Electro-hydraulic Servo Control Research Articles

Study on Dynamical Simulation of Railway Vehicle Bogie Parameters Test-bench Electro-hydraulic Servo System

Abstract Dynamical mathematical model was established for accurately positioning, fast response and real-time tracing of electro-hydraulic servo control system in railway vehicle bog ie parameters test system with elastic load. The model could precisely control the output of position and force of the hydraulic cylinders. Induction method was proposed in the paper. Dynamical simulation verified the mathematical model by SIMULINK software. Meanwhile the key factors affecting the dynamical characteristics of the system were discussed in detail. Through the simulation results, high precision is obtained in application and the need of real-time control on the railway vehicle bogie parameters test-bench is realized.

A Nonlinear PID Controller for Electro-Hydraulic Servo System Based on PSO Algorithm

Linear PID controller is adopted by electro-hydraulic servo system widely. The proportional, integral and derivative coefficients of a linear controller are fixed which brings the contradiction in speediness and overshoot. This paper designs a series of nonlinear functions which are used for nonlinear PID control for electro-hydraulic servo system. The proportional, integral and derivative parts of this nonlinear PID controller adjust themselves according to the error. In order to determine parameters of the nonlinear functions, PSO Algorithm and ITAE guideline are applied in the paper. Results of simulation indicate that the nonlinear PSO-PID controller using the functions proposed in this paper presents a better dynamic response than the linear PID controller.

Adaptive Position Control of an Electrohydraulic Servo System With Load Disturbance Rejection and Friction Compensation

Electrohydraulic servo systems (EHSS) are used for several engineering applications, and in particular, for efficient handling of heavy loads. These systems are characterized by pronounced nonlinearities and are also subject to parameter variations during operation, friction effects, and variable loads. Several studies have addressed the nonlinear nature of EHSS; however, only a few control schemes explicitly address friction and load disturbance effects along with parameter variations. Fuzzy and/or sliding mode versions of feedback linearizing controllers have been used to compensate for the external loads disturbances in the control of EHSS. However, real-time implementations issues limit the use of these techniques. While adaptive control using a feedback-linearization based controller structure has been shown to be effective in the presence of parameter variations, load and friction effects are typically not considered. In this paper, we present a nonlinear adaptive feedback linearizing position controller for an EHSS, which is robust to parameter uncertainty while achieving load disturbances rejection/attenuation and friction compensation. The adaptation law is derived using a Lyapunov approach. Simulation results using the proposed controller are compared to those using a nonadaptive feedback linearizing controller as well as a proportional-integral-derivative (PID) controller, in the presence of torque load disturbance, friction, and uncertainty in the hydraulic parameters. These results show improved tracking performance with the proposed controller. To address implementation concerns, simulation results with noise effects and valve saturation are also presented.

Design of Automatic Assembly Tire Machine

This system realizes the function of automatic tire assembly which not only took PLC as control center but also synthetically applied with converter, servomotor and hydraulic. Firstly, it completes the carry of tire with converter by the way of different frequency. Secondly, PLC is used to control servomotor to finish assembling of tire. Thirdly, exact position control is designed through the use of the electro hydraulic servo control. Farther more, mathematics model is established. At the end of this paper, we compare machine efficiency with the manual operation and present the application foreground of this system.

Application of Direct Actuated Digital Servo Valve in Electrohydraulic Static Loading System

Structure static testing is an important means to study the static characteristic of complex engineering structure. Electrohydraulic stactic loading system is the singnificant equipment of the testing. With its function of transfering low-power electrical singal to large-power hydraulic output quickly and precisely, the servo valve plays a key role in an electrohydraulic servo control system and dominates to a large extent the performance of the whole control system. Conventional electrohydraulic servo or proportional control is subject to the nonlinearites of their electro-mechanical interface, such as hysteresis, saturation and finite resolution. In this paper, a direct actuated digital servo valve was applied in electrohydraulic static loading system. It can be driven directly by computer needn’t D/A and has the advantages of simple structure, high tolerance to contamination and high reliability. Practical load-experiment results show that the static loading system with a direct actuated digital servo valve can work steadily and reliably and possess high accuracy and fast response.

Research on Joint Simulation and Modeling of Electro-Hydraulic Position Servo System Based on Simulink and AMESim

The uncertainty of system parameters is not considered in traditional transfer function model of electro-hydraulic servo system, and then the accuracy of analysis is affected. Therefore the physical model of electro-hydraulic servo control system is established in simulation software AMESim platform. The system controller model is builded in the control simulation software Matlab/Simulink platform. The co-simulation interface technology is used to achieve joint simulation of electro-hydraulic servo control system.

The Research for Electro-Hydraulic Servo Control System Based on Fuzzy PID

Electric-hydraulic servo system is a nonlinear and uncertain system with time-varying parameters and interference. The fuzzy PID control algorithm is used,which not only keep the flexible characteristic of fuzzy control algorithm but also inherit the traditional PID control algorithm advantages of high control precision. Research shows that fuzzy PID control has the character of fast response speed, rising fast, small lag, small overshoot, anti-interference, do not depend on the accurate model.

Simulation Technique of AMESim Applied in Mould Electrohydraulic Servo Control System

Taking electrohydraulic servo control system used in mould oscillation in bloom continuous casting machine as the object of research, AMESim software is used to establish the model of the electrohydraulic servo control system ,also simulate and analysis the system,which theoretically confirms the reliability of the electrohydraulic servo control system.The software is also used for dynamic analysis about the control system.

Research of Pump- Control Electro-Hydraulic Servo System Based on Multi-Mode Extension Control

Aiming at the contradiction between rapid response, stability and accuracy in position control of pump-control electro-hydraulic servo system, a multi-mode extension control electro-hydraulic servo system was proposed, applying extension method in system design. According to the characteristic information of the system, correlation function was established by multi-mode extension control switch. The movement process was divided into three parts according to correlative degree and controlled in each zone by Bang -Bang controller, fuzzy controller and PID controller respectively. Simulation results showed that the system had rapid response and strong robustness, and can realize high precision control.

Amplitude phase control for electro-hydraulic servo system based on normalized least-mean-square adaptive filtering algorithm

The electro-hydraulic servo system was studied to cancel the amplitude attenuation and phase delay of its sinusoidal response, by developing a network using normalized least-mean-square (LMS) adaptive filtering algorithm. The command input was corrected by weights to generate the desired input for the algorithm, and the feedback was brought into the feedback correction, whose output was the weighted feedback. The weights of the normalized LMS adaptive filtering algorithm were updated on-line according to the estimation error between the desired input and the weighted feedback. Thus, the updated weights were copied to the input correction. The estimation error was forced to zero by the normalized LMS adaptive filtering algorithm such that the weighted feedback was equal to the desired input, making the feedback track the command. The above concept was used as a basis for the development of amplitude phase control. The method has good real-time performance without estimating the system model. The simulation and experiment results show that the proposed amplitude phase control can efficiently cancel the amplitude attenuation and phase delay with high precision.

An Intelligent Electro-Hydraulic Servo Drive Positioning

The goal of the research is to develop a closed loop control system for position control of electrohydraulic servo drive useful for practical application. The research was performed based on the theory of adaptive feedback systems. The proposed new control structure consists of three parts. The first part is actually a feed-forward digital filter in the form of an inverse model of the system, which enables a perfect reference tracking behaviour. The second part is a position feedback fuzzy logic controller designed as a self-learning system, which possesses an ability of automatic tuning and is able to cope with parameter and load changes of the control loop. The third part is the so called switching integrator involved to improve steady state errors and ensure precise final positioning. The effectiveness is proven by laboratory experimental investigations.

Modeling and Co-Simulation for Hydraulic System of Test-Bed of Semi-Automatic Coupler Draft Gear Based on AMEsim/Simulink

When the test-bed tests semi-automatic coupler draft gear of the metro vehicle in the case of maximum lateral swinging angle, it requires a hydraulic motor to move the adjustable bearing base which is linked with coupler draft gear in a certain distance until it achieves the desired Angle. In this article, we adopt the valve-control motor electro-hydraulic position servo control system, in which it has the angular measuring device. Besides we optimize the effection of control system by using the fuzzy strategy. Through the AMEsim/Simulink co-simulation and analysis, the level swinging angle of coupler draft gear shows accurate, reliable and stable, which reaches the expected effection completely. With the more and more complex of the controlled object, this kind of intelligent control strategy gives an effective solution for solving complex problems.

Hydraulic drive test platform of automatic underwater welding

Because welding repair of nuclear power plant at the underwater environment, in order to simplify the sealing and increase the safety of test equipment, hydraulic drive automatic welding platform was designed that provides the relative motion required during underwater welding; Through PLC control electro-hydraulic servo valve to control welding slider's movement. Oscillating center sensor realized the track of oscillating center. Movement of welding was controlled through the manual control box. The whole system stable and reliable and can meet the needs of underwater welding.

Electro-Hydraulic Servo Control System Based on a Novel Generic Model Control Method

Abstract A novel electro-hydraulic servo control algorithm was introduced. The primary idea of this algorithm was to combine the notion of model prediction with the generic model control (GMC). The performance of the GMC algorithm was improved by receding optimization and feedback correction. By the predictive model of output errors of an electro-hydraulic servo control system based on the improved weighted least square support vector machines (WLS-SVM) to forecast and compensate the future sequence errors, the control precision and robustness were improved. The improved GMC based on the improved WLS-SVM was applied to an electro-hydraulic servo control system for hot strip rolling control systems. The simulation results showed the feasibility and effectiveness of the present algorithm.

Electro-Hydraulic Servo Control Based on CMAC Neural Network for Excavating Robot

In this paper the electric-hydraulic servo system for excavating robot is analysed. The kinematic and the dynamic model of working equipment are established. Aim at the electric-hydraulic servo system of the feature with many variables, strong coupling and non-linear, the CMAC neural network was presented combined with popular PD algorithm, which could realize intelligent control for the working equipment of excavating robot. The result of simulation show that control strategy features higher precision and robustness.

Fuzzy iterative learning control of electro-hydraulic servo system for SRM direct-drive volume control hydraulic press

A new kind of volume control hydraulic press that combines the advantages of both hydraulic and SRM (switched reluctance motor) driving technology is developed. Considering that the serious dead zone and time-variant nonlinearity exist in the volume control electro-hydraulic servo system, the ILC (iterative learning control) method is applied to tracking the displacement curve of the hydraulic press slider. In order to improve the convergence speed and precision of ILC, a fuzzy ILC algorithm that utilizes the fuzzy strategy to adaptively adjust the iterative learning gains is put forward. The simulation and experimental researches are carried out to investigate the convergence speed and precision of the fuzzy ILC for hydraulic press slider position tracking. The results show that the fuzzy ILC can raise the iterative learning speed enormously, and realize the tracking control of slider displacement curve with rapid response speed and high control precision. In experiment, the maximum tracking error 0.02 V is achieved through 12 iterations only.

Application of self-tuning fuzzy PID controller for a SRM direct drive volume control hydraulic press

A new kind of volume control servo hydraulic press driven directly by Switched Reluctance Motor (SRM) is presented in this paper. In considering the saturation and dead zone nonlinearity as well as the time-variability and the time lag existed in SRM direct drive volume control system, a fuzzy PID control method is introduced to improve the overall performance of the electro-hydraulic position servo system. The relationships between the PID parameters and the response characteristics of electro-hydraulic position servo system are investigated. The fuzzy inference rules which enable adaptive adjustment of PID parameters are established based on the error and change in error. The simulations and experiments of step response and cosine tracking are carried out on the SRM direct drive hydraulic press. The results indicate that the fuzzy self-tuning PID method has great ability of restraining external disturbance, and it can effectively raise the position tracking ability of the volume control electro-hydraulic servo system.

Nonlinear Modeling and Control of Electro-hydraulic Servo System of Pipe Expanding Procession

In order to investigate the influence of nonlinearity of valve controlled cylinder on the performance of electro-hydraulic servo system, based on electro-hydraulic servo system of pipe expanding procession, firstly the nonlinear character of valve’s electrical signal input to spool position and spool position to cylinder piston displacement output is analyzed, then a nonlinear model on asymmetry cylinder actuated by asymmetry valve is provided to represent the actual system. Secondly, according to two-step character of the actual system model, a nonlinear control approach with quantitative feedback theory (QFT) and perturbation estimation (PE) is put forward to realize the respective control of load motion and load pressure nonlinear dynamics. Finally, compared with conventional PID control, the validity of the proposed control approach is tested by simulation and actual control application. Results show that the proposed algorithm has better dynamic and static response performance. This method provides a useful tool for solving practical engineering problems.

PID Controller Optimization by GA and Its Performances on the Electro-hydraulic Servo Control System

A proportional integral derivative (PID) controller is designed and attached to electro-hydraulic servo actuator system (EHSAS) to control the angular position of the rotary actuator which control the movable surface of space vehicles. The PID gain parameters are optimized by the genetic algorithm (GA). The controller is verified on the new state-space model of servo-valves attached to the physical rotary actuator by SIMULINK program. The controller and the state-space model are verified experimentally. Simulation and experi-mental results verify the effectiveness of the PID controller adaptive by GA to control the angular position of the rotary actuator as com-pared with the classical PID controller and the compensator controller.

The Swashplate Angle Control of a Variable Displacement Pump with an Electro-Hydraulic Proportional Valve

In this paper, the mathematic model of the swashplate type variable displacement axial piston pump (VDAPP) is established. The VDAPP applied to an electro-hydraulic servo control system usually induces unstable performance, so that a servo controller is designed and analyzed to control the swashplate angular displacement and improve the stability and transient response of pump performance. The flow and pressure variations of pump with the proposed controller are investigated and analyzed by mathematic simulations and experiments. The simulation and experiment results show that the proposed controller can improve the stability of swashplate angular displacement, and easily applied to the energy saving hydraulic systems.