Search

EP-4742087-A1 - RFID SYSTEM

EP4742087A1EP 4742087 A1EP4742087 A1EP 4742087A1EP-4742087-A1

Abstract

A system for locating a transponder intended for identification in the radio frequency range (RFID transponder), in relation to an RFID reader, comprises the RFID reader, which transmits a request signal at a predetermined frequency; the RFID transponder, which receives the request signal and sends a response signal back to the RFID reader; and an auxiliary device with at least one transmitter and at least one receiver. The transmitter emits at least one auxiliary signal that differs in frequency from the RFID reader's request signal. The receiver detects at least one detection signal generated by the interaction of the auxiliary signal with the RFID transponder. Furthermore, the auxiliary device is configured to determine, based on the detection signal, at least one piece of information for locating the RFID transponder in relation to the RFID reader.

Inventors

  • SOCK, Bjoern
  • SCHMIDT, Vincent
  • Pudenz, Florian
  • Schwarzkopf, Sebastian

Assignees

  • SICK AG

Dates

Publication Date
20260513
Application Date
20241106

Claims (15)

  1. System (100) for locating a transponder (120) intended for identification in the radio frequency range (RFID transponder) with respect to an RFID reader (110), wherein the system (100) comprises: the RFID reader (110) which sends a request signal (132) at a predetermined frequency, the RFID transponder (120), which receives the request signal (132) and sends a response signal (142) back to the RFID reader (110), and an additional device (150) with: at least one transmitting unit (151, 152, 170) which transmits at least one additional signal (160, 161) which differs from the request signal (132) with respect to frequency, and at least one receiving unit (151, 152, 180, 182) that detects at least one detection signal (162, 163) that is generated by an interaction of the additional signal (160, 161) with the RFID transponder (120), wherein the additional device (150) is designed to determine at least one piece of information for the localization of the RFID transponder (120) in relation to the RFID reader (110) on the basis of the detection signal (162, 163).
  2. System (100) according to claim 1, wherein the additional signal (160, 161) sent by the transmitting unit (151, 152, 170) of the auxiliary device (150) is a non-modulated signal.
  3. System (100) according to claim 1 or 2, wherein the frequency of the additional signal (160, 161) lies outside a frequency band that is intended for communication between the RFID reader (110) and the RFID transponder (120).
  4. System (100) according to one of the preceding claims, wherein the transmitting unit (151, 152) emits at least two additional signals (160, 161) which each differ from the request signal (132) with respect to frequency, and the receiving unit (151, 152) detects at least two detection signals (162, 163) at the respective frequency of at least two additional signals (160, 161).
  5. System (100) according to claim 4, wherein the additional device (150) is designed to determine a distance (d), a direction of movement and a speed of the RFID transponder (120) relative to the RFID reader (110) based on the at least two detection signals.
  6. System (100) according to claim 4 or 5, wherein the additional device (150) comprises a first and a second transmitting unit (151, 152) as well as a first and a second receiving unit (151, 152), the first transmitting unit (151) and the first receiving unit (151) are spatially separated from the second transmitting unit (152) and the second receiving unit (152) by a predetermined distance (a) between them and the additional device (150) is designed to determine an angle of the RFID transponder (120) relative to a predetermined direction based on the to determine at least two detection signals (162, 163) and based on the predetermined distance (a).
  7. System (100) according to one of the preceding claims, wherein the RFID reader (110) is designed to control the auxiliary device (150) in such a way that the transmitter unit (151, 152, 170) of the auxiliary device (150) only sends the auxiliary signal (160, 161) when the RFID reader (110) sends the request signal (132).
  8. System (100) according to one of the preceding claims, wherein the additional device (150) is designed as a transceiver (151, 152) comprising the transmitting unit (151, 152, 170) and the receiving unit (151, 152, 180, 182), and the additional signal (160, 161) sent by the transceiver (151, 152) is either a non-modulated signal in a frequency band of the request signal (132) or a modulated signal at a frequency outside the frequency band of the request signal (132).
  9. System (100) according to one of the preceding claims, wherein the additional equipment (150) comprises at least two transceivers (151, 152) which each have a transmitting unit (151, 152, 170) and a receiving unit (151, 152, 180, 182), and the respective transmitting unit (151, 152) of the transceiver (151, 152) sends a respective additional signal (160, 161) as a non-modulated signal outside a frequency band of the request signal (132).
  10. System (100) according to any one of claims 1 to 8, wherein the additional equipment (150) comprises a transceiver (151) which includes the transmitting unit (151, 152, 170) and the receiving unit (151, 152, 180, 182), and the transmitting unit (151, 152, 170) sends at least two additional signals (160, 161) as non-modulated signals.
  11. System (100) according to one of the preceding claims, wherein the transmitting unit (151, 152, 170) sends at least one additional signal (160, 161) for the application of a frequency hopping method.
  12. System (100) according to any one of claims 1 to 7, wherein the transmitting unit (170) and the receiving unit (180) of the additional device (150) are arranged spatially separate from each other.
  13. System (100) according to one of claims 1 to 7 or 12, wherein the additional device (150) comprises a transmitting unit (170) and two receiving units (180, 182) and the transmitting unit (170) is spatially separated from the two receiving units (180, 182).
  14. Method for locating an RFID transponder (120) in relation to an RFID reader (110) in an RFID system (100), wherein the method comprises: the RFID reader (110) sends out a request signal (132) at a predetermined frequency, the RFID transponder (120) receives the request signal (132) and sends a response signal back to the RFID reader (110), at least one transmitting unit (151, 152, 170) of an auxiliary device (150) emits at least one additional signal (160, 161) which differs from the request signal (132) with respect to frequency, and at least one receiving unit (151, 152, 180, 182) of the auxiliary device (150) detects at least one detection signal (162, 163) which generated by an interaction of at least one additional signal (160, 161) with the RFID transponder (120), and Based on the detection signal (162, 163) at least one piece of information for the localization of the RFID transponder (120) in relation to the RFID reader (110) is determined.
  15. The method of claim 14, further comprising: the transmitting unit (151, 152, 170) emits at least two additional signals (160, 161) which each differ from the request signal (132) with respect to frequency, the receiving unit (151, 152, 180, 182) detects at least two detection signals (162, 163) at the respective frequency of the at least two additional signals (160, 161), a distance (d), a direction of movement and a speed of the RFID transponder (120) relative to the RFID reader (110) are determined using at least two detection signals (162, 163), particularly the two additional signals (160, 161) are sent by two different transmitting units (151, 152) which have a predetermined spatial distance (a) between them, and an angle of the RFID transponder (120) relative to a predetermined direction is determined based on at least two detection signals (162, 163) and on the predetermined spatial distance (a).

Description

The invention relates to an RFID system (RFID stands for radio frequency identification), i.e., an identification system that operates in the radio frequency range. The RFID system comprises an RFID reader that transmits a request signal at a specific frequency and an RFID transponder that receives the request signal and sends a response signal back to the RFID reader. The RFID transponder is also known as an RFID tag or RFID responder. Since RFID transponders typically do not have a power source such as a battery, the signal received by the RFID reader serves two purposes: firstly, to power the RFID transponder and essentially wake up its electronic components, and secondly, to request a response signal from the RFID transponder, which a transmitter on the RFID transponder then sends back to the RFID reader for identification. RFID readers now have a relatively large "reading range," meaning a relatively long distance for communication with one or more RFID transponders. For example, the range of an RFID reader is 8 to 10 meters when capacitive coupling is used between the RFID reader and the RFID transponder. However, such a range of the RFID reader means that within the reading range of the RFID reader, a received response signal cannot be assigned to the position of a specific RFID transponder. If several RFID transponders are located within the reading range, it cannot be clearly determined whether communication between the RFID reader and a desired transponder is taking place. RFID transponder or with another RFID transponder that happens to be within the reading range of the RFID reader. Since RFID systems are used in many technical fields, it would be advantageous for many RFID applications to determine the position of one or more RFID transponders, or at least their direction of movement relative to the RFID reader, within the reading range of the RFID device. While several methods are known that allow at least an estimation of the distance of an RFID transponder relative to an RFID reader, these known methods either have limited accuracy or require considerable effort to determine the distance of an RFID transponder relative to the RFID reader. One object of the invention is to provide an RFID system and a method for operating such a system that enables the localization of an RFID transponder with minimal effort. This problem is solved by a system and a method with the features of the independent claims. Advantageous embodiments of the invention are specified in the dependent claims, the description, and the drawings. The system according to the invention is designed for locating a transponder intended for identification in the radio frequency range (RFID transponder) with respect to an RFID reader. The system therefore comprises the RFID reader, which transmits a request signal at a predetermined frequency, and the RFID transponder, which receives the request signal and sends a response signal back to the RFID reader. Furthermore, the system includes an auxiliary device with at least one transmitter unit and at least one receiver unit. The transmitter unit sends at least one additional signal that differs from the request signal of the RFID reader with respect to the Frequency is distinguished. The receiving unit detects at least one detection signal, which is generated by an interaction of the additional signal with the RFID transponder. Furthermore, the additional device is designed to use the detection signal to determine at least one piece of information for locating the RFID transponder in relation to the RFID reader. The system is therefore designed for communication between the RFID reader and the RFID transponder, whereby the RFID reader sends the request signal at a predetermined frequency, and the RFID transponder sends back the response signal, which can be received by the RFID reader. The predetermined frequency lies, for example, in the ultra-high frequency RFID (UHF RFID) band between approximately 850 and 950 MHz. This also applies to the response signal of the RFID transponder. When the RFID transponder responds to the request from the RFID reader and sends the response signal as a modulated signal, the RFID transponder modulates its backscatter cross-section. This change in the backscatter cross-section of the RFID transponder is caused, for example, by changing the impedance at an antenna port of the RFID transponder to modulate the response signal. The change or modulation of the RFID transponder's backscatter cross-section is independent of the frequency of the signals reaching the RFID transponder. This means that the modulation of the RFID transponder's backscatter cross-section, caused by sending the response signal, is detectable over a wide frequency band and not only at the predetermined frequency and the frequency of the response signal. The modulation of the backscatter cross-section of the RFID transponder therefore also affects the auxiliary signal and the detectio