Three-axis magnetic sensor performance detection system

Abstract

A triaxial magnetic sensor performance detection system is characterized in that an industrial personal computer is connected with a group of A / D conversion modules and two groups of D / A conversion modules, and the group of A / D conversion modules is connected with a tested sensor installed on a test tool or a non-magnetic lifting platform; one group of D / A conversion modules is connected with three groups of high-precision current-stabilized power supplies; the D / A conversion module is connected with the three high-precision compensation power supplies, and the three high-precision current stabilization power supplies and the three high-precision compensation power supplies are connected with the three-axis Helmholtz coil. The three-axis Helmholtz coil matched with the device adopts the design of a main coil and an auxiliary coil, the electromagnetic coefficient of the main coil is relatively large, and a wide-range magnetic field simulation test is met. The electromagnetic coefficient of the secondary coil is small, the precision of magnetic field simulation is improved, and a space interference magnetic field is compensated in a real-time closed-loop mode. By designing a reasonable high-precision steady-current power supply conversion coefficient and coil parameters, the magnetic field simulation precision and the sensor performance calibration precision of the system device in an office are effectively improved. And the high-precision power supply is matched with the high-resolution and high-synchronism data acquisition module, so that higher-precision three-axis magnetic field simulation and measurement are realized. Meanwhile, the linearity index of the designed high-precision steady-current power supply can reach 0.002%.

Description

Technical Field

[0001] The utility model belongs to the technical field of index calibration, and relates to the calibration of the main performance indexes of magnetic sensors or magnetic fuzes. Specifically, it relates to a performance detection system for three-axis magnetic sensors. Background Technique

[0002] At present, the existing performance detection systems for three-axis magnetic sensors can simulate magnetic fields in any three components. Within the geomagnetic simulation range (±70uT), the magnetic field simulation accuracy is generally 10nT in ordinary offices or factories. There are no good suppression measures for the strong industrial frequency 50HZ and its harmonic interference indoors. At the same time, for the slow magnetic field fluctuations around, the magnetic field simulation system cannot be suppressed. Usually, the performance detection system for three-axis magnetic sensors is placed indoors where it is open and there is no strong magnetic interference around, and the installation environment requirements are relatively harsh. At the same time, for higher-precision magnetic field simulation, testers will choose to work late at night. At this time, the environmental interference is small and the surrounding magnetic field environment is relatively stable. There are requirements for the working hours of testers, and it is not suitable for long-term batch production and scientific research.

[0003] At the same time, there is currently no calibration measurement device that can automatically control various indicators of the sensor through automation. The various indicators of the magnetic sensor are manually measured through standard instrument equipment, and the data is recorded and analyzed to give a test report. The degree of automation for batch production and performance research is low and the efficiency is low. At the same time, the sampling rates of standard instrument equipment are relatively low, the reduction degree of test signals is relatively low, and the linearity index of the system is 0.01%. Summary of the Invention

[0004] In order to overcome the above deficiencies of the prior art, improve the accuracy of magnetic field simulation, suppress the industrial frequency and its harmonic interference and sporadic magnetic field fluctuations in the space environment, and improve the testing efficiency of the sensor, the purpose of the utility model is to provide a performance detection system for three-axis magnetic sensors, which uses magnetic sensor test software to automatically control hardware devices to complete the testing of various performance indicators of the sensor or magnetic fuze, and automatically records the test data to generate a test report, effectively improving the efficiency of batch production of magnetic sensors.

[0005] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0006] A performance detection system for three-axis magnetic sensors includes an industrial control computer. Its characteristic is that the industrial control computer is connected to a group of A / D conversion modules and two groups of D / A conversion modules. One group of A / D conversion modules is linked to the magnetic sensor installed on the test tooling or the non-magnetic lifting platform; one group of D / A conversion modules is connected to three groups of high-precision constant current power supplies; one group of D / A conversion modules is connected to three groups of high-precision compensation power supplies, and the three groups of high-precision constant current power supplies and the three groups of high-precision compensation power supplies are respectively connected to the three-axis Helmholtz coils.

[0007] The described three-axis Helmholtz coil consists of a main coil and an auxiliary coil. Coils A (1) and B (2) are installed in parallel as the X-axis coil, coils C (3) and D (4) are installed in parallel as the Y-axis coil, and coils E (5) and F (6) are installed in parallel as the Z-axis coil. The X-axis, Y-axis, and Z-axis coils are orthogonally combined to form a three-axis Helmholtz coil.

[0008] The described three-axis Helmholtz coil is made of non-metallic epoxy board material.

[0009] The described high-precision constant current power supply is connected in sequence with a 220VAC power supply filter, a toroidal transformer, a current amplification circuit, and a rectifier circuit. One path of the rectifier circuit is connected to a low-noise operational amplifier, and the other path is connected to a power amplifier. The low-noise operational amplifier is connected to the power amplifier, the power amplifier is connected to a 0.2ppm low-temperature drift sampling resistor, the 0.2ppm low-temperature drift sampling resistor is connected to the three-axis Helmholtz coil, and the low-noise operational amplifier receives signal input.

[0010] The beneficial effects of the present utility model are:

[0011] The present utility model belongs to a calibration device for the main performance indicators of magnetic sensors or magnetic fuzes, and can realize the calibration and measurement of indicators such as the range, sensitivity, DC linearity, AC linearity, frequency response, orthogonality, time-domain noise, frequency-domain noise, zero bias, and stability of the product under test. The system can measure or calibrate mature mass-produced magnetic sensors, and can also test and verify the performance of magnetic fuze products, improve production efficiency, and assist in the research and demonstration of scientific research products.

[0012] In addition to calibrating the performance indicators of sensors or magnetic fuzes, the device of the present utility model can also simulate the magnetic field components at any location in the world according to the IGRF13 model. At the same time, the real-time closed-loop feedback control is used to improve the indoor magnetic field simulation accuracy.

[0013] The three-axis Helmholtz coil supporting this device adopts a main and auxiliary coil design. The main coil has a larger electromagnetic coefficient, which meets the requirements of large-range magnetic field simulation tests. The auxiliary coil has a smaller electromagnetic coefficient, which improves the accuracy of magnetic field simulation and the real-time closed-loop compensation of spatial interference magnetic fields. By designing reasonable conversion coefficients of the high-precision constant current power supply and coil parameters, the magnetic field simulation accuracy of the system device in the office and the sensor performance calibration accuracy are effectively improved. The high-precision power supply is combined with a high-resolution and high-synchronization data acquisition module to achieve higher-precision three-axis magnetic field simulation and measurement. At the same time, the designed linearity index of the high-precision constant current power supply can reach 0.002%.

[0014] This device mainly solves the efficiency problem in the mass production of magnetic sensors or magnetic fuzes and improves the accuracy of magnetic field simulation. The software controls and automatically calibrates and measures the indicators of the sensor or magnetic fuze under test, such as range, sensitivity, DC linearity, AC linearity, frequency response, orthogonality, time-domain noise, frequency-domain noise, zero offset, and stability. After the test, a test report is automatically generated. Indicators such as time-domain noise, frequency-domain noise, zero offset, and stability of magnetic sensors or magnetic fuzes can be tested on multiple sets of equipment simultaneously. By placing a structural tooling for installing multiple sets of equipment in the supporting magnetic shielding barrel, the space inside the magnetic shielding barrel is fully utilized, which is of great significance for improving the efficiency of mass production and shortening the product development time.

[0015] In this device, the accuracy and stability of magnetic field simulation are determined by the output current accuracy and stability of the high-precision constant-current power supply and the high-precision compensation power supply. Therefore, the current characteristics of the power supply directly determine the accuracy of system magnetic field simulation and the accuracy of sensor performance detection. The high-precision constant-current power supply and the high-precision compensation power supply adopt a linear power supply design. An annular transformer is used inside to provide a stable and low-noise voltage for the power amplifier inside the power supply. The input voltage signal is amplified by multiple low-noise operational amplifiers and processed by a high-voltage and high-current power operational amplifier, and then a stable current is output. The circuit is designed in a constant-current source mode, and the output current is feedback through a 0.2ppm low-temperature-drift high-precision resistor to ensure the accuracy and stability of the power supply output current. After testing, the current output accuracy of the high-precision constant-current power supply and the high-precision compensation power supply is better than 0.05mA. The output current stability of the 2A output of the high-precision constant-current power supply is better than 0.2mA@3h, and the output current stability of the 0.5A output of the high-precision compensation power supply is better than 0.1mA@3h. The high precision of the power supply effectively improves the control precision of the system and ensures the accuracy of various test indicators.

[0016] Through actual test verification, this device can achieve high-precision indicator measurement of the sensor under test in the office. The actual verification test shows that the linearity of the magnetic sensor is better than 0.002%, the sensitivity is better than 0.05%FS, and the orthogonality is better than 0.05°. The system magnetic field simulation accuracy is better than 0.5nT, the magnetic field closed-loop control simulation accuracy can reach within 4nT, and the power frequency interference and low-frequency interference are effectively attenuated by more than 30dB.

[0017] Through the software IGRF13 model, the system can simulate and generate the magnetic field intensity at any point in the world in a closed-loop control indoors, and the magnetic field simulation results are accurate and reliable. Furthermore, it can be extended to realize magnetic anomaly vector simulation and magnetic simulation experiments with different passing characteristics.

[0018] This device provides a stable and high-precision magnetic field value for magnetic field simulation through a high-precision linear constant-current power supply design and the main and auxiliary coil design structures. Thus, it provides reliable results for the performance index detection of magnetic sensors or magnetic fuzes in an office environment. It provides a stable magnetic field environment under the condition of ambient magnetic field interference indoors, reducing the influence of interference on the accuracy of measurement results. Brief Description of the Drawings

[0019] Figure 1 It is a schematic structural diagram of the present utility model.

[0020] Figure 2 It is a schematic system diagram of the present utility model.

[0021] Figure 3 It is a circuit diagram of the high-precision constant-current power supply of the present utility model.

[0022] Among them, 1 is coil A, 2 is coil B, 3 is coil C, 4 is coil D, 5 is coil E, and 6 is coil F. Detailed Implementation Manner

[0023] As Figure 1 shown, the performance detection system of the three-axis magnetic sensor of this device consists of hardware and software. The system hardware includes a three-axis fluxgate magnetic sensor, a three-axis Helmholtz coil, a non-magnetic lifting platform, a high-precision constant-current power supply, a high-precision compensation power supply, a data acquisition box (including a 16-bit high-precision D / A conversion module and a 24-bit high-precision A / D acquisition module), a magnetic shielding cylinder, an industrial control computer, and a display. At the same time, through Figure 2 the test structure tooling in it, 8 sensors can be measured simultaneously, improving the test production efficiency.

[0024] The performance detection system of the three-axis magnetic sensor of this device consists of hardware and software. The system software is installed on the industrial control computer to control the hardware device to automatically complete the measurement and calibration of different indicators of the magnetic sensor. The system hardware includes a three-axis fluxgate magnetic sensor, a three-axis Helmholtz coil, a non-magnetic lifting platform, a high-precision constant-current power supply, a high-precision compensation power supply, a data acquisition box (including a 16-bit high-precision D / A conversion module and a 24-bit high-precision A / D acquisition module), a magnetic shielding cylinder, an industrial control computer, and a display.

[0025] Figure 1The system software is installed on the industrial control computer, which controls the D / A conversion module to generate signals. The signals are amplified by the high-precision constant-current power supply and output as current to drive the three-axis Helmholtz main coil to generate a DC magnetic field or an AC magnetic field. The magnetic sensor under test is placed on a non-magnetic lifting platform at the center of the coil. The function of the non-magnetic lifting platform is to ensure that the object under test is at the center of the uniform area of the coil. The voltage signal output by the magnetic sensor is processed by the A / D acquisition module and connected to the industrial control computer through USB. The software reads the acquired data, displays it in real time, and calculates through algorithms to give the test results of various indicators of the sensor. During the stable magnetic field test process, the software controls the D / A conversion module to generate a compensation voltage signal, which is amplified by the high-precision compensation power supply and output to drive the secondary coil to generate a compensation magnetic field, canceling the power frequency interference or accidental magnetic field interference, ensuring that the magnetic field fluctuation in the uniform area of the coil is small, and meeting the magnetic field test accuracy requirements of the product under test.

[0026] Figure 1 In this device, multiple magnetic sensors or magnetic fuze products can be placed on the test fixture inside the magnetic shielding barrel. Up to 8 magnetic sensors can be placed, and there is a certain spacing between each sensor to avoid mutual interference. The output voltage signals of multiple sensors are processed by the 24-bit high-synchronization and high-sampling-rate A / D acquisition module in the data acquisition box and connected to the industrial control computer through a USB cable, so as to realize the measurement and calibration of indicators such as time-domain noise, frequency-domain noise, zero bias, and stability of multiple sensors, and generate a test report.

[0027] Figure 2 The figure shows the internal circuit design block diagram of the system's high-precision constant-current power supply or high-precision compensation power supply. The device inputs 220VAC voltage, which is output as positive and negative dual-channel DC voltage through an EMI filter, a toroidal transformer, a current-boosting circuit, and a rectifier circuit, providing operating voltage for the low-noise operational amplifier and power amplifier circuits. The analog signal input to the power supply is processed by the low-noise operational amplifier and power amplifier circuits, and a constant current signal is output. The current signal output by the power supply is fed back to the power amplifier through a 0.2ppm low-temperature-drift and high-precision sampling resistor to ensure the constancy of the working current of the driving load coil.

[0028] Figure 3 The figure shows the structural design diagram of the system's three-axis Helmholtz coil. The main and secondary coils are designed with the same frame and size, which simplifies the structure and reduces the processing cost, and the orthogonality of the installed coil frame is better. The coil is machined and designed using non-metallic epoxy board material, and both the strength and accuracy can be guaranteed. Figure 3 Coils 1 and 2 have the same size and are installed in parallel, which is the X-axis of the coil. Coils 3 and 4 have the same size and are installed in parallel, which is the Y-axis of the coil. Coils 5 and 6 have the same size and are installed in parallel, which is the Z-axis of the coil. The X-axis, Y-axis, and Z-axis coils are mutually orthogonal, forming a three-axis Helmholtz coil.

[0029] To improve the magnetic field stability and the accuracy of magnetic field simulation, the high-precision compensation power supply supporting the system drives the secondary coil in real-time closed-loop to cancel out the magnetic field fluctuations in the test environment. To improve the stability and accuracy of simulation, accidental interference magnetic fields and power frequency and its multiple frequency interferences are cancelled out, and the magnetic field in the uniform area is ensured to be stable at the preset magnetic field intensity. A calibrated standard fluxgate sensor is placed at the center of the uniform area to detect the real-time magnetic field in the uniform area. If the detected magnetic field changes, the control software adjusts the output current of the high-precision compensation power supply in real time to achieve the corresponding compensation of the magnetic field, so that the simulated magnetic field is stable at the magnetic field intensity value under the simulation accuracy, thereby improving the measurement accuracy and accuracy of the product under test.

[0030] Among them, the supporting high-precision constant current power supply and high-precision compensation power supply are both linear power supplies, and the output current can reach 3A. The internal of the power supply adopts a toroidal transformer, a current expansion circuit, and a rectifier circuit to provide a low-ripple stable DC voltage for the low-noise operational amplifier and power amplifier on the power amplifier circuit board. The input voltage signal is processed by the operational amplifier and power amplification to output a stable current. The circuit design is in the constant current source mode, and the output current is feedback through a 0.2ppm low-temperature-drift high-precision resistor to ensure the accuracy and stability of the power supply output current. After testing, the current output accuracy of the high-precision constant current power supply and high-precision compensation power supply is better than 0.05mA, the stability of the 2A output current of the high-precision constant current power supply is better than 0.2mA@3h, and the stability of the 0.5A output current of the high-precision compensation power supply is better than 0.1mA@3h.

[0031] Through the design of the high-precision constant current power supply and high-precision compensation power supply, combined with a high-resolution 16-bit D / A conversion module, the current accuracy better than 0.05mA is achieved. Taking a Helmholtz coil with a side length of 1.8m as an example, the magnetic field simulation accuracy can be better than 0.5nT (taking the secondary coil of the Helmholtz coil simulating a magnetic field intensity of 9uT as an example), the magnetic field stability is better than 4nT (taking the main coil of the Helmholtz coil with an electromagnetic coefficient of 20uT magnetic field intensity as an example), the average value of the magnetic field simulated by the system's real-time closed-loop control is better than 1nT, and the dynamic fluctuation after canceling the interference is better than 20nT.

[0032] The supporting software processes and controls the output signal of the high-precision D / A module through a certain algorithm, and drives the three-axis Helmholtz coil through the high-precision constant current power supply to simulate a DC magnetic field or an AC magnetic field. The magnetic sensor under test is placed on a non-magnetic lifting platform at the center of the three-axis Helmholtz coil. The signal collected and output by it is processed by high-precision A / D acquisition. The upper computer software calculates the current magnetic field intensity and the performance index results of the magnetic sensor, and can save the magnetic field data to generate a test report. In the whole process of functional index testing, only the test personnel need to set reasonable system measurement parameters to automatically realize the performance detection of the sensor under test.

[0033] The compensation for magnetic field stability is achieved by driving the secondary coil with a high-precision compensation power supply. To improve the simulation accuracy, cancel the accidental interference magnetic field, power frequency and its multiple frequency interference, and ensure that the magnetic field in the uniform area is stable at the preset magnetic field intensity, a calibrated standard fluxgate sensor is placed at the center of the uniform area to detect the real-time magnetic field in the uniform area. If the detected magnetic field changes, the control software adjusts the output current of the high-precision compensation power supply in real time to achieve the corresponding compensation of the magnetic field, so that the simulated magnetic field is stable at the magnetic field intensity value under the simulation accuracy, thereby improving the measurement accuracy and accuracy of the product under test.

[0034] This device, in cooperation with a magnetic shielding barrel made of 5-layer permalloy material, can realize the measurement and calibration of indicators such as time-domain noise, frequency-domain noise, zero offset, and stability of the sensor under test or magnetic fuze.

[0035] Three sets of equipment of this device have been developed. The three-axis Helmholtz coils supporting the system are all square, with three side length specifications of 3m, 2m, and 1.8m. They can all simulate and generate a DC magnetic field intensity of ±100uT and an AC magnetic field intensity of not less than 10uT.

[0036] Taking the three-axis Helmholtz coil system with a side length of 1.8m as an example, the system has a geomagnetic cancellation function. By using closed-loop control, the environmental interference magnetic field can be cancelled. After cancellation, the magnetic field fluctuation in the uniform area is not greater than 20nT. The central uniform area of the three-axis Helmholtz coil is 200mm × 200mm × 200mm. The uniformity index of the uniform area is better than 0.5%, and the system linearity index can reach 0.002%. The system frequency response measurement range is DC~1kHz. It can realize the simulation and reproduction of the target measurement magnetic field and the system self-calibration function. The three-axis Helmholtz coils can be selected to work simultaneously or independently, and can realize the simulation of AC-DC superimposed magnetic fields. The system can test indicators such as AC linearity, DC linearity, frequency response, magnetic field range, positive angle, sensitivity coefficient, time-domain noise, frequency-domain noise, and zero offset of magnetic sensors.

Claims

1. A performance detection system for a three-axis magnetic sensor, including an industrial control computer, characterized in that, The industrial control computer is connected to a group of A / D conversion modules and two groups of D / A conversion modules. One group of A / D conversion modules is linked to the tested sensors installed on the test tooling or the non-magnetic lifting platform; one group of D / A conversion modules is connected to three groups of high-precision constant current power supplies; one group of D / A conversion modules is connected to three groups of high-precision compensation power supplies, and the three groups of high-precision constant current power supplies and the three groups of high-precision compensation power supplies are respectively connected to the three-axis Helmholtz coils.

2. The performance detection system of a three-axis magnetic sensor according to claim 1, characterized in that, The three-axis Helmholtz coils mentioned above are main and auxiliary coils. Coil A (1) and coil B (2) are installed in parallel as the coil X-axis, coil C (3) and coil D (4) are installed in parallel as the coil Y-axis, coil E (5) and coil F (6) are installed in parallel as the coil Z-axis. The coil X-axis, coil Y-axis, and coil Z-axis coils are orthogonally combined with each other to form the three-axis Helmholtz coils.

3. The performance detection system of a three-axis magnetic sensor according to claim 1, characterized in that The three-axis Helmholtz coils mentioned above are made of epoxy board non-metallic material.

4. A performance detection system for a three-axis magnetic sensor according to claim 1, characterized in that The high-precision constant current power supply is connected in sequence by filtering the 220VAC power supply to a toroidal transformer, a current expansion circuit, and a rectifier circuit. One path of the rectifier circuit is connected to a low-noise operational amplifier, and the other path is connected to a power amplifier. The low-noise operational amplifier is connected to the power amplifier. The power amplifier is connected to a 0.2ppm low-temperature drift sampling resistor. The 0.2ppm low-temperature drift sampling resistor is connected to the three-axis Helmholtz coils, and the low-noise operational amplifier receives signal input.

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