Systems and methods to determine kinematical parameters using RFID tags
View Patent ↗Systems and methods to determine kinematical parameters of physical objects using radio frequency identification (RFID) tags attached to the objects. In one embodiment, one of a population of RFID tags is selectively instructed by an RFID reader to backscatter the interrogating electromagnetic wave and thus allow the RFID reader to measure the position, speed, acceleration, and/or jerk of the object to which the tag is attached. The RFID reader combines the signal representing the backscattered interrogating electromagnetic wave and the signal representing the interrogating electromagnetic wave transmitted by the RFID reader to determine or monitor one or more of the kinematical parameters of the object.
1. A reader, comprising:
an antenna circuity to transmit an interrogating electromagnetic wave according to an interrogating signal having a predetermined frequency;
a receiver circuity to obtain a received signal generated by a radio frequency device from the interrogating electromagnetic wave, the radio frequency device having an identification; and
a processor coupled to the receiver to:
determine the identification of the radio frequency device from the received signal;
combine a portion of the interrogating signal having the predetermined frequency with a portion of the received signal to generate a combined signal;
measure a characteristic parameter of the combined signal; and
compute a position or speed of the radio frequency device based at least in part on the characteristic parameter of the combined signal.
2. The reader of claim 1 , wherein the characteristic parameter of the combined signal is measured from a profile of the combined signal.
3. The reader of claim 2 , wherein the received signal is generated by the radio frequency device from the interrogating electromagnetic wave from backscattering.
4. The reader of claim 2 , wherein the combined signal is generated by summing the portion of the interrogating signal having the predetermined frequency with the portion of the received signal.
5. The reader of claim 2 , wherein the combined signal is generated by mixing the portion of the interrogating signal having the predetermined frequency with the portion of the received signal.
6. The reader of claim 2 , wherein the processor comprises a digital processing unit configured to:
count a number of characteristic points in the profile of the combined signal; and
determine a time duration between a beginning one of the characteristic points and an ending one of the characteristic points;
wherein the characteristic parameter, based on which the position or speed of the radio frequency device is computed, is the time duration of the number of characteristic points.
7. The reader of claim 6 , wherein the beginning one and the ending one of the characteristic points are two different ones of: minimum, maximum, null and inflection, in the profile of the combined signal.
8. The reader of claim 6 , wherein the processor further comprises:
a low pass filter to generate the profile signal; and
a signal sampler to sample the profile signal.
9. The reader of claim 8 , further comprising:
a normalizer to normalize the received signal for combination with portion of the interrogating signal having the predetermined frequency.
10. A system, comprising:
at least one radio frequency device, the radio frequency device having an identification; and
a reader having:
an antenna circuity to transmit an interrogating electromagnetic wave according to an interrogating signal having a predetermined frequency;
a receiver circuity to obtain a received signal generated by the radio frequency device from the interrogating electromagnetic wave; and
a processor coupled to the receiver to:
determine the identification of the radio frequency device from the received signal;
combine a portion of the interrogating signal having the predetermined frequency with a portion of the received signal to generate a combined signal;
measure a characteristic parameter of the combined signal; and
compute a position or speed of the radio frequency device based at least in part on the characteristic parameter of the combined signal.
11. The system of claim 10 , wherein the characteristic parameter of the combined signal is measured from a profile of the combined signal.
12. The system of claim 11 , wherein the received signal is generated by the radio frequency device from the interrogating electromagnetic wave from backscattering.
13. The system of claim 11 , wherein the combined signal is generated by summing or mixing the portion of the interrogating signal having the predetermined frequency with the portion of the received signal.
14. The system of claim 11 , wherein the processor comprises a digital processing unit configured to:
count a number of characteristic points in the profile of the combined signal, the characteristic points being at least one of: minimum, maximum, null and inflection, in the profile of the combined signal; and
determine a time duration between a beginning one of the characteristic points and an ending one of the characteristic points;
wherein the characteristic parameter, based on which the position or speed of the radio frequency device is computed, is the time duration of the number of characteristic points.
15. The system of claim 14 , wherein the processor further comprises:
a normalizer to normalize the received signal for combination with portion of the interrogating signal having the predetermined frequency;
a low pass filter to generate the profile signal; and
a signal sampler to sample the profile signal.
16. A method, comprising:
transmitting an interrogating electromagnetic wave according to an interrogating signal having a predetermined frequency;
receiving a received signal generated by a radio frequency device from the interrogating electromagnetic wave, the radio frequency device having an identification;
determining the identification of the radio frequency device from the received signal;
combining a portion of the interrogating signal having the predetermined frequency with a portion of the received signal to generate a combined signal;
measuring a characteristic parameter of the combined signal; and
computing a position or speed of the radio frequency device based at least in part on the characteristic parameter of the combined signal.
17. The method of claim 16 , wherein the characteristic parameter of the combined signal is measured from a profile of the combined signal.
18. The method of claim 17 , wherein the received signal is generated by the radio frequency device from the interrogating electromagnetic wave from backscattering.
19. The method of claim 17 , wherein the combined signal is generated by summing the portion of the interrogating signal having the predetermined frequency with the portion of the received signal.
20. The method of claim 17 , wherein the combined signal is generated by mixing the portion of the interrogating signal having the predetermined frequency with the portion of the received signal.