Method for early detection of a forest fire

Abstract

The invention relates to a method for the early detection of a forest fire using a sensor unit and an evaluation unit, comprising the method steps of detecting sensor signals with the sensor unit, analyzing the signals detected by the sensor unit in a first analysis using a first analysis mode with the evaluation unit, and analyzing the signals detected by the sensor unit in a second analysis using a second analysis mode.

Description

[0001] The invention relates to a method for the early detection of a forest fire using a sensor unit and an evaluation unit with the method steps of detecting sensor signals with the sensor unit, analyzing the signals detected by the sensor unit in a first analysis using a first analysis mode with the evaluation unit and analyzing the signals detected by the sensor unit with a second analysis using a second analysis mode. State of the art

[0002] Systems for the early detection of forest fires are well known. The area to be monitored is monitored using optical sensors that can detect smoke columns resulting from a forest fire. These sensors, for example, take the form of rotatable cameras, but they have the disadvantage of being less effective at night and prone to false detections, e.g., in the case of dust clouds caused by agricultural activities. Furthermore, optical systems can usually only detect forest fires once the forest fire is already advanced and the smoke columns are visible over great distances. Monitoring using an IR camera installed in a satellite from a high orbit has the disadvantage that the resolution of the cameras over great distances prevents detection of forest fires in the early stages. A satellite is also expensive to purchase and maintain, particularly during launch.Surveillance using mini-satellites in low orbit has the disadvantage that the satellites are not geostationary, meaning they require a certain amount of time to orbit the area during which the area is not monitored. Close-meshed surveillance requires a large number of satellites, which are also costly to launch. Surveillance using satellites also results in high carbon dioxide emissions during launch.

[0003] It makes more sense to monitor the area using a number of inexpensive, mass-produced sensors that operate using optical smoke and / or gas detection. The sensors are distributed throughout the area and transmit data to a base station via radio link.

[0004] Such a system for the early detection of forest fires is presented in document US 2008 / 0309502 A1. In the event of a fire alarm, a sensor transmits information to a nearby control terminal, which then triggers an alarm using a long-range radio frequency signal.

[0005] This system has the disadvantage that the control terminal triggers the alarm and requires a powerful RF unit. The sensors require a GPS unit that continuously transmits a signal to the control terminal. Therefore, the sensors consume a lot of power, and the lifespan of the sensors' power sources (batteries) is limited. Task

[0006] It is therefore an object of the present invention to provide a method for the early detection of a forest fire that works reliably, can be expanded as required and is cost-effective to install and maintain.

[0007] The object is achieved by means of the method for the early detection of a forest fire using a sensor unit and an evaluation unit according to claim 1. Advantageous embodiments of the invention are set out in the subclaims.

[0008] The inventive method for the early detection of a forest fire using a sensor unit and an evaluation unit comprises three method steps: In the first method step, sensor signals are recorded using the sensor unit. The sensor unit has a suitable sensor for this purpose, e.g., a temperature and / or gas sensor.

[0009] In the second process step, the signals acquired by the sensor unit are analyzed in a first analysis using a first analysis mode with the evaluation unit. The first analysis of the measurement signal optionally includes converting the measurement signal into first analysis data, which can also be optionally stored and / or transmitted.

[0010] In the third method step, the signals detected by the sensor unit are analyzed using a second analysis mode. The second analysis mode differs from the first analysis mode. Important for the purposes of the invention is the difference in the analysis of the signals detected by the sensor unit using different analysis modes. This increases the reliability and accuracy of the method according to the invention because two independent analysis modes are used for the early detection of a forest fire.

[0011] In a further development of the invention, the detected sensor signals are the signals of a gas. During a forest fire, a number of gases and aerosols are released into the ambient air that are not normally part of the ambient air or are present and detectable only in trace amounts. Such gases include, for example, methane, nitrogen oxides, sulfur dioxide, and carbon monoxide. The detected sensor signals can therefore optionally be from, for example, methane, nitrogen oxides, sulfur dioxide, and carbon monoxide.

[0012] In a further embodiment of the invention, the gas comprises components of the ambient air. Pure, dry air in the near-ground layers of the atmosphere has approximately the following composition of ambient gas components (in vol%): 78% nitrogen, 20.94% oxygen, 0.93% argon, 0.04% carbon dioxide. Other noble gases and components, particularly water vapor, together account for significantly less than 1%. During a forest fire, the ambient air contains a number of foreign gas components that are not common ambient gas components, such as methane, nitrogen oxides, sulfur dioxide, and carbon monoxide.

[0013] In a further embodiment of the invention, the first analysis mode analyzes the detected sensor signals with respect to the air quality of the gas. For the purposes of this document, air quality refers to the qualitative composition of the gas in the ambient air. During a forest fire, the air quality differs from the air quality when a forest fire is not occurring. The first analysis using the first analysis mode analyzes the ambient air for gas components that are not the usual ambient air gas components when a forest fire is not occurring.

[0014] In a further embodiment of the invention, the first analysis mode analyzes the air quality based on the presence of foreign gas components, wherein the foreign gas components differ from the ambient air gas components. The first analysis using the first analysis mode analyzes the ambient air for gas components that are not the usual ambient air gas components when a forest fire is not occurring.

[0015] In a further aspect of the invention, the foreign gas components comprise several gases that are not components of the ambient air. The foreign gas components that are not common ambient air gas components are, for example, methane, nitrogen oxides, sulfur dioxide, and carbon monoxide. These foreign gas components are present in the ambient air, particularly during a forest fire. These foreign gas components are detected and analyzed by a first analysis using the first analysis mode. The presence of these foreign gas components in the ambient air is an indicator of a forest fire.

[0016] In a further embodiment of the invention, the foreign gas components are analyzed in their entirety. The foreign gas components that are not typical ambient air gas components include methane, nitrogen oxides, sulfur dioxide, and carbon monoxide. These foreign gas components are not individually detected and analyzed using the first analysis mode; only the presence of foreign gas components in the ambient air is detected and analyzed.

[0017] In a further embodiment of the invention, the concentration of foreign gas components in the ambient air is analyzed. The foreign gas components are not individually detected and analyzed using the first analysis mode; only the presence of foreign gas components in the ambient air is detected and analyzed. The total concentration of foreign gas components in the ambient air is analyzed using the first analysis mode. An increased total concentration of foreign gas components in the ambient air is an indicator of a forest fire.

[0018] In a further embodiment of the invention, the foreign gas components comprise exclusively gases from a group of predefined gases. These foreign gas components comprise exclusively gases present in the ambient air during a forest fire, e.g., the gases methane, nitrogen oxides, sulfur dioxide, and carbon monoxide.

[0019] In a further development of the invention, the second analysis mode is initiated event-driven. If no event, in particular a forest fire, is detected, no second analysis is performed using the second analysis mode of the detected measurement signal. This minimizes the computational effort.

[0020] In a further embodiment of the invention, the event that initiates the second analysis is based on the results of the first analysis. If the first analysis reveals that an increased total concentration of foreign gas components is present in the ambient air, the second analysis is initiated.

[0021] In a further embodiment of the invention, the second analysis mode is started when the first analysis mode delivers a predefined result. The predefined result of the first analysis mode is, for example, a threshold value for the total concentration of foreign gas components in the ambient air. If this threshold value is exceeded, the second analysis mode is started. This reduces the computing effort and memory requirements of the evaluation unit.

[0022] In an advantageous embodiment of the invention, the second analysis mode analyzes the type of foreign gas components. While the first analysis mode analyzes the total concentration of foreign gas components in the ambient air, the second analysis mode qualitatively analyzes the foreign gas components, i.e., the type of foreign gas components is analyzed. This eliminates the possibility that foreign gas components not generated by a forest fire are indicative of a forest fire.

[0023] In a further aspect of the invention, the second analysis mode analyzes the concentration of the foreign gas components. In addition to the type of foreign gas components, the second analysis mode determines and analyzes the respective concentration of each foreign gas component in the ambient air. This ensures a reliable indication of a forest fire.

[0024] In a further embodiment of the invention, the second analysis mode is performed in the evaluation unit. The second analysis mode is performed using the same evaluation unit as the first analysis mode. Therefore, only one evaluation unit is required to implement the method according to the invention. Power consumption and manufacturing costs of the evaluation unit are therefore reduced.

[0025] In a further embodiment of the invention, the sensor signals are acquired using a first signal acquisition mode and a second signal acquisition mode, with the first signal acquisition mode differing from the second signal acquisition mode. In the first signal acquisition mode, for example, smoke can be detected, while in the second signal acquisition mode, heat can be detected using infrared detection. Important within the meaning of the invention is the difference in signal acquisition using different signal acquisition modes. This increases the reliability and accuracy of the method according to the invention because two independent detection modes are used for the early detection of a forest fire.

[0026] In a further development of the invention, the first signal acquisition is repeated in a first signal acquisition mode of the sensor unit at a time interval. The time interval can be set by a user. For example, one signal acquisition can be performed every second; other time intervals are possible. This allows the temporal resolution of the signal acquisition to be increased or decreased.

[0027] In an advantageous embodiment of the invention, the execution of a second signal acquisition in a second signal acquisition mode of the sensor unit is initiated in an event-driven manner. Such an event can be the failure of a system component of the sensor unit, which prevents signal acquisition in the first mode. Furthermore, signal acquisition can take place in the second signal acquisition mode if an event (fire) was detected by the first signal acquisition. The signals from the first signal acquisition are thus checked, and the method operates more reliably than with signal acquisition in only one signal acquisition mode.

[0028] In a further development of the invention, the second signals acquired by the second signal acquisition mode are evaluated. The signals acquired using the second signal acquisition mode are analyzed and checked to determine whether an event—a fire—has been detected.

[0029] In a further embodiment of the invention, a message is sent from the sensor unit to a first gateway. The message is sent, in particular, when the evaluation of the first signal acquisition and the second signal acquisition has detected a fire. The message is sent as a data packet, either wirelessly or wired, to a first gateway (node).

[0030] In a further embodiment of the invention, the notification signal is generated in the sensor unit when the data from the detected second signals and / or analyzed from these exceeds a second threshold. The threshold can, for example, be the concentration of a gas that is of natural origin or occurs from other sources in the area being monitored by the method according to the invention. If this gas is detected by a second signal detection, the notification is generated and forwarded to a first gateway.

[0031] In a further development of the invention, the second signal acquisition mode comprises a gas analysis. The gas analysis can be performed using suitable gas detectors, e.g., catalytic gas detectors, semiconductor gas detectors, or electrochemical gas detectors. A quantitative analysis can also be performed.

[0032] In a further embodiment of the invention, the first signal acquisition mode is based on a different physical principle than the second signal acquisition mode. The first signal acquisition mode is typically designed for preliminary or rough analysis. A simple, proven, and inexpensive principle can be used for this purpose, e.g., smoke detection using an infrared LED. The second signal acquisition mode serves to increase accuracy and, if necessary, quantitative analysis. Other principles are typically used for this purpose, e.g., electrical ones.

[0033] In a further embodiment of the invention, the first signal detection mode is based on optical smoke detection. The optical chamber of the smoke detector contains an infrared LED and a light-sensitive sensor, a so-called photodiode. The infrared LED continuously emits a test light beam that is invisible to the human eye and is aligned so that it does not directly hit the light-sensitive photodiode. If smoke particles are present in the air and penetrate the optical chamber of the sensor unit, the emitted infrared light beam from the LED is scattered and reflected by the smoke particles. Part of this scattered infrared light also falls on the light-sensitive photodiode.

[0034] In a further development of the invention, the first signal detection mode is based on gas detection. Gas detection can be performed using suitable gas detectors, e.g., catalytic gas detectors, semiconductor gas detectors, or electrochemical gas detectors. Quantitative analysis can optionally be performed.

[0035] Embodiments of the method according to the invention for the early detection of a forest fire using a sensor unit and an evaluation unit are shown in simplified schematic form in the drawings and are explained in more detail in the following description.

[0036] They show: Fig. 1: Basic principle of the procedure for early detection of a forest fire Fig. 2 a: Further development of the procedure for the early detection of a forest fire Fig. 2 b: Further development of the procedure for early detection of a forest fire Fig. 3: Further development of the procedure for early detection of forest fires Fig. 4 a: Sequence diagram of the procedure for early detection of a forest fire, no second analysis Fig. 4 b: Sequence diagram of the early detection procedure for a forest fire, second analysis on a network server Fig. 4 c: Sequence diagram of the process for early detection of a forest fire, second analysis in the terminal, sending a message to the network server

[0037] Fig. Figure 1 shows an embodiment of the method according to the invention for the early detection of a forest fire. In the first method step, sensor signals from the ambient air are recorded by a sensor unit SE. The sensor unit has a gas sensor for this purpose; the sensor signals are therefore sensor signals of a gas. The measurement signals are then analyzed in the evaluation unit using a first analysis mode A1.

[0038] In the first analysis mode (A1), captured SE measurement signals are analyzed for their ambient air components. The first analysis analyzes the ambient air surrounding the sensor unit for foreign gas components. Pure, dry air in the near-ground layers of the atmosphere has approximately the following composition of ambient air gas components (in vol%): 78% nitrogen, 20.94% oxygen, 0.93% argon, 0.04% carbon dioxide. Other noble gases and components, particularly water vapor, together account for significantly less than 1%. This ambient air composition can optionally be supplemented and / or verified by a reference measurement to detect local deviations in the ambient air composition.

[0039] During a forest fire, a variety of gases and aerosols are released into the ambient air that are not normally present in the ambient air or are only present and detectable in trace amounts. These foreign gas components comprise exclusively gases from a group of predefined gases, which in this and all other exemplary embodiments include the gases methane, nitrogen oxides, sulfur dioxide, and carbon monoxide. An increased proportion of these foreign gas components reduces the proportions of the ambient air gas components normally present in the ambient air.

[0040] In the first analysis mode, A1, the quantitative proportion (in vol.%) of the foreign gas components is analyzed together, i.e., the total proportion of foreign gas components in the ambient air is analyzed in the first analysis mode, A1. For this purpose, the proportions of the usual ambient air gas components are recorded and determined.

[0041] In the third process step, the measurement signals are analyzed in the evaluation unit using a second analysis mode, A2. In this second analysis mode, A2, the foreign gas components are qualitatively analyzed, i.e., the type of foreign gas components is recorded. Additionally, in the second analysis mode, A2, the respective concentration of each foreign gas component in the ambient air is determined and analyzed, i.e., the respective concentrations (in vol%) of methane, nitrogen oxides, sulfur dioxide, and carbon monoxide in the ambient air are analyzed.

[0042] Further embodiments of the method according to the invention are shown Fig. 2. In this exemplary embodiment, the second analysis mode A2 is started event-controlled. The sensor unit detects SE sensor signals from the ambient air. In the first analysis mode A1, the detected SE measurement signals are analyzed with regard to the total proportion of foreign gas components in the ambient air. The SE signal detection and its first analysis A1 are carried out continuously ( Fig. 2 a), alternatively, the signal acquisition SE and its first analysis A1 take place at adjustable time intervals t; in this and the other embodiments, t = 1 min. A query is then made as to whether the ambient air contains foreign gas components. Optionally or additionally, a query can be made as to whether the total proportion of foreign gas components in the ambient air exceeds an adjustable threshold.

[0043] If no foreign gas components are present or undetectable in the ambient air, or if the total proportion of foreign gas components in the ambient air is below the threshold, a second analysis is not performed in the second analysis mode A2. Measurement signals from the ambient air continue to be recorded (SE) and analyzed in the first analysis mode A1. If the ambient air contains foreign gas components or if the total proportion of foreign gas components in the ambient air exceeds the threshold, a second analysis is performed in the second analysis mode A2.

[0044] Fig. 3 shows a further embodiment of the method according to the invention, wherein here a second query is carried out after carrying out the second analysis in the second analysis mode A2 and, if necessary, a message VM is sent.

[0045] The sensor unit records SE sensor signals from the ambient air. In the first analysis mode (A1), the recorded SE measurement signals are analyzed. SE signal recording and their initial analysis (A1) occur continuously. A first query then occurs to determine whether the ambient air contains foreign gas components at a concentration that exceeds an adjustable threshold.

[0046] If no foreign gas components are present or undetectable in the ambient air, or if the total proportion of foreign gas components in the ambient air is below the threshold, no second analysis is carried out in the second analysis mode A2; measurement signals from the ambient air continue to be recorded SE and analyzed in the first analysis mode A1. If the ambient air contains foreign gas components or if the total proportion of foreign gas components in the ambient air exceeds the threshold, a second analysis is carried out in the second analysis mode A2. In this second analysis mode A2, the foreign gas components are analyzed qualitatively. In addition, the respective concentration of each foreign gas component in the ambient air is determined and analyzed in the second analysis mode A2.

[0047] After the analysis in the second analysis mode A2, a second query is also performed to determine whether the ambient air contains the foreign gas components methane, nitrogen oxides, sulfur dioxide, and carbon monoxide in a concentration that exceeds a threshold value that can be individually adjusted for each foreign gas component. If the query reveals that the foreign gas components are not present or detectable in the ambient air, no message VM is generated; measurement signals from the ambient air continue to be recorded SE and analyzed in the first analysis mode A1.

[0048] If the query reveals that the concentrations of the foreign gas components methane, nitrogen oxides, sulfur dioxide, and carbon monoxide are higher than the respective threshold values, the evaluation unit generates a VM message. The evaluation unit also generates a VM message if the concentration of just one of the foreign gas components – methane, nitrogen oxides, sulfur dioxide, or carbon monoxide – exceeds the threshold value. The VM message must at least indicate that the sensor unit has detected a forest fire.

[0049] Fig. Figure 4 shows sequence diagrams of the inventive method for the early detection of a forest fire. In this exemplary embodiment, the sensor unit is part of a standard LoRa radio network with its typical star topology. The sensor unit is arranged in a terminal device ED located in the area to be monitored. The terminal device ED is connected via a single-hop connection using LoRa modulation or FSK modulation to a gateway G, which in turn communicates with an internet network server NS using a standard internet protocol.

[0050] Fig. Figure 4a shows the sequence diagram in which the evaluation unit located in the terminal device ED does not detect a forest fire. The sensor unit records SE sensor signals from the ambient air. The recorded SE measurement signals are analyzed in the first analysis mode A1. If no foreign gas components are present or undetectable in the ambient air, or if the total proportion of foreign gas components in the ambient air is below the threshold, the ambient air measurement signals continue to be recorded SE and analyzed in the first analysis mode A1. SE signal recording and the first analysis A1 are performed exclusively on the terminal device ED.

[0051] The second analysis using the second analysis mode A2 can also be performed on the Internet network server NS ( Fig. 4 b). In this exemplary embodiment, SE, the sensor unit arranged in the terminal device ED, detects sensor signals from the ambient air. In the first analysis mode A1, the detected SE measurement signals are analyzed, with the first analysis in the first analysis mode A1 being carried out by an evaluation unit arranged in the terminal device ED. If the ambient air contains foreign gas components or if the total proportion of foreign gas components in the ambient air exceeds the threshold value, the evaluation unit of the terminal device ED generates a message and sends the message to the gateway G. The message contains the information that the terminal device ED has detected that the threshold value of the total proportion of foreign gas components in the ambient air has been exceeded. In addition, the detected SE sensor signals from the sensor unit of the terminal device ED and the result of the first analysis are sent to the gateway G using the first analysis mode A1.The gateway G sends all data received from the terminal device ED to the Internet network server NS. The second analysis is performed on the Internet network server NS using the second analysis mode A2. Signal acquisition SE and the first analysis A1 are performed on the terminal device ED, while the second analysis using the second analysis mode A2 is performed on the Internet network server NS.

[0052] The signal acquisition SE, the first analysis using the first analysis mode A1 and the second analysis using the second analysis mode A2 can also be carried out using an evaluation unit arranged in the terminal ED ( Fig.4 c). The sensor unit records SE sensor signals from the ambient air. The recorded SE measurement signals are analyzed in the first analysis mode (A1). If the ambient air contains foreign gas components or if the total proportion of foreign gas components in the ambient air exceeds the threshold, a second analysis is performed in the second analysis mode (A2), also on the terminal device (ED).

[0053] If the second analysis in the second analysis mode A2 reveals that the foreign gas components are higher in their respective concentrations than the respective threshold values, the evaluation unit generates a message VM. The evaluation unit also generates a message VM if the concentration of just one of the foreign gas components—methane, nitrogen oxides, sulfur dioxide, or carbon monoxide—exceeds the threshold value. This message VM is sent from the terminal device ED to the gateway G, which receives the message VM and sends it to the Internet network server NS. LIST OF REFERENCE SYMBOLS ED device G Gateway NS Internet Network Server SE detection measurement signal A1 First analysis mode A2 Second analysis mode VM Sending a message t time interval QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 2008 / 0309502 A1

[0004]

Claims

[1] Method for the early detection of a forest fire using a sensor unit and an evaluation unit with the following process steps: • Detection (SE) of sensor signals with the sensor unit, • Analyzing the sensor signals recorded by the sensor unit (SE) in a first analysis with a first analysis mode (A1) with the evaluation unit and • Analyzing the sensor signals acquired by the sensor unit in a second analysis using a second analysis mode (A2). [2] Method for the early detection of a forest fire according to claim 1, characterized by that the detected (SE) sensor signals are the sensor signals of a gas. [3] Method for the early detection of a forest fire according to claim 2, characterized by that the gas contains components of the ambient air. [4] Method for the early detection of a forest fire according to one or more of the preceding claims, characterized bythat the first analysis mode (A1) analyses the detected (SE) sensor signals with regard to the air quality of the gas. [5] Method for the early detection of a forest fire according to claim 4, characterized by that the first analysis mode (A1) analyses the air quality based on the presence of foreign gas components, wherein the foreign gas components are different from the ambient air gas components. [6] Method for the early detection of a forest fire according to claim 5, characterized by that the foreign gas components include several gases that are not components of the ambient air. [7] Method for the early detection of a forest fire according to claim 5 or 6, characterized by that the foreign gas components are analyzed in their entirety. [8] Method for the early detection of a forest fire according to one or more of claims 5 to 7, characterized bythat the concentration of foreign gas components in the ambient air is analyzed. [9] Method for the early detection of a forest fire according to one or more of claims 5 to 8, characterized by that the foreign gas components comprise exclusively gases from a group of predefined gases. [10] Method for the early detection of a forest fire according to one or more of the preceding claims, characterized by that the second analysis mode (A2) is started event-controlled. [11] Method for the early detection of a forest fire according to claim 10, characterized by that the event that starts the second analysis (A2) is based on the analysis results of the first analysis (A1). [12] Method for the early detection of a forest fire according to claim 11, characterized by that the second analysis mode (A2) is started when the first analysis mode (A1) delivers a predefined result. [13] Method for the early detection of a forest fire according to one or more of the preceding claims, characterized by that the second analysis mode (A2) analyses the nature of the foreign gas components. [14] Method for the early detection of a forest fire according to one or more of the preceding claims, characterized by that the second analysis mode (A2) analyses the concentration of foreign gas components. [15] Method for the early detection of a forest fire according to one or more of the preceding claims, characterized by that the second analysis mode (A2) is carried out in the evaluation unit.

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