A method for enhancing the random noise injection efficiency of a mechanically dithered laser gyroscope

Abstract

The application discloses a method for enhancing random noise injection efficiency of a mechanical dithering laser gyroscope, which comprises judging the level of a pseudo-random noise signal, positively enhancing the amplitude of the random noise signal if the level of the random noise signal changes from a high level to a low level, reversely enhancing the amplitude of the random noise signal if the level of the random noise signal changes from the low level to the high level, and not changing the amplitude of the random noise signal if the level of the random noise signal does not change from the high level to the low level or from the low level to the high level; obtaining a variety of state random change noise signals according to the amplitude signal of the random change, converting the noise signals into a variety of duty cycle random change three-state square wave signals, and taking the three-state square wave signals as input signals of a dithering mechanism transfer function; the method significantly suppresses the serious attenuation phenomenon of high-frequency noise amplitude, improves the random noise injection efficiency, reduces angle random walk, and thus improves the precision of the laser gyroscope.

Description

Technical Field

[0001] This invention belongs to the field of laser gyroscope technology, and particularly relates to a method for enhancing the random noise injection efficiency of mechanically jittered laser gyroscopes. Background Technology

[0002] Currently, mechanically jittered laser gyroscopes often employ pseudo-random noise injection to eliminate the impact of dynamic locking on gyroscope performance. Therefore, random noise injection is a key technology for improving laser gyroscope performance. This invention theoretically studies the transfer function of the jittering mechanism, obtains the transfer function of random noise in the laser gyroscope, and further derives the specific low-pass filtering characteristics of the random noise transfer function. Therefore, during random noise injection, the amplitude of high-frequency random noise in mechanically jittered laser gyroscopes undergoes severe attenuation, a phenomenon that hinders further performance improvement. To address this issue, this invention establishes a transfer function to enhance random noise injection efficiency based on the random noise transfer function and proposes a method for enhancing random noise injection efficiency based on changes in random noise level. Simulation verification and experimental testing show that, compared to the original random noise injection method, the method of enhancing random noise injection efficiency significantly suppresses the severe attenuation of high-frequency noise amplitude during random noise injection in the laser gyroscope. Summary of the Invention

[0003] The technical problem to be solved by this invention is to provide a method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope, thereby suppressing the severe attenuation of high-frequency random noise during pseudo-random noise injection, a phenomenon that affects the further improvement of the performance of the mechanically jittered laser gyroscope.

[0004] The technical solution of this invention is:

[0005] A method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope, the method comprising:

[0006] Step 1: Determine the level of the pseudo-random noise signal. When the level of the random noise signal changes from high to low, the amplitude of the random noise signal increases positively; when the level of the random noise signal changes from low to high, the amplitude of the random noise signal increases negatively; when the level of the random noise signal does not change from high to low or from low to high, the amplitude of the random noise signal remains unchanged.

[0007] Step 2: Based on the judgment of the random noise level changes, obtain noise signals with multiple states of random variation;

[0008] Step 3: Convert the noise signal with multiple states that change randomly into a three-state square wave signal with multiple duty cycles that change randomly;

[0009] Step 4: Use the three-state square wave signal as the input signal for the transfer function of the jitter mechanism.

[0010] The pseudo-random noise signal is a 23-level pseudo-random sequence.

[0011] The noise signal with multiple randomly changing states is a noise signal with four randomly changing states; the random noise signal with four states is implemented by pseudo-random noise and multiplexer.

[0012] The aforementioned three-state square wave signals with randomly varying duty cycles are four types of three-state square wave signals with randomly varying duty cycles.

[0013] The pseudo-random noise signal is implemented by a 23-stage delay circuit.

[0014] The original random noise injection method involves randomly selecting two square wave signals with different duty cycles from random noise.

[0015] The method for generating three-state square wave signals is as follows: In the simulation model, random noise signals are combined with counters and comparators to convert four random noise signals into four three-state square wave signals with randomly varying duty cycles.

[0016] The method of using the three-state square wave signal as the input signal of the jitter mechanism transfer function is as follows: four different square wave signals are randomly selected using pseudo-random noise signal, and the randomly selected square wave signal is used as the input signal of the jitter mechanism transfer function.

[0017] The beneficial effects of this invention are:

[0018] This invention uses level changes in pseudo-random noise signals to positively or negatively enhance the amplitude of random noise signals. When the level does not change, the amplitude of the random noise signal remains unchanged. This random noise injection method improves the random noise injection efficiency of mechanically jittered laser gyroscopes, effectively suppresses the severe attenuation of random noise during the random noise injection process, and reduces angular random walk, thereby improving the accuracy of laser gyroscopes.

[0019] In mechanically jittered laser gyroscopes, simulation models and experimental tests show that the method for enhancing the random noise injection efficiency of mechanically jittered laser gyroscopes, compared with the original random noise injection method, increases the frequency component of the high-frequency noise amplitude, improves the random noise injection efficiency, enhances the ability to eliminate dynamic locking regions of mechanically jittered laser gyroscopes, and improves the performance of mechanically jittered laser gyroscopes. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the process for enhancing the efficiency of random noise injection according to the present invention;

[0021] Figure 2 To illustrate the amplitude relationship between the enhanced noise and the original noise-enhanced random noise signal;

[0022] Figure 3 Time-domain plot of the jitter amplitude signal output by the simulation model;

[0023] Figure 4 The spectrum of the jitter amplitude signal output by the simulation model;

[0024] Figure 5 This is a diagram of the jitter driving signal for improving the random noise injection efficiency of the present invention;

[0025] Figure 6 This is a time-domain plot of the jitter amplitude in the experimental test data of this invention;

[0026] Figure 7 This is a spectrum of jitter amplitude in the experimental test data of this invention. Detailed Implementation

[0027] This invention modifies the amplitude of a random noise signal based on the level changes of the pseudo-random noise signal. Specifically, when the level of the random noise signal changes from high to low, the amplitude of the random noise signal increases positively; when the level of the random noise signal changes from low to high, the amplitude of the random noise signal increases negatively; otherwise, the amplitude of the random noise signal remains unchanged. This method of randomly changing noise amplitude yields noise signals with multiple states of random variation, which are then converted into three-state square wave signals with multiple randomly changing duty cycles. These three-state square wave signals are used as the input signal to the transfer function of the jittering mechanism. The changes in the output signal of the jittering mechanism's transfer function in the time and frequency domains are observed and compared with the original random noise injection method to determine whether the noise amplitude has been enhanced and whether the severe attenuation of high-frequency noise amplitude has been effectively suppressed. The original random noise injection method randomly selects two square wave signals with different duty cycles.

[0028] This method, which uses the level change of the random noise signal as a criterion to randomly alter the amplitude of the random noise signal, effectively suppresses the severe attenuation of high-frequency noise amplitude during the injection process of the mechanically jittered laser gyroscope and improves the random noise injection efficiency of the laser gyroscope. Simulation results and experimental tests show that, compared with the original random noise injection method, the method that enhances the random noise injection efficiency significantly suppresses the severe attenuation of high-frequency noise amplitude and improves the random noise injection efficiency of the laser gyroscope, while reducing angular random walk, thereby improving the accuracy of the mechanically jittered laser gyroscope and enhancing its performance.

[0029] The invention will now be described in further detail with reference to the accompanying drawings. Please refer to the accompanying drawings. Figure 1As shown, this is a flowchart of enhanced random noise injection, including pseudo-random noise 1. If the level of the random noise signal changes from high level to low level 2, the amplitude of the random noise signal is positively enhanced 3; if the level of the random noise signal changes from low level to high level 4, the amplitude of the random noise signal is negatively enhanced 5; otherwise, the amplitude of the random noise signal remains unchanged 6. Through this enhanced random noise injection method, noise signals with multiple states of random variation 7 are obtained, and then the noise signals with multiple states of random variation 7 are converted into three-state square wave signals with multiple duty cycles of random variation 8.

[0030] A simulation model was built based on the technical solution to enhance the efficiency of random noise injection. Since pseudo-random sequences are implemented in digital circuits by shifting multiple D flip-flops, delay modules can be used in Simulink to implement pseudo-random sequences. Because random noise injection randomizes the jitter amplitude of the laser gyroscope, making its entry and exit from the lock zone random, thus reducing the time the laser gyroscope spends in the lock zone, but if the period of the random noise is short, the randomization period of the jitter amplitude during the gyroscope's operating time may become shorter, failing to achieve the goal of minimizing the time the gyroscope spends in the lock zone. Therefore, to ensure that the random noise period of the gyroscope does not repeat over a longer period during its operating time, this invention uses a 23-stage delay circuit to implement the pseudo-random noise model.

[0031] When the level of random noise decreases from high to low, the amplitude of the random noise increases, achieving positive enhancement; when the level of random noise increases from low to high, the amplitude of the random noise decreases, achieving negative enhancement. In other cases, the amplitude of the random noise remains unchanged. The relationship between the amplitude of the enhanced noise and the amplitude of the original noise is shown below. Figure 2 As shown, the solid line represents the noise amplitude under the original noise addition, and the star line represents the noise amplitude under enhanced noise addition.

[0032] To generate a random noise signal with four states, two additional states need to be added to the existing random noise signal. This can be achieved using a multiplexer in Simulink. Since the jitter drive signal typically uses a sine wave, which is much more complex to implement in circuits than a square wave, this invention uses a square wave signal with constant amplitude and adjustable duty cycle as the drive signal for the jitter mechanism. Therefore, the four-state random noise signal needs to be converted into four three-state square wave signals with randomly varying duty cycles. This can be achieved in Simulink using counters and relational operators. The converted three-state square wave signal is then used as the input signal to the transfer function of the jitter mechanism. Analyzing the amplitude of the output signal of the transfer function yields the time-domain graph as shown below. Figure 3 As shown, the solid line represents the jitter amplitude signal under the original random noise injection method, and the star line represents the jitter amplitude signal under the enhanced random noise injection method; the spectrum diagram is shown below. Figure 4As shown, the solid line represents the frequency domain of the noise amplitude under the original random noise injection method, and the star line represents the frequency domain of the noise amplitude under the enhanced random noise injection method. Simulation results show that the method of enhancing random noise injection efficiency significantly suppresses the severe attenuation of high-frequency noise and improves the injection efficiency of random noise.

[0033] After completing the simulation verification, it is necessary to design the software for random noise enhancement injection efficiency. This invention implements the software design based on FPGA and conducts experimental testing in conjunction with the built experimental platform. The code is written using Verilog HDL hardware description language. Since the original random noise injection method's driving signal is a three-state square wave signal with two randomly changing duty cycles, after random noise enhancement injection, the driving signal becomes a three-state square wave signal with four randomly changing duty cycles. Therefore, it is necessary to determine the change in random noise level to realize the software design for random noise enhancement injection. The specific method is as follows: when the random noise signal is (00)2, the duty cycle of the square wave signal is set to 87% and 13%; when the random noise signal is (01)2, the duty cycle of the square wave signal is set to 90% and 10%; when the random noise signal is (10)2, the duty cycle of the square wave signal is set to 85% and 15%; when the random noise signal is (11)2, the duty cycle of the square wave signal is set to 95% and 5%. The driving square wave signal for random noise enhancement injection efficiency is as follows: Figure 5 As shown.

[0034] The experimental data from the test were processed to obtain the time-domain graph of the jitter amplitude signal, as shown below. Figure 6 As shown, the solid line represents the jitter amplitude signal under the original random noise injection method, and the star line represents the jitter amplitude signal under the enhanced random noise injection method; the spectrum of the jitter amplitude signal is shown below. Figure 7 As shown, the solid line represents the spectrum of the jitter amplitude signal under the original random noise injection method, and the star line represents the spectrum of the jitter amplitude signal under the enhanced random noise injection method. The results show that the method of enhancing injection efficiency with random noise significantly suppresses the severe attenuation of high-frequency noise, improves the injection efficiency of random noise, reduces angular random walk, and improves the accuracy of the laser gyroscope.

Claims

1. A method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope, characterized in that: The method includes: Step 1: Determine the level of the pseudo-random noise signal. When the level of the random noise signal changes from high to low, the amplitude of the random noise signal increases positively; when the level of the random noise signal changes from low to high, the amplitude of the random noise signal increases negatively; when the level of the random noise signal does not change from high to low or from low to high, the amplitude of the random noise signal does not change. Step 2: Following the method in Step 1, obtain noise signals with multiple randomly changing states; Step 3: Convert the noise signal with multiple states that change randomly into a three-state square wave signal with multiple duty cycles that change randomly; Step 4: Use the three-state square wave signal as the input signal for the transfer function of the jitter mechanism.

2. The method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope according to claim 1, characterized in that: The pseudo-random noise signal is a 23-level pseudo-random sequence.

3. The method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope according to claim 1, characterized in that: The noise signal with multiple states changing randomly is a noise signal with four states changing randomly; the random noise signal with four states is realized in the simulation model by pseudo-random noise and multiplexer.

4. The method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope according to claim 1, characterized in that: The aforementioned three-state square wave signals with randomly varying duty cycles are four types of three-state square wave signals with randomly varying duty cycles.

5. The method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope according to claim 1, characterized in that: The pseudo-random noise signal is implemented by a 23-stage delay circuit.

6. The method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope according to claim 1, characterized in that: The method for generating three-state square wave signals is as follows: In the simulation model, random noise signals are combined with counters and comparators to convert four random noise signals into four random three-state square wave signals with four random duty cycles.

7. The method for enhancing the random noise injection efficiency of a mechanically jittered laser gyroscope according to claim 1, characterized in that: The method of using a three-state square wave signal as the input signal of the jitter mechanism transfer function is as follows: four square wave signals with different duty cycles are randomly selected using pseudo-random noise signals to obtain the input signal of the jitter mechanism transfer function.

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