Abstract
The invention relates to a system and method for detecting vibrations on the periphery of an optical fibre, which is divided into five subsystems that are connected together. First, a light-source subsystem (6) generates light, which is transmitted through an optical fibre subsystem (2). Then, speckle interference patterns generated in the optical fibre are read using a CMOS micro camera subsystem (5). Subsequently, the information is analysed by a processing subsystem (7), producing an alarm signal that is notified to the outside by means of a communications subsystem (1).
Claims
1. A system that allows the detection of vibrations on the periphery of an optical fiber characterized by being light, economical, fast and with low energy consumption, which comprises: a. a fiber optic system (2) that detects external disturbances and comprises an optical fiber sensor cable (21) and connectors (22) which are connected to both the light source system (6) and the CMOS micro-camera system (5); b. a light source system (6) including a voltage stabilizing stage, a light source and an activation control stage; wherein said system generates a light that is transmitted through the fiber optic system (2) to which it is connected; c. a CMOS micro-camera system (5 comprising a CMOS sensor that detects the light received from the fiber optic system (2) and a digital signal processing block which conditions the information of each pixel, represents them digitally and sends said signals with the coordinates of the speckled interference patterns within the CMOS array (51) to the processing system (7), said processing block is fast allowing the post processing in (7) to be much less; d. a processing system (7) implemented in a lightweight micro-controller, in which the processing is done through the analysis of a speckled type interferometer pattern to determine the intensity of the disturbance generated in the fiber optic sensor cable (21), said fast and low-consumption processing includes: receiving the coordinates of the speckled interference patterns from the CMOS micro-camera system (5), calculating the displacement variables of each of the speckles, performing the summation of the magnitudes of the displacements of all the speckles (14), calculate the final displacement (df) in a sampling period by making an integral of the sum of the velocities of all the speckles (FIG. 15c), compare the final displacement with different thresholds, so that can determine a real event or a false event, and send alarm signals to the communication system (1); e. a communication system (1) consisting of a wired communication subsystem (10) and a wireless communication subsystem, which connect the processing system (7) with the outside by sending alarm signals to it and receiving configuration parameters for the processing system (7).
2. The system of claim 1, wherein said fiber optic sensor cable (21) is a double-stranded duplex type and the two ends of the optic fiber (21) are joined by a mechanical joint (23).
3. The system of claim 1, wherein said because the fiber optic sensor cable (21) is simplex type, composed of a filament, wherein said fiber turns around on itself connecting at one end to the connector of the light source system (6) and at the other end to the CMOS micro-camera system (5).
4. The system of claim 1, wherein said connectors (22) of the fiber optic system (2) are of the SMA-M type.
5. The system of claim 1, wherein said light source system (6) comprises a laser light emitting diode.
6. The system of claim 1, wherein said wireless communication subsystem comprises a WiFi communication subsystem (8) and an 800 MHz-900 MHz communication subsystem.
7. The system of claim 1, wherein said wired communication subsystem (10) includes a USB output and a dry contact output.
8. The system of claim 1, wherein the light source system (6), the CMOS micro-camera system (5), the processing system (7) and the communication system (1) are placed in a mechanical housing (11) which is coupled through SMA-F connectors (3) (4) to the fiber optic system (2).
9. The system of claim 8, wherein said mechanical housing (11) is composed of a CMOS camera holder base (12), a CMOS camera and laser coupling base (13), an SMA-F connector of the CMOS micro-camera system (3) and an SMA-F connector from the light source system (4).
10. A method for detecting of vibrations in the periphery of an optical fiber and is implemented in a low-cost and light micro-controller, said method comprises the stages of: a. Reading the speckled pattern of disturbances through the CMOS micro-camera system (5) that makes the projection of the speckles (14) over the CMOS array (51); b. Sending signals to the processing system (7) from the CMOS micro-camera system (5),where said signals indicate the coordinates of the disturbance speckles within the CMOS array (51); c. Calculating in the processing system (7) the displacement variables of each of the speckles by variables (x, y), when the system starts for the first time, these variables are automatically established with their initial value, this value is the position of all the speckles detected at a zero instant, at position (0,0) which will be the reference point in the calculation; d. Performing the summation of the displacement magnitudes of all the speckles (14); e. Calculating the final displacement (df) in a sampling period by performing an integral of the summation of the velocities of all the speckles. The final displacement obtained depends on all the displacement of the speckles (14) calculated in a determined period of time and allows to know how strong the external disturbance was applied; f. Starting the decrement logic (71) of the variables that contain the value of the coordinates of the speckles (14). This decrement begins in the opposite direction to the increment when the time to take the displacement sample finishes, and it is done until the variable responsible for obtaining the data of the magnitude of the vector with coordinates (x, y) returns to its initial position (0,0); g. Comparing the information obtained on the final displacement with different specified thresholds so that it can be determined which displacement levels of the speckles (14) generate a real event or a false event; it is determined if it is a real event or a false alarm by comparing with the reference data; i. Sending signals representing the type of event detected from the processing system (7) to the communication system (1).
11. The method of claim 10, further comprising: a technique for monitoring the quality of the image obtained by the CMOS array (51) and processed by the processing system (7), which consists of determining the level of optical intensity received by the light source (6) averaging the optical intensity of all the pixels of the CMOS array (51), where this information allows diagnosing the correct alignment of the optical coupling, and inferring about the state and correct operation of the optical fiber (21) and the light source (6).
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0052] Aiming to facilitate the understanding of this invention, a detailed description of the here presented drawings will be made:
[0053] FIG. 1 is a block diagram, which represents the main systems of the invention.
[0054] FIG. 2 is a representation of the top view with mechanical housing transparency of the device.
[0055] FIG. 3 is a representation of the top view without mechanical housing.
[0056] FIG. 4 represents the bottom view of the top view without mechanical housing of the device.
[0057] FIG. 5 is a representation of the external view of the mechanical housing from different angles.
[0058] FIG. 6 is a representation from the way in which the optical fiber system connects to the mechanical housing.
[0059] FIG. 7 represents the way in which the fiber optical sensor wire connects to the mechanical junction.
[0060] FIG. 8 represents the installations with different types of optical fibers. FIG. 8a represents the production of the invention in which simplex optical fiber was used. FIG. 8b represents the production of the invention in which duplex optical fiber was used.
[0061] FIG. 9 represents the detail of the coupling mechanics of the two SMA connectors.
[0062] FIG. 10 represents the visual detail of the lateral side from the mechanical housing with the USB connector and the dry contact connectors.
[0063] FIG. 11 represents the three-dimensional detail of the base of the CMOS camera holder.
[0064] FIG. 12 represents the three-dimensional detail of the base of the laser coupling and of the CMOS camera.
[0065] FIG. 13 represents the detail of the CMOS camera micro system.
[0066] FIG. 14 represents the CMOS array with the specks, when disturbed.
[0067] FIG. 15 corresponds to the formula required to calculate the final displacement.
[0068] FIG. 16 represents the processing which is made after the disturbance of the optical fiber.
[0069] FIG. 17 is a block diagram with the main stages of the light source system.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT
[0070] The following detailed description of the invention refers to the here attached figures. Although the description already includes feasible examples, others are also possible and changes of the performance can also be made. Changes to the invention are possible and should be considered by those who are well versed. However, many changes could lead to results that go beyond the scope of the invention.
[0071] FIG. 1 shows a block diagram which represents the main systems of the invention. The light source system (6) generates light, which is transmitted through an optical fiber system (2). This system detects the disturbances from the exterior and shows them through light pattern changes.
[0072] FIG. 2 is a representation of the top view with transparency of the mechanical housing (11). In the figure the coupled parts of the mechanical housing are illustrated (11). The mechanical housing consists of one CMOS camera holder base (12), one laser coupling base and CMOS camera (13), one SMA-F connector (3) of the CMOS micro-camera system (5) and the SMA-F connector (4) of the light source system (6).
[0073] FIG. 3 represents the top view without the mechanical housing of the device (11). In this figure it is illustrated how the systems, which are located inside the mechanical housing (11), are distributed. It is evidenced that the light source system (6) is located in the same side as its respective SMA-F connector (4). In this way, the mechanical coupling and the wiring connection are facilitated. Furthermore, it is shown that the CMOS micro-camera system (5) is located near to the SMA-F connector (3) of the CMOS micro-camera system (5). Thus, the connection between the both elements is favored. Additionally, the process system (7) is located in the center of the mechanical housing because it must have connections with the rest of the systems located inside the mechanical housing (11). Moreover, it is illustrated that the wire communication subsystem (10) corresponds to one USB output and one dry contact output. These subsystems are located at one end of the device in order to favor the communication with the exterior.
[0074] FIG. 4 represents the inferior view without the mechanical housing of the device. Here is shown that the WiFi communication subsystem (8), which is connected to the inferior view of the electronic card to optimize the space.
[0075] FIG. 5 represents the exterior view of the mechanical housing (11) from different angles. Here is depicted that the housing is made of aluminum and it has a rectangular shape with approximate dimensions of 12 cm long, 3 cm high and 10 cm wide.
[0076] In FIG. 6 the way in which the optical fiber system (2) is connected to the mechanical housing (11) is shown. In the figure are depicted the SMA-M connectors (22), which are connected to the ends of the optical fiber sensor wire (21). The SMA-F connector of the CMOS micro-camera system (3) and the light source system (4) are also shown.
[0077] FIG. 7 represents the way in which the mechanical coupling (23) is connected to the ends of the duplex optical fiber sensor wire (21). This coupling (23) allows a permanent binding between the ends of the optical fiber. Moreover, the coupling (23) has a good optical performance, determined by a low attenuation, a minimal reflectance and a high mechanical resistance.
[0078] FIG. 8a shows the simplex optical fiber wire (21). Here it is shown the single filament which covers the mesh to protect it. Furthermore, the figure illustrates one watertight box (15), which is used for the outside and in which the mechanical housing (11) is located
[0079] In FIG. 8b a duplex optical fiber wire (21) is used the installation. The two filaments of the fiber are shown, which covers the mesh to protect it. Moreover, the figure shows a multi-pair cable (16) which allows the device supply while connecting the dry contact outputs (10), which has the device to notify the alarm.
[0080] FIG. 9 presents the SMA-M connector (22) coupling mechanics in detail. This is coupled to the optical fiber wire (21) and its end is threaded with the SMA-F (3)(4) connector, which is secured to the mechanical housing (11) and has the shape of a threaded screw.
[0081] In an embodiment form presented in the FIG. 10, the detail of the lateral view of the mechanical housing (11) is shown, where the outputs of the wired communication subsystem (10) can be observed. On the one hand, the USB connector output (101) is shown. This is a communication port used to configure the system, and alternatively, to allow feeding the device with energy supply. In addition, it shows dry contact relay out terminals, which include: a normally-open terminal—NA (102), a common terminal—COM (103), and a normally-closed terminal—NC (104). Finally, the FIG. 10 shows the terminals to feed the device, corresponding to the ground terminal—GND (161), and the voltage terminal—VCC (162).
[0082] In a preferred embodiment of the invention, shown in the FIG. 11, the three-dimensional detail of the CMOS camera holder base (12), which mechanically holds the CMOS camera, is presented. Besides, it has a rectangular slot in the center, where the CMOS camera is coupled, and at its ends it has two rectangular couplings, allowing the connection with the electronic card. This base is built in ABS or aluminum.
[0083] In an embodiment shown in the FIG. 12, the three-dimensional detail of the laser and CMOS camera coupling base (13), which mechanically holds the CMOS camera holder base (12) and the laser diode, is presented. Additionally, in its internal face it has in the center two orifices allowing the connection of the CMOS micro-camera system (5) and the light source system (6) with the SMA-F connectors. In its external face, the SMA-F (3) (4) through which the optical fiber system will be coupled (2) are installed. This base is built in ABS or aluminum.
[0084] The FIG. 13 represents the detail of the CMOS micro-camera system (5), consisting of an active pixels sensor built with Complementary metal-oxide semiconductor (CMOS). Said sensor detects the light traversing the CMOS array (51) in the same sensor. Additionally, the CMOS sensor has a column decoder (53) and a row decoder (52) to translate the information, and also has a digital signal processor that digitizes the information of the light recorded by the CMOS array (51).
[0085] The FIG. 14 shows the CMOS array (51) photosensitive with the specks (14) when it is disturbed. The grid presented in the Cartesian plane corresponds to the CMOS array (51), where each cell represents a photosensitive pixel. Each speckle (14) presented in the CMOS array (51) belongs to an external disturbance applied to the optical fiber in a certain time. The arrows towards some specks represent the displacement magnitudes that each speckle has regarding the starting point (0,0). The summation of said displacements provides the require information to estimate how strong the disturbance applied to the optical fiber was.
[0086] The FIG. 15 correspond to the formulas to calculate the final displacement variable in the processing system (7). The FIG. 15a corresponds to the formula to calculate the summation of the magnitudes of all the specks displacements (14). Then, the FIG. 15b corresponds to the formula to calculate the summation of the magnitudes of all the speeds resulting from dividing the displacements summation by the sampling time. Finally, the FIG. 15c corresponds to the formula to calculate the final displacement (df) with an integral of the summation of the speeds of all the specks. The final displacement is the accumulated value that serves as a reference to analyze the disturbance magnitude, allowing to estimate how strong the external disturbance applied was.
[0087] The FIG. 16 represents the processing done further to the disturbance of the optical fiber. Once the time to take the sample of the displacement is finished, the logic of the decrement (71) starts in the processing system (7), where the values of the variables containing the information of the speckle coordinates (14) are decreased. This decrement continues until the variable that obtains the vector magnitude data reaching a point of coordinates (x, y), returns to its initial position (0,0), which corresponds to the logic of reference point 0 (72).
[0088] The FIG. 17 is a block diagram that shows the main stages of the light source system. The voltage stabilizing stage guarantees that the electrical supply has the required voltage quality and features. The coherent light source stage corresponds finally to the light emitting source. The electronics activation control stage analyze if the system requirements (e.g. electrical supply stability and activation configuration parameters) are being met. Only after evaluating these conditions, the activation control stage will be able to send a valid activation signal to the coherent light source stage to start the operation.
