Electro-hydraulic Control Research Articles

Exploring the Essence of Servo Pump Control

The electrohydraulic servo variable speed volume pump control system (hereinafter referred to as ESPCS) is integrated with a permanent magnet synchronous motor (hereinafter referred to as servo motor), a fixed-displacement pump, and a hydraulic cylinder. By controlling the servo motor speed, the output flow of the system can be controlled, as can the displacement, force, and speed of the hydraulic cylinder. Compared with the traditional electro-hydraulic servo valve control system, the ESPCS has the advantages of high power-to-weight ratio, energy saving, and environmental friendliness. However, due to the extremely nonlinear flow output of the ESPCS, further improvement of system control performance is greatly hindered. This paper focuses on the nonlinear characteristics of servo motor, fixed-displacement pump, hydraulic cylinder, and other key components in the system. A compensation method based on nonlinear characteristic mapping is proposed. Compared with the traditional PID control method (pressure control accuracy ± 0.12 MPa), the pressure control accuracy of the system is greatly improved (pressure control accuracy ± 0.037 MPa), which opens up a new way to improve the pressure control accuracy of the ESPCS.

Fuzzy Compensation and Load Disturbance Adaptive Control Strategy for Electro-Hydraulic Servo Pump Control System

Aiming at the high-precision position control of electro-hydraulic servo pump control system, a compensation control algorithm based on fuzzy control theory is proposed based on the classical PID control algorithm for the control of factors such as oil compression and system leakage. Firstly, a mathematical model of the system was established, and online identification of load disturbance was carried out. Then, oil compression and system leakage compensation controllers were established, and the position error caused by the load disturbance was compensated based on fuzzy control rules. Finally, the position control effect was verified using an experimental platform. The results show that the load disturbance compensation control strategy can significantly reduce the influence of load disturbance of the system. The steady-state accuracy of the system reached ±0.01 mm, which significantly enhanced the anti-disturbance ability of the system.

Development of Electro-Hydraulic Hitch Control System through Lower Link Draft Sensing of a Tractor

Three-point linkage plays an important role in controlling tillage implements with the hydraulic system of the tractor which includes draft control too. With increase in the usage of electronics and instrumentation in agriculture, the need was to upgrade the present mechanical hydraulic system of the tractor with electrohydraulic hitch control system (EHH) for better performance. The selection of draft sensing media was at the lower links for better sensitivity. The EHH control system through lower link draft sensing was developed using draft sensors, a control panel for user input and a controller with usage of MATLAB Simulink as an application software. Developed system was tested infield using duck foot cultivator and instrumentation like angle sensor, data acquisition and data logger were used for data capturing. The test results showed that for a change in set draft of 1500N, the system response time and change in depth of operation were 1.3s and 5 cm respectively. Whereas, for change in set draft of 500N the system response time was 0.9 s and change in depth of operation was 4 cm. For the conducted test, the variation in depth of operation was limiting to ±3.1 cm. The results concluded a direct relationship of change in set draft with system response time and change in operating depth. This study provides an overview of developing an EHH system through lower link draft sensing, as well as details of system architecture, control algorithm, MATLAB Simulink code, components used and the methodology and instrumentation technique for testing the same.

Investigation of dynamic processes in the hydraulic system of clamping the staffs of the segment unwinder of the unit of aggregation of rolls pipe welding machine 20-114

In the technological line for the production of small diameter pipes used segment un-winder staffs with a cantilever drum and additional support. The experience of its operation has shown that one of its main shortcomings is the unsatisfactory operation of the hydraulic system clamping staffs. In the hydraulic clamping system of the staffs there are increased dynamic loads, which lead to the failure of components and elements of the hydraulic system. The layout of the hydraulic clamping system of the headquarters is made for design and technological rea-sons, without taking into account the influence of pipeline lengths on the nature of dynamic processes in the hydraulic system. In addition, the hydraulic system uses spool hydrodistributors with electro-hydraulic control, the operation time of which is practically not subject to regulation. Based on the analysis of known mathematical models for the study of dynamic processes in hydraulic systems, it was concluded that as a mathematical model that takes into account the design and operation of the hydraulic clamping system staffs finite-difference method in a sys-tem of ordinary differential equations with boundary conditions described by algebraic equations. A basic dynamic model has been created, which allows to analyze with high relia-bility the behavior of the hydraulic system of the clamping mechanism of the staff in the segment unwinder of the rolls, which is exposed to different nature in a wide range of mode parameters. Simulink MATLAB software environment was used to effectively solve this problem. During the implementation of the mathematical model, a study of the modes of operation of the hydraulic system of the clamping mechanism of the staff was performed. It was found that at the end of the working and reverse strokes of the clamping mechanism of the roll in the end posi-tions there are dynamic loads in the hydraulic system that reach the maximum allowable values. In addition, it was found that during the acceleration of the piston of the hydraulic cylinder during operation and reverse, although there are no dangerous loads, but there are rapid fluctuations in pressure in the cavities of the hydraulic cylinder. Theoretical studies of the modes of operation of the hydraulic clamping system of the staff in the segment unwinder with different operating times of the control valve. As a result of the study of transients in the unwinding hydraulic system with different operating times of the hydraulic distributor, its ra-tional operating time was recommended, which is 0.20 seconds when opening and 0.15 sec-onds when closing.

An event-triggered based robust control for electro-hydraulic servo machines with active disturbances rejection

From an interdisciplinary perspective, the event-triggered scheme, the state observer, and the nonlinear disturbance observer are introduced in a robust tracking control to study the networked electro-hydraulic servo system control problems with digital communication challenge, sensor installation restricted problem, matched modeling uncertainties, and mismatched disturbances. Control packets are likely to be delayed or even lost in the networked control system when the communication medium is shared by multiple nodes and the available communication bandwidth is limited. Therefore, it is necessary to save communication resources. To improve the control performance and the efficiency of the network resource utilization, the event-triggered scheme is introduced. Specifically, the practical application of the event-triggered scheme in an actual electro-hydraulic servo system is a breakthrough in this paper. In addition, to obtain the real-time states of the unmeasurable system and compensate for both matched disturbances and external disturbances simultaneously, the state observer and the nonlinear disturbance observer are collaboratively designed. Finally, to evaluate the control performance of the designed controller, the related comparative experiments are carried out in an actual system. The results show that theoretical analysis and experimentation are cross verified.

Research on Electro-hydraulic Composite ABS Control for Four-wheel-independent-drive Electric Vehicles Based on Robust Integral Sliding Mode Control

Research on Electro-hydraulic Composite ABS Control for Four-wheel-independent-drive Electric Vehicles Based on Robust Integral Sliding Mode Control

An Electrohydraulic Force Control System for Large-Scale Force Calibration

An Electrohydraulic Force Control System for Large-Scale Force Calibration

Classical and Metaheuristic Optimizations Performance in an Electro-Hydraulic Control System

Classical and Metaheuristic Optimizations Performance in an Electro-Hydraulic Control System

Development and performance evaluation of the electric-hydraulic concave clearance control system based on maize feed rate monitoring

Complex field environments, diverse crop conditions, and varying feed rate fluctuations commonly result in a decline in the threshing performance and the clogging of the threshing cylinder for maize harvesters. In order to overcome these problems, an electric-hydraulic concave clearance automatic control system for the threshing unit was developed based on the maize feed rate monitoring, which can automatically realize the best match between the concave clearance and diverse feed rates during harvesting. The threshing performance of the electric-hydraulic control system was evaluated for varying and uneven maize feed rate fluctuations, such as the feed rate increased (6-8-10 kg/s), the feed rate decreased after an increase (6-10-8 kg/s, 8-10-6 kg/s), the feed rate increased after a decrease (8-6-10 kg/s, 10-6-8 kg/s), and the feed rate decreased (10-8-6 kg/s). In particular, the threshing rotor shaft peak torque, the range of threshing rotor shaft torque, the rate of broken grains (BGR), and the rate of unthreshed grains (UGR) with and without the electric-hydraulic control system were tested. Treatments with the electric-hydraulic control system were adjustable concave clearance with the value of 45 mm, 50 mm, and 55 mm. Treatments without the electric-hydraulic control system were constant concave clearance (50 mm). Results demonstrate that the threshing unit with the electric-hydraulic control system outperformed the one without the electric-hydraulic control system, with threshing rotor peak torque, the range of threshing rotor axis torque, the BGR, and the UGR decreasing by 18.38%, 38.27%, 2.08%, and 0.10%, respectively. Moreover, the rate of broken grains was lower than 5.00%, better than the national standard. Thus, the feed rate fluctuations and timely adjustment of the concave clearance were able to avoid blocking the rotor and improve the threshing performance compared to the constant concave clearance. Keywords: maize harvester, threshing cylinder, feed rate, concave clearance, electro-hydraulic control system DOI: 10.25165/j.ijabe.20221502.6369 Citation: Fan C L, Zhang D X, Yang L, Cui T, He X T, Zhao H H. Development and performance evaluation of the electric-hydraulic concave clearance control system based on maize feed rate monitoring. Int J Agric & Biol Eng, 2022; 15(2): 156–164.

Development and Testing of an Electro-Hydraulic System for Height Control of Sugarcane Harvester Basecutter

HighlightsThis article focuses on an automatic control system for basecutter height.The influence of three factors on the performance indexes was studied.The best parameter combination for working performance was obtained.Abstract. Precision control of the basecutter height of sugarcane harvesters is an effective method to reduce stubble damage and sugar loss. Due to uneven ground, it is difficult to maintain the desired basecutter height. Therefore, an electro-hydraulic control system for controlling the basecutter height was developed to address these issues. In this control system, an angle sensor was used to detect the basecutter height by measuring the swing angle of a profiling device. To evaluate the performance of the control system, a series of tests was conducted with a mobile cutting platform. Forward speed (1, 2, or 3 km h-1), ground wavelength (1, 2, or 3 m), and ground amplitude (4, 8, or 12 cm) were selected as influencing factors. ANOVA of the orthogonal experiment results showed that forward speed and ground amplitude had significant effects on the coefficient of variation (CV) of cutting depth, while ground wavelength had a non-significant effect. The influence order of the factors on the CV of cutting depth was forward speed > ground amplitude > ground wavelength. The best combination was determined as a forward speed of 1 km h-1, ground wavelength of 2 m, and ground amplitude of 4 cm. A single-factor test indicated that a forward speed of less than 2 km h-1 can meet the requirement that the CV is less than 10%. This study provides a reference for future design and development of automatic adjustment systems for basecutter height. Keywords: Automatic adjustment of basecutter height, Electro-hydraulic control system, Sugarcane, Sugarcane harvester.

Power Equipment Defects Prediction Based on the Joint Solution of Classification and Regression Problems Using Machine Learning Methods

Our paper proposes a method for constructing a system for predicting defects and failures of power equipment and the time of their occurrence based on the joint solution of regression and classification problems using machine learning methods. A distinctive feature of this method is the use of the equipment’s technical condition index as an informative parameter. The results of calculating and visualizing the technical condition index in relation to the electro-hydraulic automatic control system of hydropower turbine when predicting the defect “clogging of drainage channels” showed that its determination both for an equipment and for a group of its functional units allows one to quickly and with the required accuracy assess the arising technological disturbances in the operation of power equipment. In order to predict the behavior of the technical condition index of the automatic control system of the turbine, the optimal tuning of the LSTM model of the recurrent neural network was developed and carried out. The result of the application of the model was the forecast of the technical condition index achievement and the limiting characteristic according to the current time data on its values. The developed model accurately predicted the behavior of the technical condition index at time intervals of 3 and 10 h, which made it possible to draw a conclusion about its applicability for early identification of the investigated defect in the automatic control system of the turbine. Thus, we can conclude that the joint solution of regression and classification problems using an information parameter in the form of a technical condition index allows one to develop systems for predicting defects, one significant advantage of which is the ability to early determine the development of degradation phenomena in power equipment.

Position Output Adaptive Backstepping Control of Electro-Hydraulic Servo Closed-Pump Control System

A nonlinear adaptive backstepping control method was proposed to address the system parameter uncertainty problem in the position control process of an electro-hydraulic servo closed-pump control system. This control strategy fully considers the parameter uncertainty of the nonlinear system and establishes the adaptive rate of the uncertain parameter to adjust the parameter disturbance online in real time, thereby improving the accuracy and robustness of the control system. A pump control system experiment platform was used to verify the feasibility of the controller. The experimental results showed that the proposed control strategy provided a good control effect. The pump control system can be controlled with high precision, with a steady-state control accuracy of ±0.02 mm, which serves as a good foundation for the engineering application and promotion of the pump control system.

Design and Simulation of Electro-hydraulic Control Valve Based on AMESim

In this paper, the electro-hydraulic control valve commonly used in ships is taken as the research object, the working principle of the valve is introduced, the model of the valve is established by AMESim software, the model parameters are set and the simulation analysis is carried out. By changing the relevant parameters of the valve, the response speed of the valve can be improved. The simulation results show that the pressure area of load sensitive cavity and the diameter of damping hole have obvious influence on the response speed of valve.

Combined Control Mechanism of Weight on Bit and Rate of Penetration with a Downhole Robot in the Coiled-Tubing Drilling Process

Summary Downhole robots were used to solve the problem of downhole tool transportation in an oil/gas horizontal well. However, current downhole robots do not control the weight on bit (WOB) and rate of penetration (ROP). This paper proposes the combined control method of WOB and ROP using an electric proportional overflow valve (EPOV) and an electric proportional throttle valve (EPTV). First, the mathematical model of the electrohydraulic control of the downhole robot is established. It is found that when the maximum pressure of the EPOV is greater than the differential pressure between the inner and outer of the downhole robot, the control parameters are drilling-fluid displacement and circulation area of the EPTV. When the maximum pressure of the EPOV is less than the differential pressure between the inner and outer of the downhole robot, the control parameters are drilling-fluid displacement, circulation area of the EPTV, and pressure of the EPOV. Moreover, it is found that the relationship of WOB and ROP in the combined control method is a surface rather than a line in a 2D coordinate. Therefore, the downhole robot can be adjusted while drilling at a stable ROP or a stable WOB. Finally, the combined control method of WOB and ROP with the downhole robot proposed in this paper was verified with an experiment. According to the experimental data, it is further found that an EPOV cannot only control WOB and ROP, but also can control the upper limit of WOB fluctuation. Thus, the control of WOB fluctuation can protect the bit from damage and prolong the life of the bit. This paper presents a foundation for the control of WOB and ROP with downhole robots. It has scientific and engineering significance for promoting downhole robots in drilling engineering.

Control efficiency improvement of an electro-hydraulic winch

The paper presents a study regarding electro-hydraulic control systems for drive winches, a structural part of LARS (Launch and Recovery Systems). In the Introduction section of the paper, the authors present the domains of the research vessel. Furthermore, there is presented the importance of launch and recovery systems (LARS) and drive winches on the deck of a research vessel. The launch and recovery systems (LARS) using drive winches are installed on the stern of the research vessel. Further in the paper, the authors present the results of studying three simplified systems that use electric, hydraulic and electro-hydraulic driving solutions. Furthermore, there are presented comparative advantages of using this three types of drive winches. At the end of the paper, the authors perform an analysis of the electro-hydraulic systems for the drive winch, using a modelling and simulation software. Each schematic is presented along with its components. Moreover, the authors mention that all the schematics presented in this paper are modelled using FluidSim software from FESTO. In this case, only three mathematic relations are used in the paper: the Cauchy momentum (convective form), the incompressible Euler relations and the pressure losses in the hydraulic and electro-hydraulic drive winch.

Robust Nonlinear Control Scheme for Electro-Hydraulic Force Tracking Control with Time-Varying Output Constraint

This paper presents a robust nonlinear control scheme with time-varying output constraint for the electro-hydraulic force control system (EHFCS). Two typical double-rod symmetrical hydraulic cylinders are employed to simulate force environments in the EHFCS. Therefore, in order to improve the performance of the EHFCS, firstly, the model of the EHFCS is established with taking external disturbances, parameter uncertainties as well as structural vibrations into consideration. Secondly, in order to estimate external disturbances, parameter uncertainties and structural vibrations in the EHFCS and compensate them in the following robust controller design, two disturbance observers (DOs) are designed according to the nonlinear system model. Thirdly, with two estimation values from two DOs, a time-varying constraint-based robust controller (TVCRC) is presented in detail. Moreover, the stability of the proposed controller is analyzed by defining a proper Lyapunov functions. Finally, in order to validate the performance of the proposed controller, a series of simulation studies are conducted using the MATLAB/Simulink software. These simulation results give a fine proof of the efficiency of the proposed controller. What’s more, an experimental setup of the EHFCS is established to further validate the performance. Comparative experimental results show that the proposed controller exhibits better performance than the TVCRC without two DOs and a conventional proportional integral (PI) controller.

Modeling, simulation and experimental validation of flow rate of electro-hydraulic hitch control valve of agricultural tractor

Advances in non-linear control theory have made it possible to develop controllers for non-linear dynamic systems in their nature. The low-cost proportional control valves of the hydraulic control system are examples of such a system where there is no linearity due to the structure of the valves and the flaws in the spool. However, the non-linear analysis and regulation of these hydraulic systems cannot be done without a proper valve model. This paper presents a methodology for the development of an efficient unified model of a three-point hitch (TPH) electro-hydraulic proportional control valve control system for agricultural tractors by means of a parameter estimation technique. Modeling and simulation of the proportional control valve was performed using MATLAB Simulink software. Parameter estimation methodology was used to optimize the effective orifice opening of the solenoid valve to meet the flow characteristics available in the manufacturer's technical data sheet for the proportional control valve model parameters. Such unified Simulink models are useful for simulation, practical capability testing, and non-linear control design. Modeling and simulation of electro-hydraulic hitch (EHH) control valve were made and simulation results were compared with actual experimental results. The simulation results of the TPH lifting and lowering time were found to vary 4 and 12.5 %, respectively with the experimental results. This type of parameterized valve models facilitates their implementation in dynamic simulation models of complex hydraulic systems.

Design, simulation, and experiment research on fast control system of steam turbine inlet valve

In this paper, a new fast control system of steam turbine inlet valve is designed, which is composed of the fast closing system and the fast opening system. For the first time, this paper proposes that the fast closing system is designed by means of the special structure of the slide valve in an oil servo motor on the basis of the transformation of the hydraulic control system of steam turbine inlet valve. For the first time, a differential oil discharge fast opening system is designed by use of two cartridge valves. The mathematical model of electro-hydraulic fast control system is presented. With the use of simulation software Advanced Modeling Environment for Simulation of engineering systems , the curves of parameters such as piston displacement, piston velocity, oil pressure of upper and nether cavities of oil servo motor, and flow flux of upper and nether cavities of oil servo motor are obtained. The fast closing time of the piston for whole journey from the simulation results is 0.36 s. The fast opening time of the piston for whole journey from the simulation results is 1.55 s. According to the designed structure of the fast control system, the fast control experiment system is built. The fast closing time of the piston for whole journey from the experiment results is 0.22 s. The fast opening time of the piston for the whole journey from the experiment results is 1.97 s. The simulation and experimental results show that the designed fast control system can realize the fast closing and fast opening of the inlet valve. The fast closing time of the fast control system is <0.5 s, and the fast opening time of the fast control system is <3 s, which meets the fast control time requirement of the steam turbine inlet valve. Compared with the existing fast control system products, the fast control system and the inlet valve servo regulation system share a set of oil sources. And the fast control system has the advantages of low cost, simple structure, easy implementation, etc.

Introduction of degradation modeling in qualification of the novel subsea technology

All-electric systems are the novel subsea technology that is an upgrade of widely deployed electro-hydraulic control systems. They promised more reliable equipment and a safer environment. An all-electric production system performs several functions related to hydrocarbon production control. It also performs safety functions by isolating the reservoir from the environment. Safety functions are performed by activation of safety valves. These safety valves include electric springs in their design instead of mechanical springs. Failure modes and effects analysis of these valves show that interruptions in the power supply appear as random demands to the safety valves, and experiencing such demands may deteriorate their performance. However, the current reliability assessment of safety valves does not consider any degradation phenomena. This paper’s main objective is to investigate the degradation modes caused by demands and their influence on the all-electric actuation system’s performance under different maintenance strategies. A degradation modeling framework based on the multiphase Markov process is proposed. The impact of demand is modeled by changing the initial condition or by increasing the transition rates between two degraded states. The amplitude of the increment depends on the condition at the time of the demand. Analytical formulae are developed for the time-dependent reliability assessment.

High-accuracy electrohydraulic control system for the position and orientation of the primary mirror for a large telescope

High-accuracy electrohydraulic control system for the position and orientation of the primary mirror for a large telescope