Tracking of surface treatment devices

Abstract

A method and system for tracking a location (Lc) of a surface treatment device (C) in a building (B). A set of local devices (Da,Db) is located in different rooms (Ra,Rb) of the building (B). Each local device comprises at least one of an optical detector (20) configured to receive an optical signal (O) from an optical beacon (10) arranged on the surface treatment device (C); and an optical beacon (10) configured to send an optical signal (O) to an optical detector (20) arranged on the surface treatment device (C). Each optical detector (20) is configured to transmit a signal (S) based on detecting that a respective optical signal (O) has been transceived between the surface treatment device (C) and a respective local device (Da) for indicating that the location (Lc) of the surface treatment device (C) corresponds to a respective room (Ra) corresponding to the respective local device (Da).

Description

[0001] Title: TRACKING OF SURFACE TREATMENT DEVICES

[0002] TECHNICAL FIELD AND BACKGROUND

[0003] The present disclosure relates to methods and systems for tracking and / or locating surface treatment devices.

[0004] Various types of surface treatment devices aim to maintain and improve the cleanliness, appearance, durabihty, and / or safety of various types of surfaces. The most prominent surface treatment activity includes surface cleaning, such as floor cleaning. Surface cleaning devices typically aim at removal of dirt, debris, stains, and / or improvement of hygiene. Examples of surface cleaning activities may include sweeping, vacuuming, mopping, scrubbing, et cetera. Wet surface cleaning involves the use of liquids on a surface, such as water, cleaning agents, and / or disinfectants. Besides surface cleaning, the treatment of surfaces may include other or further activities such as waxing, polishing, sealing, and / or refinishing.

[0005] Tracking of surface treatment devices may be implemented through wireless signals. For example, US 2019 / 0251832 Al discloses use of wireless communication networks for locating a maintenance device. However, reliance on wireless signals has inherent limitations. For example, wireless signals may sometimes penetrate through walls and floors separating different rooms within a building, thereby deteriorating the precision and reliability of tracking the location of the surface treatment device within the building. The ambiguity of which rooms have been cleaned and which remain untouched hinders the overall effectiveness of cleaning the building as it becomes difficult to distinguish the cleaning progress in all the rooms of the building. Also it may be difficult to locate a cleaning device within a building.

[0006] There is a need to further improve tracking and / or locating of surface treatment devices, e.g. improving precision with simplified tracking technology. SUMMARY

[0007] Aspects of the present disclosure relate to methods and systems for tracking the location of a surface treatment device in a building. A set of local devices is located in different rooms of the building. Each local device comprises an optical detector and / or optical beacon. For example, an optical detector of a local device may receive an optical signal from an optical beacon arranged on the surface treatment device. Alternatively, or in addition an optical beacon of a local device may send an optical signal to an optical detector arranged on the surface treatment device. Each optical detector is configured to transmit a signal based on detecting that a respective optical signal has been transceived between the surface treatment device and a respective local device provided in a respective room of the different rooms of the building. This signal may indicate that the location of the surface treatment device corresponds to the respective room.

[0008] As will be appreciated, the use of optical signals may ensure that a respective surface treatments device is only detected when there is an optical line of sight between the respective surface treatment device and a respective local device located in a respective room. Unlike wireless signals, optical signals such as infrared signals and / or visible light signals typically do not penetrate through walls, ceilings, or floors. So, the present methods and systems may avoid false signal detection in other rooms than the actual room in which the local device and treatment device are located. Accordingly, the robustness and accuracy of tracking the location of surface treatment devices may be improved. By tracking the location of the surface treatment device through the different rooms of the building, the travel path of the surface treatment device can be recorded and associated with different rooms of the building that have been cleaned and / or remain to be cleaned.

[0009] While the detection of surface treatment devices is effected by the transceiving of optical signals, the present systems and methods may use other signals to transmit the detection to other locations. By providing the optical detector with a signal generator, information associated with the detection of the optical signal can be transmitted to outside the room and / or building as a radio wave and / or electrical signal. For example, the radio wave signal can be transmitted via an antenna connected to the signal generator. Alternatively, or in addition, the electric signal can be transmitted via a power line network connected via a power supply to the signal generator. Also other modes of signal transmission can be envisaged.

[0010] By transmitting respective signals from a local device or surface treatment device comprising a respective optical detector to an external locator device (outside the room), information associated with the measurement of the respective optical signals by the respective optical detectors disposed in different rooms can be centrally processed. In this way the location of the surface treatment device can be centrally tracked through different rooms of the same building and / or different buildings. By providing a local relay, signals from the optical detectors in different rooms can be relayed over a network to a central locator device at a remote location. Advantageously, by placing a set of local relays in different buildings, location of the surface treatment device in different buildings can be tracked by a single locator device.

[0011] By providing a central locator device with a first signal indicating a respective room and a second signal indicating a general location of the respective room, the two signals can be combined at the locator device to track the location of the surface treatment device at the respective room at the general location, e.g. providing a room number in a specific building. Alternatively, or in addition, by transmitting the second signal from the surface treatment device using a cellular signal transmitter, the coverage area of a nearby cellular tower that has received the radio signal from the cellular signal transmitter can be used to indicate the general location. Advantageously, by encoding information uniquely identifying the surface treatment device in the first and / or second signal, multiple surface treatment devices can be tracked in the same room and / or general location.

[0012] By providing the locator device access to a data storage, various look-up tables that map information contained in respective signals to respective locations can be used to facilitate the tracking of the surface treatment device. For example, the look-up table can map a signal from a respective local device to a specific room and / or a specific building. In another example, the look-up table can map a property of a respective local relay and / or a respective general location to a specific building. Alternatively, or in addition, information that uniquely identifies a respective surface treatment device can be mapped to a specific building, e.g. by registering that the respective surface treatment device has been delivered to the specific building.

[0013] By storing time information about when and / or how long the surface treatment device has transceived the optical signal with the respective local device in the respective room, various further information may be derived. For example, a travel path of the surface treatment device through the different rooms of the building can be recorded and used to determine which rooms and / or how long respective rooms of the building have been cleaned and / or which rooms have been left untreated. The time information may also be compared to a threshold, e.g. to determine that a minimum amount of time was spent by a surface treatment device in a respective room. The threshold may also be dependent on a (known) size of the room, and / or previous time spent on surface treatment in the room. In one embodiment, the system is configured to generate (using the information described herein) a map of one or more rooms (or buildings), indicating for each room (or building) whether a residence time of a respective surface treatment device exceeds a respective threshold for that room (or building). By recoding the amount of light comprised in the optical signal received by the optical detector as a function of time, various patterns in the amount of light can be associated with the type of room being cleaned. For example, a pattern comprising an approximately constant amount of light can be associated with an empty room or hallway. In another example, a pattern comprising an amount of light that regularly varies between a low and high amount of light can be associated with an office room comprising cubicles.

[0014] By providing the optical beacon with a set of light sources, optical beacons disposed on different local devices, in different rooms, and / or on different surface treatment devices can be distinguished based on the modulation and / or optical characteristic of each of the set of light sources. For example, a respective one of the set of light sources may be activated in the respective room. Alternatively, or in addition, optical signal from the same light source can be modulated differently on different local devices, in different rooms, and / or on different surface treatment devices.

[0015] BRIEF DESCRIPTION OF DRAWINGS

[0016] These and other features, aspects, and advantages of the apparatus, systems and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawing wherein:

[0017] FIGs 1A and IB illustrate tracking of a surface treatment device using optical signals;

[0018] FIGs 2A and 2B illustrate various aspects of optical detectors;

[0019] FIGs 3A and 3B illustrate various aspects of locator devices;

[0020] FIGs 4A-4C illustrate various aspects of optical beacons. DESCRIPTION OF EMBODIMENTS

[0021] Terminology used for describing particular embodiments is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and / or" includes any and all combinations of one or more of the associated listed items. It will be understood that the terms "comprises" and / or "comprising" specify the presence of stated features but do not preclude the presence or addition of one or more other features. It will be further understood that when a particular step of a method is referred to as subsequent to another step, it can directly follow said other step or one or more intermediate steps may be carried out before carrying out the particular step, unless specified otherwise. Likewise it will be understood that when a connection between structures or components is described, this connection may be established directly or through intermediate structures or components unless specified otherwise.

[0022] The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the drawings, the absolute and relative sizes of systems, components, layers, and regions may be exaggerated for clarity. Embodiments may be described with reference to schematic and / or crosssection illustrations of possibly idealized embodiments and intermediate structures of the invention. In the description and drawings, like numbers refer to like elements throughout. Relative terms as well as derivatives thereof should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the system be constructed or operated in a particular orientation unless stated otherwise. FIGs 1A and IB illustrate tracking the location Lc of a surface treatment device C in a building B using a set of local devices Da,Db located in different rooms Ra,Rb of the building B. In some embodiments, e.g. as shown in FIG 1A, each local device comprises an optical detector 20 configured to receive an optical signal O from an optical beacon 10 arranged on the surface treatment device C. In other or further embodiments, e.g. as shown in FIG IB, each local device comprises an optical beacon 10 configured to send an optical signal O to an optical detector 20 arranged on the surface treatment device C. Also combinations are possible.

[0023] In one embodiment, e.g. as shown in FIG 1A, the optical beacon 10 is arranged on the surface treatment device C and the optical detector 20 is disposed in the room Ra, e.g. on a wall and / or a ceiling. In another or further embodiment, e.g. as shown in FIG IB, the optical beacon 10 is disposed in the room Ra and the optical detector 20 is arranged on the surface treatment device C. In yet another or further embodiment, a set of optical beacons 10 emitting optical signals O of different optical characteristics, e.g. light color, modulation frequency, phase and / or amplitude, is disposed over different rooms Ra,Rb separated by walls impermeable to the optical signal O, so that the optical detector 20 can distinguish different rooms from each other on the basis of the different optical characteristics of the respective optical signal O which is restricted to the respective room Ra.

[0024] In another or further embodiments, at least two optical detectors 20 are disposed in the same room to increase accuracy of detecting the surface treatment device C, e.g. in a case when an obstacle temporarily blocks an optical line of sight between a first optical detector and an optical beacon 10 arranged on the surface treatment device C, while another optical line of sight between a second optical detector and the optical beacon 10 remains unobstructed. Alternatively, or in addition, at least two optical beacons 10 are disposed in the same room and the optical detector 20 is arranged on the surface treatment device C.

[0025] In still another or further embodiments, each optical detector 20 is configured to transmit a signal S based on detecting that a respective optical signal O has been transceived between the surface treatment device C and a respective local device Da provided in a respective room Ra of the different rooms Ra,Rb of the building B for indicating that the location Lc of the surface treatment device C corresponds to the respective room Ra.

[0026] FIGs 2A and 2B illustrate an optical detector 20 comprising an optical sensor 21 configured to measure the optical signal O from the optical beacon 10. The measurement comprises, for example, detecting the optical signal O, detecting the absence of the optical signal O, and / or measuring the amplitude, frequency, modulation, and / or optical wavelength of the optical signal O.

[0027] In some embodiments, the optical detector 20 comprises a controller 22 configured to receive and process measurement information M associated with the measurement of the optical signal O by the optical sensor 21. In one embodiment, processing the measurement information M of the optical signal O by the controller comprises determining the optical wavelength, frequency, and / or amplitude of the optical signal O received by the optical sensor 21.

[0028] In other or further embodiments, the optical sensor 21 is configured to detect the optical signal O from another optical source indicating presence of the surface treatment device C in the respective room Ra, e.g. ambient light in the respective room being cleaned and / or light from a display of the surface treatment device C. For example, when someone enters the respective room Ra and the ambient light is turned on, the optical sensor 21 detects optical signal O of the ambient light. Alternatively, or in addition, the optical sensor 21 can detect no light in the respective room Ra when there is no surface treatment device C.

[0029] In yet further embodiments, the optical sensor 21 comprises a photodiode, phototransistor, photovoltaic cell, or other kind of an optoelectronic sensor capable of detecting visible, infrared, and / or ultraviolet light. Alternatively, or in addition, the optical detector 20 comprises a filter configured to pass light of the optical signal O and filter out other light.

[0030] In some embodiments, the optical detector 20 comprises a signal generator 23 coupled to the controller 22 and configured to generate an electrical signal based on the measurement information M. In one embodiment, the signal generator 23 comprises an electrical analog and / or digital driver. In another or further embodiment, the signal generator 23 is integrated into the controller 22. In yet another or further embodiment, the signal S is phase or amplitude modulated. Alternatively, the signal S is digitized.

[0031] Preferably, e.g. as shown in FIG 2A, is the signal S a non-optical wireless signal, e.g. a radio wave signal. In one embodiment, the signal generator 23 is coupled to an antenna 24 configured to wirelessly transmit the signal S. For example, the antenna 24 is configured to transmit a WiFi, Zigbee, Bluetooth, 3G, 4G, or 5G signal.

[0032] Alternatively, or in addition, e.g. as shown in FIG 2B, the signal generator 23 is coupled to a power line 27 of a power supply 25 that provides power to the optical detector 20, and is configured to superimpose the signal S on the power line 27. In one embodiment, the power line 27 of the optical detector 20 is connected via a power supply 35 to a power line 37 of the locator device 30 for transceiving the signal S. In another or further embodiment, the electrical signal is transferred to the locator device via an Ethernet cable, and / or another type of data cable.

[0033] In other or further embodiments, the optical detector 20 is a stand-alone device comprising a battery. Alternatively, or in addition, is the optical detector 20 connected to a battery of the surface treatment device C and / or to a power grid via a power plug.

[0034] In yet other or further embodiments, the optical detector 20 comprises an attachment means 26 configured to attach the optical detector 20 to parts of the different rooms Ra,Rb of the building B and / or the surface treatment device C, e.g. the optical detector 20 can be attached to a ceiling, wall, door, and / or furniture using a bolt, a screw, an adhesive, a magnet, a clip, a suction cup, or some other type of attachment. Alternatively, or in addition, the attachment means 26 is configured to engage with a light fixture, and / or a power outlet.

[0035] FIGs 3 A and 3B illustrate a locator device 30. In some embodiments, e.g. as shown in FIG 3A, the signal S is transmitted to and / or received by a locator device 30 comprising a signal receiver 31 configured to receive the signal S and a processor 32 configured to output the location Lc of the respective surface treatment device C located in the respective room Ra, based on the received signal S.

[0036] In other or further embodiments, e.g. as shown in FIG 3B, the signal S comprises information uniquely identifying the respective local device Da. In one embodiment, the signal S comprises information uniquely identifying the room Ra (and / or the location of the room within a building B) from which the respective local device Da transmitted the signal S. In another or further embodiment, the signal S comprises information uniquely identifying the surface treatment device C, e.g. a serial number, manufacturing date, building address or other kind of information unique to the respective surface treatment device C. In yet another or further embodiment, the information uniquely identifying the respective local device Da, the room Ra, and / or the respective surface treatment device C is encoded in the signal S, e.g. by means of frequency, phase and / or amplitude modulation. In some embodiments, e.g. as shown in FIG 3B, the locator device 30 is configured to receive the signal S via a local relay 3 Ir located in or near the building B. In one embodiment, the local relay 31r is configured to relay the signal S from the optical detector 20 via a network 40 to the locator device 30 at a remote location, e.g. remote from the building B. This embodiment is advantageous in situations where the locator device 30 is unable to directly receive the signal S from the optical detector 20.

[0037] In other or further embodiments, the locator device 30 is configured to receive respective signals S via respective local relays 31r, each respective local relay 3 Ir being located in or near a different building Bx,By, each building Bx having at least one room Ra provided with a respective local device Da configured to transmit a respective signal S to the respective local relay 31r. In one embodiment, the building B is determined based on a property I of the local relay 31r. For example, the local relay 31r comprises, or is coupled to, a router and the property I of the local relay 3 Ir comprises an IP address and / or a MAC address of the router.

[0038] In some embodiments, the locator device 30 is configured to receive a first signal S based on detecting that a respective optical signal O has been transceived between the surface treatment device C and a respective local device Da provided in a respective room Ra. In another or further embodiments, the locator device 30 is configured to receive a second signal Sc, separate from the first signal S indicating a general location Gx of the surface treatment device C. In one embodiment, the second signal Sc is based on a radio wave signal emitted and / or received by the surface treatment device C. In yet another or further embodiments, the locator device 30 is configured to determine, based on a combination of the first and second signals S,Sc, a combined location of the surface treatment device C being located in the respective room Ra of a specific building Bx disposed at the general location Gx. In some embodiments, the general location Gx is determined based on a coverage area of a nearby cellular tower 50 that receives the second signal Sc comprising a radio wave signal from a cellular signal transmitter Ct arranged on the surface treatment device C. For example, the locator device 30 accesses a storage 33 that stores information that associates the general location Gx, indicated by the second signal Sc, with a specific building Bx at the general location Gx. In other example, the location Lc comprises a room number and the general location Gx comprises an address of a building Bx, both of which, when combined, provide the tracked location Lc of the surface treatment device C, e.g. a specific room number in a specific building. Alternatively, or in addition, it can also be envisaged that the general location Gx is determined based on a radio wave signal received by a cellular signal receiver, e.g. transceiver, arranged on the surface treatment device from the nearby cellular tower 50. For example, the general location may be determined by identifying the cellular signal transmitter Ct and / or the general location Gx associated there with.

[0039] In another or further embodiments, the locator device 30 is configured to receive, based on the first signal S and / or based on the second signal Sc, information uniquely identifying the surface treatment device C. In one embodiment, the information comprises a serial number, date of manufacture, or other type of information unique to the respective surface treatment device C.

[0040] In some embodiments, the locator device 30 is configured to access a data storage 33, e.g. a memory and / or a database, comprising at least one look-up table. In one embodiment, the data storage 33 is accessed via the processor 32 of the locator device 30 to output the location Lc of the respective surface treatment device C. Alternatively, or in addition, the data storage 33 is integrated in the locator device 30.

[0041] In one embodiment, the at least one look-up table associates the respective local device Da with a respective room Ra and / or with a specific building Bx. For example, the locator device 30 receives the signal S from the respective local device Da that is associated with the respective room Ra and / or with the specific building Bx.

[0042] In another or further embodiment, the at least one look-up table associates a respective general location Gx with a specific building Bx. For example, the locator device 30 receives, from the cellular signal transmitter Ct, the second signal Sc comprising the respective general location Gx that is associated with the specific building Bx.

[0043] In yet another or further embodiment, the at least one look-up table associates a respective property lx of the local relay 31r with the specific building Bx. For example, the locator device 30 receives, from the respective local relay 31r, the signal S comprising a respective property lx that is associated with the specific building Bx.

[0044] In yet another or further embodiment, the at least one look-up table associates the respective surface treatment device C with the specific building Bx. For example, the locator device 30 receives, from the cellular signal transmitter Ct, the second signal Sc comprising information uniquely identifying the surface treatment device C that is associated with the specific building Bx. In other example, the locator device 30 receives, from the respective local relay 31r, the respective signal S comprising information uniquely identifying the surface treatment device C that is associated with the specific building Bx.

[0045] Preferably, the data storage 33 comprises at least one look-up table mapping the respective local device Da to the respective room Ra, and the respective surface treatment device C and / or the respective general location Gx of the surface treatment device C to a specific building Bx. Alternatively, or in addition, other combinations of one or more different look-up tables can be implemented.

[0046] In some embodiments, the locator device 30 stores time information about when and / or how long the surface treatment device C has transceived the optical signal O with the respective local device Da in the respective room Ra. In one embodiment, the local devices Da,Db and / or the surface treatment device C comprise a clock configured to store the time information. In another or further embodiment, the time information is associated with a travel path of the surface treatment device C through the different rooms Ra,Rb of the building B.

[0047] In other or further embodiments, determining whether the surface treatment device C has transceived the optical signal O with the respective local device Da comprises determining whether an amount of light comprised in the optical signal O received by the optical detector 20 of the respective local device Da is above a predefined threshold. In one embodiment, the amount of light is recorded as a function of time. In another or further embodiment, patterns in the recorded amount of light as a function of time are associated with a type of room being cleaned. For example, circular motions can be associated with a conference room having a conference table in the center of the room. In another example, comb-like movements may be associated with toilet closets.

[0048] FIGs 4A-C illustrate an optical beacon 10. In one embodiment, the optical beacon 10 comprises a single light source, e.g. as shown in FIG 4A. In another or further embodiment, the optical beacon 10 comprises a set of light sources Ila, 11b, 11c, each light source having a different optical characteristic, e.g. color (as shown in FIG 4B) and / or modulation frequency (as shown in FIG 4C), associated with a specific room Ra,Rb and / or a specific surface treatment device C.

[0049] In some embodiments, the optical beacon 10 comprises a driver 12 for driving the set of light sources 11 to generate the optical signal O. For example, the driver 12 is configured to drive a set of light sources 11 comprising a light emitting diode, a halogen lamp, a fluorescent lamp, an incandescent lamp, an infrared and / or an ultraviolet light source. In other or further embodiments, different light sources Ila, 11b, 11c having a different optical characteristic are driven on different optical beacons and / or the same light source is modulated differently on different optical beacons. In yet other or further embodiments, the optical beacon 10 is integrated in a surface treatment device C and / or the set of light sources 11 comprises an interface display and / or optical indicator of a surface treatment device C, e.g. an on / off light.

[0050] In some embodiments, the method is used in a system 100 for tracking location Lc of a surface treatment device C in a building B. In one embodiment, the system 100 comprises a set of local devices Da,Db located in different rooms Ra,Rb of the building B. In another or further embodiment, each local device comprises an optical detector 20 configured to receive an optical signal O from an optical beacon 10 arranged on the surface treatment device C. In yet another or further embodiment, each local device comprises an optical beacon 10 configured to send an optical signal O to an optical detector 20 arranged on the surface treatment device C. In other or further embodiments, each optical detector 20 is configured to transmit a signal S based on detecting that a respective optical signal O has been transceived between the surface treatment device C and a respective local device Da provided in a respective room Ra of the different rooms Ra,Rb of the building B for indicating that the location Lc of the surface treatment device C corresponds to the respective room Ra.

[0051] For the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. It will be appreciated that the present disclosure may provide various benefits of improved tracking of a surface treatment device in a building, and in particular the reliable localization of the surface treatment device to a specific room. Advantages may be achieved for various types of devices used for surface treatment, and especially floor cleaning device. For example, the surface treatment device may be a walk -behind device, a ride- on device, and / or an autonomous device such as a surface treatment robot. Alternatively, also hand-held surface treatment devices could be used. The surface treatment may comprise wet surface treatment including mopping, steaming, jet cleaning, disinfecting, sanitizing, and / or waxing of the surface. Alternatively, or in addition, the surface treatment may comprise dry surface treatment such as sweeping, polishing, refinishing, sealing, and / or vacuum cleaning. By reliably tracking the location of a surface treatment device to a specific room, various advantages may be achieved such as tracking the time spent by the device in a respective room, and (indirectly) the time spent on surface treatment in said room. By placing the optical detector or beacon directly on the surface treatment device, and in a specific room, it can be ensured that this device is / was present in that room. The optical detector and / or beacon as described herein could also be placed on other (mobile) devices used in the process of surface treatment, such as a trolley. However, may be less preferably since the location of the trolley may deviate from the location where the actual surface treatment takes place. For example, surface treatment may take place in a room, while the trolley is left in an adjacent hallway.

[0052] In interpreting the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or acts than those listed in a given claim; the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements; any reference signs in the claims do not limit their scope; several "means" may be represented by the same or different item(s) or implemented structure or function; any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise.

Claims

CLAIMS1. A method for tracking a location (Lc) of a surface treatment device (C) in a building (B), the method comprising providing a set of local devices (Da,Db) located in different rooms (Ra,Rb) of the building (B), each local device comprising at least one of an optical detector (20) configured to receive an optical signal (O) from an optical beacon (10) arranged on the surface treatment device (C), and an optical beacon (10) configured to send an optical signal (O) to an optical detector (20) arranged on the surface treatment device (C); wherein each optical detector (20) is configured to transmit a signal (S) based on detecting that a respective optical signal (O) has been transceived between the surface treatment device (C) and a respective local device (Da) provided in a respective room (Ra) of the different rooms (Ra,Rb) of the building (B) for indicating that the location (Lc) of the surface treatment device (C) corresponds to the respective room (Ra).

2. The method according to the preceding claim, wherein the optical detector (20) comprises an optical sensor (21) configured to measure an optical signal (O) from the optical beacon (10); a controller (22) configured to receive and process measurement information (M) associated with the measuring of the optical signal (O) by the optical sensor (21); a signal generator (23) coupled to the controller (22) and configured to generate an electrical signal based on the measurementinformation (M).

3. The method according to the preceding claim, wherein the signal generator (23) is coupled to an antenna (24) configured to wirelessly transmit the signal (S).

4. The method according to any of the two preceding claims, wherein the signal generator (23) is coupled to a power line (27) supplying power to the optical detector (20), wherein the signal generator (23) is configured to superimpose the signal (S) onto the power hne (27).

5. The method according to any of the preceding claims, wherein the signal (S) is transmitted to a locator device (30) comprising a signal receiver (31) configured to receive the signal (S); and a processor (32) configured to output the location (Lc) of the respective surface treatment device (C) located in the respective room (Ra), based on the received signal (S).

6. The method according to any of the preceding claims, wherein the locator device (30) is configured to receive the signal (S) via a local relay (31r) located in or near the building (B), wherein the local relay (31r) is configured to relay the signal (S) from the optical detector (20) over a network (40) to the locator device (30) at a remote location.

7. The method according to the two preceding claims, wherein the locator device (30) is configured to receive respective signals (S) via respective local relays (3 Ir), each respective local relay (3 Ir) located at or near a different building (Bx,By), each building (Bx) having at least one room (Ra) provided with a respective local device (Da) configured to transmit a respective signal(S) to the respective local relay (31r).

8. The method according to any of the three preceding claims, wherein the locator device (30) is configured to receive a first signal (S) based on detecting that a respective optical signal (O) has been transceived between the surface treatment device (C) and a respective local device (Da) provided in a respective room (Ra); receive a second signal (Sc), separate from the first signal (S), indicating a general location (Gx) of the surface treatment device (C), wherein the second signal (Sc) is based on a radio wave signal emitted and / or received by the surface treatment device (C); and determine, based on a combination of the first and second signals (S,Sc), a combined location of the surface treatment device (C) being located in the respective room (Ra) of a specific building (Bx) disposed at the general location (Gx).

9. The method according to the preceding claim, wherein the second signal (Sc) is a radio signal, wherein the general location (Gx) is determined based on a coverage area of a nearby cellular tower (50) receiving the radio signal from a cellular signal transmitter (Ct) arranged on the surface treatment device (C) and / or transmitting the radio signal to a cellular signal receiver arranged on the surface treatment device (C).

10. The method according to any of the two preceding claims, wherein the locator device (30) is configured to receive, based on the first signal (S) and / or based on the second signal (Sc), information uniquely identifying the surface treatment device (C).

11. The method according to claim 5, or any claim dependent thereon, wherein the locator device (30) is configured to access a data storage (33) comprising a look-up table mapping at least one of the respective local device (Da) to the respective room (Ra); the respective local device (Da) to the building (B) in which the respective local device (Da) is located; a respective general location (Gx) to a specific building (Bx) at the respective general location (Gx); a respective property (lx) of a local relay (31r) to a specific building (Bx) housing said local relay (3 Ir); a respective surface treatment device (C) to a specific building (Bx) at which the surface treatment device (C) is located; wherein the locator device (30) is configured to output the location (Lc) of the respective surface treatment device (C) based on a combination of one or more received signals (S,Sc) and information accessed from the look-up table.

12. The method according to any of the preceding claims, wherein the locator device (30) stores time information about when and / or how long the surface treatment device (C) has transceived the optical signal (O) with the respective local device (Da) in the respective room (Ra).

13. The method according to the preceding claim, comprising comparing the time information indicating how long the surface treatment device (C) has transceived the optical signal (O) with the respective local device (Da) in the respective room (Ra) to a predetermined threshold time; and determining, based on the comparing, whether the surface treatment device (C) has spent sufficient time for surface treatment of therespective room (Ra).

14. The method according to any of the preceding claims, wherein the optical beacon (10) comprises a set of light sources (11) and a driver (12) for driving the set of light sources (11) to generate the optical signal (O), wherein different light sources (Ila, 11b, 11c) having a different optical characteristic are driven on different optical beacons and / or wherein the same light source is modulated differently on different optical beacons.

15. A system (100) for tracking a location (Lc) of a surface treatment device (C) in a building (B), the system (100) comprising a set of local devices (Da,Db) located in different rooms (Ra,Rb) of the building (B), each local device comprising at least one of an optical detector (20) configured to receive an optical signal (O) from an optical beacon (10) arranged on the surface treatment device (C), and an optical beacon (10) configured to send an optical signal (O) to an optical detector (20) arranged on the surface treatment device (C); wherein each optical detector (20) is configured to transmit a signal (S) based on detecting that a respective optical signal (O) has been transceived between the surface treatment device (C) and a respective local device (Da) provided in a respective room (Ra) of the different rooms (Ra,Rb) of the building (B) for indicating that the location (Lc) of the surface treatment device (C) corresponds to the respective room (Ra).

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