CN110018229A - A kind of multichannel low frequency magnetic leakage signal wireless acquisition system based on STM32 - Google Patents

Abstract

The invention discloses a kind of multichannel low frequency magnetic leakage signal wireless acquisition system based on STM32, is made of carrier, SD card module, STM32 one-chip computer module, WiFi module, c-type magnetic core, coil, slider roller, copper foil shielding layer, Hall element array module, signal conditioning module, power module, host computer.STM32 single-chip microcontroller generates ac-excited signal, generates alternating electromagnetic field；Alternating electromagnetic field forms magnetic flux leakage when encountering ferrimagnet defect；When magnetic flux leakage acts on Hall element array, Hall element generates multiple-channel output electric signal；Electric signal is after conditioning, and one-chip computer module carries out multi-channel serial scanning sample to electric signal, and sampled data is sent to WiFi module in real time and is transmitted to host computer, while sending it to SD card module and being stored.Due to low frequency Magnetic Flux Leakage Inspecting technology, detection probe array and the advantage of wireless transmission, which has the advantages that detection efficiency is high, and detection leakage phenomenon is few, and flaw detection ability is good, has good use value and application prospect.

Description

A wireless acquisition system of multi-channel low frequency magnetic flux leakage signal based on STM32

technical field

The invention belongs to the field of low-frequency magnetic flux leakage signal acquisition systems and equipment, and in particular relates to a multi-channel low-frequency magnetic flux leakage signal wireless acquisition system based on STM32.

Background technique

In 1933, Zuschlug first pointed out the concept of using magnetic sensors to detect magnetic flux leakage; in 1947, Hanstings developed the first-generation defect magnetic flux leakage detection system, and then the society began to realize the value of magnetic flux leakage detection technology.

In 1980, Professor Yariv first proposed the research idea of using the magnetostrictive effect to measure weak magnetic fields, and predicted that the minimum detectable magnetic field could reach 1.6×10 ^-12 T through certain calculations and experiments. After that, the optical fiber weak magnetic field sensor entered a golden age of rapid development, and a large number of related researches have been reported.

The principle of low-frequency magnetic flux leakage detection is: the excitation coil of the external excitation source excites a lower-frequency electromagnetic field in space. The magnetic field penetrates the ferromagnetic material in the pressurized equipment and is conducted from one side to the other. In the position without wall thickness reduction and defects, the magnetic field on the surface of the ferromagnetic specimen is weak; in the position with wall thickness reduction and defects, the magnetic field lines are hindered by the defects, the magnetic field mutates, and some magnetic field lines overflow the ferromagnetic specimen, resulting in leakage magnetic field. At this time, the location of the defect can be judged by changing the intensity of the leakage magnetic field signal.

The low-frequency magnetic flux leakage signal detection technology is widely used, and the main application directions are ferromagnetic pressure-bearing equipment such as boilers and pressure pipes.

SUMMARY OF THE INVENTION

In view of the deficiencies of the prior art, the purpose of the present invention is to use the Hall element as the basis for the detection of the magnetic flux leakage signal, and to take the low-frequency signal generation of the system based on the STM32 single-chip microcomputer, the sampling of the multi-channel leakage magnetoelectric signals and the wireless transmission of the sampled data as the core. Multi-channel low-frequency magnetic flux leakage signal realizes wireless detection.

The present invention is realized by the following technical solutions: a multi-channel low-frequency magnetic flux leakage signal wireless acquisition system based on STM32, comprising a carrier (1), an SD card module (2), an STM32 single-chip microcomputer module (3), a WiFi module (4), C-shaped magnetic core (5), coil (6), sliding roller (7), copper foil shielding layer (8), Hall element array module (9), signal conditioning module (10), power module (11), upper position The machine (12); it is characterized in that: the carrier (1) moves on the ferromagnetic test piece to be tested through the sliding roller (7); the STM32 single-chip microcomputer module (3) is provided with a working voltage by the power supply module (11); the Hall element The array module (9) is connected with the signal conditioning module (10) through wires, the conditioned electrical signals are transmitted to the STM32 single-chip microcomputer module (3) through the wires, and the STM32 single-chip microcomputer module (3) performs multi-channel serial line scanning sampling; STM32 The single-chip microcomputer module (3) is connected to the SD card module (2) through wires to store digital signals; the STM32 single-chip microcomputer module (3) is connected to the WiFi module (4) through wires to wirelessly transmit digital signals to the host computer (12); the STM32 single-chip microcomputer module (3) Provide a 20Hz AC excitation signal for the coil (6).

The specific model of the STM32 microcontroller module (3) is STM32RCT6.

The specific model of the WiFi module (4) is ESP32, and uses UART for data communication with the STM32 microcontroller module (3).

The C-shaped magnetic core (5) uses manganese-zinc ferrite material.

The coil (6) uses copper enameled wire.

The Hall element array module (9) includes 2 rows and 8 columns (16 pieces) of Hall elements, which are regularly and symmetrically arranged on the bottom surface of the carrier (1) for detecting magnetic flux leakage signals.

The working principle of the invention is as follows: the STM32 single-chip microcomputer generates a low-frequency alternating current excitation signal, which is input to the coil on the magnetic core to drive the alternating electromagnetic field. According to the magnetic field distribution following the principle of minimum magnetoresistance, when the alternating electromagnetic field encounters a defect in a ferromagnetic material, since the magnetic permeability of the air at the defect is lower than that of the ferromagnetic material, the magnetic field line will first bypass the defect and pass under the defect until saturation. , and overflow the surface of the material, thereby forming a leakage magnetic field. When the leakage magnetic field acts on the Hall element array, the Hall element array generates multiple output electrical signals. After the generated electrical signals are amplified, filtered and other conditioning operations, the ADC sampling pin of the STM32 single-chip microcomputer module performs serial scanning and sampling on the input multi-channel electrical signals, and the sampled data is sent to the WiFi module in real time, and is transmitted back to the host through the WiFi module. , and will also send the data to the SD card module for storage.

The beneficial effects of the present invention are as follows: in the design of the present invention, the Hall element is used as the basis for the detection of the magnetic flux leakage signal, and the STM32 single-chip microcomputer is used as the system low-frequency signal generation, multi-channel leakage magnetic and electrical signal sampling and wireless transmission of the sampled data as the core. Multi-channel low frequency magnetic flux leakage signal realizes fast wireless detection. The system has the advantages of high detection efficiency, fast detection speed, less missed detection, good flaw detection ability, etc. It has strong innovation and practical value, and has good application prospects.

Description of drawings

Figure 1 is a schematic structural diagram of the present invention.

FIG. 2 is a schematic diagram of the principle of the present invention.

FIG. 3 is a schematic diagram of the structure of the Hall element array of the present invention.

FIG. 4 is a WiFi module of the present invention.

FIG. 5 is the SD card module of the present invention.

Detailed ways

As shown in Figure 2, a multi-channel low-frequency magnetic flux leakage signal wireless acquisition system based on STM32 consists of a carrier (1), an SD card module (2), an STM32 microcontroller module (3), a WiFi module (4), a C-type Magnetic core (5), coil (6), sliding roller (7), copper foil shielding layer (8), Hall element array module (9), signal conditioning module (10), power module (11), host computer ( 12); it is characterized in that: the carrier (1) moves on the tested ferromagnetic test piece through the sliding roller (7); the STM32 single-chip microcomputer module (3) is provided with working voltage by the power supply module (11); the Hall element array module (9) Connected to the signal conditioning module (10) through wires, the conditioned electrical signal is transmitted to the STM32 single-chip microcomputer module (3) through the wires, and the STM32 single-chip microcomputer module (3) performs multi-channel serial line scanning sampling; STM32 single-chip microcomputer module (3) Connect with SD card module (2) through wires to store digital signals; STM32 single-chip microcomputer module (3) is connected with WiFi module (4) through wires, and wirelessly transmit digital signals to the host computer (12); STM32 single-chip microcomputer module (3) ) provides a 20Hz AC excitation signal for the coil (6). It solves the problems that the existing low-frequency magnetic flux leakage detection system has low detection efficiency, cannot perform multi-channel measurement, and is inconvenient to use.

Claims (1)

1. A multi-channel low-frequency magnetic flux leakage signal wireless acquisition system based on STM32, consisting of a carrier (1), an SD card module (2), an STM32 microcontroller module (3), a WiFi module (4), and a C-type magnetic core (5) ), coil (6), sliding roller (7), copper foil shielding layer (8), Hall element array module (9), signal conditioning module (10), power supply module (11), host computer (12); its It is characterized in that: the carrier (1) moves on the ferromagnetic specimen to be tested by sliding the roller (7); the STM32 single-chip microcomputer module (3) is provided with working voltage by the power supply module (11); the Hall element array module (9) passes through the The wire is connected with the signal conditioning module (10), and the conditioned electrical signal is transmitted to the STM32 single-chip microcomputer module (3) through the wire, and the STM32 single-chip microcomputer module (3) performs multi-channel serial line scanning sampling; the STM32 single-chip microcomputer module (3) passes The wire is connected to the SD card module (2) to store digital signals; the STM32 microcontroller module (3) is connected to the WiFi module (4) through the wire, and the digital signal is wirelessly transmitted to the host computer (12); the STM32 microcontroller module (3) is a coil ( 6) Provide 20Hz AC excitation signal; the inner opening angle of the C-type magnetic core (5) is 270 degrees, the inner diameter is 47.5cm, the outer diameter is 57.5cm, and the width is 60cm; the diameter of the enameled wire of the coil (6) is 0.49mm, and the number of turns is 500 turns.