Abstract:
A post-accident network probe and a method of using such a probe are disclosed. The probe is configured to be deployed in a confined environment (e.g. an underground mine), typically after an accident has occurred, in order to establish a connection with the wireless network, or a portion thereof, located therein. The probe generally allows the rescuers to determine the position of potentially trapped miners and can allow the rescuers to have access to environment-related information collected by the network, to get vital signs information, and/or to communicate with the trapped miners. The probe can be deployed using different access methods such as bore holes (existing or new), ventilation shafts, preventive installations of probes, etc. Notably, since the probe establishes a connection with the network, the location of the probe does not have to be exactly where the miners are located as long as the miners are tracked by the network.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    There are no cross-related applications. 
       FIELD OF THE INVENTION 
       [0002]    The present invention generally relates to the field of wireless telecommunication networks and more particularly to the field of telecommunication networks used in confined environments (e.g. underground mines). The present invention also generally relates to the field of mine safety devices, apparatuses and/or systems. 
       BACKGROUND OF THE INVENTION 
       [0003]    Numerous underground mines are developed throughout the world. Though several safety measures are deployed to prevent accident in these mines, accidents such as cave-ins, fires, explosions, and floods do happen. When such an accident happens, the whereabouts of the miners trapped underground become unknown. 
         [0004]    Rescue team may attempt to contact miners by drilling bore holes and dropping a telecommunication line (see for instance U.S. Pat. No. 4,254,994), but unless the trapped miners are in the immediate vicinity of one of the bore holes, these attempts to establish contact with the miners and monitor their conditions will fail and precious time will have been lost. 
         [0005]    In some mines, underground tracking and/or monitoring networks based on a wired backbone are deployed. However, such wired networks do not typically work in many post-accident scenarios because one or more of the cables will have been cut or damaged. Even when tentatively redundant wired networks are deployed, the complexity of continuous network extensions as the mine expands leads to many areas of the mine effectively being not covered with closed loop backbone cables and signal repeaters capable of sending data in both directions. Since fixing broken cables underground from the surface via a bore hole is not realistic, the wired networks often become useless after an accident. 
         [0006]    Another solution to allow communication between the miners, which are located underground, and the rescuers who are located above ground, is Through-The-Earth (“TTE”) technology. One example of a TTE communication system is presented in U.S. Pat. No. 7,043,195. In this example, the system comprises base stations located above ground, repeater stations located underground and mobile stations also located underground. The base stations, repeater stations and mobile stations establish a bi-directional wireless communication path through the ground. However, one drawback with TTE communication systems is that they are very power hungry. Therefore the underground repeater stations typically need to be line-powered. Hence, when an accident occurs, there is a risk that the power lines powering the repeater stations be severed. In addition, the high power consumption generally implies that any portable devices carried by the miners underground must have a large battery. Another drawback with TTE communication systems is that they operate at very low frequencies, therefore requiring very large antennas. Like for the high energy consumption, the large antenna limits the ability to miniaturize the portable devices carried by the miners, which is also a significant inconvenience. Still another drawback of TTE communication systems is that they have a limited range. In other words, depending on the type of ground materials, the depth over which the signals will penetrate can be significantly limited. Hence, for these and other reasons, TTE communication systems are not a functional solution to the problem of communicating with trapped miners after an accident. 
         [0007]    Hence, despite ongoing research in the field, there is still a need for a simple yet functional solution to the problem of communicating with trapped miners after an accident has occurred in an underground mine. 
       SUMMARY OF THE INVENTION 
       [0008]    The shortcomings of the prior art are generally at least mitigated with a post-accident network probe that can be deployed through most bore holes or shafts (hereinafter “bore hole” or “bore holes”) in order to establish a connection with a wireless mesh tracking and/or monitoring network, or at least a portion thereof, located in a confined environment such as an underground mine. 
         [0009]    In accordance with the principles of the present invention, the network probe generally comprises a probe head which is configured, i.e. suitably sized and shaped, to be easily inserted and slid through a bore hole, and which typically comprises all the necessary hardware and software to establish wireless communications with at least one wireless node (fixed or mobile) of the wireless network located underground. The probe head is located at the end of a communication cable which typically provides power to the probe head and a wired communication link between the probe head and a computer system (e.g. a computer, a server, etc.) located above ground. 
         [0010]    Since the network probe is likely to be deployed several hundreds of meters into the ground, the cable is typically reinforced (internally or externally) to support its own weight, including repeater(s) and/or amplifier(s) mounted along its length, and the weight of the probe head. 
         [0011]    When an accident does occur and miners become trapped underground, one or more bore holes will be drilled and the network probe will be deployed into these bore holes. As the probe head reaches a region of the mine where the wireless network is present, the probe head will establish a connection with the wireless network, or at least with a portion of it, if the network has been fractioned by the accident. The connection between the probe head and the wireless network, or portion of it, will provide a new backhaul link to the surface, thereby allowing environment (e.g. 
         [0012]    temperature, gas levels, ground stability, etc.) and personnel information (e.g. locations, vital signs, etc.) collected by the wireless network to be transmitted to the surface and thus to the rescuers. 
         [0013]    Notably, as the network probe establishes a wireless connection with the existing wireless network, or portion thereof, the location of the probe head does not have to be exactly where the trapped miners are located as in previous rescue systems. Indeed, as long as the wireless network, or portion thereof, reached by the network probe covers the area where the trapped miners are located, the exact location of the probe head with respect to the trapped miners is not critical. 
         [0014]    The network probe in accordance with the principles of the present invention therefore generally increases the chances of locating trapped personnel (e.g. miners) in an underground confined environment (e.g. an underground mine). 
         [0015]    Other and further aspects and advantages of the present invention will be obvious upon an understanding of the illustrative embodiments about to be described or will be indicated in the appended claims, and various advantages not referred to herein will occur to one skilled in the art upon employment of the invention in practice. The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The above and other aspects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which: 
           [0017]      FIG. 1  is a fragmentary perspective view of an embodiment of a network probe in accordance with the principles of the present invention. 
           [0018]      FIG. 2  is a perspective exploded view of the network probe of  FIG. 1 . 
           [0019]      FIG. 3  is a schematic view of a portion of an underground mine equipped with a wireless network. 
           [0020]      FIG. 4  is a schematic view of the portion of the underground mine of  FIG. 3 , after an accident has occurred. 
           [0021]      FIG. 5  is a schematic view of the portion of the underground mine of  FIG. 4 , during the deployment of a network probe according to a first exemplary scenario. 
           [0022]      FIG. 6  is a schematic view of the portion of the underground mine of  FIG. 4 , during the deployment of a network probe according to a second exemplary scenario. 
           [0023]      FIG. 7  is a schematic view of the portion of the underground mine of  FIG. 4 , during the deployment of a network probe according to a third exemplary scenario. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0024]    A novel post-accident network probe and methods of using the same will be described hereinafter. Although the invention is described in terms of specific illustrative embodiments, it is to be understood that the embodiments described herein are by way of example only and that the scope of the invention is not intended to be limited thereby. 
         [0025]    Referring first to  FIG. 1 , an embodiment of a network probe  10  in accordance with the principles of the present invention is depicted. 
         [0026]    As it will be best understood below with respect to  FIGS. 3 to 7 , the probe  10  is configured to be lowered into a bore hole made into the ground in order to establish a new backhaul connection with a wireless network, or portion thereof, located into an underground mine, after an accident has occurred, in order to locate possibly trapped miners (or other personnel). 
         [0027]    In that sense, the network probe  10  generally comprises two main components, a probe head  12  and a communication cable  14  connected to the probe head  12  and configured to be connected to a computer system (not shown) located at the surface. 
         [0028]    In the present embodiment, the probe head  12  generally comprises all the necessary wireless networking hardware and software for enabling the probe head  12  to establish proper wireless communications with at least one wireless node (fixed or mobile) of the wireless network located in the underground mine. Understandably, the wireless networking hardware and software of the probe head  12  are configured for the communication protocol used by the underground wireless network. 
         [0029]    In the present embodiment, the wireless networking hardware and software of the probe head  12  are configured for interfacing one wireless communication protocol. Still, in other embodiments, the probe head  12  could comprise several wireless networking hardware and/or software in order for the probe head  12  to be able to communicate with multiple wireless networks using different protocols. 
         [0030]    In the present embodiment, the probe head  12  is configured to communicate with a wireless network of the type comprising battery-powered fixed wireless nodes (“fixed node” or “fixed nodes”) deployed throughout the underground mines in an ad hoc mesh network configuration, and several mobile wireless nodes (“mobile node” or “mobile nodes”) worn by the miners themselves or secured to mobile machinery. An example of such a wireless network is disclosed in International patent application no. PCT/IB2008/002262 (published under no. WO 2009/027816). 
         [0031]    Hence, the probe head  12  essentially comprises the same wireless networking hardware and software as in a fixed node in order for the probe head  12  to be able to communicate both with other fixed nodes and/or with mobile nodes. 
         [0032]    In other embodiments, the probe head  12  could be configured to communicate with a wireless network based on the Zigbee standard (see www.zigbee.org), which is also related to the IEEE 802.15.4 standard, or with a wireless network based on the WiFi Mesh standard (i.e. the IEEE 802.11s standard). 
         [0033]    In still other embodiments, the probe head  12  could be configured to communicate with a wireless network wherein the fixed nodes are line-powered and possibly interconnected with data cables. Such wireless networks would still need to function if some cables are severed or if a portion thereof is isolated after an accident. 
         [0034]    Understandably, the probe head  12 , and more generally the network probe  10 , could be configured to communicate with different types and configurations of wireless networks. 
         [0035]    In the present embodiment, the wireless networking hardware of the probe head  12  generally comprises a processing unit (e.g. central processing unit, a microcontroller, etc.), memory unit(s), a modulating and demodulating (“modem”) unit, and an antenna. 
         [0036]    The probe head  12  also comprises the necessary hardware and software for communicating with the computer system located at the surface and to which the cable  14  is connected. In the present embodiment, the probe head  12  communicates with the computer system located at the surface with a RS-232 or a RS-422 interface and therefore comprises a RS-232 or a RS-422 interface unit. Other interfaces are however possible. 
         [0037]    As illustrated in  FIG. 1 , in the present embodiment, the probe head  12  is preferably elongated and slim in order for the probe head  12  to be easily inserted and slid through a bore hole. 
         [0038]    With additional reference to  FIG. 2 , the mechanical construction of the probe head  12  will now be described. 
         [0039]    The probe head  12  generally comprises a main body  16  which supports the electronic hardware  18  responsible for the wireless communication with the wireless node(s) (fixed and mobile) and for the wired communication with the computer system located as the surface. In the present embodiment, the electronic hardware  18  comprises a main motherboard  20  and a RF module  22  connected thereto. The electronic hardware  18  understandably supports the appropriate software. 
         [0040]    The free extremity  24  of the main body  16 , i.e. the extremity which is not connected to the cable  14 , comprises an antenna connector  26  configured to be connected to the antenna  28 . In the present embodiment, the antenna  28  is mounted into a protective casing  30  which is secured to the main body  16 , typically with appropriate coupling(s) and seal(s) globally referred to at  32  (see  FIG. 2 ). 
         [0041]    The other extremity  34  of the main body  16  is coupled to the cable  14  via a cable coupling  36  and a cable gripping element  38  configured to engage the cable coupling  36 . Various rings and seals generally referred to as  44  can be mounted between the extremity  34 , the coupling  36  and the gripping element  38  to insure that the cable  14  is properly secured to the main body  16 . 
         [0042]    The main body  16  is further mounted into a protective sleeve  40  which is secured thereto via a retaining screw  42 . In  FIG. 1 , the protective sleeve  40  is shown transparently in order to see the internal components of the probe head  12 . However, the protective sleeve  40  is not necessarily transparent. 
         [0043]    Notably, as the probe head  12  is configured to be typically lowered into a bore hole made into the ground, it is most preferable that the material of the casing  30  and of the protective sleeve  40  be strong enough to absorb the numerous impacts and the more or less constant vibration to which the probe head  12  will be subjected during its descent. In the present embodiment, the casing  30  is made of polymeric materials, e.g. 
         [0044]    plastic, and the sleeve  40  is made of metallic materials, e.g. stainless steel. Still, the material(s) of the protective sleeve  40  and more particularly of the casing  30  should not overly interfere with the wireless communication. 
         [0045]    Still referring to  FIGS. 1 and 2 , as it will be best understood below, the cable  14  serves two main purposes. First, it supports the probe head  12  as the probe  10  is lowered into a bore hole. In that sense, the cable  14  is typically reinforced, for example, with metallic (e.g. steel) wires or strands or with polymeric (e.g. Kevlar™) wires or strands. It is to be understood that the probe  10  can be lowered hundreds of meters into the ground in order to reaches deep regions inside the mine. Hence, it is important that the cable  14  can support its own weight, including the weight of the probe head  12  and, if any, the weight of repeaters/amplifiers mounted along the cable  14 . 
         [0046]    Second, the cable  14  provides a wired communication path between the probe head  12  and the computer system located at the surface. Hence, depending on the communication protocol used between the probe head  12  and the computer system, the cable  14  will comprise the appropriate physical communication channel, for instance, a coaxial cable, an optical fiber, a twisted pair of wires, etc. Also, depending on the communication protocol used between the probe head  12  and the computer system, the cable  14  may further comprise power lines in order to provide power to the electronic hardware  18  of the probe head  12 . 
         [0047]    As the probe  10  might be deployed into bore holes hundreds of meters into the ground, repeaters and/or amplifiers (not shown) may be mounted along the length of the cable  14  in order to amplify the signals travelling between the probe head  12  and the computer system. 
         [0048]    In the present embodiment, the cable  14  is a unitary structure which integrates, in a single cable, both the physical communication channel and the reinforcement elements. However, in other embodiments, the cable  14  could be an assembly of a physical communication channel cable (e.g. a coaxial cable, an optical fiber cable) and of one or more reinforcement cables (e.g. a steel cable). In other words, in such embodiments, the reinforcement cable(s) would be external to the communication cable and would be secured thereto. 
         [0049]    In some other embodiments of the network probe  10 , the probe head  12  could further comprise sensors such as gas sensors, heat sensors, humidity sensors, etc. in order to obtain environmental data from the area reached by the probe head  12 , camera(s) and/or microphone(s) in order to obtain visual and/or auditory information about the area reached by the probe head  12 , and/or light(s) and/or speaker(s) to provide visual and/or auditory signals to the trapped miners located in the vicinity of the area reached by the probe head  12 . 
         [0050]    In still some other embodiments of the network probe, the probe head could comprise only the antenna and possibly an amplifier. The cable (e.g. a coaxial cable) would be connected, at its other extremity, to the proper wireless networking hardware which could be distinct of or integrated with the computer system located at the surface. 
         [0051]    Referring now to  FIGS. 3 to 7 , the use and deployment of the network probe  10  will be explained. 
         [0052]    Referring first to  FIG. 3 , a schematic illustration of an underground mine operating under normal conditions is depicted. 
         [0053]    In  FIG. 3 , the mine  100  comprises at least one tunnel or gallery  102  located under a layer of ground (i.e. rock, earth, soil, etc.)  104 . Though only one tunnel  102  is shown, it is to be understood that a typical underground mine  100  comprises a network of such tunnels  102  generally extending over several levels. Hence, the mine  100  shown in  FIG. 3  has been simplified for illustrative purposes only. 
         [0054]    As illustrated, miners  106  and machinery  108  work, operate and/or circulate in the tunnel  102 . 
         [0055]    In the present embodiment, the mine  100  is provided with a wireless network  110  which allows at least the tracking of the miners  106  and of the machinery  108 . The wireless network  110  can also allow the monitoring of the environmental conditions of the mine  100  if appropriate sensors (e.g. air quality sensor, ground stability sensor, etc.) are deployed. Such sensors would be either distinct from the wireless network  110  yet in communication (wired or wireless) with it, or integrated with some of the nodes (fixed or mobile) of the wireless network  110 . 
         [0056]    The wireless network  110  typically comprises a plurality of battery-powered fixed wireless nodes  112 , typically mounted near the ceiling of the tunnel  102 , and a plurality of mobile wireless nodes  114 , typically mounted directly to the machinery  108  or worn by the miners (e.g. in their cap light, on their vest, on their belt, etc.). 
         [0057]    The fixed nodes  112  are configured to communicate wirelessly between each other such as to form an ad hoc mesh network. The fixed nodes  112  are also configured to communicate wirelessly with the mobile nodes  116 , typically for tracking and/or monitoring purposes. 
         [0058]    As illustrated in  FIG. 3 , one of the fixed nodes  112 , referred to as  112 A, is directly connected to a gateway  116  by wires  117 , and the gateway  116  is further connected to a computer system  118  (e.g. a computer, a laptop, a server, etc.) located as the surface via a backhaul cable  119 . The gateway  116  is generally configured to format and transmit the data (e.g. tracking data, monitoring data, environment data, etc.) collected by the fixed nodes  112  to the computer system  118  located at the surface. Normally, an operator monitors the data, which are displayed on the computer system  118 , to make sure that the mine  100  operates normally. 
         [0059]    Referring now to  FIG. 4 , an accident, i.e. a cave-in  120 , occurs within the tunnel  102  and the wireless network  110  is fractioned, i.e. a portion of the network  110  becomes isolated. Indeed, due to the cave-in  120 , the fixed nodes  112  are no longer able to communicate with the fixed node  112 A which is connected to the gateway  116 . However, the isolated fixed nodes  112  are still able to communicate with each other and with the mobile nodes  114  located within their range. 
         [0060]    Referring now to  FIGS. 5 ,  6  and  7 , in accordance with the principles of the present invention, in order to locate the trapped miners  106 , a bore hole  122  is drilled into the ground  104  in order to reach the tunnel  102 . Then, a network probe  10  is lowered into the bore hole  122  until the probe head  12  reaches the tunnel  102 . 
         [0061]    As the probe head  12  reaches the tunnel  102 , it will try to establish a communication with at least one fixed node  112 , typically the nearest, and/or with at least one mobile node  114 . 
         [0062]    If the probe head  12  succeeds in establishing communication with a fixed node  112 , the probe head  12  will be able to retrieve data (e.g. tracking data, monitoring data, environment data, etc.) collected by all the fixed nodes  112  still communicating with each other, and then to forward retrieved data to the surface via the cable  14 . 
         [0063]    If the probe head  12  reaches an area where there are no fixed nodes  112  but where one or more mobile nodes  114  are present, the probe head  12  will establish communication with the one or more mobile nodes  114  within its range, will collect data (e.g. tracking data, monitoring data, etc.) from the one or more mobile nodes  114 , and will transmit the data back to the surface via the cable  14 . 
         [0064]    In any case, as the data reach the surface, rescuers will be able to ascertain whether miners  106  and/or machinery  108  are located in the area reached by the probe head  12 , and will therefore be able to launch rescue efforts in this area if necessary. 
         [0065]    In addition, if sensors are deployed within the mine  100 , the rescuers will be able to determine the environmental conditions of the mine  100  in the area reached by the probe head  12 . Furthermore, depending on the communication capabilities of the wireless network  110 , bi-directional communication (e.g. text messages) between the trapped miners  106  and the rescuers might be possible, thereby allowing further information as to the whereabouts of the trapped miners to be gathered by the rescuers. 
         [0066]    In the scenario of  FIG. 5 , the cable  14  of the probe  10  is connected to a mobile gateway  124  which is connected to a mobile computer system  126  such as a laptop computer. This scenario is likely to occur when the network of tunnels  102  of the mine  100  extends over a wide area and when the tunnel  102  where the accident has happened is far from the operating quarters of the mine  100 . 
         [0067]    In the scenario of  FIG. 6 , the cable  14  is still connected to a mobile gateway  124  but the mobile gateway  124  is connected to the main computer system  118 . This scenario is more likely to occur when the accident happens nearer the operating quarters of the mine  100 , allowing the possibility of a direct connection between the mobile gateway  124  and the main computer system  118 . 
         [0068]    Notably, in both the scenarios of  FIGS. 5 and 6 , the probe head  12  reaches an area where both fixed nodes  112  and mobile nodes  114  are within the communication range of the probe head  12 . Hence, in these two scenarios, the probe head  12  can communicate directly with both the fixed nodes  112  and the mobile nodes  114 . Understandably, these are generally best case scenarios as the probe head  12  directly reaches the trapped miners. 
         [0069]    However, in most scenarios, due to the sheer size of underground mines, the probe head  12  rarely directly reaches the trapped miners. 
         [0070]      FIG. 7  illustrates such a scenario. Indeed, in the scenario of  FIG. 7 , the probe head  12  does not reach an area where mobile nodes  114  are within its direct communication range since the mobile nodes  114  are too far. However, and importantly, the mobile nodes  114  are still in communication with the nearest fixed node  112  and this fixed node  112  is also in communication with the other fixed nodes within the fractioned portion of the wireless network  110 , i.e. the fraction of the wireless network  110  isolated by the cave-in  120 . 
         [0071]    In  FIG. 7 , as the probe head  12  reaches an area where at least one fixed node  112  of the fractioned portion of the wireless network  110  is within its communication range, the probe head  12  will be able to retrieve data (e.g. tracking data, monitoring data, etc.) collected by all the fixed nodes  112  of the fractioned portion of the wireless network  110 , and will thus be able to retrieve the tracking data collected by the fixed node  112  with which the mobile nodes  114  are communicating. 
         [0072]    Hence, in the scenario of  FIG. 7 , even if the probe head  12  does not reach an area where mobile nodes  114  are within its direct communication range, the probe head  12  will still be able to retrieve tracking data regarding these mobiles nodes  114 , and thus regarding the trapped miners  106  (or machinery  108 ) to which these mobile nodes  114  are associated. Consequently, the probe head  12  can retrieve valuable mobile nodes  114  tracking data even if the mobile nodes  114  are not within the direct communication range of the probe head  12 . 
         [0073]    Understandably, the scenarios described above are for the purpose of illustrating how the present embodiment of the network probe  10  is to be deployed and used. Other deployment scenarios, some based on the use of different probes, are understandably possible. 
         [0074]    As the skilled addressee will understand, the network probe in accordance with the principles of the present invention generally allows rescuers to more easily find trapped miners when an accident occurs in an underground mine equipped with a wireless network. In addition, as the network probe in accordance with the principles of the present invention establishes communication with the wireless network (fixed nodes and/or mobile nodes) and not with the miners themselves, the exact location of the probe head with respect to the trapped miners is not critical as long as the wireless network, or the portion thereof, reached by the network probe covers the area where the trapped miners are located. 
         [0075]    Notably, even though the present embodiment of the network probe  10  has been described in the context of underground mines, it is to be understood that a network probe  10 , in accordance with the principles of the present invention, could be used in other contexts where it is necessary to reach confined underground areas or regions. Non-limitative examples of other underground contexts include underground tunnel networks in urban areas (e.g. subway networks, sewer networks, underground maintenance networks, etc.), underground tunnel networks in industrial complexes, underground tunnel networks in civil infrastructures, etc. 
         [0076]    While illustrative and presently preferred embodiments of the invention have been described in detail hereinabove, it is to be understood that the inventive concepts may be otherwise variously embodied and employed and that the appended claims are intended to be construed to include such variations except insofar as limited by the prior art.