CN105698820B - A kind of laser gyro cavity translatory mirror shakes deformation active compensation device - Google Patents

Abstract

An active compensation device for vibration and deformation of a laser gyro cavity translation mirror, including an error processing circuit, an analog-to-digital converter, a controller, a digital-to-analog converter, a phase-shifting circuit, a multiplier, and a summation circuit, and the light intensity signal output by the laser gyro Or the quadrature counting signal is processed to obtain the error signal representing the jitter modulation. The controller adjusts the amplitude and phase of the jitter feedback signal according to the error signal to obtain the jitter deformation active compensation signal. The jitter deformation active compensation signal and the cavity length control voltage are superimposed on the laser The cavity translation mirror of the gyroscope is controlled to compensate the laser gyro cavity length change caused by thermal expansion and thermal deformation and the radial deformation of the cavity translation mirror caused by mechanical vibration, thereby reducing or eliminating the gyro cavity length change caused by mechanical vibration and improving the The accuracy of the laser gyro. The invention does not change the existing structure of the laser gyroscope, only actively compensates the radial deformation of the cavity translation mirror caused by mechanical vibration through electronic circuit and signal processing, and has low implementation cost.

Description

An Active Compensation Device for Vibration and Deformation of Laser Gyro Cavity Translating Mirror

technical field

The invention relates to a laser gyroscope, in particular to an active compensation device for vibration and deformation of a laser gyroscope cavity translation mirror, which is used to reduce or eliminate the radial cavity length change of the gyroscope caused by mechanical vibration.

Background technique

Ring laser gyro has a series of advantages such as wide dynamic range, good linearity of scale factor, fast start-up, and insensitivity to acceleration. It is an ideal component of strapdown inertial system and is widely used in navigation, aviation, aerospace and land and other fields.

The laser gyroscope has a lock-up phenomenon, and the lock-up can be eliminated by using mechanical jitter bias frequency. A typical mechanically dithered frequency-biased laser gyro has a triangular or square configuration with three or four mirrors. Figure 1 is a schematic diagram of the structure of a mechanically dithered frequency-biased laser gyro in a square configuration. Two movable mirrors 2, 3, two fixed mirrors 4, 5 and a square glass-ceramic cavity 1 form a laser resonant cavity, and two beams are generated in the cavity. Lasers running in opposite directions. The outer sides of the two movable mirrors 2 and 3 are bonded with piezoelectric ceramics (PZT). Changing the voltage on the piezoelectric ceramics can produce telescopic movement, which drives the movable mirrors 2 and 3 to move in the axial direction, so that the cavity length of the gyro resonant cavity occurs Variety. The movable mirror, piezoelectric ceramics and their components form a cavity translation mirror (or a cavity length control mechanism, a path length control mechanism, and a frequency stabilization device). During the operation of the laser gyro, the total cavity length will change due to the thermal expansion and thermal deformation of the cavity. In order to stabilize the laser frequency, it is necessary to use a cavity translation mirror to stabilize the total cavity length.

The photodiode 7 is bonded to the light-combining prism of the fixed mirror 4 for outputting two orthogonal gyro counting signals A and B, and the photodiode 8 is bonded to the fixed mirror 5 for outputting the light intensity signal LIM, which can be used It can be used for light intensity monitoring or as a feedback input for cavity length control circuit. The shaking wheel 6 is installed in the center of the glass-ceramic cavity 1, and the spokes of the shaking wheel are pasted with PZT sheets. Driven by the PZT sheets, the shaking wheel drives the cavity to produce small and rapid alternating vibrations, thereby adding a positive and negative to the gyroscope. Alternating jitter bias frequency eliminates gyro lock-in effect.

While the vibrating wheel drives the cavity body to vibrate slightly and rapidly alternately, the cavity translation mirror also produces the same movement, which is manifested as the cavity translation mirror being subjected to alternating inertial force. The amplitude θ of the gyro shake is usually 200-600 arc seconds, the shake frequency f is 300Hz-1000Hz, the shake angular acceleration a=θ·(2πf) ² is very large, and the tangential acceleration at the cavity translation mirror 3 is also very large, correspondingly The cavity translation mirror will bear a large alternating inertial force. Because the stiffness of the cavity translation mirror is smaller than that of the glass-ceramic cavity 1, and the stiffness of its components is also different, the cavity translation mirror will inevitably produce tangential deformation X, and at the same time, due to some non-ideal factors of the cavity translation mirror, it will also cause radial Deformation Y. The radial deformation modulates the cavity length of the resonator, which leads to a decrease in frequency stabilization accuracy and affects the performance of the gyroscope. The output light intensity LIM of the gyroscope and the amplitude of the quadrature counting signals A and B will be modulated, and the modulation frequency is related to the jitter frequency. The modulation amplitude is related to the radial deformation, the greater the radial deformation, the greater the amplitude modulation. The mechanical jitter feedback signal U _d and the gyro output A under jitter modulation are shown in Figure 2. It can be seen that the amplitude of the gyro output A is modulated by the jitter, and the gyro output B is similar. At the same time, the light intensity signal LIM is also modulated by the jitter. Jitter modulation results in degraded gyro performance.

At present, when the laser gyroscope works normally, it has a supporting cavity length control circuit (frequency stabilization circuit), which is used to compensate the change of the cavity length caused by thermal expansion and thermal deformation. The specific schematic diagram of the cavity length control circuit is shown in Figure 3. The light intensity LIM output by the photodiode is input to the cavity length control circuit 1, and the cavity length control circuit 1 outputs the corresponding cavity length control voltage V _PLC according to the change of the light intensity signal LIM. Amplifier 2 is amplified and added to the cavity translation mirror to compensate the change of gyroscope cavity length caused by thermal deformation. However, since the frequency response of the cavity length control circuit is generally much lower than the mechanical jitter frequency, the radial deformation of the cavity translation mirror and the gyro cavity length caused by mechanical jitter are dynamically changed at the jitter frequency, so the cavity length control circuit cannot be used to control the mechanical vibration. The radial deformation of the cavity translation mirror and the change of the gyroscope cavity length are compensated; in order to reduce the deformation of the cavity translation mirror caused by mechanical vibration and its influence on the performance of the gyro, the general practice in the prior art is to optimize the structural design of the cavity translation mirror, increase The structural stiffness of the cavity translation mirror is difficult in that the existing structure of the gyroscope needs to be changed and the cost is high.

Contents of the invention

The purpose of the present invention is to provide an active compensation device for vibration and deformation of the laser gyroscope cavity translation mirror, which can actively compensate the radial deformation of the cavity translation mirror caused by mechanical jitter through electronic circuits and signal processing on the basis of the existing structure of the laser gyroscope. Compensate, reduce or eliminate the change of gyroscope cavity length caused by mechanical vibration, so as to improve the accuracy of laser gyroscope.

The technical solution adopted for realizing the present invention is:

The active compensation device for vibration and deformation of the laser gyro cavity translation mirror includes a cavity length control circuit, and is characterized in that it also includes: an error processing circuit (10), an analog-to-digital converter (20), a controller (30), a digital-to-analog converter ( 40), phase shifting circuit (50), multiplier (60), summation circuit (70); error processing circuit (10) receives the light intensity signal of laser gyro, and the output error voltage is imported through analog-to-digital converter (20) Controller (30); the mechanical jitter feedback signal is phase-shifted by the phase-shifting circuit (50) and then multiplied by the multiplier (60) with the compensation control quantity output by the controller (30) through the digital-to-analog converter (40) The jitter deformation active compensation signal with adjustable amplitude and phase, the signal is superimposed with the original cavity length control voltage to control the cavity translation mirror of the laser gyroscope, and compensates for the cavity length change of the laser gyroscope caused by thermal expansion and thermal deformation. At the same time, the radial deformation of the cavity translation mirror caused by the mechanical vibration is compensated, thereby reducing or eliminating the change of the gyroscope cavity length caused by the mechanical vibration.

The error processing circuit (10) processes the output light intensity of the gyroscope or the quadrature counting signal to obtain an error voltage.

Adjusting the amplitude and phase of the jitter deformation active compensation signal to minimize the error voltage can reduce or eliminate the radial deformation of the cavity translation mirror and the change of the gyroscope cavity length caused by mechanical jitter.

The controller (30) is a built-in controller of the laser gyro, or an additional controller.

The error processing circuit (10) is composed of a band-pass filter (11) and an AC/DC conversion circuit (12), or an envelope detector (13) and an AC/DC conversion circuit (13).

The controller (30) is a single-chip microcomputer, FPGA or DSP.

The AC/DC conversion circuit (12) is an AC/DC conversion circuit composed of AD736 chips.

The phase shifting circuit (50) is a multi-terminal feedback all-pass filter including operational amplifiers, resistors and capacitors, and the phase shifting angle is changed by changing the values of the resistors and capacitors.

The envelope detection circuit (13) is a circuit including an amplitude modulation resistor and an amplitude modulation capacitor.

The advantages of the present invention are:

The present invention does not change the existing structure of the laser gyroscope, only actively compensates the radial deformation of the cavity translation mirror caused by mechanical vibration through electronic circuits and signal processing, improves the accuracy of the laser gyroscope, and at the same time has low implementation cost.

Description of drawings

Figure 1 is a schematic diagram of the structure of a mechanically shaken frequency-biased laser gyroscope in a square configuration.

Figure 2 is a waveform diagram of the mechanical jitter feedback signal and the gyroscope output count signal A under jitter modulation.

FIG. 3 is a schematic diagram of a laser gyro cavity length control circuit in the background technology.

Fig. 4 is a structural block diagram of the first example of the laser gyro cavity translation mirror vibration deformation active compensation device of the present invention.

Fig. 5 is a structural block diagram of a second example of an active compensation device for vibration and deformation of a laser gyro cavity translation mirror according to the present invention.

FIG. 6 is a circuit schematic diagram of a specific embodiment of the AC/DC conversion circuit of the present invention.

Fig. 7 is a schematic circuit diagram of a specific embodiment of the phase shifting circuit of the present invention.

FIG. 8 is a circuit schematic diagram of a specific embodiment of the multiplier circuit of the present invention.

FIG. 9 is a circuit schematic diagram of a specific embodiment of the envelope detection circuit of the present invention.

Fig. 10 is a schematic circuit diagram of a specific embodiment of the summation circuit of the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with specific embodiments and accompanying drawings.

As shown in Figure 4, the first example of the active compensation device for vibration and deformation of the laser gyroscope cavity translation mirror of the present invention includes an error processing circuit 10, an analog-to-digital converter 20, a controller 30, a digital-to-analog converter 40, a phase-shifting circuit 50, and a multiplier 60. A summation circuit 70. The error processing circuit 10 includes a band-pass filter 11 and an AC/DC conversion circuit 12 . The controller 20 is a single-chip microcomputer, FPGA or DSP, and the existing controller in the supporting circuit of the laser gyro can be used, or an additional controller can be added. The analog-to-digital converter 20 is preferably an analog-to-digital conversion chip with a resolution of 10 bits or more and a conversion rate greater than 100 times per second. The digital-to-analog converter 40 is preferably a digital-to-analog conversion chip with a resolution of 10 bits or more and a conversion rate greater than 100 times per second. The cavity length control circuit 1 and the voltage amplifier 2 in Fig. 4 belong to the supporting circuits required for the normal operation of the laser gyroscope, and can be any existing circuits that can meet the cavity length control requirements.

In this embodiment, the photodiode of the laser gyro detects the light intensity of the laser gyro and outputs a light intensity signal LIM, which is input to the cavity length control circuit 1 and the error processing circuit 10 at the same time. After one light intensity signal is input to the cavity length control circuit 1, a cavity length control value V _PLC is formed, which is used to compensate the cavity length change caused by the thermal expansion and thermal deformation of the laser gyroscope. The other light intensity signal LIM is input to the band-pass filter circuit 11 of the error processing circuit 10. The center frequency of the band-pass filter must be set close to the frequency of the mechanical dithering, and the output error signal err reflects the amplitude modulation of the mechanical dithering on the light intensity. , the error signal is converted into a DC error voltage _Verr by the AC/DC conversion circuit 12 . The DC error voltage V _err is converted into a digital signal by the analog-to-digital converter 20 and input to the controller 30. The controller calculates the active compensation control value V _c according to the size of the error voltage, and the active compensation control value V _c is converted by digital-to-analog conversion device 40 output.

The jitter feedback signal U _d representing the amplitude and frequency of the mechanical jitter is passed through the phase-shifting circuit 50 to shift the angle θ to obtain U _dθ , and the phase-shifted jitter feedback signal U _dθ is sent to the multiplier 60 to be multiplied by the active compensation control amount V _c The vibration deformation active compensation signal U _COMP of the cavity translation mirror is obtained. The multiplier 60 outputs U _COMP =S U _dθ V _c , where S is the scaling factor of the multiplier, so changing the compensation control amount V _c can change the amplitude of the jitter deformation active compensation signal U _COMP and change the phase shifting circuit The phase angle θ can change the phase of the jitter deformation active compensation signal U _COMP . The method of determining the phase shift angle θ of the phase shift circuit is as follows: keep the compensation control amount V _c unchanged, correspondingly the amplitude of the jitter deformation active compensation signal U _COMP superimposed on the cavity translation mirror remains unchanged, and change the value of the phase shift angle θ, The angle θ that makes the error voltage V _err the smallest is the required phase shift angle.

The cavity length control voltage V _PLC and the jitter deformation active compensation signal U _COMP are summed by the summation circuit 70, amplified by the voltage amplifier 2, and then added to the cavity translation mirror together, wherein the cavity length control voltage V _PLC compensates the cavity length caused by thermal expansion and thermal deformation The active compensation signal U _COMP compensates for the radial deformation of the cavity translation mirror and the change of the gyroscope cavity length caused by mechanical jitter.

According to the vibration deformation compensation process of the laser gyro cavity translation mirror as mentioned above, it can be seen that the size of the error voltage _Verr is directly related to the size of the active compensation control amount _Vc , so the purpose of the controller is to calculate the active compensation control amount The size of V _c , so that the error voltage V _err is the smallest. An optional control strategy is: fix an incremental voltage value ΔV, the controller outputs an initial active compensation control variable V _c , and then increase the active compensation control variable V _c in the next control cycle by K·ΔV, where K is initially The value is 1, and then the controller detects the changed error voltage V _err : if V _err becomes smaller, K remains unchanged; otherwise, if V _err becomes larger, the sign of K is changed, and this process can be repeated to find the control that minimizes V _err Voltage V _c , at this time, the active compensation signal minimizes the influence of mechanical vibration on the radial deformation of the cavity translation mirror and the length of the gyro cavity.

As shown in Figure 5, the second example of the active compensation device for vibration and deformation of the laser gyroscope cavity translation mirror of the present invention includes an error processing circuit 10, an analog-to-digital converter 20, a controller 30, a digital-to-analog converter 40, a phase-shifting circuit 50, and a multiplier 60. A summation circuit 70. The error processing circuit 10 includes an envelope detection circuit 13 and an AC/DC conversion circuit 12 . The controller 20 is a single-chip microcomputer, FPGA or DSP, and the existing controller in the supporting circuit of the laser gyro can be used, or an additional controller can be added. The analog-to-digital converter 20 is preferably an analog-to-digital conversion chip with a resolution of 10 bits or more and a conversion rate greater than 100 times per second. The digital-to-analog converter 40 is preferably a digital-to-analog conversion chip with a resolution of 10 bits or more and a conversion rate greater than 100 times per second. The cavity length control circuit 1 and the voltage amplifier 2 in Fig. 5 belong to the supporting circuits required for the normal operation of the laser gyroscope, and can be any existing circuits that can meet the cavity length control requirements.

In this embodiment, the laser gyro light intensity signal LIM is input to the cavity length control circuit 1 to form a cavity length control voltage V _PLC for compensating the cavity length change caused by the thermal expansion and thermal deformation of the laser gyro. The laser gyro quadrature signal A (or B) is input to the envelope detection circuit 13 of the error processing circuit 10, and the envelope detection circuit 13 outputs the error signal err, which reflects the amplitude modulation of the light intensity by the mechanical jitter, and the error signal is composed of AC/DC The conversion circuit 12 converts it into a DC error voltage V _err . The DC error voltage V _err is converted into a digital signal by the analog-to-digital converter 20 and input to the controller 30. The controller 30 uses the same method as in Embodiment 1 to obtain the jitter deformation active compensation signal U _COMP , and then compares it with the cavity length control voltage V _PLC superimposed to form the final control amount to control the cavity translation mirror of the laser gyroscope.

As shown in FIG. 6 , it is a schematic circuit diagram of a specific embodiment of the AC/DC conversion circuit 12 of the present invention: in this embodiment, the AC/DC conversion circuit is completed by an effective value chip of the model AD736. The output error signal err of bandpass filter 11 or envelope detector 13 is input to pin 2 of AD736 chip, pin 7 of the chip is connected to power supply +15V, pin 4 is connected to power supply -15V, pin 1 and pin 8 are grounded , Pin 5 is connected to pin 4 through a capacitor C _av , and pin 6 of the chip outputs V _err as a DC voltage, whose value is equal to the effective value of input err, reflecting the amplitude modulation of mechanical jitter on light intensity.

As shown in FIG. 7 , it is a schematic circuit diagram of a specific embodiment of the phase shifting circuit of the present invention: in this embodiment, the phase shifting circuit is a multi-terminal feedback all-pass filter composed of an operational amplifier, a resistor and a capacitor. In the figure, the resistance value of the resistor R2 is 1/4 of the resistance value of the resistor R1, the resistance values of the resistor R3 and the resistor R4 are the same, which are twice the resistance value of the resistor R1; the capacitance values of the capacitors C1 and C2 are the same. Changing the resistance value of the resistor or the capacitance value of the capacitor in the circuit can change the size of the phase shift angle θ. During the working process of the jitter deformation compensation device of the laser gyro cavity translation mirror, the phase shift angle θ of the above-mentioned phase shift circuit can be corrected once when the device is first powered on and initialized, or it can be initialized every time it is powered on automatically adjusted by the controller. In the case of automatic adjustment by the controller, it is necessary to use a digital potentiometer instead of a resistor to ensure that the controller can adjust the phase shift angle θ.

As shown in Figure 8, it is the circuit schematic diagram of the specific embodiment of the multiplier of the present invention: in this embodiment, the multiplier adopts the multiplier chip that the model is AD633 to form; Pin 1 and pin 3 of the chip input active compensation The control variable V _c and the jitter feedback signal U _dθ after phase shifting; the pin 2, pin 4 and pin 6 of the chip are directly grounded; the pin 5 of the chip is connected to the power supply -15V, and grounded through a 0.1uF filter capacitor ; Pin 8 of the chip is connected to the power supply +15V, and grounded through a 0.1uF filter capacitor; the output pin 7 of the chip outputs signal U _COMP =0.1·U _dθ ·V _c .

As shown in Figure 9, it is a schematic circuit diagram of a specific embodiment of the envelope detection circuit of the present invention: in this embodiment, the envelope detection circuit is composed of a diode D1, a filter capacitor C1, a filter resistor R1 and an isolation capacitor C2; The input end of the circuit is connected to the laser gyro quadrature signal A or B, and the output end of the circuit is the error signal err, which reflects the amplitude modulation of the light intensity by the mechanical jitter. Select C1 and R1 to allow the amplitude modulation signal to pass, while the carrier signal higher than the jitter frequency is filtered out, and C2 is used to isolate the DC signal.

As shown in Figure 10, it is the circuit schematic diagram of the specific embodiment of the summation circuit of the present invention: in this embodiment, the resistance values of the resistors R1, R2, R3, R4 are the same, and the cavity length control voltage V _PLC is connected to the resistor R1 , The jitter deformation active compensation signal U _COMP is connected to the resistor R2. The output V _OUT is the sum of V _PLC and U _COMP .

In summary, since the present invention adopts the active compensation method, the light intensity signal or the quadrature counting signal output by the laser gyro is processed to obtain an error signal representing jitter modulation, and the controller adjusts the amplitude and frequency of the jitter feedback signal according to the error signal. The phase obtains the jitter deformation active compensation signal, and the jitter deformation active compensation signal is superimposed with the existing cavity length control voltage to control the cavity translation mirror of the laser gyroscope together, while compensating for the laser gyroscope cavity length change caused by thermal expansion and thermal deformation. Compensate the radial deformation of the cavity translation mirror caused by mechanical jitter, thereby reducing or eliminating the change of gyroscope cavity length caused by mechanical jitter, and improving the accuracy of the laser gyroscope; the present invention does not change the existing structure of the laser gyroscope, only through electronic circuits and The signal processing actively compensates the radial deformation of the cavity translation mirror caused by mechanical jitter, and the implementation cost is low.

Claims (9)

1. A laser gyroscope cavity translation mirror shake deformation active compensation device, comprising a cavity length control circuit, is characterized in that: also includes: error processing circuit (10), analog-to-digital converter (20), controller (30), digital analog converter (40), phase shifting circuit (50), multiplier (60), and summation circuit (70); the error processing circuit (10) receives the light intensity signal of the laser gyroscope, and the output error voltage passes through the analog-to-digital converter ( 20) into the controller (30); the mechanical jitter feedback signal is phase-shifted by the phase-shifting circuit (50) and the compensation control output output by the controller (30) through the digital-to-analog converter (40) is passed through the multiplier (60 ) is multiplied to obtain an active compensation signal for jitter deformation with adjustable amplitude and phase. This signal is superimposed with the existing cavity length control voltage to control the cavity translation mirror of the laser gyro. The radial deformation of the cavity translation mirror caused by mechanical vibration is compensated while the cavity length changes, thereby reducing or eliminating the change in the cavity length of the gyroscope caused by mechanical vibration. 2. The active compensation device for vibration and deformation of the laser gyro cavity translation mirror according to claim 1, characterized in that: the error processing circuit (10) processes the output light intensity of the gyro or the quadrature count signal to obtain an error voltage. 3. The laser gyroscope cavity translation mirror vibration deformation active compensation device according to claim 1, characterized in that: adjusting the amplitude and phase of the vibration deformation active compensation signal to minimize the error voltage can reduce or eliminate the cavity translation mirror caused by mechanical vibration Radial deformation and gyro cavity length variation. 4. The active compensation device for vibration and deformation of the laser gyroscope cavity translation mirror according to claim 1, characterized in that: the controller (30) is a built-in controller of the laser gyroscope, or an additional controller. 5. The laser gyro cavity translation mirror vibration and deformation active compensation device according to any one of claims 1 to 4, characterized in that: the error processing circuit (10) is composed of a bandpass filter (11) and an AC/DC conversion circuit (12), or consists of an envelope detector (13) and an AC/DC conversion circuit (12). 6. The active compensation device for vibration and deformation of the laser gyro cavity translation mirror according to any one of claims 1 to 4, characterized in that: the controller (30) is a single-chip microcomputer, FPGA or DSP. 7. The active compensation device for vibration and deformation of the laser gyroscope cavity translation mirror according to claim 5, characterized in that: the AC/DC conversion circuit (12) is an AC/DC conversion circuit composed of AD736 chips. 8. The active compensation device for vibration and deformation of the laser gyro cavity translation mirror according to any one of claims 1 to 4, characterized in that: the phase shifting circuit (50) is a multi-terminal feedback all-pass including operational amplifiers, resistors and capacitors Filter, by changing the value of the resistor and capacitor to change the phase shift angle. 9. The active compensation device for vibration and deformation of the laser gyro cavity translation mirror according to claim 5, characterized in that: the envelope detector (13) is a circuit including an amplitude modulation resistor and an amplitude modulation capacitor.