EP3321907B1 - Fiber optic based smoke and/or overheat detection and monitoring for aircraft - Google Patents
Fiber optic based smoke and/or overheat detection and monitoring for aircraft Download PDFInfo
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- EP3321907B1 EP3321907B1 EP17201040.7A EP17201040A EP3321907B1 EP 3321907 B1 EP3321907 B1 EP 3321907B1 EP 17201040 A EP17201040 A EP 17201040A EP 3321907 B1 EP3321907 B1 EP 3321907B1
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Classifications
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- G—PHYSICS
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- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/10—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means
- G08B17/103—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device
- G08B17/107—Actuation by presence of smoke or gases, e.g. automatic alarm devices for analysing flowing fluid materials by the use of optical means using a light emitting and receiving device for detecting light-scattering due to smoke
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- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B17/00—Fire alarms; Alarms responsive to explosion
- G08B17/06—Electric actuation of the alarm, e.g. using a thermally-operated switch
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- G—PHYSICS
- G08—SIGNALLING
- G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
- G08B13/00—Burglar, theft or intruder alarms
- G08B13/18—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength
- G08B13/181—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems
- G08B13/187—Actuation by interference with heat, light, or radiation of shorter wavelength; Actuation by intruding sources of heat, light, or radiation of shorter wavelength using active radiation detection systems by interference of a radiation field
Definitions
- Fire detection in aircraft utilizes smoke detection and overheat sensors to quickly and efficiently detect fires.
- Current aircraft regulations require that a system must detect a fire in the cargo compartment and provide visual indication to the crew within one minute. Further, lavatory systems and avionics bay systems conform to specific requirements for those areas. However, fires that are much smaller in size, in critical locations and sometimes in confined locations possess a special risk. Early reliable detection would allow for better control of the fire. Higher sensitivity enables earlier detection, but increases the risk of false alarms. Advances in signal processing and sensor design for point sensors and aspirating systems have decreased nuisance alarms by incorporating temperature and smoke detection.
- JPH0291548 discloses an optical fiber fire sensor capable of detecting multiple fires at the same time.
- the present invention provides a method of monitoring fire conditions as claimed in claim 1.
- the present invention also provides a system for monitoring fire conditions as claimed in claim 5.
- the light source is selectively operated to transmit the light signal.
- a wavelength of the transmitted light is selectably changed.
- the one or more light sensitive devices includes a first light sensitive device configured to receive light from the first fiber optic cable and a second light sensitive device configured to receive light from the second fiber optic cable.
- the light sensitive device is a photodiode.
- the light sensitive device converts the scattered light signal received at the control system into an electrical signal receivable by the control unit.
- the first fiber optic cable defines a plurality of nodes arranged within the aircraft structure.
- the aircraft structure is one or more of a cargo compartment, an avionics bay or other enclosed portion of the aircraft.
- the detection system 20 may be able to detect one or more hazardous conditions, including but not limited to the presence of smoke, fire, temperature, flame, or any of a plurality of pollutants, combustion products, or chemicals. Alternatively, or in addition, the detection system 20 may be configured to perform monitoring operations of people, lighting conditions, or objects. In an embodiment, the system 20 may operate in a manner similar to a motion sensor, such as to detect the presence of a person, occupants, or unauthorized access to the designated area for example.
- the conditions and events described herein are intended as an example only, and other suitable conditions or events are within the scope of the disclosure.
- the detection system 20 uses light to evaluate a volume for the presence of a condition.
- the term "light” means coherent or incoherent radiation at any frequency or a combination of frequencies in the electromagnetic spectrum.
- the photoelectric system uses light scattering to determine the presence of particles in the ambient atmosphere to indicate the existence of a predetermined condition or event.
- the term “scattered light” may include any change to the amplitude/intensity or direction of the incident light, including reflection, refraction, diffraction, absorption, and scattering in any/all directions.
- light is emitted into the designated area; when the light encounters an object (a person, smoke particle, or gas molecule for example), the light can be scattered and/or absorbed due to a difference in the refractive index of the object compared to the surrounding medium (air). Depending on the object, the light can be scattered in all different directions. Observing any changes in the incident light, by detecting light scattered by an object for example, can provide information about the designated area including determining the presence of a predetermined condition or event.
- an object a person, smoke particle, or gas molecule for example
- the detection system 20 includes a single fiber optic cable 28 with at least one fiber optic core.
- the term fiber optic cable 28 includes any form of optical fiber.
- an optical fiber is a length of cable that is composed of one or more optical fiber cores of single-mode, multimode, polarization maintaining, photonic crystal fiber or hollow core.
- a node 34 is located at the termination point of a fiber optic cable 32 and is inherently included in the definition of a fiber optic cable 28. The node 34 is positioned in communication with the ambient atmosphere.
- a light source 36 such as a laser diode for example, and a light sensitive device 38, such as a photodiode for example, are coupled to the fiber optic cable 28.
- a control system 50 of the detection system 20, discussed in further detail below, is utilized to manage the detection system operation and may include control of components, data acquisition, data processing and data analysis.
- the light from the light source is transmitted through the node 34 to the surrounding area, illustrated schematically at 21.
- the light 21 interacts with one or more particles indicative of a condition, illustrated schematically at 22, and is reflected or transmitted back to the node 34, illustrated schematically at 23.
- a comparison of the light provided to the node 34 and/or changes to the light reflected back to the light sensitive device 38 from the node 34 will indicate whether or not changes in the atmosphere are present in the ambient atmosphere adjacent the node 34 that are causing the scattering of the light.
- the scattered light as described herein is intended to additionally include reflected, transmitted, and absorbed light.
- the detection system 20 can include a plurality of nodes 34.
- a plurality of fiber optic cables 28 and corresponding nodes 34 are each associated with a distinct light sensitive device 38.
- the signal output from each node 34 can be monitored.
- a predetermined event or condition it will be possible to localize the position of the event because the position of each node 34 within the system 20 is known.
- a plurality of fiber optic cables 28 are coupled to a single light sensitive device.
- the control system 50 is able to localize the scattered light, i.e. identify the scattered light received from each of the plurality of nodes 34.
- the control system 50 uses the position of each node 34, specifically the length of the fiber optic cables 28 associated with each node 34 and the corresponding time of flight (i.e. the time elapsed between when the light was emitted by the light source 36 and when the light was received by the light sensitive device 38), to associate different parts of the light signal with each of the respective nodes 34 that are connected to that light sensitive device 38.
- the time of flight may include the time elapsed between when the light is emitted from the node and when the scattered light is received back at the node. In such embodiments, the time of flight provides information regarding the distance of the object relative to the node.
- two substantially identical and parallel light transmission fiber cores 40, 42 are included in the fiber optic cable 28 and terminate at the node 34.
- the light source 36 may be coupled to the first fiber core 40 and the light sensitive device 38 may be coupled to the second fiber core 42, for example near a first end of the fiber optic cable 28.
- the light source 36 is selectively operable to emit light, which travels down the first fiber core 40 of the fiber optic cable 28 to the node 34. At the node 34, the emitted light is expelled into the adjacent atmosphere. The light is scattered and transmitted back into the node 34 and down the fiber cable 28 to the light sensitive device 38 via the second fiber core 42.
- the detection system 20 includes a fiber harness 30 having a plurality of fiber optic cables 28 bundled together.
- a fiber harness 30 can also be only a single fiber optic cable 28.
- a plurality of fiber cores 40, 42 are bundled together at a location to form a fiber harness backbone 31 with the ends of the fiber optic cables 28 being separated (not included in the bundled backbone) to define a plurality of fiber optic branches 32 of the fiber harness 30.
- the plurality of fiber cores 40, 42 branch off to form a plurality of individual fiber branches 32, each of which terminates at a node 34.
- the fiber harness 30 additionally includes an emitter leg 33 and a receiver leg 35 associated with the fiber branches 32.
- the emitter leg 33 may contain the first fiber cores 40 from each of the plurality of fiber branches 32 and the receiver leg 35 may contain all of the second fiber cores 42 from each of the fiber branches 32.
- the length of the fiber optic cores 40, 42 extending between the emitter leg 33 or the receiver leg 35 and the node 34 may vary in length such that the branches 32 and corresponding nodes 34 are arranged at various positions along the length of the fiber harness backbone 31. In an embodiment, the positions of the nodes 34 may be set during manufacture, or at the time of installation of the system 20.
- the fiber harness 30 may include a fiber optic cable (not shown) having a plurality of branches 32 integrally formed therewith and extending therefrom.
- the branches 32 may include only a single fiber optic core.
- the configuration, specifically the spacing of the nodes 34 within a fiber harness 30 may be substantially equidistant, or may vary over the length of the harness 30. In an embodiment, the positioning of each node 34 may correlate to a specific location within the designated area.
- the detection system 20 may additionally include a plurality of fiber harnesses 30.
- a distinct light sensitive device 38 is associated with each of the plurality of fiber harnesses 30.
- a single light source 36 is operably coupled to the plurality of light transmission fiber cores 40 within the plurality of fiber harnesses 30 of the system 20.
- the detection system 20 may be configured to monitor a predetermined area such as a building.
- the detection system 20 may be especially utilized for predetermined areas having a crowded environment, such as a server room, as shown in FIG. 6 for example.
- Each fiber harness 30 may be aligned with one or more rows of equipment 46, and each node 34 therein may be located directly adjacent to one of the towers 48 within the rows 46.
- nodes may be arranged so as to monitor specific enclosures, electronic devices, or machinery. Positioning of the nodes 34 in such a manner allows for earlier detection of a condition as well as localization, which may limit the exposure of the other equipment in the room to the same condition.
- the detection system 20 may be integrated into an aircraft, such as for monitoring a cargo bay, avionics rack, lavatory, or another confined region of the aircraft that may be susceptible to fires or other events.
- the processor 54 may be coupled to the at least one light source 36 and the at least one light sensitive device 38 via connectors.
- the light sensitive device 38 is configured to convert the scattered light received from a node 34 into a corresponding signal receivable by the processor 54.
- the signal generated by the light sensing device 38 is an electronic signal.
- the signal output from the light sensing device 38 is then provided to the control unit 52 for processing using an algorithm to determine whether a predefined condition is present.
- the signal received by or outputted from the light sensitive device(s) 38 may be amplified and/or filtered, such as by a comparator (not shown), to reduce or eliminate irrelevant information within the signal prior to being communicated to the control unit 52 located remotely from the node 34.
- the amplification and filtering of the signal may occur directly within the light sensing device 38, or alternatively, may occur via one or more components disposed between the light sensing device 38 and the control unit 52.
- the control unit 52 may control the data acquisition of the light sensitive device 38, such as by adjusting the gain of the amplifier, the bandwidth of filters, sampling rates, the amount of timing and data buffering for example.
- Data representative of the output from each APD sensor 64 in the APD array 66 is periodically taken by a switch 68, or alternatively, is collected simultaneously.
- the data acquisition 67 collects the electronic signals from the APD and associates the collected signals with metadata.
- the metadata as an example can be time, frequency, location or node.
- the electronic signals are from the APD are synchronized to the laser modulation such that the electrical signals are collected for a period of time that starts when the laser is pulsed to several microseconds after the laser pulse.
- the data will be collected and processed by the processor 54 to determine whether any of the nodes 34 indicates the existence of a predefined condition or event.
- the switch 68 is therefore configured to collect information from the various APD sensors 64 of the sensor array 66 sequentially. While the data collected from a first APD sensor 64 is being processed to determine if an event or condition has occurred, the data from a second APD 66 of the sensor array 66 is collected and provided to the processor 54 for analysis. When a predefined condition or event has been detected from the data collected from one of the APD sensors 64, the switch 68 may be configured to provide additional information from the same APD sensor 64 to the processor 54 to track the condition or event.
- the scattered light may include one or more of scattered light within the atmosphere adjacent the node and scattered light that reflects from an interior of the fiber optic branch 32.
- the scattered light is transmitted to the at least one light sensing device 38 in block 108.
- the light sensing device 38 generates a signal in response to the scattered light received by each node 34, and provides that signal to the control unit 52 for further processing.
- each of the signals representing the scattered light received by the corresponding nodes 34 are evaluated to determine whether the light at the node 34 is indicative of a predefined condition, such as smoke for example.
- a schematic diagram illustrating an example of a flow path for processing the signals generated by each of the nodes 34 is illustrated.
- the signal indicative of scattered light 69 is parsed, shown at block 70, into a plurality of signals based on their respective originating node 34.
- background signals illustrated schematically at 72, are subtracted from the data before the pulse features are evaluated for each of the individual signals.
- one or more characteristics or features (pulse features) of the signal may be determined.
- characteristics or features include, but are not limited to, a peak height, an area under a curve defined by the signal, statistical characteristics such as mean, variance, and/or higher-order moments, correlations in time, frequency, space, and/or combinations thereof, and empirical features as determined by deep learning, dictionary learning, and/or adaptive learning and the like.
- the time of flight record is parsed and features are extracted.
- the time of flight record can cover a period of time.
- a time of flight record can record light intensity over 0.001 -1,000,000 nanoseconds, 0.1-100,000 nanoseconds, or 0.1-10,000 microseconds.
- the features extracted from the signal can include, but are not limited to height, full width at half maximum, signal pick up time, signal drop off time, group velocity, integration, rate of change, mean, and variance for example.
- the features may then be further processed by using, for example, smoothing, Fourier transforms or cross correlation.
- the processed data is then sent to the detection algorithm at block 78 to determine whether or not the signal indicates the presence and/or magnitude of a condition or event at a corresponding node 34.
- This evaluation may be a simple binary comparison that does not identify the magnitude of deviation between the characteristic and a threshold.
- the evaluation may also be a comparison of a numerical function of the characteristic or characteristics to a threshold.
- the threshold may be determined a priori or may be determined from the signal.
- the determination of the threshold from the signal may be called background learning. Background learning may be accomplished by adaptive filtering, model-based parameter estimation, statistical modeling, and the like.
- the remainder of the detection algorithm is not applied in order to reduce the total amount processing done during the detection algorithm.
- an alarm or other fire suppression system may, but need not be activated. It should be understood that the process for evaluating the data illustrated and described herein is intended as an example only and that other processes including some or all of the steps indicated in the FIG. are also contemplated herein.
- the evaluation may also advantageously employ classifiers including those that may be learned from the signal via deep learning techniques including, but not limited to deep neural networks, convolutional neural networks, recursive neural networks, dictionary learning, bag of visual/depth word techniques, Support Vector Machine (SVM), Decision Trees, Decision Forests, Fuzzy Logic, and the like.
- the classifiers may also be constructed using Markov Model techniques, Hidden Markov Models (HMM), Markov Decision Processes (MDP), Partially Observable MDPs, Markov Decision Logic, Probabilistic Programming, and the like.
- the magnitude and presence of a condition may be calculated utilizing one or more evaluation approaches: a threshold, velocity, rate of change or a classifier.
- the detection algorithm may include utilizing the output from the calculation causality, dependency or both. This is used to indicate the presence of the condition at one or more nodes 34 and initiate a response.
- the algorithm 58 is configured to distinguish between different events or conditions based on the rate of change in the light scattered by the atmosphere near the node 34 and received by one or more of the nodes 34 over time.
- FIGS. 11A and 11B graphs of the signals recorded from a node 34 over time with respect to different events are illustrated.
- FIG. 11A indicates the change in the light signal received by a node 34 as a person walks through the area being monitored by the node 34. As shown in the graph, the movement of a person appears as steps having varying magnitudes.
- FIG. 11A indicates the change in the light signal received by a node 34 as a person walks through the area being monitored by the node 34. As shown in the graph, the movement of a person appears as steps having varying magnitudes.
- FIG. 11A indicates the change in the light signal received by a node 34 as a person walks through the area being monitored by the node 34. As shown in the graph, the movement of a person appears as steps having varying magnitudes.
- each predefined event detectable by the detection system 20 may have one or more unique parameters associated therewith.
- the optical enhancement device 80 is placed so that light scattered and reflected back to the light sensitive device 38 is passed through the optical enhancement device 80 to filter or differentiate events or other conditions to be sensed from other signals due to, for example, ambient light, solid objects, bugs, dust, or water vapor.
- optical enhancement device 80 is located at the light sensitive device 38 or embedded in the light sensitive device 38, in other embodiments the optical enhancement device 80 is located at other locations, such as at the node 34 as shown in FIG. 13 . This allows for node-specific placement of optical enhancement devices 80 such that different optical enhancement devices 80 may be placed at different nodes 34. Further, in some embodiments, combinations of optical enhancement devices 80, such as combinations of bandpass filters and polarizers, may be utilized to filter or disseminate certain conditions of the scattered/reflected light. Further, in systems 20 where the nodes 34 include two or more cores 40, 42, optical enhancements 80 may be located at an individual core 40, 42 or at two or more of the cores 40, 42.
- the system 20 includes focusing or expanding optical elements to increase range, sensitivity or field of view of the detection system 20 in detecting smoke/gas or other conditions or events.
- a focusing optical element can be placed at the node or between the control system and fiber harness to increase range and sensitivity by converging or collimating light.
- an expanding optical element can be placed in similar locations to increase the field of view of the node by diverging the light.
- optical elements may include mirrors, focusing lenses, diverging lenses, and diffusers, along with the integration of antireflective coatings on the optical elements or components thereof.
- the optical elements may include a parabolic mirror 86 located at the node 34.
- the parabolic mirror 86 is located offangle relative to a node axis 88. As with the lens 84, the parabolic mirror 86 reduces divergence of the outgoing beam transmitted from the light source 36, while also increasing an amount of scattered light accepted by the node 34 for transmission to the light sensitive device 38.
- the parabolic mirror 86 is configured to rotate about a rotational axis during operation of the system 20 to further increase a coverage area of the node 34.
- one or more lasers may be utilized to emit several wavelengths.
- the control system can provide selectively controlled emission of the light. Utilization of the system 20 for pollutant detection can lead to improved air quality in the predetermined space 82 as well as improved safety.
- the fiber optic branches 32 are each operably connected to the fiber harness backbone 31, which may only include a single fiber optic core, via a coupling 132.
- the coupling 132 is one of a splice connection, a fused connection or a solid state switching device. Utilizing couplings 132 allows nodes 34 to be added to the fiber harness 30 after installation of the fiber harness 30, or removal or relocation of the nodes 34 once the fiber harness 30 is installed. The couplings 132 therefore increase flexibility of the fiber harness 30 and the system 20.
- a first fiber optic core 40 is operably coupled to a first node 34, while a second node 34 is operably coupled to a second fiber optic core 42.
- the first fiber optic core 40 is utilized for transmission of light from the light source 36, while the second fiber optic core 42 receives scattered light and conveys the scatter light to the light sensitive device 38.
- a first coupling 132a coupling the first fiber optic core 40 to the first node 34 is the same as a second coupling 132b coupling the second fiber optic core 42 to the second node 34, while in other embodiment the first coupling 132a is different from the second coupling 132b.
- the control system 50 is configured for multiple inputs and/or multiple outputs for communication of information through the fiber optic cables 28 and the nodes 34.
- the multiple inputs and outputs may include an internet connection 140, a building network or management system 142, and/or a fire panel 134 of the building or enclosed space.
- the fire panel 134 is configured for communications with, for example, a fire department, and/or is configured to transmit alarms through the building or space in the event of detection of smoke, fire or other substance by the system 20.
- the fiber optic cables 28 are further utilized for the communication of alarms, alerts and other information, such as system diagnostic information through the building.
- the control system 50 is able to both measure the condition in the predetermined area 82 and provide communication. For example, once the control system 50 determines that a condition is present based on detection signals received from one or more nodes 34, the control system 50 transmits one or more alarm signals from the fire panel 134 along fiber optic cables 28 to one or more alarm units 138 in the building or space which initiate an alarm or alert based on the received alarm signals. The control system 50 is able to do this in a fiber optic harness 30 by combining frequency and amplitude modulation of the light.
- the alert or alarm is an audible sound or sounds, while in other embodiments the alert or alarm is a light, or a combination of light and sound.
- control system 50 may be configured to send and/or receive communication through the fiber optic cables 28 and the nodes 34 to communicate with one or more building infrastructure or local devices in the space via modulated light transmitted along the cables 32.
- this communication is via Li-Fi protocol.
- control unit 52 may command powering down of electronic components 124 in the node 34 region to prevent further damage to the particular electronic components 124.
- Localized detection and suppression such as described herein via detection system 20 and suppression system 126, provides protection of electronic components 124 from fire and smoke, while localizing suppression to protect such components not subjected to fire and smoke from exposure to suppressant, reducing damage to those components and further reducing cost and expense of suppressant cleanup after an event.
- the aircraft 200 includes a fuselage 202 with wings 204 extending therefrom. Further, the aircraft 200 includes one or more compartments, i.e. the predetermined area, at which it is desired to provide fire, smoke and/or heat detection capabilities. These compartments may include a cargo bay 206, a lavatory 208, an avionics bay 210 or the like. One skilled in the art will readily recognize that the listed compartments are exemplary and that the present disclosure may be readily applied to other compartments of the aircraft 200.
- Embodiments of detection system 20 are installed in the aircraft 200 to detect fire, smoke and/or heat at the compartments 206, 208, 210.
- a fiber harness 30 is connected to a control system 50 at a port 212 and can have one or more fiber optic cables 28 extending to the compartments 206, 208, 210.
- different fiber optic cables 28 or fiber optic cores in the fiber harness 30 will be used for smoke/fire detection, while others are used for temperature measurements.
- the control system 50 is utilized to evaluate scattered light from the fiber harness 30 for both smoke detection and temperature/overheat detection.
- a comparison of the light transmitted by the light source 36 and scattered light received at the light sensitive device 38 will indicate whether or not changes in the atmosphere adjacent to the node 34 are present. For example, the presence of smoke or other particles in the atmosphere will cause the light emitted through the node to scatter outside of the fiber.
- the detection system 20 is described as using light scattering to determine a condition or event, embodiments where light obscuration, absorption, and fluorescence is used in addition to light scattering are also within the scope of the disclosure.
- a first fiber optic cable 28 is utilized to monitor a compartment or area for smoke and/or fire conditions, while a second fiber optic cable 28 is utilized to monitor a compartment or area for temperature conditions.
- the first fiber optic cable 28 extends into or through one or more compartments of interest for the detection system 20 to monitor or detect smoke in the compartments
- the second fiber optic cable 28 extends into or through one or more compartments of interest for the detection system 20 to monitor or detect overheat conditions in the compartments.
- the second fiber optic cable can also be extended through one or more compartments in a loop.
Description
- The present disclosure relates to aircraft operation, and more specifically to fire detection in an aircraft utilizing smoke and/or overheat detection.
- Fire detection in aircraft utilizes smoke detection and overheat sensors to quickly and efficiently detect fires. Current aircraft regulations require that a system must detect a fire in the cargo compartment and provide visual indication to the crew within one minute. Further, lavatory systems and avionics bay systems conform to specific requirements for those areas. However, fires that are much smaller in size, in critical locations and sometimes in confined locations possess a special risk. Early reliable detection would allow for better control of the fire. Higher sensitivity enables earlier detection, but increases the risk of false alarms. Advances in signal processing and sensor design for point sensors and aspirating systems have decreased nuisance alarms by incorporating temperature and smoke detection.
- However, overheat and smoke sensors are bulky, limiting their use to larger parts off the airplane, and can be prone to false alarms and are difficult to maintain. Further, such sensors typically require a weight and power budget, and can have difficulty detecting smoke in areas with a high airflow rate. Overheat detectors can have thermistor, eutectic salt, and pneumatic elements. The predominant approach utilizes eutectic salts, which is very sensitive and failsafe. However, the technology is prone to vibration, and is heavy and difficult to maintain during routine aircraft maintenance. New approaches that can reduce the footprint, are vibrationally insensitive and easily maintainable are advantageous. In addition, integrated fire protection technologies that reduce weight, power and foot print are advantageous to the air framer.
-
JPH0291548 - The present invention provides a method of monitoring fire conditions as claimed in
claim 1. The present invention also provides a system for monitoring fire conditions as claimed in claim 5. - In an embodiment the light source is selectively operated to transmit the light signal.
- Additionally or alternatively, in this or other embodiments a wavelength of the transmitted light is selectably changed.
- Additionally or alternatively, in this or other embodiments the scattered light signal is converted into corresponding electrical signals for evaluation by a control unit.
- In an embodiment measuring the temperature further includes determining an overheat condition.
- Additionally or alternatively, in this or other embodiments the one or more light sensitive devices includes a first light sensitive device configured to receive light from the first fiber optic cable and a second light sensitive device configured to receive light from the second fiber optic cable.
- Additionally or alternatively, in this or other embodiments the control unit is operably coupled to the light source to selectively control emission of light from the light source.
- Additionally or alternatively, in this or other embodiments the light sensitive device is a photodiode.
- Additionally or alternatively, in this or other embodiments the light sensitive device converts the scattered light signal received at the control system into an electrical signal receivable by the control unit.
- Additionally or alternatively, in this or other embodiments the first fiber optic cable defines a plurality of nodes arranged within the aircraft structure.
- Additionally or alternatively, in this or other embodiments the aircraft structure is one or more of a cargo compartment, an avionics bay or other enclosed portion of the aircraft.
- The subject matter, which is regarded as the present disclosure, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
-
FIG. 1 is schematic diagram of a detection system not forming part of the present invention; -
FIG. 1A is a schematic diagram of light transmission at a node of a detection system not forming part of the present invention; -
FIG. 2A is a schematic diagram of a detection system not forming part of the present invention; -
FIG. 2B is a schematic diagram of a detection system according to an embodiment; -
FIG. 3 is a cross-sectional view of a fiber optic node of the fiber harness ofFIG. 1 according to an embodiment; -
FIG. 4A is a side view of a fiber harness of a detection system according to an embodiment; -
FIG. 4B is a schematic diagram of a fiber harness of a detection system according to an embodiment; -
FIG. 5 is a schematic diagram of a detection system including a plurality of fiber harnesses according to an embodiment; -
FIG. 6 is a perspective view of an area within a building to be monitored by a detection system according to an embodiment; -
FIG. 7 is a schematic diagram of a control system of the detection system according to an embodiment; -
FIG. 8 is another schematic diagram of a detection system including an avalanche photo diode sensor according to an embodiment; -
FIG. 9 is a method of operating a detection system according to an embodiment; -
FIG. 10 is a schematic diagram of process flow for evaluating the signals generated by the light sensitive device according to an embodiment; -
FIGS. 11A and 11B are diagrams illustrating the signals recorded by the detection system over time for various predefined conditions or events according to an embodiment. -
FIG. 12 is another schematic diagram of a detection system; -
FIG. 13 is yet another schematic diagram of a detection system; -
FIG. 14 is a schematic diagram of a detection system using lenses; -
FIG. 15 is a another schematic diagram of a detection system using mirrors; -
FIG. 16A is a schematic diagram of a detection system having a splice connection; -
FIG. 16B is another schematic diagram of a splice connection for a detection system; -
FIG. 17 is a schematic diagram of a detection system including an optical amplifier; -
FIG. 18 is a schematic diagram of a detection system further configured for communication; -
FIG. 19 is a schematic illustration of a combined detection system and suppression system; and -
FIG. 20 is a schematic view of an aircraft. - The detailed description explains embodiments of the present disclosure, together with advantages and features, by way of example with reference to the drawings.
- The embodiments disclosed and discussed with reference to
figure 20 are embodiments of the present invention. The other disclosed embodiments do no necessarily fall under the scope of the claims but may be useful to understand further aspects of the invention as claimed. - Referring now to the FIGS., a
system 20 for detecting one or more conditions or events within a designated area is illustrated. Thedetection system 20 may be able to detect one or more hazardous conditions, including but not limited to the presence of smoke, fire, temperature, flame, or any of a plurality of pollutants, combustion products, or chemicals. Alternatively, or in addition, thedetection system 20 may be configured to perform monitoring operations of people, lighting conditions, or objects. In an embodiment, thesystem 20 may operate in a manner similar to a motion sensor, such as to detect the presence of a person, occupants, or unauthorized access to the designated area for example. The conditions and events described herein are intended as an example only, and other suitable conditions or events are within the scope of the disclosure. - The
detection system 20 uses light to evaluate a volume for the presence of a condition. In this specification, the term "light" means coherent or incoherent radiation at any frequency or a combination of frequencies in the electromagnetic spectrum. In an example, the photoelectric system uses light scattering to determine the presence of particles in the ambient atmosphere to indicate the existence of a predetermined condition or event. In this specification, the term "scattered light" may include any change to the amplitude/intensity or direction of the incident light, including reflection, refraction, diffraction, absorption, and scattering in any/all directions. In this example, light is emitted into the designated area; when the light encounters an object (a person, smoke particle, or gas molecule for example), the light can be scattered and/or absorbed due to a difference in the refractive index of the object compared to the surrounding medium (air). Depending on the object, the light can be scattered in all different directions. Observing any changes in the incident light, by detecting light scattered by an object for example, can provide information about the designated area including determining the presence of a predetermined condition or event. - In an arrangement not forming part of the present invention, as shown in
FIG. 1 , thedetection system 20 includes a singlefiber optic cable 28 with at least one fiber optic core. The termfiber optic cable 28 includes any form of optical fiber. As examples, an optical fiber is a length of cable that is composed of one or more optical fiber cores of single-mode, multimode, polarization maintaining, photonic crystal fiber or hollow core. Anode 34 is located at the termination point of afiber optic cable 32 and is inherently included in the definition of afiber optic cable 28. Thenode 34 is positioned in communication with the ambient atmosphere. Alight source 36, such as a laser diode for example, and a lightsensitive device 38, such as a photodiode for example, are coupled to thefiber optic cable 28. Acontrol system 50 of thedetection system 20, discussed in further detail below, is utilized to manage the detection system operation and may include control of components, data acquisition, data processing and data analysis. - As shown in
FIG. 1A , the light from the light source is transmitted through thenode 34 to the surrounding area, illustrated schematically at 21. The light 21 interacts with one or more particles indicative of a condition, illustrated schematically at 22, and is reflected or transmitted back to thenode 34, illustrated schematically at 23. A comparison of the light provided to thenode 34 and/or changes to the light reflected back to the lightsensitive device 38 from thenode 34 will indicate whether or not changes in the atmosphere are present in the ambient atmosphere adjacent thenode 34 that are causing the scattering of the light. The scattered light as described herein is intended to additionally include reflected, transmitted, and absorbed light. Although thedetection system 20 is described as using light scattering to determine a condition or event, embodiments where light obscuration, absorption, and fluorescence is used in addition to light scattering are also within the scope of the disclosure. - In another arrangement, the
detection system 20 can include a plurality ofnodes 34. For example, in an arrangement not forming part of the claimed invention as illustrated inFIG. 2A , a plurality offiber optic cables 28 andcorresponding nodes 34 are each associated with a distinct lightsensitive device 38. In arrangements not forming part of the present invention where an individual lightsensitive device 38 is associated with eachnode 34, as shown inFIG. 2A , the signal output from eachnode 34 can be monitored. Upon detection of a predetermined event or condition, it will be possible to localize the position of the event because the position of eachnode 34 within thesystem 20 is known. In an embodiment, as shown inFIG 2B , a plurality offiber optic cables 28, are coupled to a single light sensitive device. - Where a single light
sensitive device 38 is configured to receive scattered light from a plurality ofnodes 34, thecontrol system 50 is able to localize the scattered light, i.e. identify the scattered light received from each of the plurality ofnodes 34. In an embodiment, thecontrol system 50 uses the position of eachnode 34, specifically the length of thefiber optic cables 28 associated with eachnode 34 and the corresponding time of flight (i.e. the time elapsed between when the light was emitted by thelight source 36 and when the light was received by the light sensitive device 38), to associate different parts of the light signal with each of therespective nodes 34 that are connected to that lightsensitive device 38. Alternatively, or in addition, the time of flight may include the time elapsed between when the light is emitted from the node and when the scattered light is received back at the node. In such embodiments, the time of flight provides information regarding the distance of the object relative to the node. - In an embodiment, illustrated in the cross-section of the fiber optic cable shown in
FIG. 3 , two substantially identical and parallel lighttransmission fiber cores fiber optic cable 28 and terminate at thenode 34. However, it should be understood that embodiments where thefiber optic cable 28 includes only a single fiber core, or more than two cores are also contemplated herein. Thelight source 36 may be coupled to thefirst fiber core 40 and the lightsensitive device 38 may be coupled to thesecond fiber core 42, for example near a first end of thefiber optic cable 28. Thelight source 36 is selectively operable to emit light, which travels down thefirst fiber core 40 of thefiber optic cable 28 to thenode 34. At thenode 34, the emitted light is expelled into the adjacent atmosphere. The light is scattered and transmitted back into thenode 34 and down thefiber cable 28 to the lightsensitive device 38 via thesecond fiber core 42. - With reference now to
FIG. 4A , in more complex embodiments, thedetection system 20 includes afiber harness 30 having a plurality offiber optic cables 28 bundled together. It should be noted that afiber harness 30 can also be only a singlefiber optic cable 28. In an embodiment, a plurality offiber cores fiber harness backbone 31 with the ends of thefiber optic cables 28 being separated (not included in the bundled backbone) to define a plurality offiber optic branches 32 of thefiber harness 30. As shown, the plurality offiber cores individual fiber branches 32, each of which terminates at anode 34. In the non-limiting embodiments ofFIGS. 4A and 4B , thefiber harness 30 additionally includes anemitter leg 33 and areceiver leg 35 associated with thefiber branches 32. Theemitter leg 33 may contain thefirst fiber cores 40 from each of the plurality offiber branches 32 and thereceiver leg 35 may contain all of thesecond fiber cores 42 from each of thefiber branches 32. The length of thefiber optic cores emitter leg 33 or thereceiver leg 35 and thenode 34 may vary in length such that thebranches 32 andcorresponding nodes 34 are arranged at various positions along the length of thefiber harness backbone 31. In an embodiment, the positions of thenodes 34 may be set during manufacture, or at the time of installation of thesystem 20. - Alternatively, the
fiber harness 30 may include a fiber optic cable (not shown) having a plurality ofbranches 32 integrally formed therewith and extending therefrom. Thebranches 32 may include only a single fiber optic core. The configuration, specifically the spacing of thenodes 34 within afiber harness 30 may be substantially equidistant, or may vary over the length of theharness 30. In an embodiment, the positioning of eachnode 34 may correlate to a specific location within the designated area. - With reference now to
FIG. 5 , thedetection system 20 may additionally include a plurality of fiber harnesses 30. In the illustrated, non-limiting embodiment, a distinct lightsensitive device 38 is associated with each of the plurality of fiber harnesses 30. However, embodiments where a single lightsensitive device 38 is coupled to the plurality of fiber harnesses 30 are also contemplated here. A singlelight source 36 is operably coupled to the plurality of lighttransmission fiber cores 40 within the plurality of fiber harnesses 30 of thesystem 20. - The
detection system 20 may be configured to monitor a predetermined area such as a building. Thedetection system 20 may be especially utilized for predetermined areas having a crowded environment, such as a server room, as shown inFIG. 6 for example. Eachfiber harness 30 may be aligned with one or more rows ofequipment 46, and eachnode 34 therein may be located directly adjacent to one of thetowers 48 within therows 46. In addition, nodes may be arranged so as to monitor specific enclosures, electronic devices, or machinery. Positioning of thenodes 34 in such a manner allows for earlier detection of a condition as well as localization, which may limit the exposure of the other equipment in the room to the same condition. In another application, thedetection system 20 may be integrated into an aircraft, such as for monitoring a cargo bay, avionics rack, lavatory, or another confined region of the aircraft that may be susceptible to fires or other events. - The
control system 50 of thedetection system 20 is utilized to manage the detection system operation and may include control of components, data acquisition, data processing and data analysis. Thecontrol system 50, illustrated inFIG. 7 , includes at least one lightsensitive device 38, at least one light source, 36, and acontrol unit 52, such as a computer having one ormore processors 54 andmemory 56 for implementing analgorithm 58 as executable instructions that are executed by theprocessor 54. The instructions may be stored or organized in any manner at any level of abstraction. Theprocessor 54 may be any type of processor, including a central processing unit ("CPU"), a general purpose processor, a digital signal processor, a microcontroller, an application specific integrated circuit ("ASIC"), a field programmable gate array ("FPGA"), or the like. Also, in some embodiments,memory 56 may include random access memory ("RAM"), read only memory ("ROM"), or other electronic, optical, magnetic, or any other computer readable medium for storing and supporting processing in thememory 56 . In addition to being operably coupled to the at least onelight source 36 and the at least one lightsensitive device 38, thecontrol unit 52 may be associated with one or more input/output devices 60. In an embodiment, the input/output devices 60 may include an alarm or other signal, or a fire suppression system which are activated upon detection of a predefined event or condition. It should be understood herein that the term alarm, as used herein, may indicate any of the possible outcomes of a detection. - The
processor 54 may be coupled to the at least onelight source 36 and the at least one lightsensitive device 38 via connectors. The lightsensitive device 38 is configured to convert the scattered light received from anode 34 into a corresponding signal receivable by theprocessor 54. In an embodiment, the signal generated by thelight sensing device 38 is an electronic signal. The signal output from thelight sensing device 38 is then provided to thecontrol unit 52 for processing using an algorithm to determine whether a predefined condition is present. - The signal received by or outputted from the light sensitive device(s) 38 may be amplified and/or filtered, such as by a comparator (not shown), to reduce or eliminate irrelevant information within the signal prior to being communicated to the
control unit 52 located remotely from thenode 34. In such embodiments, the amplification and filtering of the signal may occur directly within thelight sensing device 38, or alternatively, may occur via one or more components disposed between thelight sensing device 38 and thecontrol unit 52. Thecontrol unit 52 may control the data acquisition of the lightsensitive device 38, such as by adjusting the gain of the amplifier, the bandwidth of filters, sampling rates, the amount of timing and data buffering for example. - With reference now to
FIG. 8 , in an embodiment of thesystem 20, the lightsensitive device 38 may include one or more Avalanche Photodiode (APD)sensors 64. For example, an array 66 ofAPD sensors 64 may be associated with the one or more fiber harnesses 30. In an embodiment, the number ofAPD sensors 64 within the sensor array 66 is equal to or greater than the total number of fiber harnesses 30 operably coupled thereto. However, embodiments where the total number ofAPD sensors 64 within the sensor array 66 is less than the total number of fiber harnesses 30 are also contemplated herein. - Data representative of the output from each
APD sensor 64 in the APD array 66 is periodically taken by aswitch 68, or alternatively, is collected simultaneously. The data acquisition 67 collects the electronic signals from the APD and associates the collected signals with metadata. The metadata as an example can be time, frequency, location or node. In an example, the electronic signals are from the APD are synchronized to the laser modulation such that the electrical signals are collected for a period of time that starts when the laser is pulsed to several microseconds after the laser pulse. The data will be collected and processed by theprocessor 54 to determine whether any of thenodes 34 indicates the existence of a predefined condition or event. In an embodiment, only a portion of the data outputted by the sensor array 66, for example the data from afirst APD sensor 64 associated with afirst fiber harness 30, is collected. Theswitch 68 is therefore configured to collect information from thevarious APD sensors 64 of the sensor array 66 sequentially. While the data collected from afirst APD sensor 64 is being processed to determine if an event or condition has occurred, the data from a second APD 66 of the sensor array 66 is collected and provided to theprocessor 54 for analysis. When a predefined condition or event has been detected from the data collected from one of theAPD sensors 64, theswitch 68 may be configured to provide additional information from thesame APD sensor 64 to theprocessor 54 to track the condition or event. - A method of
operation 100 of thedetection system 20 is illustrated inFIG. 9 . Thecontrol unit 52 operably coupled to thelight source 36 is configured to selectively energize thelight source 36, as shown inblock 102, and to emit light to afiber harness 30 coupled thereto as shown inblock 104. Based on the desired operation of thedetection system 20, thecontrol unit 52 may vary the intensity, duration, repetition, frequency, or other properties, of the light emitted. As the light travels down thefirst fiber core 40 of the at least onefiber optic branch 32, all or a portion of the light is emitted at one ormore nodes 34 of thefiber harness 30. Inblock 106, light is scattered in the predetermined area and transmitted back through thefiber optic branches 32 via thesecond fiber cores 42. The scattered light may include one or more of scattered light within the atmosphere adjacent the node and scattered light that reflects from an interior of thefiber optic branch 32. The scattered light is transmitted to the at least onelight sensing device 38 inblock 108. As shown inblock 110, thelight sensing device 38 generates a signal in response to the scattered light received by eachnode 34, and provides that signal to thecontrol unit 52 for further processing. - Using the
algorithm 58 executed by theprocessor 54, each of the signals representing the scattered light received by the correspondingnodes 34 are evaluated to determine whether the light at thenode 34 is indicative of a predefined condition, such as smoke for example. With reference toFIG. 10 , a schematic diagram illustrating an example of a flow path for processing the signals generated by each of thenodes 34 is illustrated. As shown, the signal indicative ofscattered light 69 is parsed, shown atblock 70, into a plurality of signals based on their respective originatingnode 34. In the illustrated, non-limiting embodiment, background signals, illustrated schematically at 72, are subtracted from the data before the pulse features are evaluated for each of the individual signals. Through integration, pulse compression, and/or feature extraction, shown atblock 74, one or more characteristics or features (pulse features) of the signal may be determined. Examples of such features include, but are not limited to, a peak height, an area under a curve defined by the signal, statistical characteristics such as mean, variance, and/or higher-order moments, correlations in time, frequency, space, and/or combinations thereof, and empirical features as determined by deep learning, dictionary learning, and/or adaptive learning and the like. - In an embodiment, the time of flight record is parsed and features are extracted. The time of flight record can cover a period of time. For example, a time of flight record can record light intensity over 0.001 -1,000,000 nanoseconds, 0.1-100,000 nanoseconds, or 0.1-10,000 microseconds. The features extracted from the signal can include, but are not limited to height, full width at half maximum, signal pick up time, signal drop off time, group velocity, integration, rate of change, mean, and variance for example.
- Through application of the data processing, illustrated schematically at
block 76, the features may then be further processed by using, for example, smoothing, Fourier transforms or cross correlation. In an embodiment, the processed data is then sent to the detection algorithm atblock 78 to determine whether or not the signal indicates the presence and/or magnitude of a condition or event at a correspondingnode 34. This evaluation may be a simple binary comparison that does not identify the magnitude of deviation between the characteristic and a threshold. The evaluation may also be a comparison of a numerical function of the characteristic or characteristics to a threshold. The threshold may be determined a priori or may be determined from the signal. The determination of the threshold from the signal may be called background learning. Background learning may be accomplished by adaptive filtering, model-based parameter estimation, statistical modeling, and the like. In some embodiments, if one of the identified features does not exceed a threshold, the remainder of the detection algorithm is not applied in order to reduce the total amount processing done during the detection algorithm. In the event that the detection algorithm indicated the presence of the condition at one ormore nodes 34, an alarm or other fire suppression system may, but need not be activated. It should be understood that the process for evaluating the data illustrated and described herein is intended as an example only and that other processes including some or all of the steps indicated in the FIG. are also contemplated herein. - The evaluation may also advantageously employ classifiers including those that may be learned from the signal via deep learning techniques including, but not limited to deep neural networks, convolutional neural networks, recursive neural networks, dictionary learning, bag of visual/depth word techniques, Support Vector Machine (SVM), Decision Trees, Decision Forests, Fuzzy Logic, and the like. The classifiers may also be constructed using Markov Model techniques, Hidden Markov Models (HMM), Markov Decision Processes (MDP), Partially Observable MDPs, Markov Decision Logic, Probabilistic Programming, and the like.
- In addition to evaluating the signals generated from each
node 34 individually, theprocessor 54 may additionally be configured to evaluate the plurality of signals or characteristics thereof collectively, such as through a data fusion operation to produce fused signals or fused characteristics. The data fusion operation may provide information related to time and spatial evolution of an event or predetermined condition. As a result, a data fusion operation may be useful in detecting a lower level event, insufficient to initiate an alarm at any of thenodes 34 individually. For example, in the event of a slow burning fire, the light signal generated by a small amount of smoke near each of thenodes 34 individually may not be sufficient to initiate an alarm. However, when the signals from the plurality ofnodes 34 are reviewed in aggregate, the increase in light returned to the lightsensitive device 38 frommultiple nodes 34 may indicate the occurrence of an event or the presence of an object not otherwise detected. In an embodiment, the fusion is performed by Bayesian Estimation. Alternatively, linear or non-linear joint estimation techniques may be employed such as maximum likelihood (ML), maximum a priori (MAP), non-linear least squares (NNLS), clustering techniques, support vector machines, decision trees and forests, and the like. - As illustrated and described above, the
processor 54 is configured to analyze the signals generated by at least onelight sensing device 38 relative to time. In another embodiment, the detection algorithm may be configured to apply one or more of a Fourier transform, Wavelet transform, space-time transform, Choi-Williams distribution, Wigner-Ville distribution and the like, to the signals to convert the signals from a temporal domain to a frequency domain. This transformation may be applied to the signals when thenodes 34 are being analyzed individually, when thenodes 34 are being analyzed collectively during a data fusion, or both. - The relationship between the light scattering and the magnitude or presence of a condition is inferred by measuring a signal's causality and dependency. As an example, the measure of a causality utilizes one or more signal features as an input and determines one or more outputs from a calculation of a hypothesis testing method, foreground ratio, second derivative, mean or Granger Causality Test. Similarly, one or more signal features may be used as an input to evaluate the dependency of a signal. One or more outputs are selected from a calculation of a correlation, fast Fourier transform coefficients, a second derivative, or a window. The magnitude and presence of the condition is then based on the causality and dependency. The magnitude and presence of a condition may be calculated utilizing one or more evaluation approaches: a threshold, velocity, rate of change or a classifier. The detection algorithm may include utilizing the output from the calculation causality, dependency or both. This is used to indicate the presence of the condition at one or
more nodes 34 and initiate a response. - Because the frequency of smoke varies within a small range, such as from about 0.01 Hz to about 10 Hz for example, evaluation of the signals with respect to frequency may effectively and accurately determine the presence of smoke within the predetermined space 82. The detection algorithm may be configured to evaluate the signals in a fixed time window to determine the magnitude of the frequency or the strength of the motion of the smoke. Accordingly, if the magnitude of a frequency component exceeds a predetermined threshold, the detection algorithm may initiate an alarm indicating the presence of a fire. In an embodiment, the predetermined threshold is about 10 Hz such that when the magnitude of the optical smoke frequency exceeds the threshold, smoke is present.
- In an embodiment, the
algorithm 58 is configured to distinguish between different events or conditions based on the rate of change in the light scattered by the atmosphere near thenode 34 and received by one or more of thenodes 34 over time. With reference toFIGS. 11A and 11B , graphs of the signals recorded from anode 34 over time with respect to different events are illustrated.FIG. 11A indicates the change in the light signal received by anode 34 as a person walks through the area being monitored by thenode 34. As shown in the graph, the movement of a person appears as steps having varying magnitudes.FIG. 11B , which represents the detection of smoke from a smoldering fire, appears graphically as a much continuously changing signal having an accelerating increase in the change in light signal received by anode 34 over time. It should be understood that the graphs illustrated are examples only. Further, each predefined event detectable by thedetection system 20 may have one or more unique parameters associated therewith. - To reduce the noise associated with each signal, the
light emitting device 36 may be modulated such that thedevice 36 is selectively operated to generate modulated light in a specific pattern. In an embodiment, the light within the pattern may vary in intensity, width, frequency, phase, and may comprise discrete pulses or may be continuous. The specific pattern of light may be designed to have desirable properties such as a specific autocorrelation with itself or cross-correlation with a second specific pattern. When the light is emitted in a specific pattern, the light scattered back to a correspondinglight sensing device 38 should arrive in the substantially same pattern. Use of one or more specific and known patterns provides enhanced processing capabilities by allowing for thesystem 20 to reduce overall noise. This reduction in noise when combined with the signal processing may result in an improved signal to noise ratio and the total number of false events or conditions detected will decrease. Alternatively, or in addition, the device sensitivity may be improved thereby increasing the limits of thedetection system 20. Similarly, by crosscorrelating one or more second patterns, specific causes of transmitted or reflected signals may be distinguished, e.g. by Bayesian estimation of the respective cross-correlations of the received signal with the one or more second patterns. - In addition, modulation of the light signal emitted by the
light source 36 may provide improved detection by determining more information about the event or condition causing the scatter in the light signal received by thenode 34. For example, such modulation may allow thesystem 20 to more easily distinguish between a person walking through the designated area adjacent a node, as shown inFIG. 11A , and a smoldering fire adjacent thenode 34. - Referring now to
FIG. 12 , in some embodiments thesystem 20 includes one or moreoptical enhancement devices 80, such as a bandpass filter, a polarizer, an antireflective coating, a wave plate, and/or other optical features to reduce interference from non-event signals, or other non-desired signals, such as ambient light from either sunlight or lighting in the space, or from solid objects in the predetermined space 82. Further, theoptical enhancement devices 80 may be utilized to reduce undesired wavelengths and/or intensities transmitted from thelight source 36. Theoptical enhancement 80 is placed in thesystem 20 downstream of thelight source 36, in some embodiments a laser diode, and upstream of the lightsensitive device 38, in some embodiments the photodiode. Theoptical enhancement device 80 is placed so that light scattered and reflected back to the lightsensitive device 38 is passed through theoptical enhancement device 80 to filter or differentiate events or other conditions to be sensed from other signals due to, for example, ambient light, solid objects, bugs, dust, or water vapor. - As shown in
FIG. 12 , in some embodiments theoptical enhancement 80 is located at the lightsensitive device 38 and/or is a component of, integral to or embedded within the lightsensitive device 38. Further, the lightsensitive device 38 may be configured such that theoptical enhancement device 80 is readily removable and/or replaceable with anotheroptical enhancement 80 to filter or disseminate different conditions in the scattered/reflected signal. - While in the embodiment of
FIG. 12 , theoptical enhancement device 80 is located at the lightsensitive device 38 or embedded in the lightsensitive device 38, in other embodiments theoptical enhancement device 80 is located at other locations, such as at thenode 34 as shown inFIG. 13 . This allows for node-specific placement ofoptical enhancement devices 80 such that differentoptical enhancement devices 80 may be placed atdifferent nodes 34. Further, in some embodiments, combinations ofoptical enhancement devices 80, such as combinations of bandpass filters and polarizers, may be utilized to filter or disseminate certain conditions of the scattered/reflected light. Further, insystems 20 where thenodes 34 include two ormore cores optical enhancements 80 may be located at anindividual core cores - Referring now to
FIG. 14 , in some embodiments thesystem 20 includes focusing or expanding optical elements to increase range, sensitivity or field of view of thedetection system 20 in detecting smoke/gas or other conditions or events. A focusing optical element can be placed at the node or between the control system and fiber harness to increase range and sensitivity by converging or collimating light. Also, an expanding optical element can be placed in similar locations to increase the field of view of the node by diverging the light. By way of example, optical elements may include mirrors, focusing lenses, diverging lenses, and diffusers, along with the integration of antireflective coatings on the optical elements or components thereof. - As shown in
FIG. 14 , the optical elements may be one or more lenses 84 located at thenode 34. The lens 84 reduces divergence of the outgoing beam transmitted from thelight source 36, while also increasing the amount of scattered light accepted by thenode 34 for transmission to the lightsensitive device 38. In some embodiments, the lens 84 is fused to the end ofcores node 34 to reduce scattering of the light off of the lens 84 face, thereby enhancing light collection efficiency of thenode 34. Further, in some embodiments,cores cores - Referring now to
FIG. 15 , in some embodiments the optical elements may include a parabolic mirror 86 located at thenode 34. The parabolic mirror 86 is located offangle relative to a node axis 88. As with the lens 84, the parabolic mirror 86 reduces divergence of the outgoing beam transmitted from thelight source 36, while also increasing an amount of scattered light accepted by thenode 34 for transmission to the lightsensitive device 38. In some embodiments, the parabolic mirror 86 is configured to rotate about a rotational axis during operation of thesystem 20 to further increase a coverage area of thenode 34. - In some embodiments, both lens 84 and mirror 86 may be utilized at
node 34. Further, while in the embodiments illustrated inFIGs. 14 and15 optics are utilized at eachnode 34, in other embodiments, optics may be utilized only at selectednodes 34 to provide their benefits to the selectednodes 34, such as increasing detection range at selectednodes 34 due to, for example, constraints in placement ofnodes 34 in the protected space. In other embodiments, the optical elements can be placed at thelight source 36 or light sensitive device to enhance thedetection system 50. - In addition to smoke or dust, the
system 20 may be utilized to monitor or detect pollutants such as volatile organic compounds (VOC's), particle pollutants such as PM2.5 or PM10.0 particles, biological particles, and/or chemicals or gases such as H2, H2S, CO2, CO, NO2, NOs, or the like. Multiple wavelengths may be transmitted by thelight source 36 to enable simultaneous detection of smoke, as well as individual pollutant materials. For example, a first wavelength may be utilized for detection of smoke, while a second wavelength may be utilized for detection of VOC's. Additional wavelengths may be utilized for detection of additional pollutants, and using multiple wavelength information in aggregate may enhance sensitivity and provide discrimination of gas species from false or nuisance sources. In order to support multiple wavelengths, one or more lasers may be utilized to emit several wavelengths. Alternatively, the control system can provide selectively controlled emission of the light. Utilization of thesystem 20 for pollutant detection can lead to improved air quality in the predetermined space 82 as well as improved safety. - In some embodiments, such as shown in
FIG. 16A , thefiber optic branches 32 are each operably connected to thefiber harness backbone 31, which may only include a single fiber optic core, via acoupling 132. In some embodiments, thecoupling 132 is one of a splice connection, a fused connection or a solid state switching device. Utilizingcouplings 132 allowsnodes 34 to be added to thefiber harness 30 after installation of thefiber harness 30, or removal or relocation of thenodes 34 once thefiber harness 30 is installed. Thecouplings 132 therefore increase flexibility of thefiber harness 30 and thesystem 20. - In another embodiment, such as shown in
FIG. 16B , a firstfiber optic core 40 is operably coupled to afirst node 34, while asecond node 34 is operably coupled to a secondfiber optic core 42. In such embodiments, the firstfiber optic core 40 is utilized for transmission of light from thelight source 36, while the secondfiber optic core 42 receives scattered light and conveys the scatter light to the lightsensitive device 38. In some embodiments, afirst coupling 132a coupling the firstfiber optic core 40 to thefirst node 34 is the same as asecond coupling 132b coupling the secondfiber optic core 42 to thesecond node 34, while in other embodiment thefirst coupling 132a is different from thesecond coupling 132b. - Further, as an alternative to or in addition to the splice connection, fused connections, one or more solid state switching devices,
optical amplifiers 96 may be placed along thefiber harness 30 to amplify signals proceeding through thefiber harness 31. Theoptical amplifier 96 may be located, for example as shown inFIG. 17 , betweennodes 34, or between thelight detection device 38 and thefiber harness 30. Further, in some embodiments, coupling 132 may be located at other locations along thefiber harness 30, for example, between thefiber harness 30 and thelight source 36, and/or between thefiber harness 30 and the lightsensitive device 38. - Referring now to
FIG. 18 , thecontrol system 50 is configured for multiple inputs and/or multiple outputs for communication of information through thefiber optic cables 28 and thenodes 34. In some embodiments, the multiple inputs and outputs may include aninternet connection 140, a building network ormanagement system 142, and/or afire panel 134 of the building or enclosed space. Thefire panel 134 is configured for communications with, for example, a fire department, and/or is configured to transmit alarms through the building or space in the event of detection of smoke, fire or other substance by thesystem 20. In the embodiment shown inFIG. 18 , thefiber optic cables 28 are further utilized for the communication of alarms, alerts and other information, such as system diagnostic information through the building. Thecontrol system 50 is able to both measure the condition in the predetermined area 82 and provide communication. For example, once thecontrol system 50 determines that a condition is present based on detection signals received from one ormore nodes 34, thecontrol system 50 transmits one or more alarm signals from thefire panel 134 alongfiber optic cables 28 to one or more alarm units 138 in the building or space which initiate an alarm or alert based on the received alarm signals. Thecontrol system 50 is able to do this in afiber optic harness 30 by combining frequency and amplitude modulation of the light. In some embodiments, the alert or alarm is an audible sound or sounds, while in other embodiments the alert or alarm is a light, or a combination of light and sound. Further, thecontrol system 50 may be configured to send and/or receive communication through thefiber optic cables 28 and thenodes 34 to communicate with one or more building infrastructure or local devices in the space via modulated light transmitted along thecables 32. In some embodiments, this communication is via Li-Fi protocol. - Referring now to
FIG. 19 , shown is anenclosure 122, for example, a server housing, with one or moreelectronic components 124 located therein. Adetection system 20 is installed in theenclosure 122, along with asuppression system 126. Thesuppression system 126 may include, for example, asuppressant supply 128 and one or moresuppressant outlets 130 located at, for example,nodes 34 of thedetection system 20. Thedetection system 20, thesuppression system 126 and the one or moreelectronic components 124 are connected to thecontrol unit 52 of thedetection system 20. In the event of detection of fire or smoke at anode 34 of thedetection system 20, thecontrol unit 52 triggers thesuppression system 126 to activate thesuppressant outlet 130 at thenode 34 location to provide localized suppression in theenclosure 122. Further, thecontrol unit 52 may command powering down ofelectronic components 124 in thenode 34 region to prevent further damage to the particularelectronic components 124. Localized detection and suppression such as described herein viadetection system 20 andsuppression system 126, provides protection ofelectronic components 124 from fire and smoke, while localizing suppression to protect such components not subjected to fire and smoke from exposure to suppressant, reducing damage to those components and further reducing cost and expense of suppressant cleanup after an event. - Referring now to
FIG. 20 , shown is a schematic view of anaircraft 200. Theaircraft 200 includes afuselage 202 withwings 204 extending therefrom. Further, theaircraft 200 includes one or more compartments, i.e. the predetermined area, at which it is desired to provide fire, smoke and/or heat detection capabilities. These compartments may include acargo bay 206, alavatory 208, anavionics bay 210 or the like. One skilled in the art will readily recognize that the listed compartments are exemplary and that the present disclosure may be readily applied to other compartments of theaircraft 200. - Embodiments of
detection system 20 are installed in theaircraft 200 to detect fire, smoke and/or heat at thecompartments FIG 20 , afiber harness 30 is connected to acontrol system 50 at aport 212 and can have one or morefiber optic cables 28 extending to thecompartments fiber optic cables 28 or fiber optic cores in thefiber harness 30 will be used for smoke/fire detection, while others are used for temperature measurements. However, thecontrol system 50 is utilized to evaluate scattered light from thefiber harness 30 for both smoke detection and temperature/overheat detection. - A comparison of the light transmitted by the
light source 36 and scattered light received at the lightsensitive device 38 will indicate whether or not changes in the atmosphere adjacent to thenode 34 are present. For example, the presence of smoke or other particles in the atmosphere will cause the light emitted through the node to scatter outside of the fiber. Although thedetection system 20 is described as using light scattering to determine a condition or event, embodiments where light obscuration, absorption, and fluorescence is used in addition to light scattering are also within the scope of the disclosure. - A first
fiber optic cable 28 is utilized to monitor a compartment or area for smoke and/or fire conditions, while a secondfiber optic cable 28 is utilized to monitor a compartment or area for temperature conditions. Between theport 212 and thenode 34, the firstfiber optic cable 28 extends into or through one or more compartments of interest for thedetection system 20 to monitor or detect smoke in the compartments Similarly, between theport 212 and thenode 34, the secondfiber optic cable 28 extends into or through one or more compartments of interest for thedetection system 20 to monitor or detect overheat conditions in the compartments. The second fiber optic cable can also be extended through one or more compartments in a loop. - While smoke/fire detection is done by observing the scattered light near the node 34 (not inside the fiber), the temperature is monitored by analyzing the internal scattering in the fiber. An increase in the temperature of the ambient air surrounding the
fiber optic cables 28 will cause Rayleigh and Raman scattering inside the fiber optic core(s). This internal scattering can then be correlated to a temperature of the ambient air near thecore control system 50. Further, in some embodiments, the outbound light from the light source 26 may be repeated at multiple wavelengths to reduce false alarms, provide health monitoring through strain and temperature sensing, end of life conditions or environmental health monitoring of volatile organic compounds (VOCs). - While the disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
Claims (11)
- A method of monitoring fire conditions within an aircraft structure comprising:providing a first fiber optic cable terminating at a node disposed to monitor a smoke condition at one or more predetermined areas of the aircraft structure;providing a second fiber optic cable arranged to monitor a temperature condition at one or more predetermined areas of the aircraft structure;connecting the first fiber optic cable and the second fiber optic cable to a control system via a port, the control system comprising a light source and a light sensitive device;transmitting light from the light source (36) through the first fiber optic cable;transmitting light from the light source (36) along the second fiber optic cable (28);receiving scattered light from the first fiber optic cable (28) and the second fiber optic cable (28) at the control system (50) via the light sensitive device;determining by the control system at least one of the presence and magnitude of the smoke condition by analyzing light scattered near the node outside the first fiber optic cable; anddetermining by the control system the temperature condition at the one or more predetermined areas by analyzing the scattered light that has been internally scattered at one or more fiber portions of the second fiber optic cable (28).
- The method according to claim 1, wherein the light source (36) is selectively operated to transmit the light signal.
- The method according to claim 1or 2, further comprising selectably changing a wavelength of the transmitted light.
- The method according to any preceding claim, further comprising converting the scattered light signal into corresponding electrical signals for evaluation by a control unit (50).
- A system (20) for monitoring fire conditions within an aircraft structure (200) comprising:a fiber harness (30) comprising a first fiber optic cable (28) terminating at a node (34) disposed to monitor a smoke condition at one or more predetermined areas of the aircraft structure and a second fiber optic cable (28) arranged to monitor a temperature condition at one or more predetermined areas of the aircraft structure; anda control system (50) operably connected to the fiber harness (30) at a port (212), the control system comprising:a light source (36) for transmitting a light signal along the first fiber optic cable (28) and the second fiber optic cable (28);one or more light sensitive devices (38) configured to receive light from the first fiber optic cable (28) and the second fiber optic cable (28); anda control unit (50) of the control system configured to:determine at least one of the presence and magnitude of the smoke condition by analyzing light scattered near the node outside the first fiber optic cable; anddetermine the temperature condition at the one or more predetermined areas by analyzing the scattered light that has been internally scattered at one or more fiber portions of the second fiber optic cable.
- The system (20) according to claim 5, wherein measuring the temperature further comprises determining an overheat condition.
- The system (20) according to claim 5 or 6, wherein the one or more light sensitive devices (38) comprises a first light sensitive device (38) configured to receive light from the first fiber optic cable (28) and a second light sensitive device (38) configured to receive light from the second fiber optic cable (28).
- The system (20) according to claim 5, wherein the control unit (50) is operably coupled to the light source (36) to selectively control emission of light from the light source (36).
- The system according to any one of claims 5-8, wherein the light sensitive device (38) is a photodiode.
- The system according to any one of claims 5-9, wherein the light sensitive device (38) is configured to convert the scattered light signal received at the control system (50) into an electrical signal receivable by the control unit (50).
- The system according to any one of claims 5-10, wherein the first fiber optic cable (28) defines a plurality of nodes (34) arranged within the aircraft structure (200).
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CN109085152A (en) * | 2018-10-18 | 2018-12-25 | 吉林大学 | A kind of multichannel optical fiber formula gas Raman scatterometry system |
CN111696294A (en) * | 2019-03-11 | 2020-09-22 | 华龙国际核电技术有限公司 | Operation terminal |
GB2592709B (en) * | 2019-06-27 | 2023-03-01 | Carrier Corp | Smoke detection and localization based on cloud platform |
CN111028460A (en) * | 2019-12-06 | 2020-04-17 | 河南师范大学 | Cavity ring-down double-channel smoke temperature fire detection device adopting time-delay frequency division technology |
CA3115486A1 (en) | 2020-04-17 | 2021-10-17 | Oshkosh Corporation | Thermal management sensors |
US11551534B2 (en) * | 2020-04-17 | 2023-01-10 | Oshkosh Corporation | Thermal management controls |
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