DYNAMIC COLLISION DETECTION SYSTEM AND ANTI-CRASH PROTECTION BARRIER BELONGING TO THE SAID SYSTEM

Description

PATENT APPLICATION FOR INDUSTRIAL INVENTION TITLE: “DYNAMIC DETECTION SYSTEM OF POSSIBLE COLLISIONS AND “SHOCK PROTECTION BARRIER BELONGING TO THE SAID SYSTEM.” ******************** FIELD OF INVENTION The present invention relates to the field of crash protection systems. used in industrial fields. In particular, the present invention relates to the field of crash protection systems featuring active safety functions and reducing the risk of possible collisions. STATE OF THE ART The diffusion and importance of anti-shock protection systems in the field is well known. industrial. These systems are designed to protect infrastructure, vehicles and operators from possible collisions during normal activity. Crash protection systems are used, for example, to protect certain areas, such as pedestrian areas, or walls (and any structures associated with these walls), or even access points. The systems shockproof protection can also be used for the protection of certain machines, whether isolated or arranged in groups or rows. These protection systems can be made in various shapes and sizes: barriers of different lengths and heights, bollards, guardrails, gates, aligners, pedestrian parapets, height limiters, etc. The function of these protection systems means that they are often destroyed or severely damaged when called upon to intervene to avoid collisions. This in turn leads to huge recovery times and costs with heavy inconveniences in terms of suspension of operations pending completion of the restoration. Being able to have a collision avoidance system that has integrated the possibility of determining the motion and position of objects in movement closer and, in general, operating in a certain area of ​​interest, in in order to raise an alarm before a collision occurs, it would allow avoid the drawbacks described, and others that affect state-of-the-art systems. A crash protection system equipped with this predictive functionality collisions could also guarantee the possibility of collecting data on movements that occur in the immediate circumstances. This data could then be advantageously processed and analyzed in order to draw useful indications from them on traffic management in the monitored area and on their positioning crash protection systems and also of the operators present in the area. SUMMARY DESCRIPTION OF THE INVENTION The shock protection system according to this description allows the dynamic detection of possible collisions between the fixed barriers of the system shock protection and moving objects within an area of ​​interest predetermined. Furthermore, the aforementioned protection system allows to collect the data relating to the movements of vehicles and operators that occur under the circumstances of barriers of the protection system in order to provide a safety mapping of the area of ​​interest. The above mentioned shock protection system is based on a UWB technology sensor (Ultra Wide Band) designed to detect the position of a TAG or other sensor in UWB technology, within its area of ​​action by exploiting the technique of the angle of arrival (AoA) in conjunction with the distance measurement. This sensor in UWB technology can be advantageously connected to the Internet via a wired or wireless connection. This sensor in UWB technology, from now on simply referred to as sensor, is designed in such a way that it can operate correctly even in comparisons of TAGs, and other sensors that are at the same or similar height at the height of the sensor itself. This is achieved by using a plurality of antennas for UWB signals such that the limitation of the detection angle with respect to The z-axis is exceeded. The interaction between the sensor and other sensors in the area of interest and between sensor and TAG present in the area of ​​interest allows you to create an interaction between barrier and vehicles circulating in the area of ​​interest which can be used to create warning signals in situations where an imminent emergency is expected impact, but also to act on the vehicle controls in order to try to avoid the impact or make it less dangerous by reducing the speeds of the vehicles involved. This allows the use of lighter and less expensive barriers since they are called upon to sustain impacts at lower speeds and energy. We may also allow or prevent the opening of a gate or barrier based on the activity and traffic of vehicles detected in the circumstances of the said gate and of the said barrier. Furthermore, the data relating to all interactions recorded between the barrier and the circulating vehicle in the area of ​​interest, they can be post-processed in order to obtain statistical considerations on employment and traffic within the area interest, from which to extract corrections on the rules in force within the the aforementioned area of ​​interest (directions of travel, maximum speeds permitted for vehicles, positioning of barriers, etc.). Furthermore, the barrier according to the present description can advantageously also include means of geolocation so that the location geographical location of the said barrier can be precisely identified. By doing so, the positions of other operators and vehicles operating in the area of ​​interest can advantageously be referred to the position of the barrier in order to obtain detailed and georeferenced information on the routes taken by each person. This allows you to obtain valuable information on the characteristic logistics flows of the various areas of interest, information that can be useful not only for management of safety but also for the organization and optimization of the activities that are carried out by vehicles and operators within the areas of interest. Also This information can be shared, saved on remote cloud servers and made available for post-processing and analysis. Preferably, the sensors placed on the barriers are fixed, arranged with a certain default orientation based on which the angle of arrival can be calculated of a TAG or another sensor approaching, and geolocalized. When a mobile object, equipped with a TAG or a sensor, enters the area surrounding the barrier, the fixed sensor on board the barrier calculates at every moment the distance and angle at which it sees the moving object approaching and determines its position exactly. The barrier is therefore able to calculate the position of a mobile object equipped with of TAG or sensor that is circulating in the vicinity of the barrier itself, and of send it to the same mobile object; this way the mobile object is knowledge of the barrier with which an interaction has been established and knows its own relative position, one's distance and direction of travel with respect to that barrier. Furthermore, the moving object is also able to know its absolute position if it is provided with a map showing the positions of the barriers fixed. In case the movable object is a vehicle, for example a forklift, equipped with a screen (a tablet) for viewing georeferenced maps, advantageously the map of the activity area with the exact positions of the fixed barriers installed in the area may be displayed on board the vehicle, together with the exact location of the vehicle itself. Depending on the absolute position of the moving object and security protocols and foreseen, the intervention method can be easily decided and varied. for example, the speed and / or direction of the forklift can be changed, you can activate acoustic and / or optical warning devices etc. By means of the system according to this description the information obtained on work areas and on movable objects within those work areas can be refer to an absolute position and this allows for universal and uniform management of the data collected, the exchange of information with other applications and with other managers etc. According to the system described, geolocation can be used both to receive info from the mobile object within an area of ​​interest, either to modify the operating profile of moving objects based on their position. Collecting data on interactions between mobile vehicles and installed fixed barriers within a certain work area, moreover, through appropriate post-processing we can establish that in a given area there is a risk level higher than other comparable areas. In response to this determination, it can therefore be decided to mark the highest risk area automatically and, consequently, the maps shared with all mobile objects present in the area, and the related criteria security, can be adjusted automatically. The mobile object, in in essence, becomes aware of its position at the moment it interacts with the barrier and set your own operating profile regarding the maps georeference receipts, for example from a repository located on a remote cloud. The system according to this description, finally, is configured to be easily integrated into pre-existing barriers also by virtue of the fact that often these barriers are already equipped with wiring (for electricity or communication such as Ethernet cables). In this way the barriers equipped of sensors can help create networks (meshes) that can communicate with each other to cover areas of any size. BRIEF DESCRIPTION OF THE FIGURES Further features and advantages of the invention will become apparent from reading of the following detailed description, provided by way of example and not limitative, with the aid of the figures illustrated in the attached tables, in which: Fig. 1 illustrates a preferred embodiment of a crash barrier. equipped with dynamic detection of possible collisions in which a sensor is associated to the barrier and a TAG is associated with each of the moving objects in the area in where the barrier is placed, in particular to a forklift and to an operator who moves on foot; Fig. 2 illustrates a functional block diagram of the sensor hardware structure. and of the TAG of the system according to the present invention; Fig. 3 illustrates a schematic of the antenna arrangement in one embodiment. preferred sensor according to the present invention, and Fig. 4 illustrates a preferred embodiment of the antenna trio A1, A2, A3 by means of mono-conical antennas mounted on a circular ground plane. Fig. 5 illustrates a preferred embodiment of the antenna trio A1, A2, A3 by means of biconical antennas interspersed with non-conductive and radio-transparent materials, and Fig. 6 illustrates a preferred embodiment of the antenna trio A1, A2, A3 by means of mono-conical antennas mounted on a circular ground plane. The following description of exemplary embodiments refers to the attached drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description is not limited the invention. The scope of the invention is defined by the appended claims. DETAILED DESCRIPTION OF THE INVENTION The attached Fig. 1 illustrates the case in which a first TAG, 10, and a first transceiver, or sensor, 11, are associated with moving objects while a second transceiver, or sensor, 12 is associated with a fixed type barrier 15 or movable. Said TAG 10 and said sensors 11, 12 can, for example, operate in the frequency range between 2 GHz and 10 GHz. Considering, for example, an industrial area, said first transceiver or sensor 11 can be associated with a forklift 14 operating in the area and said first TAG 10 can be associated with an operator 13 who moves on foot or with other types of vehicles. With reference to the attached Figs. 2 and 3, in a preferred embodiment of the invention said first and second sensors 11, 12 each comprise at least three transceivers 20, 21, 22, 40, 41, 42 each associated with an antenna 23, 24, 25, 43, 44, 45. Said transceivers 20, 21, 22, 40, 41, 42 are connected to a control unit control 26, 46, configured to appropriately drive said transceivers 20, 21, 22, 40, 41, 42 and to manage at least one possible external interface 27, 47 which It can be a connection interface to external systems such as, for example, the machine on which said sensor 11 is installed, or a user interface for the display and configuration of the operating parameters of said sensors 11, 12, or even an interface for connecting to a local network or the Internet. The control unit 26, 46 may advantageously comprise a microcontroller and an associated memory unit designed to hold program instructions and data. In particular, said control unit 26, 46 are designed to regulate the sequences of transmission and reception and to process the signals transmitted and received by said TAG 10 or from another sensor in an appropriate manner to calculate its distance and speed of approach or departure. Said transceivers 20, 21, 22, 40, 41, 42, moreover, are preferably coherent, that is, they are connected to the same source of clock 28, 48. In a preferred embodiment of the invention, said transceivers 20, 21, 22, 40, 41, 42 are configured so that one is the main transceiver, capable of determine the distance from a TAG or another sensor, while the other two transceivers are capable of measuring the relative phase with respect to said transceiver principal. Said TAG 10 comprises at least one transceiver 29, an antenna 30 and a controller 31 configured to appropriately drive said transceiver 29 in way to manage the transmission and reception sequences, in particular towards the aforementioned sensors 11, 12. Preferably said TAG 10 further comprises a battery power supply so that it can be worn even by a non-operator associated with a vehicle. During operation of the system according to the invention, said second sensor 12 performs a transceiver exchange with said TAG 10 and / or with said first sensor 11 in order to determine their distance using known techniques, e.g. example based on Ultra Wide Band signals. Then, using the information connected to the signals received from TAG 10 and / or from the first sensor 11, the second sensor 12 operates in such a way as to measure the electrical phase of said signals received from the TAG and from the first sensor, and calculate the difference between the measured phases and, based on of this difference, the geometric angle of arrival of the signal transmitted by the TAG 10 and / or from the first sensor 11 and therefore the direction and geometric angle of approach of the TAG 10 and / or the first sensor 11 to the second sensor 12. Among the known techniques that allow to establish the time of flight of a signal electromagnetic and therefore the distance between a transmitter and a receiver are the RTT (Round Trip Time) techniques - based on a double transmission, first in one direction and then the other - or TWR (Two Way Ranging) which uses a increased number of transmissions between the two transceivers to allow for a greater immunity to some typical drifts of the electronics used such as, for example for example, the deviation of the frequency references of the two transceivers. In the present invention said second sensor 12 uses one of the radio exchanges in reception to also determine the geometric angle of arrival of the signal transmitted by the TAG, thanks to the use of a plurality of antennas 43, 44, 45. In a preferred embodiment, illustrated in the accompanying Fig. 3, the second sensor 12 It comprises a system of three antennas A1, A2 and A3 arranged at the vertices of a triangle approximately equilateral with side l. Let's consider this set of three antennas arranged in a Cartesian reference system with an x-axis and a y-axis. Considering the object on which the TAG 10 is placed (or the object on which it is the first sensor 11) is placed, it moves in a direction that is inclined of an arrival angle α with respect to the x-axis and has a distance d from the three antennas receivers, A1, A2 and A3, much greater than l. In this way the directions of arrival of the transmitter with respect to each of the three receiver antennas can be considered approximately parallel between them. The path difference of the signals transmitted by the transmitter, moreover, corresponds further to an electrical phase difference between the signals received by the three antennas receivers A1, A2 and A3. The electrical angle or electrical phase, θ, of the signals electromagnetic waves received by the three antennas can be expressed by the equation: θ = Δ 2π / λ nn where λ represents the wavelength of the received electromagnetic signal. From This relationship shows that a convenient way to position the antennas receivers is such that the size of the side of the triangle having the three antennas at the vertices is less than or equal to half the wavelength of the signal electromagnetic, so that the phase difference between the received signals is always included within a single full angle. So, in case that l = λ / 2 And - π ≤ θ ≤ π n it is possible to connect the electrical phase of the signals received by the receivers to the angle of arrival α of the signals themselves. In fact, we can calculate, for each of the angles relative electrics, the corresponding difference in path travelled by the signal transmitted by the transmitter: Δn = θn λ / 2π and then α = arcos (- θ λ / 2π l) α = 30° - arcsin (θ2 λ / 2π l) α = arcsin (θ λ / 2π l) – 30°. As known from trigonometry, for each of the above equations the solutions possible, for α, are 2 within an angle of 360°. So using at least two of the previous equations it is possible to determine the angle, α, sought. This calculation method, very simple from a theoretical point of view, presents problems related to unwanted interference effects between the three antennas A1, A2 and A3. In the real case, in fact, it happens that the mutual proximity of the antennas interferes with the received signal and, for certain angles of arrival, causes direct interference exerted by each antenna on the path of the signal directed towards the others antennas. In the antenna system, A1, A2, A3, the interference of each is described antenna on the others is practically always present. This interference can, for example for example, cause an increase in the phase delay of the signal directed onto it an antenna in case this antenna is obscured by another antenna. In in this case, when the electrical phase delay exceeds 180°, we have that a antenna that is on a longer signal travel path - and so it should have an electrical phase delay - it is instead in advance, making the data connected to the electrical phase impossible to interpret in a correct. To overcome this problem, the side of the triangle is reduced to whose vertices are the antennas, that is, the distance between the three antennas, A1, A2, is reduced and A3. In this way any phase losses due to interference, even if not being completely eliminated, they become such that they cannot lead to interpretations wrong phase sign. It is therefore necessary that the distance between the antennas, l, be such that: l < λ / 2. In a preferred embodiment of the sensor 11, 12 according to the present description which uses mono-conical antennas on ground plane or biconical, the distance l is preferably chosen between λ / 2 and λ / 4. In particular, choosing the distance l equal to approximately 80% of λ / 2 (or equal to 2λ / 5) it is possible to guarantee uniqueness of the relationship between electrical phases and corresponding geometric angles. The data relating to the electrical phase, θ, despite the above corrections, are still different from those theoretically expected. In fact, although it has been guaranteed the uniqueness of the solution and the phase is limited to 180 degrees, the angles are still distorted by mutual interference between the antennas. It is therefore necessary to compensate these deformations of the electrical phase in order to correctly resolve the angle of arrival, α, of the received signal. One way to make a correction is, for example, to use a table showing, for each angle of arrival, α, the electrical phase differences, θ, waited. An example is given below: Expected arrival angle θ Expected θ 1 2 α θ θ 1 11 21 α θ θ 2 12 22 α3 θ 13 θ 23 … … … αk θ 1k θ 2k This table can be filled in experimentally, during the development phase. initial of the system comprising the sensor and the TAG, measuring in correspondence of the TAG's arrival angles with respect to the sensor, α, given the phase differences electric, θ, correct. In this way, once a pair of electrical angles has been measured: θ , θ 1 2 we can proceed with the calculation of a cost function for each arrival angle possible listed in the table 2 2 ck = (θ2 - θ2k) + (θ1 – θ1k) . The index k for which we will have the lowest cost c will correspond to the angle of arrival, k αk, having maximum likelihood. The position data in the plane - obtained from the pair formed by the detected distance d, for example, via a UWB system and the angle of arrival, α, calculated as described previously – when it is transferred to polar coordinates on the plane it has errors different from the two coordinates, these coordinates being calculated with techniques different. The distance, in fact, is calculated, for example, as mentioned, with UWB technology based on the measurement of the time of flight and is affected by an error that can be expressed in terms absolute length. Angular measurements, on the other hand, present an error which, obviously, cannot be expressed. in terms of distance but in terms of angle width and it is quantitatively different from the error that affects the distance measurement since, to estimate the angle of arrival, the flight time is not measured by the transmitter but rather the phase difference on the set of three receiving antennas, A1, A2 and A3. While the position error due to the distance measurement is independent of the distance itself, the angular error results in an error, in terms of position, which becomes greater as the distance increases, this error being equal to the product of the angular error for the distance. In practice, it is as if the angular error is resolved, in terms of position, into a movement along an arc of a circle and then in a “fictitious” tangential movement. Basically the error on the measurement of the geometric angle can be assimilated to a tangential velocity component - which in reality is not present - and as such can be filtered and eliminated. Therefore, a filtering is applied to limit the aforementioned "fictitious" tangential velocity. in such a way as to make the determined trajectories closer to the real ones. The error of angle is corrected, in essence, by limiting the tangential displacement in the unit of time while not acting on the radial velocity. In detail, we consider having a series of n measurements performed on the distance and on the electrical phase of the signal exchanged between the second sensor 12 and TAG 10 or first sensor 11. Each measurement is therefore characterised by two parameters: measured distance and measured angle of arrival: d, α ii where the index “i” refers to the i-th point in the time sequence of the measurements taken, detected at the time instant you by the sensor, on the electromagnetic signal transmitted by the TAG (or the first sensor), that is, in other words terms, at the i-th measurement of the spatial position of the TAG (or of the first sensor). The angle α is the angle relative to the instant “i” once the operation has been carried out i_s filtering. For the purposes of the algorithm, let's assume that at the initial instant with i = 0 the filtered angle coincides with the measured one. α = α 0_s 0 For each point i ≥ 1, an estimated tangential velocity vti is calculated. For example, the calculation of the above tangential velocity can be done on the base of the equation: vti =(αi - αi-1_s) of where αi-1_s is the angle obtained with the previous measurement and subjected to filtering. The above filtering allows us to calculate a filtered geometric angle, αi_s, based on the calculated value of the tangential velocity, v, and a maximum value you acceptable value of the tangential velocity, v . For example, the value of the said angle tmax geometric filter can be calculated as follows: αi_s = αi if | vti | ≤ | vtmax |; α = α + K if | v | > | v |; i_s i-1_s ti tmax where K can, for example, be defined as follows: K = [|vtmax | (ti – ti-1) / di] sgn(vti) With the application of this tangential filtering we therefore limit the movement on the arc centered in the second sensor 12 and passing through the TAG 10 (or for the first sensor 11), thus reducing the noise due to the imprecision of the measurement of the angle of arrival. Knowledge of the position and evolution of the relative position between two objects, such as a barrier and a moving machine or vehicle, or a barrier and a person moving in the same area, allows for also know the relative speed between the two objects. Knowing this speed, together with the position, it therefore allows the behaviour of the detection systems so that they can provide alarms that are produced in a more intelligent way than simply detecting when a limit is exceeded certain threshold of distance. The fact that a target is at a certain distance, in fact, can determine whether or not a dangerous situation depending on whether the target is approaching or moving away. Also the relative position in terms of the angle between the two potential collisions have an influence on the actual danger of the distance detected. In fact, if a TAG is detected in an area where the vehicle or the operator is to which the TAG is associated cannot go, it is clear that in this case the alarm distance may be lower. Preferably, the sensors placed on the barriers are fixed, positioned with a specific default orientation that allows you to calculate the angle of arrival of a TAG or another sensor approaching, and geolocated. When an object mobile equipped with a TAG or a sensor enters the area surrounding the barrier, the fixed sensor mounted on the barrier constantly calculates, according to the modalities described previously, the distance and angle at which the moving object is approaches, thus determining its position precisely. As a result, the barrier can determine the position of a moving object equipped with a TAG or sensor that moves near the barrier itself and transmit it to the moving object itself; in this way, the moving object is informed of the interaction established with the barrier and knows its position relative, the distance and direction of travel with respect to the aforementioned barrier. Furthermore, the moving object is also able to know its absolute position if it is provided with a map showing the positions of the barriers fixed. In case the mobile object is a vehicle equipped with a screen (such as, for example, a tablet) for viewing georeferenced maps, advantageously the map of the activity area with the exact positions of the fixed barriers installed in the area may be displayed on board the vehicle, together with the exact location of the vehicle itself. Depending on the absolute position of the moving object and security protocols expected, the intervention method can be easily decided and varied. In the case the mobile object is, for example, a forklift, based on the interaction with the barrier the speed and / or direction of the forklift can be changed, they can be activated acoustic and / or optical warning devices etc. In the case of an operator on foot and the barrier is a controlled gate, you can provide to allow or block the opening of the gate if crossing it is deemed dangerous for the operator. Through the described system, the information acquired on the work areas and on the movable objects within them can be associated with an absolute position. This allows for standardized and universal management of the collected data, facilitating the exchange of information with other applications and managers. In the context of the described system, geolocation can be used both for receive information from the mobile object within an area of ​​interest, both for adapt the behavior of moving objects based on their position. By collecting data on the interactions between mobile vehicles and fixed barriers installed in a specific work area, it is possible to carry out appropriate analyses and post- processing to determine whether an area presents a higher risk level compared to other similar areas. Based on this evaluation, it is possible to decide to automatically mark the area with a corresponding risk level. As a result, maps are shared with all mobile objects in the area and related security policies can be updated automatically, making the implementation of updates to existing security policies and protocols in the area, immediate.

Claims

1. A crash protection system in an area of ​​interest comprising at least one transceiver or TAG device (10) and / or at least one first transceiver or sensor device (11), associated with an operator (13) or a vehicle (14) moving within said area of ​​interest and a second transceiver or sensor device (12) associated with a crash barrier (15) installed within said area of ​​interest, wherein said first sensor device (11), said second sensor device (12) and said TAG device (10) are tuned to the same operating radio frequencies and are capable of transmitting and receiving data through a radio frequency link; wherein said TAG (10) comprises: at least one radio frequency transceiver (29), at least one antenna (30) associated with said transceiver (29) and a controller (31) configured to appropriately drive said transceiver (29) in order to manage its transmission and reception sequences,wherein said first sensor (11) and said second sensor (12) comprise: at least three radio frequency transceivers (20, 21, 22, 40, 41, 42), at least three omnidirectional antennas (23, 24, 25, 43, 44, 45) on a plane normal to their axis and each associated with said at least three radio frequency transceivers (20, 21, 22, 40, 41, 42), a control unit (26, 46), configured to drive said transceivers (20, 21, 22, 40, 41, 42) wherein the control unit (46) of said second sensor (12) is configured to process the signals received from said TAG (10) and / or from said first sensor (11) so as to determine the distance, d, of said TAG (10) and / or of said first sensor (11) with respect to said second sensor (12) and the electrical phase, θ, of the signals received on each of said antennas (43, 44, 45) and further configured to calculate the geometric angle, α,of the approach of the TAG (10) and / or of the first sensor (11) to the second P023465IT-01 Notarbartolo & Gervasi SpA sensor (12) by processing the electrical phase, θ, of the signals received on said at least three antennas (43, 44, 45)., 2. System according to the preceding claim wherein the control unit (46) of said second sensor (12) is configured to trigger an alarm signal based on the detected value of said distance, d, and said geometric angle, α.

3. System according to one or more of the preceding claims wherein the control unit (46) of said second sensor (12) is configured to send to the control unit (26) of said first sensor (11) instructions for correcting the motion of the vehicle (14).

4. System according to one or more of the preceding claims wherein the control unit (46) of said second sensor (12) is configured to send to the control unit (26) of said first sensor (11) information on the relative position of the vehicle (14) with respect to the barrier (15).

5. System according to one or more of the preceding claims wherein said shock barrier (15) comprises geolocalisation means suitable for determining its geographical position.

6. System according to one or more of the preceding claims wherein said vehicle (14) comprises a screen for displaying georeferenced maps including indications of the position of said barrier (15) and indications updated in real time of the position of said vehicle (14).

7. System according to one or more of the preceding claims wherein said control unit (46) of said second sensor (12) is further configured to store the calculated values ​​of said distance, d, and said geometric angle, α, of approach.

8. System according to one or more of the preceding claims wherein said second transceiver or sensor device (12) is integrally integrated into said shock barrier (15).

9. System according to one or more of the preceding claims, wherein said crash barrier is selected from the group comprising crash posts, bollards, guardrails, gates, aligners, pedestrian parapets, and height limiters. P023465IT-01 Notarbartolo & Gervasi SpA 10. System according to one or more of claims 2 to 9 wherein said alarm is selected from the group comprising: actuation of an acoustic and / or sound alarm signal on board the vehicle on a collision course, actuation of the controls of the vehicle on a collision course so as to limit its speed or brake it.

11. System according to one or more of the preceding claims wherein the radio frequency connection between said first sensor (11) and / or said TAG (10) and said second sensor (12) is of the Ultra Wide Band, UWB type.

12. System according to one or more of the preceding claims wherein said control unit (46) of said second sensor (12) is adapted to determine said distance, d, by calculating the flight time of the signal between said TAG (10) and / or said first sensor (11) and said second sensor (12).

13. System according to one or more of the preceding claims wherein said second sensor (12) is configured to measure the distance, d, from said TAG (10) and / or from said sensor (11) by means of so-called Round Trip Time, RTT, techniques or by means of so-called Two Way Ranging, TWR, techniques.

14. System according to one or more of the preceding claims wherein said operating radio frequencies are between 2 GHz and 10 GHz.

15. System according to one or more of the preceding claims wherein said at least three antennas (23, 24, 25, 43, 44, 45) have a mutual distance between half and a quarter of the wavelength of the transmitted and received electromagnetic signal.

16. System according to the preceding claim wherein said mutual distance is approximately equal to 2 / 5 of the wavelength of the transmitted and received electromagnetic signal.

17. System according to one or more of the preceding claims wherein said second sensor (12) is configured to calculate the value of the geometric angle, α, of approach of the TAG (10) and / or of the first sensor (11) to the second sensor (12) via a table that links the values ​​of geometric angles, α, to the values ​​of electrical phase, θ, of the electromagnetic signals received on said at least three antennas (43, 44, 45) during the initial setup phase. P023465IT-01 Notarbartolo & Gervasi SpA 18. System according to one or more of the preceding claims wherein the antennas (43, 44, 45) of said second sensor (12) are monoconical antennas (60, 61,62) and mounted on a circular ground plane (63).

19. System according to one or more of claims 1 to 17 wherein the antennas (43, 44, 45) of said second sensor (12) are bi-conical antennas (50, 51, 52) mounted on a base (53) of non-conductive and radiolucent material.

20. Barrier (15) equipped with a sensor device (12) comprising at least three radio frequency transceivers (40, 41, 42), at least three omnidirectional antennas (43, 44, 45) on a plane normal to their axis and each associated with said at least three radio frequency transceivers (40, 41, 42), a control unit (46), configured to drive said transceivers (40, 41,42) and an external interface (27), and configured to process the signals received from a TAG (10) and / or from a first sensor (11) so as to determine the distance, d, of said TAG (10) and / or said first sensor (11) with respect to said second sensor (12) and the electrical phase, θ, of the signals received on each of said antennas (43, 44, 45) and further configured to calculate the geometric angle, α, of approach of the TAG (10) and / or of the first sensor (11) to the second sensor (12) by processing the electrical phase, θ, of the signals received on said at least three antennas (43, 44, 45),and wherein said control unit (26) is configured to calculate said distance, d, and said geometric angle, α, of approach so as to determine a probable impact between a vehicle on a collision course and the barrier, and to generate an alarm in the event that the probable impact is determined., 21. Barrier (15) according to claim 20 comprising a geolocalisation device.

22. Barrier (15) according to claim 20 or 21 comprising network connection means.