FIRE FIGHTING SYSTEM MAINLY CONCEIVED TO SAFEGUARD FORESTS

Abstract: Fire fighting system mainly conceived for the safeguard of wooded areas, consisting of a number of peripheral detectors (1) each formed by: an infrared sensor (10), a TV camera (11), a rotating platform (12), a local processor (13), a group of weather sensors (14) and a communications subsystem (15). The peripheral sensors refer to a local control centre, which includes the following: peripheral detector (usually more than one detector is included in each system) (1); communications subsystem (2); central processor (3); software modelling for the forecast of monitored fire development (4); historical data base (5); TV monitor (6); video recorder (7); memory unit (hard disc, tape unit) (8); printer (9).

Description: _ Fire fighting system mainly conceived to safeguard forests Description The invention presented regards an integrated system which is particularly well suited for the safeguard of wooded areas against fires. At present, the problem of fires in wooded areas has reached worrying levels. The forests of Argentario and Sardinia are sad evidence of this. 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: 1 Peripheral detector (usually each system includes more than one detector); this block is expanded in fiure 2; 2 Communications subsystem; 3 Central processor; 4 Observed fire evolution prediction model; 5 Historical data base; 6 TV monitor; 7 Video recorder; 8 Memory unit (hard disk, tape unit); 9 Printer. Figure 2 is a schematic representation of the peripheral detector, indicated as block A in figure 1. Here we can see: 10 Infrared sensor; 11 TV camera; 12 Rotating platform; 13 Local processor; 14 Weather sensor group; 15 Communications subsystem. More in detail, 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). As regards operation and structure of such sensor, refer to the invention filed in Italy on December 21, 1989 with number 48685-A/89. 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 round angle. 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. 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. In operation, an alarm is taken as true and therefore transmitted to the local control centre only if it has received a number of confirmations greater than or equal to two in four successive s c an s It is to be noted that this procedure may be completed by the peripheral detection unit in about three minutes, therefore reducing the present detection times of a fire in wooded areas quite considerably. 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. At the local control centre, the transmitted data is sent to units which perform their processing, registration and integration with data available in cartographic, thematic and historical archives. The local control centre consists of the following: A TV monitor 6 and a video recorder 7 for the viewing and possible recording of the TV images coming from the remote detection centres. One or more processors with the following functions: A: Control of the peripheral stations, exchange of commands and data. B: Visualization of alarms, notified by the peripheral detection stations, on topographic maps of the area by means of three dimensional projection; calculation of possible intersections between alarms coming from different peripheral stations so as to assure an even more accurate location. C: Integration of alarms with instantaneous weather data, with data banks containing information on the distribution of vegetation, on recent weather conditions and on human presence in the area . D: Following integration of data and as a function of it, a fire propagation model is developed; such model is described later on in detail and it is one of the most innovative points of this invention . E: Recording of data on hard disc or on peripheric units 8 such as tape recorders or optical discs. F: System status display including possible alarm messages on printer 9. We shall now describe briefly the procedure adopted for the forecast of the evolution of the observed fire. 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. The data which is available from this digitising 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. The model 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: - Vfo = Intrinsic average speed of propagation of the fire. 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. SUBSTITUTE SHEET The effect of wind is quantified by the following parameters which have an effect on the propagation speed: - Ci = increment constant due to the greater oxygenation due to wind. It is independent of angle with wind direction, but depends on its intensity . - Ct = transport constant of the fire front edge, which depends upon the angle between the propagation line and wind direction. 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. Now we shall proceed with the detailed description of system operation, with illustrative non limiting purposes, making reference to the two figures mentioned above. At the peripheral detection site (Figure 2), 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. Following interrogation of weather station 14, 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. All alarms are processed on the system monitor, on printer 9 and possibly recorded on mass memory 8.

Claims: Claims 1. Fire fighting system, mainly conceived for the safeguard of wooded areas, consisting of the following: Peripheral detection station (generally there are more than one station for each system shown in figure 2) (1); - Communications subsystem (2); - Central processor (3); - Model for the forecast of the evolution of the observed fire (4); - Data base with historic data (5); - TV monitor (6) ; - Videorecorder (7); - Memory unit (hard disk, tape unit) (8); - Printer (9). 2. Fire fighting system mainly conceived for the safeguard of wooded areas, where the detection station 1 in Figure 1, consists of the following: - Infrared sensor (10); - T camera ( 11) ; - Rotating platform (12); - Local processor (13); - Weather sensor group (14); - Peripheral station communication subsystem (15). - 1 2 - 3. Fire fighting system mainly conceived for the safeguard o wooded areas, where the infrared sensor of the peripheral statio is made in accordance with the invention filed in Italy o December 21, 1989 with the Number 48685-A/89. 4. Fire fighting system mainly conceived for the safeguard o wooded areas where the infrared signal detected by sensor (10) reaches a processor which by means of a suitable progra discriminates the signals coming from hot sources. 5. Fire fighting system, mainly conceived for the safeguard o wooded areas, where the prediction model provides a result whic derives from the integration of the position of the signal detected with the weather data acquired in real time, wit historical weather data and with the site cartographi characteristics.

Inventors: BROGI GIULIO, FRAU FRANCESCO, PIETRANERA LUCA, BROGI, GIULIO, FRAU, FRANCESCO, PIETRANERA, LUCA
Applicants: SELENIA IND ELETTRONICHE, SELENIA INDUSTRIE ELETTRONICHE ASSOCIATE S.P.A.
Application year: 1990
Main classification: G08B17
IPC codes: G08B17