FPGA-based anti-radiation encoder fault-tolerant system

Abstract

A radiation-resistant encoder fault-tolerant system based on FPGA includes: a rotary transformer, a photoelectric encoder code disk, a photoelectric encoder working hardware circuit, a photoelectric encoder backup hardware circuit, a switching circuit, and an FPGA. The rotary transformer provides a reference for fault diagnosis and circuit switching. The photoelectric encoder code disk is used to measure angle information when the system is working normally. The switching circuit is used to switch to the backup hardware circuit when the working hardware circuit fails. The FPGA determines whether the working hardware circuit is working normally and controls the switching process. The FPGA includes an amplitude adjustment module, a phase compensation module, and an adaptive filtering module. Based on the output of the modules, the FPGA integrates the data and outputs the photoelectric encoder angle information processed by the FPGA. This invention can provide angle signals for motor control systems in radiation environments, improve the long-term reliability of encoder systems in nuclear radiation environments, and has the advantages of small size, low power consumption, and high resolution.

Description

Technical Field

[0001] This invention belongs to the field of nuclear industry technology, specifically relating to a radiation-resistant encoder fault-tolerant system based on FPGA. It utilizes the excellent radiation resistance characteristics of rotary transformers and FPGAs to accurately measure the angular displacement of the motor output shaft in a nuclear radiation environment. Background Technology

[0002] With the annual deployment of nuclear power plants and the rapid development of related nuclear industries, the safety of nuclear power has begun to receive much attention, nuclear emergency rescue equipment and methods have become a research hotspot, and the demand for nuclear emergency response robots is growing.

[0003] An encoder is a sensor that converts mechanical geometric displacement on an output shaft into pulses or digital signals. It is widely used in angle measurement within servo systems, playing a crucial role in servo system control. Currently, rotary transformers in encoders are frequently used in nuclear radiation environments due to their excellent radiation resistance. However, rotary transformers have low resolution, making them unsuitable for high-precision operations such as welding and non-destructive testing in nuclear radiation environments. Photoelectric encoders, as an important member of the encoder family, are widely used in industry due to their high resolution and precision. However, because photoelectric encoders contain many electronic components, the most critical challenge in operating them in nuclear radiation environments is overcoming the radiation damage effects on these components. Electronic components are highly susceptible to the total radiation dose effect in nuclear radiation environments, causing them to malfunction, leading to the paralysis of the entire encoder system and ultimately affecting the entire servo system.

[0004] The accuracy of the angle information output by an encoder system is largely determined by the quality of the grating signal generated by its hardware circuitry. In a radiated environment, the quality of the grating signal is mainly affected by the following factors: DC signal level, amplitude inconsistency, phase non-orthogonality, harmonic components, and noise. While DC signal level can be eliminated through hardware conditioning, the amplitude inconsistency, phase non-orthogonality, harmonic components, and noise interference of sine and cosine signals are difficult to address with high precision through hardware processing alone. Therefore, to ensure the accuracy of the output angle information, the impact of these three adverse factors must be minimized.

[0005] Radiation hardening methods for addressing the total radiation dose effect of existing electronic components can be broadly categorized into three types. The first type focuses on radiation hardening of semiconductor materials, using process modifications to reduce radiation impact by addressing oxide impurities, oxide layer defects, and oxide layer structure. The second type involves comprehensive radiation hardening design at both the circuit layer and layout layer levels of integrated circuits. Since radiation-induced trap charges accumulate in the oxide layer, causing threshold voltage drift and edge leakage current, potential leakage current paths are cut off by modifying the circuit and device layout structure. Both of these types require significant research resources and are extremely costly. The third type, modifying the circuit system structure, is typically used to improve radiation resistance. A common method is to employ redundant circuits to back up vulnerable components. However, due to the high real-time and continuity requirements of encoders, conventional redundant circuits cannot meet these requirements. Furthermore, due to their inherent limitations, conventional redundant circuits result in excessively large overall circuit sizes, unsuitable for applications requiring smaller footprints.

[0006] Therefore, a high-resolution encoder redundancy system with high real-time performance and continuity, and small size is needed. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide an encoder redundancy system that can operate in a nuclear radiation environment. Compared with general encoders, it has the advantages of good real-time performance, long life, simple structure, small size, low power consumption and high resolution.

[0008] This invention designs a radiation-resistant encoder fault-tolerant system based on FPGA, comprising: a rotary transformer, a photoelectric encoder code disk, a photoelectric encoder working hardware circuit, a photoelectric encoder backup hardware circuit, a switching circuit, and an FPGA. The rotary transformer provides a reference for fault diagnosis and circuit switching. The photoelectric encoder code disk is used to measure angle information when the system is working normally. The rotary transformer and the photoelectric encoder code disk are mounted together on the same rotating shaft under test and rotate together with the shaft, converting the angle information of the shaft rotation into electrical signals and transmitting them separately. The switching circuit is used to switch to the photoelectric encoder backup hardware circuit when the photoelectric encoder working hardware circuit fails. The FPGA determines whether the photoelectric encoder working hardware circuit is working normally and controls the switching process. The angle information measured by the rotary transformer is output to the FPGA, and the grating signal subdivided by the photoelectric encoder working hardware circuit is also output to the FPGA. The FPGA includes an amplitude adjustment module, a phase compensation module, and an adaptive filtering module. Based on the outputs of the amplitude adjustment module, the phase compensation module, and the adaptive filtering module, the FPGA integrates the data and outputs the photoelectric encoder angle information processed by the FPGA.

[0009] Furthermore, the photoelectric encoder's operating hardware circuit consists of a photoelectric sensing module, a differential amplification module, a coarse code subdivision module, and a fine code module. The input of the photoelectric sensing module comes from the photoelectric encoder's code disk module, which converts the optical signal containing angle information into an electrical signal. After passing through the differential amplification module, it generates an electrical signal with a high signal-to-noise ratio, which is then input to the coarse code subdivision module and the fine code module. The coarse code subdivision module and the fine code module further subdivide the electrical signal containing angle information and output them to the FPGA for superposition processing to obtain angle information with higher resolution. The photoelectric encoder backup hardware circuit adopts a cold backup without power-on, and its specific circuit is the same as that of the photoelectric encoder's operating hardware circuit.

[0010] Furthermore, the switching circuit employs a multiplexer and performs switching control under the control of the FPGA. When the working hardware circuit module of the photoelectric encoder fails, the switching circuit switches to the backup hardware circuit module of the photoelectric encoder.

[0011] Furthermore, the amplitude adjustment module is used to handle unequal amplitudes of sine and cosine signals. The FPGA samples the sine and cosine amplitudes of the photoelectric encoder respectively. When the two are equal, the amplitude at this moment is output and stored, overwriting the previous stored value. Otherwise, the stored previous sine and cosine amplitude is assigned to the current value and output, and the previously stored sine and cosine amplitude is retained. This process is repeated to eliminate the influence of unequal amplitudes of sine and cosine signals.

[0012] Furthermore, the phase compensation module is used to handle phase non-orthogonality, performing phase compensation on sine and cosine grating signals input to the FPGA that do not satisfy phase orthogonality. The FPGA samples the sine and cosine signals of the photoelectric encoder. When the sampled values ​​of the two signals are equal and greater than 0 at the same moment, the sampled value at this moment is recorded, and the phase Ф0 of the cosine signal of the photoelectric encoder at the current moment is calculated using this sampled value. This is used as a reference value for the cosine phase at the first intersection point of the two signals within the same period. Subsequently, each time the FPGA detects that the sampled values ​​of the sine and cosine signals at the same moment are equal and greater than 0, it calculates the cosine phase Ф0 using the sampled value at this moment. i Determine Ф i If the expression is equal to Ф0, no compensation is needed; otherwise, calculate |Ф0 - Ф0. i The obtained value is the phase compensation for this period. The compensation value of the cosine signal sample value for this period is calculated using this value, and the cosine signal sample value for this period is corrected to complete the phase compensation.

[0013] Furthermore, the adaptive filtering module is used to eliminate harmonic components and handle noise. It receives the output of the phase compensation module as a fine code, uses the value calculated from the rotary transformer output as the initial weight of the integrated data, and superimposes it with the coarse code input to the FPGA to calculate the photoelectric encoder angle output. The angle information output by the rotary transformer and the angle output of the photoelectric encoder are subtracted and the error is calculated. The step size is continuously adjusted based on the magnitude of the error. The weight of the integrated data is updated with the adjusted step size, and the angle output of the photoelectric encoder is calculated again with the updated weight, so that the angle output of the photoelectric encoder gradually approaches the output of the rotary transformer, thereby outputting the final photoelectric encoder angle information processed by the FPGA.

[0014] Furthermore, when the angle information of the photoelectric encoder processed by the FPGA is approximately the same as the angle information output by the rotary transformer, it indicates that the photoelectric encoder is working normally and outputs the angle information of the photoelectric encoder processed by the FPGA; if the angle information of the photoelectric encoder processed by the FPGA differs too much from the angle information output by the rotary transformer, it indicates that the working hardware circuit of the photoelectric encoder has failed in the radiation environment. The FPGA stores the angle information output by the rotary transformer and controls the switching circuit to work, so that the working hardware circuit of the photoelectric encoder is powered off and does not work, and the photoelectric encoder backup hardware circuit is powered on and works.

[0015] In this invention, the encoder system solves the problem of low resolution of rotary transformers commonly used in radiation environments, making the encoder redundancy system suitable for more precise applications. Unlike commonly used triple-mode redundancy systems which are bulky, this encoder redundancy system is small in size and, due to the use of cold backup, has excellent radiation resistance, making it suitable for applications in nuclear radiation environments where small size is a critical requirement.

[0016] This system enhances its reliability through a combination of hardware redundancy and software fault tolerance. The software fault tolerance component addresses interference factors affecting encoder signal quality by incorporating amplitude adjustment, quadrature error compensation, and adaptive filtering modules. This ensures the encoder system maintains high accuracy over extended periods in irradiated environments. These two measures significantly improve the encoder system's real-time performance. While software fault tolerance enhances the encoder system's radiation resistance, its effectiveness decreases as the total system radiation dose increases. When the difference between the photoelectric encoder output D1 and the angle information D2 output by the rotary transformer exceeds the allowable range, a switching circuit is required to switch to the photoelectric encoder backup hardware circuit module. After switching, the software fault tolerance component can continue to be used, further extending the encoder system's lifespan.

[0017] Compared with existing technologies, the redundancy mode of this invention is dual-mode redundancy and cold backup, which results in a smaller size and lower power consumption while ensuring high reliability. Compared with the rotary transformers commonly used in radiation environments, it has higher resolution and is more suitable for precision operations in strong radiation environments. Attached Figure Description

[0018] Figure 1 Hardware architecture diagram of the present invention;

[0019] Figure 2 Flowchart of the amplitude adjustment module of this invention;

[0020] Figure 3 Flowchart of the phase compensation module of this invention;

[0021] Figure 4 Schematic diagram of the adaptive filtering principle of this invention;

[0022] Figure 5 Flowchart of the adaptive filtering module of this invention;

[0023] Figure 6 Fault-tolerant flowcharts of the amplitude adjustment module, phase compensation module, and adaptive filtering module in the FPGA of this invention;

[0024] Figure 7 The control flowchart of this invention. Detailed Implementation

[0025] The technical solution of the present invention will be specifically described below with reference to the embodiments.

[0026] Figure 1 As shown, the hardware of this redundant system consists of six parts: a rotary transformer, a photoelectric encoder code disk, a photoelectric encoder working hardware circuit, a photoelectric encoder backup hardware circuit, a switching circuit, and an FPGA.

[0027] The photoelectric encoder code disk and its operating hardware circuitry constitute the normal working part of the radiation-resistant encoder fault-tolerant system. They operate under tolerable radiation doses, outputting angle information to the outside world. The rotary transformer and the photoelectric encoder code disk are mounted together on the same rotating shaft under test. Both are powered on. Initially, the photoelectric encoder's operating hardware circuitry is powered on, while its backup hardware circuitry is not. Both rotate with the shaft under test, converting the shaft's rotation angle information into electrical signals and transmitting them separately. Because they rotate with the same shaft, their output angle information is the same. However, due to the different principles they use to convert angle information into electrical signals, the resolution of their output angle information differs.

[0028] The photoelectric encoder code disk is used to measure angle information when the system is working normally. The rotary transformer is always in working condition, providing a reference for fault diagnosis and circuit switching. The photoelectric encoder backup hardware circuit is a redundant module of the photoelectric encoder working hardware circuit. When a fault is detected in the working hardware circuit, the system switches to this backup hardware circuit. The switching circuit can switch to the redundant backup hardware circuit when the working hardware circuit fails. The FPGA is used to determine whether the working hardware circuit is working normally and to control the switching process.

[0029] The angle information D2 measured by the rotary transformer is output to the FPGA, and the grating signal after being subdivided by the photoelectric encoder's working hardware circuit is also output to the FPGA.

[0030] The hardware circuit of the photoelectric encoder consists of a photoelectric sensing module, a differential amplifier module, a coarse code subdivision module, and a fine code module. The photoelectric sensing module receives input from the encoder's code disk module and converts the optical signal containing angle information into an electrical signal. Since this initial electrical signal is very small and contains a lot of noise, which is detrimental to subsequent processing, the differential amplifier module generates an electrical signal with a higher signal-to-noise ratio. This generated electrical signal is then input to the coarse code subdivision module and the fine code module, with the fine code module consisting of an AD converter. The coarse and fine code modules further subdivide the electrical signal containing angle information and output them to the FPGA for superposition processing, ultimately obtaining high-resolution angle information.

[0031] The backup hardware circuit of the photoelectric encoder is identical to the working hardware circuit of the photoelectric encoder. However, it employs a cold backup method that does not require power-on, offering stronger radiation resistance compared to a hot backup. During normal operation, the working hardware circuit module of the photoelectric encoder is used. When the system detects a failure in this module, it switches to the backup hardware circuit module, thereby extending the lifespan of the encoder system.

[0032] The switching circuit is designed with the participation of a multiplexer and performs switching control under the control of the FPGA. When the working hardware circuit module of the photoelectric encoder fails, the switching circuit switches to the backup hardware circuit module of the photoelectric encoder.

[0033] Field-programmable gate arrays (FPGAs) offer excellent radiation resistance and high operating speed. In radiation-hardened encoder fault-tolerant systems, this component primarily plays the following roles:

[0034] 1. The software fault-tolerant module is used to compensate the grating signal input to the FPGA, thereby improving the accuracy of the encoder's output angle information in radiation without switching hardware circuit modules, and further extending the lifespan of the encoder system.

[0035] 2. Integrate the data from the coarse code module and the fine code module of the photoelectric encoder to generate high-resolution angle information;

[0036] 3. The angle signal output from the rotary transformer is input into the FPGA and compared with the angle information detected by the photoelectric encoder. Since both encoders acquire angle information from the same rotating shaft, if the difference between the two data is within an acceptable range, the photoelectric encoder is considered to be working normally (the rotary transformer has excellent radiation resistance and can be considered unaffected by radiation). If the difference between the two data is large, the photoelectric encoder is considered to have failed in the radiation environment. In this case, the FPGA uses the rotary transformer as a temporary working encoder, saves its angle information, and controls the switching circuit module to switch to the photoelectric encoder backup hardware circuit module. After the switch is completed, the FPGA uses the angle information output by the rotary transformer at this moment as the starting angle of the photoelectric encoder after the switch, so that the encoder system continues to work at high resolution.

[0037] During normal operation, the rotary transformer and photoelectric encoder work together, but the system output angle information is only the angle measured by the photoelectric encoder. The angle information output by the rotary transformer is only used to provide the correct angle reference for the software fault-tolerant module and to verify whether the photoelectric encoder is working properly. When a photoelectric encoder failure is detected, the FPGA switches to the photoelectric encoder backup hardware circuit module. During the switching process, the angle information measured by the rotary transformer is output and stored. When the switching is complete, the angle information measured by the photoelectric encoder continues to be used as the system output.

[0038] The software fault-tolerant module addresses three major factors affecting the quality of photoelectric encoder grating signals that are difficult to eliminate through hardware processing in radiated environments: unequal amplitudes of sine and cosine signals, phase non-orthogonality, and harmonic components and noise. It designs three fault-tolerant methods that can operate in an FPGA environment, including an amplitude adjustment module, a phase compensation module, and an adaptive filtering module. Among these, the amplitude adjustment module solves the problem of unequal amplitudes of sine and cosine signals, such as... Figure 2As shown, the FPGA samples the sine and cosine amplitudes of the photoelectric encoder (the output of the differential amplifier module in the photoelectric encoder's hardware circuit). When the two amplitudes are equal, the current amplitude is output and stored, overwriting the previous stored value. Otherwise, the previously stored sine and cosine amplitudes are assigned to the current output value, and the previously stored sine and cosine amplitudes are retained. This process is repeated to eliminate the influence of unequal sine and cosine signal amplitudes. The phase compensation module designs a corresponding phase compensation algorithm to address the influencing factor of phase non-orthogonality and implements it in the FPGA. It performs phase compensation for sine and cosine grating signals input to the FPGA that do not satisfy phase orthogonality. When the system starts working, the FPGA samples the sine and cosine signals of the photoelectric encoder. When the two sampled values ​​are equal and greater than 0 at the same moment, i.e., at the first intersection point within one cycle of the sine and cosine signals, the sampled value at this moment is recorded. The phase Ф0 of the photoelectric encoder's cosine signal at the current moment is calculated using this sampled value, which serves as a reference value for the cosine phase at the first intersection point within the same cycle of the two signals. Subsequently, whenever the FPGA detects that the sine and cosine signal sample values ​​are equal and greater than 0 at the same time, it calculates the cosine phase Ф based on the sample values ​​at that moment. i Determine Ф i If |Ф0 - Ф0| is equal to |Ф0|, then the phases are orthogonal and no compensation is needed; otherwise, calculate |Ф0 - Ф0|. i The obtained value is the phase compensation for this period. The compensation value of the cosine signal sample value for this period is calculated using this value, thereby correcting the cosine signal sample value for this period and achieving the purpose of phase compensation.

[0039] The adaptive filtering module is designed to eliminate the effects of harmonic components and noise, such as... Figure 4 As shown. The output x of the phase compensation module is fed to the FPGA for data integration. The integration process is as follows: the output x of the phase compensation module is used as the fine code and superimposed with the coarse code input to the FPGA to generate the photoelectric encoder angle output y (the overall output of the photoelectric encoder, the angle information after processing by the photoelectric encoder code disk, photoelectric encoder hardware circuit, and FPGA). However, due to the presence of harmonic components and noise, the output angle information y and the angle information D2 output by the rotary transformer are not close, and the difference increases with the time the encoder system is exposed to radiation. However, this problem can be solved by an adaptive filtering algorithm. The difference e between the angle information D2 output by the rotary transformer and the encoder angle output y is input into the adaptive filtering algorithm, thereby continuously adjusting the weights of the FPGA integrated data, eventually making y gradually approach D2, thus outputting angle information D1, which to a certain extent eliminates the influence of harmonic components and noise. The adaptive algorithm is as follows. Figure 5As shown, to improve the real-time performance of the system, the output of the rotary transformer is imported into the algorithm. Using this as a basis, the initial weights of the algorithm are calculated in the FPGA, avoiding iterations from zero and significantly shortening the algorithm's convergence time. Furthermore, the algorithm's step size changes with the error e. At the beginning of the iteration, the error e is large, so the algorithm's step size is increased to improve convergence speed. As iterations progress, the difference e continuously decreases, and to improve output stability, the algorithm's step size is continuously decreased. This method of changing the algorithm's step size with the error significantly improves the algorithm's convergence speed and maintains high stability. The specific steps of this adaptive algorithm are as follows: 1. Use the output x of the phase compensation module as the input to the adaptive filtering algorithm, and use the value calculated from the rotary transformer output as the initial weight W0 of the integrated data. Combined with the coarse code value, calculate the encoder angle output y. 2. Calculate the difference between the angle information D2 output by the rotary transformer and the encoder angle output y, resulting in the error e. 3. Continuously adjust the algorithm's step size based on the magnitude of the error e. 4. Update the weights of the integrated data with the adjusted step size, and then calculate the encoder angle output y with the updated weights. After multiple cycles, the encoder angle output y gradually approaches the output D2 of the rotary transformer, thus outputting angle information D1.

[0040] These two measures greatly improve the real-time performance of the encoder system. Although software fault tolerance enhances the encoder system's radiation resistance, its radiation resistance continuously deteriorates as the total radiation dose of the system increases. When the difference between the photoelectric encoder output D1 and the angle information D2 output by the rotary transformer exceeds the allowable range, it is still necessary to use a switching circuit to switch to the photoelectric encoder backup hardware circuit module. After the switch is completed, the software fault-tolerant part can continue to be used, further improving the lifespan of the encoder system.

[0041] The overall flowchart of the software fault tolerance module is as follows: Figure 6 As shown in the diagram, in the FPGA, the grating signal is sequentially processed through an amplitude adjustment module, a phase compensation algorithm module, and an adaptive filtering algorithm-controlled integrated data module to obtain D1. (The diagram shows the process in the FPGA.) Figure 7As shown, inside the FPGA, the values ​​of D1 and D2 are compared. If they are similar, it indicates that the photoelectric encoder is working normally (the photoelectric encoder as a whole includes the encoder code disk, the encoder hardware circuit, and the FPGA), and the FPGA outputs the encoder angle information D1. If D1 and D2 differ significantly (the specific difference can be determined by the actual accuracy), it indicates that the encoder hardware circuit (operating) has failed in the radiation environment. At this time, the FPGA stores the rotary transformer output angle information D2 and simultaneously controls the switching circuit (multiplexer) to operate, causing the encoder operating hardware circuit to power down and stop working, while powering on the backup hardware circuit. During the switching process, the FPGA outputs the rotary transformer output angle information D2. When the FPGA detects that the switching is complete, it outputs the rotary transformer's current output angle information D2. i The initial angle value of the photoelectric encoder is used to calculate and output the output angle information. If the FPGA detects that the switching is not complete, it continues the switching process. This completes the encoder system redundancy and increases the system's lifespan.

[0042] This invention utilizes the excellent radiation resistance of rotary transformers and FPGAs. The rotary transformer serves as a standard for determining whether the hardware circuitry of a high-resolution photoelectric encoder has failed, thus determining whether to switch to a cold backup circuit. Furthermore, the rotary transformer can temporarily act as the working encoder during switching processes, avoiding the inability to monitor angles during switching and preventing inaccurate output angles from the photoelectric encoder after switching. In addition, the output angle information of the rotary encoder also serves as a reference for the adaptive filtering algorithm, making the angle information D1 output by the incremental encoder more accurate. The high speed and strong radiation resistance of FPGAs are well-suited for controlling encoder redundancy systems in radiant environments, offering advantages such as high reliability and good real-time performance. Those skilled in the art can select electronic components with good radiation resistance, thereby extending the lifespan of the encoder redundancy system.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. An FPGA-based radiation tolerant encoder fault-tolerant system, comprising: The rotating transformer, the photoelectric encoder code disc, the photoelectric encoder working hardware circuit, the photoelectric encoder backup hardware circuit, the switching circuit and the FPGA, the rotating transformer provides a reference for fault diagnosis and circuit switching, the photoelectric encoder code disc is used for measuring angle information when the system works normally, the rotating transformer and the photoelectric encoder code disc are installed on the same rotating shaft to be measured and rotate with the rotating shaft to be measured, the angle information of the shaft rotation is converted into electrical signals and transmitted out respectively, the switching circuit is used for switching to the photoelectric encoder backup hardware circuit when the photoelectric encoder working hardware circuit fails, the FPGA judges whether the photoelectric encoder working hardware circuit works normally and controls the switching process, the angle information measured by the rotating transformer is output to the FPGA, and the grating signal after being subdivided by the photoelectric encoder working hardware circuit is also output to the FPGA, the FPGA includes an amplitude adjustment module, a phase compensation module and an adaptive filtering module, FPGA integrated data is calculated according to the output of the amplitude adjustment module, the phase compensation module and the adaptive filtering module, and the photoelectric encoder angle information processed by the FPGA is output; the photoelectric encoder backup hardware circuit adopts a cold backup without power supply, and the specific circuit is the same as that of the photoelectric encoder working hardware circuit; the amplitude adjustment module is used for processing the unequal amplitudes of the sine and cosine signals, the FPGA samples the amplitudes of the photoelectric encoder sine and cosine signals respectively, when the amplitudes are equal, the amplitude at this moment is output and stored, the previous stored value is covered, otherwise the previous stored sine and cosine amplitudes are assigned to the current value output, and the previous stored sine and cosine amplitudes are retained, the process is repeated to eliminate the influence of unequal amplitudes of the sine and cosine signals; the phase compensation module is used for processing the non-orthogonal phase, and the phase compensation is performed on the non-orthogonal phase sine and cosine grating signals input into the FPGA; the FPGA samples the photoelectric encoder sine and cosine signals, when the sampling values of the two signals are equal and greater than 0 at the same time, the sampling value at this moment is recorded, and the phase Ф0 of the photoelectric encoder cosine signal at the current moment is calculated through the sampling value, which is used as the reference value of the cosine phase at the first intersection point in the same period of the subsequent two signals, and the FPGA detects the sampling values of the sine and cosine signals at the same time every time, when the sampling values of the two signals are equal and greater than 0, the cosine phase Ф i is calculated through the sampling value at this moment, and whether Ф i is equal to Ф0 is judged, if equal, no compensation is needed, otherwise, |Ф i The value obtained is the phase compensation of the period, and the compensation value of the cosine signal sample value of the period is calculated through the value, the cosine signal sample value of the period is corrected, and the phase compensation is completed; the adaptive filtering module is used for eliminating harmonic components and noise processing, receives the output of the phase compensation module as the fine code, takes the value calculated by the resolver output as the initial weight of the integrated data, superimposes the coarse code input into the FPGA, and calculates the photoelectric encoder angle output; the angle information of the resolver output and the photoelectric encoder angle output are subtracted and the error is calculated, and the step size is adjusted according to the size of the error. The weight of the integrated data is updated with the adjusted step, and the photoelectric encoder angle output is calculated with the updated weight, so that the photoelectric encoder angle output gradually approaches the resolver output, thereby outputting the final FPGA-processed photoelectric encoder angle information.

2. The system of claim 1, wherein, The photoelectric encoder working hardware circuit is composed of a photoelectric sensing module, a differential amplification module, a coarse code four subdivision module and a fine code module. The input of the photoelectric sensing module comes from the photoelectric encoder disc module, and the optical signal containing angle information is converted into an electrical signal. The signal-to-noise ratio of the electrical signal is large after the differential amplification module, and the electrical signal is input to the coarse code four subdivision module and the fine code module. The coarse code four subdivision module and the fine code module subdivide the electrical signal containing angle information, and output the electrical signal to the FPGA for superposition processing to obtain angle information with high resolution.

3. The system of claim 1, wherein, The switching circuit adopts a multiplexer, and switching control is performed under the control of the FPGA. When the photoelectric encoder working hardware circuit module fails, the switching circuit is switched to the photoelectric encoder backup hardware circuit module.

4. The system of claim 1, wherein when the FPGA-processed photoelectric encoder angle information is approximately equal to the angle information of the resolver output, it indicates that the photoelectric encoder is working normally, and the FPGA-processed photoelectric encoder angle information is output; when the FPGA-processed photoelectric encoder angle information is too different from the angle information of the resolver output, it indicates that the photoelectric encoder working hardware circuit fails in the radiation environment, the FPGA stores the resolver output angle information, controls the switching circuit to work, and makes the photoelectric encoder working hardware circuit power off and not work, so that the photoelectric encoder backup hardware circuit is powered on and works.

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