Asset tracking system and method

Abstract

An asset tracking system and method are provided that are adapted to track the precise location of an asset. In order to accurately track the location of an asset, the present invention measures the asset location, which is the location of an asset terminal installed on the asset to be tracked, measures the relative location of the asset terminal with respect to the reference terminal through communication between the reference terminal and the asset terminal, and corrects the asset location using the relative location, thereby minimizing measurement errors of the asset location compared to a method of measuring the asset location using only GPS communication.

Description

[Technical field]

[0001] The present invention relates to technology for tracking the location of assets such as cargo, containers, and pallets. [Background technology]

[0002] Containers are used to transport cargo efficiently and economically. After loading palletized cargo into a container, the container is transported by a vehicle, ship, airplane, or other means of transportation.

[0003] Containers are often left at ports or warehouses for long periods of time before being loaded onto vehicles, or are left and used for long periods of time inside vehicles, which means that there are frequent incidents of theft of cargo loaded into containers and illegal addition of cargo.

[0004] Therefore, in order to ensure the safe transportation and management of cargo, asset tracking technology is being applied, in which various sensors are attached to transportation structures such as containers and pallets, and the sensing information and location information detected by these sensors are transmitted to a management server.

[0005] In conventional asset tracking technology, a GPS system is usually used to track the location of an asset, but there is a problem that it is difficult to track the exact location of an asset due to the position deviation of the GPS. Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made to solve the above problems, and aims to provide an asset tracking system and method that uses the relative positions of a reference terminal and a positioning target to correct the asset position determined by GPS information, thereby tracking the exact position of the asset. [Means for solving the problem]

[0007] In order to achieve the above object, an asset tracking system according to one embodiment of the present invention includes a reference terminal, a plurality of asset terminals that are installed on assets to be tracked and perform UWB communication with the reference terminal to measure relative positions based on the reference terminal, and a management server that collects asset positions and relative positions from the plurality of asset terminals and corrects the asset positions of the asset terminals using the relative positions.

[0008] In order to achieve the above-mentioned objective, an asset tracking method according to one aspect of the present invention includes a step of collecting asset positions generated based on GPS signals from a plurality of asset terminals, a step of collecting from the plurality of asset terminals relative positions based on the reference terminal generated by UWB communication between the reference terminal and the asset terminal, a step of generating a reference position corresponding to the position of the reference terminal based on the asset positions collected in the step of collecting asset positions, and a step of generating a corrected asset position by reflecting the relative position based on the reference position generated in the step of generating the reference position.

[0009] In order to achieve the above-mentioned object, an asset tracking method according to another aspect of the present invention includes the steps of forming one or more groups by a plurality of asset terminals through mutual communication; setting a master asset terminal and a plurality of slave asset terminals of the group by the asset terminals belonging to each group in the group forming step; collecting, by a management server, one of the asset positions of the plurality of slave asset terminals generated based on GPS signals and the asset position of the master asset terminal from the master asset terminal of each group; collecting, by the management server, relative positions of the plurality of slave asset terminals based on the master asset terminal from the master asset terminal of each group; setting, by the management server, a reference position based on the asset position of the master asset terminal collected in the asset position collecting step; and generating, by the management server, corrected asset positions of the plurality of slave asset terminals by reflecting the relative positions based on the reference position generated in the reference position generating step. Effect of the Invention

[0010] According to the present invention, the asset tracking system and method reflects the relative position measured by UWB communication and corrects the asset position measured based on GPS communication, thereby minimizing measurement errors of the asset position compared to conventional techniques that measured the asset position using only GPS communication.

[0011] In addition, the asset tracking system and method reflects the relative position measured by UWB communication and corrects the asset position measured based on GPS communication, which results in some error with the actual position of the asset, but the relative position based on the reference terminal can be displayed as the same as the actual position, thereby improving the accuracy of asset tracking.

[0012] In addition, the asset tracking system and method classifies a plurality of asset terminals into groups, sets at least one master asset terminal for each group, and corrects the asset position measured by GPS information using the relative positions of the master asset terminal and the slave asset terminal, thereby minimizing measurement errors of the asset position compared to the conventional technology that measures the asset position using only GPS communication. In this case, although there is some error with the actual position of the asset, the asset tracking system and method can display the relative position based on the reference terminal as the same as the actual position, thereby improving the accuracy of asset tracking.

[0013] In addition, the asset tracking system and method classifies multiple asset terminals into groups, and sets the asset position using the relative positions of the slave asset terminals with the position of the master asset terminal of each group as a reference position, thereby enabling the relative positions between assets to be accurately tracked.

[0014] In addition, the asset tracking system and method improves the efficiency of the battery installed in the asset terminal by activating the GPS communication module of the master asset terminal and stopping the operation of the GPS communication module of the slave asset terminal, thereby having the effect of extending the period during which the location of assets loaded for long periods of time can be tracked. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram for explaining a conventional asset tracking system. [Diagram 2] FIG. 1 is a diagram for explaining an asset tracking system according to a first embodiment of the present invention. [Diagram 3] 3 is a diagram for explaining the configuration of the asset terminal in FIG. 2; [Figure 4] 3 is a diagram for explaining the configuration of a management server in FIG. 2; [Diagram 5] 5 is a diagram for explaining a position information storage module of FIG. 4. [Figure 6] 4 is a diagram for explaining an example in which the management server of FIG. 2 tracks (corrects) the position of the asset terminal; FIG. [Figure 7] 4 is a diagram for explaining an example in which the management server of FIG. 2 tracks (corrects) the position of the asset terminal; FIG. [Figure 8] 4 is a diagram for explaining an example in which the management server of FIG. 2 tracks (corrects) the position of the asset terminal; FIG. [Figure 9] 4 is a diagram for explaining an example in which the management server of FIG. 2 tracks (corrects) the position of the asset terminal; FIG. [Figure 10] 4 is a diagram for explaining an example in which the management server of FIG. 2 tracks (corrects) the position of the asset terminal; FIG. [Figure 11] 4 is a diagram for explaining an example in which the management server of FIG. 2 tracks (corrects) the position of the asset terminal; FIG. [Figure 12] 1 is a flowchart illustrating an asset tracking method according to a first embodiment of the present invention. [Figure 13] 13 is a flowchart for explaining a reference position setting step in FIG. 12. [Figure 14] FIG. 11 is a diagram for explaining an asset tracking system according to a second embodiment of the present invention. [Figure 15] FIG. 15 is a diagram for explaining the master asset terminal of FIG. 14. [Figure 16] FIG. 15 is a diagram for explaining the slave asset terminal of FIG. 14. [Figure 17]FIG. 15 is a diagram for explaining the configuration of the management server of FIG. [Figure 18] FIG. 18 is a diagram for explaining the position information storage module of FIG. 17. [Figure 19] FIG. 15 is a diagram for explaining an example in which the management server of FIG. 14 tracks (corrects) the position of the asset terminal. [Figure 20] FIG. 15 is a diagram for explaining an example in which the management server of FIG. 14 tracks (corrects) the position of the asset terminal. [Figure 21] FIG. 15 is a diagram for explaining an example in which the management server of FIG. 14 tracks (corrects) the position of the asset terminal. [Figure 22] FIG. 15 is a diagram for explaining an example in which the management server of FIG. 14 tracks (corrects) the position of the asset terminal. [Figure 23] FIG. 15 is a diagram for explaining an example in which the management server of FIG. 14 tracks (corrects) the position of the asset terminal. [Figure 24] FIG. 15 is a diagram for explaining an example in which the management server of FIG. 14 tracks (corrects) the position of the asset terminal. [Diagram 25] 10 is a flowchart illustrating an asset tracking method according to a second embodiment of the present invention. [Figure 26] 26 is a flowchart for explaining a reference position setting step in FIG. 25. [Figure 27] FIG. 1 is a diagram for explaining a conventional asset tracking system. [Figure 28] FIG. 11 is a diagram for explaining an asset tracking system according to a third embodiment of the present invention. [Figure 29] FIG. 29 is a diagram for explaining the master asset terminal of FIG. 28. [Diagram 30] FIG. 29 is a diagram for explaining the slave asset terminal of FIG. 28. [Diagram 31] FIG. 29 is a diagram for explaining the configuration of the management server of FIG. 28. [Diagram 32] FIG. 32 is a diagram for explaining the position information storage module of FIG. 31. [Diagram 33] FIG. 29 is a diagram for explaining an example in which the management server of FIG. 28 tracks (corrects) the position of the asset terminal. [Diagram 34] FIG. 29 is a diagram for explaining an example in which the management server of FIG. 28 tracks (corrects) the position of the asset terminal. [Diagram 35] 1 is a flow chart illustrating an asset tracking method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, in order to enable a person having ordinary skill in the art to easily implement the technical concept of the present invention, the most preferred embodiment of the present invention will be described with reference to the drawings. First, when assigning reference numerals to components in each drawing, the same components are assigned the same numerals as much as possible even if they are shown in different drawings. In addition, when describing the present invention, if it is determined that a detailed description of related known configurations or functions may obscure the gist of the present invention, the detailed description will be omitted.

[0017] Referring to Fig. 1, in the past, in order to track the locations of assets 1, 2, 3, 4, 5, and 6, a GPS-based location tracking terminal is usually attached to the asset (i.e., a container) and loaded into an open storage yard. In this case, the asset tracking system tracks the location of the asset using the location information measured by the location tracking terminal.

[0018] A tracking terminal typically uses a GPS to measure location information 1', 2', 3', 4', 5', and 6' corresponding to the current location of an asset. However, positioning using GPS can have a positioning error of several tens of meters or more, so a location different from the actual location of the asset may be measured as the asset location, and therefore the asset location cannot be tracked accurately, and the relative location of the asset is tracked differently from the actual location.

[0019] In the first embodiment of the present invention, the accurate location of the asset is tracked by correcting the asset location measured by GPS information using the relative location between the reference terminal and the target to be measured. In other words, in the first embodiment of the present invention, the asset location measured based on GPS is corrected using UWB communication to minimize the error between the actual location of the asset and the measured location, and the relative location of the asset can be understood to be the same as the actual location.

[0020] To that end, referring to FIG. 2, an asset tracking system according to an embodiment of the present invention includes a plurality of asset terminals 100, a reference terminal 200, and a management server 300. In the asset tracking system shown in FIG.

[0021] The asset terminal 100 is a communication terminal attached (or installed) to the asset 10 for asset management. The asset terminal 100 generates first location information corresponding to the current location of the asset 10 through GPS communication. The asset terminal 100 generates second location information corresponding to the relative location with the reference terminal 200 through UWB communication. Here, the asset terminal 100 generates the second location information including a direction and a distance. The asset terminal 100 transmits the first location information and the second location information to the management server 300.

[0022] 3, the asset terminal 100 includes a first communication module 110, an asset position generating module 120, a second communication module 130, a relative position generating module 140, a control module 150, and a third communication module 160. Here, the first communication module 110 is a GPS communication module that receives GPS signals from a satellite, the second communication module 130 is a UWB communication module that communicates with an adjacent reference terminal 200, and the third communication module 160 is a Sigfox communication module that communicates with the management server 300 and the asset terminal 100 through low-power communication, for example.

[0023] The first communication module 110 receives a signal in the GPS frequency band (hereinafter, referred to as a GPS signal). The first communication module 110 transmits the received GPS signal to the asset position generation module 120.

[0024] The asset position generation module 120 generates an asset position corresponding to the current position of the asset 10 based on the GPS signal transmitted from the first communication module 110 in response to an asset position generation request from the control module 150. Here, since generating location information using a GPS signal is a common technique, detailed description thereof will be omitted.

[0025] The asset location generating module 120 generates a first location information transmission request including the asset location and a unique identifier of the asset terminal 100. The asset location generating module 120 transmits the first location information transmission request to the control module 150.

[0026] The second communication module 130 transmits and receives signals in the UWB frequency band (hereinafter, UWB signals) The second communication module 130 transmits and receives UWB signals to and from the reference terminal 200, and transmits the received information to the relative position generating module 140.

[0027] The relative position generating module 140 transmits a positioning request for requesting measurement of a relative position to the second communication module 130 in response to an asset position generating request from the control module 150. The relative position generating module 140 receives a delay time from the second communication module 130, and generates a relative position of the asset terminal 100 based on the reference module based on the delay time. In this case, the relative position generating module 140 generates the relative position using positioning techniques such as Time Difference of Arrival (TDoA) and Two Way Ranging (TWR).

[0028] As an example, the second communication module 130 receives a UWB signal (i.e., an advertising signal, a position measurement request signal) from the reference terminal 200 and transmits it to the relative position generating module 140. The relative position generating module 140 transmits a request for transmitting a Ranging Request signal to the second communication module 130, and the second communication module 130 transmits a Ranging Request signal to the reference terminal 200 in response to the request for transmitting the Ranging Request signal. The reference terminal 200 that receives the Ranging Request signal transmits a first UWB pulse, and the second communication module 130 transmits a second UWB pulse in response to the first UWB pulse transmitted by the reference terminal 200. The reference terminal 200 calculates a delay time between the first UWB pulse and the second UWB pulse, and transmits it to the second communication module 130. The second communication module 130 transmits the received delay time to the relative position generating module 140, and the relative position generating module 140 uses the delay time to generate a relative position of the asset terminal 100 based on the position of the reference terminal 200.

[0029] The relative position generating module 140 generates second position information including the relative position, the unique identifier of the reference terminal 200, and the unique identifier of the asset terminal 100. The relative position generating module 140 transmits the second position information to the control module 150.

[0030] The control module 150 transmits an asset position generation request to the asset position generation module 120 and the relative position generation module 140. In this case, the control module 150 receives the asset position generation request from the management server 300 via the second communication module 130, or transmits the asset position generation request when a set time arrives.

[0031] The control module 150 receives the first location information and the second location information in response to the asset location generation request. The control module 150 receives the first location information, which is location information generated based on a GPS signal, from the asset location generation module 120. The control module 150 receives the second location information, which is relative location information generated based on a UWB signal, from the relative location generation module 140.

[0032] The control module 150 generates a location information transmission request including the first location information and the second location information. In this case, the control module 150 may generate a first location information transmission request including the first location information and a second location information transmission request including the second location information. The control module 150 transmits the location information transmission request to the third communication module 160.

[0033] The third communication module 160 transmits the first location information and the second location information to the management server 300 in response to a location information transmission request from the control module 150. The third communication module 160 converts the first location information and the second location information into a Sigfox protocol and transmits the converted information to the management server 300.

[0034] The reference terminal 200 is a communication terminal arranged in the vicinity of the asset 10 to correct the position measured by the asset terminal 100. The reference terminal 200 may be composed of a portable terminal carried by a manager, an asset terminal 100 installed on the asset 10, a terminal fixedly installed at the location where the asset terminal 100 is loaded, one of the multiple asset terminals 100, etc.

[0035] The reference terminal 200 transmits and receives UWB signals to and from the second communication module 130 of the asset terminal 100. To this end, the reference terminal 200 includes a communication module capable of communicating with the second communication module 130 of the asset terminal 100. The reference terminal 200 outputs an advertising signal or a position measurement request signal. The reference terminal 200 transmits a first UWB pulse to the asset terminal 100 in response to a ranging request signal from the asset terminal 100. The reference terminal 200 receives a second UWB pulse from the asset terminal 100 in response to the first UWB pulse. The reference terminal 200 calculates a delay time between the first UWB pulse and the second UWB pulse, and transmits the calculated delay time to the asset terminal 100.

[0036] The management server 300 collects position information from multiple asset terminals 100. The management server 300 collects asset positions based on GPS and relative positions based on UWB. The management server 300 corrects the asset positions using the relative positions, and outputs the corrected asset positions generated as the correction results.

[0037] To that end, referring to FIG. 4, the management server 300 includes a fourth communication module 310, a position information storage module 320, a reference position generating module 330, a correction module 340, and an output module 350.

[0038] The fourth communication module 310 receives first location information and second location information from a plurality of asset terminals 100. The fourth communication module 310 receives the first location information including an asset location and a unique identifier of the asset terminal 100, and the second location information including a relative location, a unique identifier of the reference terminal 200, and a unique identifier of the asset terminal 100. The fourth communication module 310 transmits a location information storage request including the first location information and the second location information to the location information storage module 320.

[0039] The location information storage module 320 stores the first location information and the second location information in response to a location information storage request from the fourth communication module 310. At this time, referring to Fig. 5, the location information storage module 320 stores the unique identifier of the asset terminal 100, the unique identifier of the reference terminal 200, the asset location, and the relative location in association with each other.

[0040] The location information storage module 320 detects the unique identifier and the reference location from the reference location storage request in response to the reference location storage request from the reference location generation module 330. The location information storage module 320 stores the reference location in association with the unique identifier of the reference terminal 200 that is the same as the detected unique identifier.

[0041] The location information storage module 320 detects the unique identifier and the corrected asset location from the asset location storage request in response to the asset location storage request from the correction module 340. The location information storage module 320 stores the corrected asset location in association with the unique identifier of the asset terminal 100 that is the same as the detected unique identifier.

[0042] The reference position generating module 330 generates a reference position of the reference terminal 200 based on the asset positions and the relative positions stored in the position information storing module 320 .

[0043] The reference position generating module 330 detects information associated with the unique identifier of the same reference terminal 200 from the position information storage module 320. The reference position generating module 330 detects the unique identifier, asset position, and relative position of the asset terminal 100 associated with the unique identifier of the same reference terminal 200.

[0044] The reference position generating module 330 extracts the midpoint of two asset terminals 100 located at facing points with respect to the reference terminal 200. In this case, the reference position generating module 330 detects a position of each asset terminal 100 moved from the asset position in the direction of the relative position by the distance of the relative position. The reference position generating module 330 extracts, as the midpoint, a half point of a straight line connecting the positions of the two asset terminals 100 located at facing points from among the detected positions.

[0045] On the other hand, the reference position generating module 330 may generate a reference position of the reference terminal 200 based on the asset position stored in the position information storing module 320 .

[0046] The reference position generation module 330 detects information associated with the unique identifier of the same reference terminal 200 from the position information storage module 320. The reference position generation module 330 detects the unique identifier and asset position of the asset terminal 100 associated with the unique identifier of the same reference terminal 200.

[0047] The reference position generating module 330 extracts the midpoint of two asset terminals 100 located at opposite points with respect to the reference terminal 200. In this case, the reference position generating module 330 extracts a half point of a straight line connecting the asset positions of the two asset terminals 100 located at opposite points with the reference terminal 200 as the midpoint.

[0048] When the extraction of the intermediate points is completed, the reference position generating module 330 extracts the center point of the figure connecting the intermediate points and generates it as a reference position (i.e., the position of the reference terminal 200). The reference position generating module 330 generates a reference position storage request including the unique identifier and reference position of the reference terminal 200 and transmits it to the position information storage module 320. The reference position generating module 330 transmits a position correction request including the unique identifier and reference position of the reference terminal 200 to the correction module 340.

[0049] The correction module 340 generates a corrected asset position in response to the position correction request from the reference position generation module 330. That is, the correction module 340 detects the unique identifier and reference position of the reference terminal 200 from the position correction request. The correction module 340 detects the unique identifier and relative position of the asset terminal 100 linked to the unique identifier of the reference terminal 200 from the position information storage module 320. The correction module 340 uses the reference position as a reference point, positions the asset terminal 100 reflecting the relative position, and generates a corrected asset position of each asset terminal 100. The correction module 340 generates an asset position storage request including the unique identifier and the corrected asset position of the asset terminal 100 and transmits it to the position information storage module 320. The correction module 340 generates an asset output request and transmits it to the output module 350.

[0050] The output module 350 outputs the reference terminal 200 and the multiple asset terminals 100 on a screen in response to an output request from the correction module 340. In this case, the output module 350 outputs a screen in which the reference terminal 200 is displayed at the reference position and the asset terminal 100 is displayed at the corrected asset position.

[0051] An example in which the management server 300 corrects the position of the asset terminal 100 will be described below with reference to FIGS.

[0052] First, as shown in Fig. 6, a state in which the first asset terminal A1 to the sixth asset terminal A6 are piled up in an open storage yard will be described as an example. The first asset terminal A1 and the sixth asset terminal A6 are located at opposite points with respect to the reference terminal R, the second asset terminal A2 and the fifth asset terminal A5 are located at opposite points with respect to the reference terminal R, and the third asset terminal A3 and the fourth asset terminal A4 are located at opposite points with respect to the reference terminal R.

[0053] Referring to Figure 7, the asset positions A1' to A6' collected from the asset terminal 100 are generated based on GPS signals, and therefore are displayed differently from the actual positions, and the relative positions between the asset terminals 100 are also displayed differently from the actual positions.

[0054] To correct this, the management server 300 sets a reference position corresponding to the position of the reference terminal 200 .

[0055] 8, the management server 300 detects, for each asset terminal 100, a position moved from the asset position in the direction of the relative position by the distance of the relative position as the asset position.

[0056] The management server 300 extracts as a midpoint a half point of a straight line connecting the asset positions of two asset terminals 100 located at opposite points with respect to the reference terminal 200. In this case, A, which is the center point between the first asset terminal A1 and the sixth asset terminal A6, B, which is the center point between the second asset terminal A2 and the fifth asset terminal A5, and C, which is the center point between the third asset terminal A3 and the fourth asset terminal A4, are extracted.

[0057] The management server 300 extracts the center point D of the triangle formed by connecting the extracted intermediate points A, B, and C, and generates this as the reference position (R'', ie, the position of the reference terminal 200).

[0058] Meanwhile, referring to FIG. 9, the management server 300 may extract the half points of a straight line connecting the asset positions (asset positions not reflecting the relative positions) of two asset terminals 100 located at opposite points with respect to the reference terminal 200 as midpoints A, B, and C.

[0059] Referring to Figure 10, the management server 300 sets the reference position R'' as the position of the reference terminal 200, arranges each asset terminal 100 to reflect the relative position of the asset terminal 100 based on the reference position R'', and generates corrected asset positions A1'' to A6'' for each asset terminal 100.

[0060] As a result, as shown in FIG. 11, the corrected asset positions A1''-A6'' generated by the management server 300 can reduce errors compared to the asset positions A1'-A6' measured based on the GPS signal, and although there is an error from the actual positions A1-A6, the relative positions based on the reference terminal 200 can be displayed in the same way, thereby improving the accuracy of asset tracking.

[0061] Hereinafter, an asset tracking method according to an embodiment of the present invention will be described with reference to the drawings.

[0062] 12, the management server 300 collects asset locations from a plurality of asset terminals 100 (S110). The plurality of asset terminals 100 measure their asset locations based on GPS signals and transmit the asset locations to the management server 300 upon request from the management server 300. The management server 300 stores the asset locations transmitted from the plurality of asset terminals 100. In this case, the management server 300 stores the unique identifiers of the asset terminals 100 in association with the asset locations.

[0063] The management server 300 collects relative positions from a plurality of asset terminals 100 (S120). The plurality of asset terminals 100 measure their relative positions based on the reference terminal 200 through UWB communication with the reference terminal 200, and transmit the relative positions to the management server 300 upon request from the management server 300. The management server 300 stores the relative positions transmitted from the plurality of asset terminals 100. In this case, the management server 300 stores the unique identifier of the asset terminal 100, the unique identifier of the reference terminal 200, and the relative positions in association with each other.

[0064] The management server 300 sets a reference position based on the asset position and the relative position (S130).

[0065] Referring to FIG. 13, the management server 300 detects asset locations and relative locations associated with the same reference terminal 200 (i.e., the unique identifier of the reference terminal 200) from among the stored asset locations and relative locations (S131).

[0066] The management server 300 extracts the midpoint between the two asset terminals 100 located at the opposite point with respect to the reference terminal 200 (S132). At this time, the management server 300 detects the position of each asset terminal 100, which is moved from the asset position in the direction of the relative position by the distance of the relative position. The reference position generation module 330 extracts, as the midpoint, a half point of the straight line connecting the positions of the two asset terminals 100 located at the opposite point from the detected positions.

[0067] Meanwhile, in step S132, the management server 300 may extract the midpoint using only the asset position. That is, the management server 300 detects the unique identifiers and asset positions of the asset terminals 100 linked to the unique identifier of the same reference terminal 200. The management server 300 extracts the midpoint between the two asset terminals 100 located at the opposite point with the reference terminal 200 as the reference. In this case, the management server 300 extracts the half point of the straight line connecting the asset positions of the two asset terminals 100 located at the opposite point with the reference terminal 200 as the center as the midpoint.

[0068] The management server 300 extracts the center point of the figure obtained by connecting the intermediate points detected in step S132, and generates it as a reference position (i.e., the position of the reference terminal 200) (S133). The management server 300 stores the reference position in association with the unique identifier of the reference terminal 200.

[0069] The management server 300 generates a corrected asset position by reflecting the relative position based on the reference position set in step S130 (S140). The management server 300 detects the unique identifier and relative position of the asset terminal 100 linked to the unique identifier of the reference terminal 200. The management server 300 places the asset terminal 100 by reflecting the relative position based on the reference position as a reference point, and generates a corrected asset position of each asset terminal 100. The management server 300 stores the unique identifier and the corrected asset position of the asset terminal 100 in association with each other.

[0070] The management server 300 displays the asset terminal 100 based on the stored corrected asset position (S150). That is, the management server 300 outputs the reference terminal 200 and the multiple asset terminals 100 on the screen, and at this time, displays the reference terminal 200 at the reference position and displays the asset terminal 100 at the corrected asset position.

[0071] As a result, the asset tracking method according to an embodiment of the present invention can reduce errors compared to the asset position measured based on a GPS signal, and although some errors occur with the actual position, the relative position based on the reference terminal 200 can be displayed in the same way, thereby improving the accuracy of asset tracking.

[0072] In a second embodiment of the present invention, multiple asset terminals are classified into groups, at least one master asset terminal is set in each group, and the exact location of the asset is tracked by correcting the asset location determined by GPS information using the relative positions of the master asset terminal and the slave asset terminal.

[0073] In other words, in the second embodiment of the present invention, a plurality of asset terminals are divided into a plurality of groups through UWB communication. The asset tracking system sets one of the asset terminals belonging to each group as a master asset terminal and sets the remaining asset terminals as slave asset terminals. The master asset terminal measures the relative position as position information through UWB communication with the slave asset terminals and transmits the measured position information at a set time interval to the management server. In this way, the asset tracking system grasps the relative position of the assets that is the same as the actual position.

[0074] To that end, referring to FIG. 14, the asset tracking system includes a plurality of asset terminals 400 a , 400 b and a management server 500 .

[0075] The asset terminals 400a, 400b are communication terminals attached (or installed) to the assets 10 for asset management. The asset terminals 400a, 400b are divided into a plurality of groups reflecting communication ranges, locations, etc. In this case, the asset terminals 400a, 400b communicate with each other through UWB communication to generate relative locations, and form one or more groups based on the relative locations.

[0076] The group thus configured includes two or more asset terminals 400a, 400b. One of the asset terminals 400a, 400b belonging to the same group acts as a master asset terminal 400a that serves as a reference for asset tracking, and the remaining asset terminals act as slave asset terminals 400b. In other words, the multiple asset terminals 400a, 400b are divided into one or more groups, and each group includes one master asset terminal 400a and multiple slave asset terminals 400b.

[0077] The master asset terminal 400a generates an asset position through GPS communication, and generates a relative position of the asset 10 in which the slave asset terminal 400b is installed through UWB communication with the slave asset terminal 400b belonging to the same group. Here, the relative position means the relative position of the slave asset terminal 400b based on the position of the master asset terminal 400a, and the relative position includes a direction and a distance.

[0078] The master asset terminal 400a transmits location information to the management server 500 at a set time interval or when requested by the management server 500. At this time, the master asset terminal 400a transmits location information to the management server 500, including an asset location, which is the location of the asset 10 where the master asset terminal 400a is installed, and the relative location of the asset 10 where the slave asset terminal 400b is installed.

[0079] On the other hand, if one asset terminal continues to operate as the master asset terminal 400a, the battery efficiency of the asset terminal will inevitably decrease. Therefore, the multiple asset terminals 400a, 400b change the master asset terminal 400a to another asset terminal according to the GPS communication quality, the UWB communication quality, the remaining battery power, etc. In other words, one of the slave asset terminals 400b is set as the new master asset terminal 400a, and the existing master asset terminal 400a is changed to the slave asset terminal 400b.

[0080] 15, the master asset terminal 400a includes a first communication module 410a, an asset position generating module 420a, a second communication module 430a, a relative position generating module 440a, a control module 450a, and a third communication module 460a. Here, the first communication module 410a is a GPS communication module that receives GPS signals from a satellite, the second communication module 430a is a UWB communication module that communicates with the slave asset terminal 400b belonging to the same group, and the third communication module 460a is a Sigfox communication module that communicates with the management server 500 and the slave asset terminal 400b belonging to the same group through low-power communication.

[0081] At this time, the master asset terminal 400a is the reference for relative position measurement, so the relative position generating module does not perform a separate operation. However, since the master asset terminal 400a may be changed to a slave asset terminal 400b later, the master asset terminal 400a includes a relative position generating module 420a similar to the slave asset terminal 400b described below.

[0082] The first communication module 410a receives a signal in the GPS frequency band (hereinafter, referred to as a GPS signal). The first communication module 410a transmits the received GPS signal to the asset position generating module 420a.

[0083] The asset position generating module 420a generates an asset position corresponding to the current position of the asset 10 based on the GPS signal transmitted from the first communication module 410a in response to an asset position generating request from the control module 450a. Here, since generating position information using a GPS signal is a common technique, detailed description thereof will be omitted.

[0084] The asset location generating module 420a generates a first location information transmission request including the asset location and a unique identifier of the master asset terminal 400a, and transmits the first location information transmission request to the control module 450a.

[0085] The second communication module 430a transmits and receives signals in the UWB frequency band (hereinafter, UWB signals) The second communication module 430a transmits and receives UWB signals to and from the slave asset terminal 400b belonging to the same group.

[0086] The second communication module 430a transmits and receives UWB signals to and from the second communication module 430b of the slave asset terminal 400b, and to this end, the second communication module 430a outputs an advertising signal or a position measurement request signal.

[0087] The second communication module 430a transmits a first UWB pulse to the slave asset terminal 400b in response to a ranging request signal from the slave asset terminal 400b. The second communication module 430a receives a second UWB pulse from the slave asset terminal 400b in response to the first UWB pulse. The second communication module 430a calculates a delay time between the first UWB pulse and the second UWB pulse. The second communication module 430a generates positioning information including a unique identifier and delay time of the slave asset terminal 400b and transmits the positioning information to the control module 450a.

[0088] The control module 450a transmits an asset location generation request to the asset location generation module 420a. The control module 450a receives first location information, which is location information generated based on a GPS signal, in response to the asset location generation request.

[0089] The control module 450a transmits a location information collection request to the third communication module 460a. The control module 450a receives the first location information and the second location information, which are responses to the location information collection request, from the third communication module 460a.

[0090] The control module 450a generates a location information transmission request including the first location information received from the asset location generation module 420a and the first and second location information received from the slave asset terminal 400b. In this case, the control module 450a may generate a first location information transmission request including the first location information and a second location information transmission request including the second location information. The control module 450a transmits the location information transmission request to the third communication module 460a.

[0091] The third communication module 460a transmits a relative position transmission request to a plurality of slave asset terminals 400b belonging to the same group in response to a request from the control module 450a. The third communication module 460a receives second position information in response to the relative position transmission request. In this case, the third communication module 460a receives the second position information including the unique identifier and the relative position of the slave asset terminal 400b. The third communication module 460a transmits the received second position information to the control module 450a.

[0092] In response to a location information transmission request from the control module 450a, the third communication module 460a transmits the first location information (asset locations of the master asset terminal 400a and the slave asset terminal 400b) and the second location information to the management server 500. The third communication module 460a converts the first location information and the second location information into a Sigfox protocol and transmits it to the management server 500.

[0093] 16, the slave asset terminal 400b includes a first communication module 410b, an asset position generating module 420b, a second communication module 430b, a relative position generating module 440b, a control module 450b, and a third communication module 460b. Here, the first communication module 410b is a GPS communication module that receives GPS signals from a satellite, the second communication module 430b is a UWB communication module that communicates with the slave asset terminal 400b belonging to the same group, and the third communication module 460b is a Sigfox communication module that communicates with the management server 500 and the slave asset terminal 400b belonging to the same group through low power communication.

[0094] The first communication module 410b receives a signal in the GPS frequency band (hereinafter, referred to as a GPS signal). The first communication module 410b transmits the received GPS signal to the asset position generation module 420b.

[0095] The asset position generation module 420b generates an asset position corresponding to the current position of the asset 10 based on the GPS signal transmitted from the first communication module 410b in response to an asset position generation request from the control module 450b. Since generating position information using a GPS signal is a common technique, detailed description thereof will be omitted.

[0096] The asset location generating module 420b generates a first location information transmission request including the asset location and a unique identifier of the slave asset terminal 400b, and transmits the first location information transmission request to the control module 450b.

[0097] The second communication module 430b transmits and receives signals in the UWB frequency band (hereinafter, UWB signals). The second communication module 430b transmits and receives UWB signals with the master asset terminal 400a belonging to the same group, and transmits the received information to the relative position generating module 440b.

[0098] The relative position generating module 440b transmits a positioning request to the second communication module 430b to request measurement of the relative position in response to the asset position generating request of the control module 450b. The relative position generating module 440b receives the delay time from the second communication module 430b, and generates the relative position of the slave asset terminal 400b based on the reference module based on the delay time. In this case, the relative position generating module 440b generates the relative position using positioning techniques such as TDoA (Time Difference of Arrival) and TWR (Two Way Ranging).

[0099] The relative position generating module 440b generates second position information including the relative position, the unique identifier of the master asset terminal 400a, and the unique identifier of the slave asset terminal 400b. The relative position generating module 440b transmits the second position information to the control module 450b.

[0100] The control module 450b transmits an asset location generation request to the asset location generation module 420b and the relative location generation module 440b. The control module 450b receives first location information and second location information in response to the asset location generation request. The control module 450b receives first location information, which is location information generated based on a GPS signal, from the asset location generation module 420b. The control module 450b receives second location information, which is relative location information generated based on a UWB signal, from the relative location generation module 440b.

[0101] The control module 450b generates a location information transmission request including the first location information and the second location information. In this case, the control module 450b may generate a first location information transmission request including the first location information and a second location information transmission request including the second location information. The control module 450b transmits the location information transmission request to the third communication module 460b.

[0102] The third communication module 460b transmits the first location information and the second location information to the master asset terminal 400a in response to the location information transmission request from the control module 450b. The third communication module 460b converts the first location information and the second location information into the Sigfox protocol and transmits it to the master asset terminal 400a.

[0103] The management server 500 collects position information from the master asset terminal 400a of each group. At this time, the management server 500 collects the asset position of the master asset terminal 400a belonging to the group, the asset position of the slave asset terminal 400b, and the relative position. The management server 500 corrects the asset position for each group using the relative position, and outputs the corrected asset position generated as the correction result.

[0104] To that end, referring to FIG. 17, the management server 500 includes a fourth communication module 510, a position information storage module 520, a reference position generation module 530, a correction module 540, and an output module 550.

[0105] The fourth communication module 510 receives first location information and second location information from a plurality of asset terminals 400a, 400b. The fourth communication module 510 receives the first location information including a unique identifier and an asset location of the master asset terminal 400a and / or a unique identifier and an asset location of the slave asset terminal 400b. The fourth communication module 510 receives the second location information including a unique identifier and a relative location of the slave asset terminal 400b and a unique identifier of the master asset terminal 400a. The fourth communication module 510 transmits a location information storage request including the first location information and the second location information to the location information storage module 520.

[0106] The location information storage module 520 stores the first location information and the second location information in response to a location information storage request from the fourth communication module 510. At this time, referring to Fig. 18, the location information storage module 520 stores the unique identifier of the master asset terminal 400a and the asset location in association with each other. The location information storage module 520 stores the unique identifier of the slave asset terminal 400b, the unique identifier of the master asset terminal 400a, the asset location, and the relative location in association with each other.

[0107] The location information storage module 520 detects the unique identifier and the reference location from the reference location storage request in response to the reference location storage request from the reference location generation module 530. The location information storage module 520 stores the reference location in association with the unique identifier of the slave asset terminal 400b that is the same as the detected unique identifier.

[0108] The location information storage module 520 detects the unique identifier and the corrected asset location from the asset location storage request in response to the asset location storage request from the correction module 540. The location information storage module 520 stores the corrected asset location in association with the unique identifier of the slave asset terminal 400b that is the same as the detected unique identifier.

[0109] The reference position generating module 530 generates a reference position of the slave asset terminal 400b based on the asset positions and the relative positions stored in the position information storing module 520.

[0110] The reference position generating module 530 detects information associated with the unique identifier of the same master asset terminal 400a from the position information storage module 520. The reference position generating module 530 detects the unique identifier, asset position, and relative position of the asset terminal 400 associated with the unique identifier of the same master asset terminal 400a.

[0111] The reference position generating module 530 extracts the midpoint of two asset terminals 400 located at opposite points with respect to the master asset terminal 400a. At this time, the reference position generating module 530 detects a position moved from the asset position in the direction of the relative position by the distance of the relative position for each asset terminal 400. The reference position generating module 530 extracts, as the midpoint, a half point of a straight line connecting the positions of the two asset terminals 400 located at opposite points from the detected positions.

[0112] Meanwhile, the reference position generating module 530 may generate the reference position of the master asset terminal 400a based on the asset position stored in the position information storage module 520. That is, the reference position generating module 530 may generate the asset position of the master asset terminal 400a as the reference position without performing a separate calculation.

[0113] The reference position generation module 530 detects information associated with the unique identifier of the same master asset terminal 400a from the position information storage module 520. The reference position generation module 530 detects the unique identifier and asset position of the asset terminal 400 associated with the unique identifier of the same master asset terminal 400a.

[0114] The reference position generating module 530 extracts the midpoint of two asset terminals 400 located at opposite points with the master asset terminal 400a as a reference. In this case, the reference position generating module 530 extracts a half point of a straight line connecting the asset positions of the two asset terminals 400 located at opposite points with the master asset terminal 400a as the center as the midpoint.

[0115] When the extraction of the intermediate points is completed, the reference position generating module 530 extracts the center point of the figure connecting the intermediate points and generates it as a reference position (i.e., the position of the master asset terminal 400a). The reference position generating module 530 generates a reference position storage request including the unique identifier and reference position of the master asset terminal 400a and transmits it to the position information storage module 520. The reference position generating module 530 transmits a position correction request including the unique identifier and reference position of the master asset terminal 400a to the correction module 540.

[0116] The correction module 540 generates a corrected asset position in response to the position correction request of the reference position generation module 530. That is, the correction module 540 detects the unique identifier and the reference position of the master asset terminal 400a from the position correction request. The correction module 540 detects the unique identifier and the relative position of the asset terminal 400 linked to the unique identifier of the master asset terminal 400a from the position information storage module 520. The correction module 540 uses the reference position as a reference point, positions the asset terminal 400 reflecting the relative position, and generates a corrected asset position of each asset terminal 400. The correction module 540 generates an asset position storage request including the unique identifier and the corrected asset position of the asset terminal 400 and transmits it to the position information storage module 520. The correction module 540 generates an asset output request and transmits it to the output module 550.

[0117] The output module 550 outputs the master asset terminal 400a and the multiple asset terminals 400a, 400b on a screen in response to an output request from the correction module 540. In this case, the output module 550 outputs a screen in which the master asset terminal 400a is displayed at the reference position and the asset terminal 400 is displayed at the corrected asset position.

[0118] An example in which the management server 500 corrects the positions of the asset terminals 400a and 400b will be described below with reference to FIGS.

[0119] First, as shown in FIG. 19, an example will be described in which the first asset terminal A1 to the seventh asset terminal A7 are stored in an open storage yard, the first asset terminal A1 is set as the master asset terminal 400a, and the second asset terminal A2 to the seventh asset terminal A7 are set as slave asset terminals 400b.

[0120] The second asset terminal A2 and the seventh asset terminal A7 are located at opposite points relative to the master asset terminal A1, the third asset terminal A3 and the sixth asset terminal A6 are located at opposite points relative to the master asset terminal A1, and the fourth asset terminal A4 and the fifth asset terminal A5 are located at opposite points relative to the master asset terminal A1.

[0121] Referring to FIG. 20, the asset positions A2' to A7' collected from the asset terminal 400 are generated based on GPS signals, and therefore are displayed differently from the actual positions, and the relative positions between the asset terminals 400 are also displayed differently from the actual positions.

[0122] To correct this, the management server 500 sets a reference position corresponding to the position of the master asset terminal 400a.

[0123] 21, the management server 500 detects, for each asset terminal 400, a position moved from the asset position in the direction of the relative position by the distance of the relative position as the asset position.

[0124] The management server 500 extracts the midpoint at a half point of a straight line connecting the asset positions of two asset terminals 400 located at opposite points with respect to the master asset terminal 400a. In this case, A, which is the center point between the second asset terminal A2 and the seventh asset terminal A7, B, which is the center point between the third asset terminal A3 and the sixth asset terminal A6, and C, which is the center point between the fourth asset terminal A4 and the fifth asset terminal A5, are extracted.

[0125] The management server 500 extracts the center point D of the triangle formed by connecting the extracted intermediate points A, B, and C, and generates this as the reference position (A1'', that is, the position of the master asset terminal 400a).

[0126] On the other hand, referring to FIG. 22, the management server 500 may extract the half points of a straight line connecting the asset positions (asset positions not reflecting the relative positions) of two asset terminals 400 located at opposite points based on the master asset terminal 400a as midpoints A, B, and C.

[0127] Referring to Figure 23, the management server 500 sets the reference position A1'' as the position of the master asset terminal 400a, arranges each asset terminal 400 to reflect the relative position of the asset terminal 400 based on the reference position A1'', and generates corrected asset positions A2'' to A7'' for each asset terminal 400.

[0128] As a result, as shown in FIG. 24, the corrected asset positions A2″ to A7″ generated by the management server 500 can reduce errors compared to the asset positions A2′ to A7′ measured based on the GPS signal, and although there is an error with the actual positions A2 to A7, the relative positions based on the master asset terminal 400a can be displayed in the same way, thereby improving the accuracy of asset tracking.

[0129] Hereinafter, an asset tracking method according to an embodiment of the present invention will be described with reference to the drawings.

[0130] 25, a plurality of slave asset terminals 400b form one or more groups through mutual communication (S210). In this case, the plurality of slave asset terminals 400b measure relative distances through mutual UWB communication and form one or more groups based on the relative distances, as an example.

[0131] One of the slave asset terminals 400b belonging to each group is set as a master asset terminal 400a, and the rest are set as slave asset terminals 400b (S220). At this time, the asset terminals 400a and 400b set the master asset terminal 400a in consideration of the remaining battery level, communication range, quality, etc., as an example.

[0132] The management server 500 collects asset positions, which are GPS-based position information, from the master asset terminal 400a of each group (S230). A plurality of slave asset terminals 400b measure asset positions based on GPS signals and transmit them to the master asset terminal 400a belonging to the same group. The master asset terminal 400a of each group transmits the asset positions to the management server 500 in response to a request from the management server 500. The management server 500 stores the asset positions transmitted from the master asset terminal 400a. At this time, the management server 500 stores the unique identifier of the slave asset terminal 400b in association with the asset positions.

[0133] The management server 500 collects relative positions, which are position information based on UWB, from the master asset terminal 400a of each group (S240). The master asset terminal 400a performs UWB communication with the slave asset terminal 400b of the same group to measure the relative position of the slave asset terminal 400b based on the master asset terminal 400a, and transmits the relative position to the management server 500 at the request of the management server 500. The management server 500 stores the relative position transmitted from the master asset terminal 400a. At this time, the management server 500 stores the unique identifier and relative position of the slave asset terminal 400b in association with the unique identifier of the master asset terminal 400a.

[0134] The management server 500 sets a reference position based on the asset position and the relative position (S250).

[0135] Referring to FIG. 26, the management server 500 detects asset locations and relative locations associated with the same master asset terminal 400a (i.e., the unique identifier of the master asset terminal 400a) from among the stored asset locations and relative locations (S251).

[0136] The management server 500 extracts the midpoint between the two slave asset terminals 400b located at the opposite point with respect to the master asset terminal 400a (S252). At this time, the management server 500 detects a position for each slave asset terminal 400b that is moved from the asset position in the direction of the relative position by the distance of the relative position. The reference position generation module 530 extracts, as the midpoint, a half point of a straight line connecting the positions of the two slave asset terminals 400b located at the opposite point from the detected positions.

[0137] Meanwhile, in step S252, the management server 500 may extract the midpoint using only the asset position. That is, the management server 500 detects the unique identifier and asset position of the slave asset terminal 400b linked to the unique identifier of the same master asset terminal 400a. The management server 500 extracts the midpoint of two slave asset terminals 400b located at opposite points based on the master asset terminal 400a. In this case, the management server 500 extracts, as the midpoint, a half point of a straight line connecting the asset positions of the two slave asset terminals 400b located at opposite points with the master asset terminal 400a at the center.

[0138] The management server 500 extracts the center point of the figure obtained by connecting the intermediate points detected in step S252, and generates this as a reference position (i.e., the position of the master asset terminal 400a) (S253). The management server 500 stores the reference position in association with the unique identifier of the master asset terminal 400a.

[0139] The management server 500 generates a corrected asset position by reflecting the relative position based on the reference position set in step S250 (S260). The management server 500 detects the unique identifier and relative position of the slave asset terminal 400b linked to the unique identifier of the master asset terminal 400a. The management server 500 places the slave asset terminal 400b by reflecting the relative position based on the reference position as a reference point, and generates a corrected asset position of each slave asset terminal 400b. The management server 500 stores the unique identifier and corrected asset position of the slave asset terminal 400b in association with each other.

[0140] The management server 500 displays the master asset terminal 400a and the slave asset terminal 400b based on the stored corrected asset position (S270). That is, the management server 500 outputs the master asset terminal 400a and the multiple slave asset terminals 400b on the screen, and at this time, displays the master asset terminal 400a at the reference position and displays the slave asset terminals 400b at the corrected asset position.

[0141] On the other hand, if the asset terminal set as the master asset terminal 400a in step S220 continues to operate as the master asset terminal 400a, the battery efficiency of the asset terminal will inevitably decrease. Therefore, the multiple asset terminals 400a, 400b change the master asset terminal 400a to another asset terminal according to the GPS communication quality, the UWB communication quality, the remaining battery power, etc. In other words, one of the slave asset terminals 400b is set as the new master asset terminal 400a, and the existing master asset terminal 400a is changed to the slave asset terminal 400b.

[0142] As a result, the asset tracking method according to an embodiment of the present invention can reduce errors compared to the asset position measured based on a GPS signal, and although some errors occur with the actual position, the relative position based on the master asset terminal 400a can be displayed in the same way, thereby improving the accuracy of asset tracking.

[0143] In a third embodiment of the present invention, a plurality of asset terminals are classified into groups, and the position of the master asset terminal of each group is set as a reference position, and the asset positions are set using the relative positions of the slave asset terminals, thereby accurately tracking the relative positions between assets. In this case, the asset tracking system and method according to the third embodiment of the present invention can extend the position tracking period of assets loaded for a long time by driving the GPS communication module of the master asset terminal and stopping the driving of the GPS communication module of the slave asset terminal.

[0144] In other words, in the third embodiment of the present invention, a plurality of asset terminals are divided into a plurality of groups by UWB communication, and one of the asset terminals belonging to each group is set as a master asset terminal, and the remaining asset terminals are set as slave asset terminals. The master asset terminal measures the relative position as position information by UWB communication with the slave asset terminals, and transmits the measured position information at a set time interval to the management server. In this way, the asset tracking system grasps the relative position of the assets that is the same as the actual position.

[0145] 27, in a conventional asset tracking system, a plurality of asset terminals each measure the asset position and transmit the asset position to a management server. In this case, the asset terminal needs to keep the GPS module and the low-power communication module in a constantly operating state in order to measure the asset position and transmit the asset position to the management server, which inevitably reduces the efficiency of the battery mounted in the asset terminal.

[0146] Furthermore, when an asset is loaded for a long period of time, the asset terminal may become unable to measure the location of the asset due to a decrease in battery efficiency.

[0147] Therefore, in an asset tracking system and method according to an embodiment of the present invention, multiple asset terminals are divided into multiple groups, and one of the asset terminals belonging to each group is set as a master asset terminal, and the remaining asset terminals are set as slave asset terminals.

[0148] The master asset terminal measures the asset position based on GPS communication and transmits it to the management server, and collects the relative positions based on UWB communication from the slave asset terminals and transmits them to the management server. At this time, the slave asset terminal stops measuring the asset position based on GPS communication and measures the relative position based on the master asset terminal through UWB communication with the master asset terminal.

[0149] The management server arranges the slave asset terminals so as to reflect the relative positions of the slave asset terminals based on the asset position of the master asset terminal, thereby accurately grasping the relative positions of the assets.

[0150] To this end, referring to FIG. 28, the asset tracking system includes a plurality of asset terminals 600 a , 600 b and a management server 700 .

[0151] The asset terminals 600a, 600b are communication terminals attached (or installed) to the assets 10, respectively, for managing the assets 10. The asset terminals 600a, 600b are divided into a plurality of groups reflecting communication ranges, locations, etc. In this case, the asset terminals 600a, 600b communicate with each other through UWB communication to generate relative locations, and form one or more groups based on the relative locations.

[0152] The group thus configured includes two or more asset terminals 600a, 600b. One of the asset terminals 600a, 600b belonging to the same group acts as a master asset terminal 600a that serves as a reference for asset tracking, and the remaining asset terminals act as slave asset terminals 600b. In other words, the multiple asset terminals 600a, 600b are divided into one or more groups, and each group includes one master asset terminal 600a and multiple slave asset terminals 600b.

[0153] The master asset terminal 600a generates an asset position through GPS communication, and generates a relative position of the asset 10 on which the slave asset terminal 600b is installed through UWB communication with the slave asset terminal 600b belonging to the same group. Here, the relative position means the relative position of the slave asset terminal 600b based on the position of the master asset terminal 600a, and the relative position includes a direction and a distance.

[0154] The master asset terminal 600a transmits location information to the management server 700 at a set time interval or when requested by the management server 700. At this time, the master asset terminal 600a transmits location information to the management server 700, including an asset location, which is the location of the asset 10 where the master asset terminal 600a is installed, and the relative location of the asset 10 where the slave asset terminal 600b is installed.

[0155] On the other hand, if one asset terminal continues to operate as the master asset terminal 600a, the battery efficiency of the asset terminal will inevitably decrease. Therefore, the multiple asset terminals 600a, 600b change the master asset terminal 600a to another asset terminal according to the GPS communication quality, the UWB communication quality, the remaining battery power, etc. In other words, one of the slave asset terminals 600b is set as the new master asset terminal 600a, and the existing master asset terminal 600a is changed to the slave asset terminal 600b.

[0156] 29, the master asset terminal 600a includes a first communication module 610a, an asset position generating module 620a, a second communication module 630a, a relative position generating module 640a, a control module 650a, and a third communication module 660a. Here, the first communication module 610a is a GPS communication module that receives GPS signals from a satellite, the second communication module 630a is a UWB communication module that communicates with the slave asset terminal 600b belonging to the same group, and the third communication module 660a is a Sigfox communication module that communicates with the management server 700 and the slave asset terminal 600b belonging to the same group through low power communication.

[0157] At this time, the master asset terminal 600a is the reference for relative position measurement, so the relative position generating module does not perform a separate operation. However, since the master asset terminal 600a may be changed to a slave asset terminal 600b later, the master asset terminal 600a includes a relative position generating module 640a similar to the slave asset terminal 600b described below.

[0158] The first communication module 610a receives a signal in the GPS frequency band (hereinafter, referred to as a GPS signal). The first communication module 610a transmits the received GPS signal to the asset position generating module 620a.

[0159] The asset position generation module 620a generates an asset position corresponding to the current position of the asset 10 based on the GPS signal transmitted from the first communication module 610a in response to an asset position generation request from the control module 650a. Since generating position information using a GPS signal is a common technique, detailed description thereof will be omitted.

[0160] The asset location generating module 620a generates a first location information transmission request including the asset location and a unique identifier of the master asset terminal 600a, and transmits the first location information transmission request to the control module 650a.

[0161] The second communication module 630a transmits and receives signals in the UWB frequency band (hereinafter, UWB signals) The second communication module 630a transmits and receives UWB signals to and from the slave asset terminal 600b belonging to the same group.

[0162] The second communication module 630a transmits and receives UWB signals to and from the second communication module 630b of the slave asset terminal 600b, and for this purpose, the second communication module 630a outputs an advertising signal or a position measurement request signal.

[0163] The second communication module 630a transmits a first UWB pulse to the slave asset terminal 600b in response to a ranging request signal from the slave asset terminal 600b. The second communication module 630a receives a second UWB pulse from the slave asset terminal 600b in response to the first UWB pulse. The second communication module 630a calculates a delay time between the first UWB pulse and the second UWB pulse. The second communication module 630a generates positioning information including a unique identifier and delay time of the slave asset terminal 600b and transmits the positioning information to the control module 650a.

[0164] The control module 650a transmits an asset location generation request to the asset location generation module 620a. The control module 650a receives first location information, which is location information generated based on a GPS signal, in response to the asset location generation request.

[0165] The control module 650a transmits a location information collection request to the third communication module 660a. The control module 650a receives second location information, which is a response to the location information collection request, from the third communication module 660a.

[0166] The control module 650a generates a location information transmission request including the first location information received from the asset location generation module 620a and the second location information received from the slave asset terminal 600b. In this case, the control module 650a may generate a first location information transmission request including the first location information and a second location information transmission request including the second location information. The control module 650a transmits the location information transmission request to the third communication module 660a.

[0167] The third communication module 660a transmits a relative position transmission request to a plurality of slave asset terminals 600b belonging to the same group in response to a request from the control module 650a. The third communication module 660a receives second position information in response to the relative position transmission request. In this case, the third communication module 660a receives the second position information including the unique identifier and the relative position of the slave asset terminal 600b. The third communication module 660a transmits the received second position information to the control module 650a.

[0168] In response to a location information transmission request from the control module 650a, the third communication module 660a transmits the first location information (i.e., the asset location of the master asset terminal 600a) and the second location information (i.e., the relative location of the slave asset terminal 600b) to the management server 700. The third communication module 660a converts the first location information and the second location information into the Sigfox protocol and transmits them to the management server 700.

[0169] 30, the slave asset terminal 600b includes a first communication module 610b, an asset position generating module 620b, a second communication module 630b, a relative position generating module 640b, a control module 650b, and a third communication module 660b. Here, the first communication module 610b is a GPS communication module that receives GPS signals from a satellite, the second communication module 630b is a UWB communication module that communicates with the slave asset terminal 600b belonging to the same group, and the third communication module 660b is a Sigfox communication module that communicates with the management server 700 and the slave asset terminal 600b belonging to the same group through low power communication.

[0170] The first communication module 610b and the asset location generation module 620b are set to a sleep mode and stop receiving GPS signals and generating asset locations, i.e., the first communication module 610b and the asset location generation module 620b stop operating in response to a stop request from the control module 650b.

[0171] The second communication module 630b transmits and receives signals in the UWB frequency band (hereinafter, UWB signals). The second communication module 630b transmits and receives UWB signals with the master asset terminal 600a belonging to the same group, and transmits the received information to the relative position generating module 640b.

[0172] The relative position generating module 640b transmits a positioning request to the second communication module 630b to request measurement of the relative position in response to the asset position generating request of the control module 650b. The relative position generating module 640b receives the delay time from the second communication module 630b, and generates the relative position of the slave asset terminal 600b based on the reference module based on the delay time. In this case, the relative position generating module 640b generates the relative position using positioning techniques such as TDoA (Time Difference of Arrival) and TWR (Two Way Ranging).

[0173] The relative position generating module 640b generates second position information including the relative position, the unique identifier of the master asset terminal 600a, and the unique identifier of the slave asset terminal 600b. The relative position generating module 640b transmits the second position information to the control module 650b.

[0174] When the asset terminal is set as a slave asset terminal 600b, the control module 650b transmits a stop request to the first communication module 610b and the asset position generating module 620b. That is, when the asset terminal operates in a slave mode, the control module 650b stops the first communication module 610b and the asset position generating module 620b to prevent unnecessary consumption of the battery built in the asset terminal. In this case, when the asset terminal is changed to a master mode, the control module 650b transmits a restart request to the first communication module 610b and the asset position generating module 620b.

[0175] The control module 650b transmits an asset location generation request to the relative location generation module 640b. The control module 650b receives second location information generated by the relative location generation module 640b in response to the asset location generation request, where the second location information is relative location information generated based on the UWB signal.

[0176] The control module 650b generates a location information transmission request including the second location information, and transmits the location information transmission request to the third communication module 660b.

[0177] The third communication module 660b transmits the second location information to the master asset terminal 600a in response to the location information transmission request from the control module 650b. The third communication module 660b converts the second location information into Sigfox protocol and transmits it to the master asset terminal 600a.

[0178] The management server 700 collects location information from the master asset terminal 600a of each group. At this time, the management server 700 collects the asset location of the master asset terminal 600a belonging to the group and the relative location of the slave asset terminal 600b. The management server 700 arranges the slave asset terminals 600b for each group, reflecting the relative location of each slave asset terminal 600b based on the asset location of the master asset terminal 600a.

[0179] To that end, referring to FIG. 31, the management server 700 includes a fourth communication module 710, a position information storage module 720, a reference position generation module 730, a correction module 740, and an output module 750.

[0180] The fourth communication module 710 receives first location information and second location information from a plurality of asset terminals 600a, 600b. The fourth communication module 710 receives the first location information including a unique identifier and an asset location of the master asset terminal 600a, and the second location information including a unique identifier and a relative location of the slave asset terminal 600b. The fourth communication module 710 transmits a location information storage request including the first location information and the second location information to the location information storage module 720.

[0181] The location information storage module 720 stores the first location information and the second location information in response to a location information storage request from the fourth communication module 710. At this time, referring to Fig. 32, the location information storage module 720 stores the unique identifier and the asset location of the master asset terminal 600a in association with each other. The location information storage module 720 stores the unique identifier of the slave asset terminal 600b, the unique identifier and the relative location of the master asset terminal 600a in association with each other.

[0182] The location information storage module 720 detects the unique identifier and the reference location from the reference location storage request in response to the reference location storage request from the reference location generation module 730. The location information storage module 720 stores the reference location by linking the detected unique identifier to the slave asset terminal 600b linked to the unique identifier of the same master reference terminal 600a.

[0183] The location information storage module 720 detects the unique identifier and the corrected asset location from the asset location storage request in response to the asset location storage request from the correction module 740. The location information storage module 720 stores the corrected asset location in association with the unique identifier of the slave asset terminal 600b that is the same as the detected unique identifier.

[0184] The reference position generating module 730 generates the asset position of the master asset terminal 600a stored in the position information storing module 720 as a reference position of the slave asset terminal 600b. The reference position generating module 730 generates a reference position storage request including the unique identifier and reference position of the master asset terminal 600a and transmits it to the position information storing module 720. The reference position generating module 730 transmits a position correction request including the unique identifier and reference position of the master asset terminal 600a to the correction module 740.

[0185] The correction module 740 generates a corrected asset position in response to the position correction request from the reference position generation module 730. That is, the correction module 740 detects the unique identifier, the reference position, and the relative position of the slave asset terminal 600b from the position correction request.

[0186] The correction module 740 places the master asset terminal 600a at a reference position, places the slave asset terminal 600b by reflecting a relative position with the reference position as a reference point, and generates a corrected asset position of the slave asset terminal 600b. The correction module 740 generates an asset position storage request including the unique identifier of the asset terminal 600 and the corrected asset position, and transmits it to the position information storage module 720. The correction module 740 generates an asset output request and transmits it to the output module 750.

[0187] The output module 750 outputs the master asset terminal 600a and the multiple asset terminals 600a, 600b on a screen in response to an output request from the correction module 740. At this time, the output module 750 outputs a screen in which the master asset terminal 600a is displayed at the reference position and the asset terminal 600 is displayed at the corrected asset position.

[0188] Referring to FIG. 33, it is assumed that the first asset terminal A1 to the seventh asset terminal A7 are stored in an open storage yard, the first asset terminal A1 is set as the master asset terminal 600a, and the second asset terminal A2 to the seventh asset terminal A7 are set as slave asset terminals 600b.

[0189] In this case, as shown in Fig. 34, the asset position of the master asset terminal A1' is generated by GPS communication, and therefore there is a difference from the actual position due to GPS error. However, since the positions of the slave asset terminals A2 to A7 are corrected to reflect the relative positions of the slave asset terminals A2 to A7 based on the asset position of the master asset terminal A1', the relative positions between the assets can be accurately tracked.

[0190] Hereinafter, an asset tracking method according to an embodiment of the present invention will be described with reference to the drawings.

[0191] 35, a plurality of slave asset terminals 600b form one or more groups through mutual communication (S310). In this case, the plurality of slave asset terminals 600b measure relative distances through mutual UWB communication and form one or more groups based on the relative distances, as an example.

[0192] One of the slave asset terminals 600b belonging to each group is set as a master asset terminal 600a, and the rest are set as slave asset terminals 600b (S320). In this case, the asset terminals 600a and 600b set the master asset terminal 600a in consideration of the remaining battery level, communication range, quality, etc., as an example.

[0193] The slave asset terminal 600b stops measuring the asset position (S330). That is, the slave asset terminal 600b sets the first communication module 610b, which is a GPS communication module, and the asset position generation module 620b to a sleep mode, and stops receiving GPS signals and generating asset positions. This improves the efficiency of the battery installed in the slave asset terminal 600b, and extends the period during which the position of the loaded asset can be tracked for a long time.

[0194] The management server 700 collects asset positions, which are GPS-based position information, from the master asset terminal 600a of each group (S340). The master asset terminal 600a of each group measures the asset position based on the GPS signal and transmits the asset position to the management server 700 in response to a request from the management server 700. The management server 700 stores the asset position transmitted from the master asset terminal 600a. At this time, the management server 700 stores the unique identifier of the master asset terminal 600a in association with the asset position.

[0195] The management server 700 collects relative positions, which are position information based on UWB, from the master asset terminal 600a of each group (S350). The master asset terminal 600a performs UWB communication with the slave asset terminal 600b of the same group to measure the relative position of the slave asset terminal 600b based on the master asset terminal 600a, and transmits the relative position to the management server 700 at the request of the management server 700. The management server 700 stores the relative position transmitted from the master asset terminal 600a. At this time, the management server 700 stores the unique identifier and relative position of the slave asset terminal 600b in association with the unique identifier of the master asset terminal 600a.

[0196] The management server 700 sets the asset position of the master asset terminal 600a as a reference position (S360). The management server 700 stores the reference position in association with the unique identifier of the master asset terminal 600a.

[0197] The management server 700 generates a corrected asset position of the slave asset terminal 600b by reflecting the relative position based on the reference position set in step S360 (S370). The management server 700 detects the unique identifier and relative position of the slave asset terminal 600b linked to the unique identifier of the master asset terminal 600a. The management server 700 places the slave asset terminal 600b by reflecting the relative position based on the reference position as a reference point, and generates a corrected asset position of each slave asset terminal 600b. The management server 700 stores the unique identifier and corrected asset position of the slave asset terminal 600b in association with each other.

[0198] The management server 700 displays the master asset terminal 600a and the slave asset terminal 600b based on the stored corrected asset position (S380). That is, the management server 700 outputs the master asset terminal 600a and the multiple slave asset terminals 600b on the screen, and at this time, displays the master asset terminal 600a at the reference position and displays the slave asset terminals 600b at the corrected asset positions.

[0199] On the other hand, if the asset terminal set as the master asset terminal 600a in step S320 continues to operate as the master asset terminal 600a, the battery efficiency of the asset terminal will inevitably decrease. Therefore, the multiple asset terminals 600a, 600b change the master asset terminal 600a to another asset terminal according to the GPS communication quality, the UWB communication quality, the remaining battery power, etc. In other words, one of the slave asset terminals 600b is set as the new master asset terminal 600a, and the existing master asset terminal 600a is changed to the slave asset terminal 600b.

[0200] As a result, the asset tracking method according to an embodiment of the present invention can accurately track the relative positions of assets, improve the efficiency of the battery installed in the asset terminal, and extend the period during which the position of assets loaded for long periods of time can be tracked.

[0201] Although the preferred embodiment of the present invention has been described above, it is understood that the present invention can be modified in various forms, and that a person having ordinary skill in the art can implement various modifications and alterations without departing from the technical scope of the present invention. [Explanation of symbols]

[0202] 10 Assets 100, 400 Asset Terminal 110, 410a, 410b, 610a, 610b First communication module 120, 420a, 420b, 620a, 620b Asset location generation module 130, 430a, 430b, 630a, 630b Second communication module 140, 440a, 440b, 640a, 640b Relative position generation module 150, 450a, 450b, 650a, 650b Control Module 160, 460a, 460b, 660a, 660b Third communication module 200 Reference Terminal 300, 500, 700 Management Server 310, 510, 710 4th communication module 320, 520, 720 Location information storage module 330, 530, 730 Reference Position Generation Module 340, 540, 740 Compensation Module 350, 550, 750 Output Module 400a, 600a Master Asset Terminal 400b, 600b Slave Asset Terminal

Claims

1. A reference terminal; A plurality of asset terminals are installed on assets to be tracked, and perform UWB communication with the reference terminal to measure relative positions with respect to the reference terminal; a management server that collects asset positions and relative positions from the plurality of asset terminals and corrects the asset positions of the asset terminals using the relative positions; The plurality of asset terminals generate relative positions by UWB communication among each other, and configure one or more groups including one master asset terminal and a plurality of slave asset terminals based on the relative positions; Based on at least one of GPS communication quality, UWB communication quality, and battery remaining amount, one of the plurality of slave asset terminals included in the first group is set as a master asset terminal of the first group, and an existing master asset terminal of the first group is set as a slave asset terminal of the first group; The slave asset terminals are installed on assets to be tracked, measure asset positions based on GPS signals, and perform UWB communication with the master asset terminal to measure relative positions based on the master asset terminal; The master asset terminal is the reference terminal, which is installed on the asset to be tracked, measures the asset position based on a GPS signal, and collects the asset position and the relative position from the plurality of slave asset terminals belonging to the same group; An asset tracking system, wherein the management server collects asset positions and relative positions of the plurality of slave asset terminals from the master asset terminal, and corrects the asset positions using the relative positions.

2. The plurality of asset terminals include a first communication module for receiving GPS signals; an asset location generating module that generates an asset location corresponding to a current location of an asset based on a GPS signal received by the first communication module, and generates first location information including the asset location and a unique identifier of the asset terminal; a second communication module for transmitting and receiving UWB signals to and from the reference terminal and receiving a delay time of the UWB signals; A relative position generating module that generates a relative position including a direction and a distance from the reference terminal based on the UWB signal and the delay time received by the second communication module, and generates second position information including the relative position and a unique identifier of the asset terminal; a control module that collects the first location information generated by the asset location generating module and the second location information generated by the relative location generating module, and transmits a location information transmission request including at least one of the first location information and the second location information; and a third communication module for converting the first location information and the second location information into a Sigfox protocol in response to a location information transmission request from the control module and then transmitting the converted location information to the management server.

3. The management server includes: a fourth communication module that receives first location information and second location information from the plurality of asset terminals and outputs a location information storage request including the first location information and the second location information; a location information storage module that stores, in response to a location information storage request from the fourth communication module, a unique identifier of the asset terminal, a unique identifier of a reference terminal, an asset location, and a relative location detected from the first location information and the second location information in association with each other; a reference position generating module that generates a reference position corresponding to the position of the reference terminal based on the asset position and the relative position stored in the position information storage module, and outputs a position correction request including the reference position and a unique identifier of the reference terminal; a correction module that detects a unique identifier and a relative position of an asset terminal associated with the unique identifier of the reference terminal in response to a position correction request from the reference position generation module, and generates a position corresponding to a direction and a distance of the relative position from the reference point as a corrected asset position of the asset terminal, using the reference position as a reference point; The reference position generating module includes: Extracting a midpoint between two asset terminals located at opposite points with respect to the reference terminal, and generating a center point of a figure connecting the extracted midpoints as the reference position; The asset tracking system according to claim 1, characterized in that one of the following points is extracted as the midpoint: 1 / 2 point of a line connecting the asset positions of two asset terminals, and 1 / 2 point of a line connecting positions moved from the asset positions of the two asset terminals in the direction of the relative position by the distance of the relative position.

4. The master asset terminal comprises: a first communication module for receiving GPS signals; an asset location generating module that generates an asset location corresponding to a current location of an asset based on a GPS signal received by the first communication module, and generates first location information including the asset location and a unique identifier of the asset terminal; a second communication module for transmitting and receiving UWB signals to the plurality of slave asset terminals, outputting one of an advertising signal and a position measurement request signal to the slave asset terminal, transmitting a first UWB Pulse to an asset terminal that has transmitted a ranging request signal, receiving a second UWB Pulse from the asset terminal, measuring a delay time between the first UWB Pulse and the second UWB Pulse, and transmitting the measured delay time to the slave asset terminal; a control module that transmits an asset location generation request to the asset location generation module, receives the first location information in response to the asset location generation request, transmits a location information collection request, receives asset locations and relative locations of the slave asset terminals in response to the location information collection request, and transmits a location information transmission request including the first location information and the asset locations and relative locations of the slave asset terminals; and a third communication module that, in response to a location information collection request from the control module, collects asset positions and relative positions from the slave asset terminals belonging to the same group and transmits them to the control module, and, in response to a location information transmission request from the control module, converts the first location information and the asset positions and relative positions of the slave asset terminals into a Sigfox protocol and transmits them to the management server.

5. The plurality of slave asset terminals include a first communication module for receiving GPS signals; an asset location generating module that generates an asset location corresponding to a current location of an asset based on a GPS signal received by the first communication module, and generates first location information including the asset location and a unique identifier of a slave asset terminal; A second communication module for transmitting and receiving UWB signals with the master asset terminal and receiving a delay time of the UWB signals; A relative position generating module that generates a relative position including a direction and a distance from the master asset terminal based on the UWB signal and the delay time received by the second communication module, and generates second position information including the relative position and a unique identifier of the slave asset terminal; a control module that collects the first location information generated by the asset location generating module and the second location information generated by the relative location generating module, and transmits a location information transmission request including at least one of the first location information and the second location information; and a third communication module that converts the first location information and the second location information into a Sigfox protocol in response to a location information transmission request from the control module and then transmits the converted location information to the master asset terminal.

6. The management server includes: a fourth communication module that receives first location information and asset locations and relative locations of the plurality of slave asset terminals from a master asset terminal, and outputs a location information storage request including the first location information and the asset locations and relative locations of the plurality of slave asset terminals; a location information storage module that stores the first location information and asset locations and relative locations of the slave asset terminals in response to a location information storage request from the fourth communication module; a reference position generating module that generates a reference position corresponding to the position of the master asset terminal based on the asset position and the relative position stored in the position information storage module, and outputs a position correction request including the reference position and a unique identifier of the master asset terminal; and a correction module that detects a unique identifier and a relative position of a slave asset terminal associated with the unique identifier of the master asset terminal in response to a position correction request from the reference position generation module, and generates a position corresponding to the direction and distance of the relative position from the reference point as a corrected asset position of the slave asset terminal using the reference position as a reference point.

7. The plurality of asset terminals generate relative positions by UWB communication among each other, and configure one or more groups including a master asset terminal and a plurality of slave asset terminals based on the relative positions; The plurality of slave asset terminals are installed on assets to be tracked, and perform UWB communication with a master asset terminal belonging to the same group to measure relative positions based on the master asset terminal; The master asset terminal is the reference terminal, which is installed on the asset to be tracked, measures the asset position based on a GPS signal, and collects relative positions from the slave asset terminals belonging to the same group; The asset tracking system of claim 1, wherein the management server collects the asset position of the master asset terminal and the relative positions of the plurality of slave asset terminals from the master asset terminal of each group, sets the asset position as a reference position, and generates corrected asset positions of the plurality of slave asset terminals by reflecting the relative positions in the asset positions based on the reference position.

8. The plurality of asset terminals include a first communication module for receiving GPS signals; an asset location generating module that generates an asset location corresponding to a current location of an asset based on a GPS signal received by the first communication module, and generates first location information including the asset location and a unique identifier of the asset terminal; The asset tracking system of claim 7, wherein an asset terminal that is set as a slave asset terminal among the plurality of asset terminals sets the first communication module and the asset position generation module to a sleep mode to discontinue generating the asset position.

9. The asset tracking system according to claim 7 , wherein the management server generates a position moved from the reference position in a direction of the relative position by a distance of the relative position as a corrected asset position of the slave asset terminal.

10. 1. An asset tracking method performed by a management server capable of communicating with a reference terminal and a plurality of asset terminals, comprising: collecting asset locations generated based on GPS signals from the plurality of asset terminals; Collecting relative positions based on the reference terminal from the plurality of asset terminals, the relative positions being generated by UWB communication between the reference terminal and the asset terminal; generating a reference position corresponding to a position of the reference terminal based on the asset positions collected in the step of collecting the asset positions; and generating a corrected asset position by reflecting the relative position based on the reference position generated in the step of generating the reference position. In the step of generating the reference position, A midpoint between two asset terminals located at opposite points based on the reference terminal is extracted, and one of a half point of a straight line connecting asset positions of the two asset terminals located at opposite points based on the reference terminal and a half point of a straight line connecting positions moved by a distance of the relative position from the asset positions of the two asset terminals located at opposite points based on the reference terminal is extracted as the midpoint; An asset tracking method comprising the steps of: generating, as the reference position, a center point of a figure obtained by connecting the extracted intermediate points.

11. In the step of generating the corrected asset location, The method for tracking assets according to claim 10, further comprising the step of generating, as the corrected asset position, a position moved from the reference point in a direction toward the relative position by a distance of the relative position, the reference position being used as a reference point.

12. forming one or more groups by communication between a plurality of asset terminals; A step of setting a master asset terminal and a plurality of slave asset terminals of each group by the asset terminals belonging to each group in the step of forming the group; a step of deactivating a GPS communication module by the asset terminal that is set as a slave asset terminal in the setting step; collecting, by a management server, from a master asset terminal of each group, one of asset positions of the slave asset terminals generated based on GPS signals and an asset position of the master asset terminal; collecting, by a management server, from a master asset terminal of each group, relative positions of the plurality of slave asset terminals with respect to the master asset terminal; setting a reference position based on the asset positions of the master asset terminal collected by the management server in the step of collecting the asset positions; and generating, by the management server, corrected asset positions of the plurality of slave asset terminals by reflecting the relative positions based on the reference positions generated in the step of generating the reference positions; In the stopping step, the asset tracking method further comprises setting an asset terminal that is set as the slave asset terminal among the plurality of asset terminals to a sleep mode and suspending reception of GPS signals and generation of asset positions.

13. The method further comprises the step of collecting, by the master asset terminal, asset positions and relative positions from the plurality of slave asset terminals prior to the step of collecting the relative positions; 13. The method of claim 12, wherein the relative locations of the plurality of slave asset terminals are generated by UWB communication of the master asset terminal and the plurality of slave asset terminals.

14. The asset tracking method according to claim 12, wherein in the step of forming the group, relative positions are generated by UWB communication between the multiple asset terminals, and one or more groups are formed based on the relative positions.

15. setting one of the plurality of slave asset terminals as a master asset terminal based on at least one of a GPS communication quality, a UWB communication quality, and a battery level; 13. The method of claim 12, further comprising the step of: configuring an existing master asset terminal as a slave asset terminal.

16. In the step of generating the reference position, Extracting a midpoint between two slave asset terminals located at opposite points with respect to the master asset terminal, and generating a center point of a figure connecting the extracted midpoints as the reference position; The asset tracking method of claim 12, wherein one of the following points is extracted as the midpoint: a half-way point of a straight line connecting the asset positions of two slave asset terminals located at opposite points based on the master asset terminal, and a half-way point of a straight line connecting positions moved a distance of the relative position from the asset positions of two slave asset terminals located at opposite points based on the master asset terminal in the direction of the relative position.

17. In the step of generating the corrected asset location, The asset tracking method according to claim 12, further comprising generating a corrected asset position of the slave asset terminal by moving a distance of the relative position from the reference point in a direction of the relative position using the reference position as a reference point.

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