System, central unit and methods for positioning calibration

Abstract

A system configured to calibrate a position of a moving object in an underground environment is provided. The system comprises the moving object operating in the underground environment, at least one static transmitter located in the underground environment and a central unit. The central unit is configured to track a position of the moving object. It is detected that the moving object is located in proximity of a first static transmitter of the at least one static transmitter. The central unit receives a first message adapted to indicate a detection of the moving object being located in proximity to the first static transmitter. A position of the moving object is obtained. The position of the moving object is calibrated based on the obtained position of the moving object and the position of the first static transmitter.

Description

[0001] SYSTEM, CENTRAL UNIT AND METHODS FOR POSITIONING CALIBRATION

[0002] TECHNICAL FIELD

[0003] Embodiments herein relate to a system, method, and a central unit for calibrating a position of a moving object in an underground and / or delimited environment.

[0004] BACKGROUND

[0005] In mining and tunneling, there is a constant ongoing process of improving efficiency, productivity, and safety. Examples of changes and / or improvements that are carried out with an increasing extent, especially in mining, is the automation, fully or partly, of various processes occurring in mining. Methods for localization, mapping, control, and motion planning have enabled development and deployment of fully or partly autonomous vehicles and / or mobile machines, hereinafter denoted as vehicle.

[0006] When working in underground environments, it is often important to gather knowledge about where various objects are located. The underground environments may in many cases have a significant extent and be difficult to overview. Collecting information about positions may therefore be partly problematic. Direct visual observation is made difficult by intervening rock, but also by the fact that it is dark. Other methods are therefore used.

[0007] One possible way of determining position is to put a transmitter on an object and by triangulation or trilateration determine its position in relation to a communication network.

[0008] In underground environments, these communication networks are often already established to allow the mine's units to communicate with each other. However, the communication over these networks is beset with certain concerns that affect the network's performance, for example the corridors are narrow, curved, and sometimes filled with larger machines. This means that the coverage and accuracy quite often leave something to be desired. If a mining machine passes, the signal will be significantly affected, with this a position that is calculated based on this signal will also be affected. Then the environment is continuously changed by explosions, vibrations and also by the fact that the digging itself leads to the expansion of the mine. This contributes to a high degree of uncertainty in automatic position determinations. In many situations, it is only possible to determine which access point is closest, but higher accuracy than that is difficult to achieve. As a result, existing methods such as triangulation or trilateration are in reality difficult to apply in an underground environment.

[0009] Due to the use of autonomous machines and general production planning, it is important to accurately locate assets.

[0010] The above issues may result in an unreliable localization of an object used in underground mining.

[0011] SUMMARY

[0012] As part of developing embodiments herein a problem has been identified and will first be discussed.

[0013] A problem in underground, or delimited, environments, is keeping track of the location of objects moving in said underground environment. This due to e.g., the lack of satellite coverage when using a satellite based positioning system, tunnels limiting the coverage of wireless communications networks used to for positioning, or machines block signals to access points to said wireless communications network. A lack of accurate positioning information of moving objects in the underground environment may impact the operational efficiency by limiting production planning. Le., the production plans must take into account the limited positioning accuracy which may result in decreased efficiency. Furthermore, a lack of accurate positioning information may impact the safety in the underground environment.

[0014] An object of embodiments herein is to provide a mechanism that increases operational safety of moving objects and improves the operational efficiency and productivity in a delimited environment, such as an underground environment. The object is achieved by the independent claims.

[0015] According to a first aspect, a method for calibrating a position of a moving object in an underground environment is provided. The underground environment comprises the moving object, at least one static transmitter and a central unit. The central unit is tracking a position of the moving object.

[0016] It is detected that the moving object is located in proximity of a first static transmitter of the at least one static transmitter.

[0017] The central unit receives a first message indicating a detection of the moving object being located in proximity to the first static transmitter. A position of the moving object is obtained.

[0018] The position of the moving object is calibrated based on the obtained position of the moving object and a position of the first static transmitter.

[0019] By calibrating the position of the moving object, the operational efficiency, safety and productivity may be increased. This is enabled by the more accurate positioning resulting from the calibration may allow planning a more efficient production taking the accurate location of moving objects into account.

[0020] According to an exemplary embodiment, the received first message may further comprise a first time stamp associated to the detection. The obtained position may be associated to a second time stamp.

[0021] According to an exemplary embodiment, obtaining the position of the moving object may comprise obtaining a position which associated second time stamp is within the first threshold of the first time stamp. By obtaining a position which associated second time stamp is within the first threshold of the first time stamp, a recent position of the moving object may be obtained. This is enabled by the fact that a position which associated second time stamp is not within the first threshold of the first stamp is not obtained, i.e. , older positions are filtered out.

[0022] According to an exemplary embodiment, calibrating the position of the moving object may comprise comparing the obtained position of the moving object and the position of the first static transmitter. Thus, possible errors associated with the obtained position may be detected. This is enabled by the fact that the position of the first static transmitter is fixed, i.e., the first static transmitter is stationary.

[0023] According to an exemplary embodiment, calibrating the position of the moving object may comprise updating the obtained position of the moving object when the difference between the obtained position and the positioned of the first static transmitter exceeds a second threshold. By this, a more accurate positioning of the moving object is achieved. This is enabled by reducing the positioning error, which is achieved when updating the obtained position when difference between the obtained position and the position of the first static transmitter exceeds the second threshold.

[0024] According to an exemplary embodiment, the obtained position of the moving object may be updated by replacing the obtained position with the position of the first static transmitter. By replacing the obtained position with the position of the first static transmitter, a more accurate positioning of the moving object is achieved. This is enabled by the fact that the position of the first static transmitter is fixed and known, and thus the replacement results in a reduced positioning error of the moving object. According to an exemplary embodiment, obtaining the position of the moving object may comprise any one out of:

[0025] Receiving the position from the moving object in the first message, receiving the position from the moving object in a second message, or obtaining the position from positioning data stored in the central unit.

[0026] According to an exemplary embodiment, the first message may further comprise an identity of the first static transmitter. The central unit may obtain the position of the first static transmitter using the identity of the first static transmitter.

[0027] By this, the position of the first static transmitter may be efficiently obtained. The identity of the first static transmitter may be used by the central unit to obtain the position of the first static transmitter e.g., by searching a memory or database where positions of static transmitters are stored.

[0028] According to an exemplary embodiment, the detecting may comprise the moving object detecting the first static transmitter. The central unit may receive the first message from the moving object.

[0029] According to an exemplary embodiment, the detecting may comprise the first static transmitter detecting the moving object. The central unit may receive the first message from the first static transmitter.

[0030] According to a second aspect, a method performed by a central unit for calibrating a position of a moving object in an underground environment is provided. The underground environment comprises the moving object and at least one static transmitter. The central unit is tracking a position of the moving object

[0031] The central unit receives a first message indicating a detection of the moving object being located in proximity to the first static transmitter.

[0032] The central unit obtains a position of the moving object.

[0033] The central unit calibrates the position of the moving object based on the obtained position of the moving object and a position of the first static transmitter.

[0034] By calibrating the position of the moving object, the operational efficiency and productivity may be increased. This since the more accurate positioning resulting from the calibration may allow planning a more efficient production taking the more accurate location of moving objects into account.

[0035] According to an exemplary embodiment, the received first message may further comprise a first time stamp associated to the detection. The obtained position may be associated to a second time stamp. According to an exemplary embodiment, obtaining the position of the moving object may comprise obtaining a position which associated second time stamp is within the first threshold of the first time stamp. By obtaining a position which associated second time stamp is within the first threshold of the first time stamp, a recent position of the moving object may be obtained. This is enabled by the fact that a position which associated second time stamp is not within the first threshold of the first stamp is not obtained, i.e. , older positions are filtered out.

[0036] According to an exemplary embodiment, calibrating the position of the moving object may comprise comparing the obtained position of the moving object and the position of the first static transmitter. Thus, possible errors associated with the obtained position may be detected. This is enabled by the fact that the position of the first static transmitter is fixed, i.e., the first static transmitter is stationary.

[0037] According to an exemplary embodiment, calibrating the position of the moving object may comprise updating the obtained position of the moving object when the difference between the obtained position and the positioned of the first static transmitter exceeds a second threshold. By this, a more accurate positioning of the moving object is achieved. This is enabled by reducing the positioning error, which is achieved when updating the obtained position when difference between the obtained position and the position of the first static transmitter exceeds the second threshold.

[0038] According to an exemplary embodiment, the obtained position of the moving object may be updated by replacing the obtained position with the position of the first static transmitter. By replacing the obtained position with the position of the first static transmitter, a more accurate positioning of the moving object is achieved. This is enabled by the fact that the position of the first static transmitter is fixed and known, and thus the replacement results in a reduced positioning error of the moving object.

[0039] According to an exemplary embodiment, obtaining the position of the moving object may comprise any one out of:

[0040] Receiving the position from the moving object in the first message, receiving the position from the moving object in a second message, or obtaining the position from positioning data stored in the central unit.

[0041] According to an exemplary embodiment, the first message may further comprise an identity of the first static transmitter. The central unit may obtain the position of the first static transmitter using the identity of the first static transmitter. By this, the position of the first static transmitter may be efficiently obtained. According to an exemplary embodiment, receiving the first message may comprise receiving the first message from any one out of:

[0042] The moving object, or the first static transmitter.

[0043] According to a third aspect, a system configured to calibrate a position of a moving object in an underground environment is provided. The system comprises the moving object operating in the underground environment, at least one static transmitter located in the underground environment and a central unit. The central unit is configured to track a position of the moving object.

[0044] It is detected that the moving object is located in proximity of a first static transmitter of the at least one static transmitter.

[0045] The central unit receives a first message adapted to indicate a detection of the moving object being located in proximity to the first static transmitter.

[0046] Obtain a position of the moving object.

[0047] Calibrate the position of the moving object based on the obtained position of the moving object and the position of the first static transmitter.

[0048] By calibrating the position of the moving object, the operational efficiency, safety and productivity may be increased. This since the more accurate positioning resulting from the calibration may allow planning a more efficient production taking the accurate location of moving objects into account.

[0049] According to a fourth aspect, a central unit configured to calibrate a position of a moving object in an underground environment. The underground environment comprising the moving object and at least one static transmitter. The central unit is configured to track a position of the moving object.

[0050] The central unit receives a first message adapted to indicate a detection of the moving object being located in proximity to the first static transmitter.

[0051] The central unit obtains a position of the moving object.

[0052] The central unit calibrates the position of the moving object based on the obtained position of the moving object and a position of the first static transmitter.

[0053] By calibrating the position of the moving object, the operational efficiency, safety and productivity may be increased. This is enabled by the more accurate positioning resulting from the calibration which may allow planning a more efficient production taking the accurate location of moving objects into account. BRIEF DESCRIPTIONS OF DRAWINGS

[0054] Examples of embodiments herein are described in more detail with reference to attached drawings in which:

[0055] Fig. 1 shows an example of system according to embodiments herein.

[0056] Fig. 2 shows an example of an underground environment according to embodiments herein.

[0057] Fig. 3 shows a flowchart depicting a method according to embodiments herein.

[0058] Fig. 4 shows a flowchart depicting a method according to embodiments herein.

[0059] Figs. 5a-b shows examples according to embodiments herein.

[0060] Figs. 6a-b shows schematic block diagrams illustrating embodiments of a central unit.

[0061] DETAILED DESCRIPTION

[0062] An object of embodiments herein is to provide mechanisms that increase the operational efficiency and productivity in a delimited environment, such as an underground environment, of an object operating in a delimited, such as an underground environment.

[0063] Embodiments herein may bring the advantage of an increased operational safety in an underground environment. This may be achieved by, as mentioned above, making it possible to accurately locate objects moving in the underground environment. Further, embodiments herein may bring the advantage of an improved operational efficiency in the underground environment. This by enabling planning a more efficient production taking the accurate location of moving objects into account.

[0064] Fig. 1 shows a schematic illustration of a system 105 comprising a first static transmitter 120 and a moving object 110. The moving object may e.g., be a vehicle, a machine and / or a mobile device. A machine and / or vehicle may e.g., be an autonomous machine and / or vehicle, a remote-controlled machine and / or vehicle, or an operator controlled machine and / or vehicle A mobile device may e.g., comprise, but is not limited to, a mobile phone, a tablet, a laptop, a wearable device, a sensor and / or any other type of mobile device. The mobile device may e.g., be worn or carried by an operator in the underground environment, or it may be a mobile device that is located in a vehicle and / or machine. The first static transmitter 120 may e.g., be an access point, and RFID tag, and / or a wireless short range transmitter. The system may further comprise a central unit 130. Methods according to embodiments herein may be performed by the system 105, and / or the central unit 130. These nodes may be Distributed Nodes (DN)s and functionality, e.g. comprised in a cloud may be used for performing or partly performing the methods.

[0065] In order to efficiently keep track of moving objects, such as the moving object 110, in the underground environment 100, the central unit 130 may e.g., receive location updates from the moving object 110. Alternatively, or additionally, the central unit 130 may estimate the location of the moving object 110 e.g., based on a mission or operation performed by the moving object 110 and / or a previous known location of the moving object 110. However, this has certain drawbacks. E.g., the moving object 110 may be unable to transmit a location update e.g., due to lack of network coverage, or the location received from the moving object 110 may lack accuracy. Further, a location estimate performed by the central unit 130 is only an estimate, and may thereby also lack accuracy.

[0066] Fig. 2 shows a schematic illustration of an underground environment 100 according to embodiments herein. One or more moving objects 110 may operate in the underground environment 100. Fig. 1a further shows a first static transmitter 120 arranged in the underground environment 100. The first static transmitter 120 may be arranged for detecting a moving object passing by. Alternatively, the moving object 110 detects that it is passing by the first static transmitter 120. In other words, it is detected, by either the first static transmitter 120 or the moving object 110, that the moving object 110 is located in proximity to the first static transmitter 120.

[0067] In order to efficiently keep track of the location of moving objects, such as the moving object 110, the central unit 130 may receive a message whenever it is detected that the moving object 110 is in proximity to a static transmitter, such as the first static transmitter 120. In response to, or in conjunction with, receiving the message, the central unit 130 may obtain a position of the moving object 110. This obtained position may be received from moving object 110 or it may a previously known position of the moving object 110 stored e.g., in a memory of the central unit 130 or in a database accessible to the central unit 130. The central unit 130 may then calibrate the position of the moving object 110 based on the obtain position and a position of the static transmitter 120. This allows the central unit 130 obtain an accurate position of the moving object 110 since the position of the first static transmitter 130 is known and fixed.

[0068] As mentioned above, embodiments herein bring the advantage of an increased operational safety an underground environment. This may result in increased operational efficiency and also an increased productivity in the underground environment, since e.g., an accurate location of moving objects is known and may be utilized to efficiently plan productions, mission, operation and routes in the underground environment.

[0069] Fig. 3 shows an example embodiment of a method for calibrating a position of the moving object 110 in the underground environment 100. The underground environment 100 comprises the moving object 110 and at least one static transmitter 120. A central unit (130) is tracking a position of the moving object 110. The method may be performed by the system 105. The actions may be performed by the central unit 130, the moving object 110 and / or the first static transmitter 120 comprised in the system 105 in any suitable combination.

[0070] The method comprises the following actions, which may be taken in any suitable order. Optional actions are referred to as dashed boxes in Fig. 3.

[0071] Action 301

[0072] It is detected that the moving object 110 is located in proximity of a first static transmitter 120 of the at least one static transmitter 120. As explained below, by detecting that the moving object 110 is in proximity of the first static transmitter 120, is possible to deduce a location of the moving object 110. This since the location of the first static transmitter 120 is known.

[0073] In some embodiments, the moving object 110 detects the first static transmitter 120. Thus, the moving object 110 detects that it located in proximity of the first static transmitter 120 by detecting the first static transmitter 120. The at least one static transmitter 120, such as the first static transmitter 120, may transmit a signal, e.g., a beacon and / or discovery signal. The moving object 110 may detect the first static transmitter 120 by receiving, such as detecting, the transmitted signal. The transmitted signal may be broadcasted by the first static transmitter 120.

[0074] In some embodiments, the first static transmitter 120 detects the moving object 110. Thus, the first static transmitter 120 detects that the moving object 110 is located in proximity of the first static transmitter 120 by detecting the moving object 110. In such an example, the first static transmitter 120 may also be referred to as the first static transceiver 120, configured to be able to transmit and receive signals and / or messages. The moving object 110 may transmit a signal, e.g., a beacon and / or discovery signal. The first static transmitter, or transceiver, 120 detect the moving object 110 by receiving, such as detecting, the transmitted signal. The transmitted signal may be broadcasted by the moving object 110. The first message may further comprise an identity of the moving object 110.

[0075] Action 302

[0076] The central unit 130 receives a first message indicating the detection of the moving object 130 being located in proximity to the first static transmitter 120. By this, the central unit 130 may, as explained below, calibrate a previously known position of the moving object 110.

[0077] In some embodiments, the received first message may further comprise a first time stamp associated to the detection. The first time stamp associated to the detection may e.g., indicate the time of the detection, i.e., the time it was detected the moving objected was located in proximity to the first static transmitter 120.

[0078] In some embodiments, the central unit 130 may receive the first message from the moving object 110. This may e.g., happen when the moving object 110 detects that it is in proximity of the first static transmitter 120, as explained above. Thus, the moving object 110 may transmit the first message to the central unit 130 after said detection.

[0079] In some embodiments, central unit 130 may receive the first message from the first static transmitter 120. This may e.g., happen when the first static transmitter 120 detects that the moving object 110 is in proximity of the first static transmitter 120, as explained above. Thus, the first static transmitter 120 may transmit the first message to the central unit 130 after said detection.

[0080] In some embodiments, the first message may further comprise an identity of the first static transmitter 120. The central unit 130 may obtain the position of the first static transmitter 120 using the identity of the first static transmitter 120. The central unit 130 may query a database to obtain the position of the first static transmitter 120, e.g., by providing the identity of the first static transmitter 120 as input to the database and obtaining, such as receiving, the position as an output from the database. The database may be comprised in the central unit 130, or may alternatively be a standalone database or part of another entity. The first message may in some examples further comprise an identity of the moving object 110.

[0081] Action 303

[0082] A position of the moving object 110 is obtained. The position of the moving object 110 may e.g., be obtained by the central unit 130.

[0083] The position of the moving object moving object 110 may obtained in different ways. E.g., obtaining the position of the moving object 110 may comprise any one out of:

[0084] - Receiving the position from the moving object 110 in the first message,

[0085] - receiving the position from the moving object 110 in a second message, or

[0086] - obtaining the position from positioning data stored in the central unit 130, e.g., in a database and / or a memory.

[0087] As a further example, the position of the moving object may be obtained, e.g., by the central unit 130, from a database. The database may be a standalone database or part of another entity. The database may be the same database from which the position of the first static transmitter is obtained, or it may be another database. To obtain the position from the data base and / or memory, may comprise querying the database and / or memory, e.g., by providing the identity of the moving object 110 as input to the database and / or memory and obtaining, such as receiving, the position as an output from the database and / or memory.

[0088] When receiving the position of the moving object 110 in the first message or the second message, the position may be a position calculated and / or estimated by the moving object 110. The second message may e.g., be received in conjunction with the first message.

[0089] In some embodiments, the obtained position may be associated to a second time stamp. The second time stamp may e.g., the time the position was calculated and / or estimated.

[0090] In some embodiments, e.g., when obtaining the position of the moving object 110 from a database and / or memory, obtaining the position of the moving object 110 may comprise obtaining a position which associated second time stamp is within the first threshold of the first time stamp. E.g., the database and / or memory may have more than one stored position of the moving object 110, each stored position associated with a respective second time stamp. When obtaining the position of the moving object 110, the stored position with an associated stamp that is within the first threshold of the first time stamp may be obtained. That is, the second time stamp may be compared with the first stamp in order to determine if the second time stamp is within the first threshold.

[0091] Alternatively, or additionally, obtaining the position of the moving object 110 may comprise a position among the more than one stored positions which associated second time stamp is closest in time to the first time stamp.

[0092] Action 304

[0093] The position of the moving object 110 is calibrated based on the obtained position of the moving object 110 and a position of the first static transmitter 120. By calibrating the position of the moving object 110, a more accurate positioning of the moving object 110 may be achieved.

[0094] In some embodiments, calibrating the position of the moving object 110 comprises comparing the obtained position of the moving object 110 and the position of the first static transmitter 120. In other words, the position of the moving object 110 is compared to the position of the first static transmitter 120. This way, a difference between the obtained position of the moving object 110 and the position of the first static transmitter 120 is obtained. This difference may e.g., be used to determine how accurate the obtained position of the moving object 110 is.

[0095] In some embodiments, calibrating the position of the moving object 110 may comprise updating the obtained position of the moving object 110 when the difference between the obtained position of the moving object 110 and the positioned of the first static transmitter 120 exceeds a second threshold. Thus, the position of the moving object 110 may be calibrated when the difference between the two positions, i.e., the position of the moving object 110 and the position of the first static transmitter 120, is exceeds the second threshold. As mentioned above, a difference between the obtained position of the moving object 110 and the position of the first static transmitter 120 is obtained by comparing the two positions.

[0096] The obtained position of the moving object 110 may e.g., be updated by replacing the obtained position with the position of the first static transmitter 120. This way, the positioning accuracy of the moving object is increased. This since the position of the first static transmitter is known and doesn’t change.

[0097] Fig. 4 shows an example embodiment of a method performed by the central unit 130 for calibrating a position of the moving object 110 in the underground environment 100. The underground environment 100 comprises the moving object 110 and at least one static transmitter 120. The central unit 130 is tracking a position of the moving object 110. The method comprises the following actions, which may be taken in any suitable order. Optional actions are referred to as dashed boxes in Fig. 4.

[0098] Action 401

[0099] The central unit 130 receives a first message indicating the detection of the moving object 130 being located in proximity to the first static transmitter 120. By this, the central unit 130 may, as explained below, calibrate a previously known position of the moving object 110.

[0100] In some embodiments, the received first message may further comprise a first time stamp associated to the detection. The first time stamp associated to the detection may e.g., indicate the time of the detection, i.e., the time it was detected the moving objected was located in proximity to the first static transmitter 120.

[0101] In some embodiments, the central unit 130 may receive the first message from the moving object 110. This may e.g., happen when the moving object 110 detects that it is in proximity of the first static transmitter 120, as explained above. Thus, the moving object 110 may transmit the first message to the central unit 130 after said detection.

[0102] In some embodiments, central unit 130 may receive the first message from the first static transmitter 120. This may e.g., happen when the first static transmitter 120 detects that the moving object 110 is in proximity of the first static transmitter 120, as explained above. Thus, the first static transmitter 120 may transmit the first message to the central unit 130 after said detection.

[0103] In some embodiments, the first message may further comprise an identity of the first static transmitter 120. The central unit 130 may obtain the position of the first static transmitter 120 using the identity of the first static transmitter 120. The central unit 130 may query a database to obtain the position of the first static transmitter 120, e.g., by providing the identity of the first static transmitter 120 as input to the database and obtaining, such as receiving, the position as an output from the database. The database may be comprised in the central unit 130, or may alternatively be a standalone database or part of another entity. The first message may in some examples further comprise an identity of the moving object 110. The first message may further comprise an identity of the moving object 110.

[0104] Action 402 The central unit 130 obtains a position of the moving object 110. The position of the moving object moving object 110 may obtained in different ways. E.g., obtaining the position of the moving object 110 may comprise any one out of:

[0105] - Receiving the position from the moving object 110 in the first message,

[0106] - receiving the position from the moving object 110 in a second message, or

[0107] - obtaining the position from positioning data stored in the central unit 130, e.g., in a database and / or a memory.

[0108] As a further example, the position of the moving object may be obtained by the central unit 130 from a database. The database may be a standalone database or part of another entity. The database may be the same database from which the position of the first static transmitter is obtained, or it may be another database. Obtaining the position from the database and / or memory, may comprise querying the database and / or memory, e.g., by providing the identity of the moving object 110 as input to the database and / or memory and obtaining, such as receiving, the position as an output from the database and / or memory.

[0109] When receiving the position of the moving object 110 in the first message or the second message, the position may be a position calculated and / or estimated by the moving object 110. The second message may e.g., be received in conjunction with the first message.

[0110] In some embodiments, the obtained position may be associated to a second time stamp. The second time stamp may e.g., the time the position was calculated and / or estimated.

[0111] In some embodiments, e.g., when obtaining the position of the moving object 110 from a database and / or memory, obtaining the position of the moving object 110 may comprise obtaining a position which associated second time stamp is within the first threshold of the first time stamp. E.g., the database and / or memory may have more than one stored position of the moving object 110, each stored position associated with a respective second time stamp. When obtaining the position of the moving object 110, the stored position with an associated stamp that is within the first threshold of the first time stamp may be obtained. That is, the second time stamp may be compared with the first stamp in order to determine if the second time stamp is within the first threshold.

[0112] Alternatively, or additionally, obtaining the position of the moving object 110 may comprise obtaining a position among the more than one stored positions which associated second time stamp is closest in time to the first time stamp compared with each of the second time stamps. Action 403

[0113] The central unit 130 calibrates the position of the moving object 110 based on the obtained position of the moving object 110 and a position of the first static transmitter 120. By calibrating the position of the moving object 110, a more accurate positioning of the moving object 110 may be achieved.

[0114] In some embodiments, calibrating the position of the moving object 110 comprises comparing the obtained position of the moving object 110 and the position of the first static transmitter 120. In other words, the position of the moving object 110 is compared to the position of the first static transmitter 120. This way, a difference between the obtained position of the moving object 110 and the position of the first static transmitter 120 is obtained. This difference may e.g., be used to determine how accurate the obtained position of the moving object 110 is.

[0115] In some embodiments, calibrating the position of the moving object 110 may comprise updating the obtained position of the moving object 110 when the difference between the obtained position of the moving object 110 and the positioned of the first static transmitter 120 exceeds a second threshold. Thus, the position of the moving object 110 may be calibrated when the difference between the two positions, i.e., the position of the moving object 110 and the position of the first static transmitter 120, is exceeds the second threshold. As mentioned above, a difference between the obtained position of the moving object 110 and the position of the first static transmitter 120 may be obtained by comparing the two positions.

[0116] The obtained position of the moving object 110 may e.g., be updated by replacing the obtained position with the position of the first static transmitter 120. This way, the positioning accuracy of the moving object is increased. This is since the position of the first static transmitter is known and doesn’t change.

[0117] Figs. 5a-b depict examples of signaling diagrams according to embodiments herein. The signaling diagrams also reflect actions corresponding to those disclosed in the detailed description of Figs. 3 and 4. Optional actions are referred to as dashed boxes and / or lines in Fig. 5a-c. As mentioned above the method described in relation to Figs. 3 and 4 may be performed by the system 105, and the actions may be performed by the moving object 110, the first static transmitter 120 and / or the central unit 130 comprised in the system 105 in any suitable combination. Fig. 5a-c describes examples of embodiments where different combinations of the central unit 130 the moving object 110 and / or first static transmitter 120 performs the method above.

[0118] Fig. 5a exemplifies embodiments where the system 105 calibrates the position of the moving object 110. In this example, the system 105 comprises the moving object 110, the central unit 130 and the first static transmitter 120. The example comprises the following actions, which may be taken in any suitable order.

[0119] S51a. The moving object 110 detects that it is located in proximity to the first static transmitter 130, e.g., in accordance with action 301 above.

[0120] S52a. The central unit 130 receives the first message from the moving object 110, e.g., in accordance with any of Actions 302 and 401 above. The first message indicates that the moving object 110 is located in proximity to the first static transmitter 120.

[0121] S53a. The central unit 130 obtains a position of the moving object 110, e.g., in accordance with any of Actions 303 and 402 above. As mentioned above, the position may be obtained from the moving object 110 or from memory or database.

[0122] S54a. The central unit 130 calibrates the position of the moving object 110 based on the obtained position and the position of the first static transmitter 120, e.g., in accordance with any of Actions 304 and 403 above.

[0123] Fig. 5b exemplifies embodiments where the system 105 calibrates the position of the moving object 110. In this example, the system 105 comprises the moving object 110, the central unit 130 and the first static transmitter 120. The example comprises the following actions, which may be taken in any suitable order.

[0124] S51 b. The first static transmitter 120 detects that the moving object 110 is located in the proximity of the first static transmitter 120, e.g., in accordance with action 301 above.

[0125] S52b. The central unit 130 receives the first message from the first static transmitter 120, e.g., in accordance with any of Actions 302 and 401 above. The first message indicates that the moving object 110 is located in proximity to the first static transmitter 120.

[0126] S53b. The central unit 130 obtains a position of the moving object 110, e.g., in accordance with any of Actions 303 and 402 above. The position of the moving object is obtained from a memory or a database. S54b. The central unit 130 calibrates the position of the moving object 110 based on the obtained position and the position of the first static transmitter 120, e.g., in accordance with any of Actions 304 and 403 above.

[0127] Fig. 6a disclose an example configuration of the central unit 130 configured to calibrate a position of a moving object 110 in the underground environment 100. The central unit 130 comprises a memory 660 operable to store instructions and processing circuitry 660 operable to execute the instructions.

[0128] The central unit 130 may comprise an input and output interface 600 configured to communicate with, e.g., moving objects such as the moving object 110, static transmitters such as the first static transmitter 120, other stat and / or databases.

[0129] Fig. 6b also discloses an example configuration of processing circuitry for a central unit, e.g., the processing circuitry 650 disclosed in Fig. 6a. The processing circuitry may comprise a receiving unit 610, an obtaining unit 620 and a calibrating unit 630 configured to perform the methods above.

[0130] The embodiments herein may be implemented through the processing circuitry 650 in the central unit 130 depicted in Figure 6a, together with respective computer program code for performing the functions and actions of the embodiments herein. The processing circuitry 650 may comprise one or more processors and one or more memory units. The memory units may be the memory 660. The program code mentioned above may also be provided as a computer program product, for instance in the form of a data carrier carrying computer program code for performing the embodiments herein when being loaded into the central unit 130. One such carrier may be in the form of a CD ROM disc, a USB flash drive, and / or an Over-the-Air (OTA) carrier. It is however feasible with other data carriers such as a memory stick. The computer program code may furthermore be provided as pure program code on a server and downloaded to the central unit 130.

[0131] The memory 660 of the central unit 130 may further comprise one or more memory units. The memory 660 is configured to store instructions executable by the processing circuitry 650. The memory 660 is arranged to be used to store e.g. information, messages, indications, configurations, locations, positions, time stamps, identities, measurements and applications to perform the methods herein when being executed in executed in the central unit 130. The central unit 130 and / or the processing circuitry 650 is configured to calibrate a position of the moving object 110 in the underground environment 100. The underground environment 100 comprises the moving object 110 and at least one static transmitter 120. The central unit 130 is configured to track a position of the moving object 110.

[0132] The central unit 130 and / or the processing circuitry 650 receives a first message adapted to indicate a detection of the moving object 130 being located in proximity to the first static transmitter 120.

[0133] The central unit 130 and / or the processing circuitry 650 obtains a position of the moving object 110.

[0134] The central unit 130 and / or the processing circuitry 650 calibrates the position of the moving object 110 based on the obtained position of the moving object 110 and a position of the first static transmitter 120.

[0135] In some embodiments, a computer program 670 comprises instructions, which when executed by the processing circuitry 650, e.g., of the respective at least one processor of the processing circuitry 650, cause the processing circuitry 650 of the central unit 130 to perform the actions above.

[0136] In some embodiments, a respective carrier 680 comprises the respective computer program 670, wherein the carrier 680 is one of an electronic signal, an optical signal, an electromagnetic signal, a magnetic signal, an electric signal, a radio signal, a microwave signal, or a computer-readable storage medium.

[0137] Those skilled in the art will appreciate that the units in the central unit 130 described above may refer to a combination of analogue and digital circuits, and / or one or more processors configured with software and / or firmware, e.g., stored in the central unit 130, that when executed by the respective one or more processors such as the processors described above. One or more of these processors, as well as the other digital hardware, may be included in a single Application-Specific Integrated Circuitry (ASIC), or several processors and various digital hardware may be distributed among several separate components, whether individually packaged or assembled into a system-on-a- chip (SoC).

[0138] It will be appreciated that the foregoing description and the accompanying drawings represent non-limiting examples of the methods and apparatus taught herein. As such, the apparatus and techniques taught herein are not limited by the foregoing description and accompanying drawings. Instead, the embodiments herein are limited only by the following claims and their legal equivalents.

Claims

CLAIMS1. A method for calibrating a position of a moving object (110) in an underground environment (100), the underground environment (100) comprising the moving object (110), at least one static transmitter (120) and a central unit (130), wherein the central unit (130) is tracking a position of the moving object (110), the method comprising: detecting (301 ) that the moving object (110) is located in proximity of a first static transmitter (120) of the at least one static transmitter (120), receiving (302), by the central unit (130), a first message indicating a detection of the moving object (130) being located in proximity to the first static transmitter (120), obtaining (303) a position of the moving object (110), calibrating (304) the position of the moving object (110) based on the obtained position of the moving object (110) and a position of the first static transmitter (120).

2. The method according to claim 1 , wherein the received (302) first message further comprises a first time stamp associated to the detection (301), and wherein the obtained (303) position is associated to a second time stamp.

3. The method according to claim 2, wherein obtaining (303) the position of the moving object (110) comprises obtaining a position which associated second time stamp is within the first threshold of the first time stamp.

4. The method according to any of claims 1-3, wherein calibrating (304) the position of the moving object (110) comprises comparing the obtained position of the moving object (110) and the position of the first static transmitter (120).

5. The method according to any of claims 1-4, wherein calibrating (304) the position of the moving object (110) comprises updating the obtained position of the moving object (110) when the difference between the obtained position and the positioned of the first static transmitter (120) exceeds a second threshold.

6. The method according to claim 5, wherein the obtained position of the moving object (110) is updated by replacing the obtained position with the position of the first static transmitter (120).

7. The method according to any of claims 1-6, wherein obtaining (303) the position of the moving object (110) comprises any one out of:- receiving the position from the moving object (110) in the first message,- receiving the position from the moving object (110) in a second message, or- obtaining the position from positioning data stored in the central unit (130).

8. The method according to any of claims 1-7, wherein the first message further comprises an identity of the first static transmitter (120), and wherein the central unit (130) obtains the position of the first static transmitter (120) using the identity of the first static transmitter (120).

9. The method according to any of claims 1-8, wherein the detecting (301) comprises the moving object (110) detecting the first static transmitter (120), and wherein the central unit (130) receives (302) the first message from the moving object (110).

10. The method according to any of claims 1-8, wherein the detecting (301) comprises the first static transmitter (120) detecting the moving object (110), and wherein the central unit (130) receives (302) the first message from the first static transmitter (120).

11. A method performed by a central unit (130) for calibrating a position of a moving object (110) in an underground environment (100), the underground environment (100) comprising the moving object (110) and at least one static transmitter (120), wherein the central unit (130) is tracking a position of the moving object (110), the method comprising: receiving (401) a first message indicating a detection of the moving object (130) being located in proximity to the first static transmitter (120), obtaining (402) a position of the moving object (110), calibrating (403) the position of the moving object (110) based on the obtained position of the moving object (110) and a position of the first static transmitter (120).

12. The method according to claim 11, wherein the received (401) first message further comprises a first time stamp associated to the detection, and wherein the obtained (402) position is associated to a second time stamp.

13. The method according to any of claims 12, wherein obtaining (402) the position of the moving object (110) comprises obtaining a position which associated second time stamp is within the first threshold of the first time stamp.

14. The method according to any of claims 11-13, wherein calibrating (403) the position of the moving object (110) comprises comparing the obtained position of the moving object (110) and the position of the first static transmitter (120).

15. The method according to any of claims 11-14, wherein calibrating (403) the position of the moving object (110) comprises updating the obtained position of the moving object (110) when the difference between the obtained position and the positioned of the first static transmitter (120) exceeds a second threshold.

16. The method according to claim 15, wherein the obtained position of the moving object (110) is updated by replacing the obtained position with the position of the first static transmitter (120).

17. The method according to any of claims 11-16, wherein obtaining (402) the position of the moving object (110) comprises any one out of:- receiving the position from the moving object (110) in the first message,- receiving the position from the moving object (110) in a second message, or- obtaining the position from positioning data stored in the central unit (130).

18. The method according to any of claims 11-17, wherein the first message further comprises an identity of the first static transmitter (120), and wherein the central unit (130) obtains the position of the first static transmitter (120) using the identity of the first static transmitter (120).

19. The method according to any of claims 11-18, wherein receiving (401) the first message comprises receiving the first message from any one out of:- the moving object (110), or- the first static transmitter (120).

20. A computer program 670 comprising instructions, which when executed by a processing circuitry 650, causes the processing circuitry 650 to perform actions according to any of the embodiments 11-19.

21. A system (105) configured to calibrate a position of a moving object (110) in an underground environment (100), the system comprising the moving object (110) operating in the underground environment (100), at least one static transmitter (120) located in the underground environment (100) and a central unit (130), wherein the central unit (130) is configured to track a position of the moving object (110), the system (105) further being configured to: detect that the moving object (110) is located in proximity of a first static transmitter (120) of the at least one static transmitter (120), receive, by the central unit (130), a first message adapted to indicate a detection of the moving object (130) being located in proximity to the first static transmitter (120), obtain a position of the moving object (110), and calibrate the position of the moving object based on the obtained position of the moving object (110) and the position of the first static transmitter (120).

22. The system (105) according to claim 21, wherein the system (1) is further configured to perform the method according to any of claims 2-10.

23. A central unit (130) configured to calibrate a position of a moving object (110) in an underground environment (100), the underground environment (100) comprising the moving object (110) and at least one static transmitter (120), wherein the central unit (130) is configured to track a position of the moving object (110), the central unit (130) further being configured to: receive a first message adapted to indicate a detection of the moving object (130) being located in proximity to the first static transmitter (120), obtain a position of the moving object (110), calibrate the position of the moving object (110) based on the obtained position of the moving object (110) and a position of the first static transmitter (120).

24. The central unit (130) according to claim 23, wherein the central unit (130) is further configured to perform the method according to any of claims 11-19.

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