Systems and Methods to Determine Motion Parameters using RFID Tags

• US 20090303004A1
• Filed: 06/05/2008
• Published: 12/10/2009
• Est. Priority Date: 06/05/2008
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Keystone Technology Solutions, LLC
• Inventors: TUTTLE, John R.
• Granted Patent: US 8,242,888 B2
• Time in Patent Office: Days
• US Class Current: 340/10.100
• CPC Class Codes: G01S 11/10 using Doppler effect
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10019 resolving collision on the communication channels between simultaneously or concurrently interrogated record carriers. collision between the communication channels used by wireless communication devices, where the solution is not particularly adapted for RFIDs or the like, H04W74/08
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10366 the interrogation device being adapted for miscellaneous applications
• CPC Class Codes: H04Q 2213/13095 PIN / Access code, authentication

Abstract

Systems and methods to determine motion parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, a method implemented in a radio frequency identification (RFID) system includes determining a motion parameter of the RFID tag based on detecting a Doppler frequency shift in a radio frequency signal received from the RFID tag.

Claims

1. A method implemented in a radio frequency identification (RFID) system, the method comprising:

an RFID reader interrogating an RFID tag via radio frequency electromagnetic waves;

receiving at least one radio frequency signal from the RFID tag;

detecting a Doppler frequency shift in the radio frequency signal received from the RFID tag; and

calculating a motion parameter of the RFID tag, based on the Doppler frequency shift detected in the at least one radio frequency signal received from the RFID tag.

2. The method of claim 1, wherein the motion parameter comprises position, speed, acceleration or jerk.

3. The method of claim 1, wherein the receiving of the at least one radio frequency signal comprises receiving a first signal at a first antenna and a second signal at a second antenna;

and the method further comprises;

determining a frequency difference between the first signal and the second signal to detect the Doppler frequency shift.

4. The method of claim 3, further comprising the RFID tag transmitting a radio frequency electromagnetic wave independent of electromagnetic waves from the RFID reader;

wherein the radio frequency electromagnetic wave is received as the first signal at the first antenna and the second signal at the second antenna.

5. The method of claim 3, further comprising the RFID tag reflecting an interrogating electromagnetic wave from the first antenna to provide the first signal and reflecting an interrogating electromagnetic wave from the second antenna to provide the second signal.

6. The method of claim 3, wherein in response to a command from the RFID reader, the RFID tag reflects a radio frequency electromagnetic wave transmitted from the RFID reader to generate a backscattered wave which is received as the first signal at the first antenna and the second signal at the second antenna.

7. The method of claim 1, wherein the radio frequency signal is received from the RFID tag in response to the RFID reader interrogating the RFID tag.

8. The method of claim 7, wherein the radio frequency signal is received from the RFID tag in response to the RFID reader interrogating a plurality of RFID tags, including the RFID tag.

9. The method of claim 8, wherein the RFID reader communicating with the plurality of RFID tags to silent the plurality of RFID tags except the RFID tag to receive the radio frequency signal.

10. The method of claim 1, wherein the receiving of the radio frequency signal from the RFID tag comprises:

the RFID reader maintaining transmission of an interrogating electromagnetic wave for a period of time;

the RFID tag operating in a mode of increased backscatter of the interrogating electromagnetic wave; and

the RFID reader receiving the interrogating electromagnetic wave backscattered from the RFID tag.

11. The method of claim 10, wherein the determining of the motion parameter of the RFID tag comprises:

combining the interrogating electromagnetic wave transmitted by the RFID reader and the interrogating electromagnetic wave backscattered from the RFID tag to generate a combined signal; and

determining a frequency of the combined signal to detect the Doppler frequency shift.

12. The method of claim 11, wherein the combining the interrogating electromagnetic wave transmitted by the RFID reader and the interrogating electromagnetic wave backscattered from the RFID tag comprises:

summing the interrogating electromagnetic wave transmitted by the RFID reader and the interrogating electromagnetic wave backscattered from the RFID tag, mixing the interrogating electromagnetic wave transmitted by the RFID reader and the interrogating electromagnetic wave backscattered from the RFID tag, or determining exclusive OR between the interrogating electromagnetic wave transmitted by the RFID reader and the interrogating electromagnetic wave backscattered from the RFID tag.

13. A radio frequency identification (RFID) system, comprising:

an RFID tag; and

an RFID reader within a radio communication range from the RFID tag, the RFID reader to identify the RFID tag using an interrogating electromagnetic wave transmitted from the RFID reader and to receive at least one radio frequency signal from the RFID tag during interrogation of the RFID tag, the RFID reader to determine a Doppler frequency shift in the received radio frequency signal and calculate a motion parameter of the RFID tag based on the determined Doppler frequency shift.

14. The radio frequency identification (RFID) system of claim 13, wherein the RFID tag is instructed by the RFID reader to operate in a mode of increased backscatter of the interrogating electromagnetic wave;

the RFID reader is to maintain transmission of the interrogating electromagnetic wave for a period of time, to receive the interrogating electromagnetic wave backscattered from the RFID tag to determine the Doppler frequency shift.

15. The radio frequency identification (RFID) system of claim 14, wherein the RFID tag comprises a transceiver circuit to reflect the interrogating electromagnetic wave at a frequency having a predetermine relation with a frequency of the interrogating electromagnetic wave received at the RFID tag.

16. The radio frequency identification (RFID) system of claim 15, wherein the transceiver circuit comprises a diode coupled to an antenna of the RFID tag to reflect the interrogating electromagnetic wave at a frequency that is twice the frequency of the interrogating electromagnetic wave received at the RFID tag.

17. The radio frequency identification (RFID) system of claim 13, wherein the RFID reader comprises a plurality of antennas to receive a plurality of signals from the RFID tag;

and

the RFID reader is to combine the plurality of antenna signals to detect the Doppler frequency shift.

18. A radio frequency identification (RFID) reader, comprising:

an oscillator to generate an interrogating electromagnetic wave;

at least one antenna and a transceiver coupled to the oscillator to transmit the interrogating electromagnetic wave and to receive at least one radio frequency signal from an RFID tag; and

a processor coupled to the memory and transceiver to identify the RFID tag and to determine a speed of the RFID tag from a Doppler frequency shift in the radio frequency signal received from the RFID tag.

19. The radio frequency identification (RFID) reader of claim 18, wherein the processor is to combine the radio frequency signal received from the RFID tag with a signal from the oscillator to detect the Doppler frequency shift.

20. The radio frequency identification (RFID) reader of claim 18, wherein the at least one antenna includes a plurality of antennas to receive a plurality of radio frequency signals;

and the processor is to combine the plurality of radio frequency signals received from the RFID tag to detect the Doppler frequency shift.

21. A radio frequency identification (RFID) tag, comprising:

a memory to store an identification number of the tag; and

an antenna;

a transceiver coupled to the antenna;

a controller coupled to the memory and the transceiver, the controller being capable to modulate a radio frequency signal transmitted via the antenna to provide the identification number of the tag;

wherein, in response to a request received via the antenna, the controller is to transmit a radio frequency electromagnetic wave for a period of time without modulating information on the electromagnetic wave.

22. The radio frequency identification (RFID) tag of claim 21, wherein in response to the request, the controller is to maintain the antenna in a reflective mode to backscatter an interrogating electromagnetic wave for a predetermined period of time without modulating data on the backscattered wave.

23. The radio frequency identification (RFID) tag of claim 21, wherein in response to the request, the controller is to generate and transmit a signal of a predetermined frequency until a subsequent command is received.

24. A machine readable media embodying instructions, the instructions causing a radio frequency identification (RFID) system to perform a method, the method comprising:

an RFID reader interrogating an RFID tag via radio frequency electromagnetic waves;

receiving at least one radio frequency signal from the RFID tag;

detecting a Doppler frequency shift in the radio frequency signal received from the RFID tag; and

calculating a motion parameter of the RFID tag, based on the Doppler frequency shift detected in the at least one radio frequency signal received from the RFID tag.