WO2014023715A1

WO2014023715A1 - Alarm system with objects operating both as sensors and as actuators

Info

Publication number: WO2014023715A1
Application number: PCT/EP2013/066441
Authority: WO
Inventors: Marco Pezzola; Elisabetta LEO
Original assignee: Hst S.R.L.
Priority date: 2012-08-08
Filing date: 2013-08-06
Publication date: 2014-02-13
Also published as: ITMI20121414A1; EP2883222B1; EP2883222A1

Abstract

A solution for alarming a structure is proposed. A corresponding anti-intrusion system detects the vibration of an object belonging to a structure and the alarm is given in the form of induced vibration of the same object. For example, the objects may be panels of a perimeter of a property, so that vibrations caused by burglars attempting to cross the fence are detected. After verification of the vibration detected (discrimination that vibration was not caused by weather conditions like rain or storm), an alarm is given by vibration actuators that are placed on the same perimeter elements as an alarm signal. Self-calibration is foreseen as historical data that can be logged and used to update detection thresholds (e.g. taking into account different background vibration during night and day).

Description

ALARM SYSTEM WITH OBJECTS OPERATING BOTH AS SENSORS AND AS

ACTUATORS

The solution according to one or more embodiments of the present invention generally relates to alarm systems.

Alarm systems are commonly used for alarming structures of various types. A typical example of alarm system is an anti-intrusion system for preventing intrusions by burglars, for example, in a dwelling.

The alarm system is based on sensors that detect alarm conditions (for example, an attempt of intrusion into the dwelling); typically, the alarm system comprises infrared sensors (which detect movements by measuring corresponding changes in temperature) and/or magnetic sensors (which detect openings of perimetral elements, such as doors and windows, through the moving away of corresponding magnets). The sensors are connected to a control unit, by means of wired or wire-less connections; the control unit recognizes the alarm conditions according to the signals collected by the sensors. The alarm system is also provided with actuators, which are activated whenever an alarm condition is detected. Typically, the actuators comprise a siren that emits an alarm sound (for example, to attract the attention of nearby people, and to frighten and make the burglars to flight); in addition, the actuators may also comprise a dialer, which transmits a registered alarm message to a series of pre-set telephone numbers.

Several types of alarm systems, more or less sophisticated, are available on the market. However, the known alarm systems are not entirely satisfactory.

Particularly, the sensors and the actuators are quite expensive; moreover, their installation requires relatively complex and lengthy operations. These components are very specific for the different applications, and therefore they may not be manufactured on a large scale. All of the above has a detrimental effect on the total cost of the alarm system.

Furthermore, the sensors and the actuators are quite fragile and easily subject to malfunctions, with a resulting reduction of reliability of the entire alarm system.

In any case, it is very difficult (if not impossible) to conceal the sensors and especially the actuators, so that they are in general immediately detectable; this facilitates the disconnection of the sensors and/or the actuators, and then of the alarm system (thereby reducing its effectiveness). The use of piezoelectric elements in alarm systems is also known. For example, EP-A-001 1451 (the entire disclosure of which is herein incorporated by reference) describes the use of piezoelectric elements as sensors; however, the above-mentioned drawbacks relating to the actuators remain unaffected.

Furthermore, US-A-4470040 (the entire disclosure of which is herein incorporated by reference) describes the use of a piezoelectric element both as sensor and as alarm generator. Particularly, this document proposes a battery-powered device, wherein a voltage generated by a piezoelectric element in response to a vibration automatically activates an oscillator that causes a vibration of the same piezoelectric element (causing it to emit a corresponding sound). However, this device is of limited application (for example, it is not suitable for anti-intrusion systems). Indeed, the sound that may be emitted by the piezoelectric element has low intensity (at most audible 10 m away); moreover, the automatic activation of the device does not allow discriminating actual alarm conditions from other events relating to normal conditions.

Piezoelectric elements may also be used to make panel-like microphones and/or speakers in entirely different applications (for example, for the playback of music), as described in EP-A-0847678, US-B-618 775, US-A-4751419 and US-B-6522760 (the entire disclosures of which are herein incorporated by reference).

In general terms, the solution according to one or more embodiments of the present invention is based on the idea of using one or more objects both as sensors and as actuators.

Particularly, one or more aspects of the solution according to specific embodiments of the invention are set out in the independent claims and advantageous features thereof are set out in the dependent claims, with the wording of all the claims that is herein incorporated verbatim by reference (with any advantageous feature provided with reference to a specific aspect of the solution according to an embodiment of the invention that applies mutatis mutandis to every other aspect thereof).

More specifically, an aspect of the solution according to an embodiment of the invention provides an alarm system with a set of sensors, processing means for recognizing an alarm condition according to an induced vibration detected by of at least one of the sensors, and a set of actuators for causing an alarm vibration in response to the recognition of the alarm condition, wherein each one of a set of objects is associated with at least one transducer for detecting the induced vibration of the object and for causing the alarm vibration of the same object.

Another aspect of the solution according to an embodiment of the invention provides an alarmed structure comprising such alarm system.

Another aspect of the solution according to an embodiment of the invention provides a corresponding method for alarming a structure.

Another aspect of the solution according to an embodiment of the invention provides a computer program for implementing such method (and a corresponding computer program product).

The solution according to one or more embodiments of the invention, as well as further features and the advantages thereof, will be best understood with reference to the following detailed description, given purely by way of a non-restrictive indication, to be read in conjunction with the accompanying drawings (wherein, for the sake of simplicity, corresponding elements are denoted with equal or similar references and their explanation is not repeated, and the name of each entity is generally used to denote both its type and its attributes - such as value, content and representation). In this respect, it is expressly intended that the figures are not necessary drawn to scale (with some details that may be exaggerated and/or simplified) and that, unless otherwise denoted, they are merely used to conceptually illustrate the structures and procedures described herein. Particularly:

FIG. l shows a pictorial representation of a structure in which the solution according to an embodiment of the invention may be applied,

FIG.2. shows an example of application of the solution according to an embodiment of the invention,

FIG.3 shows a detail of an alarm system according to an embodiment of the invention,

FIG.4 shows a principle block diagram of some components of the alarm system according to an embodiment of the invention,

FIG.5 shows the main software components that may be used to implement the solution according to an embodiment of the invention,

FIG.6A-FIG.6C show an activity diagram describing the flow of activities relating to an implementation of the solution according to an embodiment of the invention, and

FIG.7A-FIG.7G show various examples of application of the solution according to an embodiment of the invention.

With reference in particular to the FIG. l, a pictorial representation is shown of a structure 100 in which the solution according to an embodiment of the invention may be applied. Particularly, the structure 100 is a condominium with one or more buildings 105 (each one comprising several apartments); the buildings 105 are surrounded by a common area 1 10 (for example, a common garden). A fence 115 protects the entire common area 110; for this purpose, the fence 115 comprises a series of panels 120, which are arranged vertically side-by- side.

Passing to the FIG.2, it shows an example of application of the solution according to an embodiment of the invention,

An alarm system (and in particular an anti- intrusion system) 200 is used to prevent (or at least hinder) any intrusions into the condominium by burglars; for example, in the case at issue, the alarm system 200 alarms the fence 1 15 so as to protect it against any attempts to climb over it by the burglars who might enter the common area 1 10. For this purpose, the alarm system 200 comprises a set of sensors, each of which is used to detect a vibration; the vibration may be mechanical (for example, caused by a collision) and/or acoustical (for example, caused by a sound). The alarm system 200 also comprises a set of actuators, each of which is used to cause a (mechanical and/or acoustical) vibration.

In the solution according to an embodiment of the invention, as described in detail in the following, a same object (preferably a component of the structure to be alarmed) is used both as sensor (to detect the vibration of the object itself) and as actuator (to cause the vibration of the object itself). In the specific example shown in the figure, the object being used both as sensor and as actuator is each panel of the fence 1 15 (not visible in the figure). Therefore, the panel operates as sensor for detecting each vibration thereof that is caused by a burglar who is attempting to enter the common area 110; for example, this vibration may be of mechanical type when the burglar climbs over the fence 115 and/or of acoustical type when the burglar makes noises close to the fence 115. At the same time, the panel works as an actuator to cause a vibration thereof when the attempt of intrusion is detected; for example, this vibration may be of mechanical type to frighten the burglar who is climbing over the fence 115 and/or of acoustical type to attract the attention of neighbors and to make the burglar to flight.

In the specific example at issue, the fence 1 15 is split into sectors (three of which, denoted with the references 1 15a, 1 15b and 1 15c being visible in the figure). All the sensors and all the actuators of each sector 1 15a, l 15b, 1 15c are connected to a communication channel (bus) 205a,205b,205c. Each bus 205a, 205b, 205c refers to an inspection hatch 210a,210b,210c, which is connected to an electricity main (schematically shown with a plug in the figure) for supplying the corresponding sensors and actuators. All the inspection hatches 210a,210b,210c concentrate into a control unit 215 that controls the operation of the entire alarm system 200.

A detail of this alarm system according to an embodiment of the invention is shown in the FIG.3.

For this purpose, one or more piezoelectric plates are fastened to each panel 120 of the fence 1 15. When the panel 120 vibrates, the piezoelectric plate is deformed thereby varying the electric charge stored therein; therefore, by monitoring the voltage corresponding to the current supplied by the electric charge of the piezoelectric plate it is possible to detect the vibration of the panel 120. Conversely, when an electric field is applied to the piezoelectric plate it changes thickness and/or length; therefore, by providing a variable voltage to the piezoelectric plate it is possible to cause its vibration that is transmitted to the panel 120.

In this way, the plates act as mere piezoelectric transducers that are not capable of performing the functions of the sensor/actuator (by themselves), which functions are obtained only thanks to their interaction with the object which they are fastened to (i.e., each panel in the example at issue). As a consequence, it is possible to exploit the whole extent of this object for considerably improving both the detection and the issue of the vibrations (and then its operation as sensor and actuator, respectively).

This allows implementing the sensors and the actuators in a cost-effective way; in addition, this simplifies and speeds up the operations required for their installation. This solution is very versatile, with the same components that may be used in various applications, and therefore they may be manufactured on a large scale. All of the above has a beneficial effect on the total cost of the alarm system.

Furthermore, the sensors and the actuators so obtained are robust and hardly subject to malfunctions, with a resulting increase of reliability of the entire alarm system.

Moreover, in the proposed specific implementation, one or more components of the structure to the alarmed themselves are also used as sensors and actuators; in this way, the structure to be alarmed no longer has a purely passive function as in the prior art, but it is itself involved actively in its own protection. This creates a synergy between the alarm system and the structure to be alarmed itself. Indeed, the sensors and the actuators are no longer stand-alone added elements, but it is the entire component of the structure to be alarmed (which the piezoelectric plates are fastened to) that acts as sensor and actuator.

The solution described above integrates the sensors and the actuators into the structure to be alarmed; in this way, the sensors and the actuators are concealed in the structure to be alarmed so that they are not immediately detectable. As a consequence, the disconnection of the sensors and/or the actuators, and then of the alarm system, is more difficult. All of the above substantially increases the effectiveness of the alarm system.

Preferably, some piezoelectric plates (hereinafter denoted as sensor plates 305s) are dedicated to operate the panel 120 as sensor, whereas other piezoelectric plates (hereinafter denoted as actuator plates 305a) are dedicated to operate the panel 120 as actuator. Preferably, the sensor plates 305s are thinner (for example, with a thickness of 0.3-0.7 mm over an extent of 100-400 mm²) to increase their sensitivity; on the contrary, the actuator plates 305a are thicker (for example, with a thickness of 0.8-1.2 mm over an extent of 100-400 mm²) to increase their power. In this way, it is possible to optimize the sensor plates 305 s and the actuator plates 305 a independently for the corresponding functions, thereby considerably enhancing their effectiveness. Advantageously, each panel 120 has a redundant structure with a plurality of sensor plates 305s and/or actuator plates 305a to increase the reliability in the event of failures thereof (for example, 1- 2/m²); the sensor plates 305s and the actuator plates 305a are arranged on the panel 120 so as to optimize their performance - for example, at most significant areas of the panel 120 adapted to improve the sensitivity to specific mechanical/acoustical vibrations in desired frequency ranges (such as in greatest curvature areas for specific dynamic responses of major interest). Furthermore, the actuator plates 305a may be provided only on some of the panels 120 to reduce the cost (for example, one every 5-10 when they are exclusively dedicated to cause an acoustical vibration). The sensor plates 305s detect the vibrations in a distributed manner thereby allowing obtaining a high density of vibration detection; all of the above results in greater sensitivity. Likewise, the actuator plates 305a distribute the vibrations over a wide surface thereby creating quasi-planar sound waves that provide a high sound immersivity (substantially limiting any shadow cones); all of the above results in greater efficiency.

With reference now to the FIG.4, it shows a principle block diagram of some components of the alarm system according to an embodiment of the invention.

Particularly, each sensor plate and each actuator plate (generically denoted with the reference 305) has two terminals connected to the corresponding bus (generically denoted with the reference 205) via a driving system being known per se (not shown in the figure). More specifically, the plate 305 comprises two conductive plates 405 and 410 (for example, of metallic material), between which a layer of piezoelectric material (for example, double-biased quartz) is arranged; the plate 410 has an (upper) free surface that is directly accessible to define a terminal of the plate 305, whereas the plate 405 is provided with an extension toward the plate 410 that defines another terminal of the plate 305. The plate 305 is fastened to the panel 120 by gluing a (lower) free surface of the plate 405 directly thereon (or on a support plate, not shown in the figure, which in turn is fastened to the panel 120 by means of screws or clamps, so as to facilitate the installation when lower performance is acceptable). For this purpose, there is used a glue layer 420, which has characteristics so as not to interfere substantially with the interaction between the panel 120 and the plate 305 ; for example, the glue layer 420 is made of a homogeneous epoxy glue and with a bandwidth complying with the frequencies of the signals to be treated (for example, 0-30 kHz). Preferably, the glue layer 420 is electrically insulating, so as to avoid any risks of over- voltages (for example, in case of lightning or stray currents across the panel 120 when of electrically conductive material); moreover, the g lue l ayer 420 may b e non-hygroscopic, and not subject to chromatic reactions/deteriorations in the presence of UV rays (for example, for installation in open environments). A resistor 425 and an electronic switch 430 (for example, implemented with a MOS transistor) are connected in series, in parallel to the plate 305; normally, the switch 430 is closed so as to discharge the plate 305 (which is comparable to a capacitor that would tend to accumulate electric charge between its terminals due to the unavoidable vibrations induced thereon); this maintains the voltage across the plate 305 at substantially zero value in normal conditions, avoiding its saturation.

The bus 205 is connected to an interface 435. The interface 435 transmits analog signals received from the (sensor) plates 305 on the bus 205 to an analog-to-digital (ADC) converter 440; the converter 440 transmits corresponding digital signals to an amplifier 445, which amplifies and provides them to a driving unit 450. Vice- versa, the driving unit 450 provides digital signals to a digital-to-analog (DAC) converter 455; the converter 455 transmits corresponding analog signals to an amplifier 460, which amplifies and provides them to the interface 435 for their sending to the (actuator) plates 305 or to the switches 430 on the bus 205. Preferably, the driving unit 450 has two distinct sections for the sensor plates and for the actuator plates (so as to simplify its construction).

The driving unit 450 interfaces the control unit 215 (which is typically provided with a backup battery, not shown in the figure, to ensure its operation even in the absence of power supply). The control unit 215 comprises various modules that are connected in parallel to one or more buses 455 - with a structure that is suitably scaled according to the type of the control unit 215, in turn depending on the complexity of the corresponding alarm system (for example, from a PLC for small private installations to a server computer for large industrial installations). In detail, one or more processors 460 control the operation of the control unit 215, a RAM 465 is used as a working memory by the processors 460, a ROM 470 contains base code for a bootstrap of the control unit 215, and a mass memory 475 (from a simple flash memory to one or more hard-disks and readers/burners of optical discs) stores data to be preserved even in the absence of power supply. Furthermore, the control unit 215 comprises input/output (I/O) units 480; these input/output units may span from a small touch-screen to a monitor, keyboard and mouse. In addition, the input/output units 480 may also comprise a network card (for example, of Ethernet type) for connecting the control unit 215 to a router (not shown) that implements an access to the Internet.

The main software components that may be used to implement the solution according to an embodiment of the invention are shown in the FIG.5. These software components are denoted as a whole with the reference 500. The information (programs and data) is typically stored in the mass memory and loaded (at least partially) into the working memory of the control unit when the programs are running. The programs are initially installed onto the mass memory, for example, from optical discs.

Particularly, a monitor 505 monitors the (induced) vibration that is detected by each sensor plate. The monitor 505 interfaces a detector 510; the detector 510 detects each alarm condition by comparing the induced vibrations with alarm thresholds, which are stored in a repository 515. The detector 510 also logs time series of the induced vibrations into a corresponding repository 520. A configurator 525 accesses the repository of the time series 520, and it changes the alarm thresholds in the repository 515 accordingly. The detector 510 interfaces a validator 530; the validator 530 validates (i.e., confirms) each alarm condition by comparing the corresponding induced vibration with validation rules, which are stored in a different repository 535. The repository of the validation rules 535 as well is controlled by the configurator 525, which changes the validation rules according to the time series extracted from the repository 520. The validator 530 interfaces a signaler 540, which activates the actuator plates to cause their vibration in response to each (detected and validated) alarm condition. At the same time, the signaler 540 may also record a sound corresponding to the induced vibration into a file 545. In addition or in alternative, the signaler 540 interfaces a Voice over IP (VoIP) module 550, which is used to establish a telephone conversation over the Internet. Finally, the monitor 505 interfaces a verifier 555 that is used to verify the correct operation of the alarm system.

An activity diagram describing the flow of activities relating to an implementation of the solution according to an embodiment of the invention is shown in the FIG.6A- FIG.6C; in this respect, each block in the diagram may represent a module, segment or portion of code, which comprises one or more executable instructions for implementing the specified logical function (or more).

Particularly, the diagram represents an exemplary process that may be used to manage the above-described alarm system with a method 600. The flow of activity begins at the black start circle 602 and then passes to block 604 wherein a signal representative of the induced vibration of each sensor plate (suitably conditioned and filtered with techniques being known per se) is sampled continuously (for example, every 5-20 ms). Each time a detection time-out expires (for example, every 0.5-2 s) - after an initial transient period equal to the duration of a first detection period (see below) - the activity flow passes from block 606 to block 608. In this phase, a vibration index Iv is calculated according to a previous series of samples of the induced signal in a corresponding detection period of predetermined duration. The duration of this detection period and the calculation manner of the vibration index Iv vary according to the setting of the alarm system for configuring the alarm thresholds (see below). Particularly, in a short-term (ST) or long-term (LT) mode, the detection period has a relatively limited duration (for example, 5-20 s) and the vibration index Iv may be set equal to the Root-Mean-Square (RMS) value of these samples; therefore, the vibration index Iv will always have a very low positive, or at most zero, value (corresponding to a background noise) if the sensor plate has not detected any induced vibration in the detection period and a higher value otherwise, with the value of the vibration index Iv increasing as the intensity of the induced vibration in the detection period increases. In a real-time (RT) mode, instead, the detection period has a longer duration (for example, 30-120 s) and the vibration index Iv may be set equal to the Peak-to-Average Ratio (PAR), or crest factor - i.e. , peak amplitude divided by root mean square value; therefore, the vibration index Iv will have a substantially zero value in the presence of a steady induced vibration and a positive value otherwise, with the value of the index vibration Iv increasing as the peak of the induced vibration in the detection period increases.

The flow of activity branches at block 610 according to the setting of the alarm system. If the alarm system is set to configure the alarm thresholds in real-time, the flow of activity passes from the block 610 to block 614, wherein the alarm threshold THa for the sensor plate in this detection period is calculated according to the same series of samples, but with a different method from that used to calculate the vibration index Iv. For example, the alarm threshold THa may be set equal to the root mean square value of such samples; in this way, the alarm threshold THa will correspond to a base value of the induced signal in the detection period, which therefore allows detecting any spikes in the induced signal (which instead contribute to define the vibration index Iv); as set out above, in this case the duration of the detection period is maintained relatively long, so as to sufficiently differentiate the statistical value (which defines the alarm threshold THa) from the punctual value (which defines the vibration index Iv). In this real-time configuration mode, the alarm thresholds self-adapt to the actual environmental conditions at every moment (for example, varying with a background noise).

The flow of activities merges at block 616 from the block 614 or directly from the block 610 (when the real-time configuration is not active). In any case, the vibration index Iv is compared with the corresponding alarm threshold THa; particularly, in the real-time configuration mode the alarm threshold THa has just been calculated as described above, whereas otherwise it is extracted from the corresponding repository for the sensor plate and for the specific temporal condition (see below). If the vibration index

Iv is lower than the alarm threshold THa (to indicate that no alarm condition is detected), the activity flow returns to the block 606 waiting for a next expiry of the detection timeout for each sensor plate.

Conversely, when the vibration index Iv is equal to or higher than the alarm threshold THa (to indicate a possible alarm condition), the flow of activity descends from the block 616 into block 618. In this phase, the induced signal (in the detection period) is converted from the time domain to the frequency domain in order to obtain a spectral representation thereof - for example, by applying the Fast Fourier Transform (FFT) to the corresponding series of samples. Continuing to block 620, a set of validation rules (corresponding to the sensor plate and/or the temporal condition) is extracted from the corresponding repository. For example, the validation rules may contain different spectral models each one indicative of a critical environmental conditions (for example, rain and hail) - either provided as a basic configuration of the alarm system or self-learned by itself over time (see below); for each spectral model, a tolerance threshold to identify a match therewith is specified. A test is performed at block 622 to determine whether each one of these validation rules is fulfilled. Particularly, in the specific case at issue each validation rule is fulfilled if the spectral representation of the induced signal matches the corresponding spectral model; for example, for this purpose it is possible to measure a difference between the envelopes of the spectral representation of the induced signal and of the spectral model - for example, equal to their Mean Square Error (MSE) - and to compare this difference with the corresponding threshold value.

If at least one of the validation rules is not fulfilled (indicating that the alarm condition is not validated), the activity flow returns to the block 606 waiting for the next expiry of the detection time-out for each sensor plate. Conversely, when all the validation rules are fulfilled (to indicate that the alarm condition is validated), the flow of activity descends from the block 622 into block 624. In this phase, the alarm condition is recognized. As a consequence, the actuator plates (or at least part of them, for example, one for each panel) are activated; this causes an (alarm) vibration of the corresponding panels (for example, to emit an alarm sound intended to attract the attention of nearby people and to make the burglars to flight). Continuing to block 626, at the same time a sound corresponding to the induced vibration of the sensor plate at issue (and of other sensor plates, for example, one for each predefined area of the structure to be alarmed) is recorded. This allows a user of the alarm system to hear the sounds being emitted after the detection of an alarm condition later on. For example, these recordings may be used to provide useful information to the police in order to identify the burglars (according to their conversations), or they may be used for learning operations of the validation rules intended to recognize the causes of false alarm conditions detected by mistake. With reference to block 628, a telephone conversation is also established using the VoIP technology (with one or more pre-set telephone numbers). For this purpose, the corresponding sensor plate is initially used as a microphone; this role then automatically switches to the sensor plate that detects the highest sound at the moment (even if the corresponding induced vibration is not indicative of further alarm conditions). At the same time, an actuator plate close to the sensor plate operating as microphone is used as a speaker. In this way, it is possible to try to understand what is actually happening; moreover, this also allows frightening the burglars (for example, informing them of the arrival of the police). This result is achieved in a very effective way, with the microphone and the speaker that automatically move with the burglars. The flow of activity then returns to the block 606 (waiting for the next expiry of the detection time-out for each sensor plate) as soon as the normal operating condition of the alarm system has been restored (for example, by inserting a corresponding re-activation code by the user).

In a completely independent way, if the alarm system is set for configuring the alarm thresholds in the long-term, the flow of activity passes from the block 630 to block 632 whenever a logging time-out expires (for example, every 10-60 min.). In this phase, the vibration indexes Iv being calculated during each measurement period after the earlier expiry of this logging time-out are added to the time series of the corresponding temporal condition, removing or compressing the values being logged from the longest time; for example, it is possible to have a time series for the daytime hours (such as from 7:00 to 20:00) and a time series for the night (from 20:00 to 7:00). The method then returns to the block 630 waiting for a next expiry of this logging time-out.

The flow of activity then passes from block 634 to block 636 when a configuration of the alarm system in the long-term mode is required (for example, via the manual insertion of a corresponding command by the user or automatically in a periodic way, for example, every 1-2 months). In response thereto, the different time series are extracted from the corresponding repository. Continuing to block 638, for each time series its cumulative distribution is calculated (which, for each value of the vibration index Iv in the time series, indicates the relative frequency of the values lower than or equal to it, up to reach 100% for its maximum value). A cumulative distribution being more extended in time is estimated at block 640 with extrapolation techniques - for example, to predict its extreme values over a longer logging period with the generalized Extreme Value Distribution (EVD); this allows increasing the reliability of the obtained results (especially when the time series are relatively short). The alarm thresholds THa of the various sensor plates are then set at the block 642 for the different temporal conditions according to the corresponding estimated cumulative distributions. For example, each alarm threshold THa may be set equal to a multiple (such as 1.5-3 times) of a corresponding percentile of the estimated cumulative distribution (such as the 98-99% percentile); in this way, the alarm threshold THa takes a value sufficiently higher than the values of the vibration index Iv that have been detected in the vast majority of the cases (i.e., in normal operating conditions). In this long-term configuration mode, the alarm thresholds may be set differently according to the environmental conditions (for example, increasing at day-time when the background noise is greater and decreasing at night when it is smaller). The method then returns to the block 634 waiting for a next request of configuration of the alarm system.

In a completely independent way, if the alarm system is set to configure the alarm thresholds in the short-term, the flow of activity passes from block 644 to block 646 whenever a configuration time-out expires (for example, every 30-90 min.); in this phase, a loop is executed for each sensor plate to be configured (starting from the first one). Passing to block 648, the sensor plate is disabled (so as not to contribute to the recognition of the alarm condition temporarily). With reference to block 650, the induced signal of the sensor plate is sampled as above for a pre-defined measurement period (for example, 20-60 s). A test is then performed at block 652 to determine whether an alarm condition has been detected during the measurement period (from the other sensor plates remained enabled, so as not to create any risk condition). If so, the configuration procedure is aborted (since the detected values are not representative of the normal operating condition), and the activity flow returns to the block 644 waiting for a next expiry of the configuration time-out. Conversely, the activity flow passes from the block 652 to block 654 wherein the alarm threshold THa for the sensor plate is set equal to a multiple (for example, 1.5-3 times) of a value calculated according to the series of samples thus obtained with the same method used to calculate the vibration index Iv (i.e., equal to their mean square value in the example at issue) - with this value of the alarm threshold THa that replaces the previous one in the corresponding repository. In this way, the alarm threshold THa corresponds exactly to the induced signal in the measurement period. In this short-term configuration, the alarm thresholds self-adapt automatically over time to the variation of the different environmental conditions (for example, the background noise). The sensor plate is then re-enabled at block 656. A test is performed at block 658 to verify whether all the sensor plates have been processed. If not, the activity flow returns to the block 646 to repeat the same operations on a next sensor plate. Conversely, the method returns to the block 644 waiting for a next expiry of the configuration time-out.

The flow of activity instead passes from block 660 to block 662 whenever a verification time-out expires (for example, every 1-2 hours); in this phase, a loop is executed for each sensor/actuator plate to be verified (starting from the first one). Passing to block 664, the plate is disabled (so as not to contribute to the recognition of the alarm condition temporarily in the case of sensor plate). With reference to block 666, the discharge resistor is decoupled from the plate by opening the corresponding switch. A test is performed at block 668 after a pre-defined verification period (for example, 10-60 s). If the voltage across the plate has not reached a saturation value (for example, 1-3V), indicating a non-correct operation thereof, an error condition is detected at block 670 (for example, a fault or a tampering); in this case, the plate in error is excluded and a corresponding warning is reported on the control unit. The flow of activity then continues to block 672; the same point is also reached directly from the block 668 if the voltage across the plate has reached the saturation value (to indicate a correct operation thereof). A test is then performed to verify whether all the plates have been processed. If not, the activity flow returns to the block 662 to repeat the same operations on a next plate.

Conversely, the flow of activity descends from the block 672 into block 674, wherein a further loop is performed for each actuator plate to be verified (starting from the first one). Passing to block 676, the actuator plate is driven to cause a verification vibration of the corresponding panel in a further verification period (for example, 5-20 s); the verification vibration has a pseudo-random pattern, but in any case with an intensity that does not cause the recognition of any alarm condition (i.e., with its vibration index Iv markedly lower than any of the corresponding alarm thresholds THa). The induced vibration during the same period in a set of two or more sensor plates (to be verified as well) associated with this actuator plate (for example, in the same panel) is measured at block 678. Assuming that no alarm condition has been detected in the verification period, each induced vibration is compared with the verification vibration at block 680 (for example, according to an analysis of their spectral profiles). If no induced vibration is equal to the verification vibration (to indicate that the verification vibration has not been issued by the actuator plate), an error condition of the actuator plate is detected at block

682 (for example, excluding the actuator plate in error and reporting a corresponding warning on the control unit). If instead some induced vibrations are equal to the verification vibration but other induced vibrations are different therefrom (indicating that the verification vibration has not been detected by the corresponding sensor plates), an error condition of such sensor plates is detected at block 684 (for example, excluding the sensor plates in error and reporting a corresponding warning on the control unit). The flow of activity merges again at block 686 from the block 682, from the block 684, or directly from the block 680 (when all the induced vibrations are equal to the verification vibration, indicating that the verification vibration has been correctly emitted and detected.) A test is then performed to verify whether all the actuator plates have been processed. If not, the flow of activity returns to the block 674 to repeat the same operations on a next actuator plate. Conversely, the method returns to the block 660 waiting for a next expiry of the verification time-out.

Various examples of application of the solution according to an embodiment of the invention are shown in the FIG.7A-FIG.7G.

Starting from the FIG.7 A, it shows the trend over time (from 0s to 60s) of the amplitude of the induced signal detected by a generic sensor plate (in arbitrary units, from -2 to +2) - denoted with the reference 700A. As may be seen, the induced signal 700A is substantially zero in normal conditions, whereas it exhibits a strong oscillation around the zero value between 12 s and 18 s (for example, caused by a burglar who is climbing over the fence).

As shown in the FIG.7B, the corresponding vibration indexes Iv being calculated in detection periods of 10 s (denoted with the reference 700B), are always substantially zero, except for the detection period from 10 s to 20 s wherein the vibration index Iv takes the value 0.28. Therefore, assuming that the corresponding alarm threshold is THa=0.2, the alarm condition is correctly recognized.

Passing to the FIG.7C, there is shown the spectral representation of the induced signal, i.e., the amplitude (in arbitrary units from 0 to 0.04) of its harmonic components

(from 10-1 Hz to 103 Hz) - denoted with the reference 700C. As may be seen, the harmonic components of the induced signal are concentrated around 600 Hz.

In the FIG.7D a spectral model 700D in rain condition is instead shown. In this case, the spectral model 700D exhibits harmonic components at higher frequencies, which allow clearly differentiating the spectral representation of the induced signal (700C in the

FIG.7C) from this spectral model 700D (and thus validating the alarm condition).

Likewise, in the FIG.7D a spectral model 700E in hail conditions is shown. In this case, the spectral model 700E exhibits harmonic components even more pronounced at higher frequencies, which allow differentiating even more clearly the spectral representation of the induced signal (700C in the FIG.7C) from this spectral model 700E (and thus validating the alarm condition).

With reference now to the FIG.7F, the time series (over 5 days) are shown of the vibration indexes Iv (in arbitrary units, from 0 to 0.14) of two different sensor plates - denoted with the references 700Fa and 700Fb. As may be noted, the vibration indexes Iv have values substantially uniform, with a slight peak around the time 13:30 of the third day, because of a storm. In this case, the corresponding alarm threshold is set to THa=0.06, so as to be substantially higher than the vibration indexes Iv that may be detected in normal conditions (regardless of the weather conditions).

In the FIG.7G two other time series (between two consecutive nights) are instead shown of the vibration indexes Iv (in arbitrary units, from 0 to 14- 10^"3) of two different sensor plates - denoted with the references 700Ga and 700Gb. As may be seen, the trend of the vibration indexes Iv is substantially different between the nighttime hours (start and end) and the daytime hours (middle). In this case, the corresponding alarm threshold is set to THa=6 10^~3 for the nighttime hours and to THa=8 10^~3 for the daytime hours, so as to take into account the varying intensity of the background noise in the two environmental conditions.

Naturally, in order to satisfy local and specific requirements, a person skilled in the art may apply many logical and/or physical modifications and alterations to the above- described solution. More specifically, although this solution has been described with a certain degree of particularity with reference to one or more embodiments thereof, it should be understood that various omissions, substitutions and changes in the form and details as well as other embodiments are possible. Particularly, different embodiments of the invention may even be practiced without the specific details (such as the numerical values) set forth in the preceding description to provide a more thorough understanding thereof; conversely, well-known features may have been omitted or simplified in order not to obscure the description with unnecessary particulars. Moreover, it is expressly intended that specific elements and/or method steps described in connection with any embodiment of the disclosed solution may be incorporated in any other embodiment as a matter of general design choice. In any case, ordinal or other qualifiers are merely used as labels to distinguish elements with the same name but do not by themselves connote any priority, precedence or order. Moreover, the terms include, comprise, have, contain and involve (and any forms thereof) should be intended with an open, non-exhaustive meaning (i.e. , not limited to the recited items), the terms based on, dependent on, according to, function of (and any forms thereof) should be intended as a non-exclusive relationship (i.e. , with possible further variables involved), and the term a/an should be intended as one or more items (unless expressly indicated otherwise).

For example, one embodiment of the invention provides an alarm system for alarming a structure. The alarm system comprising a set of (one or more) sensors each one for detecting an induced vibration. Processing means is provided for recognizing an alarm condition according to the induced vibration of at least one of the sensors. The alarm system further comprises a set of (one or more) actuators each one for causing an alarm vibration in response to the recognition of the alarm condition. In the solution according to an embodiment of the invention, the alarm system comprises a set of (one or more) objects. Each one of these objects is associated with at least one transducer for detecting the induced vibration of said object and for causing the alarm vibration of said object.

However, the alarm system may be used in any application; examples of alternative applications of the alarm system are in a pipeline (to prevent acts of vandalism), in a vehicle (to prevent its theft or damage), in a shower box (to report strokes), in structures exposed to the public (to prevent acts of vandalism) and the like. The sensors may be of any type (see below) and used to detect any induced vibration (for example, only mechanical one in very noisy environments or only acoustical one to detect presences close to it). The processing means may be implemented in any way and it may recognize the alarm condition based on any criteria (see below). Likewise, the actuators may be of any type (see below) and used to cause any alarm vibration (for example, only mechanical one to remove animals, only acoustical one to frighten burglars, or both of them). The objects that implement the sensors and the actuators may be of any type, shape, size, and in any position and number, and they may comprise transducers of any type and in any position and number in each one of them (see below).

In an embodiment of the invention, each object is a component of the structure to be alarmed that has an original function in the structure to be alarmed neither of sensor nor of actuator of the alarm system; the component further operates as sensor and actuator of the alarm system when said corresponding at least one transducer is applied to the component. However, any component of the structure to be alarmed may be used for implementing the sensors and the actuators (for example, a gate, a mesh, a door, a solar panel, a glass plate, a body of a vehicle, a mobile, a lamp, a picture, and so on); this component may have any structure (for example, solid to detect both mechanical and acoustical vibrations or grill-like to detect mechanical vibrations only but not acoustical vibrations) and it may be made of any material (for example, wood, marble, concrete, metal, glass). Moreover, it is possible to provide mechanical protection barriers to prevent false alarms (for example, caused by impacts of animals). In any case, an implementation wherein the objects that implement the sensors and the actuators are added to the structure to be alarmed (for example, panels already pre-assembled with the respective transducers) is not excluded.

In an embodiment of the invention, each object comprises an element with a substantially flat extension; said at least one transducer of the object comprises at least one sensor piezoelectric plate being fastened to said element for detecting the induced vibration of the object and at least one actuator piezoelectric plate being fastened to said element for causing the alarm vibration of the object.

However, the object that implements the sensors and the actuators may also have a non-flat shape, such as in the case of tubes (for example, adding an interface plate for the piezoelectric plates). Moreover, the sensor plates and the actuator plates may be distributed in any way; in addition, nothing prevents having plates being used interchangeably both as sensors and as actuators. In any case, the possibility of implementing the transducers in another way is not excluded (for example, with magneto- restrictive plates, with accelerometers/strain gauges).

In an embodiment of the invention, the processing means comprises monitoring means for monitoring the induced vibration being detected by each sensor by repeatedly calculating a vibration index indicative of the induced vibration in a corresponding detection period; moreover, it comprises detection means for detecting the alarm condition according to a comparison between each vibration index and an alarm threshold.

However, the detection period may have any duration, and the alarm threshold may have any value and it may be defined in any way (see below). Moreover, the vibration index may be compared with the alarm threshold in another way (for example, detecting the alarm condition with a vote majority policy). In any case, the alarm condition may be recognized in any other way (for example, using fuzzy logic techniques).

In an embodiment of the invention, the processing means comprises configuring means for setting at least one alarm threshold for each sensor.

However, the alarm thresholds may be defined in any number (for example, individually for each sensor, for group s o f sensors in similar conditions or indiscriminately for all the sensors) and they may be configured in any way (see below).

In an embodiment of the invention, the configuration means comprises means for logging a plurality of log series of the alarm indexes of each sensor (with the alarm indexes of each log series that correspond to a different temporal condition). Means is provided for setting a plurality of alarm thresholds for each sensor each for one of the temporal conditions according to the corresponding log series of alarm indexes. In this case, the detection means comprises means for detecting the alarm condition according to a comparison between each vibration index of each sensor and the alarm threshold of the sensor for the temporal condition corresponding to the detection period of the vibration index.

However, the logging period may have any duration, the time series may be defined for any other or alternative environmental conditions (for example, according to the working and non-working days), and the alarm thresholds may be calculated in any other way from the corresponding time series.

In an embodiment of the invention, the configuration means comprises means for repeatedly recording the induced vibration being detected by each sensor to be configured in a measurement period. Means is provided for setting the alarm threshold of each sensor to be configured according to the recorded induced vibration if no alarm condition is detected by the other sensors.

However, the measurement period may have any duration, and the alarm threshold may be calculated in any other way from the corresponding measured vibration (even without disabling the sensor plates to be verified).

In an embodiment of the invention, the configuration means comprises means for setting the alarm threshold of each sensor for each detection period according to a first calculation method based on the corresponding induced vibration. The corresponding vibration index is calculated according to a second calculation method, different from the first calculation method, based on the corresponding induced vibration. However, the alarm threshold and the vibration index may be calculated according to any other calculation method (for example, using the mean square value being applied to the original induced vibration for the vibration index and to a version thereof with its peaks of short duration being filtered out for the alarm threshold).

In any case, the alarm thresholds may be configured in different or alternatives ways (for example, with pre-set safety values), or with any combination thereof.

In an embodiment of the invention, the processing means comprises means for storing a set of (one or more) validation rules of the alarm condition. Validation means is provided for validating the alarm condition according to a comparison between the corresponding induced vibration and the validation rules.

However, the validation rules may be of any type (see below) and they may be used in any way to validate the alarm condition (for example, according to statistical considerations).

In an embodiment of the invention, the validation rules comprise a set of (one or more) spectral models each one indicative of a critical environmental condition. The validation means comprises means for calculating a spectral representation of the induced vibration corresponding to the alarm condition and for comparing the spectral representation with the spectral models.

However, any technique (both analytical one and numerical one) may be used to compare the spectral representation with the spectral models, or more generally to perform a verification in the frequency domain (for example, based on the energy spectra). In any case, the validation rules may be of any other type (for example, requiring the verification of other adjacent sensor plates, a certain persistence in time of the alarm condition, and the like).

In an embodiment of the invention, each piezoelectric plate is coupled with a discharge resistor for preventing a saturation thereof. The alarm system further comprises means for disabling each one of the piezoelectric plates to be verified in turn in a corresponding verification period. Means is provided for decoupling the discharge resistor from the piezoelectric plate to be verified in the verification period. Means is provided for determining a correct operation of the piezoelectric plate to be verified according to a saturation thereof being measured in the verification period.

However, the verification may be performed at any time (for example, upon request or after a maximum time without the recognition of any alarm condition), and the verification period may have any duration.

In an embodiment of the invention, the alarm system further comprises means for driving one of the actuators to be verified in turn to cause a verification vibration to occur in a corresponding further verification period. Means is provided for determining a correct operation of the actuator to be verified and of a plurality of sensors to be verified associated with the actuator to be verified according to a comparison between the verification vibration and the induced vibration in each one of the sensors to be verified in the verification period.

However, as above the verification may be performed at any time (for example, upon request or after a maximum time without the recognition of any alarm condition), and the verification vibration may be of any type.

In any case, the verification of the alarm system may be performed by using different or alternatives techniques (either alone or in combination), or it may also be omitted entirely.

In an embodiment of the invention, the alarm system further comprises means for recording a sound corresponding to the induced vibration being detected by at least one of the sensors.

However, the sound may be recorded in another way (for example, always by all the sensor plates).

In an embodiment of the invention, the alarm system further comprises means for establishing a telephone conversation using at least one of the sensors as a microphone and at least one of the actuators as a speaker in response to the recognition of the alarm condition.

However, the telephone conversation may be established in another way (for example, on a standard telephone line) and using the plates in another way (for example, to provide a stereo effect).

In an embodiment of the invention, the means for establishing a telephone conversation comprises means for changing said at least one sensor used as a microphone according to a comparison of the induced vibrations of the sensors and for changing said at least one actuator used as a speaker according to the changing of said at least one sensor used as a microphone.

However, the sensor(s) used as microphone and the actuator(s) used as speaker may be changed in any way (for example, with hysteresis so as to enable the switching to another sensor only when the intensity of the detected sound exceeds the one of the current sensor by a pre-defined threshold); moreover, nothing prevents changing the sensor only, the actuator only, or none of them (i.e., using the plates in a stationary manner as microphone and speaker).

In any case, different or alternatives actions may be performed in response to the alarm condition (for example, the activation of one or more web-cams); on the contrary, the alarm condition may only cause the activation of the actuators without any additional action.

Another embodiment of the invention provides an alarmed structure comprising this alarm system.

It should be noted that the above-described use of the plates to implement a telephone conversation (in the broadest meaning of the term, for example, comprising a conference call) lends itself to be applied also independently of the alarm system.

For example, another aspect of the invention provides a telephone apparatus.

The telephone apparatus may be used in various structures. For example, this structure may be an office. The office comprises a number of components, for example, architectural elements (such as windows and doors) and furniture elements (such as desks and cabinets). As above, a same object (preferably a component of the office) is used both as sensor (to implement a microphone) and as actuator (to implement a loudspeaker) by means of one or more piezoelectric plates that are fastened thereto (with the sensors and the actuators that are adequately connected one to another via specifically designed electrical circuitry able to amplify the detection/emission capability).

Moreover, the telephone apparatus further comprises a controller that is coupled with the control unit; preferably, the controller is implemented with a portable device that communicates with the control unit via a wire-less connection (for example, of the bluetooth type). Schematically, the controller comprises a rechargeable-battery that supplies its components (adapted to be coupled in a removable manner with a corresponding battery charger connected to the electricity main). Particularly, these components comprise an integrated circuit that implements the functions of the controller and a non- volatile memory (for example, a flash memory) that stores data to be preserved even in the absence of power supply. Furthermore, the controller comprises input/output units; these input/output units may comprise a keypad for dialing a telephone number to be called and for entering other commands to the controller (for example, for managing a phone book) and a display for showing the telephone number of an (inbound or outbound) call or other service information (for example, the content of the phone book).

More specifically, an aspect of the invention provides a telephone apparatus for performing a telephone conversation, the telephone apparatus comprising a set of (one or more) sensors, or microphones, each one for detecting an input vibration corresponding to an outbound sound of the telephone conversation and a set of (one or more) actuators, or speakers, each one for causing an output vibration corresponding to an inbound sound of the telephone conversation, characterized by a set of (one or more) objects each one associated with at least one transducer for detecting the input vibration of said object and for causing the output vibration of said object.

However, the telephone apparatus may be used in any application (for example, at home or in a vehicle).

In an embodiment of the invention, the telephone apparatus further comprises interface means for starting the telephone conversation and for accepting the telephone conversation.

However, the interface means may be used to provide any other commands (for example, for managing a conference call), and it may be implemented in any way (see below).

In an embodiment of the invention, the telephone apparatus comprises control means for controlling the telephone conversation; the interface means comprises a mobile device being coupled with the control means via a wire-less connection.

However, the control means may be implemented in any way (for example, by embedding a transceiver that establishes the telephone conversation directly); moreover, the interface means may be of any other type (for example, a fixed console), and it may be coupled with the control means in any way (for example, via a wired connection).

In an embodiment of the invention, the telephone apparatus comprises telephone means for establishing the telephone conversation.

However, the telephone means may be implemented in any way (see above). In any case, nothing prevents using a pre-existing device (for example, a smart phone) to implement the functions of the telephone means (so that the proposed telephone apparatus simply operates as a viva-voce system thereof).

All the other (structural and functional) features described above with respect to the alarm system apply mutatis mutandis to the telephone apparatus. Another embodiment of the invention provides a structure comprising such telephone apparatus.

Generally, similar considerations apply if the alarm system, the alarmed structure, the telephone apparatus and the corresponding structure each has a different structure or comprises equivalent components (for example, of different materials), or it has other operative characteristics. In any case, every component thereof may be separated into more elements, or two or more components may be combined together into a single element; moreover, each component may be replicated to support the execution of the corresponding operations in parallel. Moreover, unless specified otherwise, any interaction between different components generally does not need to be continuous, and it may be either direct or indirect through one or more intermediaries.

Another embodiment of the invention proposes a method for alerting a structure; the method comprises the following steps. An induced vibration is detected by a set of sensors. An alarm condition is recognized according to the induced vibration of at least one of the sensors. An alarm vibration is caused in response to the recognition of the alarm condition by a set of actuators. In the solution according to an embodiment of the invention, said detecting an induced vibration and said causing an alarm vibration comprise, for each one of a set of objects, detecting the induced vibration of said object and causing the alarm vibration of said object by at least one transducer associated with the object.

Another aspect of the solution according to an embodiment of the invention provides a method for performing a telephone conversation, the method comprising: detecting an input vibration corresponding to an outbound sound of the telephone conversation, causing an output vibration corresponding to an inbound sound of the telephone conversation, characterized in that said detecting an input vibration and said causing an output vibration comprises, for each one of a set of objects, detecting the input vibration of said object and causing the output vibration of said object by at least one transducer associated with the object.

However, similar considerations apply if the same solution is implemented with an equivalent method (by using similar steps with the same functions of more steps or portions thereof, removing some steps being non-essential, or adding further optional steps); moreover, the steps may be performed in a different order, concurrently or in an interleaved way (at least in part). Another embodiment of the invention proposes a computer program comprising code means for causing a data processing system to perform the steps of each one of the above methods when the computer program is executed on the data processing system.

Another embodiment of the invention proposes a computer program product comprising a non-transitory computer readable medium embodying a computer program, the computer program comprising code means directly loadable into a working memory of a data processing system thereby configuring the data processing system to perform each one of the same methods.

However, the solution described above may be implemented locally or remotely (at least in part). In any case, similar considerations apply if the program (which may be used to implement each embodiment of the invention) is structured in a different way, or if additional modules or functions are provided; likewise, the memory structures may be of other types, or may be replaced with equivalent entities (not necessarily consisting of physical storage media). The program may take any form suitable to be used by any data processing system or in connection therewith (for example, within a virtual machine), thereby configuring the system to perform the desired operations; particularly, the program may be in the form of external or resident software, firmware, or micro-code (either in object code or in source code - for example, to be compiled or interpreted). Moreover, it is possible to provide the program on any computer-usable medium (and particularly as an article of manufacture on a non-transitory medium); the medium may be any element suitable to contain, store, communicate, propagate, or transfer the program. For example, the medium may be of the electronic, magnetic, optical, electromagnetic, infrared, or semiconductor type; examples of such medium are fixed disks (where the program may be pre-loaded), removable disks, tapes, cards, wires, fibers, wireless connections, networks, broadcast waves, and the like. In any case, the solution according to an embodiment of the present invention lends itself to be implemented even with a hardware structure (for example, integrated in a chip of semiconductor material), or with a combination of software and hardware suitably programmed or otherwise configured.

Claims

1 . An alarm system (200) for alarming a structure (100), the alarm system comprising a set of sensors (305 s) each one for detecting an induced vibration, processing means (215) for recognizing an alarm condition according to the induced vibration of at least one of the sensors, and a set of actuators (305a) each one for causing an alarm vibration in response to the recognition of the alarm condition,

characterized by

a set of objects (120) each one associated with at least one transducer (305s, 305th) for detecting the induced vibration of said object and for causing the alarm vibration of said object.

2. The alarm system (200) according to claim 1 , wherein each object (120) is a component of the structure (100) to be alarmed having an original function in the structure to be alarmed neither of sensor nor of actuator of the alarm system, the component further operating as sensor and actuator of the alarm system when said corresponding at least one transducer (305s, 305th) is applied to the component.

3. The alarm system (200) according to claim 1 or 2, wherein each object (120) comprises an element with a substantially flat extension, said at least one transducer (305s, 305th) of the object comprising at least one sensor piezoelectric plate (305s) being fastened to said element for detecting the induced vibration of the object and at least one actuator piezoelectric plate (305a) being fastened to said element for causing the alarm vibration of the object.

4. The alarm system (200) according to any one of claims 1 to 3, wherein the processing means (215) comprises monitoring means (505) for monitoring the induced vibration being detected by each sensor (305 s) by repeatedly calculating a vibration index indicative of the induced vibration in a corresponding detection period, and detection means (510) for detecting the alarm condition according to a comparison between each vibration index and an alarm threshold.

5. The alarm system (200) according to claim 4, wherein the processing means (215) comprises configuring means (505-525) for setting at least one alarm threshold for each sensor (305 s).

6. The alarm system (200) according to claim 5, wherein the configuration means (505-525) comprises: means (510,520) for logging a plurality of log series of the alarm indexes of each sensor, the alarm indexes of each log series corresponding to a different temporal condition, and means (525) for setting a plurality of alarm thresholds for each sensor each for one of the temporal conditions according to the corresponding log series of alarm indexes, the detection means (510) comprising means (510) for detecting the alarm condition according to a comparison between each vibration index of each sensor and the alarm threshold of the sensor for the temporal condition corresponding to the detection period of the vibration index.

7. The alarm system (200) according to claim 5 or 6, wherein the configuration means (505-525) comprises:

means (525) for repeatedly recording the induced vibration being detected by each sensor to be configured in a measurement period, and means (525) for setting the alarm threshold of each sensor to be configured according to the recorded induced vibration if no alarm condition is detected by the other sensors.

8. The alarm system (200) according to any claim from 5 to 7, wherein the configuration means (505-525) comprises:

means (525) for setting the alarm threshold of each sensor for each detection period according to a first calculation method based on the corresponding induced vibration, the corresponding vibration index being calculated according to a second calculation method, different from the first calculation method, based on the corresponding induced vibration.

9. The alarm system (200) according to any claim from 4 to 8, wherein the processing means (215) comprises means (535) for storing a set of validation rules of the alarm condition, and validation means (530) for validating the alarm condition according to a comparison between the corresponding induced vibration and the validation rules.

10. The alarm system (200) according to claim 9, wherein the validation rules comprise a set of spectral models each one indicative of a critical environmental condition, and wherein the validation means (530) comprises means (530) for calculating a spectral representation of the induced vibration corresponding to the alarm condition and for comparing the spectral representation with the spectral models.

1 1 . The alarm system (200) according to any one of claims 1 to 10 when dependent directly or indirectly on claim 3, wherein each piezoelectric plate (405-415) is coupled with a discharge resistor (425) for preventing a saturation thereof, the alarm system further comprising means (555) for disabling each one of the piezoelectric plates to be verified in turn in a corresponding verification period, means (430,555) for decoupling the discharge resistor from the piezoelectric plate to be verified in the verification period, and means (555) for determining a correct operation of the piezoelectric plate to be verified according to a saturation thereof being measured in the verification period.

12. The alarm system (200) according to any one of claims 1 to 1 1 , further comprising means (555) for driving one of the actuators (305a) to be verified in turn to cause a verification vibration to occur in a corresponding further verification period, and means (555) for determining a correct operation of the actuator to be verified and of a plurality of sensors to be verified associated with the actuator to be verified according to a comparison between the verification vibration and the induced vibration in each one of the sensors to be verified in the verification period.

13. The alarm system (200) according to any one of claims 1 to 12, further comprising means (540-545) for recording a sound corresponding to the induced vibration being detected by at least one of the sensors (305s) in response to the recognition of the alarm condition.

14. The alarm system (200) according to any one of claims 1 to 13, further comprising means (540,550) for establishing a telephone conversation using at least one of the sensors (305 s) as a microphone and at least one of the actuators (305 a) as a speaker in response to the recognition of the alarm condition.

15. The alarm system (200) according to claim 14, wherein the means for establishing a telephone conversation (540,550) comprises means (550) for changing said at least one sensor used as a microphone (305 s) according to a comparison of the induced vibrations of the sensors and for changing said at least one actuator used as a speaker

(305a) according to the changing of said at least one sensor used as a microphone.

16. A method (600) for alarming a structure comprising:

detecting (604-608) an induced vibration by a set of sensors,

recognizing (616-622) an alarm condition according to the induced vibration of at least one of the sensors, and

causing (624) an alarm vibration in response to the recognition of the alarm condition by a set of actuators,

characterized in that said detecting (604-608) an induced vibration and said causing (624) an alarm vibration comprise, for each one of a set of objects, detecting the induced vibration of said object and causing the alarm vibration of said object by at least one transducer associated with the object.

17. A computer program (500) comprising code means for causing a data processing system (215) to perform the steps of the method (600) according to claim 16 when the computer program is executed on the data processing system.

18. A computer program product comprising a non-transitory computer readable medium embodying a computer program, the computer program comprising code means directly loadable into a working memory of a data processing system thereby configuring the data processing system to perform the method according to claim 16.