A laser frequency locking servo control method for a resonant optical gyroscope

Abstract

The present invention belongs to the technical field of optical gyroscopes and discloses a resonant optical gyroscope laser frequency locking servo control method. The method comprises the following steps: 1. Simplifying the transfer function of the resonant optical gyroscope laser frequency locking closed-loop control system to obtain a simplified control system state equation coefficient matrix; 2. Determining the laser frequency locking servo controller switching function based on the simplified control system state equation coefficient matrix; 3. Determining the control function of the variable structure servo controller and calculating the control parameter selection range that stabilizes the control system; and 4. Modeling and simulating the servo controller of the resonant optical gyroscope laser frequency locking closed-loop control system to obtain the optimal control parameters of the variable structure servo controller. The method solves the servo control requirements of the resonant optical gyroscope laser frequency locking control system, which require both excellent control performance and high anti-interference capability.

Description

Technical Field

[0001] The invention belongs to the technical field of optical gyroscopes, and in particular relates to a laser frequency locking servo control method for a resonant optical gyroscope. Background Art

[0002] Resonant optical gyroscopes offer a range of advantages, including high dynamic response, large dynamic range, immunity to electromagnetic interference, stable scale factor, and immunity to acceleration. They are one of the key development directions for inertial gyroscopes towards high precision and miniaturization. For laser frequency locking servo control of resonant optical gyroscopes, researchers currently generally use the traditional PID control method. This method is relatively simple, but suffers from a conflict between excellent control performance and high anti-interference capabilities. Specifically, when traditional PID control system designs pursue excellent control parameters, external interference introduced into the control system, such as shock, vibration, active mode hopping, and gyro rotation, can cause the laser frequency to unlock, rendering the gyro system inoperable. This fails to meet the servo control requirements of laser frequency locking for resonant optical gyroscopes, which require both excellent control performance and high anti-interference capabilities.

[0003] In order to improve the control performance and high anti-interference capability of the resonant optical gyroscope laser frequency locking servo controller, in October 2020, Li Suling and others published a laser frequency tracking and locking technology based on fuzzy PI control in the Journal of Nanchang University. Although this scheme can improve the locking accuracy of the resonant optical gyroscope laser frequency locking, its anti-interference capability is still insufficient. Summary of the Invention

[0004] The purpose of the present invention is to address the problems in the background technology and propose a resonant optical gyroscope laser frequency locking servo control method, which solves the servo control requirements of the resonant optical gyroscope laser frequency locking control system, while having excellent control performance and high anti-interference ability.

[0005] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions to achieve it.

[0006] A laser frequency locking servo control method for a resonant optical gyroscope, the method comprising:

[0007] Step 1, simplifying the transfer function of the laser frequency locked closed-loop control system of the resonant optical gyroscope to obtain a simplified control system state equation coefficient matrix;

[0008] Step 2: Determine the laser frequency locking servo controller switching function based on the simplified control system state equation coefficient matrix;

[0009] Step 3: Determine the control function of the variable structure servo controller and calculate the range of control parameters that make the control system stable;

[0010] Step 4: Model and simulate the servo controller of the laser frequency locked closed-loop control system of the resonant optical gyroscope to obtain the optimal control parameters of the variable structure servo controller.

[0011] The characteristics and further improvements of the technical solution of the present invention are:

[0012] (1) In step 1, in the resonant optical gyroscope, the light generated by the tunable semiconductor laser is modulated by the Y waveguide and then incident on the optical resonant cavity through the coupler to generate resonant light. The resonant light is emitted through the coupler to the photodetector PD for photoelectric conversion. The signal is demodulated to obtain a control system error signal. The error signal acts on the laser through the servo controller to form a laser frequency locked closed-loop control circuit.

[0013] (2) The transmission of the frequency deviation of the optical Sagnac resonance system is simplified to a proportional link transmission with a coefficient of K, where the external disturbance to the optical Sagnac resonance system is expressed as f M Represented; the photoelectric conversion process will isolate the signal from direct current, which can be equivalent to a first-order high-pass filter, represented by the HPF function; the demodulation process performs low-pass filtering on the signal, which can be represented by a first-order low-pass filter LPF function; the laser integrates the frequency deviation u, which can be represented as the integral link 1 / s; the control system state equation coefficient matrix is obtained.

[0014] (3) The control system state equation coefficient matrix is as shown in formula (1), where x1 = e, are system state variables, a1, a2, and b1 are constants determined by the system transfer function;

[0015]

[0016] (4) In step 2, the switching function of the laser frequency locking servo controller is determined according to the simplified control system state equation coefficient matrix, as shown in formula (2), where s is the condition judgment function and c1 is the parameter that determines the characteristics of the condition judgment function s;

[0017]

[0018] (5) In step 3, the control function of the variable structure servo controller is determined, as shown in formula (3), where α and β are proportional coefficients, u is the control signal, and the control signal is the frequency deviation u;

[0019] u=ψ1e,

[0020] (6) In step 3, the range of control parameters that stabilize the control system is calculated to be:

[0021] To stabilize the control system, the switching function needs to meet the reaching condition, as shown in formula (4). δ is an arbitrary small positive number, and considering that the system transfer function has non-negative real roots, formulas (1), (2), and (3) are substituted into formula (4) to obtain the range of control parameters that meet the system stability condition, as shown in formula (5):

[0022]

[0023]

[0024] (7) In step 4, the servo controller is modeled and simulated using Simulink software. By analyzing the step response characteristics of the system, the control parameters are optimized to obtain the optimal control parameters of the variable structure servo controller.

[0025] Advantages of the present invention: The present invention addresses the current inability of resonant optical gyroscope laser frequency locking servo control to meet the system's servo control requirements for both excellent control performance and strong anti-interference capabilities. This invention proposes a resonant optical gyroscope laser frequency locking variable structure servo control method that simultaneously achieves high control accuracy and strong anti-interference capabilities. The present invention's method significantly improves the control accuracy and anti-interference capabilities of the resonant optical gyroscope laser frequency locking servo control. To date, no reports have been reported on the use of this method to achieve resonant optical gyroscope laser frequency locking servo control. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Schematic diagram of the laser frequency locking system for a resonant optical gyroscope;

[0027] Figure 2 It is a schematic diagram of the control system signal transmission model;

[0028] Figure 3 is the variable structure servo controller model;

[0029] Explanation of the accompanying symbols: 1 is a servo controller; 2 is an integral function; 3 is a proportional function; 4 is an external interference signal; 5 is a high-pass filter function, 6 is a low-pass filter function; 7 is a system error signal; 8 is a control signal. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is described in detail below with reference to the accompanying drawings.

[0031] Example 1

[0032] This embodiment provides a resonant optical gyroscope laser frequency locked variable structure servo control method with high control accuracy and strong anti-interference ability. Figure 1As shown, the light generated by the tunable semiconductor laser is modulated by the Y waveguide and then incident on the optical resonant cavity through the coupler to generate resonant light. The resonant light is emitted through the coupler to the photodetector PD for photoelectric conversion. The signal is demodulated to obtain a control system error signal. The error signal acts on the laser through the servo controller 1 to form a laser frequency locked closed-loop control circuit.

[0033] In order to explain the design process of the closed-loop control system servo controller, the transfer function of the resonant optical gyroscope laser frequency locked closed-loop control system is simplified, as shown in the following example: Figure 2 As shown in the figure, the transmission of the frequency deviation of the optical Sagnac resonance system is simplified to the proportional link transmission with a coefficient of K3, where the external disturbance to the optical Sagnac resonance system is represented by f M Represented as 4, due to the existence of disturbance 4, the transfer function of the control system will change in actual work; the photoelectric conversion process will isolate the signal from the DC, which can be equivalent to a first-order high-pass filter, represented by HPF function 5; the demodulation process performs low-pass filtering on the signal, which can be represented by a first-order low-pass filter LPF function 6; the laser integrates the frequency deviation u, which can be represented as an integral link 2; the system state equation coefficient matrix is obtained as formula (1), where x1 = e, are system state variables, and a1, a2, and b1 are constants determined by the system transfer function.

[0034]

[0035] Example 2

[0036] This embodiment further illustrates the specific design simulation method of the present invention:

[0037] According to the system transfer function, a servo controller switching function is designed that meets the requirements of the resonant optical gyroscope laser frequency locked closed-loop control system as the controlled object, as shown in formula (2), where s is the condition judgment function and c1 is the parameter that determines the characteristics of the condition judgment function s;

[0038]

[0039] Design the control function of the variable structure servo controller, as shown in formula (3), where α and β are proportional coefficients and u is the control signal. To stabilize the control system, the switching function needs to meet the arrival condition, as shown in formula (4), where δ is an arbitrary small positive number and considering that the system transfer function has non-negative real roots, substitute formulas (1), (2) and (3) into formula (4) to obtain the range of control parameters that meet the system stability condition, as shown in formula (5).

[0040] u=ψ1e,

[0041]

[0042]

[0043] Use simulink software to model and simulate the servo controller. By analyzing the system step response characteristics, the control parameters are optimized. The servo controller model based on the variable structure control law is as follows: Figure 3 As shown, the system error signal input 7 automatically switches the control parameters through the conditional function to form a control signal 8, and the control signal 8 acts on the laser to form a laser frequency locked closed-loop control circuit.

[0044] The present invention addresses the current inability of resonant optical gyroscope laser frequency locking servo control to meet the system's requirements for both excellent control performance and strong anti-interference capability. A variable-structure servo control method for resonant optical gyroscope laser frequency locking is proposed, which simultaneously achieves high control accuracy and strong anti-interference capability. This method significantly improves the control accuracy and anti-interference capability of the resonant optical gyroscope laser frequency locking servo control.

Claims

1. A laser frequency locking servo control method for a resonant optical gyroscope, characterized in that: The method comprises: Step 1: Simplify the transfer function of the resonant optical gyroscope laser frequency locked closed-loop control system to obtain a simplified control system state equation coefficient matrix; simplify the transmission of the optical Sagnac resonant system frequency deviation to a proportional link transmission with a coefficient of K, where the external disturbance to the optical Sagnac resonant system is expressed as Representation; the photoelectric conversion process will block the signal from direct current, which can be equivalent to a first-order high-pass filter, represented by the HPF function; the demodulation process performs low-pass filtering on the signal, which can be represented by a first-order low-pass filter LPF function; the laser integrates the frequency deviation u, which can be represented as the integral link 1 / s; the control system state equation coefficient matrix is obtained; Step 2: Determine the laser frequency locked servo controller switching function based on the simplified control system state equation coefficient matrix; In step 2, determine the laser frequency locked servo controller switching function based on the simplified control system state equation coefficient matrix, as shown in formula (2), where is the conditional judgment function, To determine the condition function Parameters of the characteristics; （2） Step 3: Determine the control function of the variable structure servo controller and calculate the range of control parameters that make the control system stable. In step 3, determine the control function of the variable structure servo controller, as shown in formula (3), 、 is the proportionality coefficient, is a control signal, and the control signal is a frequency deviation u; （3） Step 4: Model and simulate the servo controller of the laser frequency locked closed-loop control system of the resonant optical gyroscope to obtain the optimal control parameters of the variable structure servo controller.

2. The laser frequency locking servo control method for a resonant optical gyroscope according to claim 1, characterized in that: In step 1, in the resonant optical gyroscope, the light generated by the tunable semiconductor laser is modulated by the Y waveguide and then incident on the optical resonant cavity through the coupler to generate resonant light. The resonant light is emitted through the coupler to the photodetector PD for photoelectric conversion. The signal is demodulated to obtain a control system error signal. The error signal acts on the laser through the servo controller to form a laser frequency locked closed-loop control loop.

3. The laser frequency locking servo control method for a resonant optical gyroscope according to claim 1, characterized in that: The control system state equation coefficient matrix is as shown in formula (1), where , is the system state variable, 、 、 is a constant determined by the system transfer function; （1）。 4. The laser frequency locking servo control method for a resonant optical gyroscope according to claim 3, characterized in that: In step 3, the range of control parameters that stabilize the control system is calculated to be: To stabilize the control system, the switching function needs to meet the arrival condition, as shown in formula (4): is an arbitrary small positive number, and considering that the system transfer function has non-negative real roots, substitute formulas (1), (2), and (3) into formula (4) to obtain the range of control parameters that meet the system stability conditions as shown in formula (5): （4） （5）。 5. The laser frequency locking servo control method for a resonant optical gyroscope according to claim 4, characterized in that: In step 4, the servo controller is modeled and simulated using Simulink software. By analyzing the system step response characteristics, the control parameters are optimized to obtain the optimal control parameters of the variable structure servo controller.

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