently serviced by two robotic work tools 300a and 300B instead of one robotic work tool 300A idly waiting.

0053It should be noted that the manner of arranging the work area into subsections and operating in the subsection(s) furthest away from the charging station when the battery is fully loaded may also be used for a robotic work tool system comprising only one robot as well. In such an embodiment the robotic work tool is configured to determine if the current battery level is above a threshold associated with a subsection and when the current level falls below the threshold level, the robotic work tool switches to a subsection having a lower threshold level. This enables the robotic work tool to use more of its battery capacity while still being able to return to the charging station as it progressively moves closer and closer to the charging station as its battery level goes down.

0054It should be noted that although the description herein refers to buttons, it should be noted that other switches are also plausible.

0055<figref idref="f0002">Figure 5</figref> shows a flow chart for a general method of the teachings herein. The method will be described with simultaneous reference to <figref idref="f0001">figures 1, 2</figref>, <figref idref="f0002">3</figref> and <figref idref="f0003">4</figref>.

0056The method is implemented by a robotic work tool 300, such as the robotic work tool 300 of <figref idref="f0002">figure 3</figref> being part of a robotic work tool system, such as the robotic work tool system 400 of <figref idref="f0003">figure 4</figref>. The robotic work tool system receives 510 user input indicating a functionality through a user control console 470, and transmits 530 a message to the robotic work tool 300, wherein the message comprises a command for effecting the indicated functionality, and receiving said message and executing 540 the indicated functionality in the robotic work tool 300. Optionally, the robotic work tool system receives 520 a selection of which robotic work tool to transmit the message to.

0057References to 'computer-readable storage medium', 'computer program product', 'tangibly embodied computer program' etc. or a 'controller', 'computer', 'processor' etc. should be understood to encompass not only computers having different architectures such as single/multi- processor architectures and sequential/parallel architectures but also specialized circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processing devices and other devices. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc.

0058One benefit of the teachings herein is that the robotic work tool system is enabled to adapt to differing work areas so that the risk that the robotic work tool is unable to reach the charging station is greatly reduced.

0059The invention has mainly been described above with reference to a few embodiments. However, as is readily appreciated by a person skilled in the art, other embodiments than the ones disclosed above are equally possible within the scope of the invention, as defined by the appended patent claims.