CN112815935A - Device and method for evaluating dynamic characteristics of fiber-optic gyroscope - Google Patents
Device and method for evaluating dynamic characteristics of fiber-optic gyroscope Download PDFInfo
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Abstract
The invention discloses a device and a method for evaluating dynamic characteristics of a fiber-optic gyroscope. Wherein the evaluation method when executed comprises creating an equivalent dynamic model of a digital closed-loop fiber optic gyroscope; establishing a simplified model according to the equivalent dynamic model; obtaining a transfer function of the simplified model; obtaining a bandwidth of the simplified model according to the transfer function, and obtaining a phase lag according to the bandwidth and an external angular frequency; and introducing all actual parameters of the digital closed-loop optical fiber gyroscope, and acquiring the relation between the value of the bandwidth and at least one actual parameter.
Description
Technical Field
The invention relates to the field of attitude measurement, servo tracking and control of a rate-level fiber optic gyroscope, in particular to a device and a method for evaluating dynamic characteristics of a fiber optic gyroscope.
Background
Fiber Optic gyroscopic sensors (FOG) are a new type of angular rate sensor developed based on the Sagnac effect. The technical development of the fiber-optic gyroscope is relatively mature, and engineering series fiber-optic gyroscope products with different precisions are widely applied.
In recent years, optical fiber gyro sensors have been widely used in the fields of attitude measurement, servo control, photoelectric tracking, etc. because of their characteristics of good angular velocity tracking characteristics, small size, and high accuracy.
With the upgrading and upgrading of various tracking systems, the tracking quality of the control system is continuously improved by external requirements, and the control system also puts higher requirements on the dynamic (bandwidth) performance requirements of the fiber-optic gyroscope sensor.
Different from the traditional mechanical gyro sensor, the optical fiber gyro sensor takes light as a transmission medium, theoretically has extremely high response speed and extremely high bandwidth, the bandwidth of the rate-level optical fiber gyro sensor can reach more than dozens of kHz, but is limited by a signal processing scheme and the like, and the actual application bandwidth is reduced to 1 Khz-10 Khz.
Considering the serial port output form of the fiber-optic gyroscope, the conventional use updating frequency is 500 hz-1 kHz, and the gyroscope demodulation data needs to be subjected to integration processing before being output, so the actual measurement bandwidth is only about 100-300 hz.
In addition, researches show that the higher the bandwidth is, the smaller the phase lag is, the larger the transient noise of the fiber-optic gyroscope is, and the larger the noise is, the more the control precision is influenced; conversely, if the bandwidth characteristic of the fiber optic gyroscope is reduced, the control accuracy will be improved as the phase lag is larger. Therefore, according to the specific application context, the bandwidth characteristics of the fiber-optic gyroscope need to be reasonably designed, and mutual balance between angular frequency tracking capability and precision indexes is realized.
The current test method for evaluating the dynamic performance of the fiber-optic gyroscope has the following modes.
The test method of the fiber-optic gyroscope based on the angular vibration table has the advantages that the angular vibration table applied in the test method can only generate angular vibration of 100 hz-300 hz, and the test method has the defects of low test capability and high test cost.
Although the testing method of the fiber-optic gyroscope based on the magneto-optic Faraday effect can overcome the problem of low testing capability of an angular vibration table, gyroscope information with low magnetic field sensitivity is easily submerged by noise generated by the magneto-optic effect, so that the measurement cannot be carried out.
The test method of the fiber-optic gyroscope based on the voltage analog signal simulates the angular vibration condition of an angular vibration table through a signal generator, and then superposes a generated signal on a gyroscope circuit to realize dynamic measurement; however, the testing method also has the problem that the signal generator introduces large noise into the gyroscope, and the measuring precision is influenced.
Disclosure of Invention
The embodiment of the invention at least discloses a method for evaluating the dynamic performance of a fiber-optic gyroscope. The evaluation method establishes an equivalent dynamic model of the digital closed-loop fiber-optic gyroscope, deduces a system transfer function of the digital closed-loop fiber-optic gyroscope, and analyzes the real frequency characteristic situation of the fiber-optic gyroscope from a theoretical level, so that various main factors influencing the bandwidth are analyzed, and important references are provided for the customized dynamic performance design and evaluation of the fiber-optic gyroscope.
In order to achieve the above, the evaluation method in this embodiment is executed to include:
s100, creating an equivalent dynamic model of the digital closed-loop optical fiber gyroscope;
s210, establishing a simplified model according to the equivalent dynamic model;
s220, obtaining a transfer function of the simplified model;
s230, acquiring the bandwidth of the simplified model according to the transfer function, and acquiring phase lag according to the bandwidth and the external angular frequency;
s300, introducing all actual parameters of the digital closed-loop optical fiber gyroscope, and acquiring the relation between the value of the bandwidth and at least one actual parameter.
In some embodiments disclosed in the present invention, the equivalent dynamic model includes a forward channel module, a photoelectric conversion module, a pre-amplification module, an analog-to-digital conversion module, a signal demodulation module, a digital integration module, a feedback step wave production module, a digital-to-analog conversion module, a post-amplification module, and a phase modulation module;
the forward channel module is configured to output interference beams carrying phase differences according to an input angular rate; the photoelectric conversion module is configured to photoelectrically convert the interference light beam into a voltage analog signal; the pre-amplification module is configured to amplify the voltage analog signal; the analog-to-digital conversion module is configured to convert the amplified voltage analog signal into a digital signal; the signal demodulation module is configured to demodulate the digital signal into a digital phase error signal; the digital integration module is configured to integrate and operate the digital phase error into an output angular rate; the feedback step wave production module generates a feedback digital signal according to the output angular rate; the digital-to-analog conversion module is configured to convert the feedback digital signal into a feedback analog signal; the post-amplification module is configured to amplify the feedback analog signal; the phase modulation module is configured to phase modulate the interference beam according to a feedback analog signal.
In some embodiments of the present disclosure, a square wave bias modulation is introduced between the forward channel module and the photoelectric conversion module to obtain the interference light beam in a sinusoidal relationship, and the sinusoidal relationship of the interference light beam in the equivalent dynamic model is considered as a linear relationship.
In some embodiments of the present disclosure of the invention,
in S210, the simplified front channel module is represented by a proportion link K1; the simplified photoelectric conversion module, the pre-amplification module and the signal demodulation module are represented by a proportion element K2; the analog-to-digital conversion module is simplified by a proportional element K3; the simplified digital integration block is represented by the proportional element K4; the simplified feedback step wave production module, the simplified digital-to-analog conversion module, the simplified post-amplification module and the simplified phase modulation module are represented by a proportion link K5; the simplified model comprises an open-loop module, a feedback module, a closed-loop module and a delay module; representing an open-loop scaling factor G of the open-loop module according to a product of K1, K2, K3; representing a feedback coefficient K of the feedback module according to K4; representing the inverse M of the closed loop scaling factor of the closed loop module in accordance with K5/K1; the operator symbol of the delay unit time of the delay module is D;
in S220, the transfer function is
Y(s) is the output of the simplified model, W(s) is the input of the simplified model, τcτ is the transit time.
In some embodiments disclosed in the present invention, obtaining the links representing each proportion according to the equivalent dynamic model is: proportional link K 12 pi LD/lambdac, L is the fiber length, D is the equivalent diameter of the fiber ring, lambada is the central wavelength of the light source, and c is the speed of light; proportional link K2＝2KdemoRfKqηKLP0sin(φb)，KdemoFor demodulation of the coefficients, RfFor the photo-detector across resistance, KqIs the pre-amplification factor, eta is the photoelectric detector conversion efficiency, KLFor the loss of the optical path from the light source to the photodetector, P0Is the output power of the light source, delta phibIs the offset phase; proportional link K3＝KA/D，KA/DIs an analog/digital conversion coefficient; proportional link K4＝Kp KpIs a proportional control coefficient; proportional link K5＝KmKbKD/A，KmTo modulate a system, KbTo a post-amplification factor, KD/AAre digital/analog conversion coefficients.
In some embodiments of the present disclosure, the bandwidth in S230 is represented as
The phase lag is expressed as
TdIs a pure lag time, omegaiFor externally introduced angular frequencies, T is the time delay caused by the frequency characteristics.
In some embodiments of the present disclosure, the time delay in S230 is represented by T-1/2 pibW(ii) a The phase lag is expressed as
In some embodiments of the present disclosure, the dynamic model is generated, based on parameters of the equivalent dynamic model,
the feedback coefficient is
The inverse of the closed loop scaling factor is
The bandwidth is
S300, according to all actual parameters of the digital closed-loop optical fiber gyroscope, determining that the value of the bandwidth is in negative correlation with tau.
The embodiment of the invention at least discloses a device for evaluating the dynamic performance of a fiber-optic gyroscope.
The evaluation device comprises an equivalent model module, a model simplification module and a model analysis module;
the equivalent model module is configured to create an equivalent dynamic model of the digital closed-loop fiber optic gyroscope;
the model simplification module is configured to establish a simplified model according to the equivalent dynamic model, obtain a transfer function of the simplified model, obtain a bandwidth of the simplified model according to the transfer function, and obtain a phase lag according to the bandwidth and an external angular frequency;
the model analysis module is configured to introduce all actual parameters of the digital closed-loop fiber optic gyroscope and obtain a relationship between a value of the bandwidth and at least one of the actual parameters. In view of the above, other features and advantages of the disclosed exemplary embodiments will become apparent from the following detailed description of the disclosed exemplary embodiments, which proceeds with reference to the accompanying drawings.
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In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
FIG. 1 is a basic schematic block diagram of a digital closed-loop fiber optic gyroscope according to the present embodiment;
FIG. 2 is a diagram illustrating an equivalent dynamic model in the present embodiment;
FIG. 3 is a schematic diagram of a simplified model according to the present embodiment;
FIG. 4 is a linear schematic block diagram of a digital closed-loop fiber optic gyroscope according to the present embodiment;
fig. 5 is a schematic diagram illustrating the verification of the bandwidth test at different update frequencies in the present embodiment.
The attached drawings are marked as follows: 1. an optical unit 1; 101. a light source; 102. a coupler; 103. a Y waveguide; 104. an optical fiber loop; 105. a photodetector; 2. a circuit unit; 201. an A/D conversion circuit; 202. an FPGA; 203. a D/A conversion circuit; 301. a forward channel module; 302. a photoelectric conversion module; 303. a pre-amplification module; 304. an A/D conversion module; 305. a signal demodulation module; 306. a digital integration module; 307. a feedback step wave production module; 308. a D/A conversion module; 309. a post-amplification module; 310. and a phase modulation module.
Detailed Description
Reference will now be made in detail to the embodiments, examples of which are illustrated in the accompanying drawings. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various described embodiments. It will be apparent, however, to one skilled in the art that the various described embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail as not to unnecessarily obscure aspects of the embodiments.
It will also be understood that, although the terms first, second, etc. may be used herein to describe various elements in some cases, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first contact can be termed a second contact, and, similarly, a second contact can be termed a first contact, without departing from the scope of the various described embodiments. The first contact and the second contact are both contacts, but they are not the same contact.
The embodiment discloses a method for evaluating dynamic performance of a fiber-optic gyroscope.
Referring to fig. 1, the fiber optic gyroscope in the present embodiment is a digital closed-loop fiber optic gyroscope. The digital closed-loop fiber-optic gyroscope comprises an optical unit 1 and a circuit unit 2. The optical unit 1 includes a light source 101, a coupler 102, a Y-wave 103 waveguide, a fiber ring 104, and a photodetector 105. The circuit unit 2 includes a pre-amplifier circuit, an a/D conversion circuit 201, an FPGA, a D/a conversion circuit 203, and a post-amplifier circuit.
When the digital closed-loop fiber optic gyroscope rotates relative to the inertial space, the light beam of the light source 101 emitted by the light source 101 is split into two identical molecular beams by the coupler 102, and the two molecular beams enter the fiber loop 104 after being guided by the Y wave 103 and propagate in the fiber loop 104 in opposite directions to form an interference beam. At this time, the interference beam carries a phase difference proportional to the rotation speed, and the interference beam enters the photodetector 105 after passing through the Y-wave 103 and the coupler 102.
The interference light beam is converted into an electrical signal by the photodetector 105, the electrical signal is received by the processing circuit in real time and generates a corresponding compensation voltage, and the compensation voltage is loaded on the Y-wave 103 waveguide, so that the interference light beam generates a compensation phase. When the closed loop of the digital closed-loop fiber optic gyroscope is stable, the phase difference generated by the compensation phase and the rotating speed is equal, the compensation voltage is in direct proportion to the compensation phase, namely, the compensation value can linearly reflect the rotating speed information of the digital closed-loop fiber optic gyroscope in the embodiment.
In this embodiment, the digital closed-loop fiber optic gyroscope may be divided into several parts according to internal functional design, specifically, angular rate/phase shift conversion, optical interference, photoelectric conversion, pre-amplification, a/D conversion, digital demodulation, digital integration, step wave generation, D/a conversion, post-amplification, phase modulation, and the like.
In this regard, the evaluation method of the present embodiment is executed in the first step S100.
S100, an equivalent mathematical model is created according to functions of all parts of the digital closed-loop optical fiber gyroscope. Referring to fig. 2, the mathematical models in the present embodiment are a forward channel module 301, a photoelectric conversion module 302, a pre-amplification module 303, an a/D conversion module 304, a signal demodulation module 305, a digital integration module 306, a feedback step wave generation module 307, a D/a conversion module 308, a post-amplification module 309, and a phase modulation module 310, respectively.
Meanwhile, discrete time units are implied in fig. 2, and the physical meaning of each module parameter is shown in the following table.
| Parameter(s) | Physical significance | Parameter(s) | Physical significance |
| Ω | Input angular rate | P0 | Output power of light source |
| Δφs | Sagnac phase shift | KL | Optical path loss from light source to detector |
| Δφf | Feedback phase shift | Kq | Pre magnification factor |
| Δφb | Offset phase | KA/D | a/D conversion coefficient |
| L | Length of optical fiber | Kdemo | Demodulation coefficient |
| D | Equivalent diameter of fiber ring 104 | Kp | Coefficient of proportional control |
| λ | Center wavelength of light source | KD/A | Digital/analog conversion coefficient |
| c | Speed of light | Kb | Post-amplification factor |
| Rf | Detector transimpedance | Km | Modulation factor |
| η | Photoelectric conversion efficiency of detector | τ | Transit time |
In particular, the forward path module 301 is shown outputting interference beams carrying phase differences according to the input angular rate. The photoelectric conversion module 302 is shown to photoelectrically convert the interference light beam into a beam voltage analog signal. The pre-amplification module 303 is shown amplifying the beam voltage analog signal. The a/D conversion module 304 converts the amplified beam voltage analog signal into a beam digital signal. The signal demodulation module 305 is shown as demodulating the digital signal into an angular rate signal. The digital integration block 306 operates to integrate the angular rate signal into an output angular rate. The feedback step wave production module 307 generates a feedback digital signal according to the output angular rate. The D/a conversion module 308 converts the feedback digital signal into a feedback analog signal. The post-amplification block 309 is shown amplifying the feedback analog signal. The phase modulation module 310 is shown phase modulating the interfering beam according to the feedback analog signal.
Meanwhile, considering that the interference light beam output by the forward channel module 301 is in cosine function relationship, quantization error exists in a/D conversion, and non-linear factors such as truncation effect exist in data processing, the whole system of the equivalent dynamic model belongs to a non-linear system, which is not beneficial to simulation analysis.
The embodiment linearizes the equivalent dynamical model. Square wave bias modulation is added between the forward channel module 301 and the photoelectric conversion module 302, so that the interference light beams are converted into a sinusoidal relationship, and when the phase shift of the digital closed-loop fiber-optic gyroscope is very small, the sinusoidal relationship of the interference light beams is regarded as a linear relationship. The photodetector 105 can be expressed in a linear relationship according to the photoelectric conversion efficiency, the transimpedance, the pre-amplification gain, and the like.
Then, in this embodiment, Sagnac phase difference caused by input angular rate in the forward channel module 301 is reduced to a proportional element K1＝2πLD/λc。
Meanwhile, in this embodiment, the equivalent photoelectric conversion of the photoelectric conversion module 302, the equivalent demodulation part of the signal demodulation module 305, the equivalent interference part of the forward channel module 301, and the equivalent pre-amplification part of the pre-amplification module 303 can be simply expressed as a proportional element K2＝2KdemoRfKqηKLP0sin(φb)。
Meanwhile, when the quantization error of the A/D converter is not considered, the equivalent A/D conversion part of the A/D conversion module 304 can be simplified to a proportional element K3＝KA/DAnd (4) showing. The integral part of the digital integral module 306 can be simplified and expressed as a proportional element K by a discrete transfer function4＝Kp。
Further, in this embodiment, the combination of the equivalent parts of the feed step wave generation module, the D/a conversion module 308, the post-amplification module 309 and the phase modulation module 310 represents a feedback channel of a system. The phase slope generation process in the feedback channel can be regarded as an integral part, the D/A conversion part can be represented by a proportional element and a zero-order retainer, the post-placement part and the phase modulation part are proportional differential processes, and therefore the whole feedback channel can be simplified and represented as a proportional element K5＝KmKbKD/A。
Further, the evaluation method in this embodiment is implemented in the following step S210 when executed.
S210, establishing a simplified model according to the equivalent dynamic model. Specifically, in the embodiment, the evaluation method further simplifies the equivalent dynamic model by equivalent approximation and parameter combination according to the automatic control principle, and the simplified model is shown in fig. 3.
Referring to fig. 3, the simplified model in this embodiment includes an open-loop module, a feedback module, a closed-loop module, and a delay module.
Specifically, the open-loop scaling factor G of the open-loop module is expressed as G ═ K1K2K3Wherein each parameter is determined by the hardware design of the digital closed-loop optical fiber gyroscope. The feedback coefficient K of the feedback module is expressed as K ═ K4And the parameters can be adjusted in the digital closed-loop optical fiber gyroscope. The inverse of the closed loop scaling factor of the closed loop module, M, is expressed as M ═ K5/K1Wherein each parameter is determined by the hardware design of the digital closed-loop optical fiber gyroscope. And the operator symbol of the delay unit time of the delay module is D.
Furthermore, the evaluation method in this embodiment is executed in the following step S220.
S220 obtains a transfer function of the simplified model.
Specifically, the transfer function of the digital closed-loop optical fiber gyroscope can be obtained by deriving a simplified model
In the formula taucτ/GKM, y(s) is the output of the simplified model, w(s) is the input of the simplified model, τcτ is the transit time.
S230 obtains the bandwidth of the simplified model from the transfer function and obtains the phase lag from the bandwidth and the external angular frequency.
Specifically, the transfer function shows that the simplified digital closed-loop fiber optic gyroscope is a typical first-order system and reflects the bandwidth B of an important index of dynamic characteristicsWThe calculation formula can be expressed as:
Thereafter, the evaluation method in the present embodiment is executed with a post-implementation step S300.
S300, all actual parameters of the digital closed-loop optical fiber gyroscope are introduced, and the relation between the value of the bandwidth and at least one actual parameter is obtained.
Specifically, the open loop scaling factor G may be expressed as
Meanwhile, the setting is already carried out through a multiplier and shift filtering in the program; the inverse M of the closed loop scaling factor is expressed as
Then bandwidth BWCan be further expressed as
As can be seen from the above equation, the bandwidth of the digital closed-loop fiber optic gyroscope is mainly determined by parameters G, K, M and τ, and the larger the GKM product is, the smaller τ is, the larger the system bandwidth is.
Therefore, when the hardware of the digital closed-loop fiber optic gyroscope is designed, G, M is greatly influenced by hardware factors, and once the processing circuit of the digital closed-loop fiber optic gyroscope is designed, the foregoing parameters are fixed values, so that the digital closed-loop fiber optic gyroscope in this embodiment can substantially optimize K through software4And parameters are adopted to realize the improvement of the bandwidth.
In addition, is composed of
It is known that bandwidth is directly related to tau, and tau is related to the length of the optical fiber, the shorter the optical fiber, the smaller tau and the larger bandwidth, so the rate type optical fiber gyro with longer optical fiber length generally has better performanceDynamic performance.
Through the technical scheme, the fiber-optic gyroscope has the characteristics of high bandwidth and excellent dynamic performance, but the bandwidth exertion of the fiber-optic gyroscope is influenced by the limitation of the updating frequency of the serial port output data, so that the transmission baud rate of the gyroscope is increased, the updating frequency of the gyroscope is improved, and the angular frequency tracking performance of the fiber-optic gyroscope can be effectively improved.
Meanwhile, in order to further verify the correctness of the equivalent dynamic model, according to the digital step wave feedback working principle of the digital closed-loop fiber-optic gyroscope, a semi-physical simulation angular vibration test condition is selected to complete the bandwidth simulation test of the fiber-optic gyroscope.
Referring to fig. 4, if the angular vibration table is used to perform the bandwidth test, the height of the step wave is obtained by the Sagnac effect, i.e. the input is w (z), and if the analog angular vibration signal is directly added to the interior of the gyro program, i.e. the adding position is p (z), the transfer functions between the two excitation introductions and the gyro output can be respectively w (z)
And
as can be seen from the comparison of the above two equations, the two equations have the same form, and have the same dynamic characteristics with only one difference of the proportionality coefficient M.
Through the verification of the correctness of the equivalent dynamic model, when the digital closed-loop fiber-optic gyroscope is tested on the angular vibration table, the digital closed-loop fiber-optic gyroscope can be equivalently added with a digitized sinusoidal signal on the height of the feedback step wave, and the amplitude and the frequency of the sinusoidal signal can be equivalently the vibration amplitude and the frequency of the angular vibration table, so that the effectiveness of the evaluation method in the present instance is further explained.
By creating the equivalent dynamic model in the embodiment, the angular frequency tracking performance of the fiber-optic gyroscope can be evaluated by bringing in actual physical parameters of the fiber-optic gyroscope during angular frequency tracking characteristic analysis, and the operability is high. Meanwhile, the evaluation method in the embodiment is constructed by deducing the semi-physical simulation model, so that the specific dynamic performance of the fiber-optic gyroscope can be quickly and conveniently verified, and the product can be quickly shaped conveniently.
For a clear and complete explanation of the evaluation method in this example; the present embodiment exemplifies the evaluation method in the present embodiment by taking a certain type of fiber-optic gyroscope in a laboratory. The main parameters of the fiber optic gyroscope are shown in the following table.
Based on the main parameters of the fiber-optic gyroscope, the gyroscope bandwidth B of the fiber-optic gyroscope in this embodimentW2.92kHz, and the time delay T caused by the frequency characteristic of the gyro is 1/2 pi BWThe bandwidth characteristic of the fiber-optic gyroscope is quantitatively evaluated at 54.5 mu s.
Meanwhile, the implementation result shows that the delay caused by the amplitude-frequency characteristic of the gyroscope is very small without considering the transmission delay. The rate type fiber optic gyroscope has high bandwidth which can reach over kHz, so that the fiber optic gyroscope has excellent dynamic performance.
In order to further verify the correctness of the equivalent dynamic model, in this embodiment, an additional signal is a digital sinusoidal signal when the fiber-optic gyroscope performs the analog angular vibration test, as shown in fig. 4, each period has 12 sampling points, each sampling point is held by a zero-order holder, and the holding time and the period of the sinusoidal function are controlled by counting the a/D sampling periods of the program. The amplitude of the applied signal is calibrated by applying a fixed bias within the program and based on the gyro output.
According to an equivalent calculation, the A/D sampling period count of 1400000 corresponds to a time of 1s, and is added to the program at an analog sine amplitude of + -100, which is about + -20 deg./s, so that 12 discrete values of the sine in the program take 0, 50, 86, 100, 86, 50, 0, -50, -86, -100, -86, -50, respectively.
Then, the data of the fiber-optic gyroscope is collected at 230400bps by using the updating frequency of 1kHz, that is, the collection frequency covers the angular vibration frequency of the angular vibration table, and the fitted curve is as shown in fig. 5 (a).
Considering that the output updating frequency of the fiber-optic gyroscope is only 1kHz, the gyroscope output delay is increased to limit the gyroscope bandwidth test, the gyroscope output updating frequency is increased to 4kHz, the baud rate is increased to 921600pbs, and the influence of the gyroscope output delay on the bandwidth is further reduced.
The bandwidth test fitting curve is shown in fig. 5(b), and it can be seen that the gyro bandwidth is greater than 1.7 kHz. The transmission baud rate of the gyroscope is improved, the updating frequency is improved, the high-bandwidth performance of the fiber-optic gyroscope can be effectively exerted, the equivalent dynamic model is consistent with the theoretical analysis result of the equivalent dynamic model, and the correctness of the equivalent dynamic model is verified.
Meanwhile, the embodiment discloses a device for evaluating the dynamic performance of the fiber-optic gyroscope. The evaluation device comprises an equivalent model module, a model simplification module and a model analysis module. When the modules in the evaluation device are implemented, one or more steps of the evaluation method in the embodiment are respectively executed.
Specifically, the equivalent model module is configured to create an equivalent dynamic model of the digital closed-loop fiber optic gyroscope. The model reduction module is configured to build a reduction model from the equivalent dynamic model, and to obtain a transfer function of the reduction model, and to obtain a bandwidth of the reduction model from the transfer function, and to obtain a phase lag from the bandwidth and the external angular frequency. The model analysis module is configured to introduce all actual parameters of the digital closed-loop fiber optic gyroscope and acquire the relationship between the value of the bandwidth and at least one actual parameter.
As used herein, the terms "comprises," comprising, "and the like are to be construed as open-ended inclusions, i.e.," including, but not limited to. The term "for" should be understood as "at least partially for". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first," "second," and the like may refer to different or the same object. Other explicit and implicit definitions may also be included herein.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (9)
1. A method for evaluating dynamic performance of a fiber-optic gyroscope is characterized in that,
the evaluation method when executed comprises:
s100, creating an equivalent dynamic model of the digital closed-loop optical fiber gyroscope;
s210, establishing a simplified model according to the equivalent dynamic model;
s220, obtaining a transfer function of the simplified model;
s230, acquiring the bandwidth of the simplified model according to the transfer function, and acquiring phase lag according to the bandwidth and the external angular frequency;
s300, introducing all actual parameters of the digital closed-loop optical fiber gyroscope, and acquiring the relation between the value of the bandwidth and at least one actual parameter.
2. The method of evaluating the dynamic performance of a fiber-optic gyroscope of claim 1,
the equivalent dynamic model comprises a forward channel module, a photoelectric conversion module, a pre-amplification module, an analog-to-digital conversion module, a signal demodulation module, a digital integration module, a feedback step wave production module, a digital-to-analog conversion module, a post-amplification module and a phase modulation module;
the forward channel module is configured to output interference beams carrying phase differences according to an input angular rate; the photoelectric conversion module is configured to photoelectrically convert the interference light beam into a voltage analog signal; the pre-amplification module is configured to amplify the voltage analog signal; the analog-to-digital conversion module is configured to convert the amplified voltage analog signal into a digital signal; the signal demodulation module is configured to demodulate the digital signal into a digital phase error signal; the digital integration module is configured to integrate and operate the digital phase error into an output angular rate; the feedback step wave production module generates a feedback digital signal according to the output angular rate; the digital-to-analog conversion module is configured to convert the feedback digital signal into a feedback analog signal; the post-amplification module is configured to amplify the feedback analog signal; the phase modulation module is configured to phase modulate the interference beam according to a feedback analog signal.
3. The method of evaluating the dynamic performance of a fiber-optic gyroscope of claim 2,
introducing square wave bias modulation between the forward channel module and the photoelectric conversion module to obtain the interference light beams in a sine relationship, and regarding the sine relationship of the interference light beams in the equivalent dynamic model as a linear relationship.
4. The method of claim 3, wherein the evaluation of the dynamic performance of the fiber-optic gyroscope is performed,
in the step S210, the process is carried out,
the reduced antecedent channel module is represented by the proportional element K1;
the simplified photoelectric conversion module, the pre-amplification module and the signal demodulation module are represented by a proportion element K2;
the analog-to-digital conversion module is simplified by a proportional element K3;
the simplified digital integration block is represented by the proportional element K4;
the simplified feedback step wave production module, the simplified digital-to-analog conversion module, the simplified post-amplification module and the simplified phase modulation module are represented by a proportion link K5;
the simplified model comprises an open-loop module, a feedback module, a closed-loop module and a delay module;
representing an open-loop scaling factor G of the open-loop module according to a product of K1, K2, K3;
representing a feedback coefficient K of the feedback module according to K4;
representing the inverse M of the closed loop scaling factor of the closed loop module in accordance with K5/K1;
the operator symbol of the delay unit time of the delay module is D;
in S220, the transfer function is
Y(s) is the output of the simplified model, W(s) is the input of the simplified model, τcτ is the transit time.
5. The method of evaluating the dynamic performance of a fiber-optic gyroscope of claim 4,
obtaining links representing all proportions according to the equivalent dynamic model as follows:
proportional link K12 pi LD/lambdac, L is the fiber length, D is the equivalent diameter of the fiber ring, lambada is the central wavelength of the light source, and c is the speed of light;
proportional link K2＝2KdemoRfKqηKLP0sin(φb)，KdemoFor demodulation of the coefficients, RfFor the photo-detector across resistance, KqIs the pre-amplification factor, eta is the photoelectric detector conversion efficiency, KLFor the loss of the optical path from the light source to the photodetector, P0Is the output power of the light source, delta phibIs the offset phase;
proportional link K3＝KA/D，KA/DIs an analog/digital conversion coefficient;
proportional link K4＝Kp，KpIs a proportional control coefficient;
proportional link K5＝KmKbKD/A，KmTo modulate a system, KbTo a post-amplification factor, KD/AAre digital/analog conversion coefficients.
6. The method of evaluating the dynamic performance of a fiber-optic gyroscope of claim 5,
the bandwidth in S230 is represented as
The phase lag is expressed as
TdIs a pure lag time, omegaiFor externally introduced angular frequencies, T is the time delay caused by the frequency characteristics.
7. The method of evaluating the dynamic performance of a fiber-optic gyroscope of claim 6,
the time delay is denoted as T-1/2 pib in S230W；
The phase lag is expressed as
8. The method of evaluating the dynamic performance of a fiber-optic gyroscope of claim 6,
based on the parameters of the equivalent dynamic model,
the feedback coefficient is
The inverse of the closed loop scaling factor is
The bandwidth is
S300, according to all actual parameters of the digital closed-loop optical fiber gyroscope, determining that the value of the bandwidth is in negative correlation with tau.
9. A device for evaluating dynamic performance of a fiber-optic gyroscope is characterized in that,
the evaluation device comprises an equivalent model module, a model simplification module and a model analysis module;
the equivalent model module is configured to create an equivalent dynamic model of the digital closed-loop fiber optic gyroscope;
the model simplification module is configured to establish a simplified model according to the equivalent dynamic model, obtain a transfer function of the simplified model, obtain a bandwidth of the simplified model according to the transfer function, and obtain a phase lag according to the bandwidth and an external angular frequency;
the model analysis module is configured to introduce all actual parameters of the digital closed-loop fiber optic gyroscope and obtain a relationship between a value of the bandwidth and at least one of the actual parameters.
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