A full-automatic active magnetic compensation method for a magnetic shielding cabin based on a sequential compensation algorithm

Abstract

The application relates to a full-automatic active magnetic compensation method of a magnetic shielding cabin based on a sequential compensation algorithm. The method can sequentially compensate the magnetic fields in three-axis directions in full automation, first, three-axis fluxgate sensors measure the sizes of the residual magnetic fields in three-axis directions in the magnetic shielding cabin, first, the direction of the maximum residual magnetic field is compensated, a control module controls compensation coils in the direction to generate a compensation magnetic field with equal size and opposite direction according to the size of the residual magnetic field in the direction and the coil constant of the compensation coils, after compensation in the direction, the magnetic fields in the other two directions are sequentially compensated in the same way, after compensation in the three directions is completed, the compensation effect is judged, if the residual magnetic field in the magnetic shielding cabin is in an ideal range, the three-axis coils output stable compensation currents, if the residual magnetic field after compensation is not in the ideal range, the above steps are repeated until the residual magnetic field in the magnetic shielding cabin reaches ideal requirements. The method can solve the problems of low compensation precision, complicated operation, long adjustment time and the like of manual compensation.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of active magnetic compensation in magnetic shielding cabin, and particularly relates to a full-automatic active magnetic compensation method for magnetic shielding cabin based on a sequential compensation algorithm. BACKGROUND

[0002] There are many physical quantities in life, among which the magnetic field is an important one. The magnetic field has wide applications in geophysics, material science, life medicine and production and life, and the heart magnet and the brain magnet are one of the important applications. The size of the heart magnet and the brain magnet is several tens of femtotes, and thus the measurement thereof requires an extremely low magnetic field environment. In the general geomagnetic environment, the size of the magnetic field is 50,000 nT, which is six orders of magnitude higher than that of the heart magnet and the brain magnet. There are also many interference magnetic fields in the environment, and the size of the interference magnetic field is also several orders of magnitude higher than that of the heart magnet and the brain magnet. Therefore, the measurement of the heart magnet and the brain magnet needs to be carried out in a general magnetic shielding cabin.

[0003] However, the residual magnetic field of the general magnetic shielding cabin after shielding is several tens of nT, which is far from the measurement environment of the heart magnet and the brain magnet, and thus active magnetic field compensation needs to be carried out in the magnetic shielding cabin. The traditional magnetic compensation method is a manual magnetic compensation method using a cross-modulation three-axis magnetic compensation method. The method needs three signal generators as the basis, and the magnetic field information output by the three-axis fluxgate sensor is observed through an oscilloscope to determine whether the residual magnetic field in the magnetic shielding cabin is compensated to zero. If the residual magnetic field after compensation is not zero, the step size is given according to the size of the residual magnetic field based on experience to adjust the output current of the signal generator, so that the residual magnetic field in the magnetic shielding cabin is compensated to zero. This method is a manual magnetic compensation method, and has problems of low compensation accuracy, complicated operation and long adjustment time. Therefore, it is of great significance to study a method for automatically and accurately compensating the magnetic field. SUMMARY

[0004] In order to solve the problems of complicated operation, long compensation time and low accuracy caused by the manual magnetic compensation method of the traditional magnetic shielding cabin, which needs to observe the output of the magnetic sensor through signal generators, oscilloscopes and other instruments and give the step size based on experience to adjust the compensation axis magnetic field, the application provides a full-automatic active magnetic compensation method for the magnetic shielding cabin based on a sequential compensation algorithm, which can automatically and quickly compensate the residual magnetic field in the magnetic shielding cabin to zero magnetic state, and provide a near-zero magnetic environment for subsequent work.

[0005] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0006] A full-automatic active magnetic compensation method for the magnetic shielding cabin based on a sequential compensation algorithm, comprising the following steps:

[0007] Step (1): First, the triaxial magnetic flux gate sensor is used to determine the magnetic field size in the magnetic shielding cabin in the three-axis direction, find the direction with the largest magnetic field size, and record it as the X-axis direction. The remaining two directions are recorded as the Y-axis and Z-axis directions.

[0008] Step (2): According to the X-axis direction magnetic field size obtained in step (1) and the coil constant of the X-axis compensation coil, the X-axis compensation coil generates an opposite compensation current to compensate the magnetic field in the X-axis direction. Then enter the Y-axis direction magnetic compensation.

[0009] Step (3): According to the Y-axis direction magnetic field size obtained in step (1) and the coil constant of the Y-axis compensation coil, the Y-axis compensation coil generates an opposite compensation current to compensate the magnetic field in the Y-axis direction. Then enter the Z-axis direction magnetic compensation.

[0010] Step (4): According to the Z-axis direction magnetic field size obtained in step (1) and the coil constant of the Z-axis compensation coil, the Z-axis compensation coil generates an opposite compensation current to compensate the magnetic field in the Z-axis direction.

[0011] Step (5): Determine whether the residual magnetic field size B in the magnetic shielding cabin after magnetic compensation is less than or equal to B0, where B0 is the ideal residual magnetic field size in the magnetic shielding cabin; where Bx is the residual magnetic field size after X-axis direction compensation in step (2), By is the residual magnetic field size after Y-axis direction compensation in step (3), and Bz is the residual magnetic field size after X-axis direction compensation in step (4). If B is less than or equal to B0, the X-axis compensation coil, Y-axis compensation coil and Z-axis compensation coil output stable compensation current. If B is greater than B0, repeat steps (2), (3) and (4) until B is less than or equal to B0.

[0012] Through the above five steps, the magnetic shielding cabin is quickly and automatically compensated in the three-axis sequence.

[0013] Further, in steps (2), (3) and (4), the current size corresponding to the magnetic field generated by the compensation coil is written into the system control part according to the coil constant of the compensation coil.

[0014] Further, in step (5), the size of B0 is set according to the use environment in the magnetic shielding cabin.

[0015] Compared with the prior art, the application has the advantages that: the full-automatic active magnetic compensation method based on the sequential compensation algorithm is designed, compared with the traditional manual compensation method, the output residual magnetism of the magnetic sensor is observed by an oscilloscope, a rough estimate is made, and the step size is given according to experience to adjust the compensation shaft magnetic field, the artificial cost is greatly reduced, the compensation speed is accelerated, and the compensation precision is improved, in addition, without the help of signal generators, oscilloscopes and other instruments, the system volume is reduced, the compensation data is more accurate, and the human reading error is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0016] The application can be better understood and the advantages thereof can be more clearly perceived by reference to the following detailed description when considered in connection with the following drawings, wherein:

[0017] Figure 1 A system schematic diagram of the full-automatic active magnetic compensation method based on the sequential compensation algorithm of the magnetic shielding cabin of the application;

[0018] Figure 2 A hardware system block diagram of the full-automatic active magnetic compensation method based on the sequential compensation algorithm of the magnetic shielding cabin of the application;

[0019] Figure 3 An algorithm flowchart of the full-automatic active magnetic compensation method based on the sequential compensation algorithm of the magnetic shielding cabin of the application. Specific implementation method

[0020] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative effort belong to the protection scope of the application.

[0021] The full-automatic active magnetic compensation method based on the sequential compensation algorithm of the magnetic shielding cabin of the application does not need to use signal generators and oscilloscopes and other instruments, and sequentially and automatically performs three-axis magnetic compensation based on a hardware system including a three-axis fluxgate sensor, an amplification and filtering module, an A / D data acquisition module, a DSP control module, a D / A data output module, a power amplification module, a current source module and a three-axis compensation coil. Firstly, the three-axis fluxgate sensor measures the sizes of the residual magnetic fields in three-axis directions of the magnetic shielding cabin, judges the direction of the maximum residual magnetic field and performs magnetic field compensation on the direction of the maximum residual magnetic field. The control module controls the compensation coil in the direction to generate a compensation magnetic field with the same size and opposite direction according to the size of the residual magnetic field in the direction and the coil constant of the compensation coil. After the compensation in the direction is completed, the residual magnetic fields in the remaining two directions are sequentially compensated in the same way. After the compensation in the three directions is completed, the compensation effect is judged. If the compensated residual magnetic field is in the ideal range, the three-axis coil outputs a stable compensation current. If the compensated residual magnetic field does not meet the ideal requirement, the above steps are repeated until the residual magnetic field in the magnetic shielding cabin reaches the ideal requirement. The application realizes full-automatic three-axis sequential magnetic field compensation, greatly reduces the labor cost compared with the traditional manual magnetic compensation, has faster compensation speed, simple operation and small hardware device volume.

[0022] As shown in Figure 1 The full-automatic active magnetic compensation method based on the sequential compensation algorithm of the magnetic shielding cabin of the application first defines the three-axis coil directions as X, Y and Z axes according to the sizes of the three-axis residual magnetic fields of the magnetic shielding cabin. The hardware system for realizing the application includes a magnetic shielding cabin 1, an X-axis compensation coil 2, a Y-axis compensation coil 3, a Z-axis compensation coil 4, a three-axis fluxgate sensor 5 and a hardware system control processing part 6. The X-axis compensation coil 2, the Y-axis compensation coil 3 and the Z-axis compensation coil 4 are located on the inner wall of the magnetic shielding cabin 1. The winding direction of a pair of coils of the X-axis compensation coil 2 is the same clockwise or counterclockwise, the winding direction of a pair of coils of the Y-axis compensation coil 3 is the same clockwise or counterclockwise, and the winding direction of a pair of coils of the Z-axis compensation coil 4 is the same clockwise or counterclockwise. The three-axis fluxgate sensor 5 is located at the center of the magnetic shielding cabin 1, and the hardware system control processing part 6 is located outside the magnetic shielding cabin 1 and connected with the three-axis fluxgate sensor 5 at the center of the magnetic shielding cabin 1 and the X-axis compensation coil 2, the Y-axis compensation coil 3 and the Z-axis compensation coil 4. The magnetic shielding cabin 1 has a cuboid structure.

[0023] As shown in Figure 2As shown, the hardware system control and processing section includes a three-axis fluxgate sensor, an amplification and filtering module, an A / D data acquisition module, a DSP control module, a D / A data output module, a power amplifier module, a current source module, and a three-axis compensation coil. This replaces instruments such as signal generators and oscilloscopes used for manual magnetic field compensation. First, the three-axis fluxgate sensor 5 measures the residual magnetic field within the magnetic shielding cabin 1. The signal is then transmitted to the DSP control module via the amplification and filtering module and the A / D data acquisition module. The DSP control module outputs a compensation voltage based on the magnitude of the residual magnetic field and the coil constant of the compensation coil. The signal then passes through the D / A data output module and the power amplifier module to the current source module. The current source module then outputs a compensation current based on the compensation voltage to the three-axis compensation coil. The three-axis compensation coil then generates a compensation magnetic field, and the three-axis fluxgate sensor 5 again measures the residual magnetic field within the magnetic shielding cabin 1.

[0024] like Figure 3 As shown, the present invention provides a fully automatic active magnetic compensation method for a magnetic shielding cabin based on a sequential compensation algorithm, and its specific implementation method includes the following steps:

[0025] Step (1): First, use the three-axis fluxgate sensor 5 to measure the direction of the largest residual magnetic field in the three-axis directions in the magnetic shielding cabin 1, which is recorded as the X-axis direction, and the remaining two directions are recorded as the Y-axis and Z-axis directions, where the residual magnetic field in the Y-axis direction is greater than the residual magnetic field in the Z-axis direction; and initialize the DSP control module, and write the coil constant relationship corresponding to the X-axis compensation coil 2, the Y-axis compensation coil 3 and the Z-axis compensation coil 4 into the DSP control module.

[0026] Step (2): Magnetic field compensation is first performed on the X-axis direction. The three-axis fluxgate sensor 5 is used to measure the magnitude of the residual magnetic field in the X-axis direction inside the magnetic shielding cabin 1. The magnitude of the residual magnetic field is input to the DSP control module through the amplification and filtering module and the A / D data acquisition module. The DSP control module outputs a compensation voltage based on the magnitude of the residual magnetic field and the magnetic field-voltage relationship set according to the coil constant of the X-axis compensation coil. The compensation voltage enters the current source module through the D / A data output module and the power amplifier module. The current source module outputs a compensation current to the X-axis compensation coil 2 based on the input compensation voltage to compensate for the residual magnetic field in the X-axis direction, and then enters the Y-axis magnetic field compensation.

[0027] Step (3): the residual magnetic field in the Y-axis direction in the magnetic shielding cabin 1 is measured by the three-axis fluxgate sensor 5, and is filtered and amplified by the amplification and filtering module and the A / D data acquisition module. The residual magnetic field is transmitted to the DSP control module, and the DSP control module outputs a compensation voltage according to the relationship between the magnetic field and the voltage set according to the coil constant of the Y-axis compensation coil. The compensation voltage is transmitted to the current source module through the D / A data output module and the power amplification module, and the current source module outputs a compensation current to the Y-axis compensation coil 3 to compensate the residual magnetic field in the Y-axis direction, and then the Z-axis direction magnetic field compensation is entered.

[0028] Step (4): the residual magnetic field in the Z-axis direction in the magnetic shielding cabin 1 is measured by the three-axis fluxgate sensor 5, and is filtered and amplified by the amplification and filtering module and the A / D data acquisition module. The residual magnetic field is transmitted to the DSP control module, and the DSP control module outputs a compensation voltage according to the relationship between the magnetic field and the voltage set according to the coil constant of the Z-axis compensation coil. The compensation voltage is transmitted to the current source module through the D / A data output module and the power amplification module, and the current source module outputs a compensation current to the Z-axis compensation coil 3 to compensate the residual magnetic field in the Z-axis direction.

[0029] Step (5): after the residual magnetic field compensation in the X-axis, Y-axis and Z-axis directions, the DSP control module judges the compensation effect. The DSP control module calculates whether the residual magnetic field B is less than or equal to B0, wherein B0 is the ideal residual magnetic field size in the magnetic shielding cabin, and the size is determined according to the use environment in the magnetic shielding cabin, wherein Bx is the residual magnetic field size after compensation in the X-axis direction in step (2), wherein By is the residual magnetic field size after compensation in the Y-axis direction in step (3), and wherein Bz is the residual magnetic field size after compensation in the X-axis direction in step (4); if B is less than or equal to B0, the X-axis compensation coil 2, the Y-axis compensation coil 3 and the Z-axis compensation coil 4 output stable compensation current, and if B is greater than B0, steps (2), (3) and (4) are repeated until B is less than or equal to B0.

[0030] The contents not described in detail in the specification of the present application belong to the prior art known to those skilled in the art.

[0031] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application, and is not used to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A full-automatic active magnetic compensation method based on a sequential compensation algorithm for a magnetic shielding cabin, characterized in that, Firstly, the triaxial fluxgate sensor measures the size of the residual magnetic field in the three-axis direction of the magnetic shielding cabin, judges the direction of the maximum residual magnetic field and performs magnetic field compensation on the direction of the maximum residual magnetic field; the control module controls the compensation coil in the direction to generate a compensation magnetic field with the same size and opposite direction according to the size of the residual magnetic field in the direction and the coil constant of the compensation coil; after the compensation in the direction is completed, the residual magnetic fields in the remaining two directions are sequentially compensated in the same way; after the compensation in the three directions is completed, the compensation effect is judged; if the compensated residual magnetic field is within the ideal range, the triaxial coil outputs stable compensation current; if the compensated residual magnetic field does not meet the ideal requirement, the steps are repeated until the residual magnetic field in the magnetic shielding cabin meets the ideal requirement; the method comprises the following steps: Step 1: First, the triaxial magnetic flux gate sensor is used to judge the magnetic field size in the magnetic shielding cabin in the three-axis direction, find the direction with the largest magnetic field size, and mark it as X axis direction, and the remaining two directions are marked as Y axis, Z axis direction, and initialize the DSP control system to X axis compensation coil, Y axis compensation coil and Z axis compensation coil corresponding to the coil constant relationship is written into the DSP control system; Step 2: The magnetic field in the axial direction is compensated by the axial compensation coil. X The axial magnetic field is compensated by the axial compensation coil. X The axial compensation coil has a coil constant. X The axial compensation coil generates a compensating current in the opposite direction to the magnetic field. X The axial magnetic field is compensated; then the magnetic field in the axial direction is compensated. Y The axial magnetic field is compensated. Step 3: The compound obtained in Step 1 above is reacted with Y The axial magnetic field size and Y The coil constant of the axial compensation coil, Y The axial compensation coil generates a reverse compensation current to Y Compensate the axial magnetic field; Then enter Z Magnetic compensation in axial direction; Step 4: The compound obtained in Step 1 above Z The axial magnetic field size and Z The coil constant of the axial compensation coil, Z The axial compensation coil generates an opposite compensation current to Z Compensate the axial magnetic field; Step 5: Determine the magnitude of the residual magnetic field after magnetic compensation in the magnetic shielding cabin B Is it less than or equal to B 0, where B 0 is the ideal residual magnetic field size in the magnetic shielding cabin; ,in Bx For step 2 X The magnitude of the residual magnetic field after axial direction compensation, By For step 3 Y The magnitude of the residual magnetic field after axial direction compensation, Bz For step 4 X The magnitude of the residual magnetic field after axial direction compensation; If B less than or equal to B 0, X the axial compensation coil, Y the axial compensation coil and Z the axial compensation coil outputs a stable compensation current, if B greater than B 0, steps 2, 3 and 4 are repeated until B less than or equal to B 0.

2. The full-automatic active magnetic compensation method for the magnetic shielding cabin based on the sequential compensation algorithm according to claim 1, characterized in that, The step 5 is described as follows, B 0The size of the setting is determined according to the use environment in the magnetic shielding cabin.

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