Electro-hydraulic servo closed-loop controller of material testing machine

Abstract

The utility model discloses an electro-hydraulic servo closed-loop controller of a material testing machine, which belongs to the technical field of closed-loop control systems of material testing machines, and comprises a controller shell, one side of the controller shell is provided with a controller cooling fan, a controller power output X19, a synchronous input end output port and an expansion interface, the controller cooling fan is connected with the controller power switch through the back plate, the controller cooling fan is connected with the high-precision linear power supply through the controller power switch, and the core control panel is arranged in the controller shell. Therefore, errors generated by transmission between the hydraulic station and the oil cylinder in the whole transmission process can be eliminated, and high static positioning accuracy is ensured.

Description

Technical Field

[0001] The utility model belongs to the technical field of closed-loop control systems of material testing machines, and in particular relates to an electro-hydraulic servo closed-loop controller of a material testing machine. Background Art

[0002] Since the last century, CNC systems have been rapidly developing, striving for high performance, high precision, openness, intelligence, and high stability. These high performance and high precision are primarily achieved through motion controllers and actuators. Early control systems were based on single-chip microcomputers (MCUs), implementing functions such as position detection and signal feedback processing. However, due to the slow execution speed of MCUs, the control cycle of CNC systems was relatively long, significantly limiting control accuracy and ensuring real-time control and stable, high-performance control. MCU controllers, with their powerful computing power, significantly shortened control cycles, fast processing speed, and excellent real-time control performance, effectively address these issues. In the practical application of MCU CNC systems, optimizing their performance and ensuring control system stability requires selecting an appropriate control strategy. PID control is simple, effective, easy to implement, widely applicable, and highly robust. Consequently, PID control has become a well-established control strategy, particularly when the controlled object's configuration is uncertain or modeling is difficult. The traditional PID control method can no longer meet the high-speed, high-performance and system stability requirements of the control system with DSP as the core processor. Therefore, a full-closed-loop control solution of incremental digital PID control is adopted to better exert the performance of the system and make it run more stably. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the problems raised in the background technology.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0005] An electro-hydraulic servo closed-loop controller for a material testing machine includes a controller housing, a controller cooling fan, and a controller power switch. One side of the controller housing is provided with the controller cooling fan, controller power output X19, a synchronization input output port, and an expansion interface. The controller cooling fan is connected to the controller power switch via a backplane, and the controller cooling fan is connected to a high-precision linear power supply via the controller power switch. A core control board is provided inside the controller housing. The high-precision linear power supply controls the controller cooling fan via a switch button. The high-precision linear power supply is electrically connected to the controller power output X19 and the 24V linear power supply output, and the high-precision linear power supply is electrically connected to the synchronization input.

[0006] The other side of the controller housing 18 is provided with a drive interface X45, a test port 6, an expansion port Y17, a communication X16 interface 8, a remote control port X59, a displacement X7 interface 10, an action controller X211, a servo valve output interface X1812, a deformation input X14-1 interface 13, a load input X14 interface 14, a controller power input interface 15, a controller power switch 16 and a ground terminal 17.

[0007] The synchronous input and output port 3, expansion interface 4, drive interface X4 5, test port 6 and expansion port Y17, communication X16 interface 8, remote control port X5 9, displacement X7 interface 10, motion controller X2 11, servo valve output interface X18 12, deformation input X14-1 interface 13, and load input X14 interface 14 are all electrically connected to the core control board, and the controller power input interface 15 is electrically connected to the controller power switch 16.

[0008] Compared with the prior art, the present invention has the following beneficial effects:

[0009] It is suitable for loading control with dynamic high acquisition frequency requirements, and can realize static and dynamic test control. The test control frequency is 10HZ, and the test sensor acquisition frequency is 1000HZ. The displacement sensor, bridge pressure sensor and bridge deformation sensor detection elements perform position detection, pressure detection and deformation detection on the controlled unit to obtain more accurate position control and force control, thereby eliminating the error caused by the transmission during the entire transmission process between the hydraulic station and the cylinder, ensuring high static positioning accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a front structural schematic diagram of an embodiment of the utility model.

[0011] Figure 2 It is a schematic diagram of the back structure of an embodiment of the present utility model.

[0012] Figure 3 It is a schematic diagram of the STM32F429VGT6 MCU of an embodiment of the present utility model.

[0013] Figure 4 This is a schematic diagram of the input and output IO part of the core board of an embodiment of the utility model.

[0014] Figure 5 This is a schematic diagram of the power supply portion of the core board of an embodiment of the present utility model.

[0015] Figure 6 This is a partial schematic diagram of the force, deformation and displacement circuits of an embodiment of the utility model.

[0016] Figure 7 It is a partial schematic diagram of the AD7779 circuit of an embodiment of the present utility model.

[0017] Figure 8 This is a servo valve drive circuit diagram of an embodiment of the utility model.

[0018] Serial number and name of the accompanying drawings: Controller cooling fan 1, controller power output X19 2, synchronization input output port 3, expansion interface 4, drive interface X4 5, test port 6, expansion port Y1 7, communication X16 interface 8, remote control port X59, displacement X7 interface 10, motion controller X2 11, servo valve output interface X18 12, deformation input X14-1 interface 13, load input X14 interface 14, controller power input interface 15, controller power switch 16, grounding terminal 17, controller housing 18. DETAILED DESCRIPTION

[0019] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The exemplary embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0020] In the description of the present invention, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "top", "bottom", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention. Example

[0021] like Figure 1-8As shown, the electro-hydraulic servo closed-loop controller of a material testing machine described in the present invention includes a controller housing 18, a controller cooling fan 1 and a controller power switch 16. One side of the controller housing 18 is provided with the controller cooling fan 1, the controller power output X19 2, the synchronization input output port 3 and the expansion interface 4. The controller cooling fan 1 is connected to the controller power switch 16 through the backplane, and the controller cooling fan 1 is connected to the high-precision linear power supply through the controller power switch 16. A core control board is provided inside the controller housing 18. The high-precision linear power supply controls the controller cooling fan 1 through a switch button. The high-precision linear power supply is electrically connected to the controller power output X192 and the 24V linear power output end, and the high-precision linear power supply is electrically connected to the synchronization input end; the other side of the controller housing 18 is provided with a drive interface X45, a test port 6, an expansion port Y1 7, a communication X16 interface 8, a remote control port X5 9, a displacement X7 interface 10, an action controller X2 11, and a servo valve output interface X18 12, deformation input X14-1 interface 13, load input X14 interface 14, controller power input interface 15, controller power switch 16 and ground terminal 17; synchronization input output port 3, expansion interface 4, drive interface X45, test port 6 and expansion port Y17, communication X16 interface 8, remote control port X59, displacement X7 interface 10, motion controller X211, servo valve output interface X1812, deformation input X14-1 interface 13, load input X14 interface 14 are all electrically connected to the core control board, and the controller power input interface 15 is electrically connected to the controller power switch 16.

[0022] The controller cooling fan is connected to a high-precision linear power supply through the power switch. The power output port X19 is connected to a high-precision linear switching power supply to provide a 24V DC switching power supply output. The synchronous input and output port is connected to the core control board to synchronize the input and output of control signals when multiple controllers are used. The expansion interface is connected to the core control board to sample the sampling channels of multiple sensors. The drive interface X4 is connected to the core control board and is the IO level signal input and output port of the controller, used to control the remote switch control signal; the test port is connected to the core control board and is used to monitor and modify the program during debugging; the expansion port Y1 is connected to the core control board and is used as a reserved interface for adding functions or sensors later; the communication interface X16 is connected to the core control board and serves as the communication interface between this controller and the computer Ethernet; the remote control port X5 is connected to the core control board and is reserved for the communication interface of the remote hand control box; the displacement interface X7 is connected to the core control board and serves as the input port of the displacement sensor in the controller; the actuator control X2 is connected to the core The core control board is connected for upper and lower limit control of the actuator; the central servo valve output interface X18 is connected to the core control board for controlling the voltage or current output signal of the servo valve; the deformation input X14-1 interface is connected to the core control board for signal input of the deformation sensor; the load input X14 interface is connected to the core control board for signal input of the load sensor; the controller power input is connected to the control switch of the controller to control the power supply of the entire controller; the controller power switch is connected to the high-precision linear power supply to control the power on and off of the entire controller; the grounding terminal is connected to the controller casing to ensure that the controller has good grounding; controller casing.

[0023] The purpose of this utility model is to provide a single-channel electro-hydraulic servo controller and software control system. The system can realize the control of a single-channel dynamic hydraulic cylinder. The controller uses the ARM architecture STM32F429VGT6 and the external A / D chip AD7779 and D / A conversion chip LTC1668 to establish a digital PID controller. Due to the extremely fast running speed and strong computing data processing capability of the STM32F429VGT6, it can more effectively enable the control system to operate stably and in real time according to the task requirements. The controller is designed with "PC + The development-type CNC system in the MCU motion controller mode adopts full closed-loop control. It consists of 1 controller cooling fan, which is connected to the power switch 16 through the backplane, and is connected to the high-precision linear power supply through the power switch. The high-precision linear power supply controls the cooling fan through the switch button; 2 controller power output X19, 24V linear power output, is connected to the high-precision linear power supply, and reserves the 24V power signal of the servo or other sensors for the control equipment; 3 synchronization input, connected to the 51 pin of the CPU chip STM32F429VGT6, to ensure the clock consistency of the two controllers. When multiple controllers are synchronized, the clocks of each controller need to be synchronized. Clock and control signals, need to connect synchronization signals; 4 reserved interface board interface, used for AD input interface reserved terminals for other sensors, connect AD7779 AI3 to AI7 pins; 5 drive interface X4, controller IO level signal input and output port, used to control remote switch control signal, connected to ULN2803LW, this chip is controlled by CPU chip STM32F429VGT6; 6 test interface Tx, directly connected to the controller CPU chip STM32F429VGT6, used for PC host computer debugging and refreshing firmware program; 7 expansion interface Y1, and as a reserved interface reserved for later adding functions or sensor functions; 8 Communication interface X16, directly connected to the controller's CPU chip STM32F429VGT6, used for Ethernet communication with the host computer, can be directly connected to the host PC for communication or, when using multiple controllers, use a switch to communicate with the sample PC for control; 9 Remote control X5, directly connected to the controller's CPU chip STM32F429VGT6, reserved for the communication interface of the remote manual control box; 10 Displacement X7 interface, in the SSI sensor, directly connected to the SPI interface of the controller's CPU chip STM32F429VGT6. In the testing machine, the interface of the displacement sensor is used. The controller has a DB25-core connector, which supports SSI displacement sensors, LVDTs and other analog displacement sensors, and incremental displacement sensors. 11 Actuator control X2, connected to the I / O signal, and then connected to the controller's CPU chip STM32F429VGT6, for upper and lower limit control of the actuator;12 Servo valve output X18, connected to the servo valve drive circuit, can be connected to all domestic servo valves controlled by current signals and servo valves controlled by voltage such as MOOG and ATOS; 13 Deformation input X14-1, connected to the deformation circuit, collected through AD7779, connected to the CPU chip STM32F429VGT6, to collect strain bridge deformation sensor; 14 Load input X14 , connected to the force circuit, collected through the AD7779, connected to the CPU chip STM32F429VGT6, and collected the strain load sensor as the load input of the material testing machine; 15AC220V power input interface, connected to the controller 220V power supply, connected to the power switch 16, used to control the power supply of the entire controller; 16 controller power switch, connected to the 15AC220V power supply and high-precision linear power supply, used to control the power on and off of the entire controller; 17 ground terminal, connected to the controller housing; 18 controller housing and the control circuit board inside the controller. The controller uses displacement sensors, bridge pressure sensors, and bridge deformation sensors to detect the position, pressure, and deformation of the controlled unit, achieving more accurate position and force control, thereby eliminating the transmission error generated by the entire transmission process between the hydraulic station and the cylinder, ensuring high static positioning accuracy. From these points of view, it is difficult for open-loop control to meet the control requirements of the system. In a closed-loop control system, the main control is to reduce the deviation between the controlled quantity and the set value. The deviation is caused by various actual disturbances. The fully closed-loop control system is not only able to effectively resist some actual disturbances, but also is not particularly sensitive to the fluctuations of the system's own component parameters.

[0024] Bridge pressure sensor, through 3 interface X14 and Figure 8 The force circuit connection of the controller, the low-pass filter circuit and the sensor power supply processing send the processed voltage signal to the AI1+ and AI1- ports of the AD7779 chip, and are collected by the main control chip STM32F429VGT6.

[0025] The bridge-type deformation sensor is connected to the deformation circuit of the controller through the 14-port X14-1, the low-pass filter circuit and the sensor power supply processing, and the processed voltage signal is sent to the AI2+ and AI2- ports of the AD7779 chip, which is then collected by the main control chip STM32F429VGT6.

[0026] The LVDT displacement sensor is connected to the displacement circuit of the controller through the 10 interface X7. The low-pass filter circuit and sensor power supply processing send the processed voltage signal to the AI3+ and AI3- ports of the AD7779 chip, which is then collected by the main control chip STM32F429VGT6.

[0027] The servo hydraulic valve is connected to the servo valve drive circuit through the 12 interface. The servo valve power supply circuit and drive circuit are controlled by the main control chip STM32F429VGT6 through PID comparison and calculation, and the control signal is input into the DA chip DAC 1220 chip, and then output to the servo valve through the servo valve drive circuit to control the movement of the cylinder.

[0028] The absolute encoder sensor is directly connected to the main control chip STM32F429VGT6 through a 10-port DB25-pin connector with different pin numbers. The main control chip collects the encoder's pulse signal through interrupts.

[0029] For controllers, hardware is the foundation and software is the soul. Software has become the main body of computer automatic control systems and largely determines the system's advancement, reliability, practicality, and real-time performance. The control system can achieve precise control of the piston through three closed-loop automatic control using absolute position encoder sensors, pressure sensors, and workpiece deformation sensors. In the early stages of the test, displacement closed-loop control is used to accurately control the displacement of the hydraulic cylinder piston until the workpiece is clamped. Subsequently, the system switches to force closed-loop control mode, accurately applying pressure to the test workpiece until the workpiece reaches the force limit and deforms. At this point, the force closed-loop control is converted to deformation closed-loop control, allowing the workpiece to deform smoothly. When the workpiece reaches its deformation limit, i.e., yield deformation, the system quickly switches back to displacement control mode to avoid impact on the workpiece due to the inertia of the hydraulic piston after yielding, thereby achieving a smooth and safe test. The entire process of the test specimen being deformed by external force is fully recorded throughout the experiment, and a test report is generated.

[0030] The control system can realize closed-loop control of the displacement of the testing machine through the displacement sensor. The displacement sensor can be selected from position encoding sensor, SSI signal displacement sensor and analog displacement sensor.

[0031] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only intended to help understand the principles of the embodiments of the present invention.

Claims

1. An electro-hydraulic servo closed-loop controller for a material testing machine, comprising a controller housing (18), a controller cooling fan (1) and a controller power switch (16), characterized in that: A controller cooling fan (1), a controller power output X19 (2), a synchronization input output port (3) and an expansion interface (4) are provided on one side of the controller housing (18); the controller cooling fan (1) is connected to the controller power switch (16) via a back panel; the controller cooling fan (1) is connected to a high-precision linear power supply via the controller power switch (16); a core control board is provided inside the controller housing (18); the high-precision linear power supply controls the controller cooling fan (1) via a switch button; the high-precision linear power supply is electrically connected to the controller power output X19 (2) and the 24V linear power output; and the high-precision linear power supply is electrically connected to the synchronization input.

2. The electro-hydraulic servo closed-loop controller for a material testing machine according to claim 1, characterized in that: The other side of the controller housing (18) is provided with a drive interface X4 (5), a test port (6), an expansion port Y1 (7), a communication X16 interface (8), a remote control port X5 (9), a displacement X7 interface (10), an action controller X2 (11), a servo valve output interface X18 (12), a deformation input X14-1 interface (13), a load input X14 interface (14), a controller power input interface (15), a controller power switch (16) and a grounding terminal (17).

3. The electro-hydraulic servo closed-loop controller for a material testing machine according to claim 2, characterized in that: The synchronous input and output ports (3), the expansion interface (4), the drive interface X4 (5), the test port (6), the expansion port Y1 (7), the communication X16 interface (8), the remote control port X5 (9), the displacement X7 interface (10), the motion controller X2 (11), the servo valve output interface X18 (12), the deformation input X14-1 interface (13), and the load input X14 interface (14) are all electrically connected to the core control board, and the controller power input interface (15) is electrically connected to the controller power switch (16).

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