Monitoring a volume of an underground work site

Abstract

Disclosed is a mobile passage control unit, a method and a computer program product for obtaining three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes, determining, based on the three-dimensional reference data, a set of initially unoccupied sub-volumes within the monitored volume, obtaining, by the sensing device, three-dimensional sensing data relating to the monitored volume, examining obtained three- dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume, detecting, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one sub-volume in the set of initially unoccupied sub-volumes becoming an occupied sub-volume, and determining, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

Description

[0001] Monitoring a Volume of an Underground Work Site

[0002] Field

[0003] The present application relates to monitoring a volume of an underground work site and using a device configured to obtain sensing data for the monitoring.

[0004] Background

[0005] In underground work sites, such as mines, conditions may be challenging for executing the work. In addition, work machines used in underground work sites may be powerful and heavy and therefore their safe usage is important. Various measures may be taken to ensure that work in an underground work site can be carried out in a safe manner. Some of these measures may include using technology to that helps to enable safety.

[0006] Brief Description

[0007] The scope of protection sought for various embodiments of the invention is set out by the independent claims. The example embodiments and features, if any, described in this specification that do not fall under the scope of the independent claims are to be interpreted as examples useful for understanding various embodiments of the invention.

[0008] According to a first aspect there is provided mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three-dimensional sensing data relating to the volume, the mobile passage control unit comprising means for: obtaining three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes, determining, based on the three- dimensional reference data, a set of initially unoccupied sub-volumes within the monitored volume, obtaining, by the sensing device, three-dimensional sensing data relating to the monitored volume, examining obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume, detecting, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one subvolume in the set of initially unoccupied sub-volumes becoming an occupied subvolume, and determining, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

[0009] In some exemplary embodiments according to the first aspect, the means comprises at least one processor, and at least one memory, including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the performance of the apparatus.

[0010] According to a second aspect there is provided a mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three-dimensional sensing data relating to the volume, the mobile passage control unit further comprising at least one processor, and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the mobile passage control unit to: obtain three- dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes, determine, based on the three-dimensional reference data, a set of initially unoccupied sub -volumes within the monitored volume, obtain, by the sensing device, three-dimensional sensing data relating to the monitored volume, examine obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume, detect, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one sub -volume in the set of initially unoccupied sub-volumes becoming an occupied sub-volume, and determine, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume. According to a third aspect there is provided a method for monitoring a volume of an underground work site using a mobile passage control unit, the mobile passage control unit comprising a sensing device configured to provide three-dimensional sensing data relating to the volume, the method comprising: obtaining three- dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes, determining, based on the three-dimensional reference data, a set of initially unoccupied sub -volumes within the monitored volume, obtaining, by the sensing device, three-dimensional sensing data relating to the monitored volume, examining obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume, detecting, based on the examining, at least one change event in the set of initially unoccupied sub -volumes, the at least one change event comprising at least one sub -volume in the set of initially unoccupied sub-volumes becoming an occupied sub-volume, and determining, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

[0011] In some example embodiments according to the third aspect, the method is a computer-implemented method.

[0012] According to a fourth aspect there is provided a computer program for a mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three- dimensional sensing data relating to the volume, the computer program comprising instructions for causing the mobile passage control unit to perform at least the following: obtain three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes, determine, based on the three-dimensional reference data, a set of initially unoccupied sub-volumes within the monitored volume, obtain, by the sensing device, three-dimensional sensing data relating to the monitored volume, examine obtained three-dimensional sensing data relating to the set of initially unoccupied sub -volumes of the monitored volume, detect, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one subvolume in the set of initially unoccupied sub-volumes becoming an occupied subvolume, and determine, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

[0013] According to a fifth aspect there is provided a computer program for a mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three- dimensional sensing data relating to the volume, the computer program comprising instructions stored thereon for performing at least the following: obtaining three- dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes, determining, based on the three-dimensional reference data, a set of initially unoccupied sub -volumes within the monitored volume, obtaining, by the sensing device, three-dimensional sensing data relating to the monitored volume, examining obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume, detecting, based on the examining, at least one change event in the set of initially unoccupied sub -volumes, the at least one change event comprising at least one sub -volume in the set of initially unoccupied sub-volumes becoming an occupied sub-volume, and determining, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

[0014] According to a sixth aspect there is provided a non-transitory computer readable medium comprising program instructions for a mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three-dimensional sensing data relating to the volume, wherein the program instructions cause the mobile passage control unit to perform at least the following: obtain three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of subvolumes, determine, based on the three-dimensional reference data, a set of initially unoccupied sub -volumes within the monitored volume, obtain, by the sensing device, three-dimensional sensing data relating to the monitored volume, examine obtained three-dimensional sensing data relating to the set of initially unoccupied subvolumes of the monitored volume, detect, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one sub -volume in the set of initially unoccupied sub -volumes becoming an occupied sub-volume, and determine, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

[0015] According to a seventh aspect there is provided a non-transitory computer readable medium comprising program instructions stored thereon for a mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three- dimensional sensing data relating to the volume, wherein the computer program instructions are for performing at least the following: obtaining three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes, determining, based on the three-dimensional reference data, a set of initially unoccupied sub -volumes within the monitored volume, obtaining, by the sensing device, three-dimensional sensing data relating to the monitored volume, examining obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume, detecting, based on the examining, at least one change event in the set of initially unoccupied subvolumes, the at least one change event comprising at least one sub -volume in the set of initially unoccupied sub-volumes becoming an occupied sub-volume, and determining, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume. List of Drawings

[0016] In the following, the invention will be described in greater detail with reference to the embodiments and the accompanying drawings, in which

[0017] FIG. 1 illustrates an example embodiment of an underground work site.

[0018] FIG. 2 illustrates a safety system that may be used within an underground work site.

[0019] FIG. 3 illustrates an example embodiment in which an underground work site has a safety system that comprises mobile passage control units.

[0020] FIG. 4 illustrates an example embodiment of an underground work site.

[0021] FIG. 5A and FIG. 5B illustrate flow charts according to example embodiments.

[0022] FIG. 5C illustrates a block diagram according to an example embodiment.

[0023] FIG. 6 illustrates an example embodiment of an apparatus.

[0024] FIG. 7A and FIG. 7B illustrate examples oftop views ofvolumes configured to be monitored by an onboard mobile passage control unit.

[0025] FIG. 7C illustrates an example of a perspective view a volume configured to be monitored by an onboard mobile passage control unit.

[0026] FIG. 8 illustrates an example of visualization of an object detected within a monitored volume.

[0027] Description of Embodiments

[0028] The following embodiments are exemplifying. Although the specification may refer to "an”, "one”, or "some” embodiments) in several locations of the text, this does not necessarily mean that each reference is made to the same embodiments), or that a particular feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.

[0029] FIG. 1 illustrates an example embodiment of an underground work site 100. A work site may be understood as an area within which industrial operations may be performed. It is to be noted that a work site may also be understood as an operating site. An example of an underground work site 100 is a mine which comprises various tunnels and the walls of the tunnels are at least partly limited by rocks. When compared to a work site such as a factory or a terminal for handling cargo, an underground work site, such as the underground work site 100, differs in that it may not be as stable as an environment as a work site such as a factory or a terminal. In an underground work site, the environment may be changing due to tunnels being established as well as due to other work being performed. For example, in an underground work site due to work, such as drilling, being performed, there may be obstacles, such as rocks, appearing and causing a significant change to the environment. Also, the tunnels may change as a result of the work being performed. Therefore, when comparing for example a mine and a factory, the mine may be considered as a less stable environment than the factory.

[0030] As the underground work site 100 is an area for industrial operations, there may be work machines, such as mining vehicles 102, 104, 106 used for industrial operations, operating within the underground work site 100. The mining vehicles 102, 104, 106 may be mobile meaning that the mining vehicles may be configured to move within the operating site 100. In some example embodiments, at least some of the mining vehicles 102, 104 and 106 may be partially or fully automated mining vehicles that are capable of performing operations autonomously without, or with limited, control from a user, that may be a person working in the underground work site 100. For example, the person may work in a remote location, such as a monitoring room, of the underground work site 100, and thus be capable of controlling the automated, or partially automated, mining vehicle remotely. An automated mining vehicle may be configured to autonomously perform one or more tasks. It is to be noted that the one or more tasks may be comprised in an operation that can be performed by a work machine such as a mining vehicle and as such, a work machine, when operating, may perform one or more tasks. An automated mining vehicle operating in an automatic mode may be configured to, for example, receive a task to be performed, perceive the environment of the mining vehicle, as the mining vehicle is a mobile mining vehicle, and autonomously perform the task while taking the environment into account. It is to be noted though that for example due to safety aspects, an automated, or partially automated mining vehicle configured to operate independently may be taken into control by an external entity at any time. The external entity may be for example a user or a safety system or any other suitable external entity. Examples of mining vehicles such as the mining vehicles 102, 104 and 106, comprise trucks, bulldozers, dumpers, vans, rock drilling or milling rigs, gantry cranes, mobile reinforcement machines, mechanical cutting machines and loaders, or any other kind of work machines suitable for performing an operation within the underground work site 100.

[0031] The underground work site 100 may be divided into different areas such as areas 110 and 120, which may also be understood as operation zones within the underground work site 100. By dividing the underground work site 100 into smaller areas, there may be an advantage that some operations may be limited to certain area and / or access may be limited to some parts of the underground work site 100. For example, the area 110 may be reserved for automated mining vehicles such that manually operated mining vehicles and / or personnel is not allowed to enter the area 110 unless operations performed by the autonomous mining vehicles are stopped. Thus, the area 110 may be called as an isolated working area, or a safety area, or an isolated safety area. It is to be noted though that an area may be isolated such that it is an isolated safety area for any other suitable reason as well. An isolated safety area may be reserved for at least one mining vehicle, that is a mobile mining vehicle, operating in a particular mode of operation. A mode of operation may comprise, for example, an automatic mode comprising autonomous operation of the automated mining vehicle or manual mode comprising manual operation of the mining vehicle. An isolated safety area may, therefore, be reserved for one or more automated mining vehicles or one or more manually operated mining vehicles. Reserving an area, within the underground work site 100, may comprise providing restricted access to the area by one or more passage control units. Additionally, or alternatively, in some example embodiments, there may also be areas within an underground work site to which access is restricted although the area is not isolated as such. The restrictions made to entering an area, for whatever reason, may be permanent or they may be temporary.

[0032] An isolated safety area may be isolated using one or more passage control units that comprise a mechanism configured to perform passage control. A passage control unit may comprise a physical access barrier for restricting access by work machines, such as mining vehicles, to the isolated safety area and preventing unauthorized personnel from entering the isolated safety area when one or more mobile mining vehicles are operating within the isolated safety area. For example, a passage control unit may comprise an access barrier such as a gate. A passage control unit may comprise, for example, an electronic access barrier. Alternatively, in some other example embodiments, any other suitable passage control mechanism may be utilized in a passage control unit. A passage control unit may further comprise at least one sensing device for detecting people and / or mining vehicles entering and / or exiting the isolated working area. A sensing device, which may also be understood as a detection device, may comprise, for example, a light curtain, or some other suitable detection device. One or more passage control units may be comprised in, or connected to, a safety system that is configured to monitor safety of the isolated safety area 110. Further, the one or more passage control units may be operatively coupled to a system that is configured to monitor the underground work site 100 as a whole. The system may be configured to communicate with one or more communication units located within the underground work site 100. A communication unit may comprise, for example, a communication unit included in a mining vehicle, a communication unit included in a cap lamp of a person, or a communication unit included in a structure such as a communication unit included in a passage control unit. Communicating with one or more communication units may comprise receiving information from and / or sending information to the one or more communication units. For example, the system may be configured to receive data from the operating site 100 as well as from mining vehicles, user etc. The system may also be configured to provide data and / or instructions to mining vehicles within the underground work site 100. The system may additionally, or alternatively, be configured to receive a user input from a person such as a person monitoring the operations within the underground work site 100.

[0033] According to an example embodiment, a passage control unit may be, or may comprise, a sensing device such as an optoelectronic guard detector, such as a guard detector based on the use of a light curtain or photocells. Alternatively, other kind of devices such as laser scanning devices, devices providing three-dimensional (3D) sensing data and safety mats, may be utilized to detect movement of a mobile object. Three-dimensional sensing data may be provided by using a sensing device such as a multi-layer lidar, a three-dimensional radar, a four-dimensional radar or ultrasonic sensing. A passage control unit may, in some example embodiments, be configured to detect the direction of motion of the mobile object. For example, the passage control unit may be configured to detect if the mobile object is entering or exiting the isolated safety area.

[0034] FIG. 2 illustrates a safety system that may be used within an underground work site such as the underground work site 100 of the example embodiment illustrated in FIG. 1. The safety system may be used for example with an isolated safety area such as area 110 illustrated in the example embodiment of FIG. 1. The safety system in this example embodiment comprises a control unit 210, which may be understood as a logical unit that comprises at least one controller. The control unit 210 is connected to functional units 220-250. It is to be noted that in some other example embodiments there may be different number of functional units the control unit 210 is connected to. The functional units 222, 224, 226, 232, 234, and 236 in this example embodiment are passage control units such as electronic access barriers. These functional units may be configured to detect movement to or from an isolated safety area. The movement may be caused for example by a mobile object such as a person, by a mining vehicle or any other mobile object. Additionally, or alternatively, the movement may be caused by a falling rock for example. The movement of the mobile object may be detected based on any suitable technology, for example, by a light curtain having one or more laser transmitters transmitting a laser beam across the passage-controlled part of the underground work site, based on visual information and / or based on 3D sensing data. The safety system is configured to receive an indication that may be interpreted, by the control unit 210 to indicate movement to or from an isolated safety area. The control unit 210 is configured to then determine a corresponding action. For example, the control unit 210 may be configured to send an indication to one or more mining vehicles within the operating site requesting them to perform a safety operation such as stopping and preventing movement of the mining vehicle. Further, the control unit 210 may be connected over any suitable network 260 to other devices and may also be configured to provide an indication of the detected movement to one or more other devices using the network 260. Additionally, the safety system may further comprise functional units that comprise identification units 230, 220. The identification units 220, 230 may be configured to identify the mobile object entering or exiting the isolated working area.

[0035] In this example embodiment, the safety system further comprises functional units 240 and 250 that comprise indication units. An indication unit may be comprised in a passage control unit in some other example embodiments. The indication units 240 and 250 may be configured to indicate further control information for the mobile object to enter into or exit from the isolated working area.

[0036] The safety system illustrated in this example embodiment may further comprise communication links between the functional units. A communication link may be established as a unidirectional or bidirectional communication link. The communication links may be based on any suitable technology. For example, the communication link may be based on a wireless local area networking, such as IEEE 802.11 or 802.16 based communications is applied.

[0037] The safety system of this example embodiment may also be connected to a control unit that is comprised in a mining vehicle located in the isolated working area. Thus, centralized safety control may be applied within the isolated working area. In some example embodiments, it may be a pre-requisite for a mining vehicle to enter into the isolated working area that it is connected to the safety system. For example, the safety system may be configured to transmit the indication for a safety operation to be performed to the mining vehicle located in the isolated safety area.

[0038] In an underground work site, as the work progresses, the production area may change and / or move due to the work performed. This may cause a need for changing an isolated safety area. Consequently, also the safety system, that comprises a plurality of passage control units may need to be changed. This may require a considerable amount of work when the passage control units are fixed to their location. For example, a light curtain pairs may need to be installed to walls and power, as well as a wired network connectivity, may need to be installed. After this the configuration of the safety system as a whole needs to be updated. The updating may comprise matching the physical setup to the configuration of the safety system. This may require that careful performing of the updating as when the configuration is made by humans and the safety system is at least partly placed differently and the placing is done manually, the updating may be prone to errors. Yet, there should be confidence that when an area within the underground work site is isolated, it is indeed properly and correctly isolated.

[0039] FIG. 3 illustrates an example embodiment in which an underground work site 300 has a safety system that comprises two passage control units 330 and 340 that are mobile in a sense that they are not fixed to their location but can easily be picked up and moved elsewhere if needed. Thus, the passage control units 330 and 340 may be understood as mobile passage control units. In this example embodiment, a tunnel 320 ofthe underground work site 300 is to be isolated. There is a mining vehicle 302 operating within the tunnel 320 and a mining vehicle 304 operating outside of the tunnel 320. The mining vehicle 304 is configured not to enter the tunnel 320 and there is a light curtain 310, which is also a passage control unit comprised in the safety system, to monitor for that. In this example embodiment, the light curtain is a passage control unit that comprises two separate elements, the element 312 and 314, that are placed at a distance between each other to create a space between the tunnel and an object approaching it. For example, if a person was to proceed towards the tunnel 320, the element 312 and the element 314 create a safety measure by providing a space between the tunnel and the person approaching it thus making it safer to either enter the space or react to the person approaching the tunnel in case the person should not enter the tunnel 320. The elements 312 and 314 may be any suitable elements, for example they may be lights curtains, a light curtain and a rope switch, etc.

[0040] The mobile passage control units 330 and 340 are connected to the same safety system as the light curtain 310. In this example embodiment, the mobile passage control units 330 and 340 thus are a part of the safety system and may be configured to connect to the safety system wirelessly using any suitable wireless communication. In this example embodiment, the mobile passage control units 330 and 340 are configured to have a constant communication to the system. The constant communication may be understood as sending data to the safety system continuously or at pre-determined time intervals. The safety system may be configured to indicate if the continuous communication is disturbed so that it can be checked if there is a problem with at least one of the mobile passage control units 330 or 340, and / or the safety system maybe configured to stop a mining vehicle 302 operating in the tunnel 320.

[0041] In general, a mobile passage control unit such as mobile passage control unit 330 or 340 can be considered as a detection device that covers and monitors a three- dimensional space that may be understood as a volume. The mobile passage control unit may be configured to sense, using a sensing device it comprises or is connected to, the volume using, for example, a multi-layer lidar, three-dimensional radar, a fourdimensional radar, or ultrasonic sensing. The mobile passage control unit is configured to provide three-dimensional data regarding the volume it is capable of detecting using its sensor(s), in other words, using sensing. Thus, the three- dimensional data may be understood as three-dimensional sensing data. The three- dimensional sensing data may be in any suitable format, it may be for example a point cloud. It is to be noted that three-dimensional sensing data may be represented using data frames and one data frame may comprise data points representative of distances from the sensing device to surrounding objects such as tunnel walls, obstacles, vehicles, or pedestrians at a particular time instance.

[0042] The sensing device may be able to sense a volume over a distance that is called a sensing distance and it may be, for example, up to 100 meters. This allows monitoring without having two separate elements as is the case with a passage control unit such as the light curtain 310. A volume the mobile passage control unit is configured to monitor, based on the sensing performed by the sensing device, may comprise a monitoring volume defined by a monitoring distance that is less than the sensing distance. The monitoring distance may be for example 10 to 50 meters. The monitoring distance may be determined by a user of the mobile passage control unit for example.

[0043] Using a mobile passage control unit that is able to sense a volume allows to monitor a three-dimensional space that may have any shape. As the monitoring distance can be defined up to the distance of the sensing distance, it allows to define an arbitrary three-dimensional space to be monitored. Further, in case a mobile passage control unit is placed at an intersection, such as an intersection of tunnels, it may allow monitoring in multiple directions using one passage control unit. The monitoring distance may be understood as a distance within an area monitored by the mobile passage control unit. The area may thus be called as monitored area. The monitored area may be defined, for example, as a radius or as cartesian distances to specific directions from the mobile passage control unit. It may also be determined as an arbitrary polygon shape. In some example embodiments, any detections outside the monitored area may be considered to be merely for information and may thus be excluded from monitoring that is for the purpose of safety. In this example embodiment, the mobile passage control unit 330 has a sensing distance 332 and a monitoring distance 334. The mobile passage control unit 340 has a sensing distance of 342 and a monitoring distance 344.

[0044] In some example embodiment's), the mobile passage control unit 330, 340 may be onboard the mining vehicle 302, 304. In other words, the mining vehicle 302, 304 may comprise the mobile passage control unit 330. The mobile passage control unit 330 may be configured to monitor volume(s) in proximity of the mining vehicle 302, 304. Examples of volumes configured to be monitored by an onboard mobile passage control unit of a mining vehicle are described with reference to in FIG. 7A, FIG. 7B, and FIG. 7C.

[0045] The volume monitored by a passage control unit such as passage control unit 330 or 340 may be defined using voxels. A voxel is a unit representative of a predefined volume of three-dimensional space. A voxel may comprise, for example, a cube. A part of the monitoring volume, which may be referred to as a sub-volume, may be defined using voxels. A group of voxels may be used to define a sub -volume of the monitored volume. A sub-volume may be an occupied sub-volume or an unoccupied subvolume. An occupied sub-volume comprises at least one occupied voxel while an unoccupied sub-volume is substantially free from occupied voxels. An occupied voxel comprises a voxel associated with sensing data indicative of an object. In case the object moves, it causes a change to the group of voxels that represent the sub-volume and thus, the movement may be detected. Correspondingly, in case a sub-volume is unoccupied, which may be understood as no unintended objects are present in the sub-volume, changes to the voxels representing that sub-volume may be understood as being indicative of movement of an object, and the sub-volume becomes occupied. This may be understood as a change event that may be indicative of a movement.

[0046] In order to avoid false positives, a further criterion may be applied before determining that the change event has occurred. For example, the change event is to be detected for a pre-determined threshold period that may be defined as time, or for example requiring that the change event is detected for three or five consecutive measurements performed by the sensing device. Additionally, or alternatively, the change event may be associated with a criterion that the change event detected in the sub-volume corresponds to a change event detected in an adjacent sub-volume as well.

[0047] A mobile passage control unit may be configured to monitor changes in one or more sub-volumes that are unoccupied. In this way it is possible to adapt to changes in an environment rather easily. Also, the monitoring may be set to detect for changes greater than a pre-determined threshold. A benefit of doing so is that the mobile passage control system becomes resistant to rain, dust or any falling or flying rocks. Instead, the mobile passage control system may be configured to indicate a change event when there is a change event corresponding to for example a person or a vehicle.

[0048] In this example embodiment, the mobile passage control units 330 and 340 together with the passage control unit 310 form a group of passage control units that isolate the area 320. This group, along with the safety system, may be comprised in a monitoring system. The mobile passage control unit 330 is configured to monitor at least one sub -volume within the volume defined by the monitoring distance 334, and the mobile passage control unit 340 is configured to monitor at least one sub-volume within the volume defined by the monitoring distance 344. If either of them detects a change event and at least one criterion relating to the change event is fulfilled, it may be determined that an object has been moving in the monitored volume. This determination may then be indicated to the safety system as well. For example, three- dimensional sensing data obtained from the sensing device may be determined as indicative of an object. Additionally, other data regarding the object may be provided to the safety system. The other data may be for example image-based data such as video feed or one or more images. Thus, information may be provided to the safety system. Additionally, or alternatively, the mobile passage control unit 330, or 340, maybe configured to compare one or more data frames and determine that the object is moving within the volume, for example such that the object is approaching the isolated area 320.

[0049] It is to be noted that in some example embodiments, a mobile passage control unit may be configured to monitor an additional volume outside the volume that is monitored. For example, the mobile passage control unit may be configured to monitor an additional volume extending for example about 5 meters beyond the monitored volume and in case movement is detected in the additional volume, the mobile passage control unit may cause an output to be provided. The output may be in any suitable format, for example a visual output or an audio output or a combination of both. The output may be used to warn that if the movement continues, there is an alarm caused to the safety system, which may then for example stop operations in the area which is isolated using the mobile passage control unit. Thus, this way it may be possible to prevent accidental alarms being caused as the monitored volume may not be visible.

[0050] FIG. 4 illustrates an example embodiment of an underground work site 400. In this example embodiment, the underground work site is a mine, but it could be a construction site for building tunnels or any other suitable underground work site as well. In this example embodiment, there is an isolated safety area 450 within the underground work site 400. The isolated safety area 450 is isolated using mobile passage control units 410, 420, 430 and 440.

[0051] For the isolated area 450 to be successfully isolated, the mobile passage control units 410, 420, 430 and 440 should be located in correct positions and activated. As the mobile passage control units 410, 420, 430 and 440 can be moved and set up manually in any location, there is a need to update their location and monitored volume such that there is a knowledge where in the underground work site 400 each mobile passage control unit is located. As a mobile passage control unit, such as the mobile passage control unit 410, 420, 430 or 440, is configured to sense three-dimensional data, it is capable of measuring the actual geometry of its surrounding environment, such as a tunnel. The mobile passage control unit may be comprised in a monitoring system along with a positioning unit. The positioning unit may be understood as a logical unit that is provided using for example a server such as a data management server. The mobile passage control unit may be configured to provide the sensing data to the positioning unit, or, alternatively, the positioning unit may be configured to obtain the sensed data in any other suitable manner.

[0052] The positioning unit may comprise a model of the underground work site 400. This model may comprise three-dimensional reference data to which the sensing data relating to the monitored volume may be compared. Based on this comparison, a position of the mobile passage control unit may be determined. Determining the position may comprise determining location and orientation of the mobile passage control unit. It is to be noted that the three-dimensional reference data may be associated with a coordinate frame of the underground work site. In other words, as the positioning unit comprises a model of the underground work site 400, the positioning unit is configured to match the received sensing data relating to the monitored volume to the model and determine the xyz -location and orientation of a mobile passage control unit based on the obtained sensing data in relation to the underground work site 400. It is to be noted that the sensing data relating to the monitored volume may comprise the monitored volume as well as additional volumes within the sensed volume.

[0053] The positioning unit may be configured to determine the position of the mobile passage control unit based on the three-dimensional sensing data and the three- dimensional reference data. The positioning unit may further be configured to provide information on the position of the mobile passage control unit to the mobile passage control unit, the information on the position comprising a location and orientation of the mobile passage control unit. Additionally, the positioning unit may be configured to update the model such that it comprises indication of the mobile passage control unit and its location. The model may further be updated to indicate the volume monitored by the mobile positioning unit and / or whether the mobile passage control unit is activated or not.

[0054] The mobile passage control unit is configured to detect a triggering event for determining a position of a mobile passage control unit in the underground work site 400. The mobile passage control unit may be configured to obtain the three- dimensional sensing data relating to the monitored volume by the sensing device as a response to detecting the triggering event. The triggering event may comprise an instruction-based triggering event or a data-based triggering event. The triggering event may comprise, for example, at least one of the following: receiving a user input, detecting a change in the three-dimensional sensing data that is greater than a predetermined threshold change, or receiving a command to obtain the three- dimensional sensing data. Thus, when the mobile passage control unit is activated, it may be determined as causing a triggering event. Additionally, or alternatively, the triggering event may be caused for example by providing a command or when then mobile passage control unit senses data indicative of a change that is interpreted as a change that causes a need to check the position of the mobile passage control unit. Optionally, the mobile passage control unit may be configured to receive a request to verify the location determined by the positioning unit for the mobile passage control unit.

[0055] Optionally, the monitoring system may also comprise one or more of the following: one or more additional mobile passage control units, a user interface, or safety system. As each mobile passage control unit comprised in the monitoring system may define a part of an isolated safety area, the user interface may be configured to illustrate, for example visually, successfully isolated one or more safety areas within the underground work site. The positioning unit may be configured to determine the part of an isolated safety area defined by an individual mobile passage control unit. The safety system may be the safety system of the underground work site and it may be comprised in the monitoring system, or the monitoring system may be connected to the safety system.

[0056] In the example embodiment of FIG. 4, the monitoring system comprises the mobile passage control units 410, 420, 430 and 440. When activated, these mobile passage control units isolate a safety area 450 within the underground work site 400. As the positioning unit comprised in the monitoring system is aware of the status and location of the mobile passage control units 410, 420, 430 and 440, it is able to illustrate on the model to indicate the area 450 as a successfully isolated safety area based on the status of the mobile passage control units 410, 420, 430 and 440. Thus, the positioning unit may be configured to provide information, which may comprise, for example, visual information, indicating the area 450 as a successfully isolated safety are within the work site 400. It is also to be noted that the activation of the safety area 450 may be performed by a person who checks the area 450 and then remotely activates a mobile passage control unit outside of its the monitoring volume. It is to be noted that the activation of the safety area 450 may be understood as the isolation of the area becoming operational. Indications such as light and / or sound may be used to indicate that the person is outside of the area 450. This may have a benefit of enabling determining a successfully isolated safety area in an easy manner.

[0057] As mobile passage control units, such as those described above, may be configured to communicate with a positioning unit such as described above, the mobile passage control units may be considered to be capable of determining their location. This may be beneficial as it may make localization of one or more mobile passage control units easier. Additional benefit may be that the one or more mobile passage control units may inform their position to other entities capable of communicating with the one or more mobile passage control units.

[0058] FIG. 5A illustrates a flow chart according to an example embodiment. In this example embodiment, the flow chart illustrates a method for a monitoring system that is configured to monitor a volume of an underground work site. The monitoring system comprises a positioning unit configured to store three-dimensional reference data relating to the monitored volume and at least one mobile passage control unit comprising a sensing device configured to provide three-dimensional sensing data relating to the monitored volume. First, in block SI of the flow chart, the method comprises detecting, by a mobile passage control unit, a triggering event for determining a position of the mobile passage control unit in the underground work site. Then in block S2 the method comprises obtaining, as a response to detecting the triggering event, three-dimensional sensing data relating to the monitored volume by the sensing device. After this in block S3, the method comprises receiving the three-dimensional sensing data by the positioning unit. In block S4, the method comprises determining, by the positioning unit, based on the three-dimensional sensing data and the three-dimensional reference data relating to the monitored volume, the position of the mobile passage control unit. Then in block S5 the method comprises providing, by the positioning unit, information on the position of the mobile passage control unit to the mobile passage control unit, the information on the position comprising a location and orientation of the mobile passage control unit.

[0059] FIG. 5B illustrates another flow chart according to an example embodiment. In this example embodiment, the flow chart illustrates a method for a mobile passage control unit that is suitable for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three- dimensional sensing data relating to the volume. In this example embodiment, in block S6, the method comprises obtaining three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes. In block S7 the method comprises determining, based on the three-dimensional reference data, a set of initially unoccupied sub -volumes within the monitored volume. Then, in block S8, the method comprises obtaining, by the sensing device, three-dimensional sensing data relating to the monitored volume. In block S9 the example embodiment comprises examining obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume. In block S10 the example embodiment comprises detecting, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one sub-volume in the set of initially unoccupied sub-volumes becoming an occupied sub-volume. In block Sil the example embodiment comprises determining, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

[0060] FIG. 5C illustrates a block diagram according to an example embodiment. The units in the block diagram may be understood as logical units the implementation of which may vary in different implementations. The implementation may comprise hardware, software or a combination of both. In this example embodiment, the block diagram illustrates a monitoring system 500 for monitoring an underground work site 550. It is to be noted that the underground work site is a target for the monitoring system 500 and therefore may not be completely part of the monitoring system 500 although some elements comprised in the underground working area 550 may in some example embodiments be comprised in the monitoring system 500. In this example embodiment the monitoring system 500 comprises a positioning unit 520 configured to store three-dimensional reference data relating to the monitored volume. The monitoring system 510 also comprises, in this example embodiment, at least one mobile passage control unit 510 comprising a sensing device 515 configured to provide three-dimensional sensing data relating to the monitored volume. In this example embodiment the monitoring system 500 is configured to detect, by the mobile passage control unit 510, a triggering event for determining a position of the mobile passage control unit 510 in the underground work site. The monitoring system 500 is also configured to obtain, as a response to detecting the triggering event, three-dimensional sensing data relating to the monitored volume by the sensing device 515. The monitoring system 500 is also configured to receive the three-dimensional sensing data by the positioning unit 520. The monitoring system 500 is also configured to determine, by the positioning unit 520, based on the three-dimensional sensing data and the three-dimensional reference data relating to the monitored volume, the position of the mobile passage control unit 510, and provide, by the positioning unit 520, information on the position of the mobile passage control unit 510 to the mobile passage control unit 510, the information on the position comprising a location and orientation of the mobile passage control unit 510.

[0061] FIG. 6 illustrates an example embodiment of an apparatus 600, which may be an apparatus comprised in another device such as a control unit comprised in a monitoring system, in a mobile passage control unit or in a positioning unit. The apparatus 600 comprises a processor 610. The processor 610 is configured to interpret computer program instructions and process data. The processor 610 may comprise one or more programmable processors. The processor 610 may comprise programmable hardware with embedded firmware and may, alternatively or additionally, comprise one or more application specific integrated circuits, ASICs.

[0062] The processor 610 is coupled to a memory 620. The processor is configured to read and write data to and from the memory 620. The memory 620 may comprise one or more memory units. The memory units may be volatile or non-volatile. It is to be noted that in some example embodiments there may be one or more units of nonvolatile memory and one or more units of volatile memory or, alternatively, one or more units of non-volatile memory, or, alternatively, one or more units of volatile memory. Volatile memory may be for example RAM, DRAM or SDRAM. Non-volatile memory may be for example ROM, PROM, EEPROM, flash memory, optical storage or magnetic storage. In general, memories may be referred to as non-transitory computer readable media. The memory 620 stores computer readable instructions that are execute by the processor 610. For example, non-volatile memory stores the computer readable instructions and the processor 610 executes the instructions using volatile memory for temporary storage of data and / or instructions.

[0063] The computer readable instructions may have been pre-stored to the memory 620 or, alternatively or additionally, they may be received, by the apparatus, via electromagnetic carrier signal and / or may be copied from a physical entity such as computer program product. Execution of the computer readable instructions causes the apparatus 600 to perform functionality described above.

[0064] In the context of this document, a "memory” or "computer-readable media” may be any non-transitory media or means that can contain, store, communicate, propagate or transport the instructions for use by or in connection with an instruction execution system, apparatus, or device, such as a computer.

[0065] In an example embodiment, the apparatus is comprised in a mobile passage control unit. The mobile passage control unit in this example embodiment is a mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three- dimensional sensing data relating to the volume, the mobile passage control unit further comprising at least one processor, and at least one memoiy including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the mobile passage control unit to obtain three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes. The at least one memory and the computer program code are also configured, with the at least one processor, to cause the mobile passage control unit to determine, based on the three-dimensional reference data, a set of initially unoccupied sub-volumes within the monitored volume. The at least one memory and the computer program code are also configured, with the at least one processor, to cause the mobile passage control unit to obtain, by the sensing device, three-dimensional sensing data relating to the monitored volume. The at least one memory and the computer program code are configured, with the at least one processor, to cause the mobile passage control unit to examine obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume. The at least one memory and the computer program code are also configured, with the at least one processor, to cause the mobile passage control unit to detect, based on the examining, at least one change event in the set of initially unoccupied sub -volumes, the at least one change event comprising at least one sub -volume in the set of initially unoccupied sub-volumes becoming an occupied sub-volume. The at least one memory and the computer program code are also configured, with the at least one processor, to cause the mobile passage control unit to determine, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

[0066] In an example embodiment, the apparatus is comprised in a mobile passage control unit. The mobile passage control unit in this example embodiment is a mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three- dimensional sensing data relating to the volume, the mobile passage control unit further comprising at least one processor, and at least one memoiy including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the mobile passage control unit to detect, by a mobile passage control unit, a triggering event for determining a position of the mobile passage control unit in the underground work site. The at least one memory and the computer program code are also configured, with the at least one processor, to cause the mobile passage control unit to obtain, as a response to detecting the triggering event, three-dimensional sensing data relating to the monitored volume by the sensing device. The at least one memory and the computer program code are also configured, with the at least one processor, to cause the mobile passage control unit to provide the three-dimensional sensing data to a positioning unit. The at least one memory and the computer program code are also configured, with the at least one processor, to cause the mobile passage control unit to receive, from the positioning unit, information on the position of the mobile passage control unit to the mobile passage control unit, the information on the position comprising a location and orientation of the mobile passage control unit.

[0067] The apparatus 600 optionally further comprises, or is connected to, an input unit 630. The input unit 630 comprises one or more interfaces for receiving input such as a user input or input from another device. The one or more interfaces may comprise for example one or more motion and / or orientation sensors, one or more cameras, one or more accelerometers, one or more microphones, one or more buttons and one or more touch detection units. Further, the input unit 630 may comprise an interface to which external devices may connect to.

[0068] The apparatus 600 also comprises, optionally, an output unit 640. The output unit comprises or is connected to one or more displays capable of rendering visual content. The output unit 640 may further comprise one or more audio outputs. The one or more audio outputs may be for example loudspeakers or a set of headphones.

[0069] The apparatus 600 may further comprise, optionally, a connectivity unit 650. The connectivity unit 650 enables wired and / or wireless connectivity to external networks. The connectivity unit 650 may comprise one or more antennas and one or more receivers that may be integrated to the apparatus 600 or the apparatus 600 may be connected to. The connectivity unit 650 may comprise an integrated circuit or a set of integrated circuits that provide the wireless communication capability for the apparatus 600. Alternatively, the wireless connectivity may be a hardwired application specific integrated circuit, ASIC.

[0070] It is to be noted that the apparatus 600 may further comprise various components not illustrated in the FIG. 6. The various components may be hardware components and / or software components.

[0071] FIG. 7A and FIG. 7B illustrate examples of top views of volumes 704, 706 configured to be monitored by a mobile passage control unit 330 provided onboard a mining machine 702. A perspective view ofvolume 704 of FIG. 7A is illustrated in FIG. 7C. It is however noted that, even if not illustrated in FIG. 7C, monitored volume 704 may comprise a horizontal sub-volume (cf., a roof) configured to enclose a non-monitored volume within the driving surface (e.g., floor of a tunnel) and the monitored volume 704. Monitored volume 704, 706 may therefore comprise a volumetric barrier surrounding or enclosing a non-monitored volume (e.g., a danger area). The danger area may comprise a volume defined by the reach of component(s) or tool(s) of mining machine 702, such as for example boom(s) or drilling unit(s). The volumetric barrier may have a width, which may correspond to at least two voxels. The position of the monitored volume 704, 706 may be defined with respect to the position of mining machine 702, e.g., a reference point thereof.

[0072] The monitored volume 702, 706 maybe configured to be monitored for example with a sensing device (e.g., lidar). It is noted that the sensing device may be configured to capture data also from the non-monitored volume, but the mobile passage control unit 330 may be configured not to monitor objects within the non-monitored volume. The monitored volume 704, 706 may be also referred to as a monitoring zone. Even though particular shapes of monitored volume 704, 706 have been illustrated in FIG. 7A, FIG. 7B, FIG. 7C, monitored volume 704, 706 may be of any arbitrary shape designed specifically for particular application. For example, monitored volume 704, 706 may have any suitable shape, width, depth and height.

[0073] FIG. 7C also illustrates sub-volumes 708 of monitored volume 704. In this example, the twelve illustrated the sub-volumes have rectangular cross-sections, but in general the sub-volumes might be configured to have different shapes. The subvolumes may be configured such that each voxel of monitored volume 704 belongs to at least one sub-volume. Hence, monitored volume 704 might include further subvolumes in addition to those illustrated in FIG. 7C.

[0074] As described above, the mobile passage control unit 330 may be configured to determine that an object is moving or has moved inside monitored volume 704, 706. Configuring the monitored volume as a barrier surrounding a non-monitored volume provides the benefit of enabling free movement (e.g., for boom(s) of mining machine 702) either inside or outside the monitored volume 704, 706. Hence, movement inside or outside the monitored volume 704, 706 may be configured not to cause alarm. However, the mobile passage control unit 330 may be configured to cause an alarm, in response to detecting movement or presence of object(s) in the monitored volume 704, 706, e.g., a particular sub-volume thereof.

[0075] In some example embodiment's), mining vehicle 702 may comprise multiple sensing devices (e.g., lidars), for example at front corners of mining vehicle 702. This may be beneficial because a single sensing device may not be able to monitor the entire volume 704, 706 configured to be monitored. For example, some part(s), e.g., subvolumes, of the monitored volume 704, 706 may not be observable by a single sensing device, for example due to occlusion caused by tool(s) of mining machine, e.g., a drilling unit(s), boom(s), or the carrier of mining machine 702. Therefore, a person might enter the (non-monitored) danger area from behind the boom or drilling unit or from the carrier side without causing an alarm.

[0076] Multiple (e.g., two) sensing devices may be used to remove, or reduce the amount of, blind spots of the monitored volume 704, 706. However, even if using multiple sensing devices it might not be possible to monitor the entire volume 704, 706, because the sensing devices might have common blind spots. The mobile passage control unit 330 may be therefore configured to determine the monitored volume 704, 706 to encompass a blind spot, in response to detecting the sensing devices to have a common blind spot. Mobile passage control unit 330 may be configured to determine the position of the common blind spot based on a union of the blind spots of different sensing devices. Mobile passage control unit 330 may be configured to update the position of the common blind spot based on movement of the boom(s) of mining vehicle 702. The mobile passage control unit 330 maybe configured to cause an indication (e.g., visualization) of determined blind spot(s) and / or common blind spot(s) via the user interface, as will be further described below.

[0077] In some embodiment(s), the monitored volume 704, 706 may be configured to be visualized on a user interface (e.g., graphical user interface such as a display) of mining machine 702 or a remote operator station. The mobile passage control unit 330 may be configured to cause the visualization, for example by controlling rendering of the visualization on the user interface. The visualization of the monitored volume 704, 706 may comprise sub-volume specific status information. The status information may comprise one or more of the following: an indication of a sub-volume comprising a blind spot, an indication of a sub-volume comprising a detected object (e.g., due to a breach of the barrier), or an indication of a sub-volume comprising a permanent structure (e.g., a tunnel wall). The sub-volume specific status information may be indicated for example by rendering sub-volumes associated with different status information by different colours. Visualization of the monitored volume 704, 706 provides the benefit of enabling the user of mining machine 702 to be informed about the configuration of the monitored volume 704, 706 (e.g., location of the monitored volume or locations of the sub-volumes), optionally with the sub-volume specific status information. For example, visually indicating the blind spots improves safety as the user is alerted to pay attention to the blind spots. Visually indicating that an object has entered to monitored volume, or a particular sub-volume thereof, enables the user to be informed about breach of the volumetric barrier, thereby enabling the user for example to take at least some functions of mining machine 702 under manual control.

[0078] In some example embodiment's), the mobile passage control unit 330 may be configured to update the monitored volume 704, 706, in response to a request received via the user interface. For example, the mobile passage control unit 330 may be configured to add more voxels to the monitored volume 704, 706. The mobile passage unit 330 may be configured to add particular voxel(s) in the monitored volume, in response to receiving a request, via the user interface, to add those voxels in the monitored volume 702, 704. This provides the benefit of enabling a user to manually extend the monitored volume 704, 706, for example to close gaps in the original monitored volume. Alternatively, or additionally, the mobile passage control unit 330 may be configured to select one of a plurality of preconfigured volume shapes to be used as the monitored volume 704, 706. The mobile passage control unit 330 may be for example configured with a list of pre-set alternative monitoring volume shapes designed for various situations. This provides the benefit of simplifying configuration of the monitored volume 704, 706.

[0079] In some example embodiments), the mobile passage control unit 330 may be configured to cause the visualization of the monitored volume 704, 706, to include a shape of an object detected within the monitored volume 704, 706. An example of this is illustrated in FIG. 8, where the mobile passage control unit 330 has detected object 802 within the monitored volume 704. In this example, the object has been detected at three sub-volumes 806. Sub-volume(s) including a detected object, or a portion thereof, may be referred to as occupied sub -volume (s). As noted above, the mobile passage control unit 330 may be configured to control the occupied sub- volume(s) to be illustrated with a colour that differs from a colour used to represent unoccupied parts (e.g., sub-volumes) of the monitored volume 704. Illustrating the shape of the detected object provides the benefit of enabling the user of mining machine 702 to determine whether the work can be continued safely (e.g., in case of detecting a dust cloud) or whether the work should be terminated or whether operations of mining machine 702 should be restricted to avoid safety hazards (e.g., in case of detecting a person).

[0080] The mobile passage control unit 330 may be configured to prolong the visualization of the shape of the detected object, for example such that the detected object is visible for a predetermined time period after detecting the object at the monitored volume 704. Alternatively, the mobile passage control unit 330 may be configured to prolong the visualization of the shape of the detected object until receiving, via the user interface, a permission to terminate the visualization of the detected object. It may be generally difficult to remotely diagnose what kind of object caused an alert to trip, because it might not be possible for the user to monitor the system in real-time to see what tripped the system. For example, the object might have disappeared by the time the user gets an alert and checks the visualization. Prolonging the visualization of the detected object provides the benefit of enabling the user to retroactively determine whether operations of mobile mining machine 702 can be safely continued or not. The mobile passage control unit may be configured to disable or restrict operations of mining machine 702, in response to a request from the user interface. The request may for example comprise a request to reset monitoring the volume 704 and / or a request to continue working. The request may be provided remotely, e.g., via a user interface of a remote operator station. Both safety and efficiency of operating mining machine 702 may be therefore improved.

[0081] As used herein, a plurality of items, structural elements, compositional elements, and / or materials maybe presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention.

[0082] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the preceding description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0083] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

Claims

Claims1. A mobile passage control unit configured to monitor a volume of an underground work site comprising an isolated safety area, the mobile passage control unit isolating the isolated safety area, the at least one mobile passage control unit comprising a sensing device configured to provide three-dimensional sensing data relating to the volume, the mobile passage control unit further comprising at least one processor, and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the mobile passage control unit to: obtain three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes; determine, based on the three-dimensional reference data, a set of initially unoccupied sub-volumes within the monitored volume; obtain, by the sensing device, three-dimensional sensing data relating to the monitored volume; examine obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume; detect, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one sub-volume in the set of initially unoccupied sub-volumes becoming an occupied sub -volume; and determine, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

2. A mobile passage control unit according to claim 1, wherein examining the obtained three-dimensional sensing data comprises determining that at least one initially unoccupied sub-volume is associated with three-dimensional sensing data indicative of an object.

3. A mobile passage control unit according to any preceding claim, wherein the at least one criterion relating to the change event comprises duration of occupancy of the occupied sub-volume.

4. A mobile passage control unit according to any preceding claim, wherein the at least one criterion relating to the change event comprises a change event relating to a plurality of adjacent sub-volumes.

5. A mobile passage control unit according to any preceding claim, wherein the three-dimensional reference data comprises a plurality of data frames representing the monitored volume.

6. A mobile passage control unit according to any preceding claim, wherein the at least one memory and the computer program code are further configured, with the at least one processor, to cause the mobile passage unit to communicate with a safety system.

7. A mobile passage control unit according to claim 6, wherein the at least one memory and the computer program code are further configured, with the at least one processor, to cause the mobile passage control unit to provide information relating the object to the safety system.

8. A mobile passage control unit according to any preceding claim, wherein the mobile passage control unit is a battery-operated apparatus.

9. A mobile passage control unit according to any preceding claim, the three-dimensional sensing data comprises a plurality of data frames and the at least one memory and the computer program code are further configured, with the at least one processor, to cause the mobile passage control unit to determine that the object is approaching the mobile passage control unit by comparing the plurality of data frames.

10. A mobile passage control unit according to any preceding claim, wherein the three-dimensional sensing data comprises point cloud data.

11. A mobile passage control unit according to any preceding claim, wherein the three-dimensional sensing is performed using one or more of the following: a multi-layer lidar, a three-dimensional radar, a four-dimensional radar, or ultrasonic sensing.

12. A mobile passage control unit according to any preceding claim, wherein the volume is a subset of a sensed volume, which is a volume that the three- dimensional sensing is capable of sensing.

13. A method for monitoring a volume of an underground work site using a mobile passage control unit comprising a sensing device configured to provide three-dimensional sensing data relating to the volume, the mobile passage control unit further comprising at least one processor, and at least one memory including a computer program code, wherein the at least one memory and the computer program code are configured, with the at least one processor, to cause the mobile passage control unit to perform the method comprising: obtaining three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes; determining, based on the three-dimensional reference data, a set of initially unoccupied sub-volumes within the monitored volume; obtaining, by the sensing device, three-dimensional sensing data relating to the monitored volume; examining obtained three-dimensional sensing data relating to the set of initially unoccupied sub-volumes of the monitored volume; detecting, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one sub-volume in the set of initially unoccupied sub-volumes becoming an occupiedsub -volume; and determining, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

14. A computer program for a mobile passage control unit for monitoring a volume of an underground work site, the mobile passage control unit comprising a sensing device configured to provide three-dimensional sensing data relating to the volume, the mobile passage control unit further comprising at least one processor, and at least one memory including a computer program code, the computer program comprising instructions for causing the mobile passage control unit to perform at least the following: obtain three-dimensional reference data relating to the monitored volume, the volume being defined by a plurality of sub-volumes; determine, based on the three-dimensional reference data, a set of initially unoccupied sub-volumes within the monitored volume; obtain, by the sensing device, three-dimensional sensing data relating to the monitored volume, examine obtained three-dimensional sensing data relating to the set of initially unoccupied sub -volumes of the monitored volume; detect, based on the examining, at least one change event in the set of initially unoccupied sub-volumes, the at least one change event comprising at least one sub -volume in the set of initially unoccupied sub -volumes becoming an occupied sub-volume; and determine, based on the at least one detected change event and at least one criterion relating to the change event, that an object has been moving in the monitored volume.

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