Electromagnetic resonance type high-frequency fatigue testing machine controller based on ARM

Abstract

The invention relates to an ARM-based electromagnetic resonant high-frequency fatigue testing machine controller, which belongs to the technical field of fatigue testing machines, and comprises a control module based on an ARM architecture, an AD acquisition module, a DA control module, a storage circuit module, a communication module and a power supply module, the control module is connected with the AD acquisition module and is used for acquiring data of a tension sensor and a pressure sensor of the testing machine; the control module is connected with the DA control module and outputs control signals of the hydraulic servo valve and the direct-current servo motor. The control module is connected with the storage circuit module and is used for storing log files and parameters of the sensor; the control module is connected with the communication module and is used for communicating with an upper computer or a remote handheld terminal; and the power supply module is used for supplying power to each module.

Description

Technical Field

[0001] The invention belongs to the technical field of fatigue testing machines, and relates to an electromagnetic resonance type high-frequency fatigue testing machine controller based on ARM. Background Art

[0002] The electromagnetic resonance high-frequency fatigue testing machine is mainly used for tensile, compression, tension-compression alternating loads and prefabricated crack and crack extension experiments. The difference from the low-frequency testing machine is that the working principle of the electromagnetic resonance high-frequency fatigue testing machine is to utilize the system resonance principle. It has the characteristics of simple operation, high efficiency, low energy consumption and high reliability. Therefore, it is widely used in various fields such as aviation, aerospace, scientific research in colleges and universities, and industrial production.

[0003] Previous low-end processors can no longer meet the requirements of the intelligent measurement and control system of the test machine. Specifically, the data processing ability cannot keep up with the large amount of data generated during the test, the interrupt method cannot meet the complex working conditions, and the peripheral support is insufficient. Other controllers using X86 processors are limited in application due to their high cost, high power consumption and slow processing speed. Summary of the invention

[0004] In view of this, the object of the present invention is to provide an electromagnetic resonance high frequency fatigue testing machine controller based on ARM.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] An ARM-based electromagnetic resonance high-frequency fatigue testing machine controller includes an ARM-based control module, an AD acquisition module, a DA control module, a storage circuit module, a communication module and a power supply module;

[0007] The control module is connected to the AD acquisition module to collect the tension and pressure sensor data of the testing machine;

[0008] The control module is connected to the DA control module and outputs control signals of the hydraulic servo valve and the DC servo motor;

[0009] The control module is connected to the storage circuit module and is used to store log files and sensor parameters;

[0010] The control module is connected to the communication module for communicating with the host computer or the remote handheld terminal;

[0011] The power supply module is used to supply power to each module.

[0012] Furthermore, the AD acquisition module includes an analog switch circuit, an instrumentation amplifier, a Butterworth low-pass filter, a single-ended signal to differential signal circuit and an AD conversion chip; the analog signal output by the sensor first enters the instrumentation amplifier through the analog switch for voltage amplification, then is filtered through the Butterworth low-pass filter, and then is converted into a differential signal using the single-ended signal to differential signal circuit, then enters the AD conversion chip to be converted into a digital signal, and finally is transmitted to the control module through the SPI bus.

[0013] Furthermore, the DA conversion module is composed of a 16-bit precision DA conversion chip and peripheral circuits. The digital signal sent by the control module is converted into an analog signal by the DA conversion chip and then used to control the servo DC motor to realize the static control function of the high-frequency fatigue testing machine.

[0014] Further, the communication module includes a USB communication module, a serial port module and an Ethernet module;

[0015] The USB communication module is used to connect to a USB flash drive to achieve firmware upgrade;

[0016] The serial port module includes two interfaces, RS232 and RS485; the RS232 interface is used to realize the debugging function; the RS485 interface is used to communicate with the remote handheld terminal;

[0017] The Ethernet module is used to connect to the host computer.

[0018] Furthermore, the storage circuit module includes an EEPROM.

[0019] Furthermore, the power module includes a DCDC circuit and an LDO circuit, wherein the DCDC circuit is used to convert the input 220V AC power into a 24V DC power supply; and the LDO circuit is used to provide differential and stable power supply to each module.

[0020] The beneficial effects of the present invention are as follows: the present invention adopts a control module based on the ARM architecture, which has the characteristics of excellent data processing capability, rich peripheral resources, reliable performance, low cost, low power consumption, etc. The accuracy is significantly improved. Through the continuous improvement of the signal conditioning circuit, the static load accuracy can currently reach within 0.5%, which meets the accuracy (0.5) required by the high-frequency testing machine controller industry. The controller realizes the automatic calibration function of the sensor through the analog switch. By reading the value of the sensor reference voltage and comparing it with the value of the actual signal of the sensor, the voltage value of the sensor signal attenuated on the long-distance transmission line can be further obtained, and the attenuated voltage can be compensated by the software algorithm. The stepless adjustment function of the filter cutoff frequency is realized, and the precise adjustment of the cutoff frequency of the Butterworth low-pass filter hardware circuit can be realized through the host computer according to the experimental frequency, which effectively suppresses the high-frequency interference signal in the signal link.

[0021] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0023] Figure 1 This is the controller system block diagram;

[0024] Figure 2 This is the schematic diagram of the signal conditioning circuit;

[0025] Figure 3 This is the schematic diagram of the AD module;

[0026] Figure 4 This is the schematic diagram of the DA module;

[0027] Figure 5 It is Ethernet and USB communication interface circuit;

[0028] Figure 6 It is a serial communication interface circuit;

[0029] Figure 7 For dynamic loading of signals;

[0030] Figure 8 Control accuracy for static loading. DETAILED DESCRIPTION

[0031] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0032] Among them, the drawings are only used for illustrative explanations, and they only represent schematic diagrams rather than actual pictures, and should not be understood as limitations on the present invention. In order to better illustrate the embodiments of the present invention, some parts of the drawings may be omitted, enlarged or reduced, and do not represent the size of actual products. For those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0033] The same or similar numbers in the drawings of the embodiments of the present invention correspond to the same or similar parts; in the description of the present invention, it should be understood that if the terms "upper", "lower", "left", "right", "front", "rear", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0034] Aiming at the deficiencies of traditional controllers, the present invention provides a design method for a high-frequency fatigue testing machine controller based on ARM, and designs a high-frequency fatigue testing machine controller with high reliability, high stability, intelligence and convenient operation.

[0035] The present invention is implemented through the following technical scheme: a high-frequency fatigue testing machine controller based on ARM includes a microprocessor control module, characterized in that: the microprocessor control module is connected to a high-precision AD acquisition module, a DA control module, a USB communication module, an RS232 / RS485 serial communication module, an Ethernet communication module, a storage circuit module and a power supply module.

[0036] The microprocessor control module is composed of an STM32H750 microprocessor chip, a clock circuit, a reset circuit, an SDRAM memory chip, an EEPROM, and a SWD interface circuit. The microprocessor control module is connected to the AD conversion chip via the SPI interface to collect data on the tension and pressure of the test machine; the microprocessor control module outputs control signals of the hydraulic servo valve and the DC servo motor by controlling the DA conversion chip; the microprocessor control module is connected to the USB communication module, and the USBHost mode is used to implement the remote firmware upgrade function of the U disk; the microprocessor control module implements controller debugging by connecting to the RS232 serial communication module, and implements the communication function with the remote handheld terminal through the RS485 serial port; the microprocessor control module transmits test data to the upper computer and receives control signals from the upper computer by connecting to the Ethernet module; the microprocessor control module is connected to the storage circuit module to store important information such as log files and sensor parameters generated during the operation of the controller; the power supply module is used to provide power for the entire controller system. The controller system block diagram is shown in the attached figure. Figure 1 shown.

[0037] The above-mentioned AD conversion module includes an analog switch circuit, an instrumentation amplifier, a filtering circuit, a single-ended signal to differential signal circuit and an AD conversion chip; the analog signal output by the sensor first enters the instrumentation amplifier through an analog switch for voltage amplification, then is filtered through a Butterworth low-pass filter and converted into a differential signal, and finally enters the AD conversion chip to be converted into a digital signal and transmitted to the microprocessor module through the SPI bus.

[0038] The above-mentioned DA conversion module consists of a 16-bit precision DA conversion chip and peripheral circuits. The digital signal sent by the microprocessor control module is converted into an analog signal by the DA conversion chip and used to control the servo DC motor to realize the static control function of the high-frequency fatigue testing machine.

[0039] The above-mentioned USB communication module is composed of a USB Type-A interface. The microcontroller works in the host mode and the firmware is upgraded through the USB flash drive.

[0040] The above serial port module uses two interfaces, RS232 and RS485. RS232 includes a serial port and a MAX232 power conversion chip, which mainly realizes the debugging function; RS485 includes a serial port and a MAX485 power conversion chip, which mainly realizes the communication function with a handheld terminal.

[0041] The above-mentioned Ethernet module is composed of an Ethernet control chip and a network port, and realizes the data exchange function between the lower computer and the upper computer.

[0042] The above-mentioned storage circuit module mainly includes an EEPROM, which is used to store important information such as log files generated during the operation of the controller and sensor parameters.

[0043] The power module includes a DCDC circuit and an LDO circuit. The input power of the entire controller is 220V AC, which is converted into 24V DC power by a 24VDCDC module and then input into the controller mainboard. The power modules on the mainboard mainly include 24V—±15V, +15V—+9V, -15V—-9VDCDC modules, and +9—+5V, -9V—-5V, +5V—+3.3VLDO modules.

[0044] Example 1

[0045] Figure 1 The figure shows a controller system block diagram, which is a high-frequency fatigue testing machine controller based on the ARM Cortex-M7 core, including a minimum system of an STM32H7 microcontroller 1, a signal conditioning and AD sampling circuit 2, a DA output module 3, a 100M Ethernet module 4, a USB communication module 5, a serial port module 6, a storage module 7, and a power module 8.

[0046] Figure 2 and Figure 3 They are the signal conditioning circuit and the AD sampling module. This part of the circuit includes an analog switch chip AD5209 (U42), an instrument amplifier AD8429 (U41), a fourth-order Butterworth switched capacitor filter TLC14CD (U43), a voltage amplifier OP2177 (U44), an audio power amplifier chip OPA1632 (AR1) and other peripheral circuits. In order to enable the controller to be used on an electro-hydraulic servo universal testing machine at the same time, one displacement sensor and one LVDT sensor signal acquisition channel are reserved in the circuit design. Therefore, the present invention selects AD7779 as the AD conversion chip. This chip can synchronously sample 8 sensor signals at the same time, and the sampling rate can reach 16kSPS. Figure 2As shown, the sensor signals F_S+, F_S- and ±10mV (full scale of the sensor) reference voltages F_refrence_A and F_refrence_B are selected through analog switches and pass through resistors R114 and R118 to enter the instrument amplifier U41. R117 is used to adjust the gain of the instrument amplifier. The amplified voltage output from pin 7 of U41 enters the Butterworth low-pass filter (U43). U43 is a fourth-order Butterworth switched capacitor filter. The PWM signal at pin 2 is generated by the MCU peripheral and is used to adjust the filter cutoff frequency. The relationship between the PWM frequency and the cutoff frequency is 100:1 (for example, if the PWM frequency is 10kHz, the cutoff frequency is 100Hz). U44 is connected in voltage follower mode to enhance the signal driving capability and input to the next-level audio amplifier AR1 to realize the conversion of single-ended signals into differential signals. At this point, the entire signal conditioning circuit has been introduced. The next step is to perform AD conversion on the conditioned signal, as shown in Figure 3 As shown, the conversion chip AD7779 is selected, and data is exchanged with the MCU via SPI.

[0047] Figure 4 This is the schematic diagram of the DA module. This part of the circuit includes a DA conversion chip LTC1668 (U2) and a converted analog voltage amplification circuit. The MCU outputs a 16-bit digital signal to the DA conversion chip through the IO port for analog-to-digital conversion. The converted analog voltage is output after deflection adjustment and step-by-step amplification. So far, the DA module circuit has been introduced.

[0048] Figure 5 The schematic diagram of Ethernet communication and USB communication module is shown. This part of the circuit includes an Ethernet PHY chip LAN8720A (U7), RJ45 connector, USB Type-A connector and other peripheral circuits. The controller of the present invention communicates with the host computer through 100M Ethernet. The MAC module is integrated inside the Ethernet peripheral of the MCU microcontroller. The MAC and PHY are connected through the RMII interface, which can save half of the data lines. The USB working mode is set to host mode to realize the function of local firmware upgrade.

[0049] Figure 6 The figure shows the serial communication module, which is mainly composed of RS232 voltage conversion chip (U8) and RS485 voltage conversion chip (U10) and corresponding peripheral circuits. The RS232 interface is used for serial debugging, and the RS485 interface is used to exchange data with a remote handheld terminal. In addition, it can also communicate with an external voltage driver to control the dynamic loading function of the high-frequency fatigue testing machine.

[0050] The sensor signal is processed by the signal conditioning circuit and then input into the AD conversion chip for data acquisition. The collected signal is input into the MCU microcontroller. After simple processing, it is transmitted to the host computer through the Ethernet communication module for visualization processing. At the same time, the host computer sends the corresponding control instructions to the MCU microcontroller. The MCU parses the instructions and executes the corresponding control logic to realize the static loading and dynamic loading control functions of the high-frequency fatigue testing machine.

[0051] Figure 7 , Figure 8 The figure shows the final effect achieved by the present invention. Figure 7 When the load is dynamic, the controller collects data and transmits it to the host computer for visualization. Figure 8 The figure shows the acquisition accuracy of the controller after the input signal is short-circuited, which simulates the static loading test. The results show that the static loading control accuracy of the controller can reach within 0.5% (the high-frequency fatigue testing machine requires a static loading control accuracy of 0.5%).

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. An electromagnetic resonance high frequency fatigue testing machine controller based on ARM, characterized in that: It includes a control module based on ARM architecture, an AD acquisition module, a DA control module, a storage circuit module, a communication module and a power module; The control module is connected to the AD acquisition module to collect the tension and pressure sensor data of the testing machine; The control module is connected to the DA control module and outputs control signals of the hydraulic servo valve and the DC servo motor; The control module is connected to the storage circuit module and is used to store log files and sensor parameters; The control module is connected to the communication module for communicating with the host computer or the remote handheld terminal; The power supply module is used to supply power to each module.

2. The ARM-based electromagnetic resonance high-frequency fatigue testing machine controller according to claim 1 is characterized in that: The AD acquisition module includes an analog switch circuit, an instrumentation amplifier, a Butterworth low-pass filter, a single-ended signal to differential signal circuit and an AD conversion chip; the analog signal output by the sensor first enters the instrumentation amplifier through the analog switch for voltage amplification, then is filtered through the Butterworth low-pass filter, and then is converted into a differential signal using the single-ended signal to differential signal circuit, then enters the AD conversion chip to be converted into a digital signal, and finally is transmitted to the control module through the SPI bus.

3. The ARM-based electromagnetic resonance high-frequency fatigue testing machine controller according to claim 1 is characterized in that: The DA conversion module is composed of a 16-bit precision DA conversion chip and peripheral circuits. The digital signal sent by the control module is converted into an analog signal by the DA conversion chip and is used to control the servo DC motor to realize the static control function of the high-frequency fatigue testing machine.

4. The ARM-based electromagnetic resonance high-frequency fatigue testing machine controller according to claim 1 is characterized in that: The communication module includes a USB communication module, a serial port module and an Ethernet module; The USB communication module is used to connect to a USB flash drive to achieve firmware upgrade; The serial port module includes two interfaces, RS232 and RS485; the RS232 interface is used to realize the debugging function; the RS485 interface is used to communicate with the remote handheld terminal; The Ethernet module is used to connect to the host computer.

5. The ARM-based electromagnetic resonance high-frequency fatigue testing machine controller according to claim 1 is characterized in that: The storage circuit module includes an EEPROM.

6. The ARM-based electromagnetic resonance high-frequency fatigue testing machine controller according to claim 1 is characterized in that: The power supply module includes a DCDC circuit and an LDO circuit. The DCDC circuit is used to convert the input 220V AC power into a 24V DC power supply; the LDO circuit is used to provide differential and stable power supply to each module.

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