Inventory-cycle-based RFID tag location

Patent metadata

Field	Value
Publication number	US-9852319-B1
Application number	US-201615201231-A
Country	US
Kind code	B1
Filing date	Jul 1, 2016
Priority date	Jul 2, 2015
Publication date	Dec 26, 2017
Grant date	Dec 26, 2017

Abstract

Techniques are provided to estimate the location of an RFID tag using tag read information, such as a tag read count or a tag read rate, and an opportunity metric, such as an inventory cycle duration, inventory cycle rate, or inventory cycle count. A tag tracking system determines read information for a tag in a zone and an opportunity metric associated with the tag and the zone. The tag tracking system then computes a success rate based on the tag read information and opportunity metric, and uses the success rate to estimate the location of the tag.

First claim

We claim:

1. A method for a Radio Frequency Identification (RFID) system to estimate a location of an RFID tag, the method comprising:
transmitting a first inventorying RF wave to a first zone;
counting a first nonzero number of responses from the RFID tag in the first zone;
determining a first success rate based on the first nonzero response count and a first opportunity metric associated with the first zone;
transmitting a second inventorying RF wave to a second zone different from but overlapping the first zone;
counting a second nonzero number of responses from the RFID tag in the second zone;
determining a second success rate based on the second nonzero response count and a second opportunity metric associated with the second zone; and
estimating the tag location within an overlapping portion of the first and second zones based at least on a comparison of the first and second success rates.

2. The method of claim 1 , wherein:
counting the first and second nonzero numbers of responses of the RFID tag includes counting over first and second time intervals, respectively; and
the first and second opportunity metrics are based on the first and second time intervals, respectively.

3. The method of claim 1 , wherein the first opportunity metric is based on at least one of:
a number of inventory cycles performed while transmitting the first inventorying RF wave to the first zone; and
a total number of RFID tags inventoried in the first zone.

4. The method of claim 1 , wherein the first opportunity metric is one of an inventory-cycle duration and an inventory-cycle rate.

5. The method of claim 1 , further comprising using at least one of a weighted-averaging method and a centroid-averaging method to estimate the tag location.

6. The method of claim 1 , further comprising estimating the tag location based on the comparison and at least one of:
a received signal strength indicator (RSSI) associated with a response from the RFID tag,
an angle-of-arrival of the response,
a phase of the response,
a Doppler parameter of the response,
a timing of the response, and
data included in the response.

7. The method of claim 1 , wherein the RFID system includes a synthesized-beam reader (SBR) and the first zone is an SBR beam.

Assignees

• Impinj Inc

Inventors

• Pesavento Alberto
• Anderl Thomas
• Ascani Robert J

Classifications

• G06Q10/087

  Inventory or stock management, e.g. order filling, procurement or balancing against orders · CPC title

• G06K19/07749

  the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card · CPC title

• G06K7/10366 Primary

  the interrogation device being adapted for miscellaneous applications · CPC title

• G06K7/10178

  including auxiliary means for focusing, repeating or boosting the electromagnetic interrogation field (comparable booster antennas integrated on the record carrier itself G06K19/07794) · CPC title

• G06K7/10128 Primary

  the step consisting of detection of the presence of one or more record carriers in the vicinity of the interrogation device · CPC title