Design method of dual-phase laser gyroscope

Abstract

The invention discloses a design method of a two-phase laser gyroscope, and belongs to the technical field of laser gyroscope manufacturing. According to the design method, under the condition of ensuring the same jitter frequency and jitter amplitude, the upper and lower gyroscope cavities realize jitter with the same frequency and stable phase difference, and the two balancing weights with the same mass and the same form reversely jitter relative to the gyroscope, so that the overall working stability of the two-phase gyroscope is ensured. Besides, by demodulating four paths of A / B signals, the outputs of the areas outside the lock area are acquired in a crossed manner and spliced into an output without a lock area, so that an unlocking function is realized, and the accuracy and the stability of the laser gyroscope are improved. Meanwhile, a working inertia combination and a backup inertia combination can be fused, and the size, the weight and the cost are greatly reduced.

Description

Technical Field

[0001] The invention relates to a design method of a dual-phase laser gyroscope, and belongs to the technical field of laser gyroscope manufacturing. Background Art

[0002] The laser gyroscope is different from the traditional mechanical gyroscope. It is composed of a closed quadrilateral or triangular resonant cavity. The gyroscope cavity is equipped with an output reflector, a control reflector, and a deflection reflector. The helium-neon laser forms a closed loop through the reflector. The beam splitter will split a laser beam into two laser beams propagating in the forward and reverse directions. When the object moves and produces angular displacement, the two laser beams will meet and produce interference, which can be used to calculate the angular velocity of the object. Its accuracy is much higher than that of a mechanical gyroscope. Since the laser gyroscope has no moving parts, it is easy to maintain, has high reliability, and has a long service life, so it has become a core component in the inertial reference system.

[0003] The lock zone of the laser gyroscope is the key to limiting the working accuracy of the gyroscope. The lock zone essentially refers to the state where the pulse output of the gyroscope at low speed cannot meet the pulse counting analysis requirements due to reasons such as non-uniform loss of the gyroscope. In this state, the sensitivity and accuracy of the gyroscope will be negatively affected. The key to solving the problem of laser gyroscope lock is jitter. The jitter function can subdivide the gyroscope lock zone into multiple small lock zones, and optimize the divided small lock zones by injecting noise.

[0004] At present, the jitter control of laser gyroscopes is mainly based on white noise sine waves and high and low periodic square waves. The white noise sine wave jitter method is one of the more mature jitter methods in the development of laser gyroscopes. This method is a fixed-frequency sine wave, which is multiplied by a white noise with the same frequency as the jitter frequency through a multiplier, and then the laser gyroscope is jittered through proportional amplification and power amplifier circuits. However, after FFT analysis, it can be seen that although the noise spectrum is relatively rich, the high-frequency and low-frequency response amplitudes of the gyroscope's non-resonance point are large, and the response amplitudes are large at odd and even times of frequency, which has a negative impact on the gyroscope when it works at the resonant point. At the same time, the high-frequency noise response amplitude between odd and even times of frequency is also relatively large, which will lead to a reduction in the noise injection effect. The high and low periodic square wave jitter method can be synthesized using direct digital frequency synthesis or obtained by multiplying a square wave with the same frequency as the jitter frequency and a low-frequency periodic square wave. However, this type of jittering method has a relatively simple noise injection, the noise near the jittering frequency is not rich enough, and the feedback amplitude of the odd-order multiples of the jittering frequency is large, which will introduce high-frequency noise and have a negative impact on the jittering noise injection. It has a certain negative impact on the noise injection effect and the unlocking effect of the laser gyroscope. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the prior art, a design method for a dual-phase laser gyroscope is proposed, and the A / B signal outputs of the laser gyroscope are combined and demodulated through an orthogonal dithering method with the same dithering frequency, so as to completely eliminate the existence of the lock area and improve the test accuracy and test sensitivity of the laser gyroscope.

[0006] The technical solution of the present invention is:

[0007] A design method for a dual-phase laser gyroscope, comprising:

[0008] Step 1: Process two symmetrical glass-ceramic cavities;

[0009] Step 2: Bond the dual-phase shaking wheel to two glass-ceramic cavities to form an upper and lower gyroscope; and provide a counterweight block with a shaking wheel for each of the upper and lower gyroscopes;

[0010] Step 3: The shaking board generates four shaking driving signals with the same frequency and phase difference and loads them on four shaking wheels, so that the upper and lower gyroscopes shake orthogonally and the two counterweights shake in the opposite direction relative to the gyroscope on the same side;

[0011] Step 4: Establish a four-channel A / B signal demodulation system with orthogonal jitter, receive the four-channel photoelectric signals output by the upper and lower gyroscopes, obtain the overlock steering information, intercept the time period information of the upper and lower gyroscopes without overlock steering, splice and output.

[0012] Furthermore, in step 2, four shaking wheels are processed by using indium steel material; the mounting holes of the four shaking wheels are processed by a through-type method; a group of piezoelectric ceramic sheets are bonded to the blades of each shaking wheel, including a driving ceramic sheet and a feedback ceramic sheet, and a total of three wires are led out, namely a driving line, a ground line, and a feedback line;

[0013] The two shaking wheels are bonded to two glass-ceramic cavities to form an upper gyroscope and a lower gyroscope.

[0014] The other two shaking wheels are respectively connected to two counterweights. The counterweight connected to the upper gyroscope is called an upper counterweight, and the counterweight connected to the lower gyroscope is called a lower counterweight.

[0015] Furthermore, in step 2, the piezoelectric ceramic sheets bonded to the blades of each shaking wheel have the same dielectric constant, and the total capacitance value of the driving ceramic sheets is the same.

[0016] Furthermore, the dither board outputs two drive control signals through DDS mode. One signal is phase-shifted by 90° and then passes through the same noise multiplier as the other signal to achieve phase shifting and noise injection of the drive control signal. The signal is then amplified through a power amplifier circuit to obtain a dither drive signal with the same dither frequency and a 90° phase difference. The signal is loaded on the upper and lower gyro dither wheels. The feedback signals of the upper and lower dither wheels also produce a 90° phase difference to achieve orthogonal dithering and closed-loop control of the upper and lower gyroscopes.

[0017] Furthermore, the two obtained shaking driving signals are phase-shifted by 180° and loaded on the shaking wheels of the two counterweights respectively, so that the counterweights can shake in opposite directions relative to the gyroscopes on the same side, thereby eliminating the influence of resonance.

[0018] Furthermore, a four-way signal demodulation system with orthogonal jitter is established to process:

[0019] Receiving two AC photoelectric signals output by the upper gyro and two AC photoelectric signals output by the lower gyro, and demodulating them respectively to obtain the overlock steering information of the upper and lower gyros;

[0020] The time periods of the upper and lower gyroscopes without overlock steering are intercepted, and within each time period, the difference frequency calculation is performed on the two signals output within each time period; the calculated signals are spliced ​​and then output.

[0021] Furthermore, during the operation of the inertial group, the gyroscope has a high-precision mode and a backup mode; under normal circumstances, the high-precision mode is adopted, that is, the dual gyroscopes work together; when a gyroscope has a problem and cannot work normally, it automatically switches to a single gyroscope.

[0022] Furthermore, the driving frequency of the upper shaking wheel is consistent with the natural frequency of the shaking wheel, generating resonance, causing the upper gyroscope to shake out of lock; the driving frequency of the lower shaking wheel with a phase difference is consistent with the natural frequency of the shaking wheel, generating resonance, causing the lower gyroscope to shake out of lock.

[0023] Furthermore, in step 1, the method for processing two symmetrical glass-ceramic cavities is:

[0024] Divide the rectangular glass-ceramic block into two gyroscope-sized pieces;

[0025] Cut two glass-ceramic cavities, align them side by side, and use a cutter to drill holes longitudinally in the center of the two parallel and aligned glass-ceramic cavities to form a unified shaking wheel bonding surface;

[0026] Drill two transverse and longitudinal capillaries of glass-ceramics using parallel tools;

[0027] The cathodes of two microcrystalline glass cavities are placed symmetrically and aligned outward, the cathodes are processed with symmetrical tooling, and then the positive electrode extraction and general positive electrode processing are performed to obtain two symmetrical microcrystalline glass cavities.

[0028] Furthermore, the material of the counterweight block is microcrystalline glass, and a hole is drilled longitudinally in the cavity of the counterweight block to form a bonding surface for the shaking wheel; after installation, the hole of the counterweight block is coaxial with the holes of the upper and lower gyroscopes.

[0029] The advantages of the present invention compared with the prior art are:

[0030] (1) The effect achieved by the feature of step 1 of the present invention is that the upper and lower parts of the laser gyroscope have better coaxiality of the shaking wheel installation, and the cathode and anode capillary lengths are more symmetrical, thereby ensuring that the output pulse difference of the upper and lower gyroscopes under the same shaking intensity is small. At the same time, a simple symmetrical processing method is provided, which lays the foundation for the subsequent bonding of the shaking wheel and the combined demodulation of the two gyroscopes.

[0031] (2) The effect achieved by the feature of step 2 of the present invention is to provide a design scheme for the core components of the dual-phase gyroscope, so that the upper and lower gyroscope cavities can achieve the same frequency and stable phase difference of the jitter while ensuring the same jitter frequency and jitter amplitude, and at the same time make the energy acting on the two cavities close to the same, and the frequency of the AC signal output by the two cavities is close to the same under the same energy. In addition, ensuring the consistency of parameters such as the dielectric constant and capacitance value of the ceramic can make the gyroscope have better adaptability, thereby providing strong support for the subsequent demodulation of the A / B signal and improving the sensitivity and accuracy of the gyroscope. It is also worth noting that if the dual-phase jitter wheel is designed as an integral jitter wheel, then the jitter frequency, that is, its own resonant frequency point, has good consistency. At the same time, although the upper and lower jitter frequencies are the same frequency, the reverse jitter of the counterweight blocks of equal mass and shape can make the total resonance energy of the entire jitter system approximately zero, thereby greatly eliminating the negative impact of resonance and ensuring the overall working stability of the dual-phase gyroscope. In the inertial combination composed of general gyroscopes, reverse counterweight operation can also be performed to try to eliminate the negative impact of resonance.

[0032] (3) The effect achieved by the third and fourth features of the present invention is the core demodulation step of the dual-phase laser gyroscope, which provides a guarantee for improving sensitivity and test accuracy. The demodulation of ordinary laser gyroscopes generally uses two A / B signals with a phase difference of 90° for phase detection demodulation and determination of the rotation direction. It is difficult to avoid the dynamic lock zone caused by the jitter steering, and can only be continuously divided and reduced by injecting noise and increasing the jitter amplitude. The dual-phase laser gyroscope can use the upper and lower gyroscopes with jitter phase difference to demodulate the relationship between the four A / B signals, and the output of the area outside the lock zone is spliced ​​into a gyroscope output without a lock zone to achieve the function of the laser gyroscope without a lock zone. In addition, when testing angular velocity, ordinary laser gyroscopes often cause part of the real data to be lost due to passing the lock zone. Even if the gyroscope with a high jitter frequency can greatly reduce the single-cycle lock zone time, it still cannot avoid the loss of sudden angular velocity information, which will have a certain negative impact on the test sensitivity and accuracy. This method provides a high-sensitivity and high-precision working solution through the cooperative demodulation of two gyroscopes with the same jitter frequency. Since the jitter wheels with the same jitter frequency will have a resonance effect even if there is a phase difference, the mechanical resonance formula can be approximately referred to: Vibration sine formula: The formula for a single degree of freedom system under simple harmonic force: In view of the fact that the resonance of the inertial combination of the three-axis laser gyroscope in different directions will affect the initial jitter and navigation of the gyroscope, three systems can be briefly established for the dual-phase laser gyroscope to analyze the resonance effect. The driving frequency of the upper jitter wheel is consistent with the natural frequency of the jitter wheel to produce resonance, which makes the upper gyroscope jitter out of lock, which can be simplified as resonance system one; the driving frequency of the lower jitter wheel with a phase difference is consistent with the natural frequency of the jitter wheel to produce resonance, which makes the lower gyroscope jitter out of lock, which can be simplified as resonance system two; the upper and lower jitter wheels are driven at the same frequency with a phase difference of 90°, which can also be simplified as resonance system three. Both systems one and two are the jitter resonance systems required by the dual-phase laser gyroscope, so they can provide good jitter effects. System three will have a negative impact. In order to reduce the impact of this system, counterweights with reverse jitter are designed, which greatly reduces the negative impact of system three, so as to eliminate the resonance system three and ensure the stability of the overall work. Even though there may be some differences in the jitter frequencies between the upper and lower jitter wheels due to slight processing differences, the middle value of the upper and lower jitter frequencies can be taken for jitter to ensure overall work efficiency. Appropriately lowering the Q value design can also increase system reliability and efficiency.

[0033] (4) The effect achieved by the present invention through the feature of step five is to improve the test accuracy and sensitivity of the inertial combination. Since the general inertial combination requires a master-slave inertial combination, this not only wastes space, but also requires more circuit assistance, and cannot avoid the influence of the dynamic lock area. This method can remove the influence of the lock area, cancel the backup inertial combination and greatly reduce the manufacturing cost. When the dual gyroscope is detected to have a problem, it can be directly switched to a single gyroscope through software. Although the accuracy and sensitivity will be lost, the basic functions of the single gyroscope inertial combination can still be realized to ensure the basic functions of the inertial combination. Furthermore, since the dual gyroscopes work together, this can not only improve the overall accuracy and sensitivity of the inertial combination, but also provide users with an inertial combination with higher reliability and stronger adaptability. Therefore, this method can greatly improve the performance of the previous inertial combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0035] Figure 1 A schematic diagram of a steering pulse of a dual-phase dither wheel gyroscope according to an embodiment of the present invention;

[0036] Figure 2 It is a schematic diagram of the design principle of the dual-phase dither wheel gyroscope driving circuit according to an embodiment of the present invention;

[0037] Figure 3 Schematic diagram of the overall design concept of the dual-phase laser gyroscope according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0039] The present invention proposes a design method of a dual-phase laser gyroscope, comprising:

[0040] Step 1: Process the laser gyroscope into two ultra-thin glass-ceramic cavities with good symmetry.

[0041] Divide the rectangular microcrystalline glass block into two gyroscope sizes. Then cut the two gyroscope cavities and align them side by side. Use a tool to drill a longitudinal hole in the center of the cavity for the two parallel laser gyros to form a unified shaking wheel bonding surface, i.e., the center hole. Use a parallel tool to drill transverse and longitudinal capillary holes for the two laser gyros. Then align the cathodes of the two cavities symmetrically outward, and use symmetrical tooling to process the cathodes. The processing of the positive and the positive can also be done by traditional processing methods to ensure good symmetry and consistency. The above methods are used to process two cavities with close symmetry and parallelism. In addition, in order to ensure the symmetry of the two gyroscopes, the total loss of the system composed of multiple sheets such as different reflectors needs to be adjusted when adjusting the cavity to ensure that the two gyroscopes have good loss consistency. The counterweight block (counterweight glass) is processed into a polygonal cavity. No drilling is required inside, but the quality of the counterweight block needs to be controlled. At the same time, the center of the counterweight block is also longitudinally drilled to form a center hole with good coaxiality (and the coaxiality of the upper and lower gyroscopes). It is also necessary to ensure that the weight is approximately consistent with the upper and lower gyroscope cavities.

[0042] The effect achieved by this step is that the upper and lower parts of the laser gyroscope have good coaxiality of the jitter wheel installation, and the cathode and anode capillary lengths are symmetrical, which ensures that the output pulse difference of the upper and lower gyroscopes under the same jitter intensity is small. At the same time, a simple symmetrical processing method is provided, which lays the foundation for the subsequent bonding of the jitter wheel and the combined demodulation of the two gyroscopes. The processing requirements of the counterweight block are also provided. The counterweight block can be made of the remaining glass in the gyroscope processing process to improve the material utilization efficiency.

[0043] Step 2: Propose the concept of a dual-phase dither wheel, design a dual-phase dither wheel, and bond the two ultra-thin gyroscope cavities to the dither wheel through the gyroscope cavity dither wheel bonding surface, and bond the dither wheel bonding surface of the counterweight block to the gyroscope counterweight block (the shape of the counterweight glass should be similar to the gyroscope cavity, and the mass should remain approximately the same).

[0044] The indium steel material is processed into eight-leaf or four-leaf shapes according to the traditional shaking wheel form. The small mounting holes of the four shaking wheels are processed in a through-type manner to ensure that the upper and lower gyroscopes are installed and fixed with good symmetry. A piezoelectric ceramic sheet is bonded to the blades of each shaking wheel, including a drive ceramic sheet and a feedback ceramic sheet. A total of three wires are drawn out, namely drive, ground, and feedback. The middle part is processed into a thicker cylinder to facilitate the rigid connection between multiple shaking wheels. The upper gyroscope and the upper counterweight are called the upper half, and the lower gyroscope and the lower counterweight are called the lower half. The upper half and the lower half are respectively double shaking wheel systems. To ensure that the shaking frequency is approximately the same, all shaking wheels use corresponding tooling to process the shaking leaves into the same wall thickness. The shaking wheel is bonded to the shaking wheel bonding surface of the upper gyroscope, upper counterweight, lower gyroscope, and lower counterweight, and then fastened to the installation box through the shaking wheel mounting hole.

[0045] Measure the dielectric constant before bonding the ceramics, and try to keep the dielectric constants of the upper and lower shaking wheel driving ceramics close, and the total capacitance value of the driving ceramics of the upper and lower shaking wheels close to the same.

[0046] The specific design of the upper and lower shaking wheels can be adopted in a variety of ways to meet the needs of different shaking frequencies and different vibration characteristics. During specific operations, the efficiency of the upper and lower shaking wheels can be tested separately. The efficiency of the upper and lower shaking wheels is guaranteed to differ by ≤1%. When the upper and lower shaking wheels are working at the same time, the dynamic efficiency of the upper and lower shaking wheels differs by ≤3%, so as to ensure that the upper and lower shaking wheels perform A / B demodulation under similar shaking amplitudes and reduce the error caused by the difference in shaking intensity. A rough bonding surface is used in the middle of the upper and lower shaking wheels. In order to have a good bonding and fixing effect, multiple reverse slots can even be designed to increase damping for fixing.

[0047] In addition, even if the jitter signal has a phase difference of 90°, the jitter of the same frequency will still form resonance and have a negative impact on the entire system. In order to effectively eliminate the resonance effect of the same frequency, two parallel-mounted counterweights of equal mass and shape are designed to perform reverse jitter with the jitter signals of the upper and lower gyroscopes, so as to eliminate the resonance effect of each jitter signal, so that the resonance energy of the entire system and the upper and lower subsystems is in a state close to a stable reference zero, thereby eliminating the resonance effect of the same jitter frequency.

[0048] The effect achieved by this step is: providing a design method for the core components of the dual-phase gyroscope, so that the upper and lower gyroscope cavities can achieve the same frequency and stable phase difference jitter under the condition of ensuring the same jitter frequency and jitter amplitude, and at the same time make the energy acting on the two cavities close to the same, and the AC signal frequency output by the two cavities is close to the same under the same energy. In addition, ensuring the consistency of parameters such as the dielectric constant and capacitance value of the ceramic can make the gyroscope have better adaptability, thereby providing strong support for the subsequent demodulation of the A / B signal and improving the sensitivity and accuracy of the gyroscope. Another point worth noting is that if the dual-phase jitter wheel is designed as an integral jitter wheel, then the jitter frequency, that is, its own resonant frequency point, has good consistency. At the same time, although the upper and lower jitter frequencies are the same frequency, the reverse jitter of the counterweight blocks of equal mass and shape can make the total resonance energy of the entire jitter system approximately zero, thereby greatly eliminating the negative impact of resonance and ensuring the overall working stability of the dual-phase gyroscope. In the inertial combination composed of general gyroscopes, reverse counterweight operation can also be performed to eliminate the negative impact of resonance.

[0049] Step 3: Design a shaking board to load four shaking drive signals with the same frequency and phase difference on four shaking wheels respectively, realize the orthogonal shaking of the upper and lower gyroscopes (phase difference of 90°), and realize the upper and lower counterweights to shake in the opposite direction with the upper and lower gyroscopes (phase difference of 180°), as shown in the figure. Figure 3shown.

[0050] according to Figure 2 The circuit principle diagram is used to design the jitter circuit board. Whether it is normal white noise injection or high and low three-state square waves or combined state jitter, the main jitter frequencies of the upper and lower sub-gyros need to be kept consistent, and the sum frequency is close in the static state. Specifically, write a single-chip computer program to output the control signal, output a certain waveform through the DDS method (a certain DA chip), and then output the jitter control signal with different waveform noise through logical operations (multipliers, etc.). After that, according to the drive control signal, the control signal phase shifting and noise injection operation is respectively realized after the phase shifter shifts the phase by 90° (or the software phase shift is used when the waveform is generated). Then, through the power amplifier circuit, the drive signal with the same jitter frequency with a phase difference of 90°, 180° (opposite to 0°), and 270° (opposite to 90°) can be realized, which are loaded on the gyro and the counterweight jitter wheel drive sheet respectively to complete the approximate same noise and same amplitude drive operation. The drive loaded on the counterweight block jitter wheel drive sheet can realize the counterweight reverse jitter to eliminate the resonance effect of the upper and lower jitter wheel systems respectively. The feedback signals of the upper and lower shaking wheels should theoretically also produce a 90° phase difference to achieve orthogonal shaking of the upper and lower laser gyroscopes. In addition, in order to achieve a closed-loop shaking, the DDS drive size of the two outputs is fine-tuned according to the feedback voltage of the piezoelectric or magnetic detection or photoelectric detection to stabilize the working state of the upper and lower four shaking wheels. In principle, it is necessary to ensure that the drive size difference of the upper and lower shaking wheels is ≤3% to ensure that the main energy and noise dynamic energy injected by the shaking wheels with similar drive capacitance are basically consistent, which is convenient for demodulation and solving stability and accuracy.

[0051] Step 4: Design a quadrature jittered four-way A / B signal demodulation system to achieve de-locking function

[0052] Four-way A / B signal demodulation system, two of which are AC photoelectric outputs of the upper gyroscope, and the other two are AC photoelectric outputs of the lower gyroscope. The upper and lower gyroscopes can obtain overlock steering information respectively according to the traditional demodulation method, so the time periods T1 and T2 of the upper and lower gyroscopes without overlock steering can be intercepted, such as Figure 1 As shown, after the outputs are combined, the combined output is demodulated similarly to the output of a single gyroscope in a traditional manner, and finally the anti-lock function is achieved by splicing.

[0053] Since the four-way A / B signal demodulation, the output of the gyro sensitive axis can be in the opposite or same direction, so according to the traditional demodulation method, the high-frequency clock can be used to perform logic trigger delay and operation on the upper and lower gyros respectively, and phase detection and direction determination operations can be performed respectively. Then, according to the results of phase detection and direction determination, the turning time point of the two shaking wheels can be obtained. The principle of phase detection and direction determination is that when the direction changes, the phase of the A / B two-way signal will be converted. When the phase is converted, the corresponding digital pulse is output to determine the turning position. Then, the midpoint of the two time points is used as the time limit. Combined with the turning midpoint of the two gyros, the pulse counting time range of the two boundaries can be T1, and the pulse counting time range of the next two boundaries can be T2. In the T1 time range, the pulse of the gyro without steering is selected for counting; in the T2 time range, the pulse of another gyro without steering is selected for counting in the same way. In this way, after splicing T1 and T2, the pulse output without the influence of the lock area can be obtained, and the problem of the gyro's sensitivity reduction caused by the lock area is reduced. It is particularly important to note that near the time point of the interception pulse, the software needs to confirm the number of pulses within the phase of positive and negative 90° near the last pulse to ensure that the A / B signals of each gyroscope appear in pairs at the interception point. According to the traditional demodulation method, the cw output signal and ccw output signal of one of the gyroscopes in the T1 time range are used to perform difference frequency calculation to obtain the signal cwa. The cw′ output signal and ccw′ output signal of the other gyroscope in the T2 time range are then used to perform difference frequency calculation to obtain the ccwa signal. After performing the difference frequency solution of the number of pulses respectively, cwa and ccwa are finally spliced ​​(or cw and cw′, ccw and ccw′ are spliced ​​and then the difference frequency solution is calculated according to the traditional method). Finally, the output result is uploaded to the software interface according to the frequency multiplication characteristics divided by the multiple of the frequency multiplication to obtain relevant information such as accuracy and output mean. The negative impact of the overlock zone can be removed when calculating the accuracy, while improving the sensitivity and accuracy to a certain extent. The sum frequency signals are respectively cw and ccw, which are calculated by traditional software to represent the jitter strength of the upper gyroscope, and cw′ and ccw′, which are calculated to represent the jitter strength of the lower gyroscope. The jitter strength of the upper and lower gyroscopes can be kept as close to the same as possible to ensure the accuracy and adaptability of the calculation results of splicing different time ranges during demodulation.

[0054] The effect achieved by the characteristics of steps three and four is the core demodulation step of the dual-phase laser gyroscope, which provides a guarantee for improving sensitivity and test accuracy. The demodulation of ordinary laser gyroscopes generally uses two A / B signals with a phase difference of 90° for phase detection demodulation and rotation direction determination. It is difficult to avoid the dynamic lock zone caused by jitter steering. It can only be continuously divided and reduced by injecting noise and increasing the jitter amplitude. The dual-phase laser gyroscope can use the upper and lower gyroscopes with jitter phase difference to demodulate the relationship between the four A / B signals. By cross-collecting the output of the area outside the lock zone and splicing it into a gyroscope output without a lock zone, the function of the laser gyroscope without a lock zone can be realized. In addition, when testing angular velocity, ordinary laser gyroscopes often cause some real data to be lost due to passing the lock zone. Even if the gyroscope with a high jitter frequency can greatly reduce the single-cycle lock zone time, it still cannot avoid the loss of sudden angular velocity information, which will have a certain negative impact on the test sensitivity and accuracy. This method provides a high-sensitivity and high-precision working solution through the cooperative demodulation of two gyroscopes with the same jitter frequency. Since the jitter wheels with the same jitter frequency will have a resonance effect even if there is a phase difference, the mechanical resonance formula can be approximately referred to: Vibration sine formula: The formula for a single degree of freedom system under simple harmonic force: In view of the fact that the resonance of the inertial combination of the three-axis laser gyroscope in different directions will affect the initial jitter and navigation of the gyroscope, three systems can be briefly established for the dual-phase laser gyroscope to analyze the resonance effect. The driving frequency of the upper jitter wheel is consistent with the natural frequency of the jitter wheel to produce resonance, which makes the upper gyroscope jitter out of lock, which can be simplified as resonance system one; the driving frequency of the lower jitter wheel with a phase difference is consistent with the natural frequency of the jitter wheel to produce resonance, which makes the lower gyroscope jitter out of lock, which can be simplified as resonance system two; the upper and lower jitter wheels are driven at the same frequency with a phase difference of 90°, which can also be simplified as resonance system three. Both systems one and two are the jitter resonance systems required by the dual-phase laser gyroscope, so they can provide good jitter effects. System three will have a negative impact. In order to reduce the impact of this system, counterweights with reverse jitter are designed, which greatly reduces the negative impact of system three, so as to eliminate the resonance system three and ensure the stability of the overall work. Even though there may be some differences in the jitter frequencies due to slight processing differences between the upper and lower jitter wheels, the middle value of the upper and lower jitter frequencies can be used for jittering to ensure overall work efficiency. Appropriately reducing the Q value design can also increase system reliability and efficiency.

[0055] Step 5: The high-precision mode and backup mode of the dual-phase gyro are automatically switched during the operation of the inertial combination.

[0056] When installing the gyro in each direction, the positive and negative sensitive axes are opposite or the same. When the gyro is normal, the high-precision mode is used, that is, the dual gyro works together. When a gyro in the inertial combination has a problem and cannot work normally, it can automatically switch to a single gyro. Although the working accuracy and sensitivity will be reduced, it can ensure the normal operation of the inertial combination in an emergency, and complete the fusion of the inertial combination and the backup inertial combination.

[0057] The effect achieved through step five is: improving the test accuracy and sensitivity of the inertial combination. Since the general inertial combination requires a master-slave inertial combination, this not only wastes space, but also requires more circuit assistance, and cannot avoid the influence of the dynamic lock area. This method can remove the influence of the lock area, cancel the backup inertial combination, and greatly reduce the manufacturing cost. When the dual gyroscopes detect problems, they can be directly switched to a single gyroscope through software. Although the accuracy and sensitivity will be lost, the basic functions of the single gyroscope inertial combination can still be realized to ensure the basic functions of the inertial combination. Furthermore, since the dual gyroscopes work together, this can not only improve the overall accuracy and sensitivity of the inertial combination, but also provide users with a more reliable and adaptable inertial combination. Therefore, this method can greatly improve the performance of the previous inertial combination.

[0058] The present invention solves the problems of test accuracy of multiple types of laser gyroscopes, reduces the negative impact of the lock area on the laser gyroscope, improves the accuracy and stability of the laser gyroscope, and can integrate the working inertial combination and the backup inertial combination in this way, thereby greatly reducing the volume, weight and cost. When both gyros are working normally, the dual gyros work together to improve the overall performance of the inertial combination, and are in an efficient working mode. When a single gyro in a certain direction has a problem, the inertial combination software recognizes and automatically switches to a single gyro inefficient working mode. Although some accuracy and sensitivity advantages will be lost, the backup inertial combination system can play an emergency role when problems occur, and the startup hot state time is saved. While improving the overall performance of the inertial combination, the power consumption and cost are reduced, and a more efficient inertial combination system is provided to users.

[0059] The above-described embodiments are only preferred specific implementations of the present invention. Common changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included in the protection scope of the present invention.

Claims

1. A design method for a dual-phase laser gyroscope, characterized in that: include: Step 1: Process two symmetrical glass-ceramic cavities; Step 2: Bond the dual-phase shaking wheel to two glass-ceramic cavities to form an upper and lower gyroscope; and provide a counterweight block with a shaking wheel for each of the upper and lower gyroscopes; Step 3: The shaking board generates four shaking driving signals with the same frequency and phase difference and loads them on four shaking wheels, so that the upper and lower gyroscopes shake orthogonally and the two counterweights shake in the opposite direction relative to the gyroscope on the same side; Step 4: Establish a four-channel A / B signal demodulation system with orthogonal jitter, receive the four-channel photoelectric signals output by the upper and lower gyroscopes, obtain the overlock steering information, intercept the time period information of the upper and lower gyroscopes without overlock steering, splice and output.

2. The design method of a dual-phase laser gyroscope according to claim 1, characterized in that: In step 2, four shaking wheels are processed by indium steel material; the mounting holes of the four shaking wheels are processed by through-type method; a group of piezoelectric ceramic sheets are bonded to the blades of each shaking wheel, including a driving ceramic sheet and a feedback ceramic sheet, and three wires are led out, namely a driving wire, a ground wire, and a feedback wire; The two shaking wheels are bonded to two glass-ceramic cavities to form an upper gyroscope and a lower gyroscope. The other two shaking wheels are respectively connected to two counterweights. The counterweight connected to the upper gyroscope is called an upper counterweight, and the counterweight connected to the lower gyroscope is called a lower counterweight.

3. The design method of a dual-phase laser gyroscope according to claim 2, characterized in that: In step 2, the piezoelectric ceramic sheets bonded to the blades of each shaking wheel have the same dielectric constant, and the total capacitance value of the driving ceramic sheets is the same.

4. The design method of a dual-phase laser gyroscope according to claim 1, characterized in that: The dither board outputs two drive control signals through DDS mode. One signal is phase-shifted by 90° and then passes through the same noise multiplier with the other signal to realize phase shifting and noise injection of the drive control signal. The signal is then amplified through a power amplifier circuit to obtain a dither drive signal with the same dither frequency and a 90° phase difference. The signal is loaded on the upper and lower gyro dither wheels. The feedback signals of the upper and lower dither wheels also produce a 90° phase difference to realize orthogonal dithering and closed-loop control of the upper and lower gyroscopes.

5. The design method of a dual-phase laser gyroscope according to claim 4, characterized in that: The two obtained shaking driving signals are phase-shifted by 180° and loaded on the shaking wheels of the two counterweights respectively, so that the counterweights can shake in opposite directions relative to the gyroscopes on the same side and eliminate the resonance effect.

6. The design method of a dual-phase laser gyroscope according to claim 4, characterized in that: Establish a four-way signal demodulation system with orthogonal jitter to process: Receiving two AC photoelectric signals output by the upper gyro and two AC photoelectric signals output by the lower gyro, and demodulating them respectively to obtain the overlock steering information of the upper and lower gyros; The time periods of the upper and lower gyroscopes without overlock steering are intercepted, and within each time period, the difference frequency calculation is performed on the two signals output within each time period; the calculated signals are spliced ​​and then output.

7. The design method of a dual-phase laser gyroscope according to claim 1, characterized in that: During the operation of the inertial group, the gyroscope has a high-precision mode and a backup mode. Under normal circumstances, the high-precision mode is used, that is, the dual gyroscopes work together. When a gyroscope has a problem and cannot work normally, it automatically switches to a single gyroscope.

8. The design method of a dual-phase laser gyroscope according to claim 1, characterized in that: The driving frequency of the upper shaking wheel is consistent with the natural frequency of the shaking wheel, which produces resonance and causes the upper gyroscope to shake and lock; The driving frequency of the lower shaking wheel with a phase difference is consistent with the natural frequency of the shaking wheel, which produces resonance and causes the lower gyroscope to shake and unlock.

9. The design method of a dual-phase laser gyroscope according to claim 1, characterized in that: In step 1, the method for processing two symmetrical glass-ceramic cavities is as follows: Divide the rectangular glass-ceramic block into two gyroscope-sized pieces; Cut two glass-ceramic cavities, align them side by side, and use a cutter to drill holes longitudinally in the center of the two parallel and aligned glass-ceramic cavities to form a unified shaking wheel bonding surface; Drill two transverse and longitudinal capillaries of glass-ceramics using parallel tools; The cathodes of two microcrystalline glass cavities are placed symmetrically and aligned outward, the cathodes are processed with symmetrical tooling, and then the positive electrode extraction and general positive electrode processing are performed to obtain two symmetrical microcrystalline glass cavities.

10. The design method of a dual-phase laser gyroscope according to claim 1, characterized in that: The material of the counterweight block is microcrystalline glass. The cavity of the counterweight block is longitudinally drilled to form a bonding surface for the shaking wheel. After installation, the hole of the counterweight block is coaxial with the holes of the upper and lower gyroscopes.

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