RFID-based item presence detection
AssigneeImpinj, Inc.
InventorsBalaji Shyamkumar, Kurt Sundstrom, Scott Cooper, Jayasuryan Iyer, Sandesh Doddameti, Christopher J. Diorio
Life of this patent
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Abstract
An RFID-based item tracking system may use statistical methods to determine whether a tag or tagged item that does not respond when inventoried is present in a particular zone or reader antenna field-of-view. In one embodiment, the item tracking system may determine an observability of an item based on one or more initial trials. Upon not detecting the item in one or more subsequent trials, the item tracking system may estimate whether the item is still present based on the observability.
Claims20
A method for a system that includes at least a Radio Frequency Identification (RFID) reader system and a processor block to estimate whether an item is in a zone, the method comprising:
- in at least one initial trial, the RFID reader system receiving an identifier from the item in the zone;
- the processor block determining, based on at least the identifier received in the at least one initial trial, an observability of the item in the zone;
- in a first subsequent trial, the RFID reader system attempting to receive the identifier from the item in the zone;
- and
- upon the RFID reader system failing to receive the identifier in the first subsequent trial, the processor block determining a presence probability of the item in the zone based on the observability and the failure of the first subsequent trial.
A system configured to estimate the presence of an item in a zone, the system comprising:
- a reader system configured to:
- in at least one initial trial, receive an identifier from the item in the zone;
- and
- in a first subsequent trial:
- attempt to receive the identifier from within the zone;
- and
- fail to receive the identifier;
- and
- a processor block configured to:
- determine, based on the at least one initial trial, an observability of the item in the zone;
- and
- in response to the reader system failing to receive the identifier in the first subsequent trial, determine a presence probability of the item in the zone based on the observability and the failure of the first subsequent trial.
A system configured to estimate the presence of an item, the system comprising:
- a synthesized-beam reader (SBR) system configured to:
- generate a first beam corresponding to a first zone;
- in at least one initial trial, receive an identifier for the item on the first beam;
- and
- in a first subsequent trial:
- attempt to receive the identifier on the first beam;
- and
- fail to receive the identifier;
- and
- a processor block configured to:
- determine, based on the at least one initial trial, an observability of the item;
- in response to the reader system failing to receive the identifier in the first subsequent trial, determine a presence probability of the item based on the observability and the failure of the first subsequent trial;
- and
- estimate, based on the presence probability and a presence threshold, whether the item is still in the first zone.
Dependencies are inferred from the claim text.