CN201844898U - Temperature self-compensating fiber grating stem force transducer - Google Patents

Abstract

The utility model relates to an optical fiber grating rod force sensor, which is characterized in that two rectangular hollow rectangular frames associated with parallel beams go forward and are vertically fixedly connected to each other, and the first optical fiber grating strain sensor is pasted parallel to the rectangular hollow rectangular frame on the second On a plane of an associated parallel beam, the second optical fiber grating strain sensor is pasted on a plane of the second associated parallel beam parallel to the rectangular hollow rectangular frame, and the first optical fiber grating strain sensor is connected in series with the second optical fiber grating strain sensor connect. The sensor has the characteristics of anti-electromagnetic interference, high precision, fast dynamic response, small size, light weight, simple structure, etc., and is more reliable, stable and simple; in addition, the cost of the temperature self-compensating fiber grating rod force sensor is relatively low. In a relatively narrow space, the temperature compensation of the sensor can be realized while measuring the force of the elastic element.

Description

A temperature self-compensating fiber grating rod force sensor

technical field

The invention relates to an optical fiber grating rod force sensor, which can eliminate the influence of temperature on the optical fiber grating sensor and belongs to the field of optical fiber sensing.

Background technique

Fiber Bragg grating sensing is a new type of sensing principle. It uses light waves as signal carriers and uses wavelength modulation. It is not affected by light intensity and has stable signals. It has good sensing performance in various occasions of structural engineering. The temperature and strain sensor made by using the fiber grating principle can effectively measure the temperature and strain of the structure, and the manufactured sensor has the advantages of small size, high measurement accuracy, anti-electromagnetic interference, corrosion resistance, good reliability and stability, and good durability. Etc.

In the rod force sensing system, the traditional rod force sensing principle mostly adopts the transformation principle of resistance strain type. The rod force load is converted into surface strain by the elastic element, the strain is sensed and tested by the resistance strain gauge, and then the change of the resistance strain gauge is converted into an electrical signal output by electronic measurement technology. Although this traditional resistance strain type rod force sensor can meet the sensing requirements in general applications, this teletype sensor has its inherent defects: there are many limitations in measurement accuracy and reliability. For example, because the resistivity of the resistance strain gauge will change greatly under the action of temperature, for example, when the temperature changes from -55°C to +60°C, the resistance value of the semiconductor resistance strain gauge will change from more than 600 ohms to about 1300 ohms, Its temperature coefficient of resistance is greater than 700×10-6/°C; although the temperature coefficient of resistance of metal resistance strain gauges is smaller, its sensitivity coefficient is 100 times smaller than that of semiconductor resistance strain gauges. In electrical measurement technology, although zero temperature compensation technologies such as thermistor compensation, series-parallel resistance compensation, and active circuit segment compensation can be used to reduce the zero output drift within a certain range, due to technical limitations, This type of rod force sensor based on resistance strain can not reach a high level of precision and sensitivity; it cannot protect against lightning, electromagnetic interference (EMI) and electromagnetic shock (EMP).

In view of the defects of traditional rod force sensors, fiber grating rod force sensors are better than traditional rod force sensors in terms of required measurement accuracy, dynamic response, anti-electromagnetic interference, stability and reliability of zero output of sensors in the full temperature and air pressure range. Resistance strain sensors are much higher.

However, in the field of FBG sensing, strain and temperature are two physical quantities that can directly cause the center wavelength of FBG to drift, that is, FBG is cross-sensitive to temperature and strain. Since fiber gratings are sensitive to both temperature and strain, it is difficult to eliminate the influence of temperature when measuring strain, which limits its practical application.

Contents of the invention

technical problem to be solved

In order to avoid the deficiencies of the prior art, the present invention proposes a temperature self-compensating fiber grating rod force sensor, which can eliminate the influence of temperature while measuring the strain, has a simple manufacturing process, and solves the problem of cross-sensitivity of the fiber grating sensor .

Technical solutions

A temperature self-compensating fiber grating rod force sensor, characterized in that it includes a first associated parallel beam 2, a second associated parallel beam 3, a first optical fiber grating strain sensor 4 and a second optical fiber grating strain sensor 5: the first associated parallel beam 2 and the second associated parallel beam 3 are rectangular frame structures with the same size, and the center is a rectangular hollow; the rectangular hollow rectangular frames of the two associated parallel beams go forward and are vertically fixedly connected to each other, and the first fiber grating strain sensor 4 and the rectangular hollow The rectangular frame is pasted on a plane of the first associated parallel beam 2 in parallel, the second fiber grating strain sensor 5 is pasted on a plane of the second associated parallel beam 3 in parallel with the rectangular hollow rectangular frame, and the first fiber grating strain sensor The sensor 4 is connected in series with the second fiber grating strain sensor 5; the position of the first fiber grating strain sensor 4 on the plane of the first associated parallel beam 2 is vertically symmetrical to the position of the second fiber grating strain sensor 5 on the plane of the second associated parallel beam 3 .

The material and structure of the first FBG strain sensor 4 and the second FBG strain sensor 5 are the same, and the difference in central wavelength is less than 50nm.

Paste several FBG strain sensors in series with the first FBG strain sensor 4 on the plane of the first associated parallel beam 2, and paste several FBG strain sensors connected in series with the second FBG strain sensor 5 on the plane of the second associated parallel beam 3 Fiber Bragg grating strain sensor, and the positions pasted on the two planes are vertically symmetrical.

The several optical fiber grating strain sensors are multiples of 2.

The fiber grating strain sensor is a patch fiber grating sensor or a bare fiber grating sensor.

The fiber grating is a fiber Bragg grating or a long period fiber grating.

Beneficial effect

The temperature self-compensating fiber grating rod force sensor proposed by the present invention solves the problem of temperature compensation inside the sensor system without introducing additional additional structures or special fiber grating temperature sensors; and the temperature self-compensating fiber grating rod force sensor The sensor has the characteristics of anti-electromagnetic interference, high precision, fast dynamic response, small size, light weight, simple structure, etc., and is more reliable, stable and simple; in addition, the temperature self-compensating fiber grating rod force sensor is relatively cheap In a relatively narrow space, the temperature compensation of the sensor can be realized while measuring the force of the elastic element.

Description of drawings

Figure 1: Schematic diagram of the structure of the temperature self-compensating fiber grating rod force sensor in Embodiment 1 of the present invention

Figure 2: Schematic diagram of the structure of the temperature self-compensating fiber grating rod force sensor in Embodiment 2 of the present invention

Figure 3: Schematic diagram of the structure of the temperature self-compensating fiber grating rod force sensor in Embodiment 3 of the present invention

1-elastic element; 2-the first associated parallel beam; 3-the second associated parallel beam; 4-the first optical fiber grating strain sensor; 5-the second optical fiber grating strain sensor;

Detailed ways

Now in conjunction with embodiment, accompanying drawing, the present invention will be further described:

Accompanying drawing 1 is a kind of temperature self-compensating fiber grating rod force sensor of the embodiment 1 of the present invention, which includes the elastic element 1 that is made up of the first associated parallel beam 2 and the second associated parallel beam 3, the first fiber grating strain sensor 4 and the second fiber grating strain sensor 5; the first fiber grating strain sensor 4 and the second fiber grating strain sensor 5 are respectively pasted on two faces 2-1, 2-2 of the associated parallel beam 2 and two sides of the associated parallel beam 3 In the axial direction of the surfaces 3-1 and 3-2, the first FBG strain sensor 4 and the second FBG strain sensor 5 are sequentially connected on the same optical fiber. The first FBG strain sensor 4 senses the strain generated by the z-direction force, and the second FBG strain sensor 5 senses the strain generated by the y-direction force, wherein the y and z directions are perpendicular to each other.

Wherein the first fiber Bragg grating strain sensor 4 and the second fiber Bragg grating strain sensor 5 are patch type fiber Bragg grating strain sensors, and the first fiber Bragg grating strain sensor 4 and the second fiber Bragg grating strain sensor 5 are all pasted on the central axis of the surface on the side. A z-direction force is applied to the above fiber grating rod force sensor, while a constant temperature is also applied to the fiber grating rod force sensor.

Embodiment 2: Referring to accompanying drawing 2, the difference from Embodiment 1 is that the first FBG strain sensor 4 and the second FBG strain sensor 5 are bare fiber Bragg gratings, and the first FBG strain sensor 4 It consists of two bare fiber Bragg gratings 4-1, 4-2 connected in sequence and pasted on the central axis of the surface. The second fiber Bragg grating strain sensor 5 consists of two bare fiber Bragg gratings 5-1, 5-2 in sequence. The secondary connection is formed and pasted on the central axis of the surface where it is located. When the rod force sensor is bent and deformed, the center wavelength drift of the first fiber Bragg grating strain sensor 4 takes the average value of the center wavelength drift of the bare fiber Bragg grating 4-1, 4-2; the center wavelength of the second fiber Bragg grating strain sensor 5 The drift is the average value of the center wavelength drift of the bare fiber Bragg gratings 5-1 and 5-2.

Embodiment 3: Referring to accompanying drawing 3, the difference from Embodiment 1 is that the first FBG strain sensor 4 and the second FBG strain sensor 5 are bare long-period fiber gratings, and the first FBG strain sensor 4 is composed of four bare long-period fiber gratings 4-1, 4-2, 4-3, 4-4 connected in sequence and pasted on the surface, arranged in two rows up and down, and parallel to the upper and lower sides of the surface. The second fiber grating strain sensor 5 is composed of two bare long-period fiber gratings 5-1, 5-2, 5-3, 5-4 sequentially connected and pasted on the central axis of the surface. When the rod force sensor is bent and deformed, the center wavelength drift of the first fiber Bragg grating strain sensor 4 is the average value of the center wavelength drift of the bare fiber Bragg grating 4-1, 4-2, 4-3, 4-4; The central wavelength drift of the fiber Bragg grating strain sensor 5 is the average value of the central wavelength drift of the bare fiber Bragg gratings 5-1, 5-2, 5-3, and 5-4.

Claims (6)

1. temperature self-compensation fiber grating stick force sensor, it is characterized in that comprising the first related parallel girder (2), the second related parallel girder (3), first fiber Bragg grating strain sensor (4) and second fiber Bragg grating strain sensor (5): the first related parallel girder with second of related parallel girder (2) (3) is measure-alike rectangle frame structure, and the center is rectangle hollow; The rectangle hollow rectangle frame direct motion of two related parallel girders and vertical fixing connection mutually, on first fiber Bragg grating strain sensor (4) and the parallel plane that sticks on the first related parallel girder (2) of rectangle hollow rectangle frame, on second fiber Bragg grating strain sensor (5) and the parallel plane that sticks on the second related parallel girder (3) of rectangle hollow rectangle frame, and first fiber Bragg grating strain sensor (4) and second fiber Bragg grating strain sensor (5) series connection; First fiber Bragg grating strain sensor (4) at the position on first related parallel girder (2) plane and second fiber Bragg grating strain sensor (5) in second related parallel girder (3) the planimetric position vertical symmetry.

2. temperature self-compensation fiber grating stick force sensor according to claim 1, it is characterized in that: described first fiber Bragg grating strain sensor (4) is identical with structure with the material of second fiber Bragg grating strain sensor (5), and centre wavelength differs less than 50nm.

3. temperature self-compensation fiber grating stick force sensor according to claim 1 and 2, it is characterized in that: several fiber Bragg grating strain sensors of connecting with first fiber Bragg grating strain sensor (4) are pasted on the plane at the first related parallel girder (2), simultaneously paste several fiber Bragg grating strain sensors of connecting with second fiber Bragg grating strain sensor (5) on the plane of the second related parallel girder (3), and the position vertical symmetry of pasting on two planes.

4. temperature self-compensation fiber grating stick force sensor according to claim 3 is characterized in that: described several fiber Bragg grating strain sensors are 2 multiple.

5. temperature self-compensation fiber grating stick force sensor according to claim 1 is characterized in that: described fiber Bragg grating strain sensor is SMD fiber-optic grating sensor or bare optical fibers and bare optical gratings sensor.

6. temperature self-compensation fiber grating stick force sensor according to claim 5 is characterized in that: described fiber grating is Fiber Bragg Grating FBG or long period fiber grating.

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