RU2146373C1 - Fiber-optical acceleration transducer - Google Patents

Abstract

FIELD: measurement technology. SUBSTANCE: given acceleration transducer is intended for use in high- precision measurement with the aid of optical sensors matched with light guides including fiber-optical sensors which sensitive elements are based on fiber light guides. This acceleration transducer can be used as base to design three-coordinate precision digital fiber-optical accelerometer for measurement of linear accelerations, very low accelerations included, within wide dynamic range. Case of transducer houses reflector. End of fiber light guide is supported as cantilever in case. Inertial mass is anchored on free end of cantilever of fiber light guide placed in through hole in inertial mass. End face of free end of cantilever of fiber light guide is located above reflector. Inductance coils are positioned in case in symmetry with axis of fiber light guide. Reflector is manufactured in the form of concave mirror formed by two cylindrical surfaces. Axes of cylindrical surfaces are mutually perpendicular and cross axis of fiber light guide at right angles above cut of concave mirror. Center of mass of inertial mass made from magnetic material lies on axis of fiber light guide. EFFECT: increased precision of measurement of linear accelerations. 4 dwg

Description

 The invention relates to measuring technique, in particular to the technique of high-precision measurements by means of optical sensors (OD), interfaced with fiber optical fibers (AF), including fiber-optic (VOD), sensitive elements of which are made on the basis of the aircraft.

 By the method of presenting output data, digital (pulsed) and analog ODs (AOD) are known. The first, when changing the measured quantities acting on them, discretely (impulse) change the level of the output signal; the second - in accordance with changes in the measured values continuously (analogously) modulate any parameter (intensity, frequency, phase or angle of rotation of the plane of polarization) of the optical radiation flux passing through them. Structurally and in operation, analogue VODs are much simpler.

 Known AOD acceleration [1], comprising a housing with a cantilever elastic plate fixed in it, at the free end of which an inertial mass (MI) is fixed, the end surface of which is perpendicular to the plane of the plate is made mirror. Opposite the mirror surface are the ends of the three lying in the same plane ends of the fiber optical fibers (AF), rigidly fixed in the housing so that their axes lie in a plane perpendicular to the plane of the elastic plate. The optical layout of the AOD is aligned so that, in the absence of acceleration of an object carrying an AOD, the light coming from the end of the middle aircraft, after reflection from the mirror, is evenly distributed between the ends of adjacent adjacent aircraft. The appearance of acceleration, whose vector (or its component) is perpendicular to the plane of the elastic plate, leads to a displacement of the MI and, thereby, to a change in the fraction of the radiation flux entering the ends of the receiving aircraft. The differential mismatch circuit generates a difference signal proportional to the magnitude of the acceleration acting on the AOD.

 The disadvantages of such an AOD can be considered its "single-coordinate" and low threshold sensitivity, determined by the rigidity of the plate and the magnitude of the IM.

 A higher threshold sensitivity and two sensitivity axes are possessed by acceleration AOD [2], which we took as a prototype. The prototype AOD-prototype contains a housing with the end of the segment of the aircraft fixed to it in a cantilever manner, on the free end of the console of which is dressed with its through hole and mounted on it so that the radiation flux freely leaves the end of the aircraft, opposite which there is a mirror reflector fixed in the body. When acceleration is applied to the AOD, the vector of which (or its component) is perpendicular to the axis of the aircraft, a part of the radiation flux, depending on the magnitude of the acceleration, is returned back to the aircraft and, using a Y-shaped fiber-optic splitter-adder, is fed to an optoelectronic analyzing unit.

The main disadvantage of the AOD prototype, like any other AOD coupled to the aircraft, is the low accuracy of measurements made with their help. The real value of the maximum achievable minimum relative measurement error for them is 10 ^-1 -10 ^-2 % [3].

 The objective of the present invention is to develop a pulsed VOD, combining the simplicity of design inherent in AOD, with the ability to conduct high-precision measurements inherent in digital OD. Such a VOD can serve as the basis for the construction of a three-coordinate precision digital fiber-optic accelerometer for measuring linear accelerations, including ultra-small, in a wide dynamic range.

 The problem is solved in that in the water containing a housing with a reflector fixed in it, a fiber light guide, part of which is cantilevered in the housing, an inertial mass mounted on the free end of the aircraft console located in the through hole made in the MI, and the end of the free end of the console The aircraft is located above the reflector, induction coils are introduced, installed in the housing symmetrically to the axis of the aircraft console, the reflector is made in the form of a concave mirror formed by two cylindrical surfaces, limited E plane. In this case, the axes of the cylindrical surfaces are mutually perpendicular, lie in the same plane and intersect with the axis of the aircraft at right angles above the bounding plane, and the center of mass of the MI made of soft magnetic material lies on the axis of the aircraft.

 To increase the accuracy of measurements (in the case of use, a multimode aircraft), a modulating raster of alternating transparent and opaque concentric circular stripes can be located in the plane of the end face of the aircraft console. Moreover, the central transparent circle of the raster has a diameter of 0.1d (d is the diameter of the light guide core of the aircraft), and the remaining circles of the raster have a width of circular stripes of 0.15d, and the center of the circular rasters coincides with the center of the end of the aircraft. The raster can be made either directly at the end of the aircraft, or on a transparent base with its subsequent fastening at the end of the aircraft. When using a single-mode aircraft, a modulating raster is not needed.

 Comparative analysis with the prototype and with other similar technical solutions allows us to conclude that the proposed technical solution is not part of the prior art, i.e. meets the criterion of "novelty."

 An analysis of the features of the proposed technical solution and comparison with the prior art in this field, as well as in other areas, shows that the newly introduced features do not follow explicitly from the prior art, thus, the proposed technical solution has an inventive step.

 The main disadvantage of the AOD prototype (the fundamentally low accuracy of measurements implemented with its help) is due to the metrologically low quality of the optical radiation stream passing through it, which plays the role of both a carrier and an information recipient in the AOD - a large level of its own noise at a low general level of intensity. Moreover, a simple increase in the power of the optical flow in the measuring path of the AOD cannot radically improve the situation. Firstly, together with an increase in the power of the optical radiation flux in proportion to the square root of its value, the power of the intrinsic (photonic or, as they are called, shot) noise of the flux also grows, i.e. A 1000-fold increase in optical power in the measuring path of the AOD can ultimately give only a 30-fold increase in the accuracy of measurements. Secondly, the introduction of large power levels into the aircraft (≈ 1 W for standard multimode quartz-quartz aircraft with a light guide core diameter of 50 μm) causes nonlinear effects in them that violate the principle of analog measurements, which underlies the operation of AOD. All of the above fully applies to any type of AOD (modulating the intensity, phase, frequency or angle of rotation of the plane of polarization of the radiation flux passing through them), since the modulation of any of the listed parameters of optical radiation carried out by them should ultimately (before applying to the phase transition) transformed into intensity modulation, the integral changes of which can only be perceived by all existing AFs.

 Analyzing the foregoing, we conclude that in order to increase the accuracy of measurements, it is necessary to revise the ideology of both the principles of forming the informative signal in the mates that are interfaced with the aircraft, and the principle of its subsequent electrical processing, and switch from analog to digital (pulse, counting) measurement principles. It is necessary to abandon the analog modulation of the optical parameters of the radiation flux and proceed to non-analog (discrete) modulation, thereby introducing new, non-optical parameters into the radiation flux that will act as information recipients. This will preserve all the advantages of VO (the carrier of information, as before, remains the stream of optical radiation), however, the problem of measurement accuracy will no longer be associated with the problem of measuring the intensity of a low-power stream of optical radiation - it is transferred from the field of optical measurements to other, non-optical, where these problems are either not in principle, or they are solved at the proper level.

 In the general case of non-analog modulation of the radiation flux, information can be superimposed either on its discrete-spatial (coordinate) distribution, or on the discrete-time (pulsed) one.

 In the first case, the information is encoded by the spatial arrangement of the optical (streams) signals emerging from the OD.

In the second case, the information parameter of the pulse sequence can be:
- the number of pulses itself (the measurement process in this case can be reduced simply to an account, which, in principle, can be produced accurately);
- pulse repetition rate (the measurement process can be reduced to counting the number of pulses per unit time: the measurement of time intervals can be performed with proper accuracy);
- time intervals between pulses (the measurement process can be reduced to determining the time intervals between pulses with their subsequent processing according to the adopted algorithm for this particular case), etc.

 The aforesaid involves either the creation of special, non-analog, ODs, or, which is sometimes possible, the use of certain types of analog ODs in non-analogous modes that are unusual for them, as a result of which optical signals are generated at their outputs with periodic modulation of one or another optical radiation parameter, which, with appropriate detection, can be converted into pulsed electrical signals.

 An example of the practical implementation of OD of the first type are the raster data centers considered above. The measurement accuracy in this case is determined by the accuracy of the manufacturing of modulating rasters and, in principle, can be arbitrarily high. The obvious advantage of the data center is the simplicity of obtaining the measurement result: the disadvantages are the large dimensions of the modulating rasters, which are greater the higher the required measurement accuracy: a small circle of values that can be measured by such ODs (almost only angular and linear displacements).

 Much broader functionality is possessed by ODs, which form the output signal in the form of a time sequence of optical pulses. The use of special modulators in such ODs with cyclic interrupters of the radiation flux that are sensitive to physical quantities acting on ODs allows one to create ODs for measuring various physical quantities (mechanical, electrical, magnetic, thermal, etc.).

 Obviously, the formation of pulsed, non-analog, optical signals in all the above ODs and the pulsed, non-analog, perception of them by subsequent processing schemes makes such measuring systems insensitive to any kind of instability of the parameters of the elements forming the optical measuring path (AI, VS, FP, etc.).

 Digital OD signals are processed by digital methods and means, which virtually eliminates the possibility of errors in processing devices, and in the case of microprocessor processing, it allows targeted correction of OD signals to neutralize the effect of natural defects and imperfections of the OD on the result of measurements made using them. This allows the main burden of the intellectual load in the measurement process to be transferred from the OD to the signal processing devices, i.e., having such a powerful signal processing apparatus, it is possible to reduce the level of requirements imposed on the OD itself, without reducing the quality requirements of measurements in general . In this case, the requirements for OD can be mitigated: they can be simpler constructively and in production, they can be reduced operational requirements, etc.

 Theoretically, the error of the IC with time-pulse OD is limited by the possible accuracy of the formation of time intervals between optical pulses and the subsequent accuracy of their measurement.

 Thus, the set of essential features of the proposed technical solution allows us to solve the problem of the accuracy of measurements made by means of conjugated with aircraft OD. This is achieved due to the rejection of analog modulation and the transition from fundamentally low-current measurements of the intensity of a low-power optical radiation flux to temporary measurements, which can be performed with the required high accuracy.

 In FIG. 1 shows the design of the inventive water. In FIG. 2 shows a view of the end face of the aircraft with a modulating raster mounted on it. In FIG. 3 shows a functional diagram of a possible version of the accelerometer based on the proposed water. In FIG. 4 is a timing chart explaining the operation of the water.

 The inventive water (see figure 1) contains a housing 1 with a console end fixed to it BC 2. At the free end of BC 2 is fixed IM 3 made of soft magnetic material in the form of a cylinder with an axial hole, which it is worn on the end of BC 2 and usually fixed so that the plane of the end face of BC 2 coincides with the plane of the base of the cylinder IM 3. On this base, a raster 4 of alternating transparent and opaque concentric circular bands can be located (see Fig. 2). Opposite the end of BC 2, a concave mirror 5 is rigidly fixed to it, made in the form of two cylindrical surfaces, the mutually perpendicular axis of curvature of which intersects the axis of BC 2 at right angles above the cut plane of mirror 5. At the same time, the free end of the BC 2 console is fixed in the through hole 3 so that its center of mass lies on the axis of the aircraft 2, symmetrically to which inductors 6 are fixed in the housing 1.

 Modulating raster 4 (see Fig. 2) can be used if the BC 2 console (see Fig. 1) is made of a multimode aircraft with a relatively thick light guide core, which leads to the formation of wide optical pulses at the output of the VOD and reduces the accuracy of the start -stop circuit electronic processing unit, and ultimately the accuracy of the measurements as a whole. In this case, it is possible to increase the accuracy of the start-stop circuit by reducing the width of the optical pulses generated by the VOD, for which raster 4 serves.

 The body of the VOD 1 can be made of non-magnetic material with a low coefficient of thermal expansion, which provides rigid fixation of the structural elements of the VOD attached to it, for example, Invar.

 As aircraft 2, a standard single- or multi-mode aircraft of the quartz-quartz type with a polyacrylate protective and hardening coating can be used.

 As the material of the magnetic mass 3 can be used, for example, electrical steel.

 Modulating raster 4 can be performed, for example, by photo- (electronically) lithography on a metal film, for example chromium, deposited by thermal evaporation either directly on the end of the aircraft, or on a thin transparent base, for example glass, which is then fixed on the end of the aircraft.

 The concave mirror 5 can be made either glass with subsequent metallization (silver or aluminum) of the reflecting surface, or directly in the material of the body of the water, also with its subsequent coating with metal with a high reflection coefficient. The radius of curvature of the mirror surface can be from one to several millimeters.

 Inductors 6 can be performed by a conventional winding wire on a non-magnetic frame, for example, a cylindrical shape.

 The design of the VOD assumes its operation in regimes with different dynamic ranges of perception of the magnitude of the measured acceleration, which is reflected in various values of the radii of rotation of the BC 2 console, like a spherical pendulum, during the operation of the VOD. In accordance with this, in each particular case, it is necessary to set the length of the BC 2 cantilever (see Fig. 1) such that the condition for optical alignment of the BC 2 end face relative to the axis of curvature of the mirror 5 is met for this case. In this case, the distance between the end face of the free end of the BC 2 console and the mirror 5 is set so that the circular motion of the center of the end face of the free end of the console BC 2 during operation of the VOD in the absence of acceleration is carried out in the plane of the axis of curvature of the mirror 5.

 When adjusting, the relative position of the center of mass of the IM 3 and the inductance coils 6 is also established. In this case, the inductors 6 are positioned so that their axis of symmetry parallel to the axis of curvature of the mirror 5 forms a square along which the center of mass of the IM 3 moves along the circle the work of water.

 The operation of the proposed water is provided as part of the accelerometer, a possible variant of the functional block diagram of which is shown in FIG. 3. Briefly describe the functional relationships of the blocks (see Fig. 3). A continuous stream of optical radiation from AI 1 through BC 2 is fed to a Y-shaped fiber optic splitter (BOP) 4, from the output of which also through BC 2 it goes to VOD 6. The short pulses of optical radiation formed from VOD 6 along the same BC 2 are again arrive at VOR 4, after passing through which another aircraft 2 branches off to FP 3. Electrical pulses from the output of FP 3 are fed to the electronic signal processing unit 5 of the WOD 6. Block 5 generates an information signal and, together with block 7, excites and supports circular motion ma Jammer in WATER 6.

 The proposed WATER operates as follows. In the initial state (with the power turned on in the absence of acceleration), a continuous stream of optical radiation generated by the AI is supplied to the water through the VOR through VS 2. The end of aircraft 2, cantileverly fixed in the housing 1, is cantilevered with IM 3 at its free end and is a pendulum-type oscillatory system. During the operation of the VOD, the end of the BC 2 console makes circular motions in the plane defined by the axis of curvature of the mirror 5. The circular motion of the pendulum is supported by the force acting on the MI 3 of the inhomogeneous pendulum field generated by the coils 6 when the current from the control unit 7 passes through them (alternately) (see Fig. 3). The range (radius) of the circular motion of the end of the BC 2 console can be from one to several millimeters.

 Each time, when the end of the console BC 2 crosses the axis of curvature of mirror 5, a part of the radiation emerging from the end face of BC 2 after reflection from mirror 5 returns to BC 2. This is explained by the rules of geometric optics, according to which when the object is located at double focal length from a concave spherical mirror (or, which is the same thing, at a distance equal to the radius of curvature of the mirror), its inverse isometric image is formed in the same plane. In the case of a cylindrical mirror, basically the same thing happens, only the image will be stretched along the mirror axis to 2Rtg 2, where R is the radius of curvature of the mirror and Θ is the aperture angle of the aircraft.

 Thus, four optical pulses are formed four times for each period of movement (revolution) of the pendulum, at the output of the VOD. Obviously, in the absence of acceleration on the water supply, the residence times of the pendulum on both sides of each of the two perpendicular optical axes of mirror 5 will be the same and, accordingly, the durations of the time intervals between the optical pulses generated by the water from the respective mirrors will be the same (see Fig. 4a).

 Under the action of acceleration on the water, the vector of which is parallel to the XOY plane (see Fig. 1), the equilibrium position of the pendulum is shifted (from the original) by a certain amount. The magnitude of this displacement is determined by the values of the acceleration acting on the water, IM 3 and the rigidity of the console of the end of aircraft 2. Due to the indicated displacement of the equilibrium position of the pendulum, its residence times on both sides of each of the optical axes of mirror 5 will no longer be the same. This means that in each of the two sequences of optical pulses (one of which corresponds to one part of the cylindrical mirror parallel, for example, the X axis, and the second to the second part of the mirror parallel to the Y axis), one of each pair of adjacent time intervals will increase its duration and the other will reduce it (see Fig. 4b). In this case, the total duration of two adjacent time intervals in each of the sequences (i.e., the time of the complete rotation of the pendulum) will remain unchanged. Obviously, the larger (smaller) the magnitude of the acceleration acting on the water, the correspondingly larger (smaller) will be the difference in duration between adjacent time intervals specified by the optical pulses in each of their sequences.

 Thus, the difference in the durations of two adjacent time intervals between pulses in each of the sequences at the input of the phase transition can serve as a measure of the projection of the acceleration acting on the water input on each of the two sensitivity axes (OX and OY), defined by the curvature axes of the cylindrical mirrors (naturally, the corresponding sensitivity axes are perpendicular to each of its “own” parts of the mirror). The sign of this difference will determine the direction of the acceleration vector (or its projection) - according to or against the chosen positive direction of the axis of sensitivity of the water.

 In order to unambiguously determine the sign of the difference, it is necessary to know in advance whether the position of the pendulum is shifted to one side or another from the initial one under the influence of acceleration on water. This problem is solved by determining the sign of the force action on the MI 3 from the side of the circuit for maintaining the circular motion of the pendulum (then the direction of the current in the inductors 6).

 Under the influence of acceleration on the water supply, the vector of which is directed along the sensitivity axis OZ (perpendicular to the plane of the mirror cutoff 5), the equilibrium position of the pendulum will not change and, accordingly, an increase (decrease) in neighboring time segments relative to each other will not occur in the pulse sequences considered above. However, this will change the time (period) of the pendulum, i.e. in this case, the information parameter will be not the difference in residence times on both sides of the corresponding optical axes of the mirror, but the time of rotation of the pendulum itself.

 With an arbitrary orientation of the acceleration vector, when its projections on all three axes of sensitivity of the OD are present, all of the above time intervals will change (see Fig. 4c), which allows for appropriate processing to determine the values and signs of all three projections of the acceleration vector.

 Obviously, the total value of the acceleration vector (its modulus and direction) is defined as the geometric sum of all its projections.

 The high accuracy of acceleration measurement by means of the proposed VOD is ensured by the possibility of high-precision measurement of time intervals between the corresponding optical pulses, as well as by the possibility of creating a high-quality oscillatory pendulum system (which in our case is ensured by using an IM console made of quartz aircraft as an elastic suspension). In addition, the independence of the metrological parameters of the VOD from the stability of the parameters of the optical and electrical elements that form the measuring optical path of the VOD and ensuring its operability contributes to the achievement of high measurement accuracy, since the measured value in the output signal of the VOD is not the energy parameters of its optical pulses, but using the duration of time intervals.

 For the formation of the shortest possible duration of the output optical pulses (to increase the accuracy of the start-stop circuit for measuring the duration of time intervals between optical pulses), single-mode aircraft with a light guide core diameter of ≈ 5-7 μm should be used as BC 2 (see Fig. 1) . When using 2 multimode aircraft as aircraft, to shorten the duration of the output optical pulses at the ends of the aircraft, modulating rasters from alternating transparent and opaque concentric circular bands can be fixed (see Fig. 2).

 We give an assessment of the metrological capabilities of the proposed water as a measurement transformation for building an accelerometer.

To simplify, we consider in the following possible cases of orientation of the acceleration vector:
1. The acceleration vector is parallel to the XOY plane and one of the sensitivity axes (for example, Y);
2. The acceleration vector is parallel to the XOY plane and is randomly oriented with sensitivity axes X and Y;
3. The acceleration vector is parallel to the sensitivity axis Z;
4. The acceleration vector is oriented arbitrarily with respect to the axes of sensitivity of the water.

 Case N 1.

 With a change in the magnitude of the acceleration, the durations of adjacent time intervals in the sequence of pulses reflected by a part of the mirror perpendicular to the sensitivity axis OY will change. In the sequence of pulses reflected by the second part of the mirror, the time intervals will not change. In other words, a zero result will be obtained in only one channel that determines the acceleration, the vector of which is directed along the OY axis (in the "Y" channel).

где - M - инертная масса на свободном конце консоли ВС, кг; L - длина консоли, м; E - модуль Юнга для материала консоли, H/м²; I - момент инерции поперечного сечения консоли, м⁴.Threshold sensitivity. The offset of the free end of the BC 2 console from the initial equilibrium position (in the absence of acceleration) under the action of acceleration a on the water input can be determined from the expression [4]:

where - M is the inert mass at the free end of the aircraft console, kg; L is the length of the console, m; E - Young's modulus for the console material, N / m ² ; I - moment of inertia of the cross section of the console, m ⁴ .

On the other hand, the projection of the circular motion of the end of the pendulum on the sensitivity axis OX is described by the expression:
x = Rsinωt, (2)
where R is the radius of revolution of the end of the pendulum, m; ω = 2πF — angular frequency, rad / s; F = 1 / T - linear frequency, 1 / s; T - pendulum rotation time, sec.

Очевидно, ΔT_пор = 4Δt_пор = 1/f_ген - условие регистрации порогового значения a.Based on the fact that the threshold shift console X _pores, under the effect of a water threshold acceleration a _{long long} x <R, from equation (1) we can write expression for Δt _far:

Obviously, ΔT _then = 4Δt _then = 1 / f _gene is a condition for registering the threshold value a.

Here ΔT _pore is the difference between the durations of the time intervals of the positive and negative semicircles of the pendulum revolution when its equilibrium is shifted under the action of a _pore by Δx _pores f _gene is the frequency of a stabilized high-frequency generator, the duration of the oscillation period of which is used as a measure when measuring the duration of time intervals between optical pulses at the output of the VOD.

Из уравнений (1-4) выразим пороговую величину ускорения, которая может быть зарегистрирована предлагаемым ВОД:

Оценку а_пор проведем для следующих значений входящих в (5) величин (консоль считаем кварцевым стержнем с размерами L • d = 50 • 0,125 мм²); E = 7 • 10¹⁰ H/м²; I = πd⁴/64 = 1,2•10^-17 м⁴; R = 2 • 10^-3 м; m = 10^-2 кг; L = 5 • 10^-2 м; f_ген = 5 • 10⁷ Гц.Own (resonant) frequency of the rotational motion of the pendulum [5]:

From equations (1-4) we express the threshold value of the acceleration, which can be recorded by the proposed water:

We will evaluate a _pore for the following values of the quantities included in (5) (we consider the cantilever as a quartz rod with dimensions L • d = 50 • 0.125 mm ² ); E = 7 • 10 ¹⁰ N / m ² ; I = πd ^4/64 = 1,2 • 10 ^-17 m ^4; R = 2 • 10 ^-3 m; m = 10 ^-2 kg; L = 5 • 10 ^-2 m; f _gene = 5 • 10 ⁷ Hz.

Динамический диапазон измеряемых посредством предлагаемого ВОД ускорений:

Очевидно, быстродействие ВОД будет определяться периодом обращения консоли:

Случай N 2.Substituting the indicated values into expression (5), we obtain:
a _pore = 5.6 • 10 ^-8 m / s ² = 5.7 • 10 ^-9 g. (6)
The maximum value a _max , which can be measured by the proposed WATER, obviously, can be determined from the condition:

The dynamic range measured by the proposed water acceleration:

Obviously, the speed of the water will be determined by the period of the console:

Case N 2.

 This case does not have a fundamental difference from the above. In this case, a nonzero result will be obtained in both channels (both in the “X” - and in the “Y” channels). Obviously, case 2 can be interpreted as a simple superposition of two cases 1. The full acceleration value and its orientation with respect to the sensitivity axes OX and OY will be defined in the processing unit as the geometric (vector) sum of the acceleration values obtained in "X" and in "Y" channels.

 Case N 3.

 This case is fundamentally different from the two above. When the acceleration vector is directed along the Z axis, the initial equilibrium position of the pendulum (in the absence of an acceleration effect on the water input) is not violated and, accordingly, in the “X” and “Y” channels, the result of the action of the acceleration on the water supply will not be recorded. At the same time, there will be a general change in the intrinsic (resonant) frequency of rotation of the pendulum, i.e. now the information parameter is not the difference in the half-cycle durations (as in the previous cases), but the duration of the rotation period (time of the full revolution) of the pendulum, the measurement of which is carried out in the third channel (“Z” channel) of the processing unit. Let us evaluate the main metrological parameters of water for its third axis of sensitivity, OZ.

Очевидно, условие регистрации пороговой величины ускорения можно записать в виде:

Преобразуя (11) с учетом (1), (10) и пользуясь формулами приближенного вычисления, получим:

Подставляя численные значения входящих в (12) величин, получим:
a_пор ≈ 7,2 • 10^-7 м/с ≈ 7,3 • 10^-8 g.Threshold sensitivity. When exposed to acceleration along the OZ axis, the expression for the period of revolution of the pendulum will take the form:

Obviously, the condition for registering the threshold value of acceleration can be written in the form:

Transforming (11) taking into account (1), (10) and using the approximate calculation formulas, we obtain:

Substituting the numerical values of the quantities included in (12), we obtain:
a _pore ≈ 7.2 • 10 ^-7 m / s ≈ 7.3 • 10 ^-8 g.

Динамический диапазон измеряемых ускорений в этом случае составит:
N = 4 • 10⁶. (14)
Быстродействие ВОД, как и прежде, будет определяться периодом обращения консоли.As the maximum value of acceleration a _max , which can be measured by the proposed water, we take its value at which the period of rotation of the pendulum will increase (decrease), for example, by half (this condition is obviously not hard). From this condition:

The dynamic range of measured accelerations in this case will be:
N = 4 • 10 ⁶ . (14)
The performance of the water, as before, will be determined by the period of the console.

 Case N 4.

 This is the most common case - a non-zero result will be obtained in all three channels ("X", "Y" and "Z"). The resulting value of the full acceleration vector and its orientation relative to the sensitivity axes will be determined in the processing unit as the geometric sum of all three components. Obviously, the appearance of the component of the acceleration vector directed along the OZ axis will cause changes in the sensitivity of the VOD along the OX and OY axes and, accordingly, will cause changes in the samples of the channels "X" and "Y" even with the constant values of the components of the acceleration vector along these axes. It follows from the foregoing that the processing unit must correct the scale factors corresponding to the OX and OY axes, in accordance with the magnitude of the component of the acceleration vector along the OZ axis.

As follows from the above expressions, by a targeted change in the design parameters of the VOD and the measuring frequency f _{gene, the} basic metrological parameters of the VOD accelerometer can be widely changed.

 The possibilities of using the proposed water can be further expanded by electronic processing of its signals. So, for example, integrating over time the results of acceleration measurements, it is easy to carry out high-precision measurement of the relative speed of an object carrying water or (by double integration) its spatial displacement, i.e. to create high-precision navigation systems (spatial orientation) for autonomous (not related to any external reference points) mobile vehicles (submarines, long-range homing missiles, spacecraft, etc.).

Literature
1. Soref R., McMahon DH Tilting-mirror Fiber Optic Acceleroment // Appl. Opt., 1984, v. 23, p. 486-491.

 2. Application EPO N 0251048, G 01 P 15/08, 1988.

 3. P. A. Demyanenko. "The ultimate capabilities of similar fiber-optic sensors as part of the OSI." - Radio engineering, 1988 N 2, p. 88-90.

 3. S.P. Timoshenko, J. Goodyear. Theory of elasticity. Per. from English / Ed. G. S. Shapiro. - 2nd ed. - M .: Science. The main edition of the physical and mathematical literature, 1979, p. 62.

 5. S.P. Timoshenko. Fluctuations in engineering. - M.: Fizmatgiz, 1959, p. 251.

Claims (1)

 Fiber-optic acceleration sensor, comprising a housing with a reflector fixed therein, a fiber optic fiber, the end of which is cantilevered in the housing, an inertial mass mounted on the free end of the fiber optic console located in the through hole made in the inertial mass, and the end of the free end of the fiber console the fiber is located above the reflector, characterized in that the introduced inductor installed in the housing symmetrically to the axis of the fiber, the reflector is made in the form a concave mirror formed by two cylindrical surfaces, while the axes of the cylindrical surfaces are mutually perpendicular and intersect with the axis of the fiber at right angles above the cut plane of the concave mirror, and the center of mass of the inertial mass made of soft magnetic material lies on the axis of the fiber.

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