Classifications

• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B17/00—Fire alarms; Alarms responsive to explosion
  • G08B17/005—Fire alarms; Alarms responsive to explosion for forest fires, e.g. detecting fires spread over a large or outdoors area
• • G—PHYSICS
  • G08—SIGNALLING
  • G08B—SIGNALLING SYSTEMS, e.g. PERSONAL CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
  • G08B17/00—Fire alarms; Alarms responsive to explosion
  • G08B17/12—Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions
  • G08B17/125—Actuation by presence of radiation or particles, e.g. of infrared radiation or of ions by using a video camera to detect fire or smoke

Definitions

• Fire fighting system mainly conceived to safeguard forests
• the invention presented regards an integrated system which is particularly well suited for the safeguard of wooded areas against fires.
• the scope of this invention is therefore a system which offers automatic monitoring of fires.
• the utilisation of infrared sensors and of all the devices which form the system, are a noteworthy step ahead in the safeguard of wooded areas, till present trusted to towers and look out personnel. But of course the most frequent inconvenience has always been the late arrival of fire fighters due to the fact that there has never been an instantaneous detection of fire and alarm transmission.
• the invention consists of two sub assemblies: the remote detector and the local control centre. More than one detector can be connected to the local control centre, in quantities from 5 to 10. For illustrative non limiting purposes the invention will now be decribed with reference to the tables of drawings attached.
• Figure 1 shows the block diagram of the entire system, where the arrows stand for the connections among the units of the system:
• Peripheral detector (usually each system includes more than one detector); this block is expanded in fiure 2;
• Figure 2 is a schematic representation of the peripheral detector, indicated as block A in figure 1. Here we can see:
• the remote detector consists of:
• An infrared sensor 10 which has a spectral sensitivity such as to provide an optimum detection of hot sources (300-700 degrees C) against an ambient temperature background (0-40 degrees C).
• a spectral sensitivity such as to provide an optimum detection of hot sources (300-700 degrees C) against an ambient temperature background (0-40 degrees C).
• a group of weather sensors 14 which provide data on temperature, relative humidity, pressure, wind speed and direction, solar radiation and rain rate.
• a TV camera 11 for possible visual monitoring of the surveilled area.
• a motor driven platform 12 which confers an azimuth scan to the infrared sensor and to the TV camera over 360 degrees.
• a processor 13 which acquires data from the infrared sensor and provides for extraction of possible alarms, acquires weather sensor data, manages data exchange with the local control centre, from which it receives all commands.
• the infrared sensor data processing is based upon the following procedure: The infrared sensor measures the radiation flow coming from a small angular region, such as 1 degree x 1 degree; the vertical coverage of the sensor is 15 to 20 degrees and is obtained by means of a linear array of sensitive elements. All data coming from a detector is taken into account: in our case taken as an example, there are 360 datum points, one per azimuth degree covered. The number of data may be less if the area to be monitored is only part of a whole
• the processor calculates the value of the derivative of the signal. This provides for the elimination of the signal long term changing effects, on an angle scale of 10 degrees for instance.
• Such variations are typically due to the variation of the angle between the line of sight of the sensor and the position of the sun . On the contrary, point variations are left unchanged, when less or equal to 1 degree, as these are typical signals of fires developing.
• the processor then extracts the mean square value of the fluctuations of the signal subject to derivation for each group of data corresponding to a vertical position which we shall call line .
• Such value is proportional to the fluctuations of the background on the line itself and, multiplied by a suitable constant value, it is taken as a threshold for the detection of possible signals.
• the processor Based upon the threshold determined above, the processor identifies any signal present above such threshold on a line basis. The azimuth angle of the signal is compared with that of signals detected in the previous scans. This is necessary to confer a better reliability to the alarm through a number of consecutive confirmed appearances.
• a communications system 15 such as a radio link remotely controlled by the processor, provides for digital transmission of detected alarms detected by the IR sensor, of weather data and of the TV image to the local control centre.
• the local control centre consists of the following:
• One or more processors with the following functions:
• A Control of the peripheral stations, exchange of commands and data.
• E Recording of data on hard disc or on peripheric units 8 such as tape recorders or optical discs.
• the function provided by the program may be performed during operation of the fire fighting system (called in the following on line functions) or separately (off line).
• the main functions performed by the program are the following:
• Digitising of topographic and thematic maps are the substrate absolutely necessary for the visualization of alarms on the monitor display of the processor and for the development of the forecast algorithms of the fire development.
• Peripheral management This function preferably used off line transports onto paper the graphics displayed on the monitor; this is the documentation required by the fire fighting squads.
• Intervisibility management which is performed between any point of the map and one of the peripheral detection stations. This function is used mostly during setting up of the system and it guides in the selection of the best sighting of the peripheral detectors .
• Forecast of the fire development is based upon the speed and direction of the wind, on ground gradient and type of fuel, resulting in a propagation speed of the fire as a function of absolute azimuth against north.
• the algorithm adopted utilises the following parameters:
• Vfc Variation of the fire propagation speed depending upon the type and humidity of the burning vegetation. Data on the distribution of vegetation is each time read from the data bank.
• - Ci increment constant due to the greater oxygenation due to wind. It is independent of angle with wind direction, but depends on its intensity .
• the program provides a graphic output overlayed on the digitised topographic map showing the successive positions of the fire front edge at pre established time intervals.
• the data which is detected by the infrared sensor 10 are acquired and processed by local processor 13.
• One of the tasks of the processor is also the management of rotating platform 12 onto which the IR sensor and the TV camera 11 are fitted.
• the processor transmits the position of any possible fire together with weather data by means of the communications system 15.
• the TV camera transmits images directly to the local control centre by means of the communications system.
• the data coming from the peripheric detection station 1 is sorted by the communications subsystem 2.
• the TV video is visualized on monitor 6 and can also be recorded 7.
• the infrared sensor data regarding the position of any alarm is fed to processor 3 which places them on the topographic maps.
• the modelling program 4 develops a forecast of the fire evolution in the hours following detections, relying upon historic, weather, vegetation and other data contained in data bank 5.
• the weather data acquired in the last scan are inserted in the data bank.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Business, Economics & Management (AREA)
• Emergency Management (AREA)
• Life Sciences & Earth Sciences (AREA)
• Multimedia (AREA)
• Engineering & Computer Science (AREA)
• Biodiversity & Conservation Biology (AREA)
• Alarm Systems (AREA)
• Fire Alarms (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)
• Fire-Extinguishing Compositions (AREA)
• Fire-Extinguishing By Fire Departments, And Fire-Extinguishing Equipment And Control Thereof (AREA)

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• 1989
  • 1989-12-21 IT IT04868689A patent/IT1237262B/it active IP Right Grant
• 1990
  • 1990-12-19 BR BR909007134A patent/BR9007134A/pt not_active IP Right Cessation
  • 1990-12-19 PT PT96268A patent/PT96268B/pt not_active IP Right Cessation
  • 1990-12-19 WO PCT/EP1990/002244 patent/WO1991009390A1/en not_active Ceased
  • 1990-12-19 AT AT91901284T patent/ATE142039T1/de not_active IP Right Cessation
  • 1990-12-19 EP EP91901284A patent/EP0458938B1/de not_active Expired - Lifetime
  • 1990-12-19 ES ES91901284T patent/ES2094807T3/es not_active Expired - Lifetime
  • 1990-12-19 CA CA002047190A patent/CA2047190C/en not_active Expired - Fee Related
  • 1990-12-19 DE DE69028296T patent/DE69028296T2/de not_active Expired - Fee Related
  • 1990-12-20 TN TNTNSN90156A patent/TNSN90156A1/fr unknown
• 1996
  • 1996-11-07 GR GR960402962T patent/GR3021588T3/el unknown

Non-Patent Citations (1)

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