KR101499398B1 - Impact point monitoring system using intensity-based fiber optic sensor - Google Patents

Abstract

An impact position estimation system of the present invention, which can easily estimate an impact position by using optical loss, comprises: a light source to emit light; an optical fiber to transmit the light emitted from the light source; two or more mandrels arranged along the optical fiber; a photodetector to detect the light transmitted from the optical fiber; and a computer to receive a signal from the photodetector, to measure the amount of optical loss generated from the optical fiber through the received signal, and to identify an impact position by using the measured amount of optical loss. The optical fiber and the mandrels are positioned inside a housing. When an impact is applied to any position of the housing, the mandrel is moved by the impact, the optical fiber is bent by pressure of the mandrel, and the optical loss is generated in the optical fiber by the bending of the optical fiber. The system of the present invention can easily estimate the impact position using the optical loss caused by the bending of the optical fiber.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an impact position monitoring system using an optical intensity-

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an impact position estimation system using a light intensity type optical fiber sensor, and more particularly, to an impact position estimation system capable of estimating an impact position using optical loss due to bending of an optical fiber.

Since the optical loss-type Guam fiber sensor is based on the optical loss due to the bending of the optical fiber, it is called a bendable optical fiber sensor. When a small-diameter bend is applied to a straight-line single-mode fiber, the typical loss of optical power is caused by pure bend loss and mode transition loss.

The pure bending loss is the refractive index of the core is n _co and the refractive index of the cladding is n _d . In the bent region, the incident angle of the single transverse mode with respect to the incident wave of wavelength? It is a loss phenomenon that can not be guided but leaks out.

Fig. 1 is a view for explaining the mechanism of pure bending loss.

FIG. 1 shows the mechanism of this pure bending loss, in which a transverse mode of power p ₀ propagates along the optical fiber axis without loss at a straight line before bending is applied to the optical fiber.

가 된다. 이러한 파워는 굽힘 광섬유의 곡률 r_b와 접촉하는 호의 길이 s에 따른 진행한 후의 순수 굽힘 손실에 의해 없어지고, 남은 진행 파워 P(s)에 대한 표현은 아래 수학식과 같다.However, if there is bending, this part is bent into a circle with radius r _b and angle Φ. The mode wavefront in this bend region will then propagate at a rate that depends linearly on the radiation distance from the center of curvature of the bend. Mode, the speed of light propagating through each of the phase velocity (angular phase velocity) and the optical fiber in the wave front (each group velocity, angular group velocity) is in the radial position of the specific values r _c larger lateral mode intensity distribution than that is equal to (Fig dark in 1 The region of the power P _c corresponding to the region). The mode intensity distribution disappears by itself and propagates from the separation point to the tangential path and is scattered. Then, except for the power lost due to pure bending loss,

. This power is eliminated by the progressive pure bending loss according to the length s of the arc in contact with the curvature r _b of the bending optical fiber, and the expression for the remaining traveling power P (s) is as follows.

Here, V, U, and W are expressed by the following equations.

이다. And,

to be.

이다. β의 표현에서 k0는 진공 중에서의 전파상수이며, θ는 광섬유 코어 내에서 코어와 클래딩의 경계로 입사하는 광선이 경계면의 입사점에서 세운 법선과 이루는 각도이다. 이 β는 n_dk<β<n_cok을 만족한다.In this equation, a is the core radius, k is the propagation constant, k = 2π / λ, and the transverse propagation component of the optical fiber,

to be. In the expression β, k0 is the propagation constant in vacuum, and θ is the angle formed by the ray incident on the boundary between the core and the cladding in the optical fiber core, with the normal perpendicular to the incident point at the interface. This β satisfies n _d k <β <n _co k.

Mode switching loss occurs when the mode shape of the straight portion and the bent portion of the optical fiber are different from each other.

2 is a view for explaining a mode switching loss mechanism.

As shown in Fig. 2, the center maximum value of the mode in the bending region is shifted to the outside of the radius by the distance? In comparison with the straightly extending optical fiber region. At junction 1 between the straight and bent portions of the optical fiber, a portion of the incident power travels to the bending region and the remaining power couples to the radiation mode in the cladding and its outer coating layer region. This progression and the power coupling process in the radiation mode occurs at the junction 2 where the optical fiber bends and straightens again.

The result of total mode switching loss due to bending is calculated by summing the losses at two intersections. Also, the change of the mode also affects the increase of the pure bending loss as the power corresponding to the dark region in Fig. 2 increases. In the case of a long region where the bending region where this loss occurs corresponds to half of the circumference (half of the circumference), since the pure bending loss is larger than the mode switching loss in the two main loss mechanisms described above, You can explain trends. And the model with the geometric structure causes the optical loss described above.

Korean Patent No. 10-1041380

An object of the present invention is to provide an impact position estimation system for estimating an impact position by measuring the amount of light loss at each position by changing a bending loss model at various points using optical loss of optical fibers.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an impact position estimation system including: a light source for transmitting light; an optical fiber for transmitting light emitted from the light source; at least two mandrels disposed along the optical fiber; And a computer for receiving a signal from the photodetector, measuring a light loss amount generated in the optical fiber through the optical detector, and determining a position where an impact is generated by using the measured optical loss, Wherein at least two of the mandibles are located inside the housing and when the impact is applied to a position of the housing, the mandrel is moved by impact and bending occurs in the optical fiber due to the pressure of the mandrel, Optical loss occurs.

In an embodiment of the present invention, the amount of light loss generated in the optical fiber varies depending on the impact position applied to the housing in a manner that the intervals between the mandibles are different, and the computer uses the optical loss amount generated in the optical fiber It is possible to determine the location of the impact in the housing.

In another embodiment of the present invention, the amount of optical loss generated in the optical fiber varies depending on the impact position applied to the housing in a manner that the mandrel having a different radius is arranged, and the computer uses the optical loss amount generated in the optical fiber It is possible to determine the location of the impact in the housing.

In another embodiment of the present invention, the amount of optical loss generated in the optical fiber varies depending on the impact position applied to the housing in a manner that the number of mandrels is varied according to each position, It is possible to determine the location of the impact in the housing by using the amount of loss.

In another embodiment of the present invention, the total amount of optical loss varies depending on the impact position applied to the housing by varying the number of optical fibers passing through the optical fiber at each position, and the computer calculates the total amount of optical loss It is possible to determine the position where the impact occurs. At this time, two or more optical fibers having a bending model of the same shape can be used. Alternatively, the number of optical fibers may be varied at each position by using one optical fiber so that the total amount of optical loss varies depending on the impact position applied to the housing.

According to the present invention, it is possible to easily estimate the location of an impact by using light loss caused by bending of the optical fiber.

In addition, according to the present invention, since it is possible to estimate not only the impact, but also the position where the impact occurs, it is expected to be very useful in a related field requiring impact detection or shock detection.

Fig. 1 is a view for explaining the mechanism of pure bending loss.
2 is a view for explaining a mode switching loss mechanism.
3 is a view showing a bending loss model.
4 is a cross-sectional view of a portion where an optical fiber and a mandrel are formed in the case where there is no direct external force influence in an impact position estimation system using an optical fiber.
5 is a cross-sectional view of a portion where an optical fiber and a mandrel are formed in the case where there is an influence of a direct external force in an impact position estimation system using an optical fiber.
Fig. 6 is a diagram illustrating the types of bending models for differentiating optical loss.
FIG. 7 is a diagram illustrating a configuration for distinguishing impact positions according to bending models according to positions.
8 is a view showing an impact position estimation system for determining impact positions by changing the number of optical fiber cables according to positions according to an embodiment of the present invention.
9 is a view showing an impact position estimation system for determining impact positions by changing the number of optical fiber cables according to positions according to another embodiment of the present invention.
FIG. 10 is a view showing a configuration of an impact position estimation system using optical fibers according to another embodiment of the present invention.
11 is a block diagram illustrating the structure of an impact position estimation system using optical fibers according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted in an ideal or overly formal sense unless expressly defined in the present application Do not.

In the following description of the present invention with reference to the accompanying drawings, the same components are denoted by the same reference numerals regardless of the reference numerals, and redundant explanations thereof will be omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

The present invention relates to an impact position estimation system using optical fibers.

3 is a view showing a bending loss model.

As shown in FIG. 3, a geometric structure that causes bending to occur using a plurality of mandrels, and a structural mechanism is substituted into the optical loss theory as follows.

When the bending angle is substituted for the length of the bending arc (s = r?), Equation (1) is expressed by the following equation.

Therefore, the optical loss changes depending on the bending angle.

The parameters for determining the amount of bending loss of the optical fiber by equations (4) and (5) are the diameter r of the mandrel and the distance D between the mandrel. Therefore, in the present invention, it is possible to manufacture a sensor for estimating a position receiving an external force or pressure. In other words, it is possible to design a system that estimates the position received by external force by controlling the distance between the diameter and the mandrel for each position receiving the force.

11 is a block diagram illustrating the structure of an impact position estimation system using optical fibers according to an embodiment of the present invention.

Referring to FIG. 11, the impact position estimation system of the present invention includes a light source 110, an optical fiber 120, a photo detector 130, and a computer 140.

The light source 110 serves to transmit light. For example, the light source 110 may use a laser diode (LD).

The optical fiber 120 transmits light emitted from the light source 110.

The photodetector 130 serves to detect the light transmitted from the optical fiber 120. For example, the photodetector 130 may use a photodetector (PD).

The computer 140 receives a signal from the photodetector 130, measures the amount of light loss occurring in the optical fiber 120, and uses the measured amount of light to determine the location of the impact.

The optical fiber 120 and the two or more mandrels 310 are located inside the housing and when the impact is applied to any position of the housing the mandrel 310 is moved by the impact and the optical fiber Bending occurs in the optical fiber 120, and optical loss occurs in the optical fiber due to such bending.

The computer 140 measures the amount of light loss generated in the optical fiber 120, and uses the measured optical loss to determine the location of the impact.

In an embodiment of the present invention, the amount of light loss generated in the optical fiber 120 varies depending on the impact position applied to the housing in a manner that the distances between the mandibles 310 are different, and the computer 140 controls the optical fiber 120, The location of the impact in the housing can be determined using the amount of light loss occurring in the housing.

In another embodiment of the present invention, the computer 140 may adjust the optical loss of the optical fiber 120 by varying the amount of light loss generated in the optical fiber 120 according to the impact position applied to the housing by arranging the mandrel 310 having different radii, The location of the impact in the housing can be determined using the amount of light loss occurring in the housing.

In another embodiment of the present invention, the amount of light loss generated in the optical fiber 120 according to the impact position applied to the housing may be varied by arranging the number of mandrels at different positions, and the computer 140 may control the optical fiber 120 The position of the impact in the housing can be determined.

In another embodiment of the present invention, the total amount of optical loss according to the impact position applied to the housing may be varied by varying the number of optical fibers 120 passing through each position, and the computer 140 may use the total amount of optical loss, The position where the impact occurs can be determined. In the present invention, two methods are proposed for implementing this embodiment. First, a method is implemented using two or more optical fibers 120 having a bending model of the same shape. Figs. 8 and 9 show an example of the structure. In the second method, the optical fiber 120 is used to vary the number of paths of optical fibers for each position, thereby varying the total amount of light loss depending on the impact position applied to the housing. FIG.

4 is a cross-sectional view of a portion where an optical fiber and a mandrel are formed in the case where there is no direct external force influence in an impact position estimation system using an optical fiber.

5 is a cross-sectional view of a portion where an optical fiber and a mandrel are formed in the case where there is an influence of a direct external force in an impact position estimation system using an optical fiber.

4 and 5, a mandrel 310 is disposed along the optical fiber 120. As shown in FIG. In the present invention, two or more mandrels 310 are disposed along the optical fiber 120.

5, micro-bending of the optical fiber 120 occurs due to an external force and optical loss occurs.

As shown in FIGS. 4 and 5, when an external force is applied, it is possible to determine whether a pressure is generated due to light loss. Therefore, it is possible to know the existence or nonexistence of pressure at each point by using different design variables at various points.

As a concrete implementation method for estimating the impact position, first, a method of distinguishing the impact position according to the interval length between the mandrels determining the bending angle, and second, a method of distinguishing the impact position by the difference of the radius of the mandrel And third, a method of distinguishing the impact position by using the difference in the total number of the mandibles. In addition, the bending light loss is different according to the position where each impact occurs.

Fig. 6 is a diagram illustrating the types of bending models for differentiating optical loss.

FIG. 7 is a diagram illustrating a configuration for distinguishing impact positions according to bending models according to positions.

Referring to FIG. 7, the bending model can be configured for each position, and the position of the bending model can be determined when a pressure (pressing) occurs at one point.

The fourth method for estimating the impact position in the present invention is a method for determining the impact position through the total amount of optical loss by using the difference in the number of optical fiber cables in the same shape bending model.

8 is a view showing an impact position estimation system for determining impact positions by changing the number of optical fiber cables according to positions according to an embodiment of the present invention.

9 is a view showing an impact position estimation system for determining impact positions by changing the number of optical fiber cables according to positions according to another embodiment of the present invention.

In Figs. 8 and 9, an LD is used as the light source 110, and PD is used as the photodetector 130. Fig.

In FIG. 8, the system can be configured with one light source 110 and four photodetectors 130 to detect impact positions at four locations.

8, eight optical fibers pass in the first position, six optical fibers pass in the second position, four optical fibers pass in the third position, and two optical fibers pass in the fourth position.

In FIG. 9, the system can be configured with four light sources 110 and four photodetectors 130 to detect impact positions at four positions.

In FIG. 9, eight optical fibers pass in the first position, six optical fibers pass in the second position, four optical fibers pass in the third position, and two optical fibers pass in the fourth position.

As shown in Figs. 8 and 9, it is possible to classify the impact position through the total amount of optical loss due to the difference in the number of optical fiber cables in the bending model of the same shape.

In the present invention, the light source 110 outputs relatively high intensity light, the light proceeds along the optical fiber 120, and the light intensity is measured by the optical detector 130.

In the present invention, when a loss due to bending of an optical fiber cable is generated, the intensity of the light is reduced, and a point where light is lost is estimated by using the number of cables to find a point where an external force is generated.

8 and 9, an optical fiber cable 120 is applied in a U-shape so that the light source 110 and the optical detector 130 can be disposed on one side in order to simplify the system. As a result, the amount of light loss increases, and the impact position can be more clearly distinguished.

The fifth method for estimating the impact position in the present invention is a method for determining the impact position by measuring the amount of optical loss by varying the number of paths of optical fiber cables passing through each position using a single optical fiber cable.

FIG. 10 is a view showing a configuration of an impact position estimation system using optical fibers according to another embodiment of the present invention.

Referring to FIG. 10, a system in which different amounts of optical fibers pass through each position using one optical fiber 120 can be used to measure light attenuation at a specific position. That is, one optical fiber passes in a first position, three optical fibers pass in a second position, five optical fibers pass in a third position, and seven optical fibers pass in a fourth position.

In the graph shown in FIG. 10, it can be seen that the amount of light loss is different for each position.

In the present invention, it is possible to determine a larger number of optical loss amounts per position by combining the above-mentioned five methods.

While the present invention has been described with reference to several preferred embodiments, these embodiments are illustrative and not restrictive. It will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.

110 light source 120 optical fiber
130 photodetector 140 computer
310 mandrel

Claims (7)

delete A light source for emitting light;
An optical fiber for transmitting light emitted from the light source;
At least two mandrels disposed along the optical fiber;
A photodetector for detecting light transmitted from the optical fiber; And
And a computer for receiving a signal from the photodetector, measuring a light loss occurring in the optical fiber through the photodetector,
The optical fiber and the two or more mandrels are located inside the housing. When the impact is applied to any position of the housing, the mandrel moves by impact, and the bending of the optical fiber occurs due to the pressure caused by the mandrel. A light loss occurs in the optical fiber,
The optical loss of the optical fiber varies depending on the position of the impact applied to the housing,
Wherein the computer identifies the location of the impact in the housing by using the amount of light loss occurring in the optical fiber.
delete A light source for emitting light;
An optical fiber for transmitting light emitted from the light source;
At least two mandrels disposed along the optical fiber;
A photodetector for detecting light transmitted from the optical fiber; And
And a computer for receiving a signal from the photodetector, measuring a light loss occurring in the optical fiber through the photodetector,
The optical fiber and the two or more mandrels are located inside the housing. When the impact is applied to any position of the housing, the mandrel moves by impact, and the bending of the optical fiber occurs due to the pressure caused by the mandrel. A light loss occurs in the optical fiber,
The number of mandrels is varied according to each position so that the amount of light loss generated in the optical fiber according to the impact position applied to the housing is changed,
Wherein the computer identifies the location of the impact in the housing by using the amount of light loss occurring in the optical fiber.
A light source for emitting light;
An optical fiber for transmitting light emitted from the light source;
At least two mandrels disposed along the optical fiber;
A photodetector for detecting light transmitted from the optical fiber; And
And a computer for receiving a signal from the photodetector, measuring a light loss occurring in the optical fiber through the photodetector,
The optical fiber and the two or more mandrels are located inside the housing. When the impact is applied to any position of the housing, the mandrel moves by impact, and the bending of the optical fiber occurs due to the pressure caused by the mandrel. A light loss occurs in the optical fiber,
The total amount of optical loss according to the impact position applied to the housing is varied by changing the number of the optical fibers passing through each position,
Wherein the computer identifies the location of the impact in the housing using the total amount of light loss.
The method of claim 5,
Wherein the optical system is implemented using at least two optical fibers having a bending model of the same shape.
The method of claim 5,
Wherein the number of optical fibers is varied in each position by using one optical fiber so that the total amount of optical loss according to the impact position applied to the housing is varied.

Images