The invention described herein relates to an alarm detection system. In particular, the invention relates to a system for use on seafaring vessels which monitors the state of alarm devices onboard the vessels in order to provide better response times following activation of an alarm device.

Most domestic and commercial buildings will nowadays have some type of integrated alarm system fitted. Smoke and CO detectors are, for example, legally required to be fitted within rental properties and workplaces in most countries and the use of burglar alarms is now also widespread. Although a loud sound can be useful in deterring a burglar or alerting neighbours or residents, in a case where the home owner is not in or if no one is present in the workplace the alarm may be useless unless further action can be taken. In some cases, such systems are configured to automatically alert emergency services or to send a text message to a remote location when an alarm is triggered.

Onboard marine vessels there are particular considerations in terms of how such an alarm detection system might operate. On a ship, wireless communication systems may not always be available, and so improving the way in which data is processed and minimising the amount of data required to be transferred is tantamount. Systems suitable for use in the home on land may not function in a marine environment because of a reliance on the immediate transfer of data to a remote location.

Integration of alarm detection systems with existing alarm systems onboard seafaring vessels is also complex and expensive. The system described below provides a simple and cost-effective solution which simplifies the detection of an alarm event, thus reducing processing requirements and ensure that crew members can be alerted quickly.

According to a first aspect of the present invention there is provided an alarm detection system for a vessel comprising: one or more processing units comprising a sensor configured to detect electrical current in a wire coupled to an alarm device and a processor configured to accept a signal from the sensor as input and to determine from the signal whether the alarm device is activated; and a central control unit coupled to the one or more processing units, wherein the processing units are each configured to send an indication to the central control unit when it is determined that the alarm device has been activated. The detection system can provide a reliable indication of whether or not an alarm has been triggered without requiring collocation with the alarm device itself. The system requires little processing power, has few data transfer requirements, and can work even if, for some reason, the alarm device itself malfunctions and cannot be heard or seen by personnel in the vicinity. This may be the case if the speaker connected to or comprised within an alarm is not working properly, for example. The sensor may be capable of detecting either the change from no current flowing in the wire to a current flowing, or more generally a change in the current flowing in the wire such as a step up in current from one level to another. In some cases the lower level current may be detected by the sensor due to current flowing through nearby wires, rather than the wire associated with the alarm. In such a case it may be preferable that a low level current not detected as alarm data. Reference to an alarm that is activated is to an alarm that has been activated by an event (such as the detection of a threshold level of smoke or a threshold temperature) and that is currently sounding.

In embodiments, the processor is configured to analyze the signal from the sensor by matching to a database of signal patterns to determine whether the alarm device has been activated.

In embodiments, if it is detected that an alarm has been activated the processor is configured to use the pattern matching process to determine the alarm type of the alarm device which has been activated. This can be done in a fairly straightforward manner using properties of the signal received from the sensor. The database of patterns can be updated as needed to suit the configuration of the larger alarm detection system.

In embodiments, the processor is configured to normalize the signal to a square wave before determining whether the alarm device is activated and/or determining the alarm type of the alarm that has been activated using one or more properties of the square wave.

In embodiments, the one or more properties comprise one or more of the width of the peaks of the square wave, the maximum amplitude of the peaks, and the distance between adjacent peaks. The use of a signal normalized to a square wave is an effective way to simplify the matching process and can still produce accurate results in terms of successfully detecting and/or identifying an alarm event.

In embodiments, the processor comprises machine learning software and the signal from the sensor, possibly normalized to a square wave signal, is classified using the machine learning algorithm into ambient class or alarm class data to determine whether the alarm device has been activated. Ambient class data in this case may simply correspond to no signal being received from the sensor. Machine learning software as part of the central unit or the processing unit can also be used to classify the signal from the alarm or the simplified square wave signal as belonging to a particular alarm. The machine learning software may be trained prior to use of the system as a detection system using training data which can match most efficiently the patterns of signals passing to the alarms. Further processing will then comprise inputting the square wave signal to the machine learning software or algorithm which will then classify it as corresponding to alarm class or ambient data, and which may further classify it as corresponding to a particular alarm (general, MOB, or fire, etc).

In embodiments, the sensor is an induction sensor comprising one or more of a Hall effect sensor, a flux gate sensor, and a magneto-resistive sensor. In embodiments, the sensor is configured to detect an electromagnetic field caused by the current flow through a wire. When a current flows through the wire to an alarm, which will generally be the case only in the event that the alarm is triggered, a magnetic field is created around the wire which may induce a detectable current in the sensor circuit. The sensor may alternatively, or in addition, detect a temperature change or resistance in the wire caused by the current flowing therethrough. The sensor can alternatively or additionally detect a change in magnetic field around the wire caused by a change in current flow or a sound produced by the presence of current in the wire or a change in current flow.

In embodiments, the alarm detection system comprises two or more processing units configured to detect current flowing through different wires. The wires may be connected to provide current to different alarms. The alarm detection system in such a case can be referred to as a distributed alarm detection system. The processing units may be located in separate areas of the vessel. Separate areas may also refer to processing units being separated by physical structures such as walls, i.e. not being within a direct line of sight of one another. In embodiments, the central control unit comprises a user interface and is configured to communicate the indication to the user via the user interface. The controller includes some means by which the indication can be directly communicated to a personnel member. This may be in the form of a display screen which may display a simple indication that an alarm has sounded, or which may show additional information about the type and location of the alarm, as well as information about the action to be taken in response. The control unit may be configured to collect data directly from each of the one or more processing units in the system (rather than via other units).

In embodiments, the one or more processing units comprise a processor and one or more sensors for detecting the current, and the one or more sensors are connected to the processor via wired or wireless communication means. The processor may be a simple embedded processor.

In embodiments, at least one activation profile is stored on the processing unit associated with the or each alarm class data and specifying an action, the activation profile being accessed when the software detects the associated alarm data thus causing the action to be performed.

In embodiments, the action comprises activation of a remote crew monitoring system. Obviously, knowledge of the whereabouts of crew members is paramount in case of emergency. This information can automatically begin to be collected and passed to a central unit as soon as an alarm is activated. Again, the amount of data that needs to be transferred during a normal situation is minimised since the crew monitoring system need not necessarily be active during these times.

In embodiments, the remote crew monitoring system comprises nodes configured to communicate via radio communication means both with mobile units to be carried by crew members and with a central crew monitoring control unit. The central crew monitoring control unit may be located in the same housing or in a different housing to the central control unit of the alarm detection system.

The invention will be described in more detail with reference to the figures in which:

Figure 1 shows an alarm detection system and alarm control system; and Figure 2 illustrates the process of alarm detection according to an example.

Figure 1 shows the components of an alarm detection system. The system includes a current sensor 2 which is located in the vicinity of a powerline 4 carrying current to activate an alarm device 6. Raw data from the current sensor is sent to a signal processing module 8 which may convert the signal into a binary signal (high or low, 1 or 0) such as a square wave signal. The square wave may represent an AC or DC current to which thresholding has been applied. The processed signal (or the raw signal) is passed to a pattern matching module 10, which is operable to match the signal received to a database of signals in order to determine whether an alarm has sounded, and if so which type of alarm has sounded. The pattern matching module can be dispensed with and a simple threshold applied to the signal to determine if the current flow within the powerline is above a particular level. The simple presence or absence of a signal from the sensor can also inform whether the alarm device is active. Pattern matching or thresholding using the processed square wave signal is simpler, but the unprocessed sensor signal can also be used, in which case the raw signal is used to determine whether the alarm device is active. As an alternative to it being carried out by the processing unit, the determination of whether an alarm has sounded, and the processing software required for this, may be located at the central control unit or another unit within the system. Sensor data may be sent to this alternative unit and processed there in order to determine whether an alarm has sounded.

If it is detected that an alarm has sounded or is active, then an indication will be sent to a central control module or to a crew member or a select set of crew members. The indication may comprise information relating to the type of alarm and/or what actions need to be taken. Other monitoring and control systems on the vessel may be affected by the detection of an alarm event. These may move from an energy preservation mode, used normally, to a higher power mode in which more information is sent or in which information is sent more often to ensure that the onboard systems (such as a crew monitoring system) are operating at full capacity.

The sensor can be any detection device capable of detecting, either directly or indirectly, a current flowing through the wire servicing an alarm. A sensor may detect the electromagnetic field created by the flow of current through the wire, for example. In such a case, the sensor may detect either AC or DC current, or may be capable of detecting both. Suitable devices for use as the sensors are Hall effect sensors, flux gate sensors, and magneto-resistive sensors. Sensors can be located near to the wires or may comprise a sensing loop through which the wire passes.

The system may include a number of sensors, each of which may be associated with a wire configured to carry current to a particular alarm device onboard the ship. Each sensor may be associated with its own processing unit so that the processing units are distributed around the ship and are collocated with the sensors themselves. Alternatively, sensors may be distributed, but more than one sensor or all of the sensors in the system may send raw data to a single processing unit. Sensors may be located particularly in rooms or areas of the ship where the wiring to alarms is located, such as on the bridge, or in an area where an emergency situation is more likely to occur. The sensors may therefore be associated with different wires but may be located fairly near to each other. The system also includes a central control unit located on the ship and connected to the processing units.

Sensors can be located so as to be able to detect current from more than one wire. In this case it may be possible to distinguish between current in one wire and in another using pattern matching in which case the system will include fewer parts. Alternatively, It may not be necessary to distinguish between current in more than one wire associated with the single sensor. Current in either or any of the wires will cause an alarm detection to be registered and a notification to be sent to a control unit to alert crew.

Communication between the processing units and control unit may be by wireless means or via powerline communication or by another wired form of communication, which will prevent interruption to wireless connection onboard a vessel from affecting the performance of the detection system. The control unit and the one or more processing units of the system may be collocated and may be located within the same housing in some embodiments.

The processing unit may also comprise a software module, a communication module, and the appropriate hardware to support the desired software and functionality. The processing unit will, in some examples of the system, also analyse the signals received from the sensors in order to determine which alarm or alarm event the signals belong to. This process may use machine learning capabilities to enable the functionality of the software to improve over time. The detection unit can also be configured to select and activate an activation profile associated with the alarm signal if an alarm signal is detected.

The current flowing to the alarm that has been activated is detected by the sensor and in most cases will be identified by the software as relating to that particular alarm. The determination of which alarm the signal relates to may simply be based on which sensor detects a signal, since sensors are each associated with a wire leading to a particular alarm. This is a very low-cost way of being able not only to detect that an alarm has sounded, but to determine which of a number of alarms this is.

The sensor signal sent to the pattern matching, thresholding, or machine learning software may, in some embodiments, include information about the amplitude and frequency of an AC signal in the wire, rather than indicating only whether or not a current is present. In such a case the signal, which will be either continuous or converted to a square wave signal by the processor, can be matched to a database of signals, as for previous embodiments described above, to determine which type of alarm has been triggered. In such a case, the pattern matching process can be similar or the same, but the raw data will be different (i.e. will be in the form of a square wave). The patterns within the database to which the signal is to be matched can also be in the form of square waves, or can represent typical values for one or more parameters of a signal associated with an alarm, or can represent raw signals associated with each alarm event. The matching process may comprise the calculation of a value representing a correlation between the input signal and each of the signals in the database, for example. The input and database signals may alternatively simply be subtracted one from another to determine which of the database signals is closest to the input.

Figure 2 shows a flowchart of the alarm detection process in one example. The sensor is configured to sense current in a powerline to an alarm device which will flow when the alarm device is activated. Signals from the sensor (which may indicate that no current is flowing through the wire) are sent to a processor which converts the signal into a square wave to simplify pattern matching. The converted signal is compared to a database of signal patterns to find a match which will indicate whether the signal relates to an alarm event or not and may indicate what type of alarm device has been activated using information in the signal. If an alarm event is detected, then a notification is sent to a control unit which relays information about the alarm event to one or more crew members so that the appropriate action can be taken. The alarm event may be associated with an activation profile after pattern matching, and the activation profile can determine which crew members are to be alerted and which other actions are taken in response to the detection, as described in more detail below.

The signal for a particular alarm that is recognised by the processing software may be linked to an activation profile which details various actions that should be performed by the system in the event that the alarm event is detected. The activation profile may cause these actions to be performed automatically on activation of the profile. The activation profile linked to a particular alarm or alarm type, and to a particular action, is then saved as part of a database of activation profiles to be installed on (or already created on) the relevant processing unit along with the pattern matching module if present. Activation profiles will depend on the alarms to be detected by the processing unit at issue and will thus vary depending on which wires the sensor is configured to monitor within the ship or in the building. Activation profiles may be linked specifically to a type of alarm and may be activated in response to detection of an alarm signal relating to that particular alarm type. In this case separate activation profiles are associated with each of a general alarm, a fire alarm, and a man overboard alarm. Different activation profiles may be associated with emergency alarms in general and with other types of alarms (those which indicate a change in environment such as a rise in temperature above a particular level, for example).

The detection unit itself (which is usually collocated with the powerline to the alarm device and which comprises the sensor, a processor, and communication means to send an indication to the central control unit) includes the processing capability and required information to determine that an alarm has been activated and generally also to access an activation profile associated with that particular alarm. Select information required by crew members can then be sent to the central control unit and relayed to the crew.

In some embodiments, the software will be configured to access an activation profile associated with the triggering of a particular alarm. In response the software may forward only select information included in the activation profile, by wired or wireless connection, to the control unit and/or to another location. The select information may consist only of an action to be taken by a particular crew member or may additionally comprise some information about the situation, such as location of the triggered alarm and the type of alarm. Alternatively, information about immediate actions to be taken by various crew members may be forwarded initially, and additional information can be sent at a later stage once the emergency situation has been dealt with. This way information overload is avoided, and the amount of data required to be transported over the network initially is reduced.

Processing in this type of system in some circumstances is distributed in that it takes place at the separate processing units which are each located in the vicinity of the wiring leading to at least one alarm. Only minimal information needs to be transmitted subsequently to enable the required actions to be taken and the system does not rely on transmission by wireless means. This can be of paramount importance on a seafaring vessel where wireless data transport may be available only intermittently.

The sensor can be configured to detect current passing along a cable which provides power to an alarm when the alarm is activated. If an alarm is activated, then current will flow along this cable and sensor signal data from the processing unit will reflect this. The processing software will receive an indication from the sensor that a current is present in the wire leading to an alarm and this will ultimately cause activation of the profile associated with the same alarm or alarm type. The sensor may work by induction, wherein the current in the adjacent powerline causes creation of a current in the sensor which can be measured or detected. This detection method will be possible because alarms generally operate using a simple circuit. Current is caused to run through the circuit using an activation switch, at which point the alarm will sound. In this case the processing unit need not be located in the vicinity of one or more alarms but should be located rather in the vicinity of the powerlines leading to those alarms. This provides for flexibility in terms of where the sensors can be placed and means that the system can work even if, for example, the speaker associated with an alarm is malfunctioning and the alarm sound cannot be heard.

In its simplest form, the system is required only to distinguish between the presence of current or absence of current in the wire. Knowledge of which wire the sensor is coupled to can allow the system to be informed immediately and with minimal additional processing which alarm of a number of alarms has sounded. The processing unit may simply comprise a sensor capable of detecting current running through the wire and an embedded processor, usually having a fairly low processing power which keeps cost and weight of the unit down as far as possible. Current may be detected via induction causing a corresponding flow of current in the sensor, for example. If only a binary outcome is required, the sensor and processor need only be configured to determine whether there is a current in the wire connected to the alarm or not. The processing unit sends a signal to the central controller in the event that current is detected (alarm on). Different wires may carry current on activation of different alarm circuits, which means that different alarms can be distinguished using this method simply by locating a number of sensors near to wires relating to the different alarms. If only one wire carries current for a number of alarms, then it will not be possible to determine which alarm has sounded in the case of a processor configured only to determine the presence or absence of a current in the wire. In this simple embodiment, a database of signals for comparison will usually not be required.

An alarm unit generates a pulse signal which causes the alarm sound to be switched on and off, or the pitch to be altered, for a specified duration or until the alarm circuit is switched off again manually. A single sensor may, in some cases, therefore be used both to detect the activation of an alarm and to determine which of a number of alarms or alarm types has been sounded. This is the case both if one wire is configured to carry current to a number of alarms, or if a single sensor is coupled to a number of wires for detecting current flowing therethrough. This capability may make use of the fact that different alarm sounds will be associated with different pulse signals. The pulse signal will determine for how long and with what frequency the alarm sounds. The same signal may also modify the pitch of the alarm sound. By a very basic analysis of the current within the alarm circuit, it is possible to distinguish between alarms. Additional processing capability may be included in the remote detection unit to allow the signal resulting from the detected current to be normalised and transformed to a square wave (signals below a certain level are attributed a first value and signals above this level are attributed a second value).

The resulting square wave can be easily matched to a database of signals relating to the different alarms, or to different subsets of alarms, within the system. Information regarding activation of a particular alarm signal (or a particular subset) can then be forwarded to the central control unit. Matching can be achieved by determining simple parameters of the square wave signal (or the signal itself) such as the width of peaks, height of peaks, distance between peaks, and so on. These can be matched to ranges corresponding to different alarms or alarm types within a database stored on the processing unit. Machine learning can be used to classify signals if a more tailored approach is desired.

A central hub for wiring to different alarms within a system may be located somewhere on the ship, such as on the bridge. The alarm detection system may be collocated with or located near to the wiring hub. In this way, a separate sensor can be coupled to each of the separate wires leading to each of the alarms present on the vessel to detect current flowing therethrough or to detect a change in the current flowing therethrough. When one or more of the sensors detects a current in its associated cable or wire, it may send a signal to a processing unit. A single processing unit can be used to accept signals from all of the sensors present in the system, or a number of processing units may be included in the system, such as one processing unit associated with each sensor. This may reduce the amount of processing required since it will not be necessary for any single processor to determine from which sensor a signal is received and then match this to a particular activation profile.

The software linked to a processing unit may start automatically during an emergency situation onboard a vessel. This may be in response to activation of a central alarm or activation of the system itself by a user, for example by pressing a button on the bridge or on a mobile unit carried by a crew member. Different alarms all around the ship will then begin to be monitored and where an alarm has been activated this will be recognised by the processing unit linked to that alarm. This will cause information about necessary actions or identifying the issue to be passed to the central unit or to specific areas of the ship or members of personnel. Information may also automatically be passed by the central control unit, or in some cases directly from the processing unit, to the crew member who has activated the alarm or system.

Actions linked to particular alarms in the activation profiles stored on each processing unit may be automatically executed once the activation profile is activated/accessed. In one embodiment, one of the actions carried out once the activation profile is accessed may comprise the switching on/activation of a crew monitoring system.

The crew monitoring system may work by way of radio tags on mobile units which are carried by each crew and/or passenger and which communicate with nodes to track the position of personnel onboard a vessel, preferably via radio communication. The mobile units may be capable of processing various sensor data which may inform as to whether a passenger has fallen overboard or is ill, for example, and such information can also be sent to the local node. Local nodes are coupled to a central control system, possibly by way of wired communication such as powerline communication. Such systems are particularly critical during an emergency situation and may only be activated as an action performed by the alarm detection system when an alarm is detected. Monitoring systems may be activated only for one or more nodes in the vicinity of the alarm that has been triggered. This helps to save power in a normal situation and ensures that the required information is available in an emergency.

On board a ship the most important alarms, which will typically all be present, are fire alarms, man overboard (MOB) alarms, and general alarms. The detection of the activation of any of these alarms by the alarm detection system may trigger the activation of the crew monitoring system. Each of these alarms, in addition, may result in a different activation profile wherein the crew are given different roles or are instructed to perform different actions, or wherein monitoring of crew in a specific area of the ship (such as an area close to the activated alarm or likely to be most affected by the cause of the alarm) is given priority. A different subsection of the crew or area of the vessel may also be monitored depending on the type of alarm that has been triggered or the location of that alarm. Information may be sent to and displayed on display devices carried by specific crew members, such as the captain or officers on duty who need to be alerted. This may be achieved by wireless or wired transmission from the central control unit or by wireless or wired transmission directly from the processing unit to the crew member. This may be, for example, to a mobile unit carried by the crew member or to a PC or display device to which they have access. The central control unit will generally be located on the bridge in order that it is easily accessible by senior ranking crew members at all times.

In an example for use on a marine vessel, the system may include a detection unit located on the bridge (which represents a secure location through which powerlines to alarm devices located around the ship will usually pass). The central control unit may be located on the bridge or in a separate area of the vessel, but it should be located in a place where crew members are able to respond to the information provided. Even if the crew members are able to hear the alarm themselves from the location of the control unit, it can take time to identify where the alarm has been sounded or to determine which alarm a particular sound corresponds to or what actions should be taken in response, so that the system helps to improve response times even in a situation where all units are collocated. As mentioned, simple processing is carried out at the processing unit and basic information provided to the central control to avoid the need for large amounts of data to be transferred.

The invention is particularly applicable to the maritime industry, such as on cruise ships, offshore vessels, and oil rigs, all of which face the same issues in terms of connectivity. It could, however, also be implemented in onshore infrastructures, where other types of alarm are used. The system can, for example, be used in a commercial or residential building with sensors connected to wiring for one or more alarms within the building and to a central control unit.