EP4627422A1

EP4627422A1 - Traffic control methods and systems for determining a safe performance of a specific task within a safety area in an underground environment

Info

Publication number: EP4627422A1
Application number: EP22817424.9A
Authority: EP
Inventors: Richard Hendeberg; Andreas ÖKVIST
Original assignee: Epiroc Rock Drills AB
Current assignee: Epiroc Rock Drills AB
Priority date: 2022-11-30
Filing date: 2022-11-30
Publication date: 2025-10-08
Also published as: WO2024117949A1; AU2022489788A1

Abstract

A traffic control method performed by a traffic control system (200), for determining a safe performance of a specific task within an area of interest (240) in an underground environment, the traffic control system (200) comprises a control unit (270), the control unit (270) is configured to receive positioning data of machines (221-225) in the underground environment, wherein the method comprise: receiving (308) a request for a dedicated machine (221) to a perform a specific task during a specific time (t) within the area of interest (240), and thereby determining (310) a total amount of machines (221-225) in the underground environment, wherein the total amount of machines includes the dedicated machine (221) and all other machines (222-225). The method further comprises determining (312) a position of all machines (221-225) in the underground environment and determining (314) that the position of all other machines (222-225) is outside the area of interest (240) and a threshold distance (Dt) away from the area of interest (240).

Description

TRAFFIC CONTROL METHODS AND SYSTEMS FOR DETERMINING A SAFE PERFORMANCE OF A SPECIFIC TASK WITHIN A SAFETY AREA IN AN UNDERGROUND ENVIRONMENT

TECHNICAL FIELD

[0001 ] The present disclosure relates generally to traffic control methods and systems for determining a safe performance of a specific task within a safety area in an underground environment. The present disclosure also relates to a mine which comprises the traffic control system.

BACKGROUND

[0002] In an underground environment, such as an underground mine, a plurality of devices can be allocated to perform a variety of tasks. For example, a plurality of machines can be located in the mine to perform mining related tasks. In order to ensure that the mining tasks can be performed efficiently, it is often necessary to determine the positions of the machines and from that allocate tasks to a suitable machine. Since the mine is underground, conventional positioning systems, such as GPS, cannot be used. There is therefore a need to use a dedicated underground positioning system to determine the positions of the machines.

[0003] Due to the unreliable connection and transmission conditions in a mine, which can have narrow and turning mine tunnels, and also potential obstructions from objects, such mining machines, a local positioning system within the mine are mostly unpredictable, when e.g., a machine that has lost its communication connection, cannot be positioned.

[0004] Machines with an unknown position in the mine become a problem when one or a plurality of machines needs to perform a task without disturbance of other machines. Independently of the art of the task, it is important to guarantee the safety within the area the one or plurality of machines is performing the task. [0005] Additionally, any collision and/or unplanned stop in the mine, would lead to a loss of productivity of the mine.

[0006] The area where the task is performed could be defined as an area of interest. An exemplary area of interest could be working areas of the machines, narrow passages or ramps in the mine. For example, due to its heavy load, a fully loaded mine truck does only has limited possibility to restart after a stop during a steep uphill. Hence, when a heavy loaded machine is climbing up such a ramp or ramp section, it needs free passage in that ramp or ramp section, otherwise the two machines may be forced to stop in the middle of the ramp or even collide, thus a safety hazard may be created. A ramp is therefore an exemplary area of interest.

[0007] Hence, there is a need for ensuring a correct positioning of any machine in the mine. Especially, there is a need for a simple and secure method and system, to ensure that an area of interest can be cleared when a machine requests or is requested to perform a task in the area of interest, that is, to ensure that there is no risk for any other machines to enter the area of interest, during the time when the machine is performing the dedicated task in the area of interest.

SUMMARY

[0008] It is an object of this disclosure to address at least some of the problems and issues outlined above. It is possible to achieve these objects and others by using methods, and machines and systems as defined in the attached independent claims. It is an object of this disclosure to suggest a traffic control method in an underground environment so that a specific task within an area of interest can be performed without interruptions. It is an object of this disclosure to make sure that an area of interest is guaranteed to be clear when a machine is going to perform a task within it. It is also an object of this disclosure to suggest a simple and high efficiency traffic control in the underground environment. It is possible to achieve one or more of these objects, and possibly others, by using methods, machines and systems as defined in the attached independent claims. [0009] All objects of this disclosure are achieved by determining the positions of all the machines in the underground environment. The determination of the positions of all machines is used in order to clear an area of interest, instead of relying of high-resolution, real-time positioning of all the machines in the whole mine. One exemplary effect of this solution is that an unlimited number of area of interests can be defined within the underground environment, which all can be independent of each other and replace any physical boundary monitoring systems, such as a light curtain system. Additionally, an area of interest can be dynamic, i.e. , the area within which a dedicated task is performed, can be adapted to current requirements depending on where the dedicated machine is in a work schedule of the dedicated task.

[00010] According to one aspect, a traffic control method performed by a traffic control system is provided for determining a safe performance of a specific task within an area of interest in an underground environment. The traffic control system comprises a control unit, the control unit is configured to receive positioning data of machines in the underground environment, wherein the method comprise:

- receiving a request for a dedicated machine to a perform a specific task during a specific time within the area of interest, and thereby

- determining a total amount of machines in the underground environment, wherein the total amount of machines includes the dedicated machine and all other machines;

- determining a position of all machines in the underground environment

- determining that the position of all other machines is outside the area of interest and a threshold distance away from the area of interest, whereby the threshold distance is dependent on the specific time.

[00011] The dedicated task is a task performed by a machine in the underground environment. Non-limiting exemplary dedicated tasks are; a transport assignment from one position in the mine, to another position in the mine, and/or drilling and/or excavating and/or loading/unloading goods such as rock and/or ore. In practice, a plurality of tasks can be assigned to a plurality of machines within the area of interest simultaneously, where the machines may be assigned to cooperate to solve their respective dedicated task.

[00012] The dedicated machine is the machine that performs the specific task.

[00013] The specific time is the time which is needed to perform the dedicated task.

[00014] The area of interest is the area within the dedicated machine performs the dedicated task. The area of interest can be broken down to a plurality of subareas, and can also be dynamic, dependent e.g., on how far the dedicated machine has come in its work schedule in performing the dedicated task.

[00015] All other machines or unauthorised machines are machines that does not take part in performing the specific task and/or are not allowed within the area of interest when the dedicated machine is operating. Non-limiting examples of unauthorised machines are manual operated machines, or machines performing tasks that might interfere with the specific task of the dedicated machine.

[00016] Since the traffic control method determines the position of all the machines in the underground environment it can be verified that none of the unauthorised machines are inside the area of interests by the confirming that no unauthorised machine is located inside the area of interests. And furthermore, due to that all other machines must be a threshold distance away, and that the threshold distance is a function of the specific time, it is ensured not just that there are no unauthorised machines within the area of interest, but also that they cannot reach the dedicated area within the specific time. This enables the use a positioning system with a potential delay, i.e. , low accuracy, both in time and spatial positioning, in comparison to a safety system and method that must rely upon high accuracy positioning of machines.

[00017] The underground environment can be a whole mine or a delimited part of a mine within the underground environment, where the total number of machines can be determined. Due to the special circumstances in an underground environment, with a limited number of entrances/exits, the total number of machines can be relatively easy and with high accuracy be determined. An entrance/exit registration for all machines passing the entrance/exit can ensure that the total number of machines are updated at all times.

[00018] In the context of this disclosure, a machine can be any machine or vehicle in the underground environment.

[00019] The method uses positioning data, which can be determined through a positioning system in the underground environment. Normally, a mine is provided with a positioning system. One exemplary effect of the suggested method is that it can use the already provided positioning system of the mine, independent of its resolution. The positioning system can comprise of a specific sensor type or a plurality of sensor technologies, non-limiting examples are radio-frequency identification (RFID) positioning, near filed communication (NFC), light curtain positioning, access point positioning and/or beacon positioning. Light curtain positioning may refer to that if a known machine is passing a series of light curtains, and no other machines are in the vicinity of the series of light curtains, the specific machine’s position can be related to the passage of a specific light curtain.

[00020] In one exemplary embodiment of the traffic control method the method may further comprise:

- allowing the dedicated machine to perform the specific task, during the specific time, in the area of interest, or

- blocking the dedicated machine to perform the specific task, during the specific time, in the area of interest,

- depending on the determined position and threshold distance of all other machines.

[00021] The allowing and blocking may be executed by transmitting a control signal to the dedicated vehicle. When the dedicated vehicle receives the control signal it can, for example, trigger an optical indicator in the machine, which can be interpreted by an operator or the machine. Alternatively, a local controller of the machine can interpret the signal autonomously to start performing its tasks or to await a signal of allowance.

[00022] In one exemplary embodiment of the traffic control method, the position of each of the machines may be determined by;

- using the last known position of the machine and

- adjusting the threshold distance dependent on the age of the last known position of the machine.

[00023] One exemplary effect of using the last known position of the machine and adjusting the threshold distance, instead of e.g., a real time position, is that even machines where a current position cannot be obtained, e.g., due to bad reception in the underground environment, can be positioned, whereby it still can be determined if the area of interest is free of other machines during the time it takes to perform the dedicated task.

[00024] If the current position of a machine is unavailable, the last known position of respective machines can be used to determine if all the unauthorized machines are located outside the area of interest. Furthermore, by adding the threshold distance to the last known position of a machine, the method can use the last known position, and still determine that the machine, is not within the area of interest, or will not be able to reach it within the specific time. Normally, the longer since the last known position where determined, the longer becomes the threshold distance.

[00025] In one exemplary embodiment of the traffic control method, the threshold distance may be machine specific, and the machine specific threshold distance is determined by; determining a last known traveling direction of a machine, and - adjusting the threshold distance dependent on the last known traveling direction of the respective machine.

[00026] One exemplary effect thereof is, that by adapting the threshold distance to the respective machine’s respective prerequisite, a higher precision of the method is achieved, due to that specific threshold of a machine can be adjusted dependent on that machine’s specification, e.g., if the size of a machine is large, the specific threshold of the machine is longer. This can bring fewer false negatives, where machines are indicated to be inside the area of interest or be able to reach the area of interest within the specific time will be received.

[00027] In one exemplary embodiment of the traffic control method the machine specific threshold may be further determined by;

- determining a machine maximum speed, and/or

- determining the last known machine speed, and/or

- determining the machines planned route in the underground environment, and/or

- determining the type of machine and/or

- determining the dimensions of the machine, and thereby

- adjusting the threshold distance dependent on the maximum speed, and/or last known speed, and/or planned route in the underground environment, and/or type of machine, and/or dimensions of the machine.

[00028] In one exemplary embodiment of the traffic control method, the specific task may be related to traveling a certain distance within the area of interest.

[00029] According to another aspect, a machine is provided for performing a dedicated task during a specific time in an underground environment. The machine is adapted to request to perform a dedicated task during a specific time, in an area of interest and perform the dedicated task upon receiving a start signal from a traffic control system. [00030] According to another aspect, a traffic control system is provided for determining the safe performance of a specific task within an area of interest in an underground environment. The traffic control system comprises a control unit, the control unit is configured to receive positioning data of machines in the underground environment. The traffic control system is configured to receive a request for a dedicated machine to a perform a specific task during a specific time t within the area of interest and thereby determine a total amount of machines in the underground environment, wherein the total amount of machines includes the dedicated machine and all other machines. The traffic control system is further configured to determine a position of all machines in the underground environment and determine that the position of all other machines is outside the area of interest and a threshold distance Dt away from the area of interest.

[00031 ] Exemplary embodiments of the traffic control system may be configured to perform the steps of any embodiment of the disclosed traffic control method.

[00032] An exemplary embodiment of the traffic control system may comprise a positioning system, which provides the control unit with the positioning data.

[00033] Further possible features and benefits of this solution will become apparent from the detailed description below.

Brief Description of Drawings

[00034] The solution will now be described in more detail by means of exemplary embodiments and with reference to the accompanying drawings, in which:

[00035] Fig. 1 shows a schematic and exemplary traffic control system in an exemplary underground environment.

[00036] Fig. 2 shows a flow chart illustrating a method performed by a traffic control system according to an embodiment.

[00037] Fig. 3 shows a schematic block diagram of a machine with a threshold distance Dt according to an embodiment. Detailed Description

[00038] Fig. 1 shows an exemplary traffic control system 200 in an underground environment in a mine. The mine includes a main tunnel 260 and multiple smaller tunnels. Machines 221-225 are provided in the mine to perform different tasks. The reference numbers 221-225 in fig. 1 are just schematic and fewer or more machines can be provided. The machines 221-225 can move around in the underground environment and perform their task at different locations. An exemplary area of interest 240 is marked in the figure. The area of interest 240 can be a safety area, e.g., a ramp or a tunnel, or any area defined by a machine, an operating system or operator.

[00039] When a dedicated machine 221 is performing a specific and time critical task in the area of interest 240, other machines are not allowed in the area of interest 240 during that time. As already mentioned in the background, due to the specialty of the underground environment, conventional positioning systems, e.g., GPS, cannot be used in the mine to position the different machines. But there is a need to position the machines 221-225 when they are performing tasks to monitor the working process in the mine. For this purpose, multiple positioning devices 201-208 are provided in the mine to dynamically monitor the positions of all the machines 221-225. The positioning devices 101-114 are schematically disclosed. Fewer or more positioning devices 201-208 can be deployed. As previous disclosed the positioning devices 221-225 can be any of the non-limiting examples non-limiting examples are radio-frequency identification (RFID) positioning, near filed communication (NFC), light curtain positioning, access point positioning and/or beacon positioning.

[00040] The traffic control system and method according to this disclosure can use existing positioning devices 201-208 to determine the positions of the machines 221-225, independently if they have a high or low resolution or even delay in acquiring a machines position. This is due to the inverted positioning methodology, where the positions of all machines are determined to clear the area of interest 240. [00041] The traffic control system 200 comprises a control unit 270. The control unit 270 can be any type of control circuit, a centrally arranged control unit 270, a cloud-based control unit 270, a local control unit 270, a distributed control unit 270 or any combination thereof. The method performed by the traffic control system 200 is discussed in fig. 2.

[00042] Fig. 1 , in conjunction with fig. 2, describes a method performed by the traffic control system 200. The method is used for determining a safe performance of a specific task within an area of interest 240 in an underground environment. The control unit 270 is configured to receive positioning data of machines 221-225 in the underground environment. The transfer of positioning data from the positioning system can be wired or wireless or a combination thereof, depending on what is most suitable in the specific underground environment. The method comprises receiving 308 a request for a dedicated machine 221 to perform a specific task during a specific time t within the area of interest 240. The method further comprises determining 310 a total amount of machines 221-225 in the underground environment, wherein the total amount of machines includes the dedicated machine 221 and all other machines 222-225. The method further comprises determining 312 a position of all machines 221-225 in the underground environment and determining 314 that the position of all other machines 222-225 is outside the area of interest 240 and a threshold distance Dt away from the area of interest 240, whereby the threshold distance Dt is dependent on the specific time t.

[00043] The area of interest 240 can be any area in which a specific task is to be performed. For example, it can be a ramp, one or more sections of tunnels, a safety area, etc. The area of interest 240 can, e.g., be defined by the dedicated machine 221 which is going to perform the specific task in the area of interest 240 or be defined by the traffic control system or be a predefined area of interest.

[00044] The control unit 270 receives positioning data of machines 221 -225 from the positioning devices. The positioning data of the machines 221-225 is determined by the positioning devices 201-208. A variety of positioning technologies can be used by the positioning devices 201-208, e.g., Radio- frequency identification (RFID) positioning, near filed communication (NFC), light curtain positioning, access point positioning, beacon positioning. Since the traffic control method and traffic control system is not dependent on real time positioning data, the amount of the positioning devices 201-208 can be lower and/or with lower resolution than conventional positioning system. For example, the position of the machine 222 might be determined by the nearest positioning device 202. Since the distance between the positioning device 202 and the machine 222 can be long, and there might be tunnel walls in between, the accuracy of the positioning data for the machine 222 might be low, or the positioning device 202, might not been able to locate the machine 222. However, as be explained further on, the low accuracy positioning data will be enough for when implementing the methodology of this disclosure. The control unit 270 can receive the positioning data from the positioning devices wirelessly or wired.

[00045] In method step 308, the traffic control system 200 receives a request from the dedicated machine 221 . The request from the dedicated machine 221 indicates that the machine 221 requests to perform a specific task in the area of interest 240 during a specific time t.

[00046] In method step 310, the total amount of machines 221-225 in the mine is determined. The total number of machines can be determined by the positioning system. The positioning system is set up in such a manner that an entrance and exit of a machine 221-225 the underground environment of a machine is detected. The entrance/exit detection system can be any relevant sensor, e.g., radio-frequency identification (RFID) positioning, near filed communication (NFC), access point positioning, beacon positioning, which can detect a position of a specific machine. Therefore, the traffic control system 200 is updated on the total number of machines in the mine. The total number of machines includes the dedicated machine 221 and all the other machines 222- 225.

[00047] In method step 312, the positions of the all the machines 221-225 are determined, based on the received positioning data, including the position of the dedicated machine 221 and all other machines 222-225. [00048] In method step 314, based on the determined positions of all the machines 221-225, the traffic control system 200 determines that all other machines 222-225 are outside the area of interest 240 and a threshold distance Dt away from the area of interest 240. When the other machines 222-225 are determined to be outside the area of interest 240, and they have a threshold distance Dt away from the area of interest 240, it means that the other machines 222-225 is outside the area of interest 240 and would not arrive at the area of interest 240 within the specific time period t. The area of interest 240 is thereby cleared from other machines 222-225 during the specific time period t, whereby an uninterrupted performing of the dedicated task can be achieved and thereby and increased safety is realized, even with a low resolution or aged positioning data.

[00049] By this method, it can be ensured that no unauthorized machine will enter the area of interest 240 when the dedicated machine 221 is performing a specific task in the area of interest 240. This can be ensured with a minimal number of positioning devices and in most underground mine cases by using already existing positioning systems.

[00050] According to one exemplary embodiment, the method further comprises allowing the dedicated machine 221 to perform the specific task, during the specific time, in the area of interest 240, or blocking the dedicated machine 221 to perform the specific task, during the specific time, in the area of interest 240, depending on the determined position of all other machines 222-225.

[00051] When it is determined that all other machines are outside the area of interest 240 and have a distance higher than threshold distance Dt away from the area of interest 240, the dedicated machine 221 is allowed to perform the specific task. When it is determined that any of the other machines is inside the area of interest 240 or has a distance lower than the threshold distance Dt away from the area of interest 240, the dedicated machine 221 is blocked to perform the specific task, or just not get an allowance signal, since there is a risk that the other machine may move into the area of interest 240. [00052] According to one exemplary embodiment, the position of each of the machines 221-225 is determined by using the last known position of the machine 221-225 and adjusting the threshold distance Dt dependent on the age of the last known position of the machine 221-225.

[00053] The latest position data of a machine can vary in age dependent on factors such as update frequency or the possibility for the positioning system to locate a specific machine at the given time. The traffic control system 200 thereby uses the last known position of the machine to determine the current position of the machine. The threshold distance Dt represents a theoretical distance that the machine could have traveled during the time since the last known position was registered. The threshold distance Dt can thereby be adjusted depending on the age of the last known position. For example, the threshold distance Dt is increased if the age of the last known position is older, and the threshold distance Dt can decrease if the age of the last known position is younger.

[00054] According to one exemplary embodiment, the threshold distance Dt is machine specific and, determining a machine specific threshold by determining a last known traveling direction of a machine 222-225, and adjusting the threshold distance Dt dependent on the last known traveling direction of the machine 222- 225.

[00055] The threshold distance Dt is machine specific and different from machine to machine. The machine specific threshold is determined and adjusted by a last known traveling direction of the machine. For example, the threshold distance Dt is increased if the machine 222-225 is traveling towards the area of interest 240, and the threshold is decreased if the machine 222-225 is traveling away from the area of interest 240.

[00056] According to one exemplary embodiment, the machine specific threshold Dt is further determined by: determining a machine maximum speed, and/or determining the last known machine speed, and/or determining the machines 222-225 planned route in the underground environment, and/or determining the type of machine 222-225 and/or determining the dimensions of the machine 222-225, and thereby adjusting the threshold distance Dt dependent on the maximum speed, and/or last known speed, and/or planned route in the underground environment, and/or type of machine 222-225, and/or dimensions of the machine 222-225.

[00057] By providing machine specific thresholds Dt, a more accurate method is achieved, where fewer machines will be determined to be within reach of the area of interest, which will have a higher possibility to be cleared for the dedicated machine, with maintained or even raised safety standards.

[00058] According to one exemplary embodiment, the specific task is related to traveling a certain distance within the area of interest 240.

[00059] In this embodiment, the time for an unauthorized machine 222-225 to travel the threshold distance Dt is equal to or higher than the specific time for the dedicated machine 221 to travel the certain distance within the area of interest 240. By this method, the dedicated machine 221 would not be disturbed when traveling in the area of interest 240, because any unauthorized machine cannot reach the area of interest within the specific time due to the threshold distance.

[00060] Referring to fig. 3, a dedicated machine 221 and one of the other machines 222-225 are disclosed. The one other machine 222-225 is a threshold distance Dt away from the area of interest 240.

[00061] According to one exemplary embodiment, a machine 221 is provided for performing a dedicated task, during a specific time, in an underground environment, wherein the machine 221 is adapted to request to perform a dedicated task during a specific time, in an area of interest 240, and perform the dedicated task upon receiving a start signal from a traffic control system 200.

[00062] According to one exemplary embodiment, a traffic control system 200 is provided for determining a safe performance of a specific task within an area of interest 240 in an underground environment, the traffic control system 200 comprises a control unit 270, the control unit 270 is configured to receive positioning data of machines 221-225 in the underground environment, wherein the traffic control system 200 is configure to: receive 308 a request for a dedicated machine 221 to a perform a specific task during a specific time t within the area of interest 240, and thereby determine 310 a total amount of machines 222-225 in the underground environment, wherein the total amount of machines includes the dedicated machine 221 and all other machines 222-225; determine 312 a position of all machines 221-225 in the underground environment; determine 314 that the position of all other machines 222-225 is outside the area of interest 240 and a threshold distance Dt away from the area of interest 240.

[00063] According to one exemplary embodiment, the traffic control system 200 is further configured to: allow the dedicated machine 221 to perform the specific task, during the specific time, in the area of interest 240, or block the dedicated machine 221 to perform the specific task, during the specific time t, in the area of interest 240, depending on the determined position of all other machines 222-225.

[00064] According to one exemplary embodiment, the position of each of the machines 221-225 is determined by using the last known position of the machine 221-225 and adjusting the threshold distance Dt dependent on the age of the last known position of the machine 221-225.

[00065] According to one exemplary embodiment, the threshold distance Dt is machine specific and, determining a machine specific threshold Dt by determining a last known traveling direction of a machine 222-225, and adjusting the threshold distance Dt dependent on the last known traveling direction of the machine 222- 225.

[00066] According to one exemplary embodiment, the machine specific threshold Dt is further determined by determining a machine maximum speed, and/or determining the last known machine speed, and/or determining the machines 222- 225 planned route in the underground environment, and/or determining the type of machine 222-225 and/or determining the dimensions of the machine 222-225, and thereby adjusting the threshold distance Dt dependent on the maximum speed, and/or last known speed, and/or planned route in the underground environment, and/or type of machine 222-225, and/or dimensions of the machine 222-225.

[00067] According to one exemplary embodiment, the specific task is related to traveling a certain distance within the area of interest 240.

[00068] Although the description above contains a plurality of specificities, these should not be construed as limiting the scope of the concept described herein but as merely providing illustrations of some exemplifying embodiments of the described concept. It will be appreciated that the scope of the presently described concept fully encompasses other embodiments which may become obvious to those skilled in the art, and that the scope of the presently described concept is accordingly not to be limited. Reference to an element in the singular is not intended to mean "one and only one" unless explicitly so stated, but rather "one or more." Further, the term “a number of’, such as in “a number of wireless devices” signifies one or more devices. All structural and functional equivalents to the elements of the above-described embodiments that are known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed hereby. Moreover, it is not necessary for an apparatus or method to address each and every problem sought to be solved by the presently described concept, for it to be encompassed hereby. In the exemplary figures, a broken line generally signifies that the feature within the broken line is optional.

Claims

1 . A traffic control method performed by a traffic control system (200), for determining a safe performance of a specific task within an area of interest (240) in an underground environment, the traffic control system (200) comprises a control unit (270), the control unit (270) is configured to receive positioning data of machines (221-225) in the underground environment, wherein the method comprise:

- receiving (308) a request for a dedicated machine (221 ) to perform a specific task during a specific time (t) within the area of interest (240), and thereby

- determining (310) a total number of machines (221-225) in the underground environment, wherein the total number of machines includes the dedicated machine (221 ) and all other machines (222-225);

- determining (312) a position of all machines (221-225) in the underground environment

- determining (314) that the position of all other machines (222-225) is outside the area of interest (240) and a threshold distance (Dt) away from the area of interest (240), whereby the threshold distance (Dt) is dependent on the specific time (t).

2. The traffic control method as claimed in claim 1 , wherein the method further comprises:

- allowing the dedicated machine (221) to perform the specific task, during the specific time, in the area of interest (240), or

- blocking the dedicated machine (221) to perform the specific task, during the specific time (t), in the area of interest (240), depending on the determined position of all other machines (222-225).

3. The traffic control method as claimed in claim 1 or 2, wherein the position of each of the machines (221-225) is determined by;

- using the last known position of the machine (221-225) and - adjusting the threshold distance (Dt) dependent on the age of the last known position of the machine (221-225).

4. The traffic control method as claims in any of the preceding claims, wherein the threshold distance (Dt) is machine specific and, determining a machine specific threshold distance (Dt) by;

- determining a last known traveling direction of a machine (222-225), and

- adjusting the threshold distance (Dt) dependent on the last known traveling direction of the machine (222-225).

5. The traffic control method as claims in claim 3, wherein the machine specific threshold (Dt) is further determined by;

- determining a machine maximum speed, and/or

- determining the last known machine speed, and/or

- determining the machines (222-225) planned route in the underground environment, and/or

- determining the type of machine (222-225) and/or

- determining the dimensions of the machine (222-225), and thereby

- adjusting the threshold distance (Dt) dependent on the maximum speed, and/or last known speed, and/or planned route in the underground environment, and/or type of machine (222-225), and/or dimensions of the machine (222-225).

6. The traffic control method as claimed in any of the preceding claims, wherein the specific task is related to traveling a certain distance within the area of interest (240).

7. Machine (221 ) for performing a dedicated task, during a specific time, in an underground environment, wherein the machine (221 ) is adapted to: request to perform a dedicated task during a specific time, in an area of interest (240), and perform the dedicated task upon receiving a start signal from a traffic control system (200).

8. A traffic control system (200) for determining a safe performance of a specific task within an area of interest (240) in an underground environment, the traffic control system (200) comprises a control unit (270), the control unit (270) is configured to receive positioning data of machines (221-225) in the underground environment, wherein the traffic control system (200) is configured to:

- receive (308) a request for a dedicated machine (221 ) to perform a specific task during a specific time (t) within the area of interest (240), and thereby

- determine (310) a total number of machines (222-225) in the underground environment, wherein the total number of machines includes the dedicated machine (221 ) and all other machines (222-225);

- determine (312) a position of all machines (221-225) in the underground environment

- determine (314) that the position of all other machines (222-225) is outside the area of interest (240) and a threshold distance (Dt) away from the area of interest (240).

9. The traffic control system (200) as claimed in claim 8, wherein the traffic control system (200) is further configured to:

- allow the dedicated machine (221 ) to perform the specific task, during the specific time, in the area of interest (240), or

- block the dedicated machine (221 ) to perform the specific task, during the specific time (t), in the area of interest (240), depending on the determined position of all other machines (222-225).

10. The traffic control system (200) as claimed in claim 8 or 9, wherein the position of each of the machines (221-225) is determined by;

11 . The traffic control system (200) as claims in any of the preceding claims, wherein the threshold distance (Dt) is machine specific and, determining a machine specific threshold (Dt) by;

- determining a last known traveling direction of a machine (222-225), and

12. The traffic control method as claims in claim 10, wherein the machine specific threshold (Dt) is further determined by;

- determining a machine maximum speed, and/or

- determining the last known machine speed, and/or

- determining the type of machine (222-225) and/or

- determining the dimensions of the machine (222-225), and thereby

13. The traffic control system (200) as claimed in any of the preceding claims, wherein the specific task is related to traveling a certain distance within the area of interest (240).