WO2001051930A2

WO2001051930A2 - Snow/debris avalanche detection monitor

Info

Publication number: WO2001051930A2
Application number: PCT/CA2001/000028
Authority: WO
Inventors: Roman Bilak; Laurent Theriault
Original assignee: Mountain Watch Inc.
Priority date: 2000-01-14
Filing date: 2001-01-12
Publication date: 2001-07-19
Also published as: AU2001226603A1; WO2001051930A3; CA2296214A1

Abstract

There is disclosed a portable self-contained apparatus (10) for detecting movement of a displaceable substrate. The apparatus (10) includes a housing (18) adapted to be placed in or on a displaceable substrate. The housing has therein a sensor (24) for sensing movement of the substrate and for generating an output signal upon sensing movement, a transmitter (28) for receiving the output signal and for transmitting a transmission signal, and a power source (22) for supplying power to the apparatus (10).

Description

SNOW/DEBRIS AVALANCHE DETECTION MONITOR

Field of the Invention

The present invention relates to a monitoring means. More particularly, the present invention relates to an apparatus and method for monitoring the shifting or movement of a substrate, which apparatus and method are particularly useful for the detection of potential or actual avalanches, torrents, debris flows, landslides, rock falls or similar events..

Background of the Invention

There is a need for a monitoring or surveillance system which could accurately measure the movement of a substrate in real time to monitor, predict and provide an early warning of mass movements related to avalanches, torrents, debris flows, landslides, rock falls and like potentially catastrophic events.

There are at present a few known avalanche monitoring technologies; however, the majority of such known technologies focus on understanding the avalanche behaviour after actual snow pack failure.

The existing field avalanche monitoring techniques for assessment of snow pack failure or potential snow pack failure include the "Glide Shoe" technique, snow profiling, and snow shear tests.

The "Glide Shoe" technique involves the installation of a series of "glide shoes" along a mountain face between the snow pack and the ground. The glide shoes resemble single-pronged hooks which grip the overlying snow pack and comprise a mobile element that moves with the snow. Each shoe is connected to a rotating potentiometer that comprises a static element fixed to the ground. As the shoe moves with the snow over the ground, a voltage change is registered which can be calibrated to an actual displacement reading. This technique is used for monitoring snow pack movements associated with glide avalanches.

The snow profiling technique involves an experienced individual digging a shallow pit through the entire area of the snow pack, next to the avalanche-prone area. With the section of snow exposed, physical measurements are made of the snow pack layering, snow crystal shapes and sizes, density of layers, hardness of layers, and temperature, every 10 centimeters or so along the section. The data is then evaluated to determine failure potential.

The snow shear test is used in conjunction with the above noted snow profiling technique. A column of snow is isolated so as to be free-standing in a shallow pit. The blade of a shovel or the like is inserted into the various snow layers and then slowly pulled out at a constant force. If the layer is weak, it will fail in shear as the shovel blade is removed. Although this technique is subjective, if the tester is experienced, the test can provide a good indication of the relative shear strengths of the snow pack layers.

Glide shoe, snow pit profiling and snow column testing all use data gathered at one relatively safe location to infer the stability of a much larger and much riskier area that is poised over the actual slide zone. Hence, this data may not be fully representative of the snow pack in the area of instability.

All of the existing techniques suffer from the drawback that they fail to provide real time continuous readings regarding changes occurring in the snow pack prior to and during the occurrence of an avalanche. Further, the existing techniques are labour intensive and require an experienced individual to install, test or profile at the site. Still further, the prior art techniques typically apply subjective, non-quantitative tests. As noted hereinabove, there is a real need for an easily and readily placed remote monitoring or surveillance system which is self-contained and portable and which could accurately measure movement of a snow pack or other substrate in real time to aid in the prediction of a probable avalanche or to warn of an actual avalanche occurring, or other like events. More specifically, there is a need for such a device which could be utilized in the prediction of possible or probable avalanches as well as to warn of potential or occurring torrents, debris flows, landslides, rock falls or the like potentially catastrophic events. Such a device is to be fully autonomous and self-contained without wires, connections or other weak points. At points of deployment, the system of the present invention is operational and user friendly. The apparatus can be deployed over a large area of concern where the initial unstable zones may be ill defined or unknown. As well, in the event of a catastrophic avalanche or debris slide, the devices according to the present invention may be deployed at night or during the day in inclement weather to assist workers in risk assessment. In such circumstances, the devices according to the present invention can indicate whether there is still more substrate that is becoming unstable and whether more snow/debris is moving or not.

Applicants have developed such a monitoring apparatus which is self-powered and contained within a housing which may be easily and remotely placed in a desired position by an individual or by helicopter drop. The monitoring apparatus of the present invention includes a sensor which detects a change in velocity or acceleration of a layer of snow (or other desired substrate) and a transmitter for transmitting a signal based on the movement detected.

Summary of the Invention

In accordance with one embodiment of the present invention there is provided a portable self-contained apparatus for detecting movements of a substrate. The apparatus includes a housing which is adapted to placed in or on a displaceable substrate. The housing has contained therein, a sensor for sensing movement of a substrate and for generating an output signal upon sensing movement. A transmitter is also provided within the housing for receiving the output signal and for transmitting a transmission signal. Additionally, a power source is provided within the housing for supplying power to the apparatus.

In a preferred embodiment there is further provided a first switch for activating the transmitter when an output signal is generated by the sensor. Additionally, a second switch could be provided for deactivating the transmitter when no movement is detected by the sensor or when a predetermined time limit has passed and reset the trigger or first switch for the next movement.

The housing is preferably in the form of a javelin having a hard pointed tip for placement in a displaceable substrate. The power source is preferably located within the tip to weight the same. A preferred power source is at least one battery.

In another preferred form, an analogue comparator or a microprocessor for controlling said transmitter and storing data for transmission is provided. That data could include one or more parameters selected from temperature, time, position and acceleration.

The apparatus of the present invention can be utilized for detecting avalanches, mud slides, debris flows, land slides, rock falls and like mass movements.

Preferably, the sensor utilized within the device is an accelerometer, although any other suitable movement detecting sensor could be utilized such as microphones, tilt sensors or the like. Preferred accelerometers include self exciting magnet coil and piezoelectric sensors or any other suitable accelerometer that senses changes in movement of the substrate such as, but not limited to, capacitive plate and electronic/solid state accelerometers. Preferably, the sensor detects movements which may include a change from one position to a second position; a change from one attitude to a second attitude and a rotation from one angular position to another angular position.

In accordance with another embodiment of the present invention, there is provided a method of detecting movement of a displaceable substrate comprising: positioning at least one portable self-contained apparatus as discussed hereinabove in or on the displaceable substrate; and detecting a transmission signal from the apparatus to indicate a movement of said displaceable substrate.

Brief Description of the Drawings

Having thus generally described the invention, reference will now be made to the accompanying drawings, illustrating preferred embodiments and in which:

Figure 1 is a schematic view of one embodiment of the present invention installed on a mountain face;

Figure 2 is a sectional view of one embodiment of the device;

Figure 3 is a block flow diagram illustrating the components of the device of the present invention;

Figure 4 is a block flow diagram of circuitry/components of a linear controlled device according to the present invention; and

Figure 5 is a block diagram of the circuitry/components of a microprocessor controlled device according to the present invention.

Detailed Description of the Invention

Referring initially at Figure 1, this figure illustrates a schematic view of a plurality of the monitoring devices 10 of the present invention, positioned in a potential avalanche zone 12 of a mountainous area generally designated by reference numeral 14. Reference numeral 16 designates a remote receiver station which may be provided for receiving any signals transmitted by the monitoring device. Alternately, the signals generated by the device 10 may be received by simple receivers such as portable radios which could be carried by individuals in the general area.

An objective of the device 10 of the present invention is to warn as many people as possible that instability is developing within a certain region. Once warned, the interested parties can then commence remedial operations such as event control, evacuation or repairs.

The monitoring device 10 of the present invention could transmit at low power on unused local public broadcast frequencies such that any individual carrying a simple portable radio could listen in and hear the alarm him/herself. This would allow outdoor enthusiasts, such as skiers, who may be crossing a known avalanche runout zone to make a last minute personal assessment of the risk prior to traversing the runout zone.

As illustrated in Figure 2, the device 10 includes a housing 18, preferably in the form of a javelin. The housing 18 can have the shape of a hollow cylindrical tube which can have dimensions in the range of approximately 3.3 mm od and 1.3 meters in length, although obviously any desired shape or size could be utilized. The housing 18 has a pointed tip 20 to aid in penetration into the desired substrate. The other end 21 may be squared or may be tapered for aerodynamics. The device 10 is a self-contained portable device including within the housing 18, a battery or like power source 22, an accelerometer or like sensor 24, a microprocessor or analogue comparator 26 and a transmitter 28. The device is further provided with an antenna 30 at the end 21 of the housing 18.

The batteries 22 are preferably located in the lower end of the device 10 to provide for a weighted tip 20 to aid in the proper positioning of the device 10 within the desired substrate. The batteries 22 could include a protective seal (not shown) to ensure the device 10 has fresh batteries not depleted by storage and transportation.

Once the monitoring device 10 is in place within the desired substrate, the accelerometer 24 will detect any change in velocity (acceleration) of the substrate. The sensor or accelerometer 24 detects an acceleration due to the commencement of movement of the surrounding material (mud, dirt, snow) and generates an electronically loggable electric pulse or signal which is proportional to the magnitude and vector or direction of the acceleration. The signal is caused by a change in velocity with the most dramatic signal being produced from a stationary position (at rest or motionless) to a movement however slight. This includes changes in tilt as that is an "angular" acceleration (rotation about an axis) where the velocity was zero and then accelerated to a new position relative to the original position.

The signal generated by the accelerometer 24 activates the transmitter 28 to emit a, signal which will be detectable with a radio receiver (not shown) either at a remote station 16 or individual receivers carried by individuals. The simplest signal emitted by the transmitter 28 could merely be a short tone signifying an acceleration has been detected which is greater than a specified level. The alternative may be a spoken word message or voice announcement, which may be in several languages, on common broadcast frequencies. Such a voice announcement may specifically state the location and type of activity detected, the risks involved and any suggested action to take as predetermined at the time of deployment of the device by the agency or persons involved in installing the device. On receiving such a message or signal, any affected individuals can make a personnel assessment of risk and conduct themselves accordingly. Depending on the data input, the signal emitted by the transmitter 28 may, however, also contain data such as the magnitude of the acceleration, the direction, the station identification, the location, temperature or any other useful data. Alternatively, if desired, the signal can be encrypted. The sensor or accelerometer 24 may be any suitable type of sensor or accelerometer device which is capable of detecting movement in the context of the present invention. Typically, such sensors or accelerometer devices are those which are activated by a change in motion such as by switching from a state of substantially no relative movement to a state of movement and changing from one position to a second position or by changing from one attitude to a second attitude or rotating from one angular position to another which is a tilt motion..

Various types of devices can be employed for this purpose and which are known per se. Typically, such devices may include geophones, piezoelectric devices, force balance servos, capacitive plate type. By way of example, in the case of a piezoelectric device in the form of a piezoelectric transducer, such a device can be a quartz or similar crystal or film. Both the crystal or the film give off a small charge when strained. As in the moving mass device discussed hereinbelow, the mass tends to resist movement relative to the new motion of the device as buried in the snow pack. The resultant inertia of the mass applies a pressure, or a bending force on the piezoelectric device which results in a strain on the device and thus results in a small electric current being generated. This electric current if sufficient enough in magnitude, will cause the transmitter to transmit the data.

Preferably, the accelerometer is of a type which is known as a self-generating or self energizing accelerometer due to the fact that there are no power requirements prior to activation. Typical such self-energizing types include suspended mass (magnet) in a coil structure. This type of structure operates on the principal that as the mass or magnet moves against suspension springs (and thus moves relative to the enclosing electric coil), the movement of the mass magnet moves the surrounding magnetic field of the magnet in the coils which will induce an electric current. This current will be of sufficient magnitude to activate the other components of the system and effect transmission of the data. By the use of an accelerometer type sensor 24 within the monitoring device 10, it is possible to install the device 10 in a representative area of potential avalanche/debris flow start zones or areas of concern, such as from aerial drops with the use of unskilled labour. The monitoring device 10 once it is lodged in the desired surroundings, and is stable, will basically remain dormant using only the smallest of electrical currents to keep the circuitry charged and ready to detect movement. Until such time as an acceleration or movement is detected, the transmitter 28 is also turned off. At a predetermined magnitude of acceleration the resultant electrical signal activates the circuitry which activates the transmitter 28 and sends out the data.

The monitoring device 10 could include a high frequency cut-off circuit so audible sound (such as aircraft flying overhead) will not cause false alarms. The monitoring device 10 could also include a low frequency cut-off circuit so slow movement of say under a fraction of a cycle per second will not cause false alarms (such as thermal movements from the sun warming the surrounding area as well as the monitoring device 10).

The monitoring device 10 can be inserted into the snow pack or debris field from the safety of a helicopter or from other safe vantage points. Method of insertion is to hurl the javelin shaped device 10 in the same manner as a typical javelin. Just prior to placing the device 10 in a substrate strata, either manually or otherwise, the user would activate the power supply by removing any protective seal, if present, from the batteries 22.

Once inserted into the snow pack/debris field the monitoring device 10 basically remains quiescent. In the event of movement, the acceleration causes the accelerometer 24 to produce a small electric current which, depending on the embodiment, turns on the analogue comparator or microprocessor 26. The microprocessor 26 recognizes the wake up call and either recognizes it as a movement or returns to the quiescent state. If it is a movement, then the microprocessor 26 commences transmitting via a transmitter 28, an announcement that movement has occurred or is occurring at this device location. As well the microprocessor 26 can transmit telemetry data such as temperature, time, position, acceleration and the like. As such, the analogue or microprocessor 26 may incorporate suitable thermometers, timers, sound generators, etc, or such components can be separate components within the overall system.

An avalanche usually starts with a small acceleration then stops, then accelerates/moves again. Alternately, the snow may start moving and accelerate to a full avalanche in a matter of minutes or hours. In either case, the advance warning by the present monitoring device 10 would indicate to individuals or parties that the snow is unstable, i.e. that the movement of the snow is starting and stopping, or an avalanche is underway. If there is a start and stop movement detected by the monitoring device 10, the people concerned may decide not to risk traversing the runout zone. Or if the avalanche is on its way they would have warning that in a few moments a large volume of rapidly moving snow will be filling the runout corridor, depending on the time it takes to descend the distance. In either case, the individuals may wait until the transmissions indicating movements have stopped before safely proceeding.

The transmitter 28 can be any suitable transmitter capable of transmitting a signal; the transmitter 28 can be either a separate component within the overall device 10 or form part of one of the other components of the device 10. For the sake of simplicity, and for economical reasons, the transmitter 28 can be a conventional low powered transmitter such as one capable of broadcasting on an FM band. Depending on the power requirements, and the range of transmission desired, the transmitter 28 will be selected given the appropriate parameters for any given use in the field. Typically, transmitters used in the device 10 of the present invention can be low wattage FM transmitters of e.g. lOOmW, yielding a range of Vz kilometer. The present invention provides an inexpensive, disposable, wireless, self contained device 10 which may be deployed in adverse conditions and in unstable snow/debris fields from the safety of a remote platform such as a helicopter. The device 10 would basically remain inert until there is an acceleration and then would transmit the data and/or signal. The device 10 could also be configured to be launched from launchers, rockets and artillery or the like.

If there are accelerations in the snow/debris field and one or more of the monitoring devices 10 of the present invention are detecting such movement, the transmission of the first device would be joined by other devices in the monitoring area, thus forming a series or plurality of transmissions. If the avalanche or movement is over a large area, in which there are a number of devices 10 of the present invention, the number of transmissions will increase providing a stronger signal and being indicative of the size of the avalanche. If the snow/debris is only settling and hardening there would be only a scattering of transmissions. A wide distribution of devices 10 would give instrumentation over a wide area statistically increasing the likelihood for early detection of movements.

After there is snow/debris movement that stops, the monitoring device 10 of the present invention can still detect new movements until the monitoring device 10 is destroyed. By judicious choice of power source, i.e. batteries 22, the device 10 may be good for 200 events or more before depleting the power source.

After an actual snow/debris avalanche, a new monitoring device 10 according to the present invention may be launched again into the area of concern. Used or old devices may be found in the runout area of the avalanche, and collected for rebuilding or salvage value.

As will be appreciated, the device of the present invention can utilize a microprocessor or alternately, may be a straight analogue/linear based system. Referring now to Fig. 3, illustrating a block diagram of the components and their relationship. A source of power such as batteries 22 are operatively associated with the accelerometer 24 which includes switch means for activating the circuitry upon actuation by the accelerometer 24. An analogue comparator or microprocessor 26 is operatively associated with the accelerometer 24 and generates a data signal or voice signal to the transmitter 28 via circuit 25. Transmitter 28, operatively associated with an antenna 30, will produce the desired transmission to be picked up by a user in the vicinity of the transmission.

Referring to Fig. 4, which illustrates the process control logic of the analogue embodiment, this embodiment is powered by suitable means such as one or more batteries, and utilizes an accelerometer 24 operatively associated with a signal level comparator switch 32. Actuation of accelerometer 24 produces a signal which is effective to activate comparator switch means 32 which in turn activates the power control circuit 34.

In one embodiment, as broadly described above, power control circuit 34 may be associated with a transmitter 28 to provide power to the latter. Transmitter 28 is operative to transmit a signal which may be a voice or data signal through circuitry 36, for receipt by an individual in the vicinity in possession of a suitable receiver. The transmitter 28 may also include a switch circuit 38 to shut down power control and effect reset of the system.

In the embodiment shown in Fig. 4, one alternative feature of the present invention is to include an analog switch circuit 40 operatively associated with the power control circuit 34 which actuates the former upon the accelerometer 24 being actuated. Switch circuit 40 in turn is operatively associated with level switch circuit means 42 which receives a signal from circuit 40 as an input and in conjunction with analog switch circuit 44, provides an analogue comparison readout relative to the signal received from the accelerometer. The analogue switch circuit 44 can function as a comparator circuit to provide minimum comparative levels relative to fixed reference points in order to provide an output signal to an alarm circuit 46. Once the alarm circuit 46 is actuated, it in turn may be operatively associated with the circuitry 36 for voice or data transmission of a signal. The alarm circuit 46 may be separately associated with further switch means 48 effective to turn off power to the apparatus upon termination of the alarm condition.

Turning now to Fig. 5, which illustrates the process control logic for the microprocessor embodiment, similar components to that shown in the Fig. 4 embodiment are provided with similar reference numerals; it will be noted that in Fig. 5, the arrangement of components 24, 32, 34, 28, 36, 38, 46 and 48 is substantially similar to that of Fig. 4. In Fig. 5, however, an analogue input circuit 50 of a microprocessor is operatively associated with the accelerometer 24 and a microprocessor read circuit 52 for receiving the analogue inputs. Operatively associated with circuit 52 is a comparator circuit 54 functioning in a similar manner to that described above with respect to comparator 44 and which is further associated with an alarm circuit 46. In addition to the above, the power control circuit 34 may be operatively associated with a reset and start circuit 56 associated with the microprocessor.

It will be appreciated that a microprocessor based unit will require a suitable microprocessor, which has advantages that the response is programmable and adjustable. It also lends itself to large volumes where downstream programming can be done to make different types of responses for one basic design. In contrast, the analogue design is a relatively simple embodiment.

It will be understood that various modifications can be made to the above described embodiment without departing from the spirit and scope of the invention.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A portable self-contained apparatus (10) for detecting movement of a displaceable substrate, comprising a housing (18) adapted to be placed in or on a displaceable substrate, said housing (18) having therein

(a) sensor means (24) for sensing movement of said substrate and for generating an output signal upon sensing movement;

(b) transmitter means (28) for receiving said output signal and for transmitting a transmission signal; and

(c) a power source (22) for supplying power to said apparatus (10).

2. The apparatus (10) of claim 1 further including first switch means (32) for activating said transmitter means (28) when an output signal is generated by said sensor means (24).

3. The apparatus (10) of claims 1 or 2 further including second switch means (38) for deactivating said transmitter (28) when no movement is detected by said sensor means (24).

4. The apparatus (10) as claimed in claim 1, wherein said housing (18) is in the form of a javelin having a hard pointed tip (20) for placement in said displaceable substrate, said power source (22) being located within said tip (20) to weight the same.

5. The apparatus (10) as claimed in any one of claims 1 to 4, wherein said power source (22) is at least one battery.

6. The apparatus (10) as claimed in any one of claims 1 to 5 further including a member selected from the group consisting of an analogue comparator (26) and a microprocessor (26) for controlling said transmitter (28) and storing data for transmission.

7. The apparatus (10) as claimed in claim 6, wherein said data includes one or more parameters selected from temperature, time, position and acceleration.

8. The apparatus (10) as claimed in any one of claims 1 to 6, wherein the apparatus (10) is for detecting the movement of snow, rock, soils, muds or other such debris.

9. The apparatus (10) as claimed in any one of claims 1 to 8, wherein said sensor (24) is an accelerometer, microphone or tilt sensor.

10. The apparatus (10) as claimed in claim 9, wherein said sensor (24) is an accelerometer.

11. The apparatus (10) as claimed in claim 10, wherein said accelerometer is a magnet coil, piezoelectric, capacitive plate, electronic or solid state accelerometer.

12. The apparatus (10) of any one of claim 1 to 11, wherein said apparatus (10) detects movements selected from the group consisting of a change from one position to a second position; a change from one attitude to a second attitude; and a rotation from one angular position to another angular position.

13. The apparatus (10) according to any one of claims 1 to 12, wherein said apparatus (10) is a self-exciting or self-powering apparatus.

14. Use of the apparatus (10) of any one of claims 1 to 13 for detecting a potential or actual avalanche, debris flow, torrent, rock fall, landslide or mudslide.

15. A method of detecting movement of a displaceable substrate comprising: positioning at least one portable apparatus (10) of any one of claims 1 to 13 in or on said displaceable substrate; and detecting a transmission signal from said apparatus (10) to indicate a movement in said displaceable substrate.