Displacement load hydraulic loading test system based on PID (Proportion Integration Differentiation) control

Abstract

The invention discloses a displacement load hydraulic loading test system based on PID control. The displacement load hydraulic loading test system is composed of an actuator, a hydraulic station and a control system. The actuator is composed of a cylinder body, a valve block, a servo valve, a displacement sensor and a load sensor. The control system comprises a multi-channel data sampling module, a signal output module, a communication module, a PID control module and a man-machine interaction module, and the multi-channel data sampling module collects stress and displacement data information of the cylinder body through a displacement sensor and a load sensor, packages the data through the communication module and sends the data to the PID control module. The PID control module receives a control command through the man-machine interaction module, displays waveform data, dynamically outputs a current signal through the signal output module according to a data calculation result, and controls an opening of a servo valve to control an actuating cylinder to move according to a curve of the command. Displacement and stress data of the hydraulic cylinder can be checked in real time, and the cylinder body is controlled to move according to the input load spectrum.

Description

Technical Field

[0001] The present invention belongs to the field of hydraulic control, and specifically relates to a hydraulic cylinder pressure and position control system for a displacement-load hydraulic loading test system based on PID control, which is applicable to scenarios such as material mechanics performance testing, bridge structure health monitoring, and aerospace component verification. Background Art

[0002] The displacement-load hydraulic loading test procedure is a core technology in the field of engineering tests and is widely used in scenarios such as material mechanics performance testing, bridge structure health monitoring, and aerospace component verification. Its core goal is to precisely control displacement or load through a hydraulic system to simulate the mechanical behavior under actual working conditions. Currently, the core components of the displacement-load hydraulic loading test rely on imports, and high-frequency response servo valves, high-precision force sensors, etc. are still mainly of European and American brands (such as Moog, HBM). The software platform is weak, lacking a general development environment similar to LabVIEW, and the threshold for secondary development is high. The standard system is imperfect, the domestic test procedures have poor compatibility, and it is difficult to meet the requirements of international multi-standard tests. The future development trend will be intelligent upgrade, AI real-time optimization of control parameters, reduction of manual intervention, and the use of digital twin to achieve closed-loop verification of "virtual test - physical loading". Nanoscale displacement control based on FPGA (such as semiconductor material testing). The adoption of electro-hydraulic hybrid drive technology (such as Festo Motion Terminal). With policy support, domestic high-precision sensors and controllers have gradually made breakthroughs (such as Huawei HiSilicon chips enabling edge computing), and the acceleration of domestic substitution has been gradually realized. Through universities focusing on core algorithms (such as adaptive control) and enterprises promoting engineering implementation, the collaboration between industry, academia, and research is achieved; the development of an open-source test program framework (similar to ROS for Robotics) to reduce development costs. Promote the mutual recognition of domestic standards and ISO / IEC to enhance the international competitiveness of domestic equipment. Through technology catch-up and innovation, it is expected that a domestically controllable industrial chain for the displacement-load hydraulic loading test procedure will be formed in China. Summary of the Invention

[0003] The purpose of the present invention is to propose a displacement-load hydraulic loading test system based on PID control in view of the deficiencies of the domestic displacement-load hydraulic loading test procedure.

[0004] The present invention proposes a displacement-load hydraulic loading test system based on PID control, which is composed of three parts: an actuator, a hydraulic station, and a control system;

[0005] The actuator is composed of a cylinder block, a valve block, a servo valve, a displacement sensor, and a load sensor.

[0006] The control system includes a multi-channel data sampling module, a signal output module, a communication module, a PID control module, and a human-machine interaction module.

[0007] The output end of the multi-channel data sampling module is unidirectionally signal-connected to the input end of the communication module; the signal end of the communication module is bidirectionally connected to the signal end of the PID control module; the signal end of the communication module is bidirectionally connected to the signal end of the human-computer interaction module; the output end of the PID control module is unidirectionally signal-connected to the input end of the signal output module;

[0008] The multi-channel data sampling module collects voltage values of different channels through the displacement sensor and the load sensor to obtain displacement and stress information. The output end of the multi-channel data sampling module is unidirectionally signal-connected to the input end of the communication module, and the communication module uses a queue to pack and transmit the data to the communication module.

[0009] The communication module transmits the stress and displacement data obtained by the multi-channel data sampling module and the control commands of the human-computer interaction module to the PID control module through the queue method.

[0010] The output end of the PID control module is unidirectionally signal-connected to the input end of the signal output module; the PID control module inputs a control signal to the signal output module, and the signal output module generates a corresponding control current to control the movement of the cylinder block.

[0011] Preferably, the communication module completes the real-time and stable transmission of data by packing the input data and sending it to the queue.

[0012] Preferably, the multi-channel data sampling module samples the stress and displacement parameters of the cylinder block in real time and can set the sampling frequency to achieve high-frequency sampling. Then the sampled data is uploaded to the communication module.

[0013] Preferably, the control cabinet implemented by the control system includes an embedded lower computer CompactRIO controller, a signal acquisition module NI-9252, a signal output module NI-9265, signal isolation conditioning modules ADAM-3016 and ADAM-3014, and a MACX MCR-UI-UI-NC isolation amplifier.

[0014] Preferably, the fuzzy PID algorithm adopted by the PID control module processes and judges according to the input data of the communication module and makes real-time feedback adjustment to the PLC control, which is specifically as follows:

[0015] S1: Receive once after collecting each sine waveform data, subtract the received sampled data from the expected value to obtain the error value e(k) of each parameter at time k;

[0016] S2: Obtain a set of input quantities x1(k), x2(k), x3(k) according to the error value e(k) at time k, and calculate the error values at times k-1 and k-2; where,

[0017] x1(k) = e(k); x2(k) = e(k) - e(k - 1);

[0018] x3(k) = e(k) - 2e(k - 1) + e(k - 2);

[0019] Δu(k) = x1(k) + x2(k) + x3(k);

[0020] S3: Take Δu(k) as the input to obtain the error e and the error change rate e c ; Use the following formula to linearly map Δu(k) in the interval [a, b] to the fuzzy domain [c, d] to obtain the fuzzy variables E and E c ;

[0021]

[0022] S4: Select the normal function as the membership function, divide the fuzzy domain into 7 intervals, corresponding to 7 fuzzy subsets: negative big NB, negative medium NM, negative small NS, zero ZE or ZO, positive small PS, positive medium PM, positive big PB; Obtain E and E according to experience c For K in different intervals p 、K i 、K d The fuzzy rule table, and obtain the fuzzy relationship through the fuzzy inference method, and respectively obtain the values of K p 、K i 、K d ;

[0023] S5: According to K p 、K i 、K d , after defuzzification, obtain the output control quantity u(k); Input u(k) into the corresponding model function to obtain the output y(k);

[0024] S6: Input the output y(k) into the signal output module to generate the corresponding control current to control the movement of the cylinder block, realize the load spectrum control of the stress or displacement of the cylinder block, and realize the stability of the system.

[0025] The beneficial effects of the present invention are as follows:

[0026] Between the multi-channel data sampling module and the PID control module of the present invention, the sampling data is transmitted in the form of a FIFO queue, which can reduce the burden on the CPU, improve the data transmission speed, and realize the real-time control of the PID.

[0027] The present invention adopts an embedded lower computer CompactRIO controller, a signal acquisition module NI-9252, and a signal output module NI-9265, which can realize high-frequency sampling and real-time processing of signals, and the corresponding speed is very fast.

[0028] The present invention adopts multi-sensor data fusion technology, fuzzy PID control technology, etc., which can obtain the stress parameters and displacement parameters of the hydraulic cylinder body in real time. The system has good robustness, can quickly and accurately complete the action requirements of the load spectrum, and ensures the accuracy and stability of the test process. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the basic structure of a displacement load hydraulic loading test system with PID control according to the present invention.

[0030] Figure 2 It is a flowchart of the fuzzy PID control algorithm according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] A displacement load hydraulic loading test system with PID control according to the present invention, its detailed implementation includes the following details:

[0032] As Figure 1 shown, a displacement load hydraulic loading test system with PID control includes a multi-channel data sampling module, a signal output module, a communication module, a PID control module, and a human-machine interaction module.

[0033] The multi-channel data sampling module is connected to the displacement sensor and the stress sensor. The displacement sensor is a magnetostrictive displacement sensor, which is installed on the hydraulic cylinder body to measure the displacement value of the position where the hydraulic cylinder is located. The stress sensor adopts a spoke-type pressure sensor, which is installed at the top of the hydraulic cylinder to measure the stress data borne by the hydraulic cylinder during operation.

[0034] The communication module transmits the displacement and stress sensor data information collected by the data sampling module to the PID control module and the human-machine interaction module. Similarly, the communication module also sends the control commands of the human-machine interaction module to the PID control module.

[0035] The real-time data information of the hydraulic cylinder is sampled and transmitted through the FIFO queue of the communication module. It has the advantages of low power consumption cost, small burden on the CPU, preventing data loss, and fast data transmission speed, which just meets the requirements of the displacement load hydraulic loading test system for response speed and data accuracy.

[0036] The PID control module receives the control commands transmitted by the human-machine interaction module, and calculates and processes the hydraulic cylinder displacement and stress data information of the data sampling module. Finally, the calculation result is output through the signal output module to control the hydraulic valve to achieve precise control of the hydraulic cylinder.

[0037] The human - machine interaction module receives the displacement and stress sensor data information collected by the sampling module through the communication module and visualizes the data, which is displayed in the form of a chart curve.

[0038] As Figure 2 shown, the PID control module adopts the fuzzy PID control algorithm. Taking the displacement and stress sensor data information collected by the sampling module as input, it performs feedback regulation through processing and calculation. The specific steps are as follows:

[0039] S1: Receive once after each sine - wave data is collected. Subtract the received sampling data from the expected value (load - spectrum input) to obtain the error value e(k) of each parameter at time k.

[0040] S2: Obtain a set of input quantities x1(k), x2(k), x3(k) based on the error value e(k) at time k, and calculate the error values at times k - 1 and k - 2. Among them,

[0041] x1(k)=e(k); x2(k)=e(k)-e(k - 1);

[0042] x3(k)=e(k)-2e(k - 1)+e(k - 2);

[0043] Δu(k)=x1(k)+x2(k)+x3(k);

[0044] S3: Take Δu(k) as the input to obtain the error e and the error change rate e c ; Use the following formula to linearly map Δu(k) in the interval [a, b] to the fuzzy domain [c, d] to obtain the fuzzy variables E and E c ;

[0045]

[0046] S4: Select the normal function as the membership - degree function. Divide the fuzzy domain into 7 intervals, which respectively correspond to 7 fuzzy subsets: negative big NB, negative medium NM, negative small NS, zero ZE or ZO, positive small PS, positive medium PM, and positive big PB. According to experience, obtain the fuzzy - rule tables of E and E c in different intervals for K p 、K i 、K d and obtain the fuzzy relationship through the fuzzy - inference method, and respectively obtain the values of K p 、K i 、K d ;

[0047] S5: According to K p 、K i 、Kd , the output control quantity u(k) is obtained after defuzzification;

[0048]

[0049] The output y(k) is obtained by inputting u(k) into the corresponding model function;

[0050] S6: By inputting the output y(k) into the signal output module to generate a corresponding control current to control the movement of the cylinder block, the load spectrum control of the stress or displacement of the cylinder block is realized, and the stability of the system is achieved.

[0051] The present invention proposes a displacement load hydraulic loading test system based on PID control, which can accurately and quickly complete the displacement load hydraulic loading test task and contributes to making up for the deficiencies of the domestic displacement load hydraulic loading test procedure.

Claims

1. A displacement load hydraulic loading test system based on PID control, characterized in that, The system consists of three parts: an actuator, a hydraulic station, and a control system; The actuator consists of a cylinder block, a valve block, a servo valve, a displacement sensor, and a load sensor. The control system includes a multi-channel data sampling module, a signal output module, a communication module, a PID control module, and a human-machine interaction module. The output end of the multi-channel data sampling module is unidirectionally signal-connected to the input end of the communication module; the signal end of the communication module is bidirectionally connected to the signal end of the PID control module; the signal end of the communication module is bidirectionally connected to the signal end of the human-machine interaction module; the output end of the PID control module is unidirectionally signal-connected to the input end of the signal output module; The multi-channel data sampling module collects voltage values of different channels through the displacement sensor and the load sensor to obtain displacement and stress information. The output end of the multi-channel data sampling module is unidirectionally signal-connected to the input end of the communication module, and the communication module uses a queue to pack and transmit the data to the communication module. The communication module transmits the stress and displacement data obtained by the multi-channel data sampling module and the control commands of the human-machine interaction module to the PID control module through a queue. The output end of the PID control module is unidirectionally signal-connected to the input end of the signal output module; the PID control module inputs a control signal to the signal output module, and the signal output module generates a corresponding control current to control the movement of the cylinder block.

2. The displacement load hydraulic loading test system based on PID control according to claim 1, characterized in that, The multi-channel data sampling module samples the stress and displacement parameters of the cylinder block in real time and can set the sampling frequency to achieve high-frequency sampling. Then the sampled data is uploaded to the communication module.

3. The displacement load hydraulic loading test system based on PID control according to claim 1, characterized in that The communication module completes the real-time and stable transmission of data by packing the input data and sending it to the queue.

4. The displacement load hydraulic loading test system based on PID control according to claim 1, characterized in that The control cabinet implemented by the control system includes an embedded lower computer CompactRIO controller, a signal acquisition module NI-9252, a signal output module NI-9265, signal isolation conditioning modules ADAM-3016 and ADAM-3014, and a MACX MCR-UI-UI-NC isolation amplifier.

5. The displacement load hydraulic loading test system based on PID control according to claim 1, characterized in that, The fuzzy PID algorithm adopted by the PID control module processes and judges according to the input data of the communication module and makes real-time feedback adjustment to the PLC control, which is specifically as follows: S1: Receive once after each sine wave data is collected, subtract the received sampled data from the expected value to obtain the error value e(k) of each parameter at time k; S2: Obtain a set of input quantities x1(k), x2(k), x3(k) according to the error value e(k) at time k, and calculate the error values at times k-1 and k-2; where, x1(k) = e(k); x2(k) = e(k) - e(k-1); x3(k) = e(k) - 2e(k-1) + e(k-2); Δu(k) = x1(k) + x2(k) + x3(k); S3: Take Δu(k) as the input to obtain the error e and the error change rate e c ; linearly map Δu(k) in the interval [a, b] to the fuzzy domain [c, d] using the following formula to obtain the fuzzy variables E and E c ; S4: Select the normal function as the membership function, and divide the fuzzy domain into 7 intervals, corresponding to 7 fuzzy subsets: negative big (NB), negative medium (NM), negative small (NS), zero (ZE or ZO), positive small (PS), positive medium (PM), and positive big (PB); obtain the fuzzy rule tables of E and E c on different intervals for K p , K i , K d , and obtain the fuzzy relationship through the fuzzy inference method, and separately calculate the values of K p , K i , K d ; S5: According to K p , K i , K d , after defuzzification, the output control quantity u(k) is obtained; u(k) is input into the corresponding model function to obtain the output y(k); S6: Input the output y(k) into the signal output module to generate a corresponding control current to control the movement of the cylinder block, realize the load spectrum control of the stress or displacement of the cylinder block, and realize the stability of the system.

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