WO2011064332A1

WO2011064332A1 - A navigation system and method for navigation using location signals from light sources

Info

Publication number: WO2011064332A1
Application number: PCT/EP2010/068311
Authority: WO
Inventors: Thao Bui; Siegfried Heckmann; Josef Otte; Ludwig Schwoerer
Original assignee: HOCHSCHULE BOCHUM
Current assignee: HOCHSCHULE BOCHUM
Priority date: 2009-11-27
Filing date: 2010-11-26
Publication date: 2011-06-03
Anticipated expiration: 2012-05-27
Also published as: WO2011064342A1; GB0920777D0; GB2475713A

Abstract

The present disclosure teaches a navigation/location system comprising at least one first light source (110a, 110b,..., 110n) adapted to generate at least one of a first location signal (130) using a satellite navigation protocol. The present disclosure further teaches a navigation/location method (300). The method (300) comprises a generating of at least one first location signal (130) from at least a first light source (110a, 110b,..., 110n), transmitting the at least one first location signal (130) using the satellite navigation protocol. The at least one first location signal (130) is received and a location (180) is determined using the received at least one first location signal (130). The present disclosure further teaches a navigation/location device (200). The navigation/location device (200) comprises a location signal receiver (210), a memory (220) and a processor (230). The location signal receiver (210) receives at least one first location signal (130) from at least one first light source. The memory stores a map file (160) and the processor (230) determines the location (180).

Description

Title:

A navigation system and method for navigation using location signals from light sources Field of the Invention

[0001] The field of the invention relates to a navigation location system and method for navigation or location using location signals generated from lights sources.

Background to the Invention

(0002] The use of light emitting diodes for general lighting has been enabled by the development of white LEDs and also the fall in price. LEDs are able to illuminate an area at much lower power consumption man traditional light bulbs. The lower power consumption of LEDs offer a contribution to reducing global wanning.

[0003] LEDs have the further advantage mat they can be used to transmit information to receiver devices within range. This is termed Visual Light Communication (VLC) and has been discussed in US Patent Application Publication No US 2009/157309 (Won et al) with respect to a navigation system. Won et al have developed a method and device for exchanging messages in a VLC navigation system. A terminal mat wants to implement the navigation service transmits a registration request to a map server. The map server transmits a map request message to the terminal. The terminal transmits a map request message including information about a destination to the map server, which then transmits a map response message including information about a path to the destination to the terminal. The terminal is able to display the map information and the path.

[0004] US Patent Application Publication No US 2009/0171571 (Son et al) teaches a system and method for providing an in-building navigation system using VLC. Transmitters control a plurality of lamp modules to generate visible light signals in a combination of different wavelengths as information for a navigation function. A mobile terminal receives the visible lights signals from the plurality of lamp modules that illuminate an area in which the mobile terminal is located. Location information about a current location of the mobile terminal is acquired through the visible light signals received from the plurality of lamp modules and navigation information including information that matches the location information to map information is displayed on the mobile terminal

[0005] It has been proposed to use wireless LAN as an in-building navigation system in the past However, the movement of a person within the building will affect the field distribution and thus the reliability of the navigation system.

[0006] The present disclosure teaches a navigation/location system. The navigation/location system comprises at least one first light source mat is adapted to generate at least one first location signal using a satellite navigation protocol.

[0007] The term "satellite navigation protocol" as used in the present disclosure means a protocol through which a satellite navigation system describes a position of an object Examples of such satellite navigation systems include, but are not limited to, the global positioning system (GPS), the Galileo system or the Glonass system. The satellite navigation protocol includes, but is not limited to, the NMEA protocol as known in the art

[0008] The present disclosure will be explained using the example of the GPS system as the satellite navigation system with the NMEA protocol as the satellite navigation protocol. Effort for generating the first location signals is reduced if the known satellite navigation protocol is used. This allows the integration of the navigation location system of the discussion with the satellite navigation system. Concurrent use of the satellite navigation system and the navigation/location system of the present disclosure is thereby possible.

[0009] The navigation/location system may further comprise at least one second light source. The at least one first location signal may be generated using a pair of module- tion frequencies. The second light sources may provide at least second location signal at a second pair of modulation frequencies. The first pair of modulation frequencies and the second pair of modulation frequencies help in preventing an interference of at least one first location signal and the at least one second location signal.

[00010] The present disclosure further teaches a navigation location method. The navigation/location method comprises a step of generating at least one first location signal from at least one first light source. The method comprises a transmitting of at least one first location signal using the satellite navigation protocol. The method also comprises a deter- mining of a location using the received at least one first location signal.

[00011] The present disclosure further relates to a navigation/location device. The navigation/location device comprises a location signal receiver, a memory and a processor. The location receiver receives at least one first location signal from at least one first light source. The memory stores a map file and may store more than one map file. The processor determines a location.

[00012] The navigation/location device may further be adapted to receive at least one second location signal from at least one second light source. The navigation/location device may further comprise a receiver for signals from a satellite navigation system. The navigation/location device may further comprise a transmitter for transmitting the location to a receiver of the navigation/location system.

[00013] Use of the navigation/location device of the present disclosure and/or the navigation/location system of the present disclosure is conceivable for navigation or location. The navigation and/or location may be used by a person, a vehicle, a valuable movable object, rescue services, persons, pedestrians, tourists, visitors in a building such as museum or exhibition hall, a geriatric care centre, a hospital, a hotel, a road tunnel, a railway tunnel, a sewage tunnel or a mine. The present disclosure is of interest to situations and circumstances wherein the satellite navigation system is not reliably available for navigating and locating. [00014] The present disclosure may be used for a person to navigate himself or herself. An object, such as a truck or movable medical or nursing equipment may be navigated, for example, in a warehouse. The teachings of the present disclosure may further be used to locate a person or any moving objects, such as the truck or a cleaning unit

Description of the Drawings

Fig. 1 shows a navigation/location system.

Fig. 2 shows a navigation/location device.

Fig. 3 shows a method for navigation or location.

Detailed Description of the Invention

[00015] The invention will now be described on the basis of the drawings. It will be understood mat the embodiments and aspects described herein are only examples and do not limit the protective scope of the claims in any way. The invention is defined by the claims and their equivalents. It will also be understood mat features of one aspect can be combined with features of a different aspect [00016] Fig. 1 shows an example of a navigation/location system 100 with a plurality of light sources 110a, 110b, 1 lOn (collectively numbered as 110) and a plurality of second light sources 120a, 120b, ...„ 120n (collectively numbered 120). The first light sources 110 and the second light sources 120 are in one aspect of the invention white LEDs. It will be appreciated that the first light sources 110 and/or the second light sources 120 can also be coloured LEDs or other types of light sources that generate light that can be modulated to transmit a data signal. One example would be laser light

[00017] The first light sources 110 and/or and the second light sources 120 are typically placed on the ceiling of a room from which area the first light sources 110 and the second light sources 120 are visible or detectable throughout the room. It is not excluded mat the first light sources 110 and the second light sources 120 are placed at other locations in a room, for example on pillars or next to power supplies. The first light sources 110 and the second light sources 120 could also form part of the emergency lighting system. An example tor the first light sources 110 and the second light sources 120 includes, but is not limited to, is Philips Luxion having a colour temperature of 6400K and a nominal power of 3W. It will be noted that the first light sources 110 and the second light sources 120 could also be a combination of visible light and infrared light

[00018] The invisible light may be in an infrared spectrum or an ultraviolet spectrum if the first light sources 110 and the second light sources 120 are emitting invisible light It is of interest to provide the first light source 110 and/or the second light source 120 emit- ting infrared light, as photodiodes are typically very sensitive to infrared light Hence using LEDs emitting in the infrared spectrum will considerably reduce power needed for receiving information pertaining to a location 180 of the first light source 110 and/or the second light source 120. It will be appreciated that using the first light sources 110 and/or the second light sources emitting invisible light will also work in a dark environment, for exam- pie, in situations where a lighting of a building is switched off, such as during night hours.

[00019] It is possible to use the first light sources 110 without the second light sources 120. In such a case the second light sources as shown in Figure 1 are omitted. [00020] The first light sources 110 provide the location signals 130 using a satellite navigation protocol. It will be appreciated that the present disclosure is adapted for any type of satellite navigation protocol. The present disclosure uses "faked" satellite navigation positional data as the satellite navigation protocol. The first light sources 110 and/or the second light sources 120 emit signals using the satellite navigation protocol. It will be noted that providing both the first light sources 110 and the second light sources 120 may increase costs of the navigation location system 100 but provide an improved spatial resolution of the position 180 of the navigation unit 200 as the first location signal 130 and the second location signal 140 may be used for determining the present location of the navigation unit 200.

[00021] A map transmission unit ISO can be provided for the navigation location system 100. The map transmission unit 150 stores one or more map files 160 containing the location data 165. The location data 165 provides the location of each one of the first light sources 110 and/or the second light sources 120 (if these are present). The map files 160 are typically stored as JPEG data files, but this is not limiting of the navigation/location system 00 of the present disclosure.

[00022] The first light sources 110 and the second light sources 120 each have a programmable memory 170 (with corresponding data entry interlace 173). The programmable memory 170 stores the location 180 of the corresponding first light source 110 and/or the corresponding second light source 120. The location 180 is programmed into the programmable memory 170. The location 180 may be programmed into the programmable memory 170 during installation of the navigation/location system 100 or it is possible to program the locations 180 into the programmable memory 170 after the installation of the first light sources 110 and/or the second light sources 120. An updating of the location 180 is possible after the installation of the navigation/location system 100. Hence the location 180 stored in the programmable memory 170 is updateable should any one of the first light sources 110 and/or the second light sources 120 be moved from their respective locations 180. The updating of the programmable memory 170 is possible using the data interface 173. The programmable memory 170 will typically include location data 165. The location data 165 may comprise the longitude, the latitude and an elevation of the first light sources 110 and the second light sources 120. The elevation of the first light sources 110 and/or the second light sources 120 is of interest when using the navigation/location system 100 in a multi-storey building as it will allow identifying an individual one of the storeys of the multi-storey building. [00023] The navigation system 200 of the present disclosure is of interest in situations in which the satellite navigation systems do not work reliably and the first light sources 110 and or the second light sources 120 can be provided. The navigation/location system 100 will provide a location navigation if the satellite navigation system does not provide reliable information, such as indoors where signals from corresponding satellites of the satellite navigation system are not received reliably. [00024] The satellite navigation system may be the global positioning service (GPS), the Olonass system or the Galileo satellite navigation system. The GPS system uses the NMEA protocol as the satellite navigation protocol. Without any limitation the NMEA protocol may be replaced by a corresponding satellite navigation protocol of positional information according to another satellite navigation system. The navigation/location system 100 is typically stored in an office building, a warehouse, a shopping centre, a geriatric care centre, a hospital, hotel, museum or exhibition hall or in other buildings where the location 180 must be determined with a degree of accuracy. It is possible also to conceive of the installation of the navigation/location system 100 in a road tunnel, railway tunnel, mine or sewage tunnel. The benefits of the navigation/location system 100 in these applications will be explained later in the disclosure.

[00025] Light from each one of the first light sources 110 and/or each one of the second light sources 120 can be modulated at a modulation frequency. The modulation frequency is chosen such that the modulation is substantially invisible or unobservable to an average human eye. This is done by ensuring mat average power of the first light sources 110 and the second light sources 120 is independent of the modulated information, otherwise a change in illumination might be observed by the human eye. A frequency pair is used for representing digital zeros and digital ones when modulating light emitted by the first light sources 110 and/or the second light sources 120. The pair of modulation frequencies may be used for encoding the digital zeros and the digital ones of the first light sources 110. Another pair of modulation frequencies may be used for encoding the digital zeros and the digital ones for the second light sources 120. The first frequency pair may be, for example, 30 and 70 kHz, but is not limited thereto. The other frequency pair may be 130 and 170 kHz, but is not limited thereto.

[00026] The modulation of the light enables die transmission of data to a navigation device 200. For example, each one of the first light sources 110 will transmit a first location signal 130 indicating the location 180 of the transmitting first light source 110. Simi- lariy each one of the plurality of second lights sources 120 will transmit a second location signal 140 indicating the location 180 of the second light source 120. Adjacent ones of the first light source 110 and the second light source 120 will generally generate the first loca- tion signal 130 and the second location signal 140 at different pairs of modulation frequencies. The first location signal 130 and the second location signal 140 are encoded using the NMEA 183 protocol. Other protocols can be used as long as they indicate reliably the position of the first light sources 10 and the second light sources 120.

[00027] In one aspect of the invention the NMEA 183 data are encoded using an FSK method. In this method a modulation frequency of 30kHz represents a digital 0 and a modulation frequency of 70kHz represents a digital 1. [00028] It will be noted that the protocol chosen to transmit the first location signal 130 and the second location signal 140 should ensure mat the average power emitted by the first light sources 110 and the second light sources 120 is similar - otherwise some of the first light sources 110 will appear "darker" to the human eye than others. The first location signal 130 and the second location signal 140 are transmitted over 230ms that al- lows 68 bits of data to be transmitted. There follows a pause and the first location signals 130 and the second location signals 140 are then retransmitted. The navigation/location system 100 further comprises a receiver 290. The receiver 290 is adapted to receive the position 180 from a navigation/location device 200, as will be explained later. [00029] Fig. 2 shows an example of a navigation/location device 200 in one aspect of mis disclosure. It will be noted mat the navigation location device 200 illustrated herewith is generic in nature. The navigation location device 200 could be, but is not limited to, a mobile telephone or OPS receiver as will be explained below. [00030] The navigation location device 200 includes a location signal receiver 210 that is adapted to receive the light from the first light sources 110 and/or the second light sources 120. The location signal receiver 210 is, for example, a camera, a camera on the mobile telephone or otherwise a dedicated signal receiver. The location signal receiver 210 or the dedicated signal receiver may use a photodiode to detect the light with filters to en- sure that only light at the required modulation frequency or pairs of modulation frequencies are detected. The navigation device 200 further comprises a map file receiver 215 which purpose will be explained subsequently, a memory 220 for storing the map file 160, a processor 230 and, optionally, a display 240. The navigation/location device 200 optionally further comprises a transmitter 280. The transmitter 280 is adapted to transmit the location 180 to a receiver 290 of the navigation/location system 100. [00031] The processor 230 is designed to receive the location data transmitted in the first location signal 130 and/or the second location signal 140 and compare the location data with the map file 160 in the memory 220 to determine the location 180 of the navigation device 200 and, if required, display the location 180 or a navigation on the display 240. This is typically done by logically overlaying the location data on the map file 160. Such systems are known, for example, OTSI Explorer or OZIexplore.

[00032] The map file 160 can be either pre-stored in the navigation/location device 200 or can be loaded into the navigation memory 220 using the map transmission unit 150. The transfer of the location data 165 in the map file 160 to the navigation/location device 200 can be carried out using a protocol such as, but not limited to, a blue tooth or wireless LAN protocol.

[00033] The operation 300 of the navigation/location system 100 will now be described with reference to Fig. 3. Let us suppose that a human carrying the naviga- tion/location device 200 enters in step 303 a building in which the navigation system 100 is installed. The navigation location device 200 requires the map file 160 in the navigation memory 220 and a check is made in step 305 to determine whether the navigation device 200 includes the map file 160. It will be noted mat the navigation location device 200 may have been pre -supplied with a number of the map files 160 in advance. Alternatively die navigation/location device 200 may have previously uploaded the map file 160 on entering the building. If the map file 160 is not included in the navigation device 200 then the map file 160 is uploaded in step 307.

[00034] The step 305 of checking whether the navigation/location device 200 in- eludes the map file 160 may be omitted, if the navigation location device 200 will never be leaving the building. Likewise if the map file 160 does not change, a (re-)loading of the map 307 may not be required. [00035] In a step 310 the first location signals 130 are generated for the first light sources 110. In a step 310a the first location signals 130 may be generated at a pair of modulation frequencies.

[00036] In a step 310b the second location signals 140 are generated for the second light sources 120. The second location signals 140 may be generated at the other pair of modulation frequencies, as explained above. The steps 310, 310a may be executed exclusively or in combination with the step 310b depending on whether the second location sig- nals 140 are being provided.

[00037] In a step 315 the first location signals 130 are transmitted using the satellite navigation protocol. The step 315 may be sufficient for the transmitting if die second light sources 120 are not provided. A step 315a is carried out if the second light sources 120 are present In the step 315a the second location signals 140 are transmitted from the second light sources 120 using the satellite navigation protocol. The step 315 may be executed exclusively, if only the first light sources 110 are provided or in combination with the step 315a if the first light sources 110 and the second light sources 120 are provided. In a step 320 first location signals 130 are received The first location signals 1 0 may be, for ex- ample, received by the navigation/location device 200. The step 320 of the receiving may be sufficient if only the first light sources 110 are provided. A step 320a of receiving the second location signals 140 may be of interest if the second light sources 120 are provided The step 320 may be carried out individually or in combination with the step 320a. [00038] In a step 330 the location 180 is determined using the received first location signals 130. The step 330 is of interest if the first light sources 110 are provided A step 330a is of interest if the second light sources 120 are provided

[00039] The step 330a comprises a determining of the location 180 using the re- ceived second location signal 140. The first location signal 130 and/or the second location signal 140 may be received by the navigation/location device 200. The detennining 330, 130 and/or the second location signal 140 with the map file 160. The result can be displayed in a step 340 on the display 240. The receiving 320, 320a may be carried out using the location signal receiver 210 (see Figure 2). 100040] After the determining 330, 330a the navigation/location device 200 may use the transmitter 280 for transmitting the location 180 to the receiver 290 of the navigation/location system 100, as discussed with respect to Figures 1 and 2. The transmitter 280 and the receiver 290 may be of interest when the navigation/location system 100 is used for locating an object, such as a valuable hem, a person or mobile objects, such as a clean- ing unit

[00041] For the navigation/location system 100 it is possible to use a first polarisation for the first light sources 110. Providing the first light sources 110 with some polarisation filters, such as polarisation foils the signal receiver 210 may as well be covered with the polarisation filter. It will be appreciated that the signal receiver 210 covered with the polarisation filter will receive a maximal portion of the first location signal 130 if the alignment of the polarisation filter on the signal receiver 210 and the first light source 110 are substantially identical. If the alignment of the polarisation filters on the signal receiver 210 and the first light source 110 is orthogonal, the first location signal 130 will not be received by the signal receiver. The polarisation filters on the first light source 110 and the navigation/location device 200 provide a receiving 320 of the maximal portion of the first location signal 130 only in a dedicated orientation of the navigation/location device 200. It is to be noted that the polarisation foils on the first light sources 110 and the signal receiver 210 of the navigation/location device 200 may allow indentifying a direction in which the user is directed to walk. For example this direction could be chosen to point towards an exit of the building.

[00042] A provision of directional information is also possible when using the first light sources 110 and the second light sources 120. The first light sources 110 are provided with a polarisation filter so that the first light sources 110 emit the light with a first polarisation. The second light sources 120 are provided as emitting light according to a second polarisation. The first polarisation and the second polarisation are substantially orthogonal so that both polarisations can be clearly distinguished The navigation/location device 200 may separate components of the received signals pertaining to the first polarisation and those components pertaining to the second polarisation. From the information pertaining to the first polarisation and the information pertaining to the second polarisation it is possible to deduce a direction of movement when the user moves f om the first light source 110 to the second light source 120. Close to the first light source 110 the signal receiver 210 will mostly receive the signal components pertaining to the first polarisation. A portion of the signal. The strength of the signal components at the signal receiver 210 pertaining to the second polarisation will continuously increase with a movement of the user towards the second light source 120. Therefore the direction of movement of the user can be determined. It will be appreciated that the provision of the first polarisation and the second polarisation helps increasing an accuracy of the location 180 of the user. The increased accuracy of the location 180 is available at a trade off in the form of higher energy needed as polarisation filters will reduce power level received by the signal receiver 210. If the navi- gation/location system 100 uses the polarisation filters at the first light sources 110 and/or the second light sources 120 and the signal receiver 210, the power level will drop to one half at the signal receiver 210 compared to the power level without the polarisation filters.

[00043] Let us take an example. Suppose the user of the navigation/location device 200 enters a room. A first light source 110a is located at position (2,1,5) in the room. The first light source llOa will generate and transmit a first location signal 130 in step 310, 310a indicating mis position (2,1,5) that will be picked up by the navigation location device 200. The result will be displayed (step 340) on the display 240. The user therefore knows his or her location. It will be appreciated that the user will not know exactly his or her location - merely the location 180 of the first light source 110 transmitting the received first location signal 130. The choice of coordinate system used is immaterial. It may be of interest to use the WOS84 coordinate system used by the OPS system, which will simplify the navigation/location system 100 and the navigation location device 200. [00044] Suppose the user now moves through the room. At some stage the user will receive (step 320a) the second location signal 140 from the second light source 120b indicating mat the user is now at a new location 180' having different coordinates, e.g. (2, 4, 8). The navigation/location device 200 will indicate in step 340 the new location 180' on the display 240. It will be appreciated dial at some stage there will be a switch-over of the receipt of the first location signal 130 to the second location signal 140. At this point the navigation location device 200 will determine in step 330, 330a which one of the first loca- tion signal 130 and/or the second location signal 140 is die stronger signal and will assume that the user is closest to the stronger signal and display in step 340 the location 180 of die first light source 110 or the second light source 120 transmitting the stronger signal

[00045] It will be noted that there is no need to "triangulate" die user's position by using more than one of the first location signals 130 or die second location signals 140. The navigation/location unit 200 uses die strongest signal to determine in step 330, 330a and display in step 340 the location 180. The accuracy of the determination of the location 180 is dependent on the number of the first light sources 110 and die second light sources 120 present in the room and/or building.

[00046] It has been noted above that the modulation frequency or the pair of modulation frequencies of adjacent ones of the first light sources 110 and the second light sources 120 are different It will be understood from this example that if adjacent ones of the first light sources 110 and the second lights sources 120 transmitted the first location signal 130 and die second location signal 140 at the same frequency or the same pair of modulation frequencies then at some points within the building there would be interference between the first location signal 130 and the second location signal 140 which would lead to loss of information. It will be further appreciated that die first light sources 110 and the second light sources 120 can be arranged such that the first location signal 130 and the second location signal 140 are sufficiently directional that only two different modulation frequencies or two pairs of the modulation frequencies are required. However, further modulation frequencies could be used if required It will be appreciated that die use of a single light source can be adequate in some instances, e. g. in a small room. [00047] In a further aspect of the invention die navi gation/location device 200 can be combined with the OPS receiver noted above. The user outside of the building could use "traditional" GPS data to determine the location from the satellites. Within the building the navigaticm/locaiion device 200 could automatically switch to using the first location signals 130 and/or the second location signals 140 when the GPS signals were no longer available. Since the first location signals 130 and the second location signals 140 transmit data using the NMEA protocol that is the same protocol that the GPS receiver produces, there is little extra software required.

[00048] The navigation/location system 100 and the navigation/location devices 200 are useable when the satellite navigations system is not reliably available. Typically a satellite navigation system is "blind" within a tunnel or a building, as there may be no reliable reception of the signals emitted by the satellite navigation system. The navigation/location system 100 and the navigation/location device 200 of the present disclosure will allow an accurate navigation/location within the tunnel or the building. The navigation/location system 100 and/or the navigation/location device 200 described in this disclosure enable a human to locate himself or herself within a building.

[00049] The navigation/location system 100 in combination with the navigation/location device 200 would also allow a more flexible arrangement of a storage warehouse than is currently possible. To date guidance tracks are provided on a floor of die warehouse for trucks to move around. The guidance tracks on the floor may be expensive and rather difficult to adapt to changes to the floor plans of the building. The navigation/location system 100 and or the navigation location device 200 could be adapted to allow a programming of the trucks. Such trucks would know their location 180 from the first location signals 130 and or the second location signals 140. [00050] The present disclosure may help to manage an old person's home with dementia patients carrying the navigation/location device 200. If one of the patients goes missing, the location information 180 sent to the receiver 290 may help finding the missing patient Therefore tile present disclosure provides an increased mobility and independence to patients in an elderly home or a hospital. The teachings of the disclosure are equally applicable for children and animals. Children could be provided, for example, with the navigation location device in the exhibition hall or shopping centre. [00051] Any object equipped with the navigation location device 200 may be located as soon as the first location signal 130 and/or the second location signal 140 has been received by the navigation/location device 200 and successfully transmitted to the receiver 290. The receiving at the receiver 290 will make the position 180 of the naviga- tion/location device 200 known to the navigation/location system 100. The navigation/location system 100 may be adapted to provide a warning to a person such that the object or the person equipped with the navigation/location unit 200 can be retrieved.

[00052] A cleaning system can also be equipped with the navigation/location device 200 and use the navigation/location system 100 to automatically clean the room and return to a charging unit when the cleaning unit required additional power or water. In this case the cleaning system would not necessarily require the display 240. Current cleaning units rely on magnetic fields to locate the charging unit The cleaning unit can become confused if an object - such as a wall - is placed between the charging unit and the cleaning unit The navigation location system 100 enables the cleaning unit to negotiate such obstacles.

[00053] Having thus described the present invention in detail, it is to be understood mat the foregoing detailed description of the invention is not intended to limit the scope of the invention thereof. What is desired to be protected by letters patent is set forth in the following claims.

Claims

CLAIM: A navigation location system (100) comprising at least one first light source (110a, 110b, l lOn) being adapted to generate at least one first location signal (130) using a satellite navigation protocol.

The navigation/location system (100) according to claim 1, wherein each one of the at least one first light sources (110a, 110b, llOn) transmits the digital Os of the at least one first location signal (130) on a different frequency than digital Is of the at least one first location signal (130).

The navigation/location system (100) according to claims 1 or 2, wherein the at least one first light source (110a, 110b, 11 On) generates the at least one first location signal (130) at a first pair of modulation frequencies; and further comprising

at least one second light source (120a, 120b, 120n), adapted to generate at least one second location signal (140) at a second pair of modulation frequencies.

The navigation/location system (100) according to claim 3, wherein the first pair of modulation frequencies and the second pair of modulation frequencies are substantially unobservable to the human eye.

The navigation/location system (100) according to any one of the above claims, wherein at least one of the at least one first light source (110a, 10b, 1 On) or the at least one second light source (120a, 120b, 120n) are selected from the group consisting of white LEDs, infrared LEDs, ultraviolet LEDs, and lasers.

The navigation location system (100) according to any one of claims 3 to 5, wherein a programmable memory 170 is provided for at least one of the at least one first light source (110a, 110b, .... 1 lOn) or the at least one second light source (120a, 120b, .... 120n).

The navigation location system (100) according to any one of claims t to 6, further comprising a receiver (290) for receiving the location (180) from at least one navigation/location device (200).

The navigation/location system (100) according to any one of the above claims, further comprising a map transmission unit (150).

A navigation/location method (300), comprising:

- generating (310) at least one first location signal (130) from at least one first light source (110a, 110b, 11 On);

- transmitting (315) at least one first location signal (130) using a satellite navigation protocol;

- receiving (320) at least one first location signal ( 130); and

- determining (330) a location (180) using the received at least one first location signal (130). 10. The navigation/location method (300) according to claim 9, the step of generating (310) comprising:

- generating (310a) the at least one first location signal (130) at a first pair of modulation frequencies;

- generating (310b) at least one second location signal (140) from at least one second light source (120a, 120b, 120n) at a second pair of modulation frequencies.

11. The navigation/location method (300) according to claim 9 or 10, wherein the transmitting (315) comprises:

- a transmitting (315a) of the at least one second location signal (140) from the at least one second light source (120a, 120b, 120n) using the satellite navigation protocol.

12. The navigation/location method (300) according to any one of claims 10 or 11, wherein the receiving (320) comprises

- a receiving (320a) of the at least one second location signal (140).

13. The navigation/location method (300) according to any one of claims 10 to

12, wherein the step of determining (330) comprises

- determining (330a) the location (180) using the received at least one second location signal (140).

14. The navigation/location method (300) according to any one of claims 9 to

13, further comprising

- receiving a map file (160) with location data (165).

The navigation/location method (300) according to claim 14, wherein the determining (330, 330a) of the location (180) comprises a comparing of at least one of the at least one received first location signal (130) or the at least one received second location signal (140) with the location data (165). 16. The navigation/location method (300) according to any one of claims 9 to

15, wherein the step of determining (330) comprises

- determining (330, 330a) a strongest one of the received at least one first location signal (130) and using the strongest one of the at least one first location signal (130) to determine the location (180).

17. The navigation/location method (300) according to any one of claims 12 to

16, wherein the step of determining (330a) comprises

- determining a strongest one of the received at least one second location signal (140) and using the strongest one of the received at least one second location signal (140) to determine the location (180).

18. A navigation location device (200) comprising: - a location signal receiver (210) for receiving at least one first location signal (130) from at least one first light source (110a, 110b, 1 lOn);

- a memory (220) for storage of a map file (160); and

- a processor (230) for determining a location (180).

19. A navigation/location device (200) according to claim 18, wherein the location signal receiver (210) is adapted to receive at least one second location signal (140) from at least one second light source (120a, 120b, 120n). 20. The navigation/location device (200) according to claim 18 or 19 further comprising a display (240) for displaying the location (180) or a navigation.

21. The navigation/location device (200) according to claim 18 to 20, further comprising a map file receiver (215) for receiving the map file (160).

22. The navigation/location device (200) according to any one of claims 18 to

21, further comprising a receiver (250) for signals from a satellite navigation system. 23. The navigation location device (200) according to any one of claims 18 to

22, comprising a transmitter (280) for transmitting the location (180) to a receiver (290) of a navigation location system (100).

24. Use of the navigation/location device (200) according to any one of claims 18 to 23 or the navigation location system (100) according to anyone of claims 1 to 8 for navigation or location.

25. Use according to claim 24 in at least one of an office building, a warehouse, a store, a shopping centre, an exhibition hall, a museum, a hospital, a build- ing, a geriatric care centre, a hotel, a road tunnel, a railway tunnel, a sewage tunnel or a mine. Use according to claims 24 or 25 for navigation/location of one of a person or an object