SE1300768A1 - System and method for detecting motion in bedrock - Google Patents

System and method for detecting motion in bedrock Download PDF

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Publication number
SE1300768A1
SE1300768A1 SE1300768A SE1300768A SE1300768A1 SE 1300768 A1 SE1300768 A1 SE 1300768A1 SE 1300768 A SE1300768 A SE 1300768A SE 1300768 A SE1300768 A SE 1300768A SE 1300768 A1 SE1300768 A1 SE 1300768A1
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Sweden
Prior art keywords
signal
rock
detection system
location
movement detection
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SE1300768A
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Swedish (sv)
Inventor
Elina Vartiainen
Johan Sjoeberg
Petra Bjoerndal
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Abb Research Ltd
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Priority to SE1300768A priority Critical patent/SE1300768A1/en
Publication of SE1300768A1 publication Critical patent/SE1300768A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01V—GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS
    • G01V3/00—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation
    • G01V3/18—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging
    • G01V3/26—Electric or magnetic prospecting or detecting; Measuring magnetic field characteristics of the earth, e.g. declination, deviation specially adapted for well-logging operating with magnetic or electric fields produced or modified either by the surrounding earth formation or by the detecting device

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Remote Sensing (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Electromagnetism (AREA)
  • Environmental & Geological Engineering (AREA)
  • Geology (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Geophysics (AREA)
  • Emergency Alarm Devices (AREA)

Abstract

A rock movement detection system (10) comprises a transmitter (20) attached to rock at a first location and configured to transmit a wireless signal, a receiver (30) attached to rock at a second location and configured to receive the signal, a signal analyser configured to deduce from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant, and a processor configured to calculate an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter.(Figure 1)

Description

10 15 20 25 30 These objects are achieved by the device according to appended claim 1 and the method according to appended claim 13. 10 15 20 25 30 These objects are achieved by the device according to appended claim 1 and the method according to appended claim 13.

The invention is based on the realization that different parameters of wireless signals can be used to automatically measure distances between predefined reference points at mine locations.The invention is based on the realization that different parameters of wireless signals can be used to automatically measure distances between predefined reference points at my locations.

According to a first aspect of the invention, there is provided a rock movement detection system comprising: a transmitter attached to rock at a first location and configured to transmit a wireless signal, a receiver attached to rock at a second location and configured to receive the signal. A signal analyser is configured to deduce from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant. A processor is configured to calculate an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter. By basing a distant measurement between reference points within a mine on wireless signal parameters, eventual changes in the distances can be detected by means of an automated system.According to a first aspect of the invention, there is provided a rock movement detection system comprising: a transmitter attached to rock at a first location and configured to transmit a wireless signal, a receiver attached to rock at a second location and configured to receive the signal. A signal analyzer is configured to deduce from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant. A processor is configured to calculate an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter. By basing a distant measurement between reference points within a mine on wireless signal parameters, eventual changes in the distances can be detected by means of an automated system.

According to one embodiment of the invention the signal comprises an acoustic or an electromagnetic wave.According to one embodiment of the invention the signal comprises an acoustic or an electromagnetic wave.

According to one embodiment of the invention the signal comprises a radio signal such as a WiFi signal, an UWB signal or a Bluetooth signal.According to one embodiment of the invention the signal comprises a radio signal such as a WiFi signal, an UWB signal or a Bluetooth signal.

According to one embodiment of the invention the signal comprises a magnetic field.According to one embodiment of the invention the signal comprises a magnetic field.

According to one embodiment of the invention the transmitter is furthermore configured to receive a wireless signal, and 10 15 20 25 30 the receiver is furthermore configured to transmit a wireless signal.According to one embodiment of the invention the transmitter is furthermore configured to receive a wireless signal, and 10 15 20 25 30 the receiver is furthermore configured to transmit a wireless signal.

According to one embodiment of the invention the system comprises a plurality of transmitters and/or receivers attached to rock at a respective plurality of locations.According to one embodiment of the invention the system comprises a plurality of transmitters and / or receivers attached to rock at a respective plurality of locations.

According to one embodiment of the invention the signal analyser is further configured to deduce values of additional signal parameters, and the processor is further configured to calculate the eventual change in the distance on the basis of the values of the additional signal parameters.According to one embodiment of the invention the signal analyzer is further configured to deduce values of additional signal parameters, and the processor is further configured to calculate the eventual change in the distance on the basis of the values of the additional signal parameters.

According to one embodiment of the invention the first signal parameter or any of the additional signal parameters relate to signal strength.According to one embodiment of the invention the first signal parameter or any of the additional signal parameters relate to signal strength.

According to one embodiment of the invention the first signal parameter or any of the additional signal parameters relate to the time the signal needs to travel between the first and the second locations.According to one embodiment of the invention the first signal parameter or any of the additional signal parameters relate to the time the signal needs to travel between the first and the second locations.

According to one embodiment of the invention the rock movement detection system furthermore comprises a feedback device for informing an operator about the eventual change in the distance.According to one embodiment of the invention the rock movement detection system furthermore comprises a feedback device for informing an operator about the eventual change in the distance.

According to one embodiment of the invention the rock movement detection system furthermore comprises an alarm device triggering an alarm when the eventual change in the distance exceeds a predetermined threshold value.According to one embodiment of the invention the rock movement detection system furthermore comprises an alarm device triggering an alarm when the eventual change in the distance exceeds a predetermined threshold value.

According to one embodiment of the invention an underground mine comprises a rock movement detection system according to the description hereinbefore.According to one embodiment of the invention an underground mine comprises a rock movement detection system according to the description hereinbefore.

According to a second aspect of the invention, there is provided a method for detecting rock movement. The method 10 15 20 25 30 comprises the steps of: transmitting a wireless signal from a transmitter attached to rock at a first location; receiving the signal with a receiver attached to rock at a second location; deducing from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant; and calculating an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter.According to a second aspect of the invention, there is provided a method for detecting rock movement. The method 10 15 20 25 30 comprises the steps of: transmitting a wireless signal from a transmitter attached to rock at a first location; receiving the signal with a receiver attached to rock at a second location; deducing from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant; and calculating an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be explained in greater detail with reference to the accompanying figure 1 showing one embodiment of the invention.LETTER DESCRIPTION OF THE DRAWINGS The invention will be explained in greater detail with reference to the accompanying figure 1 showing one embodiment of the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS Referring to figure 1, an illustration of an underground mine comprising a rock movement detection system 10 according to one embodiment of the invention is shown. The system 10 comprises a wireless router 20 transmitting and receiving WiFi signals at a first location which is considered to lie at a stable part of the mine and to be non~movable. The router 20 is fixedly attached to a bore hole in a mine wall. The router 20 is connected with a network cable to an internal network of the mine, and further to internet. The router 20 is thereby also used for other purposes than for detecting rock movement, in this case it provides a wireless network access within the mine.DESCRIPTION OF PREFERRED EMBODIMENTS Referring to figure 1, an illustration of an underground mine comprising a rock movement detection system 10 according to one embodiment of the invention is shown. The system 10 comprises a wireless router 20 transmitting and receiving WiFi signals at a first location which is considered to lie at a stable part of the mine and to be non ~ movable. The router 20 is fixedly attached to a bore hole in a mine wall. The router 20 is connected with a network cable to an internal network of the mine, and further to internet. The router 20 is thereby also used for other purposes than for detecting rock movement, in this case it provides a wireless network access within the mine.

Four transceivers 30 are fixedly attached to bore holes in the mine wall at four different locations. Each transceiver 30 comprises a voltage source, a clock, a signal generator and an antenna. The transceivers 30 send WiFi signals at a constant signal strength in response to forward signals received from the router 20. A return signal is sent after a 10 15 20 25 30 35 constant time delay after receiving a forward signal. The router 20 is connected to a signal analyser that records the received return signals, and is able to measure from the signals an average signal strength. The router 20 repeats the sending and receiving of signals at certain intervals, for example once every minute, and the values of the average signal strengths are stored on a computer memory and compared with those from the previous measurements. A change in signal strength indicates a change in the distance between the router 20 and the respective transceiver 30.Four transceivers 30 are fixedly attached to bore holes in the mine wall at four different locations. Each transceiver 30 comprises a voltage source, a clock, a signal generator and an antenna. The transceivers 30 send WiFi signals at a constant signal strength in response to forward signals received from the router 20. A return signal is sent after a 10 15 20 25 30 35 constant time delay after receiving a forward signal. The router 20 is connected to a signal analyzer that records the received return signals, and is able to measure from the signals an average signal strength. The router 20 repeats the sending and receiving of signals at certain intervals, for example once every minute, and the values of the average signal strengths are stored on a computer memory and compared with those from the previous measurements. A change in signal strength indicates a change in the distance between the router 20 and the respective transceiver 30.

Alternatively, a change in the distance between the router 20 and the respective transceiver 30 can be detected by comparing the times needed for the signal to travel between them at different measurement instances.Alternatively, a change in the distance between the router 20 and the respective transceiver 30 can be detected by comparing the times needed for the signal to travel between them at different measurement instances.

Although a single router 20 is sufficient for detecting certain relative movements of the transceivers 30, the measurements give little information about the absolute positions of the transceivers. Moreover, movements of a transceiver 30 in tangential directions in relation to the router 20 go undetected. Therefore, the rock movement detection system 10 preferably comprises three of more routers 20. The use of a plurality of routers 20 also enables the use of time-difference-of-arrival for detecting a change in the distance between a certain router 20 and a respective transceiver 30.Although a single router 20 is sufficient for detecting certain relative movements of the transceivers 30, the measurements give little information about the absolute positions of the transceivers. Moreover, movements of a transceiver 30 in tangential directions in relation to the router 20 go undetected. Therefore, the rock movement detection system 10 preferably comprises three of more routers 20. The use of a plurality of routers 20 also enables the use of time-difference-of-arrival for detecting a change in the distance between a certain router 20 and a respective transceiver 30.

A computer storing the measurement results is preferably situated at a control room distant from the measurement locations. The computer is running a mine surveillance application monitoring and illustrating distances between the router 20 and the different measurement locations. When a change in a distance is detected, the change is illustrated on a computer screen in a corresponding manner as shown in figure l. An operator can thereby monitor eventual changes in the distances comfortably from the control room. A critical threshold value for the change in 10 15 20 25 30 35 each distance can be defined in advance. When the corresponding threshold value is exceeded, the mine surveillance application generates an alarm for informing the operator about a critical rock movement.A computer storing the measurement results is preferably situated at a control room distant from the measurement locations. The computer is running a mine surveillance application monitoring and illustrating distances between the router 20 and the different measurement locations. When a change in a distance is detected, the change is illustrated on a computer screen in a corresponding manner as shown in figure 1. An operator can thereby monitor eventual changes in the distances comfortably from the control room. A critical threshold value for the change in 10 15 20 25 30 35 each distance can be defined in advance. When the corresponding threshold value is exceeded, the mine surveillance application generates an alarm for informing the operator about a critical rock movement.

Alternatively, a rock movement detection system 10 according to the invention may consist of only one transmitter 20 at a first location and one receiver 30 at a second location constituting a local warning system within the mine. The receiver 30 may comprise a signal analyser for deducing from a signal sent by the transmitter 20 a signal parameter of interest, such as signal strength. The receiver 30 may further comprise computing means for calculating an eventual change in a distance between the first location and the second location on the basis of signal strengths at the second location at two instances. The receiver 30 may yet further comprise warning means, such as a warning lamp, for warning mine workers when the eventual change in the distance exceeds a predetermined threshold value.Alternatively, a rock movement detection system 10 according to the invention may consist of only one transmitter 20 at a first location and one receiver 30 at a second location constituting a local warning system within the mine. The receiver 30 may comprise a signal analyzer for deducing from a signal sent by the transmitter 20 a signal parameter of interest, such as signal strength. The receiver 30 may further comprise computing means for calculating an eventual change in a distance between the first location and the second location on the basis of signal strengths at the second location at two instances. The receiver 30 may yet further comprise warning means, such as a warning lamp, for warning mine workers when the eventual change in the distance exceeds a predetermined threshold value.

Instead of WiFi signals, the wireless signal may consist of a constant magnetic field generated at a first location. A magnetic field density is measured at a second location, and an eventual change in a distance between the first location and the second location is calculated on the basis of magnetic field densities at the second location at two instances. The calculation can be based on a theoretical model on how the magnetic field density changes as the function of distance. Alternatively, the mine environment can be measured to create a fingerprint of the magnetic density at different locations of the mine. If such fingerprint is available, it can be used for the calculation of the eventual change in the distance between the first location and the second location instead of the theoretical model. When WiFi signals are used, a corresponding fingerprint can be measured for WiFi signal environment within the mine.Instead of WiFi signals, the wireless signal may consist of a constant magnetic field generated at a first location. A magnetic field density is measured at a second location, and an eventual change in a distance between the first location and the second location is calculated on the basis of magnetic field densities at the second location at two instances. The calculation can be based on a theoretical model on how the magnetic field density changes as the function of distance. Alternatively, the mine environment can be measured to create a fingerprint of the magnetic density at different locations of the mine. If such fingerprint is available, it can be used for the calculation of the eventual change in the distance between the first location and the second location instead of the theoretical model. When WiFi signals are used, a corresponding fingerprint can be measured for WiFi signal environment within the mine.

The invention is not limited to the embodiments shown above, but the person skilled in the art may modify them in a plurality of ways within the scope of the invention as defined by the claims. For example, instead of WiFi signals or a magnetic field, the wireless signal may comprise other radio signals or even an acoustic signal.The invention is not limited to the embodiments shown above, but the person skilled in the art may modify them in a plurality of ways within the scope of the invention as defined by the claims. For example, instead of WiFi signals or a magnetic field, the wireless signal may comprise other radio signals or even an acoustic signal.

Claims (1)

10 15 20 25 30 CLAIMS 1. A rock movement detection system (10) comprising: a transmitter (20) attached to rock at a first location and configured to transmit a wireless signal, a receiver (30) attached to rock at a second location and configured to receive the signal, a signal analyser configured to deduce from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant, and a processor configured to calculate an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter. A rock movement detection system (10) according to claim 1, wherein the signal comprises an acoustic or an electromagnetic wave. A rock movement detection system (10) according to any of the preceding claims, wherein the signal comprises a radio signal such as a WiFi signal, an UWB signal or a Bluetooth signal. A rock movement detection system (10) according to any of the preceding claims, wherein the signal comprises a magnetic field. A rock movement detection system (10) according to any of the preceding claims, wherein the transmitter (20) is furthermore configured to receive a wireless signal, and (30) a wireless signal. the receiver is furthermore configured to transmit A rock movement detection system (10) according to any of the preceding claims, wherein the system (10) comprises a plurality of transmitters (20) and/or 10 15 20 25 30 10. 11. 12. 13. receivers (30) attached to rock at a respective plurality of locations. A rock movement detection system (10) according to any of the preceding claims, wherein the signal analyser is further configured to deduce values of additional signal parameters, and the processor is further configured to calculate the eventual change in the distance on the basis of the values of the additional signal parameters. A rock movement detection system (10) according to any of the preceding claims, wherein the first signal parameter or any of the additional signal parameters relate to signal strength. A rock movement detection system (10) according to any of the preceding claims, wherein the first signal parameter or any of the additional signal parameters relate to the time the signal needs to travel between the first and the second locations. A rock movement detection system (10) according to any of the preceding claims, furthermore comprising a feedback device for informing an operator about the eventual change in the distance. A rock movement detection system (10) according to any of the preceding claims, furthermore comprising an alarm device triggering an alarm when the eventual change in the distance exceeds a predetermined threshold value. An underground mine comprising a rock movement detection system (10) according to any of the preceding claims. A method for detecting rock movement, the method comprising the steps of: - transmitting a wireless signal from a transmitter (20) attached to rock at a first location; - receiving the signal with a receiver (30) attached to 10 14. 10 rock at a second location; - deducing from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant; and - calculating an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter. A method according to claim 13, further comprising the step of: - deducing values of additional signal parameters, and calculating the eventual change in the distance on the basis of the values of the additional signal parameters.10 15 20 25 30 CLAIMS 1. A rock movement detection system (10) comprising: a transmitter (20) attached to rock at a first location and configured to transmit a wireless signal, a receiver (30) attached to rock at a second location and configured to receive the signal, a signal analyzer configured to deduce from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant, and a processor configured to calculate an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter. A rock movement detection system (10) according to claim 1, wherein the signal comprises an acoustic or an electromagnetic wave. A rock movement detection system (10) according to any of the preceding claims, wherein the signal comprises a radio signal such as a WiFi signal, an UWB signal or a Bluetooth signal. A rock movement detection system (10) according to any of the preceding claims, wherein the signal comprises a magnetic field. A rock movement detection system (10) according to any of the preceding claims, wherein the transmitter (20) is further configured to receive a wireless signal, and (30) a wireless signal. the receiver is furthermore configured to transmit A rock movement detection system (10) according to any of the preceding claims, wherein the system (10) comprises a plurality of transmitters (20) and / or 10 15 20 25 30 10. 11. 12 13. receivers (30) attached to rock at a respective plurality of locations. A rock movement detection system (10) according to any of the preceding claims, wherein the signal analyzer is further configured to deduce values of additional signal parameters, and the processor is further configured to calculate the eventual change in the distance on the basis of the values of the additional signal parameters. A rock movement detection system (10) according to any of the preceding claims, wherein the first signal parameter or any of the additional signal parameters relate to signal strength. A rock movement detection system (10) according to any of the preceding claims, wherein the first signal parameter or any of the additional signal parameters relate to the time the signal needs to travel between the first and the second locations. A rock movement detection system (10) according to any of the preceding claims, furthermore comprising a feedback device for informing an operator about the possible change in the distance. A rock movement detection system (10) according to any of the preceding claims, furthermore comprising an alarm device triggering an alarm when the eventual change in the distance exceeds a predetermined threshold value. An underground mine comprising a rock movement detection system (10) according to any of the preceding claims. A method for detecting rock movement, the method comprising the steps of: - transmitting a wireless signal from a transmitter (20) attached to rock at a first location; - receiving the signal with a receiver (30) attached to 10 14. 10 rock at a second location; - deducing from the signal a first value of a first signal parameter at a first instant, and a second value of the first signal parameter at a second instant; and - calculating an eventual change in a distance between the first location and the second location on the basis of the first and the second values of the first signal parameter. A method according to claim 13, further comprising the step of: - deducing values of additional signal parameters, and calculating the eventual change in the distance on the basis of the values of the additional signal parameters.
SE1300768A 2013-12-12 2013-12-12 System and method for detecting motion in bedrock SE1300768A1 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023204741A1 (en) * 2022-04-22 2023-10-26 Telefonaktiebolaget Lm Ericsson (Publ) Method and apparatus for detecting falling objects via a wireless communication network

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2023204741A1 (en) * 2022-04-22 2023-10-26 Telefonaktiebolaget Lm Ericsson (Publ) Method and apparatus for detecting falling objects via a wireless communication network

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