System and Method for Monitoring an Airspace of an Extended Area

Abstract

The invention relates to a system for monitoring an airspace for an extensive area, with at least two optical sensors with a passive Fourier transform infrared spectrometer, wherein each optical sensor has an adjustable monitoring range and wherein the monitoring ranges of the at least two optical sensors overlap at least in sections, having a server for evaluating the measurement data and for controlling the at least two optical sensors, the server being set up to monitor the optical sensors for automatic scanning of the monitored areas, wherein the server assigns a respective solid angle to the measurement data on the basis of the position data of the optical sensor, evaluates the measurement data of the optical sensors to derive the spectral intensity distribution of the received IR radiation for each solid angle and, by means of correlation of the intensity distribution with known gas spectra, to identify at least one target substance, in the event of an incident, if a first optical sensor identifies a target substance in a first solid angle, to control at least one further optical sensor, to scan the overlap region with the monitoring region of the first optical sensor, to identify the target substance from the measurement data of the at least one further optical sensor and, in the event of an incident, to control at least one further optical sensor, to scan the overlap region with the monitoring region of the first optical sensor, to identify the target substance from the measurement data of the at least one further optical sensor, identifying at least one further solid angle with an infrared signal of the target substance, and determining the coordinates of the overlap region with increased concentration of the target substance from the solid angle information of the first solid angle and of the at least one further solid angle, wherein the measurement signals of the at least one further optical sensor in spatial directions with too small a measurement radius are not included in the evaluation.

Claims

1. A system for monitoring an airspace of an area, with at least two optical sensors with a passive Fourier transform infrared spectrometer and with a server for evaluating the measurement data and for controlling the at least two optical sensors, wherein each optical sensor has an adjustable monitoring range and wherein the monitoring ranges of the at least two optical sensors overlapping at least in sections, and wherein the server is set up, to control the optical sensors in the normal case for an automatic scanning of the monitored areas, wherein the server assigns to the measurement data in each case a solid angle on the basis of the position data of the optical sensor, deriving the spectral intensity distribution of the received IR radiation from the measurement data of the optical sensors for each solid angle and identifying at least one target substance by means of correlation of the intensity distribution with known gas spectra, in case of an incident, when a first optical sensor identifies a target substance in a first solid angle, to control at least one further optical sensor to scan the overlapping area with the monitoring area of the first optical sensor, identifying from the measurement data of the at least one further optical sensor at least one further solid angle with an infrared signal of the target substance, and determining the coordinates of the overlap area with increased concentration of the target substance from the solid angle information of the first solid angle and the at least one further solid angle, wherein the monitoring range of each optical sensor has different measuring radii due to the topography and/or the development of the area as a result of shadowing depending on the solid angle, and the monitoring range of each optical sensor is defined by the solid angle range and the associated measuring radii, that the measuring radii per solid angle are determined and set during the installation of the system for the optical sensors based on the known topography and/or development of the area and wherein the measurement signals of the at least one further optical sensor in spatial directions with too small a measurement radius are not included in the evaluation.

2. (canceled)

3. (canceled)

4. The system according to claim 1, wherein the server is set up to replace the measurement signals of the at least one further optical sensor which have not been included in the evaluation by a weighted mathematical interpolation of spatially adjacent measurement signals.

5. The system according to claim 1, wherein at least three optical sensors are provided and that the server is set up to select, in the event of an incident, at least one further optical sensor for activation whose monitoring range has a maximum overlap with the monitoring range of the first optical sensor.

6. The system according to claim 1, wherein the server is set up to determine the column densities of the target substance from the measurement data of the optical sensors, the column density being the mathematical product of the concentration of the gas and the spatial length of the gas cloud, and that the server is set up to determine the coordinates of the overlapping area of the highest column densities of different optical sensors.

7. The system according to claim 1, wherein at least one stationary detector is provided and the server is set up to use an output signal of the at least one stationary detector as a triggering signal for the deployment of the optical sensors in the spatial area of the stationary detector.

8. The system according to claim 1, wherein at least one sensor is designed as a mobile sensor the mobile sensor being designed as an optical sensor or as a detector.

9. A system for monitoring an airpace of an area, with at least one optical sensor with a passive Fourier transform infrared spectrometer and with a server for evaluating the measurement data and for controlling the at least one optical sensor, wherein the at least one optical sensor has an adjustable monitoring range, wherein at least one mobile airworthy detector is provided and the server is set up, to control the optical sensor to automatically scan the monitoring areas, wherein the server assigns a spatial angle to the measurement data in each case on the basis of the position data of the optical sensor, to derive the spectral intensity distribution of the received IR radiation for each solid angle from the measurement data of the optical sensor and identifying at least one target substance by means of correlation of the intensity distribution with known gas spectra, in which the measuring radii per solid angle are determined and set during the installation of the system for the optical sensors based on the known topography and/or development of the area and in case of an incident, when the optical sensor identifies a target substance in a solid angle, to detect the concentration of the target substance along the solid angle identified by the optical sensor with the at least one mobile detector in a location-dependent manner.

10. The system according to claim 9, wherein the server locates the target substance in the event of an incident by determining that position of the mobile sensor in the monitoring range of the first sensor for which the concentration of the target substance is maximum.

11. A method for monitoring an airspace of an area, in which at least two optical sensors with a passive Fourier transform infrared spectrometer are used to monitor the area at least in sections, in which each optical sensor detects adjustable solid angle ranges within a monitoring area, in which the monitoring area of an optical sensor overlaps at least in sections with the monitoring area of at least one further optical sensor, in which the optical sensors are usually triggered to automatically scan the monitored areas, in which the spectral intensity distribution of the received IR radiation is derived from the measurement data of the optical sensors for each solid angle and a correlation of the intensity distribution with known gas spectra is carried out, in which, in the event of an incident, when an infrared signal of a target substance is identified by a first optical sensor in a first solid angle, at least one further optical sensor is triggered to scan the overlapping area with the monitoring area of the first optical sensor, in which at least one further solid angle with an infrared signal of the target substance is identified from the measurement data of the at least one further optical sensor, and in which the coordinates of the overlap area with increased concentration of the target substance are determined from the solid angle information of the first solid angle and of the at least one further solid angle, that the monitoring range of each optical sensor has different measuring radii due to the topography and/or the area of the terrain as a result of shadowing depending on the solid angle and the monitoring range of each optical sensor is determined and fixed by the solid angle range and the associated measuring radii, in which the measuring radii per solid angle are determined and fixed during the installation of the system for the optical sensors on the basis of the known topography and/or development of the area and wherein measurement signals of the at least one further optical sensor in spatial directions with too small a measurement radius are not included in the evaluation.

12. (canceled)

13. (canceled)

14. The method according to claim 11, in which the measurement signals of the at least one further optical sensor which have not been included in the evaluation are replaced by mathematical interpolation of adjacent measurement signals.

15. The method according to claim 11, in which at least three optical sensors are used, in which an infrared signal of a target substance is identified by the first sensor in the first solid angle, and in which, in the event of an incident, at least the further optical sensor whose monitoring range has a maximum overlap with the monitoring range of the first optical sensor is selected for activation.

16. The method according to claim 11, in which the column density is calculated as the mathematical product of the concentration of the gas and the spatial length of the gas cloud and in which the coordinates of the overlap area of the highest column densities of different optical sensors are determined.

17. (canceled)

18. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0128] In the following, the invention is explained by means of embodiment examples with reference to the drawing. The drawing shows

[0129] FIG. 1 an example of a system according to the invention,

[0130] FIG. 2a,b,c examples of optical sensors,

[0131] FIG. 3 schematic representation of the solid angles of two optical sensors with maximum column densities of a target substance,

[0132] FIG. 4 the illustration according to FIG. 3 additionally with all solid angles with increased column density of a target substance,

[0133] FIG. 5 the illustration according to FIG. 4 with partial shading of a monitoring area,

[0134] FIG. 6 cartographic representation of a harbour with a system with two optical sensors,

[0135] FIG. 7 the illustration according to FIG. 6 with a localised incident,

[0136] FIG. 8a cartographic representation of a chemical plant with a system of passive optical sensors and active measuring sections,

[0137] FIG. 9a cartographic representation of another chemical plant with partial shading of the monitoring areas of three optical sensors,

[0138] FIG. 10 the illustration from FIG. 9 with a changed location of the detected target substance cloud,

[0139] FIG. 11 the illustration from FIG. 8 with a stationary sensor and with a mobile sensor for detecting a target substance cloud, and

[0140] FIG. 12 an embodiment example with an optical sensor and with a mobile non-optical sensor.

DESCRIPTION OF THE INVENTION

[0141] In the following description of the various embodiments according to the invention, components and elements with the same function and the same mode of operation are given the same reference signs, even if the components and elements may differ in dimension or shape in the various embodiments.

[0142] FIG. 1 shows a schematic structure of a system according to the invention for monitoring an airspace for an area.

[0143] The system has two optical sensors 2a and 2b, which are shown in more detail in FIGS. 2a to 2c. Each optical sensor 2 (or 2a and 2b) basically has infrared optics 4 in the form of an IR telescope with parabolic mirror 6 and secondary mirror 8, a video camera 10 or 11, an FTIR spectrometer 12 and a controllable pan-tilt mimic 14 as a positioning unit.

[0144] The two optical sensors 2a and 2b are connected to a supply and interface device 16, which on the one hand provides the supply voltage of, for example, 24 volts for the optical sensors 2a and 2b. On the other hand, data transmission takes place by means of an Ethernet cable to a local area network (LAN). The device 16 can thus transmit control data to the optical sensors 2a or 2b on the one hand and receive the measurement data on the other hand. Alternatively, it can be provided that the interface device 16 and/or the sensors 2a, 2b receive the control data wirelessly and/or transmit the measurement data wirelessly.

[0145] Data is exchanged with a server 20 via fibre optic cables (LWL), in which computer programs for controlling the optical sensors 2a and 2b, for analysing and displaying the data and for storing the measurement data in particular in a database are stored and run.

[0146] Via an interface, the output information is forwarded to a process control system and a video management system located in the vicinity of the monitored area. Thus, an alarm can also be triggered here in the event of an incident (bell symbol) and at the same time the relevant information can be displayed to a user.

[0147] Furthermore, the system can also enable a transfer of data to a cloud application and/or have a direct data connection with an external server 30. The external server 30 can then be used for support functions (telephone, support, service, maintenance) and for supporting a development team with experts.

[0148] FIG. 2a shows the optical sensor 2 described above for monitoring an airspace for an area, with an FTIR spectrometer 12 for detecting target substances, with infrared optics 4 for imaging a partial section of the airspace of the area to be monitored onto the FTIR spectrometer 12, with a video camera 10 and with a positioning unit 14 for aligning the sensor unit formed by the FTIR spectrometer 12, the infrared optics 4 and the camera 10. In this case, the infrared optics 4 and the camera 10 detect essentially the same solid angle, in particular the optical axis O.sub.1 of the infrared optics and the optical axis O.sub.2 of the camera 10 are aligned parallel to each other.

[0149] In the embodiment shown, the infrared optics 4 is designed as a Cassegrain telescope with a parabolic mirror 6 and a secondary mirror 8. Alternatively, but not shown, the infrared optics can also be designed as lens optics.

[0150] The camera 10 is arranged laterally to the infrared optics 4 and therefore has sufficient installation space to be equipped with a telephoto lens to thus produce a high image quality of the monitored partial section of the airspace of the area. However, for an accurate overlay of the measurement data of target clouds, the parallax must be compensated by the distance of the optical axes.

[0151] FIG. 2b shows another example of an optical sensor 2. In contrast to FIG. 2a, a camera 11 is arranged in the optical axis of the infrared optics 4 at the front end of the secondary mirror. Thus the optical axis O.sub.2 of the infrared optics 4 and the optical axis O.sub.3 of the camera 11 coincide and a parallax effect is avoided. Due to the small size of the camera 11, which may be a smartphone camera, for example, the angle of observation is usually large, so that the angle of observation may be larger and the spatial resolution of the camera image smaller than with a camera with a telephoto lens. However, smartphone cameras with a telephoto function are already known, so that the camera 10 can be completely replaced.

[0152] FIG. 2c shows a further example of an optical sensor 2. In contrast to FIGS. 2a and 2b, the camera is designed as a camera system with a camera 10 arranged laterally to the infrared optics 4 and with a camera 11 arranged in the optical axis O.sub.2 of the infrared optics 4. Thus, the optical axis O.sub.1 of the camera 10 runs at a distance from the optical axis O.sub.2 of the infrared optics 4, whereby the optical axis O.sub.3 of the camera 11 coincides with the optical axis O.sub.2 and thus has no or only a small distance therefrom.

[0153] FIG. 3 shows a schematic representation of the monitoring by two optical sensors 2a and 2b. The first optical sensor 2a has a monitoring area which is marked with dashed lines and is approx. 35° wide. The optical sensor 2a usually scans the monitoring area at least partially along a predetermined path. The second optical sensor 2b has a monitoring range of approximately 90°, as also shown with dashed lines. The second optical sensor 2b also automatically scans the monitoring area at least partially along a preset path. Preferably, the scanning is repeated cyclically. The monitoring areas of both optical sensors overlap. During the measurements, the data is transferred to the server 30 and combined with the position data (solid angle).

[0154] The spectral intensity distribution of the received IR radiation is derived from the measurement data of the optical sensors 2a and 2b for each solid angle in order to identify at least one target substance by correlating the intensity distribution with known gas spectra. For this purpose, a corresponding computer program runs on the server 30 or, if applicable, in the optical sensor 2a or 2b.

[0155] In the event of an incident, i.e. when the first optical sensor 2a identifies a target substance, i.e. a gas of the target substance list in a solid angle Θ.sub.1, the further optical sensor 2b is triggered to scan the overlapping area with the monitoring area of the first optical sensor.

[0156] From the measurement data of the optical sensor 2b, a further solid angle Θ.sub.2 is identified with an infrared signal of the target substance, so that the coordinates of the overlapping area (black area) with increased concentration of the target substance can be determined from the solid angle information of the first solid angle Θ.sub.1 and the further solid angle Θ.sub.2.

[0157] FIG. 4 shows an extended representation of FIG. 3, in which the dotted areas of the monitoring areas of the optical sensors 2a and 2b represent the solid angle areas in which at least a low concentration of the target substance has been identified. The solid angle areas Θ.sub.1 and Θ.sub.2 already shown in FIG. 3 show the solid angle areas with the highest concentration of the target substance, which has been determined by calculating the column density. For the calculation of the column density see the general description above. According to FIG. 4, not only the centre of the gas cloud of the target substance (black field), but also the expansion of the cloud can be determined.

[0158] FIG. 5 shows a similar illustration as in FIG. 4. Here, a tower 40 is arranged on the monitored area in the monitoring area of the second optical sensor 2b, so that the area located by the optical sensor 2b behind the tower 40 is shadowed. The shadowed area can thus not be monitored by the optical sensor 2b, the measuring radius of the optical sensor 2b in this area only reaches up to the tower 40 and thus not up to the monitoring area of the optical sensor 2a. For this reason, the “shadow” is not dotted in FIG. 5.

[0159] When searching for the exact localisation of the cloud from the target material, the measurement signals of the optical sensor 2b in spatial directions with too small a measurement radius are not included in the evaluation. Here, the measurement radii are too small for the solid angles covered by the tower 40 and the monitoring areas of the sensors 2a, 2b do not overlap in a shadow behind the tower 40. Nevertheless, the extent of the cloud of the target substance can be almost completely detected. By not taking into account the measurement data in spatial directions with too small a measurement radius, the evaluation is not falsified, because in the monitoring area that ends at the tower 40, the measurement signal will not give any indication of the target substance, although this would be the case without the presence of the tower 40, see FIG. 4.

[0160] If necessary, the server 20 can be set up, i.e. by using computer programs, to replace the measurement signals of the further optical sensor 2b that have not been included in the evaluation by mathematical interpolation of adjacent measurement signals of the optical sensor 2b. Adjacent measurement signals are those whose assigned solid angle ranges are adjacent to the solid angle ranges of the measurement signals that have not been included.

[0161] FIGS. 6 and 7 show a system for monitoring an airspace of a harbour basin area in which the two optical sensors 2a and 2b are positioned at prominent positions within the harbour area.

[0162] FIG. 6 shows the standard case in which the two optical sensors 2a and 2b independently scan the airspace above the area within the monitoring areas marked with dashed lines.

[0163] FIG. 7 shows the incident case as described above. The server 20 is set up by using a computer program to determine the coordinates of the overlap area (black area in FIG. 7) of the solid angle areas Θ.sub.1 and Θ.sub.2 of the highest column densities of the two optical sensors 2a and 2b and to link the coordinates with a map representation and to create a two-dimensional representation of the incident. Preferably, a three-dimensional representation can also be created by linking with images from the cameras 11 of the sensors 2a, 2b.

[0164] FIG. 8 shows another system for monitoring an airspace for an extensive chemical production area. Again, two optical sensors 2a and 2b are arranged at prominent positions. In addition, three active infrared radiation sources 18a, 18b and 18c are arranged in such a way that one of each of the optical sensors 2a or 2b picks up the infrared light. This enables a more precise measurement of the gases contained in the atmosphere along the established measurement paths (thick lines in FIG. 8). Furthermore, the spectral range for evaluation can also be broadened, which allows a larger number of target substances to be measured. Among other things, the active measurements enable a more precise background determination of the gas distribution as well as a larger target substance library. Furthermore, the active infrared radiation sources 18a, 18b, 18c enable separate monitoring of predefined boundary areas, such as plant boundaries.

[0165] FIG. 9 shows a cartographic representation of another chemical plant with partial shading of the monitoring areas of three optical sensors 2a, 2b and 2c.

[0166] There are buildings 50, 52 and 54 on the premises which partially shade the monitoring area of the optical sensor 2a, resulting in shadow areas A.sub.1, A.sub.2 and A.sub.3 respectively. The monitoring range of the optical sensor 2a therefore only extends as far as the building 50, 52 or 54 in each of the assigned spatial angles.

[0167] In the same way, shading areas B.sub.1 and B.sub.2 result for optical sensor 2b and shading areas C.sub.1, C.sub.2 and C.sub.3 for optical sensor 2c.

[0168] FIG. 9 shows the system with the three optical sensors 2a, 2b and 2c with a target substance cloud 56. The target substance cloud 56 is detected first by the sensor 2a in the normal case of the scanning optical sensors 2a, 2b and 2c and an incident case is determined.

[0169] The server not shown in this figure is set up to select at least one further optical sensor 2b for activation in this incident, whose monitoring range has a maximum overlap with the monitoring range of the first optical sensor 2a. The shadows B.sub.1 and B.sub.2 lie outside the solid angle range Θ.sub.1 of the first optical sensor 2a, so that a maximum overlap is given by the monitoring range of the sensor 2b. The second sensor 2b then detects the target substance cloud 56 within the solid angle range Θ.sub.2 and the target substance cloud 56 is localised.

[0170] The third sensor 2c is not selected in this scenario because the shadowing area C.sub.3 overlaps part of the solid angle range Θ.sub.1. A selection of the optical sensor 2c would then also not have led to a positive measurement of the target substance cloud 56, because the target substance cloud 56.sub.3 lies completely in the shadowing area C. The measurement radius of the third sensor 2c is therefore too small here in the solid angle range Θ.sub.3. The potential solid angle Θ.sub.3 is only shown as a dashed line because the shadowing by the building 52 prevents measurement of the target substance cloud 56.

[0171] FIG. 10 shows the illustration from FIG. 9 with a changed location of the detected target substance cloud 56.

[0172] After the optical sensor 2a has detected the target substance cloud, the server searches for another optical sensor to achieve the localisation of the target substance cloud 56. It is found that both optical sensors 2b and 2c each have a shadowing area that overlaps with the solid angle area Θ.sub.1. However, the optical sensor 2b is not selected by the server because the position of the optical sensor 2b is in the direction of the solid angle range Θ.sub.1 of the first optical sensor 2a with detected target substance. Therefore, the third optical sensor 2c, whose monitoring area has solid angles with a larger angle to the measured solid angle area Θ.sub.1 of the first optical sensor 2a, is selected to identify the target substance cloud 56, determine the solid angle area Θ.sub.3 and thus the coordinates of the target substance cloud 56.

[0173] FIG. 11 shows a further example of an embodiment of a system according to the invention, which is based on the embodiment according to FIG. 8.

[0174] In addition to the embodiment of the system described above, it is additionally provided here that stationary detectors 60, which are designed as chemo-electric detectors. The server (not shown here) is set up to use an output signal of the at least one stationary detector 60 as a triggering signal for the use of the optical sensors 2a, 2b in the spatial area of the stationary detector. A plurality of detectors 60 are shown, all of which are positioned in solid angle ranges that can be detected by the optical sensors 2a and 2b. Even though several detectors 60 are shown here, it is sufficient within the scope of the invention if only one detector 60 is present.

[0175] If an incident occurs with a leakage of a target substance and a cloud 62 spreads, then the detector 60 located in the cloud 62 can detect the target substance and send a corresponding signal to the server. Subsequently, the two optical sensors 2a and 2b, if they have not yet detected the incident, can detect the gas cloud 62 and process it as described above.

[0176] As can be seen in FIG. 11, at least one mobile sensor 70 can be mounted on a drone 72. The mobile sensor 70 can be an optical sensor 2 or a detector 60. As shown with a dashed line, the mobile sensor 70 is guided to the cloud 62 in the event of an incident and can make additional measurements on site, which can be evaluated by the system and the server.

[0177] If the mobile sensor 70 has an optical sensor 2, then the measurement signal from the mobile sensor 70 can be evaluated together with the measurement signals from the other stationary optical sensors 2a and 2b, as described previously.

[0178] If the mobile sensor 70 has a detector 60, then the variability of the positions of the mobile sensor 70 allows further data to be collected in addition to the readings from the stationary detector 60.

[0179] FIG. 12 shows a further example of a system according to the invention. This system corresponds essentially to the system in FIG. 4, but only one optical sensor 2 with a passive Fourier transform infrared spectrometer is present. As described above, a server (not shown) is provided for evaluating the measurement data and for controlling the optical sensor 2. The optical sensor 2 has—as described—an adjustable monitoring range.

[0180] A mobile airworthy sensor 70 of the type described above is provided, which is attached to a drone 72 described above. In case of an incident, i.e. when the optical sensor 2 identifies a target substance in a solid angle (shown dotted) whose column density is highest within the angle Θ.sub.1, the mobile sensor 70 is controlled by the server to detect the concentration of the target substance along the solid angle identified by the optical sensor 2 in a location-dependent manner. The corresponding flight path is shown in dashed lines in FIG. 12.

[0181] Thus, with only one optical sensor 2 and one mobile sensor 70, the location of the maximum concentration of the target substance, shown as a black area, can be determined.