Atomic magnetometer external field low magnetic heading error test method and system

Abstract

The application provides a kind of atomic magnetometer external field low magnetic heading error test method and system, to be measured magnetometer and reference magnetometer are installed in calibration turntable, two magnetometers are differentiated to eliminate environmental magnetic field fluctuation, the rotation direction of three-axis of turntable control system is controlled through universal transmission rod, and the necessary rotation action required for carrying out heading error test, the heading error test is realized through fixed process, the sky screen is used to provide the necessary rain protection ability for test system, and the environmental adaptability is improved.Each component in the method is strictly designed without magnetism, the residual magnetism of each component needs to be less than 1nT level, various environmental disturbances in the external test environment are avoided, and the environmental applicability and robustness are improved.The technical scheme of the application is used to solve the technical problems of the existing technology, such as the changeable geomagnetic field direction in the heading error calibration process of atomic magnetometer, the large magnetic field environment fluctuation and the low efficiency of manual calibration.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of quantum sensing, and in particular to a method and system for testing heading error of an atomic magnetometer in an external field. BACKGROUND

[0002] At present, commercial magnetometers have increasingly high requirements for sensitivity and volume. As a new generation of magnetometer, the atomic magnetometer has a sensitivity that exceeds that of traditional magnetometers. The sensitivity of each commercial scalar atomic magnetometer suitable for the geomagnetic field is at the level of 1 pT / Hz1 / 2, which provides new possibilities for geomagnetic field measurement, geomagnetic navigation, and resource exploration. However, due to the limitations of existing material production and processing manufacturing processes, the atomic magnetometer inevitably has a remanence of the order of nT, which further projects to generate an atomic magnetometer heading error. Since the atomic magnetometer inevitably changes its attitude during actual use, to avoid limiting the magnetic field resolution of the atomic magnetometer during magnetic field measurement, it is necessary and challenging to calibrate the heading error of the atomic magnetometer without limiting its high sensitivity. Due to different application scenarios of the atomic magnetometer, the atomic magnetometer needs to be calibrated for heading error in the actual use environment. In different use environments, the geomagnetic field inclination is different, and how to construct a non-magnetized tool to assist the atomic magnetometer to adapt to different magnetic inclinations is one of the necessary works of a universal test device. It is worth noting that the theory can simulate the external field environment for heading error calibration in the laboratory state, but the magnetic field environment in the laboratory currently has a magnetic field gradient effect, which leads to a significant difference between the test results in the laboratory state and the external field. Therefore, it is necessary to choose an external field with a more uniform magnetic field to reduce the error. In addition, due to the differences between the real environment and the shielding environment in the laboratory, there are environmental magnetic field disturbances such as cars, power cables, ships, and test equipment themselves. The heading error calibration needs to overcome various environmental disturbances to improve the accuracy. Due to the high sensitivity of the atomic magnetometer, there is currently a lack of automatic test procedures for the atomic magnetometer. The traditional laboratory stage atomic magnetometer heading error test method is in the manual testing stage, which limits the batch production and application of the atomic magnetometer. SUMMARY

[0003] The present application provides a method and system for testing the heading error of an atomic magnetometer in an external field with low magnetism, which can solve the technical problems of the heading error calibration process of the atomic magnetometer in the prior art, such as the variability of the geomagnetic field direction, the large fluctuations of the magnetic field environment, and the low efficiency of manual calibration.

[0004] According to one aspect of the present invention, a method for testing the heading error of an atomic magnetometer in an external field with low magnetic field is provided. The method includes: setting up a canopy, a calibration turntable, a universal joint, and a turntable control system. The turntable control system includes a control computer and a three-channel servo motor. The calibration turntable includes a reference magnetometer fixture, a magnetometer under test fixture, a three-axis turntable, a level, and a three-axis magnetoresistive field. The canopy provides shielding for the heading error test, ensuring test continuity after power-on. The magnetometer under test is fixed to the three-axis turntable using the magnetometer under test fixture, and a reference magnetometer is fixed outside the three-axis turntable using the reference magnetometer fixture, providing a reference for the magnetometer under test during the calibration test. To test the magnetic field, the magnetic field signals of the magnetometer under test and the reference magnetometer are different to eliminate the influence of common magnetic field interference sources in the external field. When installing the calibration turntable, the level installed on the calibration turntable should be used to stably install the three-axis turntable on the ground to provide a stable environment for magnetometer debugging. After installing the two magnetometers onto the three-axis turntable, the direction of the geomagnetic field is identified by the three-axis magnetoresistive method. The three-axis turntable is rotated to align the sensitive axis of the atomic magnetometer with the direction of the geomagnetic field to avoid the influence of the geomagnetic field tilt angle on the test results. The three-axis turntable is connected to the three-channel servo motor using a universal transmission rod to transmit the motion of the three-channel servo motor to the three-axis turntable. The automated test process in the control computer is used to complete the automatic test of the low magnetic heading error of the atomic magnetometer in the external field.

[0005] Furthermore, the automated testing process within the control computer to automatically test the low-magnetic heading error of the atomic magnetometer specifically includes: defining the atomic magnetometer's sensitivity direction as the y-direction, the roll-sensitive direction as the x-direction, and the heading-sensitive direction as the z-direction; dividing the entire range of the atomic magnetometer's magnetic field in the z-direction into 11 positions; using a servo motor with a universal joint, rotating the magnetometer ±60° at each position while simultaneously recording the differential magnetic field of the two magnetometers; taking the position with the smallest differential magnetic field data offset among the 11 positions; using the two adjacent positions as upper and lower limits, taking another 21 positions evenly; again, rotating the magnetometer ±60° at each position while simultaneously recording the differential magnetic field data; taking the position with the smallest differential magnetic field offset as the z-direction magnetic field compensation value; after the magnetometer's heading position is zeroed, dividing the entire range of the atomic magnetometer's magnetic field in the y-direction into 11 positions; using a servo motor with a universal joint, rotating the magnetometer ±60° at each position while simultaneously recording the differential magnetic field of the two magnetometers; taking the smallest differential magnetic field offset among the 11 positions as the z-direction magnetic field compensation value; The position with the smallest deviation of the differential magnetic field data is used as the upper and lower limits, and 21 positions are evenly selected again. Each position is then rotated ±60° in the heading motion, and the differential magnetic field data is recorded simultaneously. The position with the smallest deviation of the differential magnetic field is taken as the magnetic field compensation value in the y-direction. After the magnetometer's heading position is zeroed, the entire range of the atomic magnetometer's magnetic field in the x-direction is evenly divided into 11 positions. A servo motor, using a universal joint, rotates ±60° at each position, simultaneously recording the differential magnetic field of the two magnetometers. The value of 1 is then taken. The position with the smallest differential magnetic field data offset change is identified at position 1. Using the two adjacent positions as upper and lower limits, 21 positions are uniformly selected again. Each position is then rotated ±60°, and the differential magnetic field data is recorded synchronously. The position with the smallest differential magnetic field offset change is taken as the magnetic field compensation value in the x-direction. The roll direction is set to zero, and the servo motor controls the three-axis turntable to rotate the sensitive axis of the atomic magnetometer 180°. The above steps are repeated to perform the test again, and two sets of magnetometer compensation values ​​are output to complete the atomic magnetometer's external field low magnetic heading error test.

[0006] Furthermore, the canopy's frame uses fiberglass or carbon fiber, the metal fixing structure uses titanium, and the ground anchors use plastic.

[0007] Furthermore, the three-axis rotary table is manufactured using polyimide plastic, and the fixing structure of the calibration rotary table is fixed with plastic or nylon screws.

[0008] Furthermore, the universal joint drive rod is custom-made using materials such as polytetrafluoroethylene (PTFE).

[0009] Furthermore, the universal joint increases the distance between the calibration turntable and the three-axis servo motor to over 2 meters.

[0010] Furthermore, the distance between the control computer and the calibration turntable is greater than or equal to 5m.

[0011] According to another aspect of the present invention, an atomic magnetometer external field low magnetic heading error testing system is provided, which uses the atomic magnetometer external field low magnetic heading error testing method described above to perform heading error testing.

[0012] Furthermore, the atomic magnetometer's external low-magnetic heading error testing system includes a canopy, a calibration turntable, a universal joint, and a turntable control system. The turntable control system includes a control computer and a three-channel servo motor. The calibration turntable includes a reference magnetometer fixture, a magnetometer under test fixture, a three-axis turntable, a level, and a three-axis magnetoresistive sensor. The canopy provides shielding for the heading error test, ensuring test continuity after power-on. The magnetometer under test fixture secures the magnetometer to be tested onto the three-axis turntable, and the reference magnetometer fixture secures the reference magnetometer to the outside of the three-axis turntable, providing protection for the magnetometer under test during calibration. The reference magnetic field and the magnetic field signals of the magnetometer under test and the reference magnetometer are out of phase to eliminate the influence of common magnetic field interference sources in the external field; the level is used to stably install the three-axis turntable on the ground, providing a stable environment for magnetometer debugging; the three-axis magnetoresistive field is used to identify the direction of the geomagnetic field, and rotating the three-axis turntable aligns the sensitive axis of the atomic magnetometer with the direction of the geomagnetic field, avoiding the influence of the geomagnetic field tilt angle on the test results; the universal joint is used to connect the three-axis rotation mechanism of the three-axis turntable to the three-channel servo motor, transmitting the motion of the three-channel servo motor to the three-axis turntable, and the control computer is used to complete the automatic testing of the low magnetic heading error of the atomic magnetometer in the external field.

[0013] This invention provides a method for testing the heading error of an atomic magnetometer in an external field under low magnetic field conditions. The method includes a canopy, a calibration turntable, a universal joint, and a turntable control system. The magnetometer under test and a reference magnetometer are installed within the calibration turntable. The two magnetometers are differentially coupled to eliminate environmental magnetic field fluctuations, avoiding various environmental interferences in the external testing environment and improving environmental applicability and robustness. The turntable control system controls the rotation direction of the three axes of the turntable via the universal joint, as well as the necessary rotational movements required for heading error testing. The heading error test is performed through a fixed process. The canopy provides necessary rain protection for the testing system, improving environmental adaptability. Since the geomagnetic inclination varies in different operating environments, the three-axis turntable, combined with three-axis magnetoresistive coupling, effectively solves the specific environmental applicability problem in the heading error calibration process. The automatic process control of the three-axis rotation using servo motors realizes the automated calibration process of the atomic magnetometer's heading error, improving testing efficiency in the next stage of mass production and application of the atomic magnetometer. The method for testing the heading error of an atomic magnetometer in a low-magnetic field provided by this invention can solve the problems of variable geomagnetic field direction, large magnetic field environment fluctuation, and low efficiency of manual calibration in the heading error calibration process of atomic magnetometers in the prior art. The system design avoids the residual magnetism interference of the test equipment itself, maximizes the high sensitivity characteristics of the atomic magnetometer, and provides an effective automated calibration method for atomic magnetometers to adapt to different field magnetic field environments and improve the environmental adaptability of heading error calibration. Attached Figure Description

[0014] The accompanying drawings, which form part of this specification, are provided to further illustrate embodiments of the invention and, together with the textual description, explain the principles of the invention. It is obvious that the drawings described below are merely some embodiments of the invention, and those skilled in the art can obtain other drawings based on these drawings without any creative effort.

[0015] Figure 1 A schematic diagram of the automated process for testing the low magnetic heading error of an atomic magnetometer in the external field according to a specific embodiment of the present invention is shown.

[0016] Figure 2 A schematic diagram of the composition of an atomic magnetometer external field low magnetic heading error testing system provided according to a specific embodiment of the present invention is shown. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0019] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0020] like Figure 1As shown, according to a method for testing the heading error of an atomic magnetometer in an external field with low magnetic field strength, the method includes: setting up a canopy, a calibration turntable, a universal joint, and a turntable control system. The turntable control system includes a control computer and a three-channel servo motor. The calibration turntable includes a reference magnetometer fixture, a magnetometer under test fixture, a three-axis turntable, a level, and a three-axis magnetoresistive field. The canopy provides shielding for the heading error test, ensuring the continuity of the test after power-on. The magnetometer under test is fixed to the three-axis turntable using the magnetometer under test fixture, and the reference magnetometer is fixed outside the three-axis turntable using the reference magnetometer fixture, providing a reference magnetic field for the magnetometer under test during the calibration test. The magnetic field signals of the magnetometer under test and the reference magnetometer are out of phase to eliminate the influence of common magnetic field interference sources in the external field. When installing the calibration turntable, the level installed on the calibration turntable should be used to stably install the three-axis turntable on the ground to provide a stable environment for magnetometer debugging. After installing the two magnetometers onto the three-axis turntable, the direction of the geomagnetic field is identified by the three-axis magnetoresistive method. The three-axis turntable is rotated to align the sensitive axis of the atomic magnetometer with the direction of the geomagnetic field to avoid the influence of the geomagnetic field tilt angle on the test results. The three-axis turntable is connected to the three-channel servo motor using a universal joint to transmit the motion of the three-channel servo motor to the three-axis turntable. The automated test process in the control computer is used to complete the automatic test of the low magnetic heading error of the atomic magnetometer in the external field.

[0021] This configuration provides a method for testing the heading error of an atomic magnetometer in an outdoor low-magnetic environment. The method includes a canopy, a calibration turntable, a universal joint, and a turntable control system. The magnetometer under test and a reference magnetometer are installed within the calibration turntable. The two magnetometers are differentially coupled to eliminate environmental magnetic field fluctuations, avoiding various environmental interferences in the outdoor testing environment and improving environmental applicability and robustness. The turntable control system controls the rotation direction of the three axes of the turntable via the universal joint, as well as the necessary rotational movements required for heading error testing. The heading error test is performed through a fixed process. The canopy provides necessary rain protection for the testing system, enhancing environmental adaptability. Since the geomagnetic inclination varies in different operating environments, the three-axis turntable, combined with three-axis magnetoresistive coupling, effectively solves the specific environmental applicability problem in the heading error calibration process. Combined with servo motors for automatic process control of the three-axis rotation, the heading error calibration process of the atomic magnetometer is automated, improving testing efficiency in the next stage of mass production and application of the atomic magnetometer. The method for testing the heading error of an atomic magnetometer in a low-magnetic field provided by this invention can solve the problems of variable geomagnetic field direction, large magnetic field environment fluctuation, and low efficiency of manual calibration in the heading error calibration process of atomic magnetometers in the prior art. The system design avoids the residual magnetism interference of the test equipment itself, maximizes the high sensitivity characteristics of the atomic magnetometer, and provides an effective automated calibration method for atomic magnetometers to adapt to different field magnetic field environments and improve the environmental adaptability of heading error calibration.

[0022] Furthermore, in this invention, the automated testing process within the control computer to automatically test the low-magnetic heading error of the atomic magnetometer specifically includes: defining the atomic magnetometer's sensitivity direction as the y-direction, the direction sensitive to roll motion as the x-direction, and the direction sensitive to heading motion as the z-direction; dividing the entire range of the magnetic field in the z-direction of the atomic magnetometer into 11 positions; using a servo motor with a universal joint, rotating the magnetometer ±60° at each position, while simultaneously recording the differential magnetic field of the two magnetometers; taking the position with the smallest differential magnetic field data offset change among the 11 positions; using the two adjacent positions of this smallest position as upper and lower limits, then uniformly selecting 21 positions again; again, rotating the magnetometer ±60° at each position, simultaneously recording the differential magnetic field data; taking the position with the smallest differential magnetic field offset change as the magnetic field compensation value in the z-direction; after the magnetometer's heading position is zeroed, dividing the entire range of the magnetic field in the y-direction of the atomic magnetometer into 11 positions; using a servo motor with a universal joint, rotating the magnetometer ±60° at each position, while simultaneously recording the differential magnetic field of the two magnetometers; taking the 11 positions... The position with the minimum bias change in the differential magnetic field data is selected. Using the two adjacent positions as upper and lower limits, 21 positions are uniformly selected again. Each position is then rotated ±60° in the heading motion, and the differential magnetic field data is recorded simultaneously. The position with the minimum bias change in the differential magnetic field is taken as the magnetic field compensation value in the y-direction. After the magnetometer's heading position is zeroed, the entire magnetic field range in the x-direction of the atomic magnetometer is divided into 11 positions. A servo motor, using a universal joint, rotates ±60° at each position, simultaneously recording the differential magnetic field of the two magnetometers. The position with the smallest differential magnetic field data offset change in position 11 is used as the upper and lower limits of the two adjacent positions. Then, 21 positions are uniformly selected again, and each position is rotated ±60°. The differential magnetic field data is recorded synchronously, and the position with the smallest differential magnetic field offset change is taken as the magnetic field compensation value in the x-direction. The roll direction is set to zero, and the servo motor controls the three-axis turntable to rotate the sensitive axis of the atomic magnetometer 180°. The above steps are repeated to perform the test again, and two sets of magnetometer compensation values ​​are output to complete the test of the atomic magnetometer's external field low magnetic heading error.

[0023] Furthermore, in this invention, each part of the testing method requires necessary demagnetization design. The canopy frame uses a fiberglass or carbon fiber frame, the metal fixing structure of the canopy uses titanium metal, and the ground stakes of the canopy use plastic. The three-axis turntable is manufactured using polyimide plastic, and the fixing structure of the calibration turntable is fixed using plastic or nylon screws. The universal drive rod is custom-made using polytetrafluoroethylene (PTFE) and other materials.

[0024] Furthermore, in this invention, since the servo motor itself cannot completely eliminate magnetism, the universal joint increases the distance between the calibration turntable and the three-axis servo motor to over 2 meters. A custom-made permalloy alloy shell is required outside the servo motor to shield its own magnetic field. This permalloy alloy shell must undergo high-current demagnetization treatment before use. The distance between the control computer and the calibration turntable is greater than or equal to 5 meters.

[0025] According to another aspect of the invention, such as Figure 2 As shown, an atomic magnetometer external field low magnetic heading error testing system is provided. This atomic magnetometer external field low magnetic heading error testing system uses the atomic magnetometer external field low magnetic heading error testing method described above to test heading error.

[0026] Furthermore, in this invention, the atomic magnetometer external field low magnetic heading error testing system includes a canopy, a calibration turntable, a universal joint, and a turntable control system. The turntable control system includes a control computer and a three-channel servo motor. The calibration turntable includes a reference magnetometer fixture, a magnetometer under test fixture, a three-axis turntable, a level, and a three-axis magnetoresistive field. The canopy provides shielding for the heading error test, ensuring test continuity after power-on. The magnetometer under test fixture is used to fix the magnetometer under test onto the three-axis turntable, and the reference magnetometer fixture is used to fix the reference magnetometer outside the three-axis turntable, providing protection for the magnetometer under test during the calibration test. The system provides a reference magnetic field, and the magnetic field signals of the magnetometer under test and the reference magnetometer are out of phase to eliminate the influence of common magnetic field interference sources in the external field. The level is used to stably install the three-axis turntable on the ground, providing a stable environment for magnetometer calibration. The three-axis magnetoresistive system is used to identify the direction of the geomagnetic field. Rotating the three-axis turntable aligns the sensitive axis of the atomic magnetometer with the direction of the geomagnetic field, avoiding the influence of the geomagnetic field tilt angle on the test results. The universal joint is used to connect the three-axis rotation mechanism of the three-axis turntable to the three-channel servo motor, transmitting the motion of the three-channel servo motor to the three-axis turntable. The control computer is used to complete the automatic testing of the low magnetic heading error of the atomic magnetometer in the external field.

[0027] To gain a further understanding of the present invention, the following description is provided in conjunction with... Figure 1 and Figure 2 The present invention provides a detailed description of the method and system for testing the low magnetic heading error of an atomic magnetometer in the external field.

[0028] like Figure 1 and Figure 2As shown, this invention provides a method for testing the heading error of an atomic magnetometer in an external field under low magnetic field conditions. The method includes a canopy, a calibration turntable, a universal joint, and a turntable control system. The magnetometer under test and a reference magnetometer are installed inside the calibration turntable. The two magnetometers are differentially coupled to eliminate environmental magnetic field fluctuations. The turntable control system controls the rotation direction of the three axes of the turntable via the universal joint, as well as the necessary rotational movements required for the heading error test. The heading error test is performed through a fixed procedure. The canopy is used to provide necessary rain protection for the testing system and improve environmental adaptability. Currently, the sensitivity of mainstream scalar atomic magnetometers is close to 1 pT / Hz. 1 / 2 Compared to the calibration of heading errors for magnetic sensors in traditional aircraft, automobiles, ships, and AR augmentation applications, the requirements for residual magnetism are much more stringent. This method employs a rigorous non-magnetic design for each component, ensuring that the residual magnetism of each part is less than 1 nT. This invention addresses the problem that existing heading error calibration methods are unsuitable for the increasingly demanding research, design, and production requirements of high-sensitivity atomic magnetometers. It provides an effective automated calibration method to improve the environmental adaptability of atomic magnetometers to different external magnetic field environments, thus enhancing the heading error calibration's environmental adaptability.

[0029] This invention provides a method for testing the heading error of an atomic magnetometer in a low-magnetic field. It addresses the problems of variable geomagnetic field direction, large magnetic field fluctuations, and low efficiency of manual calibration in existing atomic magnetometer heading error calibration processes. The method also systematically avoids interference from the residual magnetism of the testing equipment itself, maximizing the high sensitivity of the atomic magnetometer. The method includes a demagnetized canopy, a calibration turntable, a universal joint, and a turntable control system, along with a necessary automated heading error calibration process. The magnetometer under test, a reference magnetometer, and a triaxial magnetoresistive and level instrument are installed within the calibration turntable. The turntable control system rotates the three axes of the calibration turntable via the universal joint, completing the heading error calibration of the atomic magnetometer through an automated testing process.

[0030] Furthermore, each part of the testing method requires necessary demagnetization design. The canopy providing sunlight and rain protection for the testing device differs from traditional canopies; its frame should be made of corrugated fiber or carbon fiber, and the necessary metal fixing structures are recommended to be made of titanium. After manufacturing, the canopy should be cleaned promptly to avoid ferromagnetic residue. The ground stakes used to fix the canopy should be made of plastic. The canopy provides necessary shelter for the heading error testing device in the rainy environment of southern regions, ensuring the continuity of testing after power-on. The main structure of the calibration turntable is manufactured using plastic materials such as polyimide, and necessary fixing structures should be secured with plastic or nylon screws. The universal joint is a common mechanism; the entire unit needs to be custom-made using polytetrafluoroethylene (PTFE) and other materials. It connects the three-axis rotation mechanism of the calibration turntable to the servo motor in the turntable control system, transmitting the servo motor's motion to the turntable. Since the servo motor itself cannot be completely demagnetized, the universal joint needs to increase the distance between the calibration turntable and the servo motor to more than 2 meters. A custom-made permalloy housing is required for the servo motor to shield its own magnetic field. The permalloy housing must undergo high-current demagnetization treatment before use. The control computer section of the turntable control system should be kept at least 5 meters away from the calibration turntable. All components must undergo necessary residual magnetism testing before the device is assembled, with residual magnetism levels below 1 nT to ensure the entire testing system is demagnetized.

[0031] Furthermore, the calibration turntable includes a reference magnetometer fixture, a magnetometer under test fixture, a three-axis turntable, a level, and a three-axis magnetoresistive array. The magnetometer under test fixture is used to securely mount the magnetometer under test to the three-axis turntable, while the reference magnetometer fixture is used to fix the reference magnetometer outside the three-axis turntable, providing a reference magnetic field for the magnetometer under test during calibration testing. The difference in magnetic field signals between the two magnetometers eliminates the influence of common field interference sources such as air chambers, ships, and power cables, providing good environmental adaptability for atomic magnetometer heading error testing. Since environmental fluctuations caused by various interference sources during field testing are typically above 100 pT, eliminating environmental errors will help improve the accuracy of atomic magnetometer heading error calibration by an order of 10 pT.

[0032] Furthermore, the calibration turntable must be installed following necessary procedures. During installation, the level installed on the calibration turntable must be used to stably mount the three-axis turntable on the ground, providing a stable environment for magnetometer calibration. After installing the two magnetometers onto the three-axis turntable, the direction of the geomagnetic field is identified using the three-axis magnetoresistive method. The turntable is then rotated to align the sensitive axis of the atomic magnetometer with the geomagnetic field direction, avoiding the influence of the geomagnetic field tilt angle on the test results. Due to the significant difference in geomagnetic tilt angle between northern and southern China, the combined use of the three-axis turntable and the three-axis magnetoresistive method helps this testing method to be applicable to various domestic field environments, increasing its adaptability to specific field conditions.

[0033] Furthermore, the control computer of the turntable control system includes necessary automated testing procedures, avoiding the currently common manual calibration. During testing, a common scalar magnetometer is used as an example. The sensitivity direction of the atomic magnetometer is defined as the y-direction, the direction sensitive to roll motion is defined as the x-direction, and the direction sensitive to yaw motion is defined as the z-direction. The magnetic compensation range for each direction is ±3nT. After segmented testing, the final accuracy meets 30pT, which is close to the peak-to-peak value of the short-time drift of the differential magnetic field in the external environment, thus meeting the requirements. The magnetic compensation is based on the fact that when the magnetometer has no yaw error, the residual magnetism in each direction will no longer affect the magnetometer output when the magnetometer rotates; otherwise, it will lead to distortion of the output magnetic field. The specific calibration process is as follows: Divide the magnetic field range of the atomic magnetometer in the z-direction into 10 segments. After testing, the result is position 11. The servo motor rotates the y-direction ±60° horizontally via the universal joint drive shaft, while simultaneously recording the differential magnetic field of the two magnetometers. The position with the smallest differential magnetic field data offset change in position 11 is selected. Using the two adjacent positions of this smallest position as upper and lower limits, position 21 is selected again. The y-direction is rotated ±60° at each position, and the differential magnetic field data is recorded synchronously. The position with the smallest differential magnetic field offset change is selected as the magnetic field compensation value in the z-direction. After the magnetometer's y-direction position is zeroed, the magnetic field in the y-direction is similarly divided into positions 11 and 21, with a y-direction rotation of ±60°. However, the position with the smallest peak-to-peak value of the differential magnetic field data is selected as the output value in the y-direction. After the magnetometer's y-direction position is zeroed, a roll motion is performed to rotate ±60°. Positions 10 and 21 are selected sequentially. The position with the lowest differential magnetic field data offset change is then used for judgment, and the magnetic field compensation value in the x-direction is output. Since the heading error of an atomic magnetometer is not the same when it is in the same direction or opposite to the Earth's magnetic field in actual application, after compensating for the residual magnetism in the x, y, and z directions, the atomic magnetometer is rotated 180° in the sensitive axis direction and tested again to improve the heading error test results.

[0034] In summary, this invention provides a method for testing the heading error of an atomic magnetometer under low magnetic field conditions. By designing each component to be unmagnetized, a sensitivity of 1 pT / Hz is achieved. 1 / 2 Low-interference, high-precision heading error testing of a horizontal atomic magnetometer. By using dual-head differential testing, various environmental interferences in the field testing environment are avoided, improving environmental applicability and robustness. Due to the different geomagnetic tilt angles in different operating environments, a three-axis turntable integrated with three-axis magnetoresistive technology effectively solves the specific environmental applicability problem in the heading error calibration process. Combined with servo motors for automatic process control of the three-axis rotation, the heading error calibration process of the atomic magnetometer is automated, improving testing efficiency in the next stage of mass production applications. It is worth noting that, unlike the heading error calibration methods of magnetic sensors in traditional fields such as aircraft, automobiles, and ships, the atomic magnetometer's 1pT / Hz... 1 / 2The high horizontal sensitivity means that traditional calibration methods and equipment (such as metal turntables and metal transmission mechanisms) are no longer applicable. Otherwise, magnetic noise and remanence would overwhelm the performance of the atomic magnetometer itself. Traditional magnetometer testing methods based on nT-level magnetic field resolution are no longer suitable. A complete redesign of the heading error calibration is necessary and essential. This technical solution is simple and easy to operate. Combining the high sensitivity of the atomic magnetometer, a complete heading error calibration system and method have been designed. This system can directly serve the manufacturing process of the atomic magnetometer, providing a foundation for its future large-scale production and application.

[0035] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0036] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0037] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for testing the heading error of an atomic magnetometer under low magnetic field conditions, characterized in that, The method for testing the low-magnetic heading error of the atomic magnetometer in the external field includes: The system includes a canopy, a calibration turntable, a universal transmission rod, and a turntable control system. The turntable control system includes a control computer and a three-channel servo motor. The calibration turntable includes a reference magnetometer fixture, a magnetometer fixture to be measured, a three-axis turntable, a level, and a three-axis magnetoresistive system. The canopy is used to provide shielding for the heading error test, ensuring the continuity of the test after power-on; The magnetometer under test is fixed on the three-axis turntable using the fixing component of the magnetometer under test, and the reference magnetometer is fixed outside the three-axis turntable using the fixing component of the reference magnetometer, so as to provide a reference magnetic field for the magnetometer under test during the calibration test. The magnetic field signals of the magnetometer under test and the reference magnetometer are different to eliminate the influence of common magnetic field interference sources in the external field on the magnetic field. When installing the calibration turntable, the level installed on the calibration turntable should be used to stably install the three-axis turntable on the ground to provide a stable environment for the magnetometer calibration. After installing the two magnetometers onto the three-axis turntable, the direction of the geomagnetic field is identified by the three-axis magnetoresistive method. The three-axis turntable is rotated to align the sensitive axis of the atomic magnetometer with the direction of the geomagnetic field to avoid the influence of the geomagnetic field tilt angle on the test results. The three-axis rotary table is connected to the three-channel servo motor using the universal transmission rod, and the motion of the three-channel servo motor is transmitted to the three-axis rotary table. The automated testing process within the control computer is used to automatically test the low magnetic heading error of the atomic magnetometer in the external field.

2. The method for testing the low-magnetic heading error of an atomic magnetometer in an external field according to claim 1, characterized in that, The automated testing process within the control computer for the low-magnetic heading error of the atomic magnetometer specifically includes: Define the direction of sensitivity of the atomic magnetometer as the y-direction, the direction of sensitivity to roll motion as the x-direction, and the direction of sensitivity to heading motion as the z-direction; The entire range of the magnetic field in the z-direction of the atomic magnetometer is divided into 11 positions. The servo motor rotates ±60° at each position using a universal drive shaft, while simultaneously recording the differential magnetic field of the two magnetometers. The position with the smallest change in the differential magnetic field data among the 11 positions is selected. The two positions adjacent to this smallest position are used as the upper and lower limits. Then, 21 positions are selected again, and the horn is rotated ±60° at each position again, while simultaneously recording the differential magnetic field data. The position with the smallest change in the differential magnetic field bias is taken as the magnetic field compensation value in the z-direction. After the magnetometer's heading position is zeroed, the entire range of the magnetic field in the y-direction of the atomic magnetometer is divided into 11 positions. The servo motor rotates ±60° at each position using the universal drive shaft, while simultaneously recording the differential magnetic field of the two magnetometers. The position with the smallest change in the differential magnetic field data among the 11 positions is selected. Using the two positions adjacent to this smallest position as the upper and lower limits, 21 positions are selected again. The heading rotation is performed ±60° at each position again, and the differential magnetic field data is recorded synchronously. The position with the smallest change in the differential magnetic field bias is taken as the magnetic field compensation value in the y-direction. After the magnetometer's heading position is zeroed, the entire range of the magnetic field in the x-direction of the atomic magnetometer is divided into 11 positions. The servo motor rotates ±60° at each position using the universal drive shaft, while simultaneously recording the differential magnetic field of the two magnetometers. The position with the smallest change in the differential magnetic field data among the 11 positions is selected. Using the two positions adjacent to this smallest position as the upper and lower limits, 21 positions are selected again, and the rotation is performed ±60° at each position again, while simultaneously recording the differential magnetic field data. The position with the smallest change in the differential magnetic field bias is taken as the magnetic field compensation value in the x-direction. Set the roll direction to zero, and control the three-axis turntable to rotate the atomic magnetometer's sensitive axis by 180° using the servo motor. Repeat the above steps to perform the test again, output two sets of magnetometer compensation values, and complete the atomic magnetometer's external field low magnetic heading error test.

3. The method for testing the low-magnetic heading error of an atomic magnetometer in an external field according to claim 2, characterized in that, The canopy's frame uses a fiberglass or carbon fiber frame, the canopy's metal fixing structure uses titanium metal, and the canopy's ground nails use plastic material.

4. The method for testing the low-magnetic heading error of an atomic magnetometer in an external field according to claim 3, characterized in that, The three-axis rotary table is made of polyimide plastic, and the calibration rotary table is fixed with plastic or nylon screws.

5. The method for testing the low-magnetic heading error of an atomic magnetometer in an external field according to claim 4, characterized in that, The universal joint drive rod is custom-made using polytetrafluoroethylene (PTFE).

6. The method for testing the low-magnetic heading error of an atomic magnetometer in an external field according to claim 5, characterized in that, The universal joint increases the distance between the calibration turntable and the three-axis servo motor to more than 2m.

7. The method for testing the low-magnetic heading error of an atomic magnetometer in an external field according to claim 6, characterized in that, The distance between the control computer and the calibration turntable is greater than or equal to 5m.

8. A system for testing the heading error of an atomic magnetometer in an external field with low magnetic field, characterized in that, The atomic magnetometer external field low magnetic heading error testing system uses the atomic magnetometer external field low magnetic heading error testing method as described in any one of claims 1 to 7 to perform heading error testing.

9. The atomic magnetometer external field low magnetic heading error testing system according to claim 8, characterized in that, The atomic magnetometer field low-magnetic heading error testing system includes a canopy, a calibration turntable, a universal drive rod, and a turntable control system. The turntable control system includes a control computer and a three-channel servo motor. The calibration turntable includes a reference magnetometer fixture, a magnetometer under test fixture, a three-axis turntable, a level, and a three-axis magnetoresistive field. The canopy provides shielding for the heading error test, ensuring test continuity after power-on. The magnetometer under test fixture is used to fix the magnetometer under test onto the three-axis turntable. The reference magnetometer fixture is used to fix the reference magnetometer outside the three-axis turntable, providing a reference magnetic field for the magnetometer under test during calibration testing. The magnetic field signals of the magnetometer under test and the reference magnetometer differ to eliminate the influence of common magnetic field interference sources in the field on the magnetic field. The level is used to stably install the three-axis turntable on the ground, providing a stable environment for magnetometer calibration; the three-axis magnetoresistive field is used to identify the direction of the geomagnetic field, and rotating the three-axis turntable aligns the sensitive axis of the atomic magnetometer with the direction of the geomagnetic field, avoiding the influence of the geomagnetic field tilt angle on the test results. The universal joint is used to connect the three-axis rotation mechanism of the three-axis turntable to the three-channel servo motor, and to transmit the motion of the three-channel servo motor to the three-axis turntable. The control computer is used to complete the automatic testing of the low magnetic heading error of the atomic magnetometer in the external field.

Images