WO2010134705A2

WO2010134705A2 - System and method for tracking the location of a container using a chirp spread spectrum

Info

Publication number: WO2010134705A2
Application number: PCT/KR2010/002682
Authority: WO
Inventors: 김상우; 조현우; 이영훈
Original assignee: 동명대학교 산학협력단
Priority date: 2009-05-19
Filing date: 2010-04-28
Publication date: 2010-11-25
Also published as: WO2010134705A3; KR100929392B1

Abstract

The invention relates to a system for tracking the location of a container using a CSS. The system for tracking a location of a container using a CSS comprises: at least four fixed nodes installed at respective predetermined reference coordinate points; at least one mobile node attached to the container to transmit/receive signals to/from the fixed nodes; and a central controller which controls the fixed node to measure the distance between the fixed node and the mobile node through said transmitted/received signals, and to measure the location of the mobile node on the basis of the measured distance.

Description

Location Tracking System and Method of Port Container Using Spread Signal Spread Spectrum

The present invention relates to a system and method for tracking the location of containers located in a port, and more particularly, to a system and method for tracking the location of a port container from distance measurement data based on chirp spread spectrum (CSS).

Location tracking technology is used in a variety of applications such as speeding vehicles, anti-lost, and various location-based services. Ultrasound is used as a means that can be used in such a positioning technique. The position tracking technology using ultrasonic waves calculates the time when the ultrasonic waves are generated by the ultrasonic generator to be reflected by the reflector and reaches the ultrasonic generator and the speed of the ultrasonic waves to calculate the distance between the ultrasonic generator and the ultrasonic reflector. can do.

The location tracking technology using the ultrasonic wave has many problems such as the straightness problem and the short distance of the ultrasonic wave in that the ultrasonic wave is used as the medium.

As an alternative to the location tracking technology using ultrasound, a location tracking technology using impulse-radio ultra wide band (IR-UWB) and chirp spread spectrum (CSS) has been proposed.

IR-UWB and CSS are communication methods defined in the standard IEEE 802.15.4a derived from the IEEE 802.15.4 standard suitable for wireless sensor networks. Both of these methods provide a function of measuring the distance between two communication nodes that have communicated based on the arrival time of a radio signal.

IR-UWB and CSS are based on wireless signal and use omni-directional antenna to solve the problem of linearity of signal of ultrasonic signal, which is mainly used for conventional location tracking, and to locate long distance up to 100m. . IR-UWB and CSS also have the advantage of being robust to multipath environments.

Due to these advantages, various researches on position measurement and its application using IR-UWB and CSS have been conducted. However, IR-UWB has a high development cost at this time, and there is a problem that the frequency band used is not internationally licensed.

The present invention is designed to solve the above problems, and one object of the present invention is easier to develop than IR-UWB and uses a frequency near 2.4 GHz. It provides a system and method that can be applied to location tracking of port containers by using it as an active tag.

An aspect of the present invention provides a location tracking system for a port container using CSS, comprising: at least four fixed nodes installed at a predetermined reference coordinate point; At least one mobile node attached to each container and transmitting and receiving signals to and from the fixed node; And a central controller configured to control the fixed node to measure the distance between the mobile nodes from the fixed node through the transmission / reception signal, and to measure the position of the mobile node based on the measured distance.

The fixed node and the mobile node transmit and receive signals in a CSS (Chirp Spread Spectrum) method, the central control unit measures the distance between the fixed node and the mobile node in the CSS method, the mobile node to the attached container And a positioning flag for indicating a status of whether or not positioning has been completed, wherein the status indication of the positioning flag includes at least a loading completion status indicating completion of loading and an undetermined status indicating not yet loaded. It may include.

The location tracking system of the port container using the CSS may further include noise and error processing means for processing the noise and error of the measured distance.

According to another aspect of the present invention, there is provided a location tracking method of a port container using CSS, the method comprising: transmitting an information acquisition command of a container from a central controller to a fixed node; Broadcasting a container information request signal from a fixed node in response to the information obtaining command; In response to the container information request signal, determining whether each of the at least one mobile node has its own positioning flag included in it being loaded or undetermined; Transmitting, to the fixed node, its information stored therein from a mobile node having the location flag in an undetermined state; Transmitting the information from the fixed node to a central control device; And measuring a distance between the fixed node and the mobile node based on the information.

Another aspect of the present invention provides a method for positioning a harbor container using CSS, the method comprising: sequentially transmitting a distance measurement command from the central control unit to at least four fixed nodes; The fixed node transmitting and receiving a signal with at least one mobile node in response to the distance measurement command; Transmitting the information received from the mobile node to the central control device; Performing, by the central control apparatus, a distance measurement between the height and the mobile node based on information received from the mobile node; Calculating, by the central control unit, the position of the mobile node by using the measured measurement distance and coordinate values of the fixed node after the distance measurement to the fixed node and the mobile node is completed; And verifying, by the central control apparatus, the position of the container based on the position tracking result.

The method further includes processing noise and errors involved in performing the distance measurement, wherein processing the noise and errors comprises a nonlinear state equation that includes equations for triangulation and coordinate changes over time of the mobile node. And by applying it to the Extended Kalman filter to estimate the coordinates of the mobile node, the nonlinear state equation is

[Equation 1]

[Equation 2]

Where x (i), y (i), and z (i) are the three-dimensional coordinates of the mobile node at sample time, δx (i), δy (i), and δz (i), respectively, The coordinate fluctuation values, w1 (i), w2 (i), and w3 (i) of the mobile node 106 changed by the movement of the crane 109 during the time interval are measured noises measured at each coordinate fluctuation value, y1. (i), y2 (i), y3 (i), and y4 (i) are the distances measured between the mobile node 106 and each of the

fixed nodes

101, 102, 103, and 104, v1 (i), v2 (i), v3 (i), and v4 (i) are noises included in the measured distance, and axk, ayk, and azk are three-dimensional coordinates of the k-th fixed node, and Equation 1 is a moving state of the mobile node. Equation 2 can be expressed as a trigonometric equation.

Processing the noise and error,

,

And

Is a coordinate value estimated by the Kalman filter, a vector consisting of a distance value calculated by the estimated coordinates.

To,

Define as

A vector of measured distances,

The ratio of the magnitudes of the two vectors,

The distance value vector measured by multiplying the ratio r.

To,

And convert the measured distance vector

Not

May be applied to the Extended Kalman filter.

The method includes the step of transmitting, by the central control unit, a command to the fixed node to notify that the location tracking of the container is completed after confirming that the container has moved to the verified location; Transmitting, by the fixed node, a signal indicating completion of location tracking to the mobile node attached to the container; And in response to the signal for notifying completion of the location tracking, changing the location determination flag included therein from the undetermined state to the completed load state and ending the communication.

According to the position tracking system and method of a port container using CSS according to the present invention, it is possible to know the absolute coordinate value of the container to be moved through a crane, and thus the container is located at a position different from the intended position by a driver's mistake. Positioning can be prevented and the desired container position can be easily found.

1 is a system diagram schematically showing a location tracking system of a port container using a CSS according to an embodiment of the present invention,

2 is a flowchart illustrating an exemplary distance measurement process for a location tracking method of a port container using CSS according to an embodiment of the present invention;

3 is a flowchart illustrating a location tracking method of a port container using CSS according to an embodiment of the present invention; and

4 is another exemplary flowchart illustrating a location tracking method of a port container using CSS according to an embodiment of the present invention.

Hereinafter, the same reference numerals will be described in detail with reference to the accompanying drawings, with reference to the same components preferred embodiments of the present invention. The terms or words used in the specification and claims are not to be construed as being limited to conventional or dictionary meanings, but should be construed as meanings and concepts corresponding to the technical matters of the present invention.

The embodiments described in the specification and the configuration shown in the drawings are preferred embodiments of the present invention, and do not represent all of the technical idea of the present invention, various equivalents and modifications that can be substituted for them at the time of the present application are There may be.

1 is a system diagram schematically showing a location tracking system of a port container using a CSS according to an embodiment of the present invention.

Referring to FIG. 1, a port container position tracking system 1 according to an embodiment of the present invention includes fixed

nodes

101, 102, 103, and 104, and

containers

105a and 105b installed at predetermined reference coordinate points.

Mobile nodes

106a and 106b attached thereto, and a central control unit 107 installed in the container cab to control the fixed

nodes

101, 102, 103, and 104 and the

mobile nodes

106a and 106b, respectively. Include.

The central control unit 107 serves to control the positioning system 1 by issuing commands to the respective

fixed nodes

101, 102, 103, and 104. Specifically, the central control unit 107 includes (not shown) transmission and reception means and transmits signals to the fixed

nodes

101, 102, 103, and 104 through the fixed

nodes

101, 102, 103, and 104. And receive signals from fixed

nodes

101, 102, 103, and 104.

The central control unit 107 is a fixed

node

101, 102, 103, and 104 from the

mobile node

106a and 106b as a result of the signal transmission and reception between the fixed

nodes

101, 102, 103, and 104 and the

mobile nodes

106a and 106b. Information can be received via) and the distance between the fixed

nodes

101, 102, 103, and 104 and the

mobile nodes

106a and 106b can be measured based on the information.

The fixed

nodes

101, 102, 103, and 104 may include (not shown) transmission and reception means and may receive command signals from the central control unit 107 and transmit necessary information to the central control unit 107. .

The

mobile nodes

106a and 106b include (not shown) transceiving means and may communicate with fixed

nodes

101, 102, 103, and 104 via them.

The fixed

nodes

101, 102, 103, and 104 and the

mobile nodes

106a and 106b are implemented as CSS-based nodes to wirelessly move from the

mobile nodes

106a and 106b to the fixed

nodes

101, 102, 103, and 104. Based on the arrival time of the signal, it is possible to measure the distance between two communication nodes in which communication has been performed and thus position tracking.

Each

mobile node

106a and 106b of

containers

105a and 105b contains information about the

containers

105a and 105b to which it is attached and indicates whether the positioning of

containers

105a and 105b has been completed (not shown). ) Further includes a positioning flag.

Such a positioning flag may indicate whether the container is positioned by maintaining a loading completion state in the case of a container already loaded on the yard, and in an undetermined state if the position is not yet determined.

The location tracking system of a port container using CSS according to an embodiment of the present invention may further include (not shown) noise and error processing means for processing noise and error of the measured distance.

A detailed implementation method of the noise and error processing means will be described later in detail.

2 is a flowchart illustrating an exemplary distance measurement process for a location tracking method of a port container using CSS according to an embodiment of the present invention.

First, when a new container 105a is carried by the yard tractor 108, the crane 109 starts an operation for lifting the container 105a. At this time, the central control unit 107 instructs a fixed node 101 to obtain information of a new container (step S10).

The fixed node 101 which received the command of the central control apparatus 107 transmits the container information request signal which requests container information by a broadcasting method (step S30). This container information request signal is transmitted in a broadcast manner so that not only the mobile node 106a attached to the new container 105a that is currently transported, but also the mobile node 106b of the container 105b that is already positioned can be received. Can be.

At this time, only the mobile node 106a having its positioning flag in an undetermined state transmits its information to the fixed node 101 in response to the received container information request signal (step S70).

That is, each of the

mobile nodes

106a and 106b determines whether its positioning flag included therein is a loaded state or an undetermined state (step S50), and determines that the container 105b that is already in the loaded state has been determined. The mobile node 106b does not respond to the container information request signal, and only the mobile node 106b of the currently transported container 105a with the positioning flag undetermined will transmit its information to the fixed node 101. (Step S70).

The fixed node 101 which has received the information from the mobile node 106b transmits the information back to the central control unit 107 (step S90), and from this point on, the central control unit 107 is based on the received information. Instructs the fixed node 101 of to perform the distance measurement between the fixed node 101 and the moving node 106a of the container 105a currently carried (step S110). Each of the fixed

nodes

101, 102, 103, 104 measures the distance between the fixed

nodes

101, 102, 103, 104 and the mobile node 106a in response to a command from the central control unit 107. (Step S130).

The distance measurement may be performed by the fixed

nodes

101, 102, 103, and 104 sequentially, and the position of the mobile node 106a may be measured by triangulation according to the measured distance.

In this way, only the mobile node which is in an undetermined state is configured to transmit the information contained in the fixed node to the fixed node according to whether the positioning flag is in the loaded state or the undetermined state. The collision of signals between the mobile node 106b and the fixed

nodes

101, 102, 103, 104 can be prevented.

3 is a flowchart illustrating a location tracking method of a port container using CSS according to an embodiment of the present invention.

The location tracking of the transported container is by triangulation based on ranging data between the fixed

nodes

101, 102, 103, and 104 and the mobile node 106 attached to the container 105 measured in the manner described above. Can be done.

To this end, the central control unit 107 sequentially transmits the distance measurement command to each of the fixed

nodes

101, 102, 103, and 104 (step S20). The fixed

nodes

101, 102, 103, and 104 transmit and receive signals to and from the mobile node 106 in response to the distance measurement command (step S40) and based on the information received from the

mobile node

106, 101, 102, 103, and 104 and the distance measurement between the mobile node 106 is performed (step S60).

Once the distance measurements to all fixed

nodes

101, 102, 103, and 104 and the mobile node 106 have been completed, the fixed

nodes

101, 102, 103, and 104 are measured by the central control unit 107. In step S80, the central control apparatus 107 may receive a location of the mobile node 106 using the received four measurement distances and coordinate values of a fixed node known in advance (step S100). .

The location tracking method of a port container using CSS according to an embodiment of the present invention may be influenced by noise and include an error in distance measurement.

The method may further include a step (S120) of processing noise and an error that may be included in a location tracking method of a port container using CSS according to an embodiment of the present invention.

First, the noise processing of the measurement distance can be performed by using a triangulation equation and a nonlinear state equation describing the change of coordinates over time of the mobile node and applying the extended Kalman filter to estimate the coordinates of the mobile node. .

The nonlinear state equations are as shown in Equations 1 and 2 below.

[Equation 1]

[Equation 2]

Where x (i), y (i), and z (i) are the three-dimensional coordinates of the mobile node at sample time, respectively, and δx (i), δy (i), and δz (i) during the sample time interval. The coordinate variation value of the mobile node 106 changed by the movement of the crane 109 is shown. w1 (i), w2 (i), and w3 (i) represent the measurement noise measured at each coordinate change value. y1 (i), y2 (i), y3 (i), and y4 (i) are the distances measured between the mobile node 106 and each of the fixed

nodes

101, 102, 103, and 104, and v1 (i ), v2 (i), v3 (i), and v4 (i) represent the noise included in the measured distance. And axk, ayk, and azk represent three-dimensional coordinates of the k-th fixed node.

Equation 1 is a model for a moving state of a mobile node, and Equation 2 expresses triangulation as an equation. Since the state equation includes noise, the three-dimensional coordinate value of the mobile node can be estimated by applying this nonlinear state equation to the Extended Kalman filter.

The Extended Kalman filter can produce normal results for cases where the noise average is zero. However, typical measurements include an error, which means that the average of the measurements is not zero, so additional methods are needed to correct this error. Therefore, in the present invention, the error is corrected through the following method before applying the measured data to the Extended Kalman filter.

,

And

Is a coordinate value estimated by the Kalman filter, a vector of distance values calculated by the estimated coordinates.

Is defined as in Equation 3 below.

[Equation 3]

You can also take a vector of measured distances

Defined as

[Equation 4]

The ratio of the magnitudes of the two vectors is represented by r.

[Equation 5]

Distance vector measured by multiplying this ratio r

As follows

Convert to

[Equation 6]

That is, in the present invention, the measured distance vector

Not

Apply to Extended Kalman filter.

The position of the container is verified based on the result of the position tracking (step S140).

If it is confirmed that the container has moved to the verified position, the central control unit 107 transmits a command to the fixed node 101 indicating that the location tracking of the container is completed (step S160), the fixed node 101 is The mobile station 106 attached to the container transmits a signal indicating completion of location tracking (step S180). Upon receipt of this signal, the mobile node 106 changes the positioning flag to the loading complete state and ends communication (step S200).

Referring to Figure 4 relates to the process of moving the container loaded in the yard back to the yard tractor 108, this process is also similar to each step of the location tracking method of the port container using the CSS according to an embodiment of the present invention described above Do.

First, the central control unit 107 transmits information about the container to be moved to the fixed node 101 (step S200). The fixed node 101 broadcasts the corresponding container information received (step S220) and all mobile nodes which have received it check whether the information matches their own information (step S240). Here, only one container corresponds to the corresponding information, and the mobile node of the container transmits a response signal for the received container information to the fixed node 101 (step S260).

The fixed node 101 transmits this information to the central control unit 107 again (step S280), and the central control unit 107 starts tracking the position of the container from this moment (step S300). According to the position tracking result, the crane can move to the position of the container and transport it.

The technical spirit of the present invention has been described above with reference to the accompanying drawings, but this is only illustrative of the preferred embodiments of the present invention and is not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims

Port container positioning system using CSS,

At least four fixed nodes installed at predetermined reference coordinate points;

At least one mobile node attached to each container and transmitting and receiving signals to and from the fixed node; And

And a central controller configured to control the fixed node to measure a distance between the mobile nodes from the fixed node through the transmission and reception signal, and to measure the position of the mobile node based on the measured distance.

The fixed node and the mobile node transmits and receives signals in a CSS (Chirp Spread Spectrum) method, the central control unit measures the distance between the fixed node and the mobile node in the CSS method,

The mobile node includes a positioning flag that includes information about the attached container and indicates a status of whether or not location tracking has been completed, wherein the status indication of the positioning flag includes at least a loading completion status indicating completion of loading and yet. Positioning system of a port container, characterized in that it comprises an undetermined state indicating that the state is not loaded.
The position tracking system of claim 1, further comprising noise and error processing means for processing the noise and error of the measured distance.
Positioning method of port container using CSS,

Transmitting the information acquisition command of the container from the central control device to one fixed node;

Broadcasting a container information request signal from a fixed node in response to the information obtaining command;

In response to the container information request signal, determining whether each of the at least one mobile node has its own positioning flag included in it being loaded or undetermined;

Transmitting, to the fixed node, its information stored therein from a mobile node having the location flag in an undetermined state;

Transmitting the information from the fixed node to a central control device; And

And measuring a distance between the fixed node and the mobile node based on the information.
Positioning method of port container using CSS,

Sequentially transmitting a ranging command from the central control device to at least four fixed nodes;

The fixed node transmitting and receiving a signal with at least one mobile node in response to the distance measurement command;

Transmitting the information received from the mobile node to the central control device;

Performing, by the central control apparatus, a distance measurement between the height and the mobile node based on information received from the mobile node;

Calculating, by the central control unit, the position of the mobile node by using the measured measurement distance and coordinate values of the fixed node after the distance measurement to the fixed node and the mobile node is completed; And

And the central control apparatus verifying the position of the container based on the position tracking result.
5. The method of claim 4, further comprising processing noise and errors involved in performing the distance measurement, wherein processing the noise and errors comprises formulas for triangulation and coordinate changes over time of the mobile node. This is done by describing a nonlinear state equation and applying it to an Extended Kalman filter to estimate the coordinates of the mobile node.

[Equation 1]

[Equation 2]

Where x (i), y (i), and z (i) are the three-dimensional coordinates of the mobile node at sample time, δx (i), δy (i), and δz (i), respectively, The coordinate fluctuation values, w1 (i), w2 (i), and w3 (i) of the mobile node 106 changed by the movement of the crane 109 during the time interval are measured noises measured at each coordinate fluctuation value, y1. (i), y2 (i), y3 (i), and y4 (i) are the distances measured between the mobile node 106 and each of the fixed nodes 101, 102, 103, and 104, v1 (i), v2 (i), v3 (i), and v4 (i) are noises included in the measured distance, and axk, ayk, and azk are three-dimensional coordinates of the k-th fixed node, and Equation 1 is a moving state of the mobile node. Equation 2 is a model for the location tracking method of a port container, characterized in that the triangulation expressed by the formula.
The method of claim 5, wherein the processing of the noise and error,

,
And
Is a coordinate value estimated by the Kalman filter, a vector consisting of a distance value calculated by the estimated coordinates.
To,

Define as

A vector of measured distances,

The ratio of the magnitudes of the two vectors,

The distance value vector measured by multiplying the ratio r.
To,

And convert the measured distance vector
Not And applying the extended Kalman filter to the port container.
7. The method of claim 6, further comprising: after confirming that the container has moved to the verified location, the central control unit sending a command to the fixed node informing that the location tracking of the container is completed;

Transmitting, by the fixed node, a signal indicating completion of location tracking to the mobile node attached to the container; And

And in response to the signal indicating that the location tracking is completed, changing the location determination flag included therein from the undetermined state to the completed loading state and terminating the communication. Way.