EP3912005A1 - Robotic tool - Google Patents

Robotic tool

Info

Publication number
EP3912005A1
EP3912005A1 EP20700770.9A EP20700770A EP3912005A1 EP 3912005 A1 EP3912005 A1 EP 3912005A1 EP 20700770 A EP20700770 A EP 20700770A EP 3912005 A1 EP3912005 A1 EP 3912005A1
Authority
EP
European Patent Office
Prior art keywords
self
robotic tool
signal
robotic
bursts
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP20700770.9A
Other languages
German (de)
French (fr)
Inventor
Marcus LILJEDAHL
Jonas RANGSJÖ
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Husqvarna AB
Original Assignee
Husqvarna AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Husqvarna AB filed Critical Husqvarna AB
Publication of EP3912005A1 publication Critical patent/EP3912005A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
    • G05D1/40—Control within particular dimensions
    • G05D1/43—Control of position or course in two dimensions [2D]
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D1/00—Control of position, course, altitude or attitude of land, water, air or space vehicles, e.g. using automatic pilots
    • G05D1/02—Control of position or course in two dimensions
    • G05D1/021—Control of position or course in two dimensions specially adapted to land vehicles
    • G05D1/0259—Control of position or course in two dimensions specially adapted to land vehicles using magnetic or electromagnetic means
    • G05D1/0265—Control of position or course in two dimensions specially adapted to land vehicles using magnetic or electromagnetic means using buried wires
    • A—HUMAN NECESSITIES
    • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
    • A01D—HARVESTING; MOWING
    • A01D34/00—Mowers; Mowing apparatus of harvesters
    • A01D34/006—Control or measuring arrangements
    • A01D34/008—Control or measuring arrangements for automated or remotely controlled operation
    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
    • G05D2111/00—Details of signals used for control of position, course, altitude or attitude of land, water, air or space vehicles
    • G05D2111/30—Radio signals
    • G05D2111/36—Radio signals generated or reflected by cables or wires carrying current, e.g. boundary wires or leaky feeder cables

Definitions

  • the present disclosure relates to a self-propelled robotic tool comprising a work implement, a driving arrangement for moving the robotic work tool, a control device for controlling the driving arrangement, and an acquisition device, configured to record a signal transmitted in bursts by a boundary wire loop, wherein the control device is configured to determine whether the robotic work tool is located within an area defined by the boundary wire loop based on the recorded signal.
  • Fig 3 illustrates an example of burst with certain signatures or patterns.
  • the method may begin with clearing 45 the buffer 41 or memory.
  • the system waits 47 an estimated period time P est , and thereafter samples 49 data input from the coil 23.
  • the sampled data is added 51 to the buffer 41.
  • adding is here meant that the received signal is added to corresponding data from previous pulses such that the value at a time t, v t is added to the corresponding value of previous pulses v t -p+v t -2 P +... etc.
  • the sum in the buffer thus corresponds to an average of pulses received since the last clear event, even if not divided by the number of pulses.
  • other and different FIR- and MR filter configurations are possible.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • General Physics & Mathematics (AREA)
  • Automation & Control Theory (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Environmental Sciences (AREA)
  • Electromagnetism (AREA)
  • Manipulator (AREA)

Abstract

The present disclosure relates to a self-propelled robotic tool (1) comprising a work implement (3), a driving arrangement (5, 7, 9, 11) for moving the robotic work tool, a control device (13) for controlling the driving arrangement, and an acquisition device (23, 25), configured to record a signal (27; 31) transmitted in bursts by a boundary wire loop (19), wherein the control device is configured to determine whether the robotic work tool is located within an area (17) defined by the boundary wire loop based on the recorded signal. There is provided a digital signal processor (39) which is configured to provide an output corresponding to an average of a plurality of recorded transmitted signal bursts, wherein the control device (13) is configured to determine whether the robotic tool (1) is located within said area (17) at least partly based on said output.

Description

ROBOTIC TOOL
Technical field
The present disclosure relates to a self-propelled robotic tool comprising a work implement, a driving arrangement for moving the robotic work tool, a control device for controlling the driving arrangement, and an acquisition device, configured to record a signal transmitted in bursts by a boundary wire loop, wherein the control device is configured to determine whether the robotic work tool is located within an area defined by the boundary wire loop based on the recorded signal.
Further, a corresponding method for controlling a self-propelled robotic tool is considered.
Background
Such a self-propelled robotic tool is disclosed for instance in EP-2741160-A1 , where a recorded signal is correlated with a reference signal, or the like, in order to determine whether the robotic work tool is located within the area in question.
One general problem associated with tools of this type is how to increase the reliability in determining whether the robotic tool remains located within the area defined by the boundary wire loop.
Summary
One object of the present disclosure is therefore to provide a self-propelled robotic tool which determines with an increased reliability whether the tool is located within a work area.
This object is achieved by means of a self-propelled robotic tool as defined in claim 1. More particularly, in a self-propelled robotic tool of the initially mentioned kind, a digital signal processor is provided which is configured to provide an output corresponding to an average of a plurality of recorded transmitted signal bursts. The control device is configured to determine whether the robotic tool is located within said area at least partly based on said output. This allows the determining of whether the robotic tool remains located within the area in question in a more reliable manner in particular to deal with noisy conditions. The output may correspond to an average of a sequence of bursts repeated with an estimated period time (P).
In this average burst, the order of flanks or other pulse characteristic may then be determined and compared to a reference. Alternatively, the determined average may be correlated with a reference pattern.
Typically, the average may be made up from between 2 and 20 of the most recently received pulses.
The estimated period time may be determined using a recursive algorithm.
Typically, the self-propelled robotic tool may be a robotic lawn mower.
It is possible to prepare in parallel two or more averages, based on different pluralities of recorded transmitted signal bursts.
The present disclosure further considers a corresponding method comprising the steps carried out in a self-propelled robotic tool as defined above.
Brief description of the drawings
Fig 1 illustrates schematically a self-propelled robotic tool operating in a work area.
Fig 2 schematically illustrates system units of the self-propelled robotic tool in fig 1.
Fig 3 illustrates an example of burst with certain signatures or patterns.
Fig 4 shows an example of a signal with burst having specific flank orders.
Fig 5 illustrates digital signal processing using a number of successive bursts.
Fig 6 illustrates schematically units in a system carrying out a detection method and fig 7 illustrates an example flowchart of such a detection method.
Detailed description
The present disclosure relates generally to self-propelled robotic work tools, of the kind disclosed for instance in EP-2741160-A1 , where a robotic mower for cutting lawns is shown as an example. Such a mower is shown schematically in figs 1 and 2 where a mower 1 has a cutting implement 3, e.g. a rotating knife, and wheels 5, 7 typically driven by electric motors 9, 11. There may also be provided non-driven, e.g. swiveling wheels, and various other wheel configurations are possible. The steering of the robotic work tool is carried out by controlling the driving motors 9,
11 by means of a control unit 13, of. fig 2. A battery arrangement 15 powers the motors 9, 11 as well as the control unit 13.
By controlling the motors 9, 11 , the control unit 13 moves the robotic work tool 1 over a work area 17, typically a lawn. A boundary wire 19, which may typically be buried a few centimeters deep in the ground, defines the work area 17, the boundary wire 19 forming a loop, which is typically closed at a transmission unit 21 , transmitting a signal on the boundary wire 19. The ends of the boundary wire 19 are typically connected to the transmission unit 21 which may be integrated with a charging station that can be used to intermittently charge the battery arrangement 15.
The transmission unit 21 thus feeds an electric signal to the boundary wire 19 that operates as a form of antenna, radiating an electromagnetic signal which the robotic work tool 1 can pick up using one or more coils. Based on the signal, the robotic work tool can be controlled, typically making sure that the robotic work tool remains within the work area 17. In the aforementioned document, the transmitted signal comprises bursts of signals with predetermined patterns and separated by pauses. Within the bursts, the signal switches between high and low states, where the duration of the high states is different from the duration of the low states within a burst.
The electromagnetic signals transmitted by the boundary wire 19 are thus picked up by two or more coils 23, 25 connected to the control unit 13 in the robotic work tool 1. The picked-up signal may be more or less equivalent to the first order derivative of the current fed to the boundary wire 19, and therefore also the signals fed to the control unit 13 have a distinguishable pattern. If all of the two or more coils 23, 25 are located inside the work area 17 defined by the boundary wire 19, the patterns will be similar, and any disturbances will also affect both signals similarly. When the robotic tool 1 is about to move outside the work area, however, one of the coils 23 will be located outside and another one 25 inside the work area 17. At this point, the signals acquired by the first and second coils 23, 25 will become diametrically different.
It has also been suggested to use a transmission unit 21 , transmitting a signal 27 with bursts having a predetermined pattern 29 or signature as illustrated in fig 3.
When receiving a signal, using one single coil, the self-propelled robotic tool may correlate the received signal with an internally stored template. As long as the correlation between the received signal’s pattern and the template is high, the self- propelled robotic tool is considered to remain within the work area 17. When the self- propelled robotic tool moves outside this area however, the phase of the received signal reverses and the correlation drops, which can be determined by the control unit 13.
Another example of a signal transmitted via a boundary wire is described in EP- 1512053-A1. In that example, a signal 31 with bursts comprising a set of pulses with positive and negative flanks (voltage) having a predetermined order is transmitted, as illustrated in fig 4. It may be determined, on the receiving side, for instance that a burst beginning with a positive pulse with a certain length is received, followed by a negative pulse of a certain length. This may be sufficient to determine whether or not the self-propelled robotic tool remains within the work area. Bursts are repeated with a period time P or offset time. The order of flanks is one example of a pulse characteristic, other examples include lengths of pulses in a burst and/or delays therebetween.
In both the initially described schemes however, noise and interference may make the detection difficult. This has been addressed by using a high enough burst amplitude such that correct detecting takes place. That however may lead to high power consumption and, more importantly, to excessive interference disturbing other systems nearby.
In the present disclosure, correct detection is instead achieved by using a digital signal processor which provides an output based on an average of a plurality of recorded transmitted signal bursts. The control device is configured to determine whether the robotic tool is located within said area at least partly based on said output.
An example of this is illustrated in fig 5 where a received signal 33 corresponding to the transmitted signal of fig 4 is shown. As illustrated, the received signal may be very noisy, and it may be difficult to assess e.g. the order of flanks, positive-negative- positive based on an individual burst 35. However, by using a digital signal processor it is possible to superpose a plurality of such individual burst to form a sum corre sponding to an average burst 37 thereof. In this signal e.g. the order of flanks can be detected more easily. By a burst is here generally meant a varying signal that lasts for a certain amount of time.
As mentioned, the averaging may typically be made up from between 2 and 20 of the most recently received bursts. However, it is also possible to provide parallel averages based on different numbers of recent bursts, such as for instance 3 and 15 pulses. A small number of pulses will give an average that changes more quickly, while a greater number is more stable. Which one to use may be determined by noise conditions or other quality parameters. It is also possible to make decisions based on comparison of averages based on different numbers of bursts.
Fig 6 illustrates schematically units in a system carrying out a detection method and fig 7 illustrates an example flowchart of such a detection method. The method may be carried out by a digital signal processor 39, DSP, in the control unit 13. By a DSP is here meant circuitry carrying out digital operations on data although other hardware configurations are conceivable. Further, a buffer 41 and a timing unit 43 may be provided, which are shown as individual units although they may be integrated for instance in the DSP 39.
With reference to fig 7, the method may begin with clearing 45 the buffer 41 or memory. The system waits 47 an estimated period time Pest, and thereafter samples 49 data input from the coil 23. The sampled data is added 51 to the buffer 41. By adding is here meant that the received signal is added to corresponding data from previous pulses such that the value at a time t, vt is added to the corresponding value of previous pulses vt-p+vt-2P+... etc. The sum in the buffer thus corresponds to an average of pulses received since the last clear event, even if not divided by the number of pulses. Also, other and different FIR- and MR filter configurations are possible.
Detection 53 is then done on the data in the buffer, whether by testing the order of flanks or other pulse characteristic, or carrying out a correlation procedure. If the detection is considered successful 55, the process may go on to report the condition (inside/outside work area) to other functions in the control unit 13. If, however, the accumulated data is insufficient to carry out detection, the process in the DSP 39 may instead wait another period P, sample a new burst and add to the buffer 49, 51 , and again attempt to detect 53 the condition. Once a condition has been reported 57, it may be useful to update the estimated period time. This may be done by adjusting the previously estimated period Pest which was used during the last accumulation as a linear combination with the period time Pdet that can be determined from the last accumulated bursts, e.g. such that the new estimated period time Pestnew can be defined as: Pestnew= 0.9*Pest+0.1 *Pdet .
This provides a recursive algorithm that adapts the detection to the transmitted signal and may be further developed using Kalman filters and the like.
The present disclosure is not limited to the above-described examples and may be varied and altered in different ways within the scope of the appended claims.
For instance, even if the transmitted signals have been shown as short bursts interleaved with long pauses, the burst may be as long as the period time such as the signal appears to be transmitted continuously.

Claims

1. A self-propelled robotic tool (1 ) comprising a work implement (3), a driving arrangement (5, 7, 9, 11 ) for moving the robotic work tool, a control device (13) for controlling the driving arrangement, and an acquisition device (23, 25), configured to record a signal (27; 31 ) transmitted in bursts by a boundary wire loop (19), wherein the control device is configured to determine whether the robotic work tool is located within an area (17) defined by the boundary wire loop based on the recorded signal, characterized by a digital signal processor (39) which is configured to provide an output corresponding to an average of a plurality of recorded
transmitted signal bursts, wherein the control device (13) is configured to determine whether the robotic tool (1 ) is located within said area (17) at least partly based on said output.
2. Self-propelled robotic tool according to claim 1 , wherein the output corresponds to an average of a sequence of pulses repeated with an estimated period time (P).
3. Self-propelled robotic tool according to claim 2, wherein a pulse characteristic in the determined average is compared to pulse characteristic reference.
4. Self-propelled robotic tool according to claim 2, wherein the determined average is correlated with a reference pattern.
5. Self-propelled robotic tool according to any of claims 2 to 4, wherein the average is made up from between 2 and 20 of the most recently received pulses.
6. Self-propelled robotic tool according to any of claims 2 to 5, wherein the estimated period time is determined using a recursive algorithm.
7. Self-propelled robotic tool according to any of the preceding claims, wherein the self-propelled robotic tool is a lawn mower.
8. Self-propelled robotic tool according to any of the preceding claims, wherein in parallel two or more averages, based on different pluralities of recorded transmitted signal bursts, are prepared.
9. A method for controlling a self-propelled robotic tool comprising a work implement, a driving arrangement for moving the robotic work tool, a control device for controlling the driving arrangement, and an acquisition device, configured to record a signal transmitted in bursts by a boundary wire loop, wherein the control device determines whether the robotic work tool is located within an area defined by the boundary wire loop based on the recorded signal characterized by a providing an output corresponding to an average of a plurality of recorded transmitted signal bursts, and determining whether the robotic tool is located within said area at least partly based on said output.
EP20700770.9A 2019-01-15 2020-01-09 Robotic tool Withdrawn EP3912005A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE1950041A SE542918C2 (en) 2019-01-15 2019-01-15 Robotic tool with boundary wire loop
PCT/EP2020/050356 WO2020148138A1 (en) 2019-01-15 2020-01-09 Robotic tool

Publications (1)

Publication Number Publication Date
EP3912005A1 true EP3912005A1 (en) 2021-11-24

Family

ID=69167799

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20700770.9A Withdrawn EP3912005A1 (en) 2019-01-15 2020-01-09 Robotic tool

Country Status (3)

Country Link
EP (1) EP3912005A1 (en)
SE (1) SE542918C2 (en)
WO (1) WO2020148138A1 (en)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2022126364A1 (en) * 2020-12-15 2022-06-23 Globe (jiangsu) Co., Ltd. Signal interference rejection method and apparatus
US12296694B2 (en) 2021-03-10 2025-05-13 Techtronic Cordless Gp Lawnmowers
US12443180B2 (en) 2021-11-10 2025-10-14 Techtronic Cordless Gp Robotic lawn mowers
AU2023200381A1 (en) 2022-01-31 2023-08-17 Techtronic Cordless Gp Robotic garden tool
EP4270138A1 (en) 2022-04-28 2023-11-01 Techtronic Cordless GP Creation of a virtual boundary for a robotic garden tool
US12472611B2 (en) 2022-05-31 2025-11-18 Techtronic Cordless Gp Peg driver
EP4310621B1 (en) 2022-07-19 2025-02-12 Techtronic Cordless GP Display for controlling robotic tool
AU2023206123A1 (en) 2022-07-29 2024-02-15 Techtronic Cordless Gp Generation of a cryptography key for a robotic garden tool

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2679083B1 (en) * 2012-06-27 2015-08-05 Fabrizio Bernini Apparatus for cutting grass

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE0201739D0 (en) 2002-06-07 2002-06-07 Electrolux Ab Electronic demarcation system
EP2741160B1 (en) 2012-12-07 2016-10-12 Viking GmbH Method for controlling a self-propelled lawn mower

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2679083B1 (en) * 2012-06-27 2015-08-05 Fabrizio Bernini Apparatus for cutting grass

Also Published As

Publication number Publication date
WO2020148138A1 (en) 2020-07-23
SE1950041A1 (en) 2020-07-16
SE542918C2 (en) 2020-09-15

Similar Documents

Publication Publication Date Title
EP3912005A1 (en) Robotic tool
CN100374963C (en) electronic range system
EP1512054B1 (en) Electronic directing system
CN106168484B (en) Borderline pulse signal identification system and method and intelligent mowing system
EP3376329B1 (en) Automatic working system and control method therefor, and automatic walking device
EP3614825B1 (en) Improved reception of frequency spectra on the receiver side
US10459452B2 (en) Method for detecting a working area of an autonomous working device, and a working device
EP3100126B1 (en) Robotic working tool system with a boundary wire
EP2382516B1 (en) Method and system for recognizing the working range of a mobile tool
EP3614824B1 (en) Robotic lawnmower system with adaptive signal transmission
EP3779508B1 (en) Re-directing radar transmission power for interference mitigation
CN113156396A (en) Method and device for optimizing influence of interference source on laser radar
CN111580175A (en) Infrared signal processing method and device and household appliance
CN108631452B (en) Laser charging protection method and device
CN114510026B (en) Boundary line signal detection method and automatic walking equipment
DE102009045429A1 (en) Method and device for locating an object by reflection detection of wave pulses
CN114952936A (en) Signal anti-jamming method, equipment and medium applied to robot boundary system
CN223501159U (en) Anti-jamming radar detection device
CN116547621B (en) Signal interference suppression method and device
CN116541691B (en) Method for anti-interference detection of boundary line signals for automatic walking equipment
US20060208705A1 (en) Method & apparatus to ensure that saturation of the battery does not occur during resonant finding phase as well as implementation methods to quickly find resonance
CN114637281A (en) Automatic walking equipment and boundary signal detection method thereof
JP2000275335A (en) Target tracking guidance device, target tracking flight device, and target tracking guidance method

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: UNKNOWN

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20210715

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

17Q First examination report despatched

Effective date: 20220727

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20221207