Electro-hydraulic Position Control Research Articles

Adaptive sliding mode controller based on fuzzy rules for a typical excavator electro-hydraulic position control system

In order to improve the trajectory tracking accuracy and robustness of a typical heavy electro-hydraulic position system, a fuzzy adaptive sliding mode controller is proposed. A potential-like function is introduced to design a new sliding surface with non-linear integral term. An adaptive controller is designed to approximate the equivalent controller in sliding mode control. Stability of the controller is demonstrated by Lyapunov method, and the chattering phenomenon caused by the nonlinear switching term is reduced by using the fuzzy switching method, 25 fuzzy rules are given to adjust the sliding mode switching controller. Simulations with sinusoidal, ramp and step signals, and experiments with leveling operation at different speeds are carried out. The proposed controller can follow the reference trajectory quickly and smoothly, and has certain anti-interference ability. Compared with the traditional sliding mode controller, the proposed controller has small tracking error, fast response and good tracking performances.

Stable Switching Control Strategy of the Support Pressure and Velocity of Shield Machine Gripper Shoes

An electro‐hydraulic servo position and pressure compound control method was investigated considering the working principle of a hydraulic stepping motor of a shield machine gripper shoe and its practical working characteristics in the supporting process. The control targets were to improve the support efficiency and reduce the disturbance of gripper shoes on the surrounding rock. In this method, a fuzzy switching controller was used to switch between electro‐hydraulic position control and electro‐hydraulic pressure control. Numerical and prototype simulation experiments were conducted on the control method. The theoretical analysis and experimental results showed that the control method could effectively convert the gripper shoes from an unsupported state to a supported state in a short amount of time, as well as realize surge‐free switching between position control and pressure control. Thus, disturbance of the gripper shoes on the surrounding rock could be reduced. The results of this study provide a theoretical basis for research on control strategies of hydraulic stepping propulsion of shield machines.

Method for combining valves with symmetric and asymmetric cylinders for hydraulic systems

Electro-hydraulic position control systems are widely applied in several fields. The valve and cylinder configuration and the dimensioning of these systems is dependent on the requested transient r...

Quantitative feedback controller design and test for an electro-hydraulic position control system in a large-scale reflecting telescope

For the primary mirror of a large-scale telescope, an electro-hydraulic position control system (EHPCS) is used in the primary mirror support system. The EHPCS helps the telescope improve imaging quality and requires a micron-level position control capability with a high convergence rate, high tracking accuracy, and stability over a wide mirror cell rotation region. In addition, the EHPCS parameters vary across different working conditions, thus rendering the system nonlinear. In this paper, we propose a robust closed-loop design for the position control system in a primary hydraulic support system. The control system is synthesized based on quantitative feedback theory. The parameter bounds are defined by system modeling and identified using the frequency response method. The proposed controller design achieves robust stability and a reference tracking performance by loop shaping in the frequency domain. Experiment results are included from the test rig for the primary mirror support system, showing the effectiveness of the proposed control design.

Investigation of Electrohydraulic Control of A Gas Turbine Engine’s Inlet Guide Vanes

Abstract: Electrohydraulic systems play a pivotal role in controlling gas turbine engines. One of the most challenging problems in electrohydraulic control systems is modeling the non-linearity of fluid behavior due to special shaped orifices. Previous published studies have not treated modeling of such hydraulic systems in much detail, although they are widely used in aircraft engines and ground vehicles equipped with gas turbine engines. Presenting a validated model for an electrohydraulic position control system is fundamental to design and compare the effect of different control techniques on the system behavior.In this paper, a detailed study of a fuel based electrohydraulic position control system was presented. This system is used in an air gas turbine engine of a ground equipment. The system controls the engine’s air inlet guide vanes (IGV) position by means of linear hydraulic actuator. This actuator, in turn, is controlled via contactless electrohydraulic servo solenoid valve. A test rig was built to expedite measuring the actual system response and controlling it. A mathematical dynamic model was derived and solved using SIMULINK, a Matlab® application. Predicted results were compared with the experimental measured results. The comparison showed that the most extreme difference between the measured and predicted results was less than 5%. Therefore, the presented model could be used to design and compare the effect of different control techniques on the system behavior for further development.

An Electro-hydraulic Position Control System with Dual-controller Switching

This article focuses on the improvement of the control performance of the electro-hydraulic position servo system. A three-order state feedback (3OSF) controller is designed to eliminate static error. For the purpose that overcome the inadequacy due to high order in the 3OSF control system, a weighted switching algorithm in the finite frequency domain is adopted to realize the switching control using the 3OSF-2OSF dual-controller. Experiments show that the control system using the 3OSF-2OSF dual-controller weighted switching in the finite frequency domain has better dynamic performance and static performance than the control system using the 2OSF. Comparing with the threshold switching, the developed switching algorithm has smaller switching impact.

Compound Compensation Control for the Electro-hydraulic Position Control System Supplied with Oil by Variable-pressure Accumulators

Compound Compensation Control for the Electro-hydraulic Position Control System Supplied with Oil by Variable-pressure Accumulators

Novel electro-hydraulic position control system for primary mirror supporting system

In the field of modern large-scale telescope, primary mirror supporting system technology faces the difficulties of theoretically uniform output force request and bias compensation. Therefore, a novel position control system combining hydraulic system with servo motor system is introduced. The novel system ensures uniform output force on supporting points without complicating the mechanical structure. The structures of both primary mirror supporting system and novel position system are described. Then, the mathematical model of novel position control system is derived for controller selection. A proportional–derivative controller is adopted for simulations and experiments of step response and triangle path tracking. The results show that proportional–derivative controller guarantees the system with micrometer-level positioning ability. A modified proportional–derivative controller is utilized to promote system behavior with faster response overshoot. The novel position control system is then applied on primary mirror supporting system. Coupling effect is observed among actuator partitions, and relocation of virtual pivot supporting point is chosen as the decoupling measurement. The position keeping ability of the primary mirror supporting system is verified by rotating the mirror cell at a considerably high rate. The experiment results show that the decoupled system performs better with smaller bias and shorter recovery time.

Design and experimental evaluation of feedforward controller integrating filtered-x LMS algorithm with applications to electro-hydraulic force control systems

The control purpose of an electro-hydraulic force control (EHFC) system is to real time replicate the force exerted on a structure in laboratory so as to simulate loads that cannot otherwise be generated naturally. In contrast to electro-hydraulic position control system, the tracking performance of EHFC system is always limited. To enhance the force replication accuracy of EHFC systems, a feedforward inverse controller integrating filtered-x LMS adaptive algorithm is presented in this paper. The proposed controller comprises a feedforward inverse controller and an adaptive controller. The feedforward inverse controller working as an inner loop is firstly established by directly cascading the designed parametric inverse transfer function to the EHFC system with proportional integral controller and the inverse transfer function is obtained with the implementation of system identification and zero magnitude error tracking technology. Then, the adaptive controller employing the filtered-x LMS algorithm acting as an outer loop is further combined with the feedforward controller to deal with the error occurred in the inverse model design procedure. Therefore, the proposed controller is an easy-to-implement strategy and can effectively enhance the force replication performance for both phase delay errors and amplitude mismatch errors. Finally, a series of experiments are carried out on a real EHFC test rig by means of xPC target technology, and the experimental results indicate that the proposed controller has a relatively better tracking accuracy compared with the proportional integral controller and the feedforward controller. It is also worth noting that the proposed controller can also be extended to other servo control systems where high accuracy tracking performance is required.

Design of the Hydraulic System of Lead Plate Coiling Machine

This paper mainly introduces the process of lead electrolysis, the structure and working principle of lead plate coiling machine and Its’ parts, coiling machine components. First of all, rewind section hydraulic system adopts a return to the oil throttle speed control, it is stable and can bear a certain change load, can overcome the stage before the tension fluctuation of the impaction to the rotation speed of hydraulic motor. Secondly, speed and tension control system adopt electro-hydraulic servo valve and proportional relief valve are respectively to the drum speed and output torque control,it has high precision and accurate in speed and tension control. contact coiling section use electro hydraulic servo position control system with close loop control to improve the accuracy of position control. Finally, calculate parameters of each working section of hydraulic control system , verify the hydraulic component model and the rationality of the hydraulic circuit.

Improvement on performance of electro-hydraulic central position control system by adaptive reaching law sliding mode method

The switching function and its change are used as input, the index reaching law parameters that represent chattering is used as output, design the switch function sliding mode control method based on fuzzy adaptive reaching index law. Applying for electro-hydraulic central position control system of single roller for a large silicon steel company, and co-simulation between the physical model of the hydraulic system and controller model is implemented, analyze the response characteristics, tracking accuracy and control chattering of the system. The research results show that the strategy has fast response, high control precision and smaller chattering. Streszczenie. Opisano metode sterowania ukladem elektro-hydraulicznym w napedzie taśmowym stosowanym w przedsiebiorstwie produkującym stal krzemową. Na wejściu analizuje sie funkcje przelączania - na wyjściu analizuje sie drgania. Do sterowania wykorzystuje sie metody logiki rozmytej. (Poprawa wlaściwości systemu sterowania ukladem elektro-hydraulicznym przez zastosowanie adaptacyjnej metody ślizgowej)

Research of Control Strategy Based on the Electro-Hydraulic Proportion Position Control System

The self-tuning fuzzy PID controller of the electro-hydraulic proportion position control system is designed and researched. Compared the self-tuning fuzzy PID control with the traditional PID control through experiments for the track effect on sinusoidal signals, the results show that the self-tuning fuzzy PID controller has higher accuracy and better stability. It is a more excellent performance controller.

Velocity Feedback Control of a Mechatronics System

Increasing demands in performance and quality make drive systems fundamental parts in the progressive automation of industrial process. The analysis and design of Mechatronics systems are often based on linear or linearized models which may not accurately represent the servo system characteristics when the system is subject to inputs of large amplitude. The impact of the nonlinearities of the dynamic system and its stability needs to be clarified. The objective of this paper is to present a nonlinear mathematical model which allows studying and analysis of the dynamic characteristic of an electro hydraulic position control servo. The angular displacement response of motor shaft due to large amplitude step input is obtained by applying velocity feedback control strategy. The simulation results are found to be in agreement with the experimental data that were generated under similar conditions.

A Multilayer Feed Forward Small-World Neural Network Controller and Its Application on Electrohydraulic Actuation System

Being difficult to attain the precise mathematical models, traditional control methods such as proportional integral (PI) and proportional integral differentiation (PID) cannot meet the demands for real time and robustness when applied in some nonlinear systems. The neural network controller is a good replacement to overcome these shortcomings. However, the performance of neural network controller is directly determined by neural network model. In this paper, a new neural network model is constructed with a structure topology between the regular and random connection modes based on complex network, which simulates the brain neural network as far as possible, to design a better neural network controller. Then, a new controller is designed under small-world neural network model and is investigated in both linear and nonlinear systems control. The simulation results show that the new controller basing on small-world network model can improve the control precision by 30% in the case of system with random disturbance. Besides the good performance of the new controller in tracking square wave signals, which is demonstrated by the experiment results of direct drive electro-hydraulic actuation position control system, it works well on anti-interference performance.

PID Studies on Position Tracking Control of an Electro-Hydraulic Actuator

Despite the application of advanced control technique to imp rove the performance of electro-hydraulic position control, Proportional Integral Derivative (PID) control scheme seems able to produce satisfactory result. PID is preferable in industrial applications because it is simp le and robust. The main problem in its application is to tune the parameters to its optimu m values. This study will look into an optimization of PID parameters using Nelder-Mead (N-M) co mpare with self-tuning fuzzy approach for electro-hydraulic position control system. The electro-hydraulic system was represented by an Auto-regressive with Exogenous Input (ARX) model structure obtained through MATLAB System Identification Toolbo x. Second-order and third-order model of the system had been evaluated. Simu lation and real-t ime studies show that the output produced the best response in terms of transient speed and Root Mean Square Error (RM SE) performance criteria.

Modeling and Simulation of Electro-Hydraulic Proportional Position Control System with the Flexible Hose

A method which utilizes the power bond graph to establish the flexible hose model is described in this work. By using this method, the paper establishes mathematical modeling for the location of electro-hydraulic proportional control system with the flexible hose. And then, this article completes dynamic simulation by MATLAB and analyses the results of simulation. The effect of the flexible hose parameters on dynamics characteristics of the hydraulic system is also studied.

Electro-Hydraulic Servo Central Position Control System of Strip Based on the Principle of Differential Capacitance

There are some problem for Strip transmission process, such as low deviation information accuracy , poor reliability, poor control results,the electro-hydraulic servo central position control system of Strip based on the principle of differential capacitance was designed. The differential connection is used for eliminating signal drift and the nonlinear characteristics，high frequency power supply is used for reducing output impedance and improving the system bandwidth, double shielded is used for eliminating the impact of parasitic capacitance, the electro-hydraulic servo central position control system based on fuzzy PID is designed. Research shows that the measuring circuit and control system are with high precision, good reliability, maintenance-free advantages.

Simulation on Electro-Hydraulic Proportional Position Control System under Pressure Boundary Conditions

Nowadays, the hydraulic straightening presses play an important role in straightening mandrels. For different mandrels, straightening forces and reductions differ. So the proportional position control system under pressure boundary conditions is required. The mathematical model of the system is deduced, and simulation of the system is carried out by MATLAB. The curves of step response and Bode diagram show that the system is steady and quick-response. The error caused by load is analyzed, which meets the straightening requirements and validates its design. The work in this paper can provide a high guidance for presses of similar kinds.

A Study on the Effects of Servovalve Lap on the Performance of a Closed - Loop Electrohydraulic Position Control System

This paper deals with a closed–loop position control of a double acting and double–rod actuator using an electrohydraulic servovalve (EHSV). This system is studied by using symmetric critical center spool valve (zerolapped) and open center spool valve (underlapped). The nonlinear dynamic behavior of each case is undertaken and simulated. The system is modeled by using five state variables (piston position, piston velocity, actuator pressures, and servovalve spool displacement) and is tested under different step inputs. The EHSV is modeled with a first order differential equation. The closed-loop system stability is investigated by introducing equilibrium state into Jacobian matrix and determining the eignvalues. Viscous friction and compressibility of oil are included in the modeling of the system. Because the electrohydraulic position servo system is not very sensitive to coulomb friction and piston leakage they are neglected. The work showed that when the underlapped servovalve operates in the underlap region, the hydraulic position control system has more stable operation and better transient responses. Keywords: Zerolap, Underlap, EHSV, Steady-State Characteristics, Dynamic Response, Position Control, Modeling, Simulation.

An experimental study on the optimization of controller gains for an electro-hydraulic servo system using evolution strategies

This paper deals with an experimental optimization problem of the controller gains for an electro-hydraulic position control system through evolution strategies (ESs)-based method. The optimal controller gains for the control system are obtained by maximizing fitness function designed specially to evaluate the system performance. In this paper, for an electro-hydraulic position control system which would represent a hydraulic mill stand for the roll-gap control in plate hot-rollings, the time delay controller (TDC) is designed, and three control parameters of this controller are directly optimized through a series of experiments using this method. It is shown that the near-optimal value of the controller gains is obtained in about 5th generation, which corresponds to approximately 150 experiments. The optimal controller gains are experimentally confirmed by inspecting the fitness function topologies that represent system performance in the gain spaces. It is found that there are some local optimums on a fitness function topology so that the optimization of the three control parameters of a TDC by manual tuning could be a task of great difficulty. The optimized results via the ES coincide with the maximum peak point in topologies. It is also shown that the proposed method is an efficient scheme giving economy of time and labor in optimizing the controller gains of fluid power systems experimentally.