METHOD AND SYSTEM FOR DATA TRANSMISSION BY MEANS OF LIGHT

Description

[0001] The invention relates to a method for data transmission by means of light, wherein a transmitter emits light in which the data to be transmitted is encoded, and a receiver receives light emitted by the transmitter. The invention also relates to a system for data transmission by means of light, comprising a transmitter for emitting light in which the data to be transmitted is encoded, and a receiver for receiving light emitted by the transmitter.

[0002] DE 10 2016 010 999 A1 discloses a system and method for determining the position of a vehicle within a facility. The system comprises a vehicle with a receiving module and a stationary transmitting module. The transmitting module has a light source and a first polarization filter, wherein the first polarization filter is designed as a linear polarization filter, so that linearly polarized light can be emitted by the transmitting module. The receiving module has a light sensor, a liquid crystal, and a second polarization filter, wherein the second polarization filter is designed as a linear polarization filter.

[0003] DE 10 2018 006 988 B3 discloses a system and method for data transmission using visible light. The system comprises a receiver with an image sensor whose light-sensitive surface is scanned line by line, and a transmitter with a controllable light source that emits modulated light.

[0004] US 6,310,707 B1 discloses an optical wireless data transmission system with a transmitter having one or more light sources for emitting different types of light, and with a receiver having one or more areas for receiving the light.

[0005] DE 699 01 158 T2 and EP 1 026 840 A1 disclose a method for transmitting information on a light signal, wherein a polarization value of the light signal is set to different values ​​depending on the information values ​​to be transmitted.

[0006] The document DE 10 2014 209 901 A1 describes a communication device for the optical free-space transmission of data with a retroreflector, wherein the retroreflector has an integrated modulation device with which an incident light beam is modulated.

[0007] A polarization-based method for light transmission and a corresponding system are known from CN 107831470 A.

[0008] EP 0 955 738 A2 discloses a polarization-based receiver for reducing background noise in optical links.

[0009] US 2018 / 0240338 A1 discloses a communication device for motor vehicles. The communication device comprises a transmission system for emitting a polarized light beam.

[0010] The invention is based on the object of improving a method and a system for data transmission by means of light.

[0011] The object is achieved by a method for data transmission by means of light having the features specified in claim 1. Advantageous embodiments and further developments are the subject of the subclaims. The object is also achieved by a system for data transmission by means of light having the features specified in claim 8. Advantageous embodiments and further developments are the subject of the subclaims.

[0012] In a method according to the invention for data transmission by means of light, a transmitter emits light in which the data to be transmitted is encoded, and a receiver receives light emitted by the transmitter.

[0013] The transmitter comprises a data field having at least one data element, wherein the at least one data element emits light with a specific data polarization. The data to be transmitted is encoded in the data polarization of the light emitted by the at least one data element. The receiver comprises a polarization unit that detects the respective data polarization of the light emitted by the at least one data element. The receiver also comprises an evaluation unit that decodes the data of the at least one data element to be transmitted from the data polarization of the light emitted by the at least one data element detected by the polarization unit.

[0014] The at least one data element therefore has a data polarization which represents a polarization direction of the light emitted by the at least one data element. A specific data polarization is uniquely assigned to each specific piece of data. The data polarization is not limited to horizontal and vertical, but can have a finer resolution. Depending on the resolution of the data polarization, several different data can be transmitted from one data element. For example, a resolution of eight or more different data polarizations over an angular range of 180° is conceivable. The evaluation unit decodes the data to be transmitted, for example, exclusively from the detected data polarization. However, it is also conceivable for the evaluation unit to decode the data to be transmitted from a combination of the detected data polarization and another polarization.

[0015] The advantage is that the data polarization of the emitted light can be measured relatively accurately, even at a relatively large distance between the transmitter and receiver. Furthermore, only minimal perspective distortion occurs when the light emitted by the transmitter is received.

[0016] According to the invention, the data field comprises at least one data series comprising a plurality of data elements. Each of the data elements emits light with a specific data polarization. The data to be transmitted is encoded in the data polarizations of the light emitted by the data elements. The polarization unit detects the data polarizations of the light emitted by the data elements. By using the plurality of data elements, each of which has its own data polarization, a plurality of data can be transmitted compared to just one data element.

[0017] According to the invention, the data series comprises a reference element that emits light with a reference polarization. The polarization unit detects the reference polarization of the light emitted by the reference element. The evaluation unit decodes the data of the data elements to be transmitted by combining the data polarizations of the light emitted by the data elements and the reference polarization of the light emitted by the reference element.

[0018] The reference element therefore has a reference polarization, which serves as the reference direction for the relative orientation of the data polarization of each individual data element in the data series. The combination of the data polarization and the reference polarization is, for example, the difference between the data polarization of the individual data element and the reference polarization. Thus, the decoding of the data to be transmitted is independent of the orientation of the receiver relative to the transmitter.

[0019] According to another advantageous embodiment of the invention, the data series has a reference element that emits light with a reference polarization. The polarization unit detects the reference polarization of the light emitted by the reference element. The evaluation unit decodes the data to be transmitted from the first data element by combining the data polarization of a light emitted by a first data element and the reference polarization of the light emitted by the reference element. The evaluation unit decodes the data to be transmitted from the subsequent data element by combining the data polarization of a light emitted by a subsequent data element and the data polarization of a light emitted by a previous data element.

[0020] The reference element therefore has a reference polarization, which serves as a reference direction for the relative orientation of the data polarization of the first data element in the data series. The combination of the data polarization of the first data element and the reference polarization is, for example, the difference between the data polarization of the first data element and the reference polarization. The data polarization of a preceding, for example, the first, data element in the data series serves as a reference direction for the relative orientation of the data polarization of a subsequent, for example, the second, data element. The combination of the data polarization of the subsequent data element and the data polarization of the preceding data element is, for example, the difference between the data polarization of the second data element and the data polarization of the first data element.Thus, the decoding of the data to be transmitted is independent of the orientation of the receiver to the transmitter.

[0021] According to an advantageous development of the invention, the data series comprises a separating element that emits light with a separating polarization or unpolarized light. The separating element thus differs from the data elements and the reference element, which emit light with other polarizations. The separating element thus serves as a reference for the data series.

[0022] According to a preferred embodiment of the invention, the elements of the data series are arranged next to one another in a longitudinal direction. The separating element is preferably arranged between the reference element and the data elements.

[0023] Preferably, the elements of the data series have the same length in the longitudinal direction. The separating element, which has the separating polarization or no polarization, advantageously serves as a measure of the length of the elements in the longitudinal direction.

[0024] Preferably, the elements of the data series have the same width in a transverse direction, which runs perpendicular to the longitudinal direction. Preferably, the length is equal to the width. The elements are thus square. However, it is also conceivable for the elements to be rectangular or round, for example.

[0025] According to an advantageous development of the invention, the data field comprises a plurality of data rows. The data rows are arranged next to one another in a transverse direction that runs perpendicular to the longitudinal direction. Using a plurality of data rows also allows for the transmission of a plurality of data rows, compared to using just one data row.

[0026] A system according to the invention for data transmission by means of light comprises a transmitter for emitting light, in which the data to be transmitted is encoded, and a receiver for receiving light emitted by the transmitter. The system according to the invention is configured to carry out the method according to the invention.

[0027] According to an advantageous development of the invention, the transmitter has a light source that radiates through the data field. The at least one data element acts like a polarization filter and only allows light with a specific data polarization to pass through.

[0028] According to another advantageous embodiment of the invention, the data field is designed as a reflector. The at least one data element reflects light with a specific data polarization.

[0029] According to an advantageous embodiment of the invention, the receiver is arranged in or on an autonomously driving vehicle, which has a drive device, an electrical energy storage device for supplying the drive device, and a control unit for controlling the drive device. The drive device comprises, for example, an electric motor, a transmission, and drive wheels. The autonomously driving vehicle is, in particular, a driverless transport system for transporting objects within a technical facility.

[0030] The invention is not limited to the combination of features in the claims. Further possible combinations of claims and / or individual claim features and / or features of the description and / or the figures will become apparent to those skilled in the art, particularly from the problem and / or the problem posed by comparison with the prior art.

[0031] The invention will now be explained in more detail with reference to the accompanying drawings. The invention is not limited to the exemplary embodiments shown in the drawings. The drawings only represent the subject matter of the invention schematically. They show: Figure 1: a schematic representation of a system for data transmission by means of light, Figure 2: a data field in a first orientation, Figure 3: a data field in a second orientation, Figure 4: an exemplary assignment of data to data polarizations, Figure 5: an autonomously driving vehicle according to a first embodiment, Figure 6: an autonomously driving vehicle according to a second embodiment and Figure 7: an autonomously driving vehicle according to a third embodiment.

[0032] Figure 1shows a schematic representation of a system 10 for data transmission by means of light 20. The system 10 for data transmission by means of light 20 comprises a transmitter 14, which emits light 20 in which the data to be transmitted is encoded, and a receiver 12, which receives light 20 emitted by the transmitter 14.

[0033] The transmitter 14 comprises a data field 30. The data field 30 has a plurality of data elements 51 which emit light 20 with specific data polarizations Θ. The data to be transmitted is encoded in the data polarizations Θ of the light 20 emitted by the data elements 51. In this case, the transmitter 14 has a light source 8. The light source 8 is, for example, an LED, a ceiling lamp, or a light bulb which emits unpolarized light. The light source 8 shines through the data field 30, with the data elements 51 acting like polarization filters and only allowing light 20 with a specific data polarization Θ to pass through. The light source 8 can also be omitted. In this case, the data field 30 is designed as a reflector, with the data elements 51 each reflecting light 20 with a specific data polarization Θ.

[0034] The receiver 12 comprises a polarization camera 1, which is capable of detecting the polarization of incident light 20 with an angular resolution of, for example, 1°. The polarization camera 1 has an optical lens 2 and a polarization unit 16. The receiver 12 also includes an aperture 5. The aperture 5 and the lens 2 are arranged such that light 20 incident on the polarization unit 16 first passes through the aperture 5 and the lens 2.

[0035] The polarization unit 16 of the polarization camera 1 detects the respective data polarization Θ of the light 20 emitted by the data elements 51 of the data field 30. The polarization unit 16 comprises a polarization filter 3, which has regions that each transmit light 20 with different polarization, and a pixel block 4, onto which light 20 transmitted by said regions of the polarization filter 3 impinges.

[0036] The receiver 12 also comprises an evaluation unit 6. The evaluation unit 6 decodes the data of the data elements 51 to be transmitted from the data polarizations Θ of the light 20 emitted by the data elements 51, which the polarization unit 16 detects. The evaluation unit 6 is designed, for example, in the form of a digital computer, a processor or an FPGA.

[0037] Figure 2 shows a data field 30 of a transmitter 12 in a first orientation. The data field 30 comprises a data series 40 having a plurality of data elements 51. Each of the data elements 51 emits light 20 with a specific data polarization Θ. The data to be transmitted is encoded in the data polarizations Θ of the light 20 emitted by the data elements 51.

[0038] The data series 40 also has a reference element 50, which emits light 20 with a reference polarization Θref. The data series 40 further has a separating element 59, which emits unpolarized light 20. The data elements 51, the reference element 50, and the separating element 59 of the data series 40 are arranged next to one another in a longitudinal direction X.

[0039] The elements 50, 51, 59 of the data series 40 have an equal length L in the longitudinal direction X. The elements 50, 51, 59 of the data series 40 also have an equal width B in a transverse direction Y, which runs perpendicular to the longitudinal direction X. The elements 50, 51, 59 of the data series 40 are rectangular in the present case. Other configurations of the elements 50, 51, 59 are also conceivable. Furthermore, it is conceivable for the data field 30 to comprise a plurality of data series 40, which are arranged adjacent to one another, in particular, in the transverse direction Y.

[0040] The polarization unit 16 of the receiver 12 detects apparent polarizations P of the light 20 emitted by the data elements 51 and an apparent reference polarization Pref of the light 20 emitted by the reference element 50. Furthermore, the polarization unit 16 detects the unpolarized light 20 emitted by the separating element 59. The polarization unit 16 has a field of view extending in a horizontal direction H and in a vertical direction V perpendicular thereto.

[0041] The data polarizations Θ of the data elements 51 and the reference polarization Θref of the reference element 50 are defined with respect to the longitudinal direction X. However, the polarization unit 16 detects the apparent polarizations P and the apparent reference polarization Pref with respect to the horizontal direction H. The reference polarization Θref is parallel to the longitudinal direction X and is thus 0°.

[0042] In the here in Figure 2In the illustration shown, the data field 30 of the transmitter 12 is in a first orientation in which the longitudinal direction X runs parallel to the horizontal direction H and the transverse direction Y runs parallel to the vertical direction V. The reference polarization Θref of the reference element 50 thus runs in the longitudinal direction X and in the horizontal direction H. The apparent reference polarization Pref therefore corresponds to the reference polarization Θref and is thus also 0°.

[0043] The apparent polarizations P detected by the polarization unit 16 with respect to the horizontal direction H thus correspond to the data polarizations Θ of the data elements 51 with respect to the longitudinal direction X. The polarization unit 16 thus recognizes the data polarizations Θ of the data elements 51 as the detected apparent polarizations P.

[0044] The following applies to the detected data polarizations Θ of the data elements 51: ⊖ = P

[0045] Figure 3shows a data field 30 of a transmitter 12 in a second orientation. In the illustration shown here, the data field 30 of the transmitter 12 is in a second orientation, in which the longitudinal direction X is inclined to the horizontal direction H and the transverse direction Y is inclined to the vertical direction V. The reference polarization Θref of the reference element 50 thus runs in the longitudinal direction X, but inclined to the horizontal direction H. The apparent reference polarization Pref is therefore also inclined to the reference polarization Θref.

[0046] The apparent polarizations P detected by the polarization unit 16 with respect to the horizontal direction H are inclined to the data polarizations Θ of the data elements 51 with respect to the longitudinal direction X by the apparent reference polarization Pref. The polarization unit 16 thus detects the data polarizations Θ of the data elements 51 as the difference between the detected apparent polarizations P and the detected apparent reference polarization Pref.

[0047] The following applies to the detected data polarizations Θ of the data elements 51: ⊖ = P - Pref

[0048] Figure 4 shows an exemplary assignment of data d to data polarizations Θ. Each data element 51 transmits a data item d with m bits.

[0049] The data polarization Θ of the respective data element 51 is calculated, for example, for all data elements 51 of the data series as follows: ⊖ = 2 d + 1 * 180 ° / 2 m + 1

[0050] In this case, the evaluation unit 6 decodes the data d of the data elements 51 to be transmitted from the data polarization Θ of the data elements 51 detected by the polarization unit 16.

[0051] It is also conceivable that the data polarization Θ of the data elements 51 is calculated as a function of the reference polarization Θref of the reference element 50, for example as follows: ⊖ = ⊖ ref + 2 d + 1 * 180 ° / 2 m + 1

[0052] In this case, the evaluation unit 6 decodes the data d of the data elements 51 to be transmitted from a combination of the data polarizations Θ of the data elements 51 and the reference polarization Oref of the reference element 50.

[0053] Furthermore, it is conceivable that the data polarization Θ of the first data element 51 is calculated as a function of the reference polarization Θref of the reference element 50, for example as follows: ⊖ = ⊖ ref + 2 d + 1 * 180 ° / 2 m + 1 mod 180 ° and that the data polarization Θafter of a subsequent data element 51 is calculated as a function of the data polarization Θbefore of a previous data element 51, for example as follows: ⊖ nach = ⊖ vor + 2 d + 1 * 180 ° / 2 m + 1 mod 180 °

[0054] In this case, the evaluation unit 6 decodes the data to be transmitted of the first data element 51 from a combination of the data polarization Θ of the first data element 51 and the reference polarization Θref of the reference element 50. Likewise, the evaluation unit 6 decodes the data to be transmitted of the subsequent data element 51 from a combination of the data polarization Θ of a subsequent, for example the second, data element 51 and the data polarization Θ of a previous, for example the first, data element 51.

[0055] Each specific data d with 0 ≤ d < 2 m< is uniquely assigned to a specific data polarization Θ with 0° < Θ < 180°. The exemplary assignment of data d to data polarizations Θ is for m = 3 in Figure 4 shown in a diagram. The data d is represented as three-digit binary numbers, and the associated data polarizations Θ are given as angles.

[0056] Figure 5 shows an autonomously driving vehicle 25 according to a first embodiment. The vehicle 25 has a drive device, an electrical energy storage device for supplying the drive device, and a control unit for controlling the drive device. The vehicle 25 is located on a horizontally oriented floor.

[0057] The vehicle 25 has a receiver 12. The receiver 12 is vertically oriented. Light 20, which is emitted, for example, by a transmitter 14 mounted on a ceiling above the vehicle 25, can be received by the receiver 12.

[0058] Figure 6 shows an autonomously driving vehicle 25 according to a second embodiment. The vehicle 25 has a drive device, an electrical energy storage device for supplying the drive device, and a control unit for controlling the drive device. The vehicle 25 is located on a horizontally oriented floor.

[0059] The vehicle 25 has a receiver 12. The receiver 12 is oriented horizontally. The vehicle 25 further has a mirror 26. The mirror 26 is arranged and oriented such that light 20, which is emitted, for example, by a transmitter 14 mounted on a ceiling above the vehicle 25, is deflected by the mirror 26 and can be received by the receiver 12.

[0060] Figure 7 shows an autonomously driving vehicle 25 according to a third embodiment. The vehicle 25 has a drive device, an electrical energy storage device for supplying the drive device, and a control unit for controlling the drive device. The vehicle 25 is located on a horizontally oriented floor.

[0061] The vehicle 25 has a receiver 12. The receiver 12 is oriented horizontally. Light 20, which is emitted, for example, by a transmitter 14 mounted on a wall at the height of the vehicle 25, can be received by the receiver 12. List of reference symbols

[0062] 1Polarization camera 2Lens 3Polarization filter 4Pixel block 5Aperture 6Evaluation unit 8Light source 10System 12Receiver 14Transmitter 16Polarization unit 20Light 25Vehicle 26Mirror 30Data field 40Data series 50Reference element 51Data element 59Separator BWidth LLength HHorizontal direction VVertical direction XLongitudinal direction YTransverse direction ΘData polarization ΘrefReference polarization PApparent polarization PrefApparent reference polarization

Claims

1. Method for transmitting data by means of light (20), wherein a transmitter (14) emits light (20) in which the data to be transmitted are encoded, and a receiver (12) receives light (20) emitted by the transmitter (14), wherein the transmitter (14) comprises a data field (30) which has at least one data element (51), wherein the at least one data element (51) emits light (20) having a specific data polarisation (Θ), wherein the data to be transmitted are encoded in the data polarisation (Θ) of the light (20) emitted by the at least one data element (51), and wherein the receiver (12) comprises a polarisation unit (16) which detects the particular data polarisation (Θ) of the light (20) emitted by the at least one data element (51), and wherein the receiver (12) comprises an evaluation unit (6) which decodes the data to be transmitted of the at least one data element (51) from the data polarisation (Θ), detected by the polarisation unit (16), of the light (20) emitted by the at least one data element (51), wherein the at least one data element (51) has a data polarisation (Θ) which represents a polarisation direction of the light (20) emitted by the at least one data element (51), and each specific piece of data is uniquely assigned a specific data polarisation (Θ), characterised in that the data field (30) comprises at least one data series (40) which has a plurality of data elements (51), wherein each of the data elements (51) emits light (20) having a specific data polarisation (Θ), and wherein the polarisation unit (16) detects the data polarisations (Θ) of the light (20) emitted by the data elements (51), and in that the elements (50, 51) of the data series (40) are arranged next to one another in a longitudinal direction (X), and in that the data series (40) has a reference element (50) which emits light (20) having a reference polarisation (Θref), wherein the polarisation unit (16) detects the reference polarisation (Θref) of the light (20) emitted by the reference element (50), and in that the evaluation unit (16) decodes the data to be transmitted of the data elements (51) from a link between the data polarisations (Θ) of the light (20) emitted by the data elements (51) and the reference polarisation (Θref) of the light (20) emitted by the reference element (50).

2. Method according to claim 1, characterised in that the evaluation unit (6) decodes the data to be transmitted of a subsequent data element (51) from a link between the data polarisation (Θ) of light (20) emitted by the subsequent data element (51) and the data polarisation (Θ) of light (20) emitted by a preceding data element (51).

3. Method according to any of claims 1 to 2, characterised in that the data series (40) has a separating element (59) which emits either light (20) having a separating polarisation or unpolarised light (20).

4. Method according to any of claims 1 to 3, characterised in that the elements (50, 51, 59) of the data series (40) are of the same length (L) in the longitudinal direction (X).

5. Method according to any of claims 1 to 4, characterised in that the elements (50, 51, 59) of the data series (40) are of the same width (B) in a transverse direction (Y) which runs at right angles to the longitudinal direction (X).

6. Method according to any of claims 1 to 5, characterised in that the data field (30) comprises a plurality of data series (40), wherein the data series (40) are arranged next to one another in a transverse direction (Y) which runs at right angles to the longitudinal direction (X).

7. System (10) for transmitting data by means of light (20), comprising a transmitter (14) for emitting light (20) in which the data to be transmitted are encoded, and a receiver (12) for receiving light (20) emitted by the transmitter (14), characterised in that the system (10) is configured for carrying out the method according to any of the preceding claims.

8. System (10) according to claim 7, characterised in that the transmitter (14) has a light source (8) which irradiates the data field (30).

9. System (10) according to claim 8, characterised in that the data field (30) is in the form of a reflector.

10. System (10) according to any of claims 7 to 9, characterised in that the receiver (12) is arranged in or on a self-driving vehicle (25) which has a drive apparatus, an electrical energy storage device for powering the drive apparatus and a control unit for controlling the drive apparatus.