A high-precision fiber-optic gyroscope temperature drift monitoring and error suppression system and method

Abstract

The application relates to a high-precision fiber-optic gyroscope temperature drift monitoring and error suppression system and method, which is characterized in that a reference gyroscope is used for noise output; a monitoring gyroscope is used for monitoring the zero bias mean value; the two gyroscopes are arranged on the same carrier plane and the sensitive axes are parallel; a rotating heating cover is arranged outside the two gyroscopes and is composed of two hemispheres, is supported on the fixed carrier through a support point at the top of the two hemispheres, and realizes the free rotation of the heating cover around the normal line of the carrier plane along the clockwise and counterclockwise directions; the rotating heating cover is composed of equidistant spherical zone heating pieces in the latitude direction, heating resistors are arranged on the heating pieces; a comparator is used for collecting the output signals of the reference gyroscope and the monitoring gyroscope and performing differential operation; a temperature compensation unit adopts a neural network training model, realizes the determination and addressing of the heating resistance conduction, outputs the heating temperature and the heating time, and realizes the rotating heating control of the rotating heating cover. The application better realizes the temperature drift monitoring and error suppression of the high-precision fiber-optic gyroscope.

Description

Technical Field

[0001] This invention belongs to the field of fiber optic gyroscope technology, specifically relating to a high-precision fiber optic gyroscope temperature drift monitoring technology and error suppression method and system. Background Technology

[0002] With the widespread application of fiber optic gyroscopes, the accuracy requirements for gyroscopes are increasing daily, especially in certain high-reliability and high-precision applications. Because fiber optic gyroscopes utilize fiber optic loops, they have a relatively large spatial dimension. When the ambient temperature changes, the loop exhibits a certain degree of temperature field inhomogeneity, resulting in thermal drift. The most significant drift is gyroscope drift caused by the suction thermal effect, i.e., suction error. In recent years, the temperature-dependent zero bias of fiber optic gyroscopes has become a major factor limiting their further advancement in high-precision applications. To effectively eliminate these errors, besides improving the symmetry and precision of the loop winding, an effective method is to eliminate temperature field inhomogeneity. This can be achieved by using temperature control combined with a rotating heating shroud, "stirring" the spatial thermal field to achieve temperature uniformity. The advantage is its simplicity; the disadvantage is the large size of the mechanical actuator and the inherent lag in operation control, resulting in an unavoidable time delay. This means that a portion of the temperature gradient still acts on the gyroscope, causing drift. Therefore, it is necessary to suppress or eliminate the temperature drift caused by this lag.

[0003] Because high-precision fiber optic gyroscopes typically have large coil sizes (hundreds of millimeters in diameter) and long coils, the success rate of precision winding is very low. The survival rate of coils with acceptable drift is usually less than 20%, especially for ultra-high precision coils, where the survival rate is even lower. Therefore, given the inability to obtain coils with good symmetry, effectively utilizing the high resolution of the coils while avoiding their low-temperature drift characteristics is crucial for achieving effective research on high-performance gyroscopes, even when current technology cannot provide rapid breakthroughs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a high-precision fiber optic gyroscope temperature drift monitoring and error suppression system and method.

[0005] One of the objectives of this invention is achieved through the following technical solution:

[0006] A high-precision fiber optic gyroscope temperature drift monitoring and error suppression system includes a reference gyroscope, a monitoring gyroscope, a rotating heating cover, a synchronization carrier, a comparator, and a temperature compensation unit.

[0007] The reference gyroscope, which is a high-precision gyroscope with a large temperature drift coefficient, is used to handle noise output.

[0008] The monitoring gyroscope is a low-precision gyroscope with a small temperature drift coefficient, used to monitor the zero bias mean.

[0009] The monitoring gyroscope and the reference gyroscope are placed on the same carrier plane, and the sensitive axes of the two gyroscopes are arranged in parallel.

[0010] The synchronization carrier is used to install the reference gyroscope, the monitoring gyroscope, and the rotating heating cover;

[0011] The rotating heating cover is located outside the reference gyroscope and the monitoring gyroscope. The rotating heating cover is spherical and consists of two hemispheres, with a support point at the apex of each hemisphere. The two support points are rotatably supported on a fixed carrier by bearings, allowing the heating cover to rotate freely clockwise and counterclockwise around the normal to the plane of the carrier. The rotating heating cover is composed of spherical heating plates of equal width in the latitudinal direction, and each heating plate is equipped with a heating resistor.

[0012] The comparator is used to acquire the output signals of the reference gyroscope and the monitoring gyroscope, and to perform differential operations;

[0013] The temperature compensation unit is used to determine and address the conduction of the heating resistor based on the differential operation structure of the comparator and a neural network training model, and output the heating temperature and heating time to realize the rotation heating control of the rotating heating cover.

[0014] Furthermore, the ratio of the accuracy of the monitoring gyroscope to that of the reference gyroscope is not less than 5; and the ratio of the temperature sensitivity coefficient of the monitoring gyroscope to that of the reference gyroscope does not exceed 1 / 5.

[0015] The second objective of this invention is achieved through the following technical solution:

[0016] A method for high-precision fiber optic gyroscope temperature drift monitoring and error suppression system, based on the aforementioned high-precision fiber optic gyroscope temperature drift monitoring and error suppression system, includes the following steps:

[0017] Step 1: The outputs of the reference gyroscope and the monitoring gyroscope are collected in real time by a comparator, and the difference is calculated. When the ratio of the absolute value of the difference between the outputs of the two gyroscopes to the absolute value of the drift value of the output of the monitoring gyroscope is greater than the zero bias threshold set for heating start, it is determined that the temperature excitation caused the gyroscope to drift.

[0018] Step 2: If the gyroscope is confirmed to be drifting in Step 1, the rotating heating cover is controlled by the temperature compensation unit. The rotating heating cover rotates at a fixed speed with the rotation axis perpendicular to the carrier plane. The rotating heating cover uses zone heating, which circulates the heating elements near the gyroscope carrier plane. After the zone heating temperature reaches the set value, the rotating heating cover rotates periodically and continuously left and right with a rotation start-stop duty cycle of 1:1 until the temperature field is uniform.

[0019] Step 3: When the ratio of the absolute value of the difference between the outputs of the two gyroscopes to the absolute value of the output drift of the monitoring gyroscope does not exceed the set zero bias threshold, the outputs of the two gyroscopes are combined as the effective gyroscope output. The combination method is as follows: the average value of the monitoring gyroscope output is used as the zero bias average value, and the noise output of the reference gyroscope is used as the gyroscope noise.

[0020] Step 4: Output and record the gyroscope data obtained in Step 3.

[0021] Furthermore, in step 1, the expression for the zero bias threshold k is:

[0022] k = |E 参考 -E 监控 | / |E 监控 | ≥ 5;

[0023] Where E is the gyroscope output bias stability, E 误差 To reference the stability of the gyroscope and monitor the difference in output speed, E 监控 To monitor the stability of the gyroscope's output speed.

[0024] Furthermore, in step 2, the rotating heating shroud uses constant-temperature heating. The heating temperature and heating time are generated by the temperature compensation unit using a neural network training model. The inputs to the neural network training model are the initial ambient temperature T0 and the gyroscope's zero-bias stability error E. 误差 ;T out The output matrix is ​​composed of t, which represents the output heating temperature and heating time, respectively. IW and LW are the neural network weight factors, as shown in the following formula:

[0025]

[0026] The advantages and positive effects of this invention are as follows:

[0027] This invention proposes a complementary output method using two gyroscopes. One gyroscope serves as the primary output gyroscope—the reference gyroscope—responsible for noise output, while the other serves as an auxiliary gyroscope—the monitoring gyroscope—responsible for monitoring the zero-bias mean. The complementary outputs of the two gyroscopes correct for temperature drift and current noise changes. The gyroscope drift caused by temperature excitation is promptly detected based on the output difference between the two gyroscopes, and the movement and heating of the rotating heating shroud are controlled through a temperature compensation unit. This method effectively achieves high-precision temperature drift monitoring and error suppression for fiber optic gyroscopes, offering good controllability. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the gyroscope drift monitoring system of the present invention;

[0029] Figure 2 This is a flowchart of the gyroscope drift monitoring and error suppression process of the present invention. Detailed Implementation

[0030] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.

[0031] The design concept of this invention is as follows: High-temperature performance gyroscopes are not uncommon in the medium-precision gyroscope market. Practical experience shows that the temperature performance of medium-precision gyroscope rings is generally superior to that of high-precision rings. This is mainly because the medium-precision fiber optic gyroscope ring technology is mature and there are numerous samples available. More importantly, medium-precision rings have smaller ring sizes, limited layers and turns, and lower symmetry weighting factors compared to high-precision rings. Therefore, high-temperature rings can be selected from medium-precision gyroscopes. However, the core reason why medium-precision gyroscope rings cannot achieve high precision is that the insufficient ring size leads to insufficient sensitivity; this fundamental hurdle of insufficient sensitivity cannot be overcome. This hurdle is precisely what high-precision, large-size rings inherently possess. Therefore, even with poor temperature performance, high-precision rings can still effectively handle short-term noise, making it easy to obtain two gyroscopes with different performance characteristics.

[0032] Based on the superior temperature performance of medium-precision gyroscopes compared to high-precision gyroscopes and the higher sensitivity of high-precision gyroscopes compared to medium-precision gyroscopes, this invention proposes a complementary output monitoring system using two gyroscopes. One gyroscope serves as the primary output gyroscope—the reference gyroscope—mainly responsible for noise output, while the other serves as the auxiliary gyroscope—the monitoring gyroscope—mainly responsible for monitoring the zero-bias mean. The two gyroscopes complement each other to correct temperature drift and current noise changes. Gyroscope monitoring technology uses a low-cost, small gyroscope as a monitor, with temperature changes corresponding to environmental changes. The reference gyroscope may have poorer temperature performance but higher resolution, resulting in higher cost. The monitoring gyroscope itself has excellent temperature performance, is insensitive to temperature, and has lower cost. To better utilize the mean-averaging characteristic, both gyroscopes are placed within a temperature-controlled rotating heating enclosure with good temperature performance. The monitoring gyroscope is in vibration isolation mode, and both gyroscopes are on the same synchronous carrier. The monitoring gyroscope extracts lower-frequency signals, such as slow rotation speed changes and medium- to long-term magnetic field changes. The reference gyroscope can effectively extract high-frequency disturbance information in the environment, such as vibration noise and magnetic field excitation.

[0033] To effectively monitor gyroscope error changes, a compensation amount is obtained by multiplying the gyroscope output contrast value by a compensation coefficient matrix. This compensation amount is then multiplied by the ambient input temperature Tin and fed back to the rotating heating shroud. The rotating heating shroud adjusts the heating element temperature and rotation speed according to the feedback network to quickly counteract temperature shocks. The compensation coefficient matrix can employ a neural network system or a linear fixed-length coefficient matrix. The aforementioned compensation coefficient matrix was obtained through multiple experimental training and compensation processes.

[0034] The specific positional relationship of the monitoring system is as follows: the monitoring gyroscope and the reference gyroscope are placed on the same carrier plane, and the sensitive axes of the two gyroscopes are parallel. The rotating heating cover is spherical and consists of two hemispheres, with a support point at the apex of each hemisphere. It is rotatably supported on the fixed carrier by ball bearings, allowing the heating cover to rotate freely clockwise and counterclockwise around the normal of the carrier plane.

[0035] Before determining that a large temperature fluctuation is causing gyroscope drift, it is necessary to effectively identify whether the change in the zero bias of the monitored gyroscope is due to temperature excitation or the motion of the carrier. The basic principle is: if the carrier is moving, both gyroscopes can sense it, and in this case, the difference between the output speeds of the two gyroscopes will result in no additional drift.

[0036] After ruling out the influence of carrier motion on the gyroscope's zero-bias change, a zero-bias threshold criterion needs to be determined. Based on this threshold, the heating shroud is activated to achieve uniform temperature distribution. Generally, the monitoring gyroscope exhibits a small temperature drift, while the reference gyroscope has a temperature drift sensitivity coefficient inversely proportional to its accuracy. Assume the monitoring gyroscope's accuracy σ... 监控 =0.001゜ / h, reference gyroscope accuracy is σ 参考 =0.0002° / h, the accuracy ratio of the two gyroscopes is 5. Generally, the sensitivity coefficients and accuracy ratios of the reference gyroscope and the monitoring gyroscope to temperature are negatively correlated. To illustrate, suppose a change in ambient temperature causes a zero bias change of 0.0003° / h for the reference gyroscope, but the impact of this temperature fluctuation on the monitoring gyroscope does not exceed 0.0003°.

[0037] / h / 5=0.00006゜ / h. In this case, after deducting the influence of carrier motion, the zero bias change of the two gyroscopes combined does not exceed 0.00036゜ / h, which still achieves a relatively high accuracy. However, when the external temperature change causes the reference gyroscope's accuracy drift to reach 0.001゜ / h, the monitoring gyroscope's temperature drift reaches 0.001゜ / h / 5=0.0002゜ / h. At this point, the worst-case accuracy of the two gyroscopes combined reaches 0.0012゜ / h, which can no longer meet the requirements for improved accuracy. Therefore, small temperature interference will not affect the noise of the monitoring gyroscope in the short term, but when there is a relatively high-frequency temperature excitation, the monitoring gyroscope will be excited to a large temperature drift, which will seriously affect the gyroscope's accuracy. In this case, it is necessary to homogenize the ambient temperature to reduce the temperature drift error of the monitoring gyroscope. When the external temperature causes drift, the reference gyroscope will be more sensitive than the monitoring gyroscope. The difference between the outputs of the two gyroscopes will produce an output deviation E. 误差 =E 参考 -E 监控 The criterion for ensuring even heating upon startup of the heating shroud can be preset as: k = E 误差 / E 监控In other words, when the above-mentioned deviation threshold is exceeded, this temperature drift needs to be eliminated. The method of elimination is to adopt a rapid rotational homogenization method to eliminate the non-uniformity of the temperature field gradient. Based on the invention of gyroscope monitoring, this invention proposes to collect and monitor the zero-bias change of the monitoring gyroscope and compare it with the zero-bias change of a reference gyroscope. By comparing the zero-bias change with the threshold value, the rotation of the partitioned rotating heating cover is controlled to achieve homogenization, thereby achieving a drift suppression method to counteract external temperature changes.

[0038] Based on the above, the high-precision fiber optic gyroscope temperature drift monitoring and error suppression method of the present invention includes the following five steps:

[0039] (1): Fabrication of a rotating frame and a rotating heating cover. The two hemispherical heating covers are fixed to the isolation carrier by a frame connected by upper and lower bearings, forming a rotating heating device;

[0040] (2): Select two gyroscopes that can be combined. One is a reference gyroscope with high precision but a large temperature drift coefficient, and the other is a monitoring gyroscope with low precision but a small temperature drift coefficient. Place them on the same carrier plane inside the rotating heating cover. The precision ratio between the low precision gyroscope and the high precision gyroscope should not be less than 5, and the temperature sensitivity coefficient between the low precision gyroscope and the high precision gyroscope should not exceed 0.2.

[0041] (3): Rotational heating control: Heating control is initiated based on the fact that the ratio of the stability of the absolute value difference between the outputs of the two gyroscopes to the stability of the absolute value of the output of the monitored gyroscope is greater than the heating start criterion. The rotating heating cover rotates at a fixed speed, with the rotation axis perpendicular to the plane of the carrier, at a speed of 6° / s. The rotating heating cover is composed of spherical heating plates of equal width in the latitudinal direction, with a plate width w. Each heating plate is equipped with a heating resistor, and the conduction of the heating resistor is determined and addressed by the temperature compensation unit. The heating temperature and heating time are calculated and determined by the temperature compensation unit.

[0042] (4): Perform gyroscope data acquisition and processing: The ratio of the stability of the absolute value of the difference between the outputs of the two gyroscopes to the stability of the absolute value of the output of the monitoring gyroscope does not exceed the temperature heating criterion, and the outputs of the two gyroscopes are combined as the effective gyroscope output; the combination method is to use the average value of the monitoring gyroscope output as the zero bias average value and the reference gyroscope noise output as the gyroscope noise.

[0043] (5): Output and record the gyroscope data.

[0044] The specific implementation method of the above-mentioned rotary heating control:

[0045] Assuming a significant temperature change occurs in the two gyroscopes within a short period, the comparator will capture a large difference. The gyroscopes can mitigate the effect of temperature on their performance through rotation and localized heating. Specifically, the rotational angular rate and heating measures are as follows:

[0046] A typical angular velocity is 6° / s. Assuming a rotation time of t seconds, followed by a stop of t seconds, this cycle is repeated until the temperature field is uniform. The rotating heating hood employs a zoned heating method. The hood rotates along a fixed axis, and heating elements are evenly distributed on the hood in a spherical pattern. The heating element electrodes are powered by contact brushes. The specific heating temperature can be controlled by constant or variable temperature, where the variable temperature is determined by a compensation coefficient matrix. For simplicity, this invention preferably uses constant temperature control (heating element temperature is T). out (℃), the typical heating curve is shown in the figure. After the zone heating temperature reaches the set value, the rotating heating cover rotates periodically and continuously left and right. The rotation start-stop duty cycle is 1:1, which can be, but is not limited to, a typical event where start and stop each occupy t seconds.

[0047] A differential filter is applied to the monitoring gyroscope, meaning the gyroscope output is differentially analyzed to obtain gyroscope noise. A smoothing filter is applied to the reference gyroscope, resulting in the average output gyroscope value. The zero-bias value of the monitoring gyroscope is amplified, and the resulting digital value is added to the monitoring gyroscope noise to obtain the synthesized gyroscope digital value, which serves as the final output of the synthesized gyroscope. The difference in drift between the two gyroscopes is extracted as a feedback value and sent to the temperature compensation unit. A neural network unit calculates the heating temperature and the required heating time. The heating element is rotated to heat the area to be heated (heating plate) to the specified temperature. The heating area is rotated cyclically, meaning the heating plate near the gyroscope carrier plane is cyclically heated until the temperature field is uniform. This achieves temperature field balance and compensates for gyroscope temperature drift, thereby reducing the gyroscope's zero-bias mean error.

[0048] The implementation method of the above temperature compensation unit:

[0049] The matrix is ​​generated by training the model using a neural network, where T out The output matrix is ​​composed of the initial temperature T0 and the heating time, respectively. IW and LW are the neural network weight factors, with 15 neurons trained on each. The inputs are the initial temperature T0 and the gyroscope error E. 误差 The input matrix is ​​a 1*2 matrix consisting of the output difference between the two gyroscopes. The matrix feedback network is represented by the weight matrix IW*LW.

[0050]

[0051] An example implementation of the weight matrix for 15 neurons is shown below:

[0052]

[0053] Although embodiments and drawings of the present invention have been disclosed for illustrative purposes, those skilled in the art will understand that various substitutions, variations and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A high-precision fiber optic gyroscope temperature drift monitoring and error suppression system, characterized in that: Includes a reference gyroscope, a monitoring gyroscope, a rotating heating cover, a synchronization carrier, a comparator, and a temperature compensation unit; The reference gyroscope, which is a high-precision gyroscope with a large temperature drift coefficient, is used to handle noise output. The monitoring gyroscope is a low-precision gyroscope with a small temperature drift coefficient, used to monitor the zero bias mean. The monitoring gyroscope and the reference gyroscope are placed on the same carrier plane, and the sensitive axes of the two gyroscopes are arranged in parallel. The synchronization carrier is used to install the reference gyroscope, the monitoring gyroscope, and the rotating heating cover; The rotating heating cover is located outside the reference gyroscope and the monitoring gyroscope. The rotating heating cover is spherical and consists of two hemispheres, with a support point at the apex of each hemisphere. The two support points are rotatably supported on a fixed carrier by bearings, allowing the heating cover to rotate freely clockwise and counterclockwise around the normal to the plane of the carrier. The rotating heating cover is composed of spherical heating plates of equal width in the latitudinal direction, and each heating plate is equipped with a heating resistor. The comparator is used to acquire the output signals of the reference gyroscope and the monitoring gyroscope, and to perform differential operations; The temperature compensation unit is used to determine and address the conduction of the heating resistor based on the differential operation structure of the comparator and a neural network training model, and output the heating temperature and heating time to realize the rotation heating control of the rotating heating cover.

2. The high-precision fiber optic gyroscope temperature drift monitoring and error suppression system according to claim 1, characterized in that: The ratio of the accuracy of the monitoring gyroscope to that of the reference gyroscope is not less than 5; the ratio of the temperature sensitivity coefficient of the monitoring gyroscope to that of the reference gyroscope does not exceed 1 / 5.

3. A method for high-precision fiber optic gyroscope temperature drift monitoring and error suppression system, based on the high-precision fiber optic gyroscope temperature drift monitoring and error suppression system of claim 1 or 2, comprising the following steps: Step 1: The outputs of the reference gyroscope and the monitoring gyroscope are collected in real time by a comparator, and the difference is calculated. When the ratio of the absolute value of the difference between the outputs of the two gyroscopes to the absolute value of the drift value of the output of the monitoring gyroscope is greater than the zero bias threshold set for heating start, it is determined that the temperature excitation caused the gyroscope to drift. Step 2: If the gyroscope is confirmed to be drifting in Step 1, the rotating heating cover is controlled by the temperature compensation unit. The rotating heating cover rotates at a fixed speed with the rotation axis perpendicular to the carrier plane. The rotating heating cover uses zone heating, which circulates the heating elements near the gyroscope carrier plane. After the zone heating temperature reaches the set value, the rotating heating cover rotates periodically and continuously left and right with a rotation start-stop duty cycle of 1:1 until the temperature field is uniform. Step 3: When the ratio of the absolute value of the difference between the outputs of the two gyroscopes to the absolute value of the output drift of the monitoring gyroscope does not exceed the set zero bias threshold, the outputs of the two gyroscopes are combined as the effective gyroscope output. The combination method is as follows: the average value of the monitoring gyroscope output is used as the zero bias average value, and the noise output of the reference gyroscope is used as the gyroscope noise. Step 4: Output and record the gyroscope data obtained in Step 3.

4. The method for high-precision fiber optic gyroscope temperature drift monitoring and error suppression system according to claim 3, characterized in that: In step 1, the expression for the zero bias threshold k is: k=|E 参考 -AND 监控 | / |E 监控 | ≥ 5; Where E is the gyroscope output bias stability, E 误差 To reference the stability of the gyroscope and monitor the difference in output speed, E 监控 To monitor the stability of the gyroscope's output speed.

5. The method for high-precision fiber optic gyroscope temperature drift monitoring and error suppression system according to claim 3, characterized in that: In step 2, the rotating heating hood uses constant-temperature heating. The heating temperature and heating time are generated by the temperature compensation unit using a neural network training model. The input to the neural network training model is the initial ambient temperature T0 and the gyroscope error E. 误差 ;T out The output matrix is ​​composed of t, which represents the output heating temperature and heating time, respectively. IW and LW are the neural network weight factors, as shown in the following formula:

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