CN105823440A - Optical fiber angular displacement sensor based on differential light intensity principle and measurement method - Google Patents

Abstract

The invention provides an optical fiber angular displacement sensor based on a differential light intensity principle and a measurement method. The angular displacement sensor comprises two receiving optical fiber bundles, an emergent optical fiber bundle and a support, wherein the top surface of the support is a curved surface, and the middle position is provided with a through hole; two symmetrical sliding grooves are arranged at two sides of the through hole; the two receiving optical fiber bundles are respectively fixed in the sliding grooves; the included angle alpha between the receiving optical fiber bundle and the emergent optical fiber bundle is an acute angle; the lower end part of the emergent optical fiber bundle is fixed in the through hole to form a probe; and the upper end of the emergent optical fiber bundle is connected with a power supply.

Description

Optical Fiber Angular Displacement Sensor based on differential light intensity principle and measuring method

Technical field

The present invention relates to a kind of Fibre Optical Sensor, particularly relate to a kind of differential light intensity Optical Fiber Angular Displacement Sensor measuring angle.

Background technology

Along with the development of engineering machinery, reliability and fault diagnosis to engineering machinery there has also been higher requirement.Axle system is the vitals of mechanized equipment, be especially used in large-scale engineering machinery, Generator Set, shipping industry medium in power transmission shaft

Having particularly important effect, for preventing the serious twisting vibration of axle system from may cause the harm that axle system crackle and fracture bring, shaft torsional oscillation is monitored in real time has become engineering machinery development problem demanding prompt solution.

Measure at present the method for shafting torsional oscillation and mainly have two big classes: contact measurement and non-cpntact measurement, the former is by sensor (foil gauge, accelerometer etc.) it is mounted on an axle, the signal measuring gained passes to instrument through the mode of collecting ring or radio sender.Contact measuring method is typically necessary devices such as installing some sensors on axle, therefore sometimes has to destroy the structure that power transmission shaft is original, and these are not allowed in many cases, and now noncontact measuring method just shows its superiority.

Using eyes with non-contact method to measure shafting torsional oscillation, a lot of scientific research personnel has done relevant research work.The measuring instrument measuring torsional oscillation the earliest is Geiger digital torsional vibration instrument, and the method is simple and practical, but because the torsional oscillation of axle is delivered to measure the headstock by belt, the elastic vibration of belt can cause distortion, can not measure the torsional oscillation that frequency is the lowest.Research in addition with relatively advanced non-contact measurement, such as motor shafting torsional vibration test based on high-speed CCD photography technology, torsional vibration measurement based on laser doppler technique etc., but due to certainty of measurement have much room for improvement, the problem such as expensive, installation difficulty and cause and cannot extensively apply.

Since the Fibre Optical Sensor appearance seventies in last century, the Fibre Optical Sensor development of more than 30 year, work out various types of Fibre Optical Sensor, it has many advantages: (1) is not by electromagnetic interference, corrosion-resistant；(2) volume is little, light weight, flexible；(3) dependable performance, highly sensitive, service life is long.Wherein principle is simple, flexible design surely belong to Reflective Intensity-modulatedFiber-optic Sensor, apply the most extensive.Design this sensor and use differential light intensity principle to be applied to measure the research of shafting torsional oscillation at home seldom.The technical data being available for referring to the most suddenly lacks.

Summary of the invention

The present invention is to solve drawbacks described above and deficiency present in prior art, it is provided that a kind of Optical Fiber Angular Displacement Sensor based on differential light intensity principle and measuring method, this sensor construction is simple, use cost is low, stable performance, certainty of measurement are higher.

For solving above-mentioned technical problem, the present invention provides a kind of Optical Fiber Angular Displacement Sensor based on differential light intensity principle, including 2 root receiving fiber bundles, 1 outgoing fibre bundle and support；Described cradle top surface is curved surface, and centre position is provided with through hole；The both sides of described through hole are provided with 2 chutes of symmetry；2 described reception fibre bundles are separately fixed in described chute, and the angle α between described reception fibre bundle and described outgoing fibre bundle is acute angle, the bottom of described outgoing fibre bundle forms probe in being fixed on described through hole, and the upper end of described outgoing fibre bundle is connected with power supply.

Further, the angle α between described reception fibre bundle and described outgoing fibre bundle, 0 ＜ α≤45 °.

Further, described reception fibre bundle is fixed in described chute by trip bolt.

Further, described reception fibre bundle includes the 1 reception optical fiber as axle center, the inner ring around axle center receives optical fiber and outer ring receives optical fiber.

Further, it is 6 that described inner ring receives optical fiber, and it is 12 that described outer ring receives optical fiber.

Further, described outgoing fibre bundle includes that the 1 outgoing optical fiber as axle center, the inner ring around axle center receive optical fiber and outer ring receives optical fiber.

Further, it is 6 that described inner ring receives optical fiber, and it is 12 that described outer ring receives optical fiber.

The measuring method of Optical Fiber Angular Displacement Sensor based on differential light intensity principle, comprises the following steps:

Step one, is positioned over the underface of described sensor by measured object, distance h between measuring probe and measured object, and calculates fiber end face virtual image distance Z to outgoing fibre bundle of 2 root receiving fiber bundles respectively₁And Z₂；

Step 2, calculates 2 root receiving fiber bundles respectively, the reception fiber strength I of the rightest reception fibre bundle and left reception fibre bundle_right、I_left, computing formula is as follows:

Wherein, r₁And r₂Being respectively the effective radius receiving light area of right reception fibre bundle, left reception fibre bundle, K is correction factor, K₀For light wave loss in outgoing fibre bundle, I₀For the intensity in light source couples to outgoing fibre bundle；S₁And S₂Reception fibre bundle the rightest, left receives light area, and ω (z) is optical field distribution equivalent redius, exp (-η₁r₁) and exp (-η₂r₂) reception fibre bundle fiber kinks the rightest, left produce light intensity added losses,For position in fibre bundle end face light field, (r, z) pharosage at place, ρ is the coefficient of light reflection in a fiber, η₁And η₂Fibre bundle intensity modulation coefficient the rightest, left；

Step 3, utilizes optical-electrical converter to receiving fiber strength I_right、I_leftCarry out multiple amplification, obtain the right side, the output voltage U of left reception fibre bundle_right、U_left, specific formula for calculation is as follows:

Wherein, k_υFor receiving the amplification of fiber strength.

The Advantageous Effects that the present invention is reached: a kind of based on differential light intensity principle the Optical Fiber Angular Displacement Sensor of present invention offer and measuring method, different α and h values can be selected according to practical measurement requirement, it is used for regulating maximum sensitivity, can effectively accept differential light intensity signal, there is simple in construction, low cost, certainty of measurement high simultaneously, be more suitable for non-contact measurement angular displacement and the most protected from environmental.

Accompanying drawing explanation

The angular displacement sensor structure schematic diagram of Fig. 1 present invention；

The supporting structure schematic diagram of Fig. 2 present invention；

The angular displacement sensor intensity modulation geometrical relationship principle schematic of Fig. 3 present invention；

The normalization performance diagram of Fig. 4 present invention.

Detailed description of the invention

The invention will be further described below in conjunction with the accompanying drawings.Following example are only used for clearly illustrating technical scheme, and can not limit the scope of the invention with this.

As shown in Figure 1-2, the present invention provides a kind of Optical Fiber Angular Displacement Sensor based on differential light intensity principle, including 2 root receiving fiber bundle 1,2,1 outgoing fibre bundle 3 and support 4；Described support 4 end face is curved surface, and centre position is provided with through hole 8；The both sides of described through hole 8 are provided with 2 chutes 6,7 of symmetry；2 described reception fibre bundles 1,2 are separately fixed at described chute 6, in 7, and described reception fibre bundle 1, angle α between 2 and described outgoing fibre bundle 3 is acute angle, and the bottom of described outgoing fibre bundle 3 forms probe in being fixed on described through hole 8, and the upper end of described outgoing fibre bundle 3 is connected with power supply.Angle α between described reception fibre bundle 1,2 and described outgoing fibre bundle 3,0 ＜ α≤45 °.Described reception fibre bundle 1,2 is fixed in described chute 6,7 by trip bolt 5.

Described reception fibre bundle 1,2 includes the 1 reception optical fiber as axle center, the inner ring around axle center receives optical fiber and outer ring receives optical fiber.It is 6 that described inner ring receives optical fiber, and it is 12 that described outer ring receives optical fiber.

Described outgoing fibre bundle 3 includes that the 1 outgoing optical fiber 31 as axle center, the inner ring around axle center receive optical fiber 32 and outer ring receives optical fiber 33.It is 6 that described inner ring receives optical fiber 32, and it is 12 that described outer ring receives optical fiber 33.

The measuring method of Optical Fiber Angular Displacement Sensor based on differential light intensity principle, comprises the following steps:

Step one, is positioned over the underface of described sensor by measured object, distance h between measuring probe and measured object, and calculates fiber end face virtual image distance Z to outgoing fibre bundle of 2 root receiving fiber bundles respectively₁And Z₂, as shown in Figure 3, i.e. reflecting surface inclines and incident optical Shu Guang has geometrical relationship during angle, wherein γ is by the angular displacement of side, d is right, the radius of left reception fibre bundle, C is outgoing fibre bundle and the midpoint of measured surface outgoing fibre bundle virtual image end face time vertical, the midpoint of outgoing fibre bundle virtual image when C ' is measured surface generation γ angular displacement, E, B is respectively the right side, the midpoint of left reception fibre bundle end face, A is the midpoint of outgoing fibre bundle end face, P is right, distance between left reception fibre bundle end face and outgoing fibre bundle end face, F, D is respectively EB and AC ', the intersection point of AC, specific formula for calculation is:

Wherein,Wherein, d ' is right to accept fibre bundle effective light-receiving diameter；D " it is left to accept fibre bundle effective light-receiving diameter；S₁Fibre bundle effective light-receiving light area is accepted for right；S₂Fibre bundle effective light-receiving light area is accepted for left；

Step 2, calculates 2 root receiving fiber bundles respectively, the reception fiber strength I of the rightest reception fibre bundle and left reception fibre bundle_right、I_left, computing formula is as follows:

Wherein, r₁And r₂Being respectively the effective radius receiving light area of right reception fibre bundle, left reception fibre bundle, K is correction factor, K₀For light wave loss in outgoing fibre bundle, I₀For the intensity in light source couples to outgoing fibre bundle；S₁And S₂Reception fibre bundle the rightest, left receives light area, and ω (z) is optical field distribution equivalent redius, exp (-η₁r₁) and exp (-η₂r₂) reception fibre bundle fiber kinks the rightest, left produce light intensity added losses,For position in fibre bundle end face light field, (r, z) pharosage at place, ρ is the coefficient of light reflection in a fiber, η₁And η₂Fibre bundle intensity modulation coefficient the rightest, left；

Step 3, utilizes optical-electrical converter to receiving fiber strength I_right、I_leftCarry out multiple amplification, obtain the right side, the output voltage U of left reception fibre bundle_right、U_left, specific formula for calculation is as follows:

Wherein, k_υFor receiving the amplification of fiber strength.

In order to the technique effect of the present invention is described, employing emulation experiment illustrates, and emulation experiment is set P=100 μm, h=500mum to sensor parameters, angular displacement changes in the range of ± 20 °, the reception fiber strength I to right reception fibre bundle and left reception fibre bundle_right、I_leftCarry out processing under normalizing obtaining normalization characteristic curve, as shown in Figure 4, it can be seen that the reception fiber strength I of reception fibre bundle right, left_right、I_leftThe higher linearity is presented with the change of angular displacement.

The above is only the preferred embodiment of the present invention; it should be pointed out that, for those skilled in the art, on the premise of without departing from the technology of the present invention principle; can also make some improvement and deformation, these improve and deformation also should be regarded as protection scope of the present invention.

Claims (8)

1. an Optical Fiber Angular Displacement Sensor based on differential light intensity principle, it is characterised in that: include 2 root receiving fiber bundles, 1 outgoing fibre bundle and support；Described cradle top surface is curved surface, and centre position is provided with through hole；The both sides of described through hole are provided with 2 chutes of symmetry；2 described reception fibre bundles are separately fixed in described chute, and the angle α between described reception fibre bundle and described outgoing fibre bundle is acute angle, the bottom of described outgoing fibre bundle forms probe in being fixed on described through hole, and the upper end of described outgoing fibre bundle is connected with power supply.

Optical Fiber Angular Displacement Sensor based on differential light intensity principle the most according to claim 1, it is characterised in that: the angle α between described reception fibre bundle and described outgoing fibre bundle, 0 ＜ α≤45 °.

Optical Fiber Angular Displacement Sensor based on differential light intensity principle the most according to claim 1, it is characterised in that: described reception fibre bundle is fixed in described chute by trip bolt.

Optical Fiber Angular Displacement Sensor based on differential light intensity principle the most according to claim 1, it is characterised in that: described reception fibre bundle includes the 1 reception optical fiber as axle center, the inner ring around axle center receives optical fiber and outer ring receives optical fiber.

Optical Fiber Angular Displacement Sensor based on differential light intensity principle the most according to claim 4, it is characterised in that: it is 6 that described inner ring receives optical fiber, and it is 12 that described outer ring receives optical fiber.

Optical Fiber Angular Displacement Sensor based on differential light intensity principle the most according to claim 1, it is characterised in that: described outgoing fibre bundle includes that the 1 outgoing optical fiber as axle center, the inner ring around axle center receive optical fiber and outer ring receives optical fiber.

Optical Fiber Angular Displacement Sensor based on differential light intensity principle the most according to claim 6, it is characterised in that: it is 6 that described inner ring receives optical fiber, and it is 12 that described outer ring receives optical fiber.

8. according to the measuring method of the Optical Fiber Angular Displacement Sensor based on differential light intensity principle described in any one of claim 1-7, it is characterised in that comprise the following steps:

Step one, is positioned over the underface of described sensor by measured object, distance h between measuring probe and measured object, and calculates fiber end face virtual image distance Z to outgoing fibre bundle of 2 root receiving fiber bundles respectively₁And Z₂；

Step 2, calculates 2 root receiving fiber bundles respectively, the reception fiber strength I of the rightest reception fibre bundle and left reception fibre bundle_right、I_left, computing formula is as follows:

$I_{right}=\frac{{\mathrm{\ρKK}}_0{I}_0{S}_1}{{\mathrm{\π\ω}}^2\left(z_1\right)}\·\exp \[-\frac{{r_1}^2}{{\mathrm{\ω}}^2\left(z_1\right)}\]\·\exp (-{\mathrm{\η}}_1{r}_1)$

$I_{left}=\frac{{\mathrm{\ρKK}}_0{I}_0{S}_2}{{\mathrm{\π\ω}}^2\left(z_2\right)}\·\exp \[-\frac{{r_2}^2}{{\mathrm{\ω}}^2\left(z_2\right)}\]\·\exp (-{\mathrm{\η}}_2{r}_2)$

Wherein, r₁And r₂Being respectively the effective radius receiving light area of right reception fibre bundle, left reception fibre bundle, K is correction factor, K₀For light wave loss in outgoing fibre bundle, I₀For the intensity in light source couples to outgoing fibre bundle；S₁And S₂Reception fibre bundle the rightest, left receives light area, and ω (z) is optical field distribution equivalent redius, exp (-η₁r₁) and exp (-η₂r₂) reception fibre bundle fiber kinks the rightest, left produce light intensity added losses,For position in fibre bundle end face light field, (r, z) pharosage at place, ρ is the coefficient of light reflection in a fiber；η₁And η₂Fibre bundle intensity modulation coefficient the rightest, left；

Step 3, utilizes optical-electrical converter to receiving fiber strength I_right、I_leftCarry out multiple amplification, obtain the right side, the output voltage U of left reception fibre bundle_right、U_left, specific formula for calculation is as follows:

$\begin{array}{c}{U}_{right}=k_v{I}_{right}\\ =\frac{k_v{\mathrm{\ρKK}}_0{I}_0{S}_1}{{\mathrm{\π\ω}}^2\left(z_1\right)}\·\exp \[-\frac{{r_1}^2}{{\mathrm{\ω}}^2\left(z_1\right)}\]\·\exp (-{\mathrm{\η}}_1{r}_1)\end{array}$

$\begin{array}{c}{U}_{left}=k_v{I}_{left}\\ =\frac{k_v{\mathrm{\ρKK}}_0{I}_0{S}_2}{{\mathrm{\π\ω}}^2\left(z_2\right)}\·\exp \[-\frac{{r_2}^2}{{\mathrm{\ω}}^2\left(z_2\right)}\]\·\exp (-{\mathrm{\η}}_2{r}_2)\end{array}$

Wherein, k_υFor receiving the amplification of fiber strength.