KR101015270B1 - System and method for tracking rfid tag - Google Patents

Abstract

The present invention relates to a trajectory processing system and method of an RFID tag for tracking a movement path of a radio frequency IDentifier (RFID) tag. When an RFID tag moves between a reader and a reader, the traces tracked by each reader are connected to each other. The present invention relates to an RFID tag trajectory processing system and method capable of preventing a disconnection occurring in the trajectory of an RFID tag, and thereby efficiently tracking and managing the trajectory of the RFID tag.

Radio Frequency IDentifier (RFID), RFID Tag, Trajectory, Tracking, TR-tree

Description

Trajectory tracking system and method of RFID tag {SYSTEM AND METHOD FOR TRACKING RFID TAG}

The present invention relates to a trajectory tracking system and method of an RFID tag, and more particularly, to a trajectory tracking system and method of an RFID tag such that the trajectory of an RFID tag is not interrupted between respective RFID readers.

RFID (Radio Frequency IDentifier) system (hereinafter referred to as "RFID") system is a non-contact recognition system that attaches a small chip to various items to transmit and process the information of the object and the surrounding environment information at a radio frequency. In general, RFID systems are readers with read and decryption capabilities (RFID readers, hereinafter abbreviated as "leaders" unless otherwise noted), and RFID tags containing unique information (hereinafter referred to separately). If not, it is abbreviated as "tag"), operating software, network, and the like. An RFID system having such a configuration processes information by identifying a tag attached to an object. The RFID system is a contactless recognition system, and does not need to directly contact the reader and the tag or scan in the visible band. This is because RFID systems use radio frequency identification technology. As a result, the RFID system is evaluated as a technology to replace the bar code, which is a contact recognition system, and the application range of the RFID system is being expanded. For example, the RFID system can be used in various fields such as inventory management, port container management, supply chain management, and dangerous goods management.

One of the main purposes of RFID systems is to tag things and track their movement.

The tracking function of an RFID system is very useful when tracking a product or tracking the movement of an object in a building. In order to track and manage the movement of a tagged object, a trajectory index constituting the tag's past and current movement paths is required.

However, the tag does not have a means for identifying its location. As a result, the tag cannot recognize its own location and time, and the location information and time information of the tag are generated when the tag is read by the reader. That is, the position of the tag is recognized in the same way as the position of the reader where the tag is currently located, and the spatiotemporal information for generating the trajectory index of the tag is obtained from the information of the reader. The trajectory of the moving tag may be expressed in three dimensions having a temporal value and a spatial value acquired from the reader. Due to the characteristics of the RFID system, the position of the tag is recognized as the position of the reader, and the time of the tag is an enter event where the tag enters the reader area and a leave event when the tag exits the reader area. Is generated by Wire these events together to create a time trace parallel to the time axis within a single leader.

However, since the time trajectory of the tag is generated independently in each reader, a trajectory disconnection section in which no tag can be found occurs between the trajectories generated by one reader and the other reader. This disconnection of the time trajectory also affects the formation of the position trajectory of the tag, which makes it difficult to track past trajectories for the tag. Until now, it has been common to use a moving object trajectory management index such as HR-tree (Historical R-tree) and STR-tree (Spatial-Temporal R-tree) for tracking and managing tag trajectories. However, the trajectories of the tags formed by them all have disconnection sections. As mentioned above, such a break of the tag trajectory becomes a factor that makes it difficult to track past trajectories for the tag.

An object of the present invention is to provide a method for tracking a track of an RFID tag that can generate a track of an RFID tag without a disconnection period.

According to an aspect of the present invention, there is provided a track system for tracking a RFID tag, wherein at least one recognizes an identifier and an entry or departure time of an RFID tag entering an area or an RFID tag leaving an area. Receives an RFID reader, an identifier of the RFID tag and an entry time or departure time of the RFID tag from the RFID reader, and the identification information of the RFID reader and the entry time or departure time of the RFID tag. An RFID tag trace tracking device may be configured to update the position information to form a position trace, and to connect the position trace of the RFID tag to a position trace of an RFID reader in which the RFID tag previously existed.

The RFID tag trajectory tracking device includes a database that stores trajectory information for an RFID tag, searches whether there is information of an RFID reader that existed before the RFID tag enters the RFID reader, and uses the search result. The position trajectory of the RFID tag may be connected to the position trajectory of the RFID reader in which the RFID tag previously existed.

의 수학식으로 표현 되는 선들을 모두 연결하여 상기 RFID 태그의 위치 궤적을 형성하며, 상기 수학식의 r은 RFID 리더,

은 RFID 태그가 해당 RFID 리더의 영역을 이탈하는 시각,

는 RFID 태그가 해당 RFID 리더의 영역에 진입하는 시각이다.The RFID tag trajectory tracking device

By connecting all the lines represented by the equation of the position of the RFID tag to form the position, r of the equation r is an RFID reader,

The time at which an RFID tag leaves the area of its RFID reader,

Is the time when the RFID tag enters the area of the RFID reader.

On the other hand, in another aspect of the present invention for achieving the above object, the method for tracking the trajectory of the RFID tag, any RFID reader recognizes the RFID tag entering in its area or the RFID tag leaving from its area and Recognizing an entry time or an departure time of an RFID tag, transmitting, by the reader, an identifier of the entered RFID tag and an entry time or an exit time of the RFID tag to an RFID tag trace tracking device, and tracking an RFID tag trace The device receives an identifier of the RFID tag and an entry time or departure time of the RFID tag from the reader, and the RFID tag is previously transferred using the position information of the RFID reader and the entry time or departure time of the RFID tag. The method may include forming a location trajectory of the RFID tag connected to the location trajectory of the existing RFID reader.

In the step of forming the position trajectory of the RFID tag, an RFID tag trace tracking device that receives the identifier of the RFID tag and the entry time or the departure time of the RFID tag may be used by the RFID reader using the received entry time or the departure time. Forming a position trajectory of the RFID tag of the RFID tag, and wherein the RFID tag trajectory tracking device is present from the own database that stores the trajectory information for the RFID tag before the RFID tag enters the RFID reader. Searching whether information exists and connecting the position trajectory of the RFID tag with the position trajectory in the RFID reader that existed before the RFID reader using the search result.

As described above, the present invention can track the position trajectories of consecutive RFID tags without disconnection and reduce the time required for the position tracking of RFID tags by using TR-tree and TL index in tracking the RFID tags. have.

The present invention configures a complete trajectory for a tag by connecting the trajectories existing in each leader to one space-time line. That is, the present invention proposes a Tag R-tree in RFID system (TR-tree), which is an R-tree-based tag index capable of tracking a past moving path by configuring a Mini Bounding Box (MBB) connecting each dimension in an index. . The proposed index uses the secondary index TL (Tag Link) to guarantee the update performance for frequent tag data movement. TL is a hash index, using all tag IDs as keys. This invention can be achieved in the architecture of the Smart Edge MOnitoring system (SEMO) project.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that detailed descriptions of related known functions or configurations may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a block diagram of a locus tracking system of an RFID tag according to an embodiment of the present invention.

As shown in FIG. 1, the locus tracking system of an RFID tag may be configured to include a tag 100, a reader 110-1 to 110 -N, and an RFID tag locus tracking device 130.

Here, the tag 100 stores information about the object and is attached to the object to be identified. The readers 110-1 to 110 -N identify information on a tag existing in an area of the reader, and transmit the identified information to the RFID tag trajectory tracking device 130. Among the information items of the tag 100 which can be identified by the readers 110-1 to 110 -N, the time when the tag 100 enters the reader's area, and the tag existing in the reader's area is the corresponding reader. The time of departure within the area of, may include the unique information assigned to the tag existing in the area of the reader. The above-described information items are presented to aid the understanding of the present invention, which is not intended to limit the present invention, and various information items may be used for practicing the present invention as necessary.

An enter event occurs when the tag enters the reader area, and a leave event occurs when the tag leaves the area. In this case, the time the tag stays in the reader may be determined by the signals generated, that is, a signal generated at the entry event and a signal generated at the exit event. The spatial position of a tag is the same as that of the leader, and the tag exists in the leader until it leaves the reader.

Each reader 110-1 through 110 -N has a transmitting function and a receiving function for identifying information of a tag and transmitting the identified information. The tag existing in the region of the readers 110-1 to 110 -N refers to a tag that does not leave after entering the region of the corresponding reader. The RFID tag trajectory tracking device 130 generates a trajectory index of the corresponding tag using information of the tags received from the readers 110-1 to 110-N, and tracks the position of the corresponding tag using the generated trajectory index. do.

In FIG. 1, circles 120-1, 120-2, etc. drawn in dotted lines around each of the leaders 110-1 to 110 -N represent an interrogation area of the leader. Ideally, the area of an arbitrary leader will be drawn concentrically with the leader's position as the center point and with the radius of propagation distance from that leader. Of course, in reality, due to various factors such as terrain and radio wave interference, the actual leader area often takes a form different from the ideal area. The shape of the area of the leader is not a limitation of the present invention.

2 is a diagram according to an embodiment of the present invention, which shows an example of movement of an arbitrary RFID tag.

)이고, 태그(100)가 B 지점을 지나는 순간의 시 각이 태그(100)가 리더 1의 영역(120-1)으로부터 이탈하는 시각(

)이다.2 illustrates a case where an arbitrary tag 100 moves through the area 120-1 of the reader 1 110-1. FIG. 2A illustrates a point at which the tag 100 enters the region 120-1 of the reader 1, and FIG. 2B illustrates a point at which the tag 100 leaves the region 120-1 of the reader 1. The time when the tag 100 passes the point A is the time when the tag 100 enters the region 120-1 of the reader 1

), And the time when the tag 100 passes the point B is the time when the tag 100 leaves the area 120-1 of the leader 1 (

)to be.

3 is a block diagram of an RFID reader according to the present invention.

As shown in FIG. 3, the RFID reader may be configured to include a transceiver 300, a controller 310, and a database 320.

The transceiver 300 may recognize an entry or departure of each tag through signal transmission and reception with the tag 100 and obtain an identifier of the corresponding tag 100. In addition, the transmitter / receiver 300 transmits the information about the tag that has entered or exited through the transmission and reception with the RFID tag trace tracking device 130 to the RFID tag trace tracking device 130. The controller 310 checks the entry time or the departure time of the tag that has escaped or entered. The database 320 stores at least information about the tag 100 existing in the area of the RFID reader. The information provided by the reader 110 to the RFID tag trace tracking device 130 may include at least an identifier, an entry time, or a departure time of the tag 100.

4 is a block diagram of an apparatus for tracking a track of an RFID tag according to the present invention.

As illustrated in FIG. 4, the apparatus for tracking a track of an RFID tag may be configured to include a receiver 400, a controller 410, a database 420, and an input / output unit 430.

The receiver 400 receives an identifier of the tag 100 and an entry time or departure time from the reader 110. The controller 410 forms a position trajectory of the corresponding tag 100 using the entry time or departure time of the received tag. In this case, the position trajectory formed is the position trajectory formed by the reader 110 in which the tag 100 currently exists. The control unit 410 forms a continuous position trajectory without disconnection by connecting the formed trajectory with the position trajectory formed by the reader 110 in which the tag 100 previously existed. The database 420 stores data required for the formation of the position trajectory of consecutive tags without disconnection.

FIG. 5 is a diagram illustrating an example of data exchange between an RFID tag, an RFID reader, and an RFID locus tracking device, which are performed in the locus tracking system of the RFID tag shown in FIG. 1.

When the tag 100 enters the area of the reader 110, the tag 100 may receive a signal transmitted by the reader 110 (500). Thereafter, the signal is exchanged between the tag 100 and the reader 110 (502). Through this exchange of signals, the reader 110 recognizes that the tag 100 has entered its area (504). The reader 110 checks the identification information and the entry time of the tag 100 that has entered the area (506). The reader 110 notifies the tag trajectory processing apparatus 130 of the identification information and the entry time of the entered tag 100 (508). The tag trajectory processing unit 130 updates the information of the corresponding tag 100 stored in the database using the information received from the reader 110 (510). On the other hand, if the tag existing in its area is not recognized in its area (520), the reader 110 determines that the corresponding tag 100 has departed from its area, and the departure of the corresponding tag 100 is determined. The tag trace processing apparatus 130 is notified (522). The tag trajectory processing unit 130 updates the information of the corresponding tag 100 stored in the database using the information received from the reader 110.

The information of the tag 100 stored in the database of the tag trajectory processing unit 130 is used as the information for the tag trajectory processing unit 130 to track the trajectory for any tag 100. The tag trajectory processing unit 130 may track the past trajectory for any tag 100 by referring to the information stored in the database.

Hereinafter, the function and operation of the RFID tag trace tracking device 130 will be described in detail.

In order to compose the tag movement by index, the tag trajectory existing for each reader must be made as a complete trajectory like the trajectory of the moving object. This section describes the definition and representation of tag trajectories.

In an RFID system, tags move between readers, and an enter and leave signal is transmitted to the RFID middleware through the reader. 3D information of (x, y, t) is required to configure the tag trajectory at the application level, which is determined by the reader's position and the time of visit.

The leader's trajectory appears parallel to the time axis within each leader. This is because the trajectory is formed based on the time when the reader recognizes the tag and leaves. In other words, the moving object constructs the trajectory by connecting the elapsed time according to the position with a continuous line, but the tag appears as an independent trajectory in each leader.

이다. 여기서, r_i.t_l이 의미하는 것은, r_i번째 RFID 리더를 이탈하는 이탈시각을 나타내는 것이고, r_i+1.t_e가 의미하는 것은 r_i+1번째 RFID 리더를 진입하는 진입시각을 나타내는 것으로서, 상기 식을 풀어서 다시 쓴다면 '(r_i번째 RFID 리더를 이탈하는 이탈시각(t_l)) < (r_i+1번째 RFID 리더를 진입하는 진입시각(t_e))이 됨을 알 수 있다. 따라서, 이 리더번호와 시간들을 모두 연결하면 태그의 이동경로가 완전한 궤적으로 된다.
여기서, r은 RFID 리더, r_i 는 태그가 진입하게 되는 임의의(또는 현재) i번 리더(r)에 진입하는 것을 의미하며, r_i+1 은 태그가 i번 리더(r_i)에서 나온 후 다음 리더(r)에 진입하는 것을 의미한다.

은 RFID 태그가 해당 RFID 리더의 영역을 이탈하는 시각,

는 RFID 태그가 해당 RFID 리더의 영역에 진입하는 시각이다.
상기 수식에서 r_i.t_l 은 태그가 진입한 i번 리더(r_i)를 떠날 때의 이탈시간(t_l은 leave time)을 의미한다.
r_i+1.t_e 는 태그가 i번 리더(r_i)를 떠난 후 다음 리더(r)에 들어갈 때의 진입시간(t_e는 enter time)을 의미한다.
그러므로 상기 수식은 하나의 태그가 i번 리더((r_i)에 진입했다가 떠나는 이탈시간

은 동일 태그가 다음번 리더(r_i+1)인 i+1번을 진입하기 위해 들어가는 진입시간

보다 작다 즉, 이후 시간이라는 것을 의미한다.The time trajectory in the readers to which the tag has moved

to be. Here, r _i .t _l means the departure time leaving the r _i th RFID reader, and r _{i + 1} .t _e means the entrance time entering the r _{i + 1} th RFID reader. If the equation is solved and rewritten, it can be seen that ((leave time (t _l ) leaving the r _i th RFID reader) <(r entry time (t _e ) entering the r _{i + 1} th RFID reader)). have. Therefore, if the reader number and times are all connected, the movement path of the tag becomes a complete trajectory.
Here, r is an RFID reader, r _i is to enter any (or present) i reader (r) to enter the tag, r _{i + 1} is a tag from reader _i (r _i ) After that, it means entering the next reader (r).

The time at which an RFID tag leaves the area of its RFID reader,

Is the time when the RFID tag enters the area of the RFID reader.
In the above formula, r _i .t _l denotes a departure time (t _l is leave time) when leaving the reader (r _i ) entered the tag.
r _{i + 1} .t _e means the entry time (t _e is enter time) when the tag enters the next reader r after leaving reader i (r _i ).
Therefore, the above equation shows the departure time when one tag enters and leaves reader i ((r _i )).

Is the entry time for the same tag to enter i + 1, the next reader (r _{i + 1} ).

That means less time since.

라 하자. 이때, 리더에 머물러 있는 태그는 이탈 이벤트가 발생하지 않아서 [

,

,

]의 시간속성을 갖는다.
여기서, 시간속성

(델타 t)는 두 시간 사이의 차이 시간값을 의미하며, 태그가 이전 리더에서 이탈한 시간

과 새로운 리더에 들어갈 때의

와의 차이이다.

(파이)는 값이 없는 것을 의미하는 공집합 기호로서, 현재 리더에 들어온 후 아직 현재 리더를 이탈하지 않았기 때문에 이탈시간(t_l)을 공집합으로 표현한다.
포인트 태그의 궤적은 다음과 같이

을 해당 태그가 속한 MBB의 최대 시간 값으로 정의한다.On the other hand, tags that enter and leave the leader appear as a single point. Point tags that contain only events that have entered the reader and no exit events

Let's do it. In this case, the tag staying in the reader does not have an exit event, so [

,

,

] Has time attribute.
Where time attribute

(Delta t) is the time difference between two hours, and the time when the tag left the previous reader.

And when you enter a new leader

This is the difference from.

(Pi) is an empty set symbol that means no value, and represents the settling time (t _l ) as the empty set since the current leader has not yet left the current leader.
The trajectory of the point tag is

Is defined as the maximum time value of the MBB to which the tag belongs.

=MAX_TIME(MBB)
즉 각 태그가 3차원정보인 위치(X,Y),시간(T)으로 구성되고 이 3차원의 정보를 선으로 연결하여 최소경계사각형인 MBB(Minimum Bounding Box : 최소경계상자의 의미로서, 한 태그가 리더를 돌아다니면서 만들어지는 리더의 위치정보인 (x, y)좌표와 그 위치에 있을 때의 시간(t)을 선으로 연결하여 상자(box)형태로 만드는 것을 의미함. 시간은 진입과 이탈로 구성됨)를 만들게 되고, 궤적인덱스는 계층구조로 된 색인이므로 트리(TREE)구조의 레벨로 구성되어 여러 태그들의 MBB를 감싸고 있는 상위 MBB가 존재하게 되며, 만약, 리더를 이탈하지 않은 새로운 태그(t_l이 없는 상태)가 이 MBB영역으로 들어온다면 해당 태그에 대해 현 MBB의 최대 시간값을 해당 태그의 이탈시간인 t_l로 지정한다.
만약, t_l에 이탈시간을 설정하지 않고 태그를 검색하게 되면 해당 태그는 포인트 태그(T_P)이므로 검색되지 않습니다.
이러한 포인트 태그(point tag)는 리더를 떠날 때야 비로소 궤적으로 표현된다. 그러나 태그가 새로운 리더로 이동한 경우에도 이전 위치와 연결되어야 궤적 구성이 가능하며, 질의 결과에도 포함될 수 있다. 본 발명에서는 포인트 태그의 이탈 시각이 해당 MBB의 최대값으로 조정되기 때문에, MBB는 확장되지 않으며 인덱스에서 상위노드에 영향을 미치지 않는다. 또한 TPIR-tree에서와 같이 태그 검색을 위한 포인트 태그의 시간 확장이 없으므로 검색 연산이 빠르다. 포인트 태그가 리더를 벗어나는 경우 t_l 값은 실제 이탈 이벤트 시각으로 변경되며, 본 발명에서 제안한 2차 인덱스인 Tag Link(TL)을 이용하여 단말노드에 직접 접근하여 수정한다.
상기 2차 인덱스 태그 링크(TL)는 트리 형태의 태그 궤적 색인의 최하위 레벨인 단말노드(leaf node)들에 저장된 각 태그들과 직접 연결되어 있는 또 하나의 색인이고, 상기 TL은 단말노드에 있는 모든 태그들과 직접 연결되어 있으므로 한 태그를 찾을 때 TL을 이용하면 한번에 검색이 가능하며, 상기 TL은 모든 태그를 갖고 있습니다.
그러므로 상기 TL은 궤적 색인이 갖고 있는 모든 태그를 동일하게 갖고 있으므로 한 태그의 위치, 시간정보가 변경된 경우, TL에서 해당 태그를 찾아 궤적 색인의 단말에 직접 접근하여 수정합니다.

= MAX_TIME (MBB)
In other words, each tag is composed of three-dimensional information (X, Y) and time (T), and the three-dimensional information is connected by a line, which is the minimum bounding box MBB (Minimum Bounding Box). It means that the tag forms a box by connecting the (x, y) coordinate, which is the position information of the leader created as it moves around the reader, and the time (t) when it is at that position, with a line. Since the trajectory index is a hierarchical index, there is a parent MBB that is composed of the tree structure level and surrounds the MBBs of several tags. If (t _l is not present) enters this MBB area, the maximum time value of the current MBB for the tag is set as t _l , the departure time of the tag.
If the tag is searched without setting the escape time in t _l , the tag is not searched because it is a point tag (T _P ).
These point tags are only represented as trajectories when they leave the leader. However, even if the tag is moved to a new reader, the trajectory configuration is possible only if it is connected to the previous position and can be included in the query result. In the present invention, since the departure time of the point tag is adjusted to the maximum value of the MBB, the MBB is not extended and does not affect the upper node in the index. Also, as in TPIR-tree, there is no time extension of point tag for tag search, so the search operation is fast. If the point tag leaves the reader, the t _l value is changed to the actual departure event time, and is modified by directly accessing the terminal node using Tag Link (TL), which is the secondary index proposed by the present invention.
The secondary index tag link (TL) is another index directly connected to each tag stored in leaf nodes, which is the lowest level of the tree-shaped tag trajectory index, and the TL is located in the terminal node. Since all tags are directly connected, you can search by using TL when searching for one tag, and the TL has all the tags.
Therefore, the above TL has all the same tags in the trajectory index, so if the position and time information of one tag is changed, find the corresponding tag in the TL and directly access the terminal of the trajectory index and modify it.

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The spatial coordinates of the tag follow the reader position where the entry event occurred. Thus, the current location of a tag that has left one reader and has not yet entered another reader, i.e., does not belong to any reader recognition area, is identified as the previous leader location in the database.

The TR-tree used in the present invention is a height balance tree based on the R-tree, and is formed by extending the R-tree to store tag trajectories. A big feature of the TR-tree is that the stored data has been extended in three dimensions and the TL can be used to directly access the terminal node.
Meanwhile, the present invention uses a tag link index, which is a secondary index, to improve the update performance of the TR-tree (TL) according to frequent movement of tag data. TL is an index using a hash having a leaf node pointer that is connected to the tag ID and entries of the terminal node of the TR-tree. By directly accessing the leaf node using the TL, operations caused by tag location and time updates can be minimized.

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When building the index for the first time, tags that visit the reader are inserted by finding the node from the root of the TR-tree, and the entry is stored in the TL. At this time, the pointer (ptr) of the TL points to the entry of the terminal node with the corresponding tag in the TR-tree index.

이 리더 4를 시간 t4에서 빠져나간다면 먼저, TL에서 태그를 찾아 단말노드의 시간 속성을 [

,

,

]로 변경하고 쓰기(write)한다. 이러한 과정을 R-tree에서 진행한다면 적어도 4번의 노드 접근비용이 발생하지만 여기서는 두 번의 노드접근이면 충분하다. 위치는 리더의 위치정보를 저장한다.The time update by tag movement proceeds as follows. For example, tag

If you exit reader 4 at time t4, first find the tag in TL and set the time attribute of the terminal node.

,

,

Change to] and write. If you do this in the R-tree, you will incur at least four node access costs, but two node accesses are sufficient here. The location stores the location information of the reader.

Advantages of TL include first, low dynamic update cost due to tag movement. That is, when updating the time and location information that is changed when the tag leaves the reader, the node can be accessed much less times than from the root to the terminal node. Second, if you find a tag in the index, you can find it in one node access.

1 is a block diagram of a locus tracking system of an RFID tag according to an embodiment of the present invention.

2 is a diagram according to an embodiment of the present invention, which shows an example of movement of an arbitrary RFID tag.

3 is a block diagram of an RFID reader among the components shown in FIG. 1.

FIG. 4 is a block diagram illustrating an apparatus for tracking a track of an RFID tag among the components shown in FIG. 1.

FIG. 5 is a diagram illustrating an example of data exchange between an RFID tag, an RFID reader, and an RFID locus tracking device, which are performed in the locus tracking system of the RFID tag shown in FIG. 1.

Claims (6)

In the locus tracking system of an RFID tag, At least one RFID reader recognizing identification information of the RFID tag entering into its area or the RFID tag leaving from its area and the entrance time or departure time; And Receive identification information of the RFID tag and the entry time or departure time of the RFID tag from the RFID reader, and update the position information of the RFID tag with the identification information of the RFID reader and the entry time or departure time of the RFID tag. An RFID tag trajectory tracking device for forming a position trajectory, and connecting the position trajectory of the RFID tag with a position trajectory in an RFID reader in which the RFID tag previously existed, The RFID tag trace tracking device, Point representing the departure time (t _l) to the RFID tag and leaves the position r _i of the second RFID reader to the RFID tag are dropping, the area of the r _i th RFID reader and, It represents the r _i r _{i + 1} and the second RFID reader position, the r _{i + 1} enters to the RFID tag enters the region of the second RFID reader time (t _e) at which the RFID tag enters a following second RFID reader Connecting the dots sequentially to form the position trajectory of the RFID tag, Where r is the RFID reader, t _l is the time when the RFID tag leaves the area of the RFID reader, t _e is the time when the RFID tag enters the area of the RFID reader r, and r _i is any time that the tag enters. The i th reader (r), r _{i + 1} of the RFID tag characterized in that the tag is any i + 1 th reader to leave the i th reader (r _i ) and enter the next reader (r _{i + 1} ) Trajectory tracking system. The method of claim 1, The RFID tag trajectory tracking device includes a database that stores trajectory information on an RFID tag, Search whether there is information of the RFID reader that existed before the RFID tag enters the RFID reader, and use the search result to determine the position trajectory of the RFID tag in the position where the RFID tag previously existed. And a track tracking system for an RFID tag. delete In the tracking method of the RFID tag, Recognizing, by any RFID reader, an RFID tag entering into its area or an RFID tag leaving from its area and recognizing the entry time or departure time of the RFID tag; Transmitting, by the reader, identification information of the entered RFID tag and an entry time or departure time of the RFID tag to an RFID tag trajectory tracking device; And The RFID tag tracking apparatus receives the identification information of the RFID tag and the entry time or departure time of the RFID tag from the reader, and uses the position information of the RFID reader and the entry time or departure time of the RFID tag. Forming a position trajectory of the RFID tag in which the tag is connected to a position trajectory of an RFID reader that previously existed, Forming the position trajectory of the RFID tag, That the RFID tag represents a departure time (t _l) and the location of the r _i th RFID reader to leave the area of the second reader and r _i, The r _i th reader Next, r _{i + 1-th} entry entering the area of the reader time (t _e) and the r _{i + 1} by connecting all the points indicating the position of the second reader the RFID tag in which the RFID tag enters Form the position trajectory of, Where r is the RFID reader, t _l is the time when the RFID tag leaves the area of the RFID reader, t _e is the time when the RFID tag enters the area of the corresponding RFID reader ( r ), and r _i is any time that the tag enters. The i th reader ( r ), r _{i + 1} of the RFID tag, characterized in that the tag is any i + 1 th reader to leave the i th reader ( r _i ) and enter the next reader ( r _{i + 1} ) Trajectory tracking method. delete The method of claim 4, wherein the position trajectory forming step of the RFID tag comprises: The RFID tag trace tracking device receiving the identifier of the RFID tag and the entry time or the departure time of the RFID tag, forms a position trace of the RFID tag in the RFID reader using the received entry time or the departure time. step; Searching, by the RFID tag trajectory tracking device, whether information of an RFID reader that existed before the RFID tag enters the RFID reader is present from its database storing trajectory information about the RFID tag; And And linking the position trajectory of the RFID tag with the position trajectory of the RFID reader that existed before the RFID reader using the search result.

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