scholarly journals VIBRATIONAL CASE STUDY FOR THE MOLD OSCILLATOR WITH HYDRAULIC SERVO SYSTEM

2019 ◽  
Vol 25 (2) ◽  
Author(s):  
PARK YONGHUI ◽  
LEE CHANGWOO ◽  
KIM DONGWOOK
Keyword(s):  
Natural Frequency ◽  
Servo System ◽  
Hydraulic Cylinder ◽  
Design Parameters ◽  
Natural Mode ◽  
Hydraulic Servo ◽  
Hydraulic Servo System ◽  
Mold Oscillator ◽  
The One

<p>We have conducted sensitivity analysis to investigate the two-hydraulic-servo system for the mold oscillator. By modelling mathematical models for operating fluid flow to control a hydraulic cylinder, we changed design parameters and environment conditions including friction, additional spring stiffness and fluid leakage. From the one-hydraulic servo system to the two-hydraulic cylinder, modal analysis was conducted to figure out dynamic characteristics of the real system. Especially, we categorized important natural mode shape. When the system was excited into the natural frequency, the 1st mechanical natural frequency could cause a pressure gain by reducing internal pressure of a hydraulic cylinder, but other natural frequencies were critically dangerous by generating imbalance, over-vibration and distortion. By comparing the results to the experimental data, we could find a dramatic pressure drop near 3 Hz oscillation when the system has the 1st mechanical natural frequency 2.499 Hz. Also, the system has the imbalance near 6 Hz oscillation when the system has 2nd mechanical natural frequency 5.446 Hz. Based on these fact, we have suggested some tips to oscillate a mold efficiently and safely.</p>

scholarly journals VIBRATIONAL CASE STUDY FOR THE MOLD OSCILLATOR WITH HYDRAULIC SERVO SYSTEM

2019 ◽  
Vol 25 (2) ◽  
pp. 33-47
Author(s):  
YONGHUI PARK ◽  
LEE CHANGWOO ◽  
KIM DONGWOOK
Keyword(s):  
Natural Frequency ◽  
Servo System ◽  
Hydraulic Cylinder ◽  
Design Parameters ◽  
Natural Mode ◽  
Hydraulic Servo ◽  
Hydraulic Servo System ◽  
Mold Oscillator ◽  
The One

We have conducted sensitivity analysis to investigate the two-hydraulic-servo system for the mold oscillator. By modelling mathematical models for operating fluid flow to control a hydraulic cylinder, we changed design parameters and environment conditions including friction, additional spring stiffness and fluid leakage. From the one-hydraulic servo system to the two-hydraulic cylinder, modal analysis was conducted to figure out dynamic characteristics of the real system. Especially, we categorized important natural mode shape. When the system was excited into the natural frequency, the 1st mechanical natural frequency could cause a pressure gain by reducing internal pressure of a hydraulic cylinder, but other natural frequencies were critically dangerous by generating imbalance, over-vibration and distortion. By comparing the results to the experimental data, we could find a dramatic pressure drop near 3 Hz oscillation when the system has the 1st mechanical natural frequency 2.499 Hz. Also, the system has the imbalance near 6 Hz oscillation when the system has 2nd mechanical natural frequency 5.446 Hz. Based on these fact, we have suggested some tips to oscillate a mold efficiently and safely.

The Modeling and Control of the Hydraulic Servo System by Using On-Off Valve

2000 ◽  
Author(s):  
Xuanyin Wang
Keyword(s):  
Servo System ◽  
Mathematic Model ◽  
Hydraulic Cylinder ◽  
Servo Control ◽  
Linear Quadratic ◽  
Modeling And Control ◽  
Hydraulic Servo ◽  
Self Tuning ◽  
Hydraulic Servo System ◽  
And Control

Abstract This paper researches on the hydraulic servo system by using ordinary on-off valves. The mathematic model of an asymmetric hydraulic cylinder servo control system is built, and its characteristic is analysed here. To reduce the static and dynamic characteristic differences between forward and reverse motion of asymmetric cylinder, and improve system’s performance, a self-tuning linear quadratic gaussian optimum controller (SLQG) is designed successful. In the end, an asymmetric hydraulic cylinder servo system of paint robot is researched. The result shows that the above method is effective.

Design and Integrated Simulation of the Electro-Hydraulic Servo System Based on AMESim and Matlab

2010 ◽  
Vol 44-47 ◽  
pp. 1355-1359 ◽  
Author(s):  
Xiang Xu ◽  
Zhi Xiong Li ◽  
Hong Ling Qin
Keyword(s):  
Control System ◽  
Design Method ◽  
Design Procedure ◽  
Servo System ◽  
Hydraulic Cylinder ◽  
Fast Response ◽  
Simulation Design ◽  
Integrated Simulation ◽  
Hydraulic Servo ◽  
Hydraulic Servo System

Since electro-hydraulic servo system has fast response and highest control accuracy, it has been widely used in industrial application, including aircraft, mining, manufacturing, and agriculture, etc. With the fast development of computer science, it is feasible and available to evaluate the performance of the designed control system via virtual simulation before the practical usage of the system. In order to optimize the design procedure of the electro-hydraulic proportional controller, the co-simulation design method based on AMESim-Matlab is presented for the electro-hydraulic servo system in this paper. High accuracy of the mathematical model of electro-hydraulic servo system was full-fitted by the use of AMESim, and the advantage of high solving precision for large amount of calculation was full played using Matlab. The PID controller was employed to realize the efficient control of the motion of the hydraulic cylinder. The united simulation technique was adopted to verify the good performance of the designed control system. The simulation results suggest that the proposed method is effective for the design of electro-hydraulic servo systems and thus has application importance.

Suppression of Micro Stick-Slip Vibrations in Hydraulic Servo-System

1998 ◽  
Vol 122 (2) ◽  
pp. 249-256 ◽  
Author(s):  
Toshiyuki Hayase ◽  
Satoru Hayashi ◽  
Kazunori Kojima ◽  
Ikuro Iimura
Keyword(s):  
Feedback Linearization ◽  
Servo System ◽  
Hydraulic Cylinder ◽  
Feedback Gain ◽  
Stick Slip ◽  
Servo Valve ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Hydraulic Servo ◽  
Hydraulic Servo System

This paper deals with suppression of two kinds of micro stick-slip vibrations occurring in a typical computer-controlled hydraulic servo-system. The relevant system consists of a single-rod hydraulic cylinder, an electrohydraulic servo-valve and a personal computer. The discontinuous control signal from a D/A converter causes a stick-slip vibration of micron order of magnitude over a wide range of the feedback gain. Increasing the feedback gain results in the other stick-slip vibration of nearly ten times larger amplitude due to the nonlinear pressure-flow characteristic of the servo-valve. The numerical simulation revealed the latter micro stick-slip vibration could be efficiently suppressed with the feedback linearization technique to compensate the nonlinearity of the servo-valve, while the former one reduced by improving the resolution of the D/A converter. Validities of both the methods were also confirmed with experiment. [S0022-0434(00)00102-7]

scholarly journals Research on the position–pressure cooperative control strategy for full-hydraulic leveler

2018 ◽  
Vol 10 (12) ◽  
pp. 168781401881739
Author(s):  
Dongping He ◽  
Tao Wang ◽  
Jun Wang ◽  
Zhongkai Ren ◽  
Xiangyu Gao
Keyword(s):  
Control Strategy ◽  
Cooperative Control ◽  
High Speed ◽  
Servo System ◽  
Hydraulic Cylinder ◽  
Relief Valve ◽  
Working Pressure ◽  
Pressure Signal ◽  
Hydraulic Servo ◽  
Hydraulic Servo System

The characteristics of electro-hydraulic servo system of full-hydraulic leveler are high speed, large inertia, high frequency response, and multi-degree of freedom. In order to improve the degree of automation of full-hydraulic leveler and achieve the simultaneous control between position and pressure, the position–pressure cooperative control strategy is presented in the article. In the working process, the dynamic working pressure signal of the hydraulic cylinder is turned into a real-time position signal by the pressure–position conversion gain and then compensates the converted signal into the position closed loop. Meanwhile, the pressure signal of the rear cavity of the hydraulic cylinder is fed back to the input of the proportional relief valve at the pump source, and then the system work pressure changes quickly according to the different thickness. In this article, the mathematical model of position–pressure cooperative control of hydraulic straightening machine is established. The simulation results in AMESim software verify the correctness of the control strategy. Finally, the feasibility and practicability of the control strategy are verified by the field prototype of 11-roller full-hydraulic leveler. The control strategy provides the theoretical basis for designing the electro-hydraulic servo system.

Design and Stimulation of Hydraulic Servo System for Vehicle Test Equipment for Rubber Shock Absorber

2010 ◽  
Vol 142 ◽  
pp. 243-247
Author(s):  
Cong Ling Zhu ◽  
Wei Zhu Jin ◽  
Wen Seng Gui
Keyword(s):  
Dynamic Characteristics ◽  
Shock Absorber ◽  
Servo System ◽  
Simulation Software ◽  
Test Equipment ◽  
Design Parameters ◽  
Core Element ◽  
Computer Emulation ◽  
Hydraulic Servo ◽  
Hydraulic Servo System

Development of special rubber shock absorber test equipment for vehicle will become very important, this equipment can test and analysis of dynamic characteristics for rubber shock absorber.The paper discusses the problem on optimum design of electro-hydraulic servo system which drives the vibration set. A closed system for controlling mechanical position or motion using feedback from the electro-hydraulic servo valve of the device as an input has been used in hydraulic servo system. The maximum region of design parameters has been defined for hydraulic servo cylinder as a core element of the electro-hydraulic exciting system. Established the mathematical model of the system, and the dynamic characteristics of the hydraulic servo cylinder are investigated by utilizing the simulation software MATLAB. The results of computer emulation show that this method is practical.

Design of an Experimental Platform for Hydraulic Servo System

2011 ◽  
Vol 69 ◽  
pp. 51-54
Author(s):  
Jin Fang Zhu
Keyword(s):  
Hydraulic System ◽  
Servo System ◽  
Hydraulic Cylinder ◽  
Hydraulic Motor ◽  
Electronic Components ◽  
Servo Systems ◽  
Experimental Platform ◽  
Overall Design ◽  
Hydraulic Servo ◽  
Hydraulic Servo System

VRLA (valve-regulated lead-acid) and Pump-control are the two kinds of power components for hydraulic servo system. With different command device, feedback measurement device and different corresponding electronic components, the hydraulic servo systems are different. To ensure maximum performance of the whole device, the overall design (including mechanical, electrical design) should be considered for hydraulic servo system. Machinery-electric-hydraulic should be in coordination with each other. The hydraulic system components are used to change the speed of hydraulic cylinder and alter direction of hydraulic cylinder and hydraulic motor. The solenoid valve for motor and hydraulic servo system and the control of pressure relay can implement by the electric section.

scholarly journals Characteristics of Position and Pressure Control of Separating Metering Electro-Hydraulic Servo System with Varying Supply Pressure for Rolling Shear

2020 ◽  
Vol 10 (2) ◽  
pp. 435
Author(s):  
Suhong Lin ◽  
Gaocheng An ◽  
Jiahai Huang ◽  
Jun Wang ◽  
Yuhang Guo
Keyword(s):  
Energy Savings ◽  
Servo System ◽  
Hydraulic Cylinder ◽  
Dynamic Surface Control ◽  
Tracking Accuracy ◽  
Rolling Shear ◽  
Dynamic Surface ◽  
Supply Pressure ◽  
Hydraulic Servo ◽  
Hydraulic Servo System

The traditional valve-controlled hydraulic servo system has large throttling losses and undergoes serious heat problems when used in electro-hydraulic servo systems (EHSSs) for a rolling shear. In order to improve the energy efficiency of the EHSS for the rolling shear while also ensuring the position tracking accuracy, the separate metering electro-hydraulic servo system with varying supply pressure (VSP-SMEHSS) is proposed in this work. The inlet valve controls the position of a hydraulic cylinder, while the outlet valve controls the back pressure of the hydraulic cylinder. However, due to the disturbance caused by the varying supply pressure, the proportional–integral–derivative (PID) controller or active disturbance rejection controller (ADRC) cannot meet the requirements of accuracy. In order to solve this problem, based on a nonlinear disturbance observer (NDO) and a tracking differentiator (TD), a dynamic surface control (DSC) is proposed in this work. Firstly, the stability of the controller is validated using the Lyapunov method. Then, experiments are conducted to verify the proposed control strategy. As a result, the hydraulic cylinder can accurately track the reference displacement signal and effectively reduce the pressure drop at the valve’s orifice, due to which the hydraulic system achieves significant energy-savings. Compared with that of the EHSS, the energy consumption of the VSP-SMEHSS is reduced by 44.6%.

scholarly journals Research on Output Signal Controlling of an Asymmetric Hydraulic Cylinder Based on a Flexible Connection

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Tao Wang ◽  
Jinchun Song
Keyword(s):  
Output Signal ◽  
Servo System ◽  
Adaptive Controller ◽  
Hydraulic Cylinder ◽  
System Response ◽  
Hydraulic Systems ◽  
Response Signal ◽  
Hydraulic Servo ◽  
Hydraulic Servo System ◽  
Flexible Connections

In industrial production, the structures of hydraulic servo system-connecting device-load systems are often simplified as rigid connections for the ease of calculation. However, this simplification is problematic when applied to flexible connections in hydraulic systems, which generally have multivariable and strong couplings; these characteristics affect the control accuracy of the hydraulic servo system and lead to serious distortion of the output waveform, which cannot be ignored. These problems cause greater lag and attenuation of the actual signal than those of the expected signal, leading to lower credibility. Therefore, it is important to study the waveform distortion caused by flexible connections. In this paper, according to the characteristics of a flexible connection, a corresponding mathematical model is established, and an adaptive controller, whose structure is simple and calculation cost is low, is used to adjust the amplitude and phase of the response signal and improve the accuracy of the system response. Treating the change in the response signal as the error value, the algorithm weights are adjusted until the error value is stable. Then, a more accurate output signal is obtained. Finally, the validity and practicability of the adaptive controller are verified by simulation experiments.

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