SE545728C2

SE545728C2 - Method of providing a position estimate of a robotic tool, a robotic tool, and a robotic tool system

Info

Publication number: SE545728C2
Application number: SE2050629A
Authority: SE
Inventors: Anders Hjalmarsson; Kent Askenmalm
Original assignee: Husqvarna Ab
Priority date: 2020-06-02
Filing date: 2020-06-02
Publication date: 2023-12-19
Also published as: SE2050629A1; WO2021244883A1; DE112021002716T5

Abstract

A method (100) of providing a current position estimate of a first robotic tool (r1) of a robotic tool system (1) is disclosed. The robotic tool system (1) comprises the first robotic tool (r1) and one or more second robotic tools (r2, r2’, r2”). The method (100) comprises the steps of outputting (110) a beacon signal/signals (Bs) from the one or more second robotic tools (r2, r2’, r2”), receiving (130) the beacon signal/signals (Bs) at the first robotic tool (r1), and providing (150) a current position estimate of the first robotic tool (r1) based on the received beacon signal/signals (Bs). The present disclosure further relates to a robotic tool (r1, r2, r2’, r2”) and a robotic tool system (1) comprising two or more robotic tools (r1, r2, r2’, r2”).

Description

Method of providing a position estimate of a Robotic Tool, a Robotic Tool, and a Robotic Tool System TECHNICAL FIELD The present disclosure relates to a method of providing a current position estimate of a robotic tool of a robotic tool system. The present disclosure further relates to a robotic tool and a robotic tool system.

BACKGROUND Self-propelled robotic tools, such as self-propelled autonomous robotic lawnmowers, have become increasingly popular, partly because they usually are capable of performing work which previously was made manually. A self-propelled robotic tool is capable of navigating in an area in an autonomous manner, i.e. without the intervention of a user. The robotic tool may move in a systematic and/or random pattern to ensure that the area is completely covered. Examples of robotic tools include robotic lawnmowers, robotic golf ball collecting tools, robotic vacuum cleaners, robotic ﬂoor cleaners, robotic snow removal tools, robotic mine clearance robots, and the like.

Some robotic tools require a user to set up a border wire around an area that deﬁnes the area to be operated by the robotic tool. Such robotic tools use a sensor to locate the wire and thereby the boundary of the area to be operated. When such a robotic tool reaches the border wire, the robotic tool is usually stopped and then operated in a direction opposite to the direction of travel that the robotic tool had at the time of the detection of the boundary wire.

As an alternative, or in addition, robotic tools may comprise other types of positioning units, such as satellite-based positioning units utilizing a space based satellite navigation system, such as a Global Positioning System (GPS), The Russian GLObal NAvigation Satellite System (GLONASS), European Union Galileo positioning system, Chinese Compass navigation system, or Indian Regional Navigational Satellite System. Satellite-based positioning units provide many advantages. As an example, satellite-based positioning units are passive and does not require transmission of data and operates independently of any telephonic or internet reception. However, satellite-based positioning units are also associated with some drawbacks. One drawback is that the signals from the space based satellite navigation system are relative weak, and obstacles, such as mountains, buildings, trees, and the like, risks blocking the signals from the space based satellite navigation system. lf so, the satellite-based positioning unit may be unable to provide accurate positioning data which may hinder further navigation of a robotic tool in an accurate manner.

As a further alternative, robotic tools may be operated using one or more external beacon markers, such as ultrasonic beacon markers, wherein the robotic tool is provided with a beacon sensor configured to receive a beacon signal sent by the external beacon marker. Thereby, a control arrangement of the robotic tool is able to determine a proximity to one or more external beacon markers so as to provide a position estimate of the robotic tool. External beacon markers have the advantage of not being dependent on sufficiently strong signals from a space based satellite navigation system. However, they are also associated with some problems and drawbacks. For example, they add cost and complexity to a robotic tool system. Moreover, they require a user to position the beacon markers in an area operated by the robotic tool system. Furthermore, the beacon markers are susceptible to potential theft and damage, especially when operating some public areas, such as parks, lawns around commercial buildings, golf clubs, and the like. ln addition, generally, on today's consumer market, it is an advantage if products comprise different features and functions while the products have conditions and/or characteristics suitable for being manufactured and assembled in a cost-efficient manner.

SUMMARY lt is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a ﬁrst aspect of the invention, the object is achieved by a method of providing a current position estimate of a first robotic tool of a robotic tool system, wherein the robotic tool system comprises the ﬁrst robotic tool and one or more second robotic tools, and wherein the method comprises the steps of: l/ . __” Fm» ._ _ u. ~ ~.}\::i}\::x::\-š à Lu, äïíšiëàïrlëšššë ”i Thereby, a method is provided capable of providing a current position estimate of the first robotic tool in a manner independent of the strength of signals from a space based satellite navigation system to the first robotic tool and in a manner circumventing the need for positioning fixed beacon markers in an area to be operated.

As a further result thereof, a method is provided having conditions for facilitating accurate navigation of the ﬁrst robotic tool also in situations in which the ﬁrst robotic tool is in an area having weak signals from a space based satellite navigation system.

Furthermore, since the method circumvents the need for positioning ﬁxed beacon markers in an area to be operated, the method provides conditions for saving cost and complexity of a robotic tool system while providing conditions for facilitating accurate navigation of a robotic tool also in situations in which the robotic tool is in an area having weak signals from a space based satellite navigation system.

Accordingly, a method is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Formatted: Don't add space between paragraphs of the same style, Bulleted + Level: 1 + Aligned at: 0,c cm + Indent at: 1,27 cm < ' Formatted: Font: (Default) Arial *' ******** Formatted: Indent: Left: O cm, First line: O cm Optionally, the method comprises the steps of: - obtaining a relative distance/distances between the first robotic tool and the one or more second robotic tools based on the beacon signal/signals, and - providing the current position estimate of the first robotic tool based on the obtained relative distance/distances.

Thereby, more accurate and reliable current position estimates of the first robotic tool can be provided in an efficient manner.

Optionally, the method comprises the steps of: - estimating an angle/angles of arrival of the beacon signal/signals at the first robotic tool, and - providing the current position estimate of the first robotic tool based on the estimated angle/angles.

Thereby, more accurate and reliable current position estimates of the first robotic tool can be provided in an efficient manner. Furthermore, conditions are provided for obtaining accurate current position estimates of the first robotic tool also in cases of a low number of second robotic tools.

Optionally, the method comprises the steps of: - providing current position data of the one or more second robotic tools, and - providing the current position estimate of the first robotic tool based on the current position data of the one or more second robotic tools.

Thereby, even more accurate and reliable current position estimates of the ﬁrst robotic tool can be provided in an efﬁcient manner. This because the current position data of the one or more second robotic tools is utilized for providing the current position estimate of the ﬁrst robotic tool.

Optionally, the method comprises the steps of: - outputting the current position data from the one or more second robotic tools, and - receiving the current position data at the first robotic tool.

Thereby, the need for an external system or arrangement for outputting the current position data to the first robotic tool is circumvented.

Optionally, the method comprises the steps of: - providing current position data of the first robotic tool, - determining a positioning accuracy of the current position data of the first robotic tool, and - outputting a beacon request signal if the positioning accuracy of the current position data is below a threshold accuracy.

Thereby, a method is provided in which a beacon request signal is outputted if the positioning accuracy of the ﬁrst robotic tool is low. Accordingly, a method is provided in which the first robotic tool can request beacon signals to be sent from one or more second robotic tools in case the positioning accuracy of the ﬁrst robotic tool is low. Thereby, a situation- based method is provided capable of reducing the radio signal use and the energy consumption of a robotic tool system. _ ÄÜIÉ. "ZÄÉ ' ' T. " ._ “_ ff 'L 'I f. f" f f' 'i Optionally, the step of adapting the navigation of the one or more second robotic tools comprises at least one of: - stopping at least one of the one or more second robotic tools, - navigating at least one of the one or more second robotic tools to an area, and - restricting navigation of at least one of the one or more second robotic tools to an area.

Thereby, a more efficient, reliable, and accurate method is provided for providing current position estimates of the first robotic tool. This because the navigation of the one or more second robotic tools is adapted in a manner which may increase the positioning capability of the first robotic tool based on the received beacon signal/signals from the one or more second robotic tools.

Optionally, the robotic tool system comprises two or more second robotic tools, and wherein the step of adapting the navigation of the two or more second robotic tools comprises: - navigating at least one of the two or more second robotic tools to obtain an angle exceeding a threshold angle between two of the two or more second robotic tools measured at the position of the first robotic tool.

Thereby, a more efficient, reliable, and accurate method is provided for providing current position estimates of the first robotic tool. This because the angle between two of the two or more second robotic tools measured at the position of the first robotic tool can provide an accurate positioning of the ﬁrst robotic tool.

Optionally, the method further comprises the steps of: - providing current position data of the first robotic tool, - determining a positioning accuracy of the current position data of the first robotic tool, - determining an estimate accuracy of the current position estimate, and - restricting operation of the ﬁrst robotic tool if the positioning accuracy is below a threshold accuracy and if the estimate accuracy is below a threshold accuracy.

Thereby, a method is provided having conditions for improving safety and reliability of a robotic tool system. This because operation of the first robotic tool is restricted if being unable to provide an accurate positioning of the ﬁrst robotic tool.

Q »w .-\~\'.- ~~ -~.-\«\»\.-\~»\ Optionally, the method comprises the steps of: - providing current position data of the first robotic tool, - determining a positioning accuracy of the current position data of the first robotic tool, - providing accuracy map data indicative of the positioning accuracy in areas operated by the robotic tool system.

Thereby, a method is provided being capable of providing map data indicative of the positioning accuracy in areas operated by the robotic tool system. Thereby, conditions are provided for operating a robotic tool system based on the accuracy map data so as to increase safety, reliability, accuracy, and efﬁciency of the robotic tool system.

Optionally, the accuracy map data comprises current position, current time, and current positioning accuracy of a robotic tool. Thereby, a method is provided being capable of further improving safety, reliability, accuracy, and efﬁciency of the robotic tool system. This because the accuracy map data comprises data representative of current position, current time, and current positioning accuracy of a robotic tool, which subsequently can be utilized to identify areas and times at areas in which the positioning accuracy is low. The positioning accuracy of a satellite-based positioning unit depends on the current time in some situations and areas because the satellites, from which satellite-based positioning unit receives signals from, are orbiting around the earth. This means that in some situations and in some areas, the signals from the satellites may be sufﬁcient for providing an accurate positioning accuracy a certain time of a day and may be insufficient for providing an accurate positioning accuracy another time of the day. Accordingly, since the accuracy map data comprises current position, current time, and current positioning accuracy of a robotic tool when being provided, saved accuracy map data may be indicative of historical positioning accuracy in different areas/positions and historical times of positioning accuracy in different areas/positions. Saved accuracy map data may also comprise time predictions of upcoming positioning accuracy in different areas/positions. As an alternative, or in addition, the robotic tool system, and/or a control arrangement of a robotic tool, may be conﬁgured to provide time predictions of upcoming positioning accuracy in different areas/positions based on historical times of positioning accuracy in different areas/positions. Accordingly, a robotic tool system may subsequently utilize saved accuracy map data to determine when to operate certain areas and/or how to navigate robotic tools of the robotic tool system when a robotic tool is to operate an area in which the positioning accuracy is low.

Optionally, the method comprises the step of: - navigating one or more of the first robotic tool and the one or more second robotic tools at least partially based on the accuracy map data.

Thereby, a method is provided having conditions for navigating the robotic tools in a more safe, reliable, accurate, and efﬁcient manner without significantly adding costs and complexity to the robotic tool system.

According to a second aspect of the invention, the object is achieved by a robotic tool comprising a control arrangement configured to navigate the robotic tool in an area and an output unit configured to output a beacon signal receivable by an input unit of a receiving robotic tool.

Thereby, a robotic tool is provided capable ofa significantly facilitating positioning of a receiving robotic tool in a manner independent of the strength of signals from a space based satellite navigation system to the receiving robotic tool and in a manner circumventing the need for positioning fixed beacon markers in an area to be operated.

As a further result thereof, a robotic tool is provided having conditions for facilitating accurate navigation of the receiving robotic tool also in situations in which the receiving robotic tool is in an area having weak signals from a space based satellite navigation system.

Furthermore, since the robotic tool circumvents the need for positioning fixed beacon markers in an area to be operated, the robotic tool provides conditions for saving cost and complexity of a robotic tool system while providing conditions for facilitating accurate navigation of one or more robotic tools also in situations in which a robotic tool is in an area having weak signals from a space based satellite navigation system.

Accordingly, a robotic tool is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the robotic tool comprises a positioning unit conﬁgured to provide current position data of the robotic tool, and wherein the output unit is conﬁgured to output a position signal comprising the current position data. Thereby, conditions are provided for obtaining an even more accurate and reliable positioning of the receiving robotic tool.

Optionally, the robotic tool is conﬁgured to output the beacon signal upon receipt of a beacon request signal. Thereby, a robotic tool is provided having conditions for reducing the radio signal use and the energy consumption, while being capable of facilitating positioning of a receiving robotic tool in cases where the receiving robotic tool is in an area having weak signals from a space based satellite navigation system.

Optionally, the robotic tool comprises an input unit conﬁgured receive a positioning request signal from the receiving robotic tool, and wherein the control arrangement is conﬁgured to adapt the navigation of the robotic tool based on the positioning request signal. Thereby, a robotic tool is provided having conditions for facilitating positioning of a receiving robotic tool in a more efﬁcient, reliable, and accurate manner.

Optionally, the adaptation of the navigation of the robotic tool comprises at least one of: - stopping the robotic tool, - navigating the robotic tool to an area, - restricting navigation of the robotic tool to an area, - navigating the robotic tool to obtain a position relative to the receiving robotic tool and relative to a further robotic tool, and - navigating the robotic tool to a position in which an angle is obtained exceeding a threshold angle between the robotic tool and a further robotic tool measured at the position of the receiving robotic tool.

Optionally, the robotic tool is a robotic lawnmower. Thereby, a robotic lawnmower is provided having conditions for facilitating positioning of a receiving robotic lawnmower in a more efﬁcient, reliable, and accurate manner.

Thereby, a robotic lawnmower is provided capable of a signiﬁcantly facilitating positioning of a receiving robotic lawnmower in a manner independent of the strength of signals from a space based satellite navigation system to the receiving robotic lawnmower and in a manner circumventing the need for positioning fixed beacon markers in an area to be operated.

As a further result thereof, a robotic lawnmower is provided having conditions for facilitating accurate navigation of the receiving robotic lawnmower also in situations in which the receiving robotic lawnmower is in an area having weak signals from a space based satellite navigation system.

Furthermore, since the robotic lawnmower circumvents the need for positioning ﬁxed beacon markers in an area to be operated, the robotic lawnmower provides conditions for saving cost and complexity of a robotic lawnmower system while providing conditions for facilitating accurate navigation of one or more robotic lawnmowers also in situations in which a robotic lawnmower is in an area having weak signals from a space based satellite navigation system.

Accordingly, a robotic lawnmower is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a third aspect of the invention, the object is achieved by a robotic tool comprising a control arrangement configured to navigate the robotic tool in an area and an input unit conﬁgured to input a beacon signal/signals from one or more second robotic tools. The control arrangement is conﬁgured to provide a current position estimate of the robotic tool based on the received beacon signal/signals.

Thereby, a robotic tool is provided capable of providing an accurate current position estimate of the robotic tool in a manner independent of the strength of signals from a space based satellite navigation system and in a manner circumventing the need for positioning ﬁxed beacon markers in an area to be operated.As a further result thereof, a robotic tool is provided having conditions for accurate navigation also in situations in which the robotic tool is in an area having weak signals from a space based satellite navigation system.

Furthermore, since the robotic tool circumvents the need for positioning fixed beacon markers in an area to be operated, the robotic tool provides conditions for saving cost and complexity of a robotic tool system while providing conditions for an accurate navigation also in situations in which the robotic tool is in an area having weak signals from a space based satellite navigation system.

Optionally, the input unit is conﬁgured to receive current position data of the one or more second robotic tools, and wherein the control arrangement is conﬁgured to provide a current position estimate of the robotic tool based on the received current position data of the one or more second robotic tools. Thereby, even more accurate current position estimates of the robotic tool can be provided in an efﬁcient manner. This because the current position data of the one or more second robotic tools is utilized for providing the current position estimate of the robotic tool.

Optionally, the robotic tool comprises a positioning arrangement conﬁgured to provide current position data of the robotic tool, and wherein the control arrangement is conﬁgured to determine a positioning accuracy of the current position data and to output a beacon request signal if the positioning accuracy is below a threshold accuracy. Thereby, a robotic tool is provided conﬁgured to output a beacon request signal if the positioning accuracy of therobotic tool is low. Accordingly, a robotic tool is provided in which the robotic tool can request beacon signals to be sent from one or more second robotic tools in case the positioning accuracy of the robotic tool is low. Thereby, a situation-adapted robotic tool is provided capable of reducing the radio signal use and the energy consumption of the robotic tool and/or of a robotic tool system.

Optionally, the robotic tool comprises a positioning arrangement conﬁgured to provide current position data of the robotic tool, wherein the control arrangement is configured to determine a positioning accuracy of the current position data, wherein the control arrangement is conﬁgured to navigate the robotic tool using the current position data and map data of the area if the positioning accuracy is above a threshold accuracy, and wherein the control arrangement is configured to navigate the robotic tool using the current position estimate and map data of the area if the positioning accuracy is below a threshold accuracy. Thereby, a robotic tool is provided capable of navigating in an accurate and efficient manner using the current position data and map data if the positioning accuracy is high and capable of navigating in an accurate and efﬁcient manner using the current position estimate and map data of the area if the positioning accuracy is low. Thus, a robotic tool is provided capable of navigating in an accurate and efficient manner also in situations in which the robotic tool is in an area having weak signals from a space based satellite navigation system, without adding costs and complexity to a robotic tool system.

Optionally, the control arrangement is conﬁgured to determine an estimate accuracy of the current position estimate, and wherein the control arrangement is configured to restrict operation of the robotic tool if the positioning accuracy is below a threshold accuracy and if the estimate accuracy is below a threshold accuracy. Thereby, a safer and more reliable robotic tool is provided. This because the operation of the robotic tool is restricted if the robotic tool is unable to provide an accurate positioning thereof.

Optionally, the control arrangement is conﬁgured to restrict the operation of the robotic tool by stopping the robotic tool, operating the robotic tool with reduced speed, and/or changing mode of operation from a systematic operation mode to a random operation mode. Thereby, a safer and more reliable robotic tool is provided.

Optionally, the control arrangement is conﬁgured to provide accuracy map data indicative of the positioning accuracy in areas operated by the robotic tool. Thereby, a robotic tool is provided being capable of providing map data indicative of the positioning accuracy in areas operated by the robotic tool system. Thereby, conditions are provided for operating a robotictool system based on the accuracy map data so as to increase safety, reliability, accuracy, and efﬁciency of the robotic tool system.

Optionally, the accuracy map data comprises current position, current time, and current positioning accuracy of a robotic tool. Thereby, a robotic tool is provided being capable of further improving safety, reliability, accuracy, and efﬁciency of a robotic tool system. This because the accuracy map data comprises data representative of current position, current time, and current positioning accuracy of a robotic tool, which can be utilized to identify areas and times at areas in which the positioning accuracy is low. The positioning accuracy of a satellite-based positioning arrangement depends on the current time in some situations and areas because the satellites, from which satellite-based positioning arrangement receives signals from, are orbiting around the earth. This means that in some situations and in some areas, the signals from the satellites may be sufﬁcient for providing an accurate positioning accuracy a certain time of a day and may be insufficient for providing an accurate positioning accuracy another time of the day. Accordingly, since the accuracy map data comprises current position, current time, and current positioning accuracy ofa robotic tool when being provided, saved accuracy map data may be indicative of historical positioning accuracy in different areas/positions and historical times of positioning accuracy in different areas/positions. Saved accuracy map data may also comprise time predictions of upcoming positioning accuracy in different areas/positions. As an alternative, or in addition, the robotic tool system, and/or a control arrangement of a robotic tool, may be conﬁgured to provide time predictions of upcoming positioning accuracy in different areas/positions based on historical times of positioning accuracy in different areas/positions. Accordingly, a robotic tool system may subsequently utilize saved accuracy map data to determine when to operate certain areas and/or how to navigate robotic tools of the robotic tool system when a robotic tool is to operate an area in which the positioning accuracy is low.

Optionally, the input unit is configured to input beacon signals from two or more second robotic tools, and wherein the control arrangement is conﬁgured to provide a current position estimate based on the beacon signals from the two or more second robotic tools. Thereby, a robotic tool is provided having conditions for providing more accurate and reliable current position estimates.

Optionally, the robotic tool is a robotic lawnmower. Thereby, a robotic lawnmower is provided capable of providing an accurate current position estimate of the robotic lawnmower in a manner independent of the strength of signals from a space based satellite navigationsystem and in a manner circumventing the need for positioning ﬁxed beacon markers in an area to be operated.

As a further result thereof, a robotic lawnmower is provided having conditions for accurate navigation also in situations in which the robotic lawnmower is in an area having weak signals from a space based satellite navigation system.

Furthermore, since the robotic lawnmower circumvents the need for positioning ﬁxed beacon markers in an area to be operated, the robotic lawnmower provides conditions for saving cost and complexity of a robotic lawnmower system while providing conditions for an accurate navigation also in situations in which the robotic lawnmower is in an area having weak signals from a space based satellite navigation system.

According to a fourth aspect of the invention, the object is achieved by a robotic tool system comprising one or more robotic tools according to the second aspect of the invention and one or more robotic tools according to the third aspect of the invention.

Thereby, a robotic tool system is provided capable of providing accurate current position estimates of a robotic tool of the robotic tool system in a manner independent of the strength of signals from a space based satellite navigation system to the robotic tool and in a manner circumventing the need for positioning fixed beacon markers in an area to be operated.

As a further result thereof, a robotic tool system is provided having conditions for accurate navigation of one or more robotic tool also in situations in which the one or more robotic tool is/are in an area having weak signals from a space based satellite navigation system.

Furthermore, since the robotic tool system circumvents the need for positioning ﬁxed beacon markers in an area to be operated, the robotic tool system provides conditions for saving cost and complexity while providing conditions for an accurate navigation of one or more robotic tools also in situations in which the one or more robotic tools of the robotic tool system is/are in an area having weak signals from a space based satellite navigation system.

Accordingly, a robotic tool system is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the robotic tool system is a robotic lawnmower system comprising one or more robotic lawnmowers according to the second aspect of the invention and one or more robotic lawnmowers according to the third aspect of the invention.

Thereby, a robotic lawnmower system is provided capable of providing accurate current position estimates of a robotic lawnmower of the robotic lawnmower system in a manner independent of the strength of signals from a space based satellite navigation system to the robotic lawnmower and in a manner circumventing the need for positioning ﬁxed beacon markers in an area to be operated.

As a further result thereof, a robotic lawnmower system is provided having conditions for accurate navigation of one or more robotic lawnmower also in situations in which the one or more robotic lawnmower is/are in an area having weak signals from a space based satellite navigation system.

Furthermore, since the robotic lawnmower system circumvents the need for positioning fixed beacon markers in an area to be operated, the robotic lawnmower system provides conditions for saving cost and complexity while providing conditions for an accurate navigation of one or more robotic lawnmowers also in situations in which the one or more robotic lawnmowers of the robotic lawnmower system is/are in an area having weak signals from a space based satellite navigation system.

Accordingly, a robotic lawnmower system is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above- mentioned object is achieved.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which:Fig. 1 schematically illustrates a robotic tool according to some embodiments, Fig. 2 illustrates a robotic tool system, according to some embodiments, Fig. 3 illustrates a method of providing a current position estimate of a ﬁrst robotic tool of a robotic tool system.

DETAILED DESCRIPTION Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig. 1 schematically illustrates a self-propelled autonomous robotic tool r1, r2, r2', r2" according to some embodiments of the present disclosure. The self-propelled autonomous robotic tool r1, r2, r2', r2" is in some places herein referred to as a “robotic tool r1, r2, r2', r2" for the reason of brevity and clarity. As is further explained herein, the robotic tool r1, r2, r2', r2" is capable of navigating and operating in an area in an autonomous manner without the intervention or the direct control of a user. According to the illustrated embodiments, the robotic tool r1, r2, r2', r2" is a self-propelled autonomous robotic lawnmower r1, r2, r2', r2" capable of navigating and cutting grass in an autonomous manner in an area without the intervention or the direct control of a user. Therefore, throughout this disclosure, the wording “robotic tool" may be replaced with the wording “robotic lawnmower”. According to the illustrated embodiments, the robotic lawnmower r1, r2, r2', r2" is configured to be used to cut grass in areas used for aesthetic and recreational purposes, such as gardens, parks, golf fields, city parks, sports fields, lawns around houses, apartments, commercial buildings, ofﬁces, and the like.

According to further embodiments of the present disclosure, the robotic tool r1, r2, r2', r2", as referred to herein, may be another type of robotic tool r1, r2, r2', r2" than a robotic lawnmower, such as a robotic golf ball collecting tool, a robotic vacuum cleaner, a robotic floor cleaner, a robotic snow removal tool, a robotic mine clearance robot, a robotic leaves blower, a robotic leaves collector, or the like.

The robotic tool r1, r2, r2', r2" comprises a chassis 3 and a number of wheels 4, 5 supporting the chassis 3 by abutting against a ground surface during operation of the robotic tool r1, r2, r2', r2". ln Fig. 1, only three wheels 4, 5 are visible, namely two support wheels 5 and one drive wheel 4. However, according to the illustrated embodiments, the robotic tool r1, r2, r2', r2" comprises four wheels 4, 5, namely two drive wheels 4 and two support wheels 5. Thedrive wheels 4 of the robotic tool r1, r2, r2', r2" may each be powered by a propulsion motor of the robotic tool r1, r2, r2', r2" to provide motive power and/or steering of the robotic tool r1, r2, r2', r2". The robotic tool r1, r2, r2', r2" may thus comprise one propulsion motor per drive wheel 4, wherein the propulsion motor/motors is/are conﬁgured to rotate a drive wheel 4. The robotic tool r1, r2, r2', r2" may comprise a transmission between the respective propulsion motor and drive wheel 4. The propulsion motor/motors may comprise an electrical motor.

According to the illustrated embodiments, the drive wheels 4 of the robotic tool r1, r2, r2', r2" are non-steered wheels having a fix rolling direction in relation to the chassis 3. The respective rolling direction of the drive wheels 4 of the robotic tool r1, r2, r2', r2" is substantially parallel to a longitudinal direction of the robotic tool r1, r2, r2', r2". According to the illustrated embodiments, the support wheels 5 are non-driven wheels. lVloreover, according to the illustrated embodiments, the support wheels 5 can pivot around a respective pivot axis such that the rolling direction of the respective support wheel 5 can follow a travel direction of the robotic tool r1, r2, r2', r2".

According to the illustrated embodiments, the robotic tool r1, r2, r2', r2" may be referred to as a four-wheeled rear wheel driven robotic tool r1, r2, r2', r2". According to further embodiments, the robotic tool r1, r2, r2', r2" may be provided with another number of wheels 4, 5, such as three wheels. Moreover, according to further embodiments, the robotic tool r1, r2, r2', r2" may be provided with another configuration of driven and non-driven wheels, such as a front wheel drive or an all-wheel drive. According to still further embodiments, the robotic tool r1, r2, r2', r2" may comprise another type of support unit 5 or drive unit 4 than a wheel 4, 5, such as a continuous track arrangement, or the like.

The robotic tool r1, r2, r2', r2" may comprise one or more cutting units conﬁgured to cut vegetation during operation of the robotic tool r1, r2, r2', r2". The cutting unit/cutting units may comprise a cutting disc provided with a number of cutting members arranged at a periphery of the cutting disc. Moreover, the robotic tool r1, r2, r2', r2" may comprise a motor configured to rotate one or more cutting units.

The robotic tool r1, r2, r2', r2" comprises a control arrangement 21. According to the pormatted; Portuguese (portugan illustrated embodiments, the control arrangement 21 is conﬁgured to navigate the robotic tool r1, r2, r2', r2" by controlling rotation of the drive wheels 4 of the robotic tool r1, r2, r2', r2". According to further embodiments, the control arrangement 21 may be configured to navigate the robotic tool r1, r2, r2', r2" by controlling a steering angle of steered wheels of the robotic tool r1, r2, r2', r2" and/or by controlling propulsion of a propulsion unit other thanwheels, such as a continuous track arrangement. The control arrangement 21 is configured to navigate the robotic tool r1, r2, r2', r2" in an area using input from different sensors and input units 6, 23, as is further explained herein. ln more detail, according to the i||ustrated embodiments, the robotic tool r1, r2, r2', r2" comprises a positioning arrangement 23. The positioning arrangement 23 is conﬁgured to provide current position data of the robotic tool r1, r2, r2', r2". The positioning arrangement 23 may also be referred to as a positioning unit 23. According to the i||ustrated embodiments, the positioning arrangement 23 is a satellite-based positioning arrangement 23 conﬁgured to receive signals from a number of satellites 25 so as to provide current position data of the robotic tool r1, r2, r2', r2". Thus, according to the i||ustrated embodiments, the positioning arrangement 23 is configured to utilize a space based satellite navigation system, such as a Global Positioning System (GPS), The Russian GLObal NAvigation Satellite System (GLONASS), European Union Galileo positioning system, Chinese Compass navigation system, or Indian Regional Navigational Satellite System, to provide current satellite-based position data of the robotic tool r1, r2, r2', r2" Therefore, throughout this disclosure, the wording “current position data" may be replaced with the wording “current satellite-based position data".

Moreover, the robotic tool r1, r2, r2', r2" comprises an output unit 2 conﬁgured to output a beacon signal receivable by an input unit 6 of a receiving robotic tool r1, r2, r2', r2". The robotic tool r1, r2, r2', r2" i||ustrated in Fig. 1 comprises an output unit 2 as well as an input unit 6. According to further embodiments, the robotic tool r1, r2, r2', r2", as referred to herein, may comprise one of the output unit 2 and the input unit 6. Since the output unit 2 is configured to output a beacon signal, the output unit 2 may also be referred to as a “beacon output unit 2" or “beacon marker 2". Likewise, since the input unit 6 is conﬁgured to input a beacon signal, the input unit 6 may also be referred to as a “beacon input unit 6" or “beacon sensor 6".

Fig. 2 illustrates a robotic tool system 1, according to some embodiments, as operating an area A1, A2. According to the i||ustrated embodiments, the area A1, A2 is a golf course. Moreover, according to the i||ustrated embodiments, the robotic tool system 1 comprises four robotic tools r1, r2, r2', r2" according to the embodiments i||ustrated in Fig. 1. Therefore, below, simultaneous reference is made to Fig. 1 and Fig. 2, if not indicated otherwise. According to further embodiments, the robotic tool system 1, as referred to herein, may comprise another number of robotic tools r1, r2, r2', r2". According to some embodiments, the robotic tool system 1 comprises at least one robotic tool r1, r2, r2', r2" comprising aninput unit 6 and at least one robotic tool r1, r2, r2', r2" comprising an output unit 2. The robotic tools r1, r2, r2', r2" of the robotic tool system 1 may thus be differently configured. However, according to the illustrated embodiments the four robotic tools r1, r2, r2', r2" of the robotic tool system 1 have the same configuration, i.e. comprises the same features, functions, and arrangements. According to the illustrated embodiments, the four robotic tools r1, r2, r2', r2" comprise a first robotic tool r1 and three second robotic tools r2, r2', r2". For the reason of brevity and clarity, the reference sign 9 is used in Fig. 2 for indicating the output unit 2, the input unit 6, the control arrangement 21, and the positioning arrangement 23 of the respective robotic tool r1, r2, r2', r2". ln Fig. 2, each of the second robotic tools r2, r2', r2" is located in a first area A1 in which signals from the space based satellite navigation system are strong enough to provide accurate current position data of the second robotic tools r2, r2', r2". However, the ﬁrst robotic tool r1 is located in a second area A2 in which the signals from the space based satellite navigation system are relative weak since signals from satellites 25 are blocked by some objects 27. Therefore, in Fig. 2, the positioning arrangement 23 of the first robotic tool r1 is unable to provide accurate positioning data of the ﬁrst robotic tool r However, as explained herein, each of the second robotic tools r2, r2', r2" comprises an output unit 2 configured to output a beacon signal Bs receivable by an input unit 6 of a ﬁrst robotic tool r1. The input unit 6 of the first robotic tool r1 is configured to input beacon signal/signals Bs from one or more second robotic tools r2, r2', r2". Moreover, the control arrangement 21 of the ﬁrst robotic tool r1 is conﬁgured to provide a current position estimate of the ﬁrst robotic tool r1 based on the received beacon signal/signals Bs. ln this manner, accurate current position estimates can be obtained of the first robotic tool r1 also in situations in which the ﬁrst robotic tool is in an area A2 in which signals from satellites 25 ofa space based satellite navigation system are weak. Thereby, the ﬁrst robotic tool r1 is allowed to continue to operate also in such situations and in such areas A2. Moreover, since the beacon signals Bs are sent from the second robotic tools r2, r2', r2", there is no need for placing stationary beacon markers in an area A1, A2, to be operated by the robotic tool system 1 _ Obviously, the wording "first" and "second" as used herein is only used to distinguish between the robotic tools r1, r2, r2', r2" of the robotic tool system 1 in a clear manner. That is, the “ﬁrst robotic tool r1" as referred to herein, may also be referred to as a “receiving robotic tool r1", as is the case in some places herein, or simply “a robotic tool r1". The robotic tool system 1 may comprise more than one first robotic tool r1, i.e. more than one receiving robotic tool r1. Likewise, the “second robotic tools r2, r2', r2"" as referred to herein, may also be referred to as a “sending robotic tool r2, r2', r2"", and/or a “second robotic tool r2", a “third robotic tool r2'", and a “fourth robotic tool r2"", or simply “a robotic tool r2, r2', r2".

Furthermore, as indicated above, the robotic tool system 1 may comprise another number of second robotic tools r2, r2', r2" than three.

According to some embodiments, the control arrangement 21 of the first robotic tool r1 is configured to estimate a distance/distances to the second robotic tools r2, r2', r2" based on the beacon signal/signals Bs. ln this manner, conditions are provided for obtaining accurate current position estimates of the ﬁrst robotic tool r According to some embodiments herein, the control arrangement 21 of the first robotic tool r1 is configured to estimate an angle/angles a1, a2, a3 of arrival of the beacon signal/signals Bs at the ﬁrst robotic tool r1. This may be achieved by the input unit 6 being conﬁgured to detect angle/angles a1, a2, a3 of arrival of the beacon signal/signals Bs. The angle/angles a1, a2, a3 of arrival of the beacon signal/signals Bs may be related to a current orientation Co of the first robotic tool 1. By estimating the angle/angles a1, a2, a3 of arrival of the beacon signal/signals Bs at the first robotic tool r1, conditions are provided for obtaining accurate current position estimates of the ﬁrst robotic tool r1 also in cases of a lower number of second robotic tools r2, r2', r2" than three.

The output unit 2 of the second robotic tools r2, r2', r2" may be a radio frequency beacon emitting a radio frequency signal and the input unit 6 of the first robotic tool r1 may be a radio frequency receiver or transceiver. According to some embodiments, the output unit 2 of the second robotic tools r2, r2', r2" may be an ultrasonic beacon emitting an ultrasonic signal and the input unit 6 of the ﬁrst robotic tool r1 may be an ultrasonic receiver or transceiver. The output unit 2 of the second robotic tools r2, r2', r2" and the input unit 6 of the first robotic tool r1 may thus utilize ultra-wideband radio technology, also known as UWB, ultra-wide band and ultraband radio technology.

According to some embodiments, the control arrangement 21 of the first robotic tool r1 is configured to estimate a distance/distances to the second robotic tools r2, r2', r2", i.e. a proximity/proximities to the second robotic tools r2, r2', r2", by estimating a time of flight of the beacon signal/signals Bs.

According to some embodiments, the control arrangement 21 of the first robotic tool r1 is configured to estimate a distance/distances to the second robotic tools r2, r2', r2", i.e. aproximity/proximities to the second robotic tools r2, r2', r2", by comparing a signal strength of the beacon signal/signals Bs to a number of threshold values.

According to some embodiments, the control arrangement 21 of the first robotic tool r1 is configured to estimate a distance/distances to the second robotic tools r2, r2', r2", i.e. a proximity/proximities to the second robotic tools r2, r2', r2", by comparing the signal strength of the beacon signal/signals Bs to a model of signal declination.

According to some embodiments, the control arrangement 21 of the first robotic tool r1 is configured to estimate a distance/distances to the second robotic tools r2, r2', r2", i.e. a proximity/proximities to the second robotic tools r2, r2', r2", by sending a signal to the second robotic tools r2, r2', r2" and measure the two-way response time.

According to some embodiments, the control arrangement 21 of the first robotic tool r1 is configured to estimate a distance/distances to the second robotic tools r2, r2', r2", i.e. a proximity/proximities to the second robotic tools r2, r2', r2", by monitoring the phase of the beacon signal/signals Bs and by comparing the phase to a number of threshold values and/or to a phase model.

According to some embodiments, the output unit 2 of the second robotic tools r2, r2', r2" may be conﬁgured to output current satellite-based position data of the second robotic tools r2, r2', r2". The current satellite-based position data of the second robotic tools r2, r2', r2" may be comprised in the beacon signals Bs. The input unit 6 of the ﬁrst robotic tool r1 may be configured to receive the current position data of the one or more second robotic tools r2, r2', r2". Moreover, the control arrangement 21 of the ﬁrst robotic tool r1 may be configured to provide a current position estimate of the robotic tool r1 based on the received current position data of the one or more second robotic tools r2, r2', r2". ln this manner, even more accurate current position estimates of the first robotic tool r1 can be provided in an efﬁcient manner.

According to the illustrated embodiments, the robotic tool system 1 comprises a reference station 61 of a real-time kinematic (RTK) system. Real-time kinematic (RTK) positioning is a satellite navigation technique used to increase the precision of position data derived from a satellite-based positioning system. Real-time kinematic uses measurements of the phase of a carrier wave of a signal in addition to information content of the signal and uses the reference station 61 to provide real-time corrections of positioning data. According to the illustrated embodiments, the reference station 61 sends real-time corrections to the robotictools r1, r2, r2', r2" via a wireless transmission channel. As an alternative, or in addition, real- time corrections of the positioning data may also be sent via a virtual reference station using e.g. a local area network, such as Wi-Fi, a cellular network, or another type of wireless channel. Thereby, the respective positioning arrangement 23 of the robotic tools r2, r2', r2" can provide even more accurate current position data of the robotic tools r2, r2', r2". Thus, in embodiments in which the control arrangement 21 of the ﬁrst robotic tool r1 is configured to provide a current position estimate of the robotic tool r1 based on the received current position data of the one or more second robotic tools r2, r2', r2", even more accurate current position estimates of the first robotic tool r1 can be provided when using real-time corrections of the current position data of the second robotic tools r2, r2', r2".

According to some embodiments, the ﬁrst robotic tool r1 comprises a positioning arrangement 23 configured to provide current satellite-based position data of the robotic tool r1, and wherein the control arrangement 21 of the ﬁrst robotic tool r1 is configured to determine a positioning accuracy of the current position data and to output a beacon request signal if the positioning accuracy is below a threshold accuracy. The threshold accuracy may be set to a level in which it is determined that positioning accuracy is insufficient for a further accurate navigation of the first robotic tool r1. Moreover, the second robotic tools r2, r2', r2" may be conﬁgured to output the beacon signal Bs upon receipt of a beacon request signal. ln this manner, the radio signal use and the energy consumption of the robotic tool system 1 can be lowered as compared to embodiments in which the output units 2 of the robotic tools r1, r2, r2', r2" are constantly outputting beacon signals Bs.

Moreover, according to some embodiments herein, the output unit 2 of the ﬁrst robotic tool r1 may be conﬁgured to output a positioning request signal. The control arrangement 21 of the first robotic tool r1 may be configured to determine an estimate accuracy of the current position estimate and may request an output of a positioning request signal from the ﬁrst robotic tool r1 if the estimate accuracy is below a threshold accuracy. The input units 6 of the second robotic tools r2, r2', r2" may each be conﬁgured receive a positioning request signal from the first robotic tool r1. The control arrangements 21 of the second robotic tools r2, r2', r2" may each be configured to adapt the navigation of the robotic tool r2, r2', r2" based on the positioning request signal.

According to some embodiments, the adaptation of the navigation of the second robotic tool r2, r2', r2" comprises stopping the robotic tool r2, r2', r2". ln this manner, the control arrangement 21 of the ﬁrst robotic tool r1 can in a simpler and more reliable manner providea current position estimate of the robotic tool r1 based on the received beacon signal/signals Bs.

As an alternative, or in addition, the adaptation of the navigation of the second robotic tool r2, r2', r2" may comprise navigating the second robotic tool r2, r2', r2" to an area Ar1, Ar2, Ar3. The area Ar1, Ar2, Ar3 may be a predeﬁned area Ar1, Ar2, Ar3 ensuring efﬁcient transfer of beacon signals from the second robotic tools r2, r2', r2" to the first robotic tool r1, and/or an area Ar1, Ar2, Ar3 ensuring a certain geometrical distribution of the second robotic tools r2, r2', r2". Thereby, the control arrangement 21 of the first robotic tool r1 can in more reliable manner provide a current position estimate of the robotic tool r1 based on the received beacon signal/signals Bs.

As an alternative, or in addition, the adaptation of the navigation of the second robotic tool r2, r2', r2" may comprise restricting navigation of the robotic tool r2, r2', r2" to an area Ar1, Ar2, Ar3. The area Ar1, Ar2, Ar3 may be a predeﬁned area ensuring efficient transfer of beacon signals from the second robotic tool r2, r2', r2" to the first robotic tool r1, and/or an area Ar1, Ar2, Ar3 ensuring a certain geometrical distribution of the second robotic tools r2, r2', r2". Thereby, the control arrangement 21 of the ﬁrst robotic tool r1 can in more reliable manner provide a current position estimate of the robotic tool r1 based on the received beacon signal/signals Bs.

As an alternative, or in addition, the adaptation of the navigation of the second robotic tool r2, r2', r2" may comprise navigating the robotic tool r2, r2', r2" to obtain a position relative to the receiving robotic tool r1 and relative to a further robotic tool r2, r2', r2". The position may be a predefined position relative to the receiving robotic tool r1 and relative to a further robotic tool r2, r2', r2" which facilitates the provision of current position estimates of the first robotic tool r1 based on the received beacon signal/signals Bs.

As an alternative, or in addition, the adaptation of the navigation of the second robotic tool r2, r2', r2" may comprise navigating the robotic tool r2, r2', r2" to a position in which an angle a4, a5 is obtained exceeding a threshold angle between the robotic tool r2, r2', r2" and a further robotic tool r2, r2', r2" measured at the position of the receiving robotic tool r1. Thereby, the control arrangement 21 of the ﬁrst robotic tool r1 can in a simpler and more reliable manner provide a current position estimate of the robotic tool r1 based on the received beacon signal/signals Bs.According to some embodiments, the output unit 2 of the second robotic tools r2, r2', r2" may be conﬁgured to output travel data of the respective second robotic tool r2, r2', r2" to the first robotic tool r1. The travel data may comprise current velocity and current heading direction of the second robotic tool r2, r2', r2". ln this manner, the control arrangement 21 of the ﬁrst robotic tool r1 can calculate current positions of the respective second robotic tool r2, r2', r2" even after a certain amount of time so as to provide a current position estimate of the first robotic tool r1. According to some embodiments, the travel data may comprise an upcoming travel path or trajectory of the second robotic tool r2, r2', r2". Thereby, the control arrangement 21 of the ﬁrst robotic tool r1 can calculate current positions of the respective second robotic tool r2, r2', r2" even after a certain amount of time with higher accuracy so as to provide a current position estimate of the first robotic tool r According to some embodiments of the present disclosure, the positioning arrangement 23 of the first robotic tool r1 is conﬁgured to provide current satellite-based position data of the robotic tool r1, wherein the control arrangement 21 of the first robotic tool r1 is conﬁgured to determine a positioning accuracy of the current satellite-based position data. According to such embodiments, the control arrangement 21 may be configured to navigate the robotic tool r1 using the current position data and map data of the area A1 if the positioning accuracy is above a threshold accuracy, and may be conﬁgured to navigate the robotic tool r1 using the current position estimate and map data of the area A2 if the positioning accuracy is below a threshold accuracy.

According to some embodiments, the control arrangement 21 of the first robotic tool r1 is configured to determine an estimate accuracy of the current position estimate, and wherein the control arrangement 21 is conﬁgured to restrict operation of the robotic tool r1 if the positioning accuracy is below a threshold accuracy and if the estimate accuracy is below a threshold accuracy. The control arrangement 21 may be configured to restrict the operation of the robotic tool r1 by stopping the robotic tool r1, operating the robotic tool r1 with reduced speed, and/or changing mode of operation from a systematic operation mode to a random operation mode.

According to some embodiments of the present disclosure, the control arrangement 21 is configured to provide accuracy map data indicative of the positioning accuracy in areas A1, A2 operated by the robotic tool r1, r2, r2', r2". The accuracy map data may be representative of current position, current time, and current positioning accuracy of a robotic tool r1, r2, r2', r2" when being provided. Thereby, the accuracy map data can subsequently be utilized to identify areas and times at areas in which the positioning accuracy is low. The positioning accuracy of a satellite-based positioning arrangement depends on the current time in some situations and areas because the satellites 25, from which a satellite-based positioning arrangement 23 receives signals from, are orbiting around the earth. This means that in some situations and in some areas, the signals from the satellites 25 may be sufﬁcient for providing an accurate positioning a certain time ofa day and may be insufficient for providing an accurate positioning another time of the day. Accordingly, since the accuracy map data comprises current position, current time, and current positioning accuracy of a robotic tool r1 when being provided, saved accuracy map data may be indicative of historical positioning accuracy in different areas/positions and historical times of positioning accuracy in different areas/positions. Saved accuracy map data may also comprise time predictions of upcoming positioning accuracy in different areas/positions. As an alternative, or in addition, the robotic tool system 1, and/or a control arrangement 21 of a robotic tool r1, may be configured to provide time predictions of upcoming positioning accuracy in different areas/positions based on historical times of positioning accuracy in different areas/positions. Accordingly, the robotic tool system 1 may subsequently utilize saved accuracy map data to determine when to operate certain areas A1, A2 and/or how to navigate robotic tools r1, r2, r2', r2" of the robotic tool system 1 when a robotic tool r1, r2, r2', r2" is to operate an area A2 in which the positioning accuracy is low. Thereby, the time needed for operating areas A2 having weak signals from satellites 25 of a space based satellite navigation system can be minimized.

The positioning arrangement 23 of the robotic tool r1, r2, r2', r2" may comprise other types of sensors or arrangements for providing, verifying, and/or updating current position data and/or current position estimates of the robotic tool r1, r2, r2', r2". As an example, the positioning arrangement 23 may comprise an inclination angle sensor conﬁgured to sense a current inclination angle of the robotic tool r1, r2, r2', r2" relative a horizontal plane. The inclination angle sensor may be configured to sense the orientation of the robotic tool r1, r2, r2', r2" relative to the gravitational ﬁeld at the location of the robotic tool r1, r2, r2', r2" to thereby sense the current inclination angle of the robotic tool r1, r2, r2', r2" relative a horizontal plane. According to such embodiments, the inclination angle sensor may comprise an accelerometer. As an alternative, or in addition, the inclination angle sensor may be configured to sense angular displacements of the robotic tool r1, r2, r2', r2". According to such embodiments, the inclination angle sensor may comprise a gyroscope. Moreover, the control arrangement 21 may be arranged to obtain reference values at one or more predetermined locations, such as at a charging dock. The control arrangement 21 of the robotic tool r1, r2, r2', r2" may compare the current inclination angle of the robotic tool r1, r2, r2', r2" with map data comprising inclination data of the area A1, A2 to provide, verify, and/orupdate current position data and/or current position estimates of the robotic tool r1, r2, r2', r2'.

As another example, the positioning arrangement 23 of the robotic tool r1, r2, r2', r2" may comprise one or more odometers or odographs arranged to monitor rotation of a wheel 4, 5 of the robotic tool r1, r2, r2', r2". According to some embodiments, the positioning arrangement 23 of the robotic tool r1, r2, r2', r2" comprises two odometers each arranged to monitor rotation of a wheel 4, 5 of the robotic tool r1, r2, r2', r2". Thereby, conditions are provided for providing, verifying, and/or updating current position data and/or current position estimates of the robotic tool r1, r2, r2', r2" by comparing data of the odometers or odographs with historic current position data and/or historic current position estimates of the robotic tool r1, r2, r2', r2".

As another example, the positioning arrangement 23 of the robotic tool r1, r2, r2', r2" may comprise one or more sensors for detecting an event, such as a collision event with an object 27 within an area A1, A2. The control arrangement 21 of the robotic tool r1, r2, r2', r2" may use map data of the area A1, A2 to provide, verify, and/or update current position data and/or current position estimates of the robotic tool r1, r2, r2', r2' based on a detected collision event with an object As mentioned above, according to the illustrated embodiments, the area A1, A2 operated by the robotic tool system 1 is a golf course. However, obviously, the robotic tool system 1 according to the present disclosure may be used to operate another type of area. According to the illustrated embodiments, map data of the area A1, A2 is obtained via a so called walk the dog procedure in which a user is manually guiding a robotic tool r1, r2, r2', r2" of the robotic tool system 1 around boundaries 29 of an area A1, A2 to be operated. The manual guiding of a robotic tool r1, r2, r2', r2" may include remote control of the robotic tool r1, r2, r2', r2". As an alternative, or in addition, the boundaries 29 of an area A1, A2 to be operated may be inputted to map data in another manner, such as via a computer, a computer tablet, and/or a smartphone. The map data may be stored locally in a memory of the respective robotic tool r1, r2, r2', r2" of the robotic tool system 1 and/or externally in an external database wherein the map data may be wirelessly transmitted to the respective robotic tool r1, r2, r2', r2" of the robotic tool system Fig. 3 illustrates a method 100 of providing a current position estimate ofa first robotic tool of a robotic tool system. The robotic tool system may be a robotic tool system 1 according to the embodiments illustrated in Fig. 2, i.e. a robotic tool system 1 comprising a first robotic toolr1 and one or more second robotic tools r2, r2', r2". Below, simultaneous reference is made to Fig. 1 - Fig.

The method 100 illustrated in Fig. 3 is a method 100 of providing a current position estimate of a first robotic tool r1 of a robotic tool system 1, wherein the robotic tool system 1 comprises the first robotic tool r1 and one or more second robotic tools r2, r2', r2", and wherein the method 100 comprises the steps of: - outputting 110 a beacon signal/signals Bs from the one or more second robotic tools r2, r2', r2", - receiving 130 the beacon signal/signals Bs at the first robotic tool r1, and - providing 150 a current position estimate of the ﬁrst robotic tool r1 based on the received beacon signal/signals Bs.

As indicated in Fig, 3, the method 100 may comprise the steps of: - obtaining 152 a relative distance/distances between the first robotic tool r1 and the one or more second robotic tools r2, r2', r2" based on the beacon signal/signals Bs, and - providing 154 the current position estimate of the ﬁrst robotic tool r1 based on the obtained relative distance/distances.

Moreover, as indicated in Fig, 3, the method 100 may comprise the steps of: - estimating 156 an angle/angles a1, a2, a3 of arrival of the beacon signal/signals Bs at the ﬁrst robotic tool r1, and - providing 158 the current position estimate of the ﬁrst robotic tool r1 based on the estimated angle/angles a1, a2, a Furthermore, as indicated in Fig, 3, the method 100 may comprise the steps of: - providing 160 current position data of the one or more second robotic tools r2, r2', r2", and - providing 166 the current position estimate of the ﬁrst robotic tool r1 based on the current position data of the one or more second robotic tools r2, r2', r2".

Moreover, as indicated in Fig, 3, the method 100 may comprise the steps of: - outputting 162 the current position data from the one or more second robotic tools r2, r2', r2", and - receiving 164 the current position data at the first robotic tool rObviously, the steps of outputting 162 the current position data from the one or more second robotic tools r2, r2', r2" and receiving 164 the current position data at the ﬁrst robotic tool r1 may be performed prior to the step of providing 166 the current position estimate of the first robotic tool r1 based on the current position data of the one or more second robotic tools r2, r2', r2".

Furthermore, as indicated in Fig, 3, the method 100 may comprise the steps of: - providing 102 current position data of the ﬁrst robotic tool r1, - determining 104 a positioning accuracy of the current position data of the ﬁrst robotic tool r1, and - outputting 106 a beacon request signal if the positioning accuracy of the current position data is below a threshold accuracy.

Moreover, as indicated in Fig, 3, the method 100 may comprise the steps of: - outputting 112 the beacon signal/signals Bs from the one or more second robotic tools r2, r2', r2" upon receipt of a beacon request signal.

Moreover, as indicated in Fig, 3, the method 100 may comprise the steps of: - outputting 170 a positioning request signal from the first robotic tool r1, - receiving 172 the positioning request signal in the one or more second robotic tools r2, r2', r2", and - adapting 174 the navigation of the one or more second robotic tools r2, r2', r2" based on the positioning request signal.

As indicated in Fig. 3, the step of adapting 174 the navigation of the one or more second robotic tools r2, r2', r2" may comprise at least one of the steps: - stopping 175 at least one of the one or more second robotic tools r2, r2', r2", - navigating 176 at least one of the one or more second robotic tools r2, r2', r2" to an area Ar1, Ar2, Ar3, and - restricting navigation 177 of at least one of the one or more second robotic tools r2, r2', r2" to an area Ar1, Ar2, Ar According to some embodiments, the robotic tool system 1 comprises two or more second robotic tools r2, r2', r2", and wherein the step of adapting 174 the navigation of the two or more second robotic tools r2, r2', r2" comprises: - navigating 178 at least one of the two or more second robotic tools r2, r2', r2" to obtain an angle a4, a5 exceeding a threshold angle between two of the two ormore second robotic tools r2, r2', r2" measured at the position of the first robotic tool r As indicated in Fig. 3, the method 100 may comprise the steps of: - providing 102 current position data of the ﬁrst robotic tool r1, - determining 104 a positioning accuracy of the current position data of the ﬁrst robotic tool r1, - determining 180 an estimate accuracy of the current position estimate, and - restricting 185 operation of the first robotic tool r1 if the positioning accuracy is below a threshold accuracy and if the estimate accuracy is below a threshold aCCLl faCy.

According to some embodiments, the step of restricting 185 the operation of the ﬁrst robotic tool r1 comprises at least one of: - stopping 186 the ﬁrst robotic tool r1, - operating 187 the first robotic tool r1 with reduced speed, and - changing 188 mode of operation from a systematic operation mode to a random operation mode.

As indicated in Fig. 3, the method 100 may comprise the steps of: - providing 102 current position data of the ﬁrst robotic tool r1, - determining 104 a positioning accuracy of the current position data of the ﬁrst robotic tool r1, - providing 190 accuracy map data indicative of the positioning accuracy in areas A1, A2 operated by the robotic tool system 1 based on the determined positioning accuracy.

According to some embodiments, the accuracy map data comprises current position, current time, and current positioning accuracy of a robotic tool r1 when being provided.

As indicated in Fig. 3, the method 100 may comprise the step of: - navigating 192 one or more of the first robotic tool r1 and the one or more second robotic tools r2, r2', r2" at least partially based on the accuracy map data. lt will be appreciated that the various embodiments described for the method 100 are all combinable with the control arrangement 21 as described herein. That is, the control arrangement 21 may be conﬁgured to perform any one of the method steps of the method One skilled in the art will appreciate the control performed by the control arrangement 21 described herein may be implemented by programmed instructions. These programmed instructions are typically constituted by a computer program, which, when it is executed in the control arrangement 21, ensures that the control arrangement 21 carries out the desired control. The computer program is usually part of a computer program product which comprises a suitable digital storage medium on which the computer program is stored.

The control arrangement 21 may comprise a calculation unit which may take the form of substantially any suitable type of processor circuit or microcomputer, e.g. a circuit for digital signal processing (digital signal processor, DSP), a Central Processing Unit (CPU), a processing unit, a processing circuit, a processor, an Application Specific Integrated Circuit (ASIC), a microprocessor, or other processing logic that may interpret and execute instructions. The herein utilised expression “calculation unit" may represent a processing circuitry comprising a plurality of processing circuits, such as, e.g., any, some or all of the ones mentioned above.

The control arrangement 21 may further comprise a memory unit, wherein the calculation unit may be connected to the memory unit, which may provide the calculation unit with, for example, stored program code and/or stored data which the calculation unit may need to enable it to do calculations. The calculation unit may also be adapted to store partial or final results of calculations in the memory unit. The memory unit may comprise a physical device utilised to store data or programs, i.e., sequences of instructions, on a temporary or permanent basis. According to some embodiments, the memory unit may comprise integrated circuits comprising silicon-based transistors. The memory unit may comprise e.g. a memory card, a ﬂash memory, a USB memory, a hard disc, or another similar volatile or non-volatile storage unit for storing data such as e.g. ROM (Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (Erasable PROM), EEPROM (Electrically Erasable PROM), etc. in different embodiments.

The control arrangement 21 is connected to components of the robotic tool r1, r2, r2', r2" for receiving and/or sending input and output signals. These input and output signals may comprise waveforms, pulses, or other attributes which the input signal receiving devices can detect as information and which can be converted to signals processable by the control arrangement 21. These signals may then be supplied to the calculation unit. One or moreoutput signal sending devices may be arranged to convert calculation results from the calculation unit to output signals for conveying to other parts of the control system and/or the component or components for which the signals are intended. Each of the connections to the respective components of the robotic tool r1, r2, r2', r2" for receiving and sending input and output signals may take the form of one or more from among a cable, a data bus, e.g. a CAN (controller area network) bus, or some other bus configuration, or a wireless connection. ln the embodiments illustrated, the robotic tool r1, r2, r2', r2" comprises a control arrangement 21 but might alternatively be implemented wholly or partly in two or more control arrangements or two or more control units.

The computer program product may be provided for instance in the form of a data carrier carrying computer program code for performing the desired control when being loaded into one or more calculation units of the control arrangement 21. The data carrier may be, e.g. a CD ROM disc, or a ROM (read-only memory), a PROM (programable read-only memory), an EPROM (erasable PROM), a flash memory, an EEPROM (electrically erasable PROM), a hard disc, a memory stick, an optical storage device, a magnetic storage device or any other appropriate medium such as a disk or tape that may hold machine readable data in a non- transitory manner. The computer program product may furthermore be provided as computer program code on a server and may be downloaded to the control arrangement 21 remotely, e.g., over an Internet or an intranet connection, or via other wired or wireless communication systems.

The control arrangement 21 may be configured to control propulsion of the robotic tool r1, r2, r2', r2", and steer the robotic tool r1, r2, r2', r2", so as to navigate the robotic tool r1, r2, r2', r2" in an area to be operated. The robotic tool r1, r2, r2', r2" may further comprise one or more sensors arranged to sense a magnetic ﬁeld of a wire, and/or one or more positioning units, and/or one or more sensors arranged to detect an impending or ongoing collision event with an object. The one or more positioning units may comprise a space based satellite navigation system such as a Global Positioning System (GPS), The Russian GLObal NAvigation Satellite System (GLONASS), European Union Galileo positioning system, Chinese Compass navigation system, or Indian Regional Navigational Satellite System. As an alternative, or in addition, the control arrangement 21 may be conﬁgured to obtain data from, or may comprise, one or more positioning units utilizing a local reference source, such as a local sender and/or a wire, to estimate or verify a current position of the robotic tool r1, r2, r2', r2".ln addition, the robotic tool r1, r2, r2', r2" may comprise a communication unit connected to the control arrangement 21. The communication unit may be configured to communicate with a remote communication unit to receive instructions therefrom and/or to send information thereto. The communication may be performed wirelessly over a wireless connection such as the internet, or a wireless local area network (WLAN), or a wireless connection for exchanging data over short distances using short-wavelength, i.e. ultra-high frequency (UHF) radio waves in the industrial, scientific, and medical (ISM) band from 2.4 to 2.485 GHz.

The control arrangement 21 may be configured to control propulsion of the robotic tool r1, r2, r2', r2", and steer the robotic tool r1, r2, r2', r2", so as to navigate the robotic tool r1, r2, r2', r2" in a systematic and/or random pattern to ensure that an area is completely covered, using input from one or more of the above described sensors and/or units. Furthermore, the robotic tool r1, r2, r2', r2" may comprise one or more batteries arranged to supply electricity to components of the robotic tool r1, r2, r2', r2". As an example, the one or more batteries may be arranged to supply electricity to propulsion motors of the robotic tool r1, r2, r2', r2" by an amount controlled by the control arrangement 21. Moreover, the one or more batteries may be arranged to supply electricity a motor conﬁgured to power a cutting unit of the robotic tool r1, r2, r2', r2". lt is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as deﬁned by the appended claims.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components, or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions, or groups thereof.

Claims

A method (100) of providing a current position estimate of a first robotic tool (r1) of a robotic tool system (1), Wherein the robotic tool system (1) comprises the first robotic tool (r1) and one or more second robotic tools (r2, r2', r2”), and Wherein the method (100) comprises the steps of: providing current satellite-based position data of the one or more second robotic tools (r2, r2', r2”), navigating the one or more second robotic tools (r2, r2', r2”) based on the current satellite-based position data, outputting (170) a positioning request signal from the first robotic tool (r1), receiving (172) the positioning request signal in the one or more second robotic tools (r2, r2', r2”), adapting (174) the navigation of the one or more second robotic tools (r2, r2', r2”) based on the positioning request signal, outputting (110) a beacon signal/signals (Bs) from the one or more second robotic tools (r2, r2', r2”), receiving (130) the beacon signal/signals (Bs) at the first robotic tool (r1), and providing (150) a current position estimate of the first robotic tool (r1) based on the received beacon signal/signals (Bs).
The method (100) according to claim 1, Wherein the method (100) comprises the steps of: obtaining (152) a relative distance/distances between the first robotic tool (r1) and the one or more second robotic tools (r2, r2', r2”) based on the beacon signal/signals (Bs), and providing (154) the current position estimate of the first robotic tool (r1) based on the obtained relative distance/distances.
The method (100) according to claim 1 or 2, Wherein the method (100) comprises the steps of: estimating (156) an angle/angles (a1, a2, a3) of arrival of the beacon signal/signals (Bs) at the first robotic tool (r1), and providing (158) the current position estimate of the first robotic tool (r1) based on the estimated angle/angles (a1, a2, a3).
The method (100) according to any one of the preceding claims, Wherein the method (100) comprises the steps of:- providing (160) current position data of the one or more second robotic tools (r2, r2', r2”), and - providing (166) the current position estimate of the first robotic tool (r1) based on the current position data of the one or more second robotic tools (r2, r2', r2”).
The method (100) according to claim 4, wherein the method (100) comprises the steps of: - outputting (162) the current position data from the one or more second robotic tools (r2, r2', r2”), and - receiving (164) the current position data at the first robotic tool (r1).
The method (100) according to any one of the preceding claims, wherein the method (100) comprises the steps of: - providing (102) current position data of the first robotic tool (r1), - determining (104) a positioning accuracy of the current position data of the first robotic tool (r1), and - outputting (106) a beacon request signal if the positioning accuracy of the current position data is below a threshold accuracy.
The method (100) according to any one of the preceding claims, wherein the step of adapting (174) the navigation of the one or more second robotic tools (r2, r2', r2”) comprises at least one of: - stopping (175) at least one of the one or more second robotic tools (r2, r2', r2”), - navigating (176) at least one of the one or more second robotic tools (r2, r2', r2”) to an area (Ar1, Ar2, Ar3), and - restricting navigation (177) of at least one of the one or more second robotic tools (r2, r2', r2”) to an area (Ar1, Ar2, Ar3).
The method (100) according to any one of the preceding claims, wherein the robotic tool system (1) comprises two or more second robotic tools (r2, r2', r2”), and wherein the step of adapting (174) the navigation of the two or more second robotic tools (r2, r2', r2”) comprises: - navigating (178) at least one of the two or more second robotic tools (r2, r2', r2”) to obtain an angle (a4, a5) exceeding a threshold angle between two of the two or more second robotic tools (r2, r2', r2”) measured at the position of the first robotic tool (r1).The method (100) according to any one of the preceding claims, wherein the method (100) further comprises the steps of: - providing (102) current position data of the first robotic tool (r1), - determining (104) a positioning accuracy of the current position data of the first robotic tool (r1), - determining (180) an estimate accuracy of the current position estimate, and - restricting (185) the operation of the first robotic tool (r1) if the positioning accuracy is below a threshold accuracy and if the estimate accuracy is below a threshold aCCUFaCy.
The method (100) according to any one of the preceding claims, wherein the method (100) comprises the steps of: - providing (102) current position data of the first robotic tool (r1), - determining (104) a positioning accuracy of the current position data of the first robotic tool (r1), - providing (190) accuracy map data indicative of the positioning accuracy in areas
(A1, A2) operated by the robotic tool system (1).
The method (100) according to claim 10, wherein the method (100) comprises the step of: - navigating (192) one or more of the first robotic tool (r1) and the one or more second robotic tools (r2, r2', r2”) at least partially based on the accuracy map data.
A robotic tool (r2, r2', r2”) comprising: - a control arrangement (21) configured to navigate the robotic tool (r2, r2', r2”) in an area (A1, A2) based on satellite-based position data, and - an output unit (2) configured to output a beacon signal (Bs) receivable by an input unit (6) of a receiving robotic tool (r1), characterized in that the robotic tool (r2, r2', r2”) comprises an input unit (6) configured receive a positioning request signal from the receiving robotic tool (r1), and wherein the control arrangement (21) is configured to adapt the navigation of the robotic tool (r2, r2', r2”) based on the positioning request signal.
The robotic tool (r2, r2', r2”) according to claim 12, wherein the robotic tool (r2, r2', r2”) comprises a positioning arrangement (23) configured to provide current position data of the robotic tool (r2, r2', r2”), and wherein the output unit (2) is configured to output a position signal comprising the current position data.
14. 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