Digital jitter drive control circuit and working method of laser gyro lock area

Abstract

The digital jitter drive control circuit and working method of the laser gyro lock area are closer to the ideal linear output, fast start-up and jitter recovery, high frequency tracking accuracy, and the jitter amplitude is large enough and stable, which improves the measurement accuracy of the gyro in a variable temperature environment. The circuit includes a jitter drive control circuit, a jitter drive circuit, a jitter mechanism, a resonant cavity, and a signal shaping circuit through which the signal passes in sequence; the jitter drive control circuit includes: an amplitude control loop, a frequency control loop, and a pulse width control circuit; the mechanical jitter frequency deviation is obtained by quadruple frequency phase counting, and the amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude; the frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency according to the frequency feedback signal; the pulse width control circuit compares the mechanical jitter amplitude and the real-time mechanical jitter frequency as reference objects, calculates the error according to the mechanical jitter amplitude benchmark, and then performs real-time control to compensate for the change.

Description

Technical Field

[0001] The present invention relates to the technical field of digital circuits, and in particular to a digital jitter drive control circuit in a laser gyro lock zone, and a working method of the digital jitter drive control circuit in a laser gyro lock zone. Background Art

[0002] Laser gyroscopes are widely used in inertial navigation systems due to their high precision, small size and low cost. One of their positioning functions in the system is to measure the rotation speed of the moving carrier and sense its posture.

[0003] like Figure 1 As shown, one of the problems of the laser gyroscope is the lock-zone effect. The lock-zone effect means that when the carrier rotation speed sensed by the laser gyroscope is less than a certain value, the output angular frequency difference of the laser gyroscope is 0, and the corresponding rotation speed cannot be calculated.

[0004] The locking zone is caused by the non-uniform loss of light in the propagation direction and the interference of the backscattered light from the reflectors.

[0005] The solution to the laser gyro lock area problem is to bypass or break up the lock area. You can start from the following aspects:

[0006] 1. Start with the device itself: develop and process higher quality reflectors.

[0007] 2. Adding bias frequency signal: The most commonly used and successful bias frequency method is mechanical dither bias frequency method. In this method, the laser gyro body is in the driving device (such as Figure 2 As shown), a sinusoidal alternating jitter is generated (as shown Figure 4 as shown).

[0008] The traditional amplitude jitter control loop uses the mechanical jitter frequency deviation as the comparison object. According to the formula for eliminating the laser gyro lock area, the mechanical jitter frequency deviation = mechanical jitter frequency * mechanical jitter amplitude. Figure 3 shown.

[0009] However, the ideal linear output cannot be obtained through the mechanical dithering frequency deviation method, the start-up and recovery are slow, and the frequency tracking accuracy is low. Moreover, when the laser gyro works in a variable temperature environment, the mechanical dithering frequency decreases with the increase of temperature, and the mechanical dithering amplitude increases with the increase of temperature, and the dithering amplitude is unstable. Summary of the invention

[0010] In order to overcome the defects of the prior art, the technical problem to be solved by the present invention is to provide a digital jitter drive control circuit for the lock zone of a laser gyroscope, which can be closer to the ideal linear output, can quickly start oscillation and jitter recovery, has high frequency tracking accuracy, and the jitter amplitude is large enough and stable, which can improve the measurement accuracy of the gyroscope in a variable temperature environment.

[0011] The technical solution of the present invention is: the digital jitter drive control circuit of the laser gyro lock zone comprises a jitter drive control circuit, a jitter drive circuit, a jitter mechanism, a resonant cavity and a signal shaping circuit through which signals sequentially pass;

[0012] The jitter drive control circuit includes: an amplitude control loop, a frequency control loop, and a pulse width control circuit;

[0013] The mechanical jitter frequency deviation is obtained through four-fold frequency phase-locked counting, and the amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude. The frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency according to the frequency feedback signal. The pulse width control circuit compares the mechanical jitter amplitude and the real-time mechanical jitter frequency as reference objects, calculates the error according to the mechanical jitter amplitude benchmark, and then performs real-time control to compensate for the change.

[0014] A working method of a digital jitter drive control circuit in a laser gyro lock zone is also provided, comprising:

[0015] (I) Determine the static lock area of ​​the laser gyro;

[0016] (II) The laser gyro adds a dithering driving signal to convert the static lock area into a small dynamic lock area;

[0017] (III) The laser gyro adds a pseudo-random signal to eliminate the small dynamic lock area.

[0018] Another working method of a digital jitter drive control circuit in a laser gyro lock zone is also provided, which comprises the following steps:

[0019] (1) Obtain the mechanical jitter frequency deviation through quadruple frequency phase detection counting;

[0020] (2) The amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude;

[0021] (3) The frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency based on the frequency feedback signal;

[0022] (4) The pulse width control circuit compares the mechanical jitter amplitude and the real-time mechanical jitter frequency as reference objects, calculates the error based on the mechanical jitter amplitude benchmark, and then performs real-time control to compensate for the change.

[0023] The beneficial technical effects of the present invention are: the mechanical jitter frequency deviation is obtained by quadruple frequency phase-locked counting, the amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude; the frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency according to the frequency feedback signal; the pulse width control circuit compares the mechanical jitter amplitude and the real-time mechanical jitter frequency as reference objects, calculates the error according to the mechanical jitter amplitude benchmark, and then performs real-time control to compensate for the change; therefore, it can be closer to the ideal linear output, can quickly start oscillation and jitter recovery, has high frequency tracking accuracy, the jitter amplitude is large enough and stable, and can improve the measurement accuracy of the gyroscope in a variable temperature environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The region-locking effect of the laser gyro is shown.

[0025] Figure 2 The mechanical dithering frequency deviation method to solve the laser gyro lock area problem is shown.

[0026] Figure 3 Conventional laser gyro lock zone elimination is shown.

[0027] Figure 4 The generation of a sinusoidal alternating jitter is shown.

[0028] Figure 5 The ideal output and dynamic lock area of ​​the laser gyro are shown.

[0029] Figure 6 The working principle diagram of the digital jitter drive control circuit of the laser gyro lock zone according to the present invention is shown.

[0030] Figure 7 Laser gyro lock zone elimination according to the present invention is shown.

[0031] Figure 8 The working principle diagram of the fully digital phase-locked loop system according to the present invention is shown. DETAILED DESCRIPTION

[0032] like Figure 6 As shown, the digital jitter drive control circuit of the laser gyro lock zone includes a jitter drive control circuit, a jitter drive circuit, a jitter mechanism, a resonant cavity and a signal shaping circuit through which the signal passes in sequence;

[0033] like Figure 6 As shown in the dotted box in FIG, the jitter drive control circuit includes: an amplitude control loop, a frequency control loop, and a pulse width control circuit;

[0034] The mechanical jitter frequency deviation is obtained through four-fold frequency phase-locked counting, and the amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude. The frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency according to the frequency feedback signal. The pulse width control circuit compares the mechanical jitter amplitude and the real-time mechanical jitter frequency as reference objects, calculates the error according to the mechanical jitter amplitude benchmark, and then performs real-time control to compensate for the change.

[0035] The present invention obtains the mechanical jitter frequency deviation through four-fold frequency phase-lock counting, and the amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude; the frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency according to the frequency feedback signal; the pulse width control circuit compares the mechanical jitter amplitude and the real-time mechanical jitter frequency as reference objects, calculates the error according to the mechanical jitter amplitude reference, and then performs real-time control to compensate the change; therefore, it can be closer to the ideal linear output, can quickly start oscillation and jitter recovery, has high frequency tracking accuracy, the jitter amplitude is large enough and stable, and can improve the measurement accuracy of the gyroscope in a variable temperature environment.

[0036] Preferably, the circuit further comprises a frequency tracking and stabilization module, which provides a frequency feedback signal, and the module is a fully digital phase-locked loop system.

[0037] Preferably, the all-digital phase-locked loop system comprises two cascaded first-order all-digital phase-locked loops.

[0038] Preferably, if Figure 8 As shown, the all-digital phase-locked loop system includes: a first loop, a second loop, and an adder; the first loop includes a first XOR gate phase detector, a first K counter, a first ID counter, and a first N-dividing counter connected in sequence; the second loop includes a second XOR gate phase detector, a second K counter, a second ID counter, and a second N-dividing counter connected in sequence; the output of the second loop is inverted and enters the adder, the output of the first loop enters the adder, the output of the adder is connected to the first XOR gate phase detector, and the output of the first loop is used as a frequency feedback signal; wherein the K counter is a loop filter, the ID counter is an up-down counter, and the N-dividing counter and the up-down counter work together to form a digitally controlled oscillator.

[0039] A method for operating a digital jitter drive control circuit in a laser gyro lock zone is also provided, which comprises the following steps:

[0040] (I) Determine the static lock area of ​​the laser gyro (e.g. Figure 5 shown);

[0041] (II) The laser gyro adds a jitter drive signal to convert the static lock area into a small dynamic lock area (such as Figure 5 shown);

[0042] (III) The laser gyro adds a pseudo-random signal to eliminate the small dynamic lock area.

[0043] like Figure 7 As shown, another working method of the digital jitter drive control circuit of the laser gyro lock zone is also provided, which includes the following steps:

[0044] (1) Obtain the mechanical jitter frequency deviation through quadruple frequency phase detection counting;

[0045] (2) The amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude;

[0046] (3) The frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency based on the frequency feedback signal;

[0047] (4) The pulse width control circuit compares the mechanical jitter amplitude and the real-time mechanical jitter frequency as reference objects, calculates the error based on the mechanical jitter amplitude benchmark, and then performs real-time control to compensate for the change.

[0048] Preferably, in step (3), a frequency tracking and stabilization module is provided, which provides a frequency feedback signal, and the module is a fully digital phase-locked loop system. The key parameters of commonly used semi-analog devices will change due to the discreteness of components, and parasitic capacitance, device aging and temperature drift will cause the center frequency to fluctuate over a wide range. Therefore, a fully digital ADPLL is used in the present invention to overcome the above shortcomings.

[0049] Preferably, the step (3) comprises the following sub-steps:

[0050] (3.1) Input signal θ i Obtaining a first output signal θ0 through a first loop;

[0051] (3.2) Input signal θ i Obtaining a second output signal θ2 through a second loop;

[0052] (3.3) The second output signal θ2 is inverted and summed with the first output signal θ0 to form the intermediate output signal θ1;

[0053] (3.4) The intermediate output signal θ1 is injected into the first XOR gate phase detector;

[0054] (3.5) The frequency feedback signal is obtained through the first loop.

[0055] Verified by experimental data, the improved second-order ADPLL can improve its frequency locking accuracy, greatly reduce the steady-state error of the system, and improve the measurement accuracy of the system.

[0056] The purpose of increasing the mechanical jitter amplitude is to reduce the dynamic lock region, and the purpose of injecting pseudo-random noise is to eliminate the dynamic lock region.

[0057] The beneficial effects of the present invention are as follows:

[0058] (1) The mechanical jitter amplitude and mechanical jitter frequency are extracted from the mechanical jitter frequency deviation for reference comparison, and the input-output error is calculated to achieve the problem of stabilizing the mechanical jitter amplitude and mechanical jitter frequency. This solves the problem that the mechanical jitter amplitude decreases with increasing temperature and the mechanical jitter frequency decreases with increasing temperature.

[0059] (2) On the one hand, a fully digital phase-locked loop is used to replace the traditional semi-analog phase-locked loop; on the other hand, two first-order ADPLL systems are used to solve the problems of the steady-state error of the semi-analog phase-locked loop being affected by temperature and the poor frequency locking accuracy of the first-order ADPLL system, thereby ensuring the synchronous stability of the frequency and phase of the input and output.

[0060] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A digital jitter drive control circuit for a laser gyro lock zone, characterized in that: It includes a jitter drive control circuit, a jitter drive circuit, a jitter mechanism, a resonant cavity and a signal shaping circuit through which signals sequentially pass; The jitter drive control circuit includes: an amplitude control loop, a frequency control loop, and a pulse width control circuit; The mechanical jitter frequency deviation is obtained by quadruple frequency phase detection counting, and the amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude. The frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency according to the frequency feedback signal. The jitter amplitude is calculated by the mechanical jitter frequency deviation and the real-time mechanical jitter frequency, and the mechanical jitter amplitude reference is compared with the jitter amplitude to calculate the error, and then real-time control is performed to compensate for the jitter amplitude change. The circuit also includes a frequency tracking and stabilization module, which provides a frequency feedback signal. The module is a fully digital phase-locked loop system; The all-digital phase-locked loop system comprises two cascaded first-order all-digital phase-locked loops; The all-digital phase-locked loop system comprises: a first loop, a second loop, and an adder; the first loop comprises a first XOR gate phase detector, a first K counter, a first ID counter, and a first N-dividing counter connected in sequence; the second loop comprises a second XOR gate phase detector, a second K counter, a second ID counter, and a second N-dividing counter connected in sequence; the output of the second loop is inverted and enters the adder, the output of the first loop enters the adder, the output of the adder is connected to the first XOR gate phase detector, and the output of the first loop is used as a frequency feedback signal; wherein the K counter is a loop filter, the ID counter is an up-down counter, and the N-dividing counter and the up-down counter work together to form a digitally controlled oscillator.

2. The working method of the digital jitter drive control circuit of the laser gyro lock zone according to claim 1, characterized in that: It includes the following steps: (1) Obtain the mechanical jitter frequency deviation through quadruple frequency phase detection counting; (2) The amplitude control loop extracts the mechanical jitter frequency deviation and obtains the real-time mechanical jitter amplitude; (3) The frequency control loop extracts the mechanical jitter frequency and calculates the real-time mechanical jitter frequency based on the frequency feedback signal; (4) The jitter amplitude is calculated by the mechanical jitter frequency deviation and the real-time mechanical jitter frequency. The mechanical jitter amplitude reference and the jitter amplitude are compared to calculate the error, and then real-time control is performed to compensate for the jitter amplitude change.

3. The working method of the digital jitter drive control circuit of the laser gyro lock zone according to claim 2, characterized in that: The step (3) comprises the following sub-steps: (3.1) Input signal θ i Obtaining a first output signal θ0 through a first loop; (3.2) Input signal θ i Obtaining a second output signal θ2 through a second loop; (3.3) The second output signal θ2 is inverted and summed with the first output signal θ0 to form the intermediate output signal θ1; (3.4) The intermediate output signal θ1 is injected into the first XOR gate phase detector; (3.5) The frequency feedback signal is obtained through the first loop.

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