Systems and methods to determine kinematical parameters
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 circuitry to transmit an interrogating electromagnetic wave according to an interrogating signal having a predetermined frequency;
a receiver circuitry 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; and
compute a position or speed of the radio frequency device based at least in part on a characteristic parameter of the combined signal;
wherein the characteristic parameter, based on which the position or speed of the radio frequency device is computed, is based on a time duration of a number of characteristic points in the combined signal.
2. The reader of claim 1 , wherein the processor is configured to measure the characteristic parameter of the combined signal from a profile of the combined signal.
3. The reader of claim 2 , wherein the received signal is a backscattered version of the interrogating electromagnetic wave from backscattering.
4. The reader of claim 2 , wherein the processor is configured to generate the combined signal 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 processor is configured to generate the combined signal 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 the number of characteristic points in the profile of the combined signal; and
determine the time duration between a beginning one of the characteristic points and an ending one of the 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 circuitry to transmit an interrogating electromagnetic wave according to an interrogating signal having a predetermined frequency;
a receiver circuitry 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; and
compute a position or speed of the radio frequency device based at least in part on a characteristic parameter of the combined signal;
wherein the characteristic parameter, based on which the position or speed of the radio frequency device is computed, is based on a time duration of a number of characteristic points in the combined signal.
11. The system of claim 10 , further configured to measure the characteristic parameter of the combined signal from a profile of the combined signal.
12. The system of claim 11 , wherein the received signal includes a backscattered version of the interrogating electromagnetic wave.
13. The system of claim 11 , further configured to generate the combined signal 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 , further comprising:
a digital processing unit configured to:
count the 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 the time duration between a beginning one of the characteristic points and an ending one of the characteristic points.
15. The system of claim 14 , further comprising:
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; and
computing a position or speed of the radio frequency device based at least in part on a characteristic parameter of the combined signal;
wherein the characteristic parameter, based on which the position or speed of the radio frequency device is computed, is based on a time duration of a number of characteristic points in the combined signal.
17. The method of claim 16 , further comprising:
measuring the characteristic parameter of the combined signal from a profile of the combined signal.
18. The method of claim 17 , wherein the received signal includes a backscattered version of the interrogating electromagnetic wave.
19. The method of claim 17 , wherein the combining to generate the combined signal includes 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 combining to generate the combined signal includes mixing the portion of the interrogating signal having the predetermined frequency with the portion of the received signal.