A laser gyro jitter bias frequency control device and method based on frequency modulation

Abstract

The present invention proposes a laser gyro jitter bias frequency control device based on frequency modulation, characterized in that it includes: a jitter feedback module for obtaining a jitter signal of a laser gyro; a frequency modulation module, wherein a sinusoidal signal generated by the jitter feedback module is input into the jitter feedback module to control the jitter of the laser gyro, and at the same time, the jitter signal is input into the frequency modulation module to adjust the sinusoidal signal. The present invention also proposes a method, comprising: S1, using a first signal to stimulate gyro jitter, wherein the first signal is a sinusoidal signal; S2, collecting a jitter feedback signal of gyro jitter; S3, adjusting the frequency of the sinusoidal signal based on the jitter feedback signal, and then using the adjusted sinusoidal signal to stimulate the laser gyro, so that the laser gyro can work stably at the resonance point. The circuit of the present invention adopts a frequency modulation method, and has few components and a small size.

Description

Technical Field

[0001] The present invention relates to the technical field of laser gyroscopes, and more specifically to a laser gyroscope jitter deviation frequency control device and method based on frequency modulation. Background Art

[0002] The laser gyroscope is an optical device that is sensitive to inertial angular velocity and is manufactured based on the Sagnac effect. Compared with other types of gyroscopes, it has the characteristics of high precision, strong resistance to harsh environments, large dynamic range, and high reliability. In the laser gyroscope, due to the existence of backscattering and non-uniform loss, when the input rotation speed is lower than a certain threshold, the frequencies of the two beams moving in opposite directions will become synchronized, so that the laser gyroscope has no output signal. This phenomenon is called the locking effect of the laser gyroscope. In order to eliminate the locking effect, the laser gyroscope usually increases mechanical jitter to make the dead zone of the laser gyroscope a dynamic dead zone. The laser gyroscope using this method is called a mechanical jitter laser gyroscope. As the earliest practical and most widely used laser gyroscope, the mechanical jitter laser gyroscope (abbreviated as machine-jitter laser gyroscope) has been widely used in important fields such as inertial navigation and angle measurement.

[0003] In the prior art, patent application 2019110819619 "A PSD-based laser gyro jitter detection device and method" discloses a jitter frequency control technology, which is implemented by analog circuits; using analog circuits to control the jitter of mechanical jitter laser gyros, there are many types of components, and the control algorithm and parameter adjustment are inconvenient, which makes the control circuit board bulky and is not conducive to the miniaturization and precision improvement of laser gyros. Some technologies use partial digital control (invention patent CN202229762U "A laser gyro digital machine jitter control circuit").

[0004] Invention patent application 20192224244786 ("An anti-interference method for a jitter control system of a machine-jitter laser gyroscope") discloses a jitter control method for a machine-jitter laser gyroscope, which processes the jitter control signal of the gyroscope. This method superimposes a reverse interference signal in the drive signal to eliminate the interference noise in the input signal of the jitter mechanism. This method has a large zero-crossing detection phase noise, and the signal-to-noise ratio cannot be guaranteed. It also uses amplitude PID operation and phase PID operation. Given a sine wave of a specific frequency, the phase is detected and the frequency is changed so that the phase difference between the jitter drive signal and the jitter feedback signal is equal to 180 degrees, the jitter wheel oscillates, and the operation method is complicated, which will result in a long operation time for the control chip and a slow processing speed for the device. Summary of the invention

[0005] In order to solve the problems in the background technology, the present invention proposes a laser gyro jitter bias frequency control device based on frequency modulation, including: a jitter feedback module for obtaining a jitter signal of the laser gyro; a frequency modulation module, wherein a sinusoidal signal generated by the jitter feedback module is input into the jitter feedback module to control the jitter of the laser gyro, and at the same time, the jitter signal of the laser gyro collected by the jitter feedback module is input into the frequency modulation module to adjust the sinusoidal signal.

[0006] The present invention also proposes a laser gyro jitter bias frequency control method based on frequency modulation, comprising: S1, using a first signal to stimulate gyro jitter, wherein the first signal is a sinusoidal signal; S2, collecting a jitter feedback signal of the gyro jitter; S3, adjusting the frequency of the sinusoidal signal based on the jitter feedback signal, and then using the adjusted sinusoidal signal to stimulate the laser gyro, so that the laser gyro can work stably at the resonance point.

[0007] The technical effects of the present invention include: the control device is fully digitalized, the control algorithm and parameter adjustment are simple, the circuit components are few, and the volume is smaller. The multiplication phase detection is adopted, the noise is small, and the control accuracy is higher. Only the frequency PID operation is used to control the signal phase and the noise is added to make the oscillating wheel work stably at the resonance point. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to make the present invention more easily understood, the present invention will be described in more detail by referring to the specific embodiments shown in the accompanying drawings. These drawings only depict typical embodiments of the present invention and should not be considered as limiting the scope of protection of the present invention.

[0009] Figure 1 It is a schematic diagram of the device of the present invention.

[0010] Figure 2 is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0011] The following describes the implementation modes of the present invention with reference to the accompanying drawings so that those skilled in the art can better understand the present invention and implement it. However, the enumerated embodiments are not intended to limit the present invention. In the absence of conflict, the following embodiments and the technical features in the embodiments may be combined with each other, wherein the same components are represented by the same figure marks.

[0012] like Figure 1 As shown, the principle of the device of the present invention is to generate a sinusoidal signal to excite the gyro to shake. The feedback signal of the gyro shaking is collected and then used to feed back the sinusoidal signal, so that the laser gyro can work stably at the resonance point.

[0013] Specifically, the device of the present invention includes: a frequency modulation module and a jitter feedback module. The jitter feedback module includes: a jitter feedback unit, a reverse amplifier, and a driving amplifier. The frequency modulation module includes: an ADC unit, a DAC unit, and a frequency PID controller. Specifically, the output of the jitter feedback unit is connected to the reverse amplifier. The output of the reverse amplifier is connected to the ADC unit. The feedback signal of the jitter feedback unit is connected to the reverse amplifier and amplified, and the function of the amplification is to enable the ADC unit to collect signal data.

[0014] The output of the DAC is connected to the input of the driving amplifier. The DAC looks up the sine table stored in the memory and generates a sinusoidal signal to stimulate the gyro to shake. Specifically, the DAC looks up the sine table stored in the memory and sends a first signal y1(t) to the driving amplifier. The first signal y1(t) is a sinusoidal signal y1(t) = sin(ω0t) with a fixed frequency and amplitude. After receiving the jitter drive signal output by the driving amplifier, the jitter feedback unit controls the gyro wheel to shake and outputs a jitter feedback signal. The reverse amplifier amplifies the jitter feedback signal so that the ADC of the MCU can collect the jitter feedback signal. The second signal x(t) output by the ADC is the jitter feedback signal.

[0015] The second signal x(t) and the third signal y(t) output by the ADC unit are input to the first multiplier, multiplied by the first multiplier, and then input to the low-pass filter LPF. The current phase error is obtained. The output of the low-pass filter is connected to the frequency PID control unit. Therefore, the phase error err is the input of the frequency PID control unit. The frequency PID control unit changes the output step size λ of the sine table according to the phase error err (the table can be downloaded to the MCU) to generate a third signal y(t). The third signal y(t) is input and the noise signal to the second multiplier, and the output of the second multiplier is connected to the DAC to adjust the frequency of the sinusoidal signal y1(t) output by the DAC. In this way, by controlling the phase of the jitter drive signal, the phase difference between the jitter drive signal and the jitter feedback signal gradually approaches 90°. When the phase difference between the jitter drive signal and the jitter feedback signal is 90°, the system is stable.

[0016] Furthermore, a simple jitter frequency deviation will cause the gyro to frequently enter and exit the locking area, and each time a small error will be generated. Although the error is small, it will be accumulated over time and eventually manifested as a large error, which is called a dynamic locking error. In order to further reduce the dynamic locking error, it is necessary to inject a random noise into the alternating jitter, which can be introduced through the noise output unit. The standard noise spectrum is stored in the memory and can be obtained and introduced by looking up the table. The amplitude of the white noise can be controlled by multiplying the required amplitude with the noise spectrum. The random noise modulates the amplitude of the jitter, causing the jitter amplitude to change randomly, thereby randomizing the error caused by entering and exiting the locking area. The average value of the error in multiple jitter cycles tends to zero, which can effectively reduce the dynamic locking error of the machine-jittered laser gyro and improve the control accuracy. This device introduces Gaussian white noise after the amplitude PID control module, and the noise signal is multiplied by the third signal and input into the DAC. The accuracy of the gyro is affected by many factors. The amplitude of the introduced Gaussian white noise is controllable, which can optimize the accuracy of the gyro.

[0017] In one embodiment, the DAC, ADC, low-pass filter, and frequency PID control unit can be integrated into one chip as an MCU. In this way, the operation of the control process is all realized by the MCU digital chip operation, the control algorithm and parameter adjustment are simple, the circuit components are few, and the volume is smaller.

[0018] According to another aspect of the present invention, Figure 2 As shown, a laser gyro jitter bias frequency control method based on frequency modulation is proposed. In step S1, a first signal is used to stimulate gyro jitter, wherein the first signal is a sinusoidal signal. S2, a jitter feedback signal of the gyro jitter is collected. S3, the frequency of the sinusoidal signal is adjusted based on the jitter feedback signal, and the adjusted sinusoidal signal is used to stimulate the laser gyro, so that the laser gyro works stably at the resonance point.

[0019] Furthermore, in S1, the first signal y1(t) is a sinusoidal signal y1(t)=sin(ω0t) with a fixed frequency and amplitude. After receiving the first signal, the jitter feedback unit of the laser gyro controls the gyro wheel to jitter and outputs a jitter feedback signal.

[0020] In S2, the jitter feedback signal is amplified using an inverting amplifier.

[0021] In S3, the jitter feedback signal is collected using an ADC, and the ADC outputs a second signal x(t). The second signal is multiplied by the third signal, and then filtered through a low-pass filter to obtain the current phase error. Then, after frequency PID control is performed, the sine table is searched to obtain an adjusted sine signal (the frequency PID control unit changes the sine table output step length λ according to the phase error err), wherein the adjusted sine signal is the third signal.

[0022] Step S3 also includes: multiplying the third signal and the noise signal, and converting the result through DAC to form the first signal in step S1.

[0023] The embodiments described above are only preferred specific implementations of the present invention. This specification uses the phrases "in one embodiment", "in another embodiment", "in yet another embodiment" or "in other embodiments" to refer to one or more of the same or different embodiments according to the present disclosure. 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 laser gyro jitter bias frequency control device based on frequency modulation, characterized in that: include: A jitter feedback module for obtaining a jitter signal of the laser gyro and outputting a jitter feedback signal; The frequency modulation module includes: an ADC unit, a DAC unit, a low-pass filter, a noise output unit and a frequency PID control unit. Among them, the DAC unit generates a first signal for stimulating the laser gyro to shake, and the first signal is a sinusoidal signal; the ADC unit receives the jitter feedback signal; the output of the low-pass filter is connected to the frequency PID control unit; the second signal output by the ADC unit and the third signal related to the output of the frequency PID control unit are input into the first multiplier, and the output of the first multiplier is connected to the low-pass filter; the third signal and the output signal of the noise output unit are connected to the second multiplier, and the output of the second multiplier is connected to the DAC unit as an input signal, and the output signal of the DAC unit is used as the sinusoidal signal; the frequency PID control unit changes the output step size of the sine table according to the phase error output by the low-pass filter to generate the third signal.

2. The laser gyro jitter bias frequency control device based on frequency modulation according to claim 1, characterized in that: The jitter feedback module comprises: A jitter feedback unit, an inverse amplifier and a driving amplifier are used to obtain a jitter signal of a laser gyroscope, wherein the output of the jitter feedback unit is connected to the inverse amplifier, the output of the inverse amplifier is connected to the frequency modulation module, the output of the frequency modulation module is connected to the driving amplifier, and the output of the driving amplifier is connected to the jitter feedback unit.

3. The laser gyro jitter bias frequency control device based on frequency modulation according to claim 2, characterized in that: The output of the inverting amplifier is connected to the ADC unit, and the output of the DAC unit is connected to the driving amplifier.

4. The laser gyro jitter bias frequency control device based on frequency modulation according to claim 3, characterized in that: The third signal and the output signal of the noise output unit are connected to a second multiplier, the output of the second multiplier is connected to a DAC unit as an input signal, and the output signal of the DAC unit is input to the driving amplifier as the sinusoidal signal.

5. A laser gyro jitter bias frequency control method based on frequency modulation, characterized in that: include: S1, using a first signal to stimulate gyro jitter, wherein the first signal is a sinusoidal signal; S2, collecting the jitter feedback signal of the gyro jitter; S3, adjusting the frequency of the sinusoidal signal based on the jitter feedback signal, and then using the adjusted sinusoidal signal to excite the laser gyro so that the laser gyro works stably at a resonance point, including: After the ADC collects the jitter feedback signal, it outputs a second signal; multiplies the second signal and the third signal, and then filters it through a low-pass filter; changes the output step of the sine table through frequency PID control according to the phase error output by the low-pass filter to generate a third signal; multiplies the third signal and the noise signal, and then converts it through a DAC to form the first signal in step S1.

6. The laser gyro jitter bias frequency control method based on frequency modulation according to claim 5, characterized in that: In S1, the first signal is a sinusoidal signal with a fixed frequency and amplitude. After receiving the first signal, the jitter feedback unit of the laser gyro controls the gyro wheel to shake and outputs a jitter feedback signal. In S2, a reverse amplifier is used to amplify the jitter feedback signal.

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