SYSTEMS AND METHODS TO DETERMINE MOTION PARAMETERS USING RFID TAGS

• US 20140104042A1
• Filed: 12/18/2013
• Published: 04/17/2014
• Est. Priority Date: 06/05/2008
• Status: Active Grant

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Micron Technology, Inc.
• Inventors: Tuttle, John R.
• Granted Patent: US 9,477,863 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• 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 system, comprising:

a plurality of devices disposed in a field, each respective device in the plurality of devices having a memory to store an identifier to uniquely identify the respective device among the plurality of devices, the respective device configured to selectively respond to radio frequency signals broadcast to the field based on the identifier stored in the memory and commands modulated on the radio frequency signals; and

a reader configured to transmit at least one first radio frequency signal to the plurality of devices to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal, the reader is further configured to transmit the subsequent radio frequency signal in response to which the first device having the first identifier is configured to provide at least one second radio frequency signal;

wherein the reader comprises a data processing system configured to determine a motion of the first device, based on a Doppler frequency shift detected in the at least one second radio frequency signal.

2. The system of claim 1, wherein the reader further comprises:

a first antenna configured to receive a first signal of the at least one second radio frequency signal at a first location; and

a second antenna configured to receive a second signal of the at least one second radio frequency signal at a second location;

wherein the reader is configured to determine a frequency difference between the first signal received at the first antenna and the second signal received at the second antenna and to determine the Doppler frequency shift from the frequency difference.

3. The system of claim 1, wherein the first device is configured to modulate data on the subsequent radio frequency signal.

4. The system of claim 3, wherein the reader is configured to normalize the at least one second radio frequency signal to detect the Doppler frequency shift.

5. A method, comprising:

transmitting at least one first radio frequency signal to a plurality of devices positioned in a field, wherein the at least one first radio frequency signal is configured to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal;

transmitting the subsequent radio frequency signal to the field;

receiving, from the first device having the first identifier, at least one second radio frequency signal that is responsive to the subsequent radio frequency signal;

determining a Doppler frequency shift in the at least one second radio frequency signal; and

identifying a motion of the first device, based on the Doppler frequency shift.

6. The method of claim 5, wherein the receiving of the at least one second radio frequency signal includes receiving a first signal using a first antenna and receiving a second signal using a second antenna;

and the method further comprises;

determining a frequency difference between the first signal received via the first antenna and the second signal received at the second antenna;

wherein the Doppler frequency shift is determined based on the frequency difference.

7. The method of claim 6, wherein the motion of the first device is identified based on position, speed, acceleration or jerk.

8. The method of claim 6, wherein the at least one second radio frequency signal is actively transmitted from the first device.

9. The method of claim 6, wherein the at least one first radio frequency signal instructs the first device to increase backscatter of the subsequent radio frequency signal and the second devices to decrease backscatter of the subsequent radio frequency signal, for a duration of the transmission of the subsequent radio frequency signal.

10. The method of claim 5, wherein the receiving of the at least one second radio frequency signal includes receiving a first signal using a first antenna and receiving a second signal using a second antenna;

and the first device is positioned between the first antenna and the second antenna.

11. The method of claim 10, wherein the first antenna and the second antenna are positioned on a line of motion of the first device.

12. The method of claim 5, further comprising:

detecting presence of the first device at a first location; and

determining presence of the first device at a second location based on the first location and the motion identified using the Doppler frequency shift.

13. The method of claim 12, further comprising:

determining a direction of the motion based on a strength of the at least one second radio frequency signal.

14. The method of claim 5, wherein the at least one second radio frequency signal is received from the first device in response to the subsequent radio frequency signal interrogating the first device.

15. The method of claim 14, wherein the receiving of the at least one second radio frequency signal from the first device comprises:

maintaining transmission of the subsequent radio frequency signal for a period of time.

16. The method of claim 15, further comprising:

removing data modulation from the at least one second radio frequency signal to determine the Doppler frequency shift.

17. The method of claim 16, wherein the data modulation is removed via normalization.

18. The method of claim 16, wherein the first device is configured to modulate data on the subsequent radio frequency signal.

19. A reader, comprising:

a signal generator configured to generate radio frequency signals to a plurality of devices positioned in a field;

at least one transceiver coupled with the signal generator to transmit at least one first radio frequency signal to the plurality of devices to request a first device having a first identifier in the plurality of devices to response to a subsequent radio frequency signal and to request second devices having second identifiers different from the first identifier in the plurality of devices to generate no response to the subsequent radio frequency signal;

a plurality of antennas configured to receive, from the first device that has the first identifier, a plurality of signals responsive to the subsequent radio frequency signal;

a processor coupled with the at least one transceiver to determine a motion of the first device, based on a Doppler frequency shift detected from the plurality of signals responsive to the subsequent radio frequency signal.

20. The reader of claim 19, wherein the processor is configured to determine a frequency difference between the plurality of signals responsive to the subsequent radio frequency signal.