Papers by Keyword: Electro-Hydraulic Servo System

Abstract: Electro-hydraulic servo system has more disturbance and noise factors at low speed than in other situations of the whole operating process, so the stability and performances of the system would be greatly affected by these factors. It is generally accepted that nonlinear torque disturbance is the main interference factor. In order to compensate above disadvantages, a sliding mode variable structure control was proposed to adjust the electro-hydraulic servo system. The results indicate that the provided approach possesses satisfactory performances in stability, robustness, steady state error and so on.

Abstract: A novel internal force decoupling control strategy of hyper-redundant shaking table based on stiffness matrix is proposed in this paper. The linear models of electro-hydraulic servo system and mechanical system are built by considering the shaking table moving in a small range around the zero point. Internal forces are given through a transformation of cylinder forces which can be acquired from the pressure sensors. By meshing top platform of the shaking table in different directions, the stiffness matrix between the redundancy displacements and internal forces are given through dynamics equations including inertia and shear parts. The IFDC controller is designed to feedback the redundancy displacement caused by internal forces to the input current of the servovalve. Simulation results show that the proposed method is capable to reduce internal forces effectively.

Abstract: The electro-hydraulic position servo control system is a typical complex nonlinear system. It is difficult in achieving the control which has high quality performance.To overcome the effects of non-linearity, parameter uncertainty, external disturbances and load changes, the design of controller is particularly critical. This paper summarizes the controllers which are applied widely: PID controller, fuzzy controller, neural network controller and hybrid controller. Additionally, the paper analyses their performances. At the same time, this paper also points out the prospects of the controllers.

Abstract: Dynamical mathematical model was established for accurately positioning, fast response and real-time tracing of electro-hydraulic servo control system in railway vehicle bogie parameters test system with elastic load. The model could precisely control the output of position and force of the hydraulic cylinders. Induction methods was proposed in the paper. Dynamical simulation verified the mathematical model by software simulink. 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 .

Abstract: Electro-hydraulic servo system of stick support mechanism was set up, which was used to simulate the attack angle mechanism in wind tunnel. The compound control strategy with speed feed-forward and position feedback was presented. The speed feed-forward model was deduced. And the reasonable speed and position signals were designed, by which the undisturbed switching of the speed feed-forward control and the position feedback control was realized. The hydromechatronic model of electro-hydraulic servo system of stick support mechanism was established by co-simulation technology with AMESim and Motion. The simulation and experiment results conform to theoretical analysis and show that the position and speed of the cylinder can be controlled simultaneously with the technology of speed and position hybrid control.

Abstract: In wind tunnel experiments, in order to adjust the attack angle continuously, the support mechanism movement should be steady and smooth. However, the electro-hydraulic servo system is a typical nonlinear, time-varying and uncertainty system, and the wind tunnel environment is very complicated. To address these problems, an on-line identification and generalized predictive control (GPC) strategy is proposed in this study. Firstly, the Labview and AMESim are integrated to build an electro-hydraulic system simulation model. Secondly, the controlled auto-regressive moving average (CARIMA) model of the electro-hydraulic system is developed. Thirdly, the influence on the system performance owing to the control parameters, model parameters, and external disturbance are widely discussed and deeply analyzed. At last, a test platform is constructed with the National Instruments (NI) embedded real time technology. The proposed control strategy is tested and verified on this test platform. The experimental results show that the angular velocity control precision reaches 0.01°/s. It implies that this control strategy has a good performance for nonlinear velocity control. Thus it satisfies the requirement of the continuously adjusting attack angle in wind tunnel experiments.

Abstract: The aim of this paper is design a controller for force control of an Electro-Hydraulic System and selection of a PID gains are using genetic algorithm. The mathematical model is considered as the Newton second law and compressible fluid flow theory. This paper compares two kinds of tuning methods for PID controller. One is the controller design by the genetic algorithm, second is the controller design by the Ziegler and Nichols method. Each PID gains are tested with step input function, square signal, half-sine signal and half-saw signal. And results show performance index with rise time, settling time and Maximum %OS. It was found that the proposed PID gains tuning by the genetic algorithm is better than the Ziegler & Nichols method.

Abstract: For traditional direct drive volume control electro-hydraulic servo system, the servo motors rotary inertia is limited strictly, the speed of response is slow and the actuators reciprocating motion characteristics are not consistent. In order to solve these problems, this paper designs a kind of high power direct drive differential volume control electro-hydraulic servo system. It is instructive for design of hydraulic system which demands high output power, changes direction of motion frequently, needs high response frequency and requires the speed of reciprocating motion keep consistent.

Abstract: With the electro-hydraulic servo mechanism is more and more widely used in aerospace, manufacturing industry and agricultural machinery, its control performances are required by process environment with more and more expectations, which include increasing response speed and improving tracking accuracy. Because the traditional PID controller possesses large overshoot, long conversion time, bad robustness and other shortcomings, the double-loop robust control algorithm is proposed. Simulation results show that, compared with traditional PID control scheme, the proposed control scheme can achieve accurate tracking of electro-hydraulic servo system quickly. Therefore, it enhances product performance, optimizes the design process, and also possesses a high application value.

Abstract: The co-simulation method of one large electro-hydraulic servo system based on software interface is proposed in this paper. The rigid-flexible-coupling dynamic model of the electro-hydraulic servo mechanism was built through data exchange of SolidWorks, ANSYS and ADAMS, the hydraulic system model and control system framework was built by EASY5 environment, the controller was built by Simulink. The integration of simulation models for the large electro-hydraulic servo system was realized by software interfaces. In view of the poor operation conditions, the high requirement of control precision and real-time characteristics, adaptive fuzzy sliding mode control strategy was applied to position tracking control of the servo system. Simulation results verified the effectiveness of this method.