RFID TAG MOVEMENT DISTINGUISHING METHOD AND RFID TAG MOVEMENT DISTINGUISHING PROGRAM

• US 20140167920A1
• Filed: 07/12/2012
• Published: 06/19/2014
• Est. Priority Date: 07/12/2011
• Status: Active Grant

• Current Assignee: Mighty Cube Co., Ltd.
• Original Assignee: Mighty Card Corporation (Takachiho Koheki Co., Ltd.)
• Inventors: Kamiya, Hajime
• Granted Patent: US 9,460,327 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: G01S 13/505 using Doppler effect for determining closest range to a target or corresponding time, e.g. miss-distance indicator
• CPC Class Codes: G01S 13/52 Discriminating between fixed and moving objects or between objects moving at different speeds
• CPC Class Codes: G01S 13/58 Velocity or trajectory determination systems; Sense-of-movement determination systems
• CPC Class Codes: G01S 13/76 wherein pulse-type signals are transmitted
• CPC Class Codes: G01S 13/78 discriminating between different kinds of targets, e.g. IFF-radar, i.e. identification of friend or foe G01S13/75, G01S13/79 take precedence
• CPC Class Codes: G06K 7/10366 the interrogation device being adapted for miscellaneous applications

Abstract

Provided are an RFID tag movement distinguishing method and an RFID tag movement distinguishing program with which are an RFID tag that has moved in front of an antenna and an RFID tag that is static are identified. Chronological read data of RFID tags including a moving RFID tag and a static RFID tag is acquired by an RFID reader, and the static RFID tag is specified by a static RFID tag filter based on information of read RFID tags. In the RFID tag movement distinguishing method, the static RFID tag filter identifies the moving RFID tag by identifying the static RFID tag and the moving RFID tag using an individual static RFID tag filter among a quick-read filter, an RSSI absolute value filter, an RSSI non-contiguous increase filter, an RSSI valley-shaped filter, an excess read filter, a phase shift reduction filter, and a vertical direction movement filter.

Claims

1. An RFID tag movement distinguishing method of identifying a moving RFID tag among a plurality of RFID tags using the plurality of RFID tags and an RFID reader that receives radio waves from the plurality of RFID tags,

wherein the RFID reader is configured to acquire chronological read data of the plurality of RFID tags including a moving RFID tag and a static RFID tag, and a static RFID tag filter is configured based on a certain parameter to specify the static RFID tag based on information of the plurality of read RFID tags, and the moving RFID tag among the plurality of RFID tags is distinguished,

the static RFID tag filter includes an individual static RFID tag filter including any one of the following steps (1) to (6), and

the static RFID tag filter identifies the moving RFID tag by identifying the static RFID tag and the moving RFID tag using at least one or more of a plurality of individual static RFID tag filters,

the RFID tag movement distinguishing method, comprising:

(1) calculating the number of possible readings per second using a function having the number of tags being read as a variable, and performing identification based on a comparison with the number of readings per second read by the RFID reader;

(2) identifying the static RFID tag and the moving RFID tag by chronological analysis of received radio wave strength;

(3) tracing up to a predetermined chronological data and determining whether there is another point having high received radio wave strength when chronological data of received radio wave strength of an RFID tag read by the RFID reader has a valley shape, that is, when a point having high received radio wave strength occurs, and identifying an RFID tag to be the static RFID tag when there is a point having high received radio wave strength;

(4) identifying the static RFID tag and the moving RFID tag using at least one of a degree in which an overall mountain shape represented by the chronological data of the received radio wave strength of the RFID tag or a rising portion of the mountain shape is fit into as a linear or non-linear curve, a difference between each maximum strength value and a minimum strength value of the mountain shape, and a rate of a point increased from a previous point in chronological order in the mountain shape;

(5) identifying the static RFID tag and the moving RFID tag by chronological analysis of a phase of a transmission carrier wave of the RFID reader and a carrier wave reflected and returned from an RFID tag; and

(6) identifying a moving direction by comparing either of a phase inflection point of an RFID tag response and a point at which a frequency is zero (0) with at point at which a received radio wave strength peak occurs.

2. The RFID tag movement distinguishing method according to claim 1,

wherein the function having the number of tags being read as a variable in the step (1) is a power curve function or a polynomial function having the number of tags being read as an independent variable, a threshold value obtained by multiplying a calculation value calculated using the function by a predetermined rate is used as a determination criterion, and an RFID tag is identified as the static RFID tag when the number of readings per second is smaller than the determination criterion.

3. The RFID tag movement distinguishing method according to claim 1,

wherein horizontal direction movement nearby an antenna is detected using various kinds of the RFID tag filters, but horizontal direction movement or vertical direction movement that is performed far from the antenna is not detected.

4. The RFID tag movement distinguishing method according to claim 1,

wherein in the chronological analysis in the step (5), the RFID tag movement distinguishing method further comprises identifying the static RFID tag and the moving RFID tag by using at least one of setting a threshold value to a standard deviation value of a phase, a binomial test, a chi-squared test, and a G test, and

5. The RFID tag movement distinguishing method according to claim 1,

wherein for the certain parameter, as a start point and an end point at the time of movement are selected after moving an experimental RFID tag in advance, the parameter in which an environmental difference such as a RFID reader, an antenna, a tag, or a moving velocity is absorbed is automatically calculated.

6. A non-transitory computer readable medium including one or more computer executable instructions that cause a computer to:

acquire chronological read data obtained by reading a plurality of RFID tags including a moving RFID tag and a static RFID tag through an RFID reader,

specify the static RFID tag based on information of the plurality of RFID tags through a static RFID tag filter configured based on a certain parameter, and

identify the moving RFID tag among the plurality of RFID tags, and to execute, in an arbitrary order, an individual static RFID tag filter including at least one or more of;

(1) calculating the number of possible readings per second using a function having the number of tags being read as a variable, and performing identification based on a comparison with the number of readings per second read by the RFID reader;

(2) identifying the static RFID tag and the moving RFID tag by chronological analysis of received radio wave strength;

(3) tracing up to certain chronological data and determining whether there is another point having high received radio wave strength when chronological data of received radio wave strength of an RFID tag read by the RFID reader has a valley shape, that is, when a point having high received radio wave strength occurs, and identifying an RFID tag to be the static RFID tag when there is a point having high received radio wave strength;

(4) identifying the static RFID tag and the moving RFID tag using at least one of a degree in which an overall mountain shape represented by the chronological data of the received radio wave strength of the RFID tag or a rising portion of the mountain shape is fit into as a linear or non-linear curve, a difference between each maximum strength value and a minimum value of the mountain shape, and a rate of a point increased from a previous point in chronological order in the mountain shape;

(5) identifying the static RFID tag and the moving RFID tag by chronological analysis of a phase of a transmission carrier wave of the RFID reader and a carrier wave reflected and returned from an RFID tag; and

(6) identifying a moving direction by comparing either of a phase inflection point of an RFID tag response and a point at which a frequency is zero (0) with at point at which a received radio wave strength peak occurs.