System and method for realizing high-reliability fiber optic gyroscope eigenfrequency using triple mode redundancy

Abstract

The present invention discloses a system for realizing high-reliability fiber optic gyroscope intrinsic frequency by using triple-mode redundancy, comprising three parallel improved DDS modules, a triple-mode redundancy module and a correction module; a threshold value N is preset in the three improved DDS modules, a control frequency word M and a clock signal are received, the control frequency word M is accumulated according to the clock signal, three channels of waveform data are generated respectively according to the comparison result between the accumulated value and the threshold value N, and the three channels of waveform data are output to the triple-mode redundancy module and the correction module; the triple-mode redundancy module performs a logic operation on the three channels of waveform data to obtain output waveform data f out , the output waveform data f out Output to the Y waveguide and correction module; the correction module outputs the waveform data f out , and the consistency of three-way waveform data is judged, and the threshold N in the corresponding improved DDS module is updated. The present invention obtains a highly reliable frequency square wave of the fiber optic gyroscope, and at the same time, the reliability of the digital DDS technology in space applications is increased to the greatest extent through the triple-mode redundant module and the correction module.

Description

Technical Field

[0001] The invention relates to a system and method for realizing high-reliability digital synthesis of fiber optic gyroscope eigenfrequency by utilizing triple-mode redundancy, and belongs to the field of inertial technology. Background Art

[0002] In recent years, the application technology of fiber optic gyroscopes in space has become increasingly mature, and fiber optic gyroscopes have become the preferred product for angle measurement on more and more satellite platforms. In an interferometric fiber optic gyroscope, half of the reciprocal of the difference in the group transmission time of the two optical paths between the Y waveguide and the coupler is called the eigenfrequency of the fiber optic gyroscope. The optical power response of the minimum reciprocity structure of the fiber optic gyroscope is a cosine function. In order to obtain maximum sensitivity, a bias needs to be applied to the Y waveguide to make it work at the zero position of the sine function, while parasitic nonlinearity or amplitude modulation in the Y waveguide may weaken the quality of the bias. In the case of Y waveguide nonlinearity, a simple solution is to make the fiber optic gyroscope work at the eigenfrequency. Therefore, the signal processing device of the fiber optic gyroscope is usually designed based on its eigenfrequency to design its control timing, so improving the accuracy of the fiber optic gyroscope's operating frequency is an important means to improve the performance of the fiber optic gyroscope.

[0003] The digital closed-loop control processor of the fiber optic gyroscope for space use generally uses the anti-fuse chip of ACTEL, which does not have a phase-locked loop. According to the characteristics of the development of aerospace products, the frequency of the crystal oscillator is fixed after the technical status of the product is determined. Since the current domestic fiber optic ring system technology cannot be very precise, it is normal for the length of the fiber optic rings of the same batch to differ by more than ten meters. This leads to a contradiction between the fixed closed-loop frequency of the fiber optic gyroscope for space use and the changing intrinsic frequency of the fiber optic ring. Once the closed-loop frequency of the fiber optic gyroscope differs greatly from the intrinsic frequency (often by several KHz or even more than ten KHz from the intrinsic frequency of the fiber optic ring), the noise of the fiber optic gyroscope will increase, the zero bias of the gyroscope will increase, and the dead zone of the gyroscope will increase. Summary of the invention

[0004] The purpose of the present invention is to overcome the above defects and provide a system and method for realizing high-reliability fiber optic gyroscope intrinsic frequency by using triple-mode redundancy, comprising three parallel improved DDS modules, a triple-mode redundancy module and a correction module; a threshold value N is preset in the three improved DDS modules; the three improved DDS modules receive a control frequency word M with a predetermined value and a clock signal input from the outside, so that the control frequency word M is accumulated according to the clock signal, and three channels of waveform data are generated respectively according to the comparison result between the accumulated value and the threshold value N, and output to the triple-mode redundancy module and the correction module; the triple-mode redundancy module performs a logical operation on the three channels of waveform data input by the three improved DDS modules to obtain output waveform data f out , the output waveform data f outOutput to the Y waveguide and correction module; the correction module is based on the output waveform data f input by the triple-mode redundant module out , and the three-way waveform data input by the three improved DDS modules are judged for consistency, and the threshold N in the corresponding improved DDS module is updated according to the consistency judgment result. The present invention uses triple-mode redundancy to obtain a highly reliable frequency square wave of the fiber optic gyroscope, so that it can work on the intrinsic frequency of the fiber ring; at the same time, the reliability of the digital DDS technology in space applications is increased to the greatest extent through the triple-mode redundancy module and the correction module.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] A system for realizing high-reliability fiber optic gyroscope eigenfrequency by using triple-mode redundancy, comprising three parallel improved DDS modules, a triple-mode redundancy module and a correction module;

[0007] A threshold value N is preset in the three improved DDS modules; the three improved DDS modules receive a control frequency word M with a predetermined value and a clock signal input from the outside, so that the control frequency word M is accumulated according to the clock signal, and three waveform data are generated respectively according to the comparison result between the accumulated value and the threshold value N, and output to the triple-module redundancy module and the correction module;

[0008] The triple-mode redundant module performs logical operations on the three waveform data input by the three improved DDS modules to obtain the output waveform data f out , the output waveform data f out Output to Y waveguide and correction module;

[0009] The correction module is based on the output waveform data f input by the triple-module redundant module. out , and the three waveform data input by the three improved DDS modules are judged for consistency, and the threshold N in the corresponding improved DDS module is updated according to the consistency judgment result.

[0010] Furthermore, the improved DDS module includes a phase accumulator, and the output waveform data consists of basic elements 1 and 0.

[0011] Furthermore, every time a clock signal cycle passes, the control frequency word M is accumulated once in the phase accumulator, and the accumulation is completed once, and the accumulated value is compared with the threshold value N once.

[0012] Furthermore, when the accumulated value obtained by accumulating the control frequency word M according to the clock signal exceeds the threshold value N, the waveform output is inverted; when the accumulated value causes the phase accumulator to overflow, the waveform output is inverted again.

[0013] It can also be understood that the improved DDS module includes a phase accumulator and an implicit waveform data memory, wherein the waveform data memory only needs to store 1 and 0. Assuming that the data width of the phase accumulator is n, when the size of the waveform data memory is 2 n When the accumulated value is less than or equal to the threshold value N, the output is 0; when the accumulated value is greater than the threshold value N and less than or equal to 2, the output is n-1 Output 1 when the accumulated value is greater than 2 n-1 Output 0.

[0014] Furthermore, the control frequency word M and the clock signal fc input to the three improved DDS modules are synchronization signals.

[0015] Furthermore, the method in which the triple-module redundancy module performs a logic operation on the three-channel waveform data input by the three improved DDS modules to obtain output waveform data is a two-out-of-three operation.

[0016] Furthermore, the method in which the triple-module redundancy module performs a logical operation on the three-channel waveform data input by the three improved DDS modules to obtain output waveform data is as follows:

[0017] The three waveform data are Fa, Fb and Fc respectively. The waveform data Fa and the waveform data Fb are operated by logic "AND" to obtain the signal S. The waveform data Fa and the waveform data Fc are operated by logic "AND" to obtain the signal R. The waveform data Fb and the waveform data Fc are operated by logic "AND" to obtain the signal T. The signal R, the signal S and the signal T are operated by logic "OR" to obtain the output waveform data f out .

[0018] Furthermore, the method for the correction module to perform consistency judgment is as follows: the three improved DDS modules are respectively the first improved DDS module, the second improved DDS module and the third improved DDS module, and the three waveform data outputs are respectively Fa, Fb and Fc;

[0019] The output waveform data f out Compare with the waveform data Fa, if they are equal, do not do anything, if they are not equal, use the threshold in the second improved DDS module to update the threshold in the first improved DDS module;

[0020] The output waveform data f out Compare with the waveform data Fb, if they are equal, do nothing, if they are not equal, use the threshold in the third improved DDS module to update the threshold in the second improved DDS module;

[0021] The output waveform data f out Compare with the waveform data Fc, if they are equal, do not do any operation, if they are not equal, use the threshold of the first improved DDS module to update the threshold N in the third improved DDS module.

[0022] Furthermore, the output waveform data f is realized by updating the control frequency word M out Smooth frequency regulation.

[0023] A method for realizing high-reliability fiber optic gyroscope eigenfrequency by using triple mode redundancy is implemented by using the above-mentioned system for realizing high-reliability fiber optic gyroscope eigenfrequency by using triple mode redundancy, and includes the following steps:

[0024] S1 presets a threshold value N in the three improved DDS modules; the three improved DDS modules receive a control frequency word M with a predetermined value and a clock signal input from the outside, so that the control frequency word M is accumulated according to the clock signal, and three waveform data are generated respectively according to the comparison result between the accumulated value and the threshold value N, and output to the triple-module redundancy module and the correction module;

[0025] The S2 triple-module redundant module performs logical operations on the three waveform data input by the three improved DDS modules to obtain the output waveform data f out , the output waveform data f out Output to Y waveguide and correction module;

[0026] The S3 correction module is based on the output waveform data f input by the triple-module redundancy module out , and the three waveform data input by the three improved DDS modules are judged for consistency, and the threshold N in the corresponding improved DDS module is updated according to the consistency judgment result.

[0027] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0028] (1) The present invention innovatively uses triple-mode redundancy to obtain a highly reliable frequency square wave of the fiber optic gyroscope, and realizes the frequency adjustment of the fiber optic gyroscope system, so that it can work at the intrinsic frequency of the fiber optic ring; at the same time, the reliability of digital DDS technology in space applications is increased to the greatest extent through the triple-mode redundancy module and the correction module;

[0029] (2) Aiming at the frequency adjustment requirements of the fiber optic gyro system, the present invention improves the structure of the existing DDS module and introduces a threshold N, so that the DDS module can meet the output of the required waveform while improving the efficiency of waveform generation;

[0030] (3) The present invention designs a correction module, which uses the consistency of the DDS module output waveform to update the threshold of each DDS module in real time, thereby improving the reliability of the data;

[0031] (4) The present invention is beneficial to improving the accuracy of the digital closed-loop frequency of the fiber optic gyroscope, improving the performance of the product, reducing the noise of the fiber optic gyroscope, and reducing the zero bias and dead zone of the fiber optic gyroscope. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the basic structure diagram of DDS in the prior art;

[0033] Figure 2 This is a structural diagram of the improved DDS module of the present invention;

[0034] Figure 3 It is the structural diagram of the improved DDS module and triple-module redundancy module of the present invention;

[0035] Figure 4 It is the basic logic diagram of the triple-module redundancy module of the present invention;

[0036] Figure 5 This is a structural diagram of the triple-module redundancy module and the correction module of the present invention. DETAILED DESCRIPTION

[0037] The following detailed description of the present invention will make the features and advantages of the present invention more clear and explicit.

[0038] The word "exemplary" is used exclusively herein to mean "serving as an example, embodiment, or illustration." Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless otherwise noted.

[0039] Direct digital synthesis (DDS) is a fully digital frequency synthesis technology that has no oscillating elements and phase-locked loops. Instead, it uses a series of data streams through a digital-to-analog converter to generate a pre-set analog signal. It introduces advanced digital signal processing theories and methods into the field of signal synthesis, and achieves the unity between the frequency conversion speed and frequency accuracy of the synthesized signal. It has many advantages, such as continuous phase change, fast frequency conversion speed, extremely high frequency resolution, low phase noise, high frequency stability (depending on the stability of the reference crystal used), and easy control.

[0040] The present invention utilizes DDS technology to synthesize the control frequency of a fiber optic gyroscope and utilizes triple-mode redundancy to improve its algorithm, thereby obtaining a high-reliability digital synthesis technology suitable for use in aerospace products.

[0041] like Figure 2 to Figure 5 The present invention provides a system for realizing high-reliability digital synthesis of fiber optic gyroscope eigenfrequency by using a triple-mode redundant structure with a correction link, which is composed of an improved DDS module, a triple-mode redundant module and a correction module.

[0042] The frequency square wave of the fiber optic gyroscope is generated by the improved DDS module. The three DDS modules have the same structure. The waveform data output by the three DDS modules are input into the three-module redundant module. The waveform correctness is judged in the three-module redundant module, and its output is a highly reliable square wave waveform. The correction module completes the judgment of whether the three-way waveform data output by the three DDS modules are consistent. If there is inconsistency, the DDS module with the error is rewritten or reset.

[0043] The improved DDS module includes a phase accumulator. The control frequency word (M) of the phase accumulator is input and added to the accumulator once every system clock cycle. A threshold N is set. Every time the number in the phase accumulator completes an accumulation, the accumulated value needs to be compared with the threshold N. Once the accumulated value exceeds the threshold N, the waveform output is inverted. Then, when the accumulated value causes the register output to overflow, the waveform output is inverted again. By adjusting the value of the threshold N, a square wave with any duty cycle can be output.

[0044] like Figure 2 The improved DDS module of the present invention is Figure 1 The simplified DDS module is based on the basic DDS module shown in the figure. The core of the basic DDS module is waveform and frequency. Since the output of the improved DDS module is a square wave, its core is only frequency. The simplified DDS module mainly includes a phase accumulator. The input includes a system clock signal and a control frequency word (M). Its waveform data is the basic elements 1 and 0.

[0045] The essence of the DDS module's control over the output waveform frequency is: by changing the frequency control word, the speed of phase accumulation is changed, and thus the speed of reading data in the waveform data memory can be changed, which in essence changes the frequency of the output waveform. Assuming that the data width of the phase accumulator is n and the size of the waveform data memory is 2 n , and the frequency of the system clock is f c , if the frequency control word is M, then when M = 1, the output frequency of the DDS is f out The frequency at which all the data in the waveform data memory is read out is exactly the frequency at which the DDS module outputs the waveform.

[0046] Therefore, the relationship between the DDS module output waveform signal frequency, the frequency control word and the system clock frequency is:

[0047] f out =M×f c / 2 n (0 <M<2 n -1)

[0048] Where: N = 2 n-1

[0049] When the system clock frequency and the data width of the phase accumulator are constant, the output signal frequency of the DDS module is proportional to the frequency control word.

[0050] Embodiment 1:

[0051] The system of this embodiment includes 3 Figure 2 The parallel improved DDS modules shown in the figure have input signals of three DDS modules including control frequency word M and system clock signal fc. These two signals are highly synchronized through the FPGA program. The input control frequency word M and system clock fc of the three modules are synchronized. Figure 3 and Figure 4 The three-module redundant module (i.e., the three-out-of-two module in the figure) uses a three-module redundant algorithm to perform a three-out-of-two design on the waveform data output by the three improved DDSs. The three-module redundant module simultaneously completes the judgment of whether the waveform data output by the three improved DDS modules are consistent. If there is inconsistency, it means that there is a phenomenon that the waveform data of a certain DDS channel is overturned or locked by a single particle in space, and the correction module is used to rewrite or reset the DDS module where the error occurs. The present invention maximizes the reliability of digital DDS technology in space applications through the three-module redundant module and the correction module.

[0052] The waveform data output by the three improved DDS modules are Fa, Fb, and Fc. In the three-module redundant module, the waveform data Fa and the waveform data Fb are operated by logic "AND" to obtain the signal S, the waveform data Fa and the waveform data Fc are operated by logic "AND" to obtain the signal R, the waveform data Fb and the waveform data Fc are operated by logic "AND" to obtain the signal T, and the signals R, S, and T are operated by logic "OR" to obtain the output waveform data f out .

[0053] like Figure 5 The correction module is to output the waveform data f out , respectively compared with the waveform data Fa, Fb, and Fc output by the three improved DDS modules. If they are equal, it means that no threshold N is overturned. If there is an inequality, the corresponding threshold N needs to be updated. The specific method is to output the waveform data f out , and compare it with the waveform data Fa output by DDS module 1. If they are equal, no operation is performed. If they are not equal, the threshold in DDS module 2 needs to be used to update the threshold in DDS module 1. out , and compare it with the waveform data Fb output by DDS module 2. If they are equal, no operation is performed. If they are not equal, the threshold in DDS module 2 needs to be updated with the threshold in DDS module 3. out, and compare it with the waveform data Fc output by DDS module 3. If they are equal, no operation is performed. If they are not equal, the threshold in DDS module 1 needs to be used to update the threshold in DDS module 3.

[0054] The present invention can realize digital synthesis frequency modulation of FPGA and achieve the purpose of smooth frequency modulation by updating the control frequency word.

[0055] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

[0056] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A system for realizing high-reliability fiber optic gyroscope eigenfrequency using triple mode redundancy, characterized in that: It includes three parallel improved DDS modules, a triple-module redundancy module and a correction module; A threshold value N is preset in the three improved DDS modules; the three improved DDS modules receive a control frequency word M with a predetermined value and a clock signal input from the outside, so that the control frequency word M is accumulated according to the clock signal, and three waveform data are generated respectively according to the comparison result between the accumulated value and the threshold value N, and output to the triple-module redundancy module and the correction module; The triple-mode redundant module performs logical operations on the three waveform data input by the three improved DDS modules to obtain the output waveform data f out , the output waveform data f out Output to Y waveguide and correction module; The correction module is based on the output waveform data f input by the triple-module redundant module. out , and the three waveform data input by the three improved DDS modules are subjected to consistency judgment, and the threshold value N in the corresponding improved DDS module is updated according to the consistency judgment result; The improved DDS module includes a phase accumulator, and the output waveform data consists of basic elements 1 and 0; Every time a clock signal cycle passes, the control frequency word M is accumulated once in the phase accumulator, and the accumulation is completed once, and the accumulated value is compared with the threshold value N once; When the accumulated value obtained by accumulating the control frequency word M according to the clock signal exceeds the threshold value N, the waveform output is inverted; when the accumulated value causes the phase accumulator to overflow, the waveform output is inverted again; The method for the correction module to perform consistency judgment is as follows: the three improved DDS modules are respectively the first improved DDS module, the second improved DDS module and the third improved DDS module, and the three waveform data outputs are respectively Fa, Fb and Fc; The output waveform data f out Compare with the waveform data Fa, if they are equal, do not do anything, if they are not equal, use the threshold in the second improved DDS module to update the threshold in the first improved DDS module; The output waveform data f out Compare with the waveform data Fb, if they are equal, do nothing, if they are not equal, use the threshold in the third improved DDS module to update the threshold in the second improved DDS module; The output waveform data f out Compare with the waveform data Fc, if they are equal, do not do any operation, if they are not equal, use the threshold of the first improved DDS module to update the threshold N in the third improved DDS module.

2. The system for realizing high-reliability fiber optic gyroscope eigenfrequency using triple mode redundancy according to claim 1, characterized in that: The control frequency word M and clock signal fc input to the three improved DDS modules are synchronization signals.

3. The system for realizing high-reliability fiber optic gyroscope eigenfrequency using triple mode redundancy according to claim 1, characterized in that: The method in which the triple-module redundancy module performs a logic operation on the three-channel waveform data input by the three improved DDS modules to obtain output waveform data is a three-out-of-two operation.

4. The system for realizing high-reliability fiber optic gyroscope eigenfrequency using triple mode redundancy according to claim 1, characterized in that: The method in which the triple-module redundancy module performs logic operations on the three-channel waveform data input by the three improved DDS modules to obtain output waveform data is as follows: The three waveform data are Fa, Fb and Fc. The waveform data Fa and the waveform data Fb are operated by logic AND to obtain the signal S. The waveform data Fa and the waveform data Fc are operated by logic AND to obtain the signal R. The waveform data Fb and the waveform data Fc are operated by logic AND to obtain the signal T. The signal R, the signal S and the signal T are operated by logic OR to obtain the output waveform data f out .

5. The system for realizing high-reliability fiber optic gyroscope eigenfrequency using triple mode redundancy according to claim 1, characterized in that: By updating the control frequency word M, the output waveform data f is realized out Smooth frequency regulation.

6. A method for realizing high-reliability fiber optic gyroscope eigenfrequency using triple mode redundancy, characterized in that: A system for realizing high-reliability fiber optic gyroscope eigenfrequency by using triple mode redundancy as described in any one of claims 1 to 5 is implemented, comprising the following steps: S1 presets a threshold value N in the three improved DDS modules; the three improved DDS modules receive a control frequency word M with a predetermined value and a clock signal input from the outside, so that the control frequency word M is accumulated according to the clock signal, and three waveform data are generated respectively according to the comparison result between the accumulated value and the threshold value N, and output to the triple-module redundancy module and the correction module; The S2 triple-module redundant module performs logical operations on the three waveform data input by the three improved DDS modules to obtain the output waveform data f out , the output waveform data f out Output to Y waveguide and correction module; The S3 correction module is based on the output waveform data f input by the triple-module redundancy module out , and the three waveform data input by the three improved DDS modules are subjected to consistency judgment, and the threshold value N in the corresponding improved DDS module is updated according to the consistency judgment result; The improved DDS module includes a phase accumulator, and the output waveform data consists of basic elements 1 and 0; Every time a clock signal cycle passes, the control frequency word M is accumulated once in the phase accumulator, and the accumulation is completed once, and the accumulated value is compared with the threshold value N once; When the accumulated value obtained by accumulating the control frequency word M according to the clock signal exceeds the threshold value N, the waveform output is inverted; when the accumulated value causes the phase accumulator to overflow, the waveform output is inverted again; The method for the correction module to perform consistency judgment is as follows: the three improved DDS modules are respectively the first improved DDS module, the second improved DDS module and the third improved DDS module, and the three waveform data outputs are respectively Fa, Fb and Fc; The output waveform data f out Compare with the waveform data Fa, if they are equal, do not do anything, if they are not equal, use the threshold in the second improved DDS module to update the threshold in the first improved DDS module; The output waveform data f out Compare with the waveform data Fb, if they are equal, do nothing, if they are not equal, use the threshold in the third improved DDS module to update the threshold in the second improved DDS module; The output waveform data f out Compare with the waveform data Fc, if they are equal, do not do any operation, if they are not equal, use the threshold of the first improved DDS module to update the threshold N in the third improved DDS module.

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