RFID Apparatus for Communicating with RFID Transponders and Method of Associating RFID Transponders

Abstract

An RFID apparatus for communicating with RFID transponders in accordance with an RFID protocol is provided that has an antenna, an RFID transceiver for emitting and receiving RFID signals with the aid of the antenna and has a control unit that is configured to encode RFID information into an RFID signal in accordance with an RFID protocol or to read said information from the RFID signal and to determine at least one spatial and/or speed parameter of an RFID transponder with reference to the RFID signal. The control unit is further configured to read container transponders and object transponders and to associate an object transponders with a container transponder with reference to the respective spatial and/or speed parameters.

Claims

1. An RFID apparatus for communicating with RFID transponders in accordance with an RFID protocol, the RFID apparatus comprises: an antenna, an RFID transceiver for emitting and receiving RFID signals with the aid of the antenna, and a control unit that is configured to encode RFID information into an RFID signal in accordance with an RFID protocol or to read said information from the RFID signal and to determine at least one spatial and/or speed parameter of an RFID transponder with reference to the RFID signal, wherein the control unit is further configured to read container transponders and object transponders and to associate an object transponder with a container transponder with reference to the respective spatial and/or speed parameters.

2. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to determine the angle at which an RFID transponder is detected as the spatial parameter.

3. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to determine the spacing at which an RFID transponder is detected as the spatial parameter.

4. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to associate all the object transponders at a maximum spacing with a container transponder as the center.

5. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to associate all the object transponders having a similar speed with one container transponder.

6. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to draw an outer border with reference to at least two container transponders and to associate all the object transponders arranged therebetween with the container transponders.

7. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to associate container transponders with one another by a comparison of spatial and/or speed parameters.

8. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to determine spatial and/or speed parameters at at least two points in time and to support the association thereon.

9. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to recognize when a changed association occurs on a repeated association of object transponder to container transponder.

10. The RFID apparatus in accordance with claim 1, wherein the control unit is configured to take account of a compulsory guidance of the RFID transponders during the determination of the spatial and/or speed parameters and during the association.

11. A method of associating RFID transponders, wherein communication with the RFID transponders takes place in accordance with an RFID protocol in that an RFID signal is emitted and received and RFID information is encoded into the RFID signal or is read from the RFID signal in accordance with the RFID protocol, with at least one spatial and/or speed parameter of an RFID transponder being determined with reference to the RFID signal, wherein container transponders and object transponders are read out and an object transponder is associated with a container transponder with reference to the respective spatial and/or speed parameters.

Description

[0021] The invention will be explained in more detail in the following also with respect to further features and advantages by way of example with reference to embodiments and to the enclosed drawing. The Figures of the drawing show in:

[0022] FIG. 1 a simplified block diagram of an RFID apparatus with an RFID transponder in its display;

[0023] FIG. 2 an example of an association of object transponders with a container transponder that is located at the center of a box;

[0024] FIG. 3 an example of an association of object transponders with container transponders that mark the front and rear ends of a box; and

[0025] FIG. 4 an example of an association of object transponders to container transponders based on the reading angle.

[0026] FIG. 1 shows a schematic overview representation of an RFID apparatus 10 and of an RFID transponder 12 arranged in an exemplary manner in its reading range. The RFID apparatus 10 in this embodiment has two antennas 14a-b to be able to carry out a localization of the RFID transponders 12 over phase measurements of the incoming waves. In alternative embodiments, there is only one antenna or, conversely, there are further antennas.

[0027] The RFID apparatus 10 transmits and receives RFID signals via the antennas 14a-b with the aid of a transceiver 16. A control unit 18, for example having a digital module such as a microprocessor or an FPGA (field programmable gate array) controls the routines in the RFID apparatus 10 and is able to encode RFID information into an RFID signal or to read RFID information from an RFID signal. A wired or wireless connector 20 serves to integrate the RFID apparatus 10 into a higher ranking system.

[0028] The communication preferably takes place in accordance with a known RFID protocol, in particular ISO 18000-6 or EPC Generation 2 UHF RFID and the steps and components required for this are known per se and are considered as known in the same way as the exact design of the RFID apparatus 10 going beyond the rough functional blocks of FIG. 1.

[0029] The RFID apparatus 10 is also able to detect spatial or speed information of the RFID transponder 12 in addition to the detection and optionally change of the actual RFID information stored on the RFID transponder 12 such as its identification. Properties of the carrier wave itself are evaluated for this purpose, that is the RFID signal, and not the RFID information stored on the RFID transponder 12 and encoded into the RFID signal.

[0030] In the embodiment of FIG. 1, the different phase at the two antennas 14a-b is evaluated. The angle at which the RFID transponder 12 was read can first be thereby determined and a spatial association of the tags can be carried out at least angle-wise. It is also conceivable to determine the spacing of the RFID transponder 12 from the phase information. This ambiguously remains module , but the carrier wavelength can nevertheless deliver useful information. In addition, the non-ambiguity range can also be expanded, for example by measuring using two frequencies. Further possibilities of detecting spatial or speed information include evaluations of the level (RSSI) or measurements of the Doppler effect. The detection of spatial or speed information by an RFID apparatus 10 is known per se and will therefore not be described more exactly; the RFID apparatus 10 in accordance with the invention only utilizes such information.

[0031] It is also conceivable to acquire additional spatial or speed information by further sensors such as a camera or a laser scanner, to obtain them as parameters such as the conveying speed of a conveyor belt on which RFID transponders 12 are located or to obtain such information from another system such as the control of a vehicle or other transport means conveying RFID transponders 12.

[0032] The spatial and speed information are now used by the control unit 18 to associate RFID transponders 12 with one another. In this respect, the control unit 18 can also be implemented wholly or partly outside the RFID apparatus 10. This is illustrated for a plurality of examples with respect to FIGS. 2 to 4.

[0033] FIG. 2 shows an example of an association of object transponders 22 with a container transponder 24. The object transponders 22 and container transponders 24 are each RFID transponders, but the control unit 18 is also able to recognize container transponders 24 as such with reference to the identification or to any other information that it has itself or reads by RFID. The container transponder 24 identifies a container 26 on a conveyor belt 28 in which objects, not themselves shown, with object transponders 22 are located. The conveyor belt 28 is only one application example; they can alternatively be any desired containers moved passively or actively or also not moved.

[0034] The association objective now comprises associating the object transponders 22 in the container 26 to its container transponder 24. An object transponder 22a outside the container 26, that is likewise located in the reading range, should in contrast not be associated with the container transponder 24. For this purpose, the container transponder 24 is attached centrally in the container 26. In addition, the control unit 18 is aware, optionally by reading the container transponder 24, of how long the container 26 is in the conveying direction. All the object transponders 22 that are located at a maximum at the spacing of half the container length from the container transponder 24 are now consider as affiliated in the container 26 and thus with the container transponder 24. It is sufficient for this distinction to know the reading angle and to determine an angular range for the container 26 with reference to the container dimensions and to the reading angle of the container transponder 24. Different or more exact spatial information is, however, equally conceivable. It is also conceivable to check the angle in the vertical direction fully analogously with reference to the height of the container 26. If the position of the transponders 22, 24 in the depth direction is also known, for instance by phase measurement or RSSI measurement, the depth of the container 26 can also fully correspondingly be checked.

[0035] FIG. 3 shows a further example of an association of object transponders 22 with a container transponder 24. Unlike FIG. 2, two container transponders 24a-b are here located at the front and rear at the container 26 in the conveying direction. Precisely those object transponders 22 that are disposed between the container transponders 24a-b are associated with the container transponders 24a-b and thus with the container 26. The remaining statements on FIG. 2 apply accordingly. It is conceivable to provide further container transponders to define the boundary line within which the object transponders 22 to be associated are disposed more precisely and in further degrees of freedom than only the conveying direction. This is above all useful when the container 26 is not located on a conveyor belt 28 or when there are a plurality of conveyor belts in relatively close adjacency next to one another or above one another.

[0036] FIG. 4 shows a further example of an association of object transponders 22 with container transponders 24. It is here, for example, a question of goods stacks on pallets. It can directly be seen that a separation and association with the left, middle and right pallets is possible with reference to the reading angle. If the reading angle is also detected in the vertical direction, pallets can also be distinguished in stacked form.

[0037] It generally applies that the association can be the more complex, the better the spatial and speed information is. On a 3D localization of transponders, containers standing behind one another can, for example, also be correctly processed or even nested arrangements in which a plurality of transport containers full of goods stand on a pallet. In this case, a kind of high-ranking meta-container transponder can be present and the association problem becomes a 1 to m to n problem or an even more using nested problem that, however, remains solvable completely analogously with correspondingly good spatial and speed information.

[0038] The association also allows an error recognition if it changes over the course of time. For example, an object with an object transponder 22 that does not move in conformity with its container 26 is no longer in the container 26 or has fallen down.

[0039] A movement of the containers 26 and objects during the detection is not required. However, it does have advantages since a multiple detection and association becomes possible. In addition to statistical improvements, the transponders 22, 24 are thereby observed from different positions so that the risk of an unread transponder 22, 24 that is only weakly reached in an instantaneous position falls considerably. All the transponders 22, 24 are furthermore seen from different angles. Particularly with large containers 26 such as a pallet and with object transponders 22 at their margins, this distinction improves whether the object transponder 22 is still located at the outer margin of the one container 26 or already that of the adjacent container 26.