Search

This study presents a new method for high-speed joining of the sheet to the end of a tube without the need for any additional processes. Joining of the AA3105 sheets to the AA1170 tube is carried out with a thickness of 0.5 mm. The process is performed using electro-hydraulic forming which is a local deformation of the tube and sheet. In this method, the mechanical force is transmitted by working media in a very short time. The shock wave accelerates the panel sheet towards the die and tube to create a form-fit joint. To avoid friction between the mandrel and the flat sheet, the panel sheet is pre-drilled. The experimental tests were performed to show the effect of process parameters including; washer housing angle, sheet hole diameter, and the gap between the mandrel and top of the sheet. In addition, pull-out test is utilized to determine the strength of the joints in different conditions. Accordingly, the usage of electro-hydraulic forming on joining thin tubular parts to flat sheets was successful and the feasibility of this technique as an advanced joining approach was verified.

Today, brain attack disorders are one of the most life-threatening areas in the medical era, which mankind is facing nowadays. Globally, more than 10,000,000 people are subjected to brain attack disorders like hemiplegia and tremor, every year, where two-thirds of them survive. Among the survival community, more than 80 per cent of them are subjected to long-term impairment of their upper extremity. In order to treat the impairment, the survival group is subjected to medications and rehabilitation in order to improve their daily living. But the facilities are very limited in fast- developing countries like India when compared to western standards. The rehabilitation given corresponding with medications during the treatment period in hospitals does not give a complete recovery from disability. People from rural background could not meet their rehabilitation requirements even in the hospital during treatment and also when they are discharged to home after treatment from hospitals due to financial constraints and reachability. In order to motivate the survival group to fulfill their daily living and improve their lifestyle, this paper is focused on intelligent home-based rehabilitation system at low cost, reliability, and affordability. One major movement disorder namely Upper Arm Hemiplegia was taken into account and visited few major hospitals around Coimbatore and Chennai for literature and case study. The facilities available in various hospitals and their drawbacks were analyzed. Based on the studies conducted at hospitals and taking advice from therapists, an innovative low-cost home-based rehabilitation device using Electro-Hydraulic systems has been developed to support patients who were used to impaired living even after treatments. To support Upper Arm Hemiplegia patients, the devices which were developed and experimented to hold different functionalities are discussed in this paper.

Hydraulic systems fed by fixed displacement pumps driven by frequency-controlled electric motors can replace conventional throttling systems due to their ability to control the speed of hydraulic cylinders regardless of the value and direction of the load. These systems can improve the energy efficiency of the drive or even provide the possibility of energy recuperation during lowering. This paper presents experimental studies of the new drive system with volumetric control of the speed of the lifted/lowered payload using the example of a scissor lift. The system uses a reversible gear pump driven by an asynchronous motor fed by a frequency inverter operating in field-oriented control mode. Comparative studies of the mapping of the assumed speed of the hydraulic cylinder and platform are presented, as well as studies of the influence of the load change on the speed and positioning of the mechanism driven by the open-loop controlled system.

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.

Here, a model‐free linear active disturbance rejection controller (LADRC) integrating dead‐zone inverse compensation for an electro‐hydraulic proportional (EHP) system with an unknown dead‐zone is proposed. Unlike the existing LADRC design idea, the presented method uses a new hydraulic system block diagram to select the order of LADRC instead of the highest degree of the system. Furthermore, the rationality of order selection is illustrated by the frequency domain analysis theory. To solve the dead‐zone of the proportional valve, a novel structural transformation is proposed by constructing a new dead‐zone, which has a definite physical meaning and can be obtained by the experimental measurement. Then, the dead‐zone disturbance is reduced, and the burden of the observer is relieved. At the same time, the controller parameters are decreased from three to two equivalent PI controller. Besides, the stability of the closed‐loop system is analysed by the describing function method. The performance of the proposed control solution has been investigated through extensive comparative experiments under different working conditions. The experimental results successfully demonstrate the effectiveness and practicality of the presented method.

In this paper, an optimal robust adaptive fuzzy backstepping control is presented to the position control of the electro-hydraulic servo (EHS) system in the presence of structured and unstructured uncertainties. Initially, the robust control using the backstepping technique is presented to overcome the existing uncertainties in the dynamic equations. Mathematical proof demonstrates that the closed-loop system in the presence of uncertainties has a global asymptotic stability. Then, to overcome the chattering problem, a very simple fuzzy approximator is presented where it approximates the bounds of the uncertainties. Although the proposed robust fuzzy backstepping control has a desirable performance, it has no mathematical analysis to prove the stability of the closed-loop system. Therefore, to solve this problem, the proposed fuzzy approximator has been transformed into a one-law adaptive fuzzy approximator with a single-input single-output fuzzy rule. Mathematical analysis illustrates that the closed-loop system in the presence of uncertainties has a global asymptotic stability under the proposed robust adaptive fuzzy backstepping control. Furthermore, a novel modified harmony search algorithm (MHSA) has been developed, by using the original harmony search algorithm (OHSA) as an optimization technique, to achieve the optimal values of the membership functions and the control coefficients. Finally, a comparative study has been conducted between the proposed control scheme under the MHSA and the OHSA, and other existing advanced control approaches to verify the effectiveness of the proposed control. Results show that the proposed control scheme under the MHSA can suppress the chattering problem and reduce the disturbances effectively while ensuring that the performance is tracked.

In this article, an adaptive dynamic surface control method with nonlinear disturbance observers is proposed for accurate position tracking of an electro-hydraulic servo system with unknown time-varying inner or external disturbances. The dynamic surface control approach adopted in the proposed controller is used to ameliorate the inherent complexity differentiation explosion of traditional backstepping method, which significantly simplifies the controller design process. The designed nonlinear disturbance observers are exploited to online estimate the inner or external disturbances of electro-hydraulic servo systems, and the performance degradation resulted from unknown time-varying disturbances is effectively suppressed. To further compensate for the system’s time-varying uncertain parameters, parameter adaptive updating laws are designed and combined in the proposed controller for accurate position tracking of electro-hydraulic servo systems. The closed-loop stability of the proposed controller is theoretically guaranteed by rigorous Lyapunov analysis. Comparative experimental results are carried out on a typical single-degree-of-freedom electro-hydraulic servo system, and the feasibility together with the superiority of the proposed controller is experimentally validated.

To explore the spool orifice’s particle motion and erosion morphology in an electro-hydraulic servo valve under a small opening, a modeled particle motion visualization test and CFD calculation were conducted to study typical particle trajectory. The influence of pressure differential, particle shape, and particle diameter on the erosion rate along the working edges was discussed. The erosion characteristic morphology and working edges’ fillet diameter distribution were measured and analyzed. There are four typical particle motions: translation and spin on the wall faced the flow, translation and turn on the backflow wall, carried motion by the mainstream and particle rotation in a vortex. A model of the erosive particle motion of the spool orifice was built based on the visualization test and CFD. During these motions, the microscopic scraping and collision of particles with the working edges are the main causes of erosion wear. The erosion wear rate of the working edge is proportional to the pressure differential and the non-roundness of the particles. The fillet of a working edge periodically increases or decreases with the circumferential angle, which occurs due to the morphology and is consistent with the erosion wear rate distribution along the working edge.

Accurate posture control of hydraulic roof supports, which use pressurized water as their fluid power source, is an important part and research direction of intelligent fully mechanized mining face. At present, the large flow on/off directional valve used on the hydraulic roof support cannot meet the requirement of precise posture control of the roof support. To overcome the conundrum, a novel two-position three-way electro-hydraulic proportional directional flow valve for hydraulic roof support is proposed. The new valve contains two pilot stages and two main spools. The two pilot stages cooperate with each other to control the movement of the two main valve spools, which are the inlet valve spool and the outlet valve spool. The inlet valve spool adopts the Valvistor principle. The valve can realize manual pilot control and electro-hydraulic proportional flow control of the passage P-A, which has been verified by a simulation model. In this paper, the static and dynamic mathematical models of the new proportional valve are established, and the key parameters affecting the valve performances are analyzed and verified by the simulation model. An optimization control scheme is proposed to overcome the influence of supply pressure, P-A pressure difference, and nonlinear interference force on steady-state displacement and response speed of the valve. The results show that this optimization method can significantly improve the response speed of the spool and promote the linearity of spool displacement under a slope signal. In addition, the fluctuation of chamber pressure and spool displacement caused by the discontinuous flow of a fast switching valve is systematically analyzed. The analysis shows that increasing pulse-width modulation carrier frequency is an effective way to reduce fluctuation amplitude. The research provides a new design idea and control method for an electro-hydraulic proportional directional valve of hydraulic roof support.

In this paper, a self-tuning Robust Integral of Sign of Error (RISE)-based backstepping controller is designed for an electro-hydraulic arm system with a fourth-order system model. The RISE control...

Aiming at the tracking accuracy and hysteresis of the periodic displacement signal in electro‐hydraulic servo system, a new type of repetitive PID control strategy (RPID) was proposed. The RPID controller is based on repetitive control and PID control. By linearizing the non‐linear model and employing the Lyapunov stability theorem, the proportional value and the maximum shear frequency of the RPID controller are calculated, and the integral and differential coefficients are obtained through repeated debugging on the system. Comparison experiments of PID and RPID controllers were carried out on the experimental platform of electro‐hydraulic servo system. The results show that the error of RPID tracking is less than 0.04 mm after several cycles, which is lower than the error of PID. The tracking hysteresis finally decreases to a tolerable threshold during the tracking process with RPID controller, which greatly improves the periodic position tracking characteristics of electro‐hydraulic servo system.

Electro Hydraulic Servo Systems (EHSS) offer fast response in different industrial aspects such as heavy machines, cranes and robots. To obtain a precise piston profile and to achieve the designed speed, a Sliding Mode Controller (SMC) for the duration of piston extension and retraction is presented in this paper. The novelty lies in the development of a practical profile connecting the system supply pressure dynamics to the duration of piston extension and retraction. Based on the curve fitting technique, a quadratic profile is designed for a practical hydraulic press. The Sliding Mode Controller is employed to achieve repeatable tracking of the profile generated with guaranteed soft seating velocity, thereby increasing the lifetime of the hydraulic press. The performance of the proposed controller is compared with the baseline Proportional Integral Derivative (PID) controller with square wave as well as exponential wave tracking tests in simulation and experimentation which confirm the effectiveness of the proposed control scheme.

This article presents a composite adaptive control method to improve the position-tracking performance of an electro-hydraulic system driven by dual constant displacement pump and dual servo motor named as a novel electro-hydraulic system with unknown disturbance. A composite adaptive controller based on backstepping method is designed to estimate the uncertainties of electro-hydraulic control system, including the damping coefficient and elastic modulus. In order to release the persistent excitation condition of conventional adaptive control, which is often infeasible in practice, a prediction error based on the online historical data is used to update the estimated parameters. Furthermore, a disturbance observer is used to estimate the disturbance including the unmeasurable load force, friction and other unmodeled disturbance. The experiment results are provided and compared with other methods to verify the effectiveness of the proposed method, and the results have indicated that the proposed method has a better position-tracking performance with the convergent estimated parameters.

Variable valve actuation (VVA) technologies can provide improvements in fuel economy of spark-ignition (SI) engines by shifting valve timings or generating valve profiles that can minimize pumping loss. Electro hydraulic valve (EHV) is one of VVA technologies that is highly flexible in producing valve profiles to control charge mass without throttle. In this work, a new EHV which has a unique operating mode, namely mechanical mode, is introduced. The mechanical mode enables operation of valvetrain under circumstances of EHV malfunctions: the mechanical electro-hydraulic valvetrain (MEHV) developed in this study was capable of stable operation under various operating modes at wide ranges of oil temperatures and cam speeds with appropriate valve seating velocity and ramp duration. The MEHV is a VVA technology that can resolve issues of previous EHVs which lacked reliability under emergency conditions.

This paper discusses the role of the active anti-roll bar system in order to enhance the roll stability of cars, thereby preventing rollover phenomenon in high speed emergency situations. First, an integrated full car model is proposed including the longitudinal, lateral, vertical motions and an electro-hydraulic actuator model. In this full car model, the control signal being the input current which is supplied to the actuators to create the active torques to improve the car's stability. This is the most general model in theory to study this active roll control system and is a big step forward compared to previous related studies. The optimal LQR control method has then been used to synthesize the controller based on the integrated model with 26 degrees of freedom. The criteria used to assess the vehicle roll stability are the sprung mass roll angle and the interactive force between the wheels and the road surface. The simulation results in the frequency domain and the validation in the time domain through the CarSim software's nonlinear car model clearly show the advantages of this active system with an optimal LQR controller in preventing vehicle rollover.

The article considers the influence of electro-hydraulic pulses on the combustion of phosphorus sludge. Electric discharges in the environment of phosphorus sludge are sources of shock waves, which destroying the structure of phosphorus sludge and contribute to the intensification of the combustion process. A distinctive feature of the electro-hydraulic effect is the ability to control the parameters of pressure waves over a fairly wide range using the characteristics of the electric discharge circuit. For determine the optimal productivity and purity of the final product of the electric discharge unit’s operation mode, experiments were conducted on the effect of the discharge energy on the efficiency of the electric discharge method for extracting phosphorus from phosphorus sludge. The efficiency of the electric discharge process was estimated by the amount of phosphorus that was released after settling and expressed as a percentage of the total amount of phosphorus in a phosphorus sludge’s portion. The experiments were conducted out for sludges of different structures, with different phosphorus content and were conditionally divided into three groups: “rich” with phosphorus content — 70 %, “medium” — 50 % and “poor” — phosphorus content — 30 %.

The electro-hydraulic system is widely used in industrial production due to its high power-to-weight ratio, but the heavy-duty characteristics make the electro-hydraulic system subject to large disturbance force even if the actuator moves slightly, especially in mobile machines and multi-actuators system. Therefore, a position and velocity constraints method based on barrier Lyapunov function is proposed to guarantee the tracking error limited in a strict range to avoid the large disturbance force. Besides, the external disturbance, parameters uncertainty and modeling errors in the asymmetric cylinder electro-hydraulic systems affect the accuracy of position tracking seriously. So a high-gain disturbance observer is designed to estimate the lumped disturbance of the system, which can avoid amplification of the noise during the states measurement. In addition, dynamic surface control based on backstepping method is adopted to avoid the derivative explosion phenomenon when calculating the derivatives of virtual control inputs, which reduces the computational complexity of the system significantly. To verify the effectiveness of the proposed controller, proportional-integral controller and adaptive controller are designed to be compared with the high-gain disturbance observer–based dynamic surface controller with the backstepping method, and the comparison results show that the proposed controller has a more precise trajectory tracking performance.

Статья посвящена исследованию возможностей снижения влияния параметрических возмущений на показатели назначения корабельного артиллерийского комплекса. Предложен закон адаптивного управления слежением в аналитической форме и способ его технической реализации для снижения чувствительности следящего электрогидравлического привода артиллерийского комплекса к параметрическим возмущениям, возникающим в процессе эксплуатации и приводящих к нежелательным колебаниям объекта управления (вооружения), снижающих показатели его точности. В основе предложенного закона адаптивного лежит локальная оптимизация ошибки слежения (рассогласования) по квадратичному критерию относительно эталонного процесса с заданными свойствами. Структура регулятора, реализующая такой закон адаптивного управления, совпадает со структурой традиционного ПИД регулятора, что прямо указывает на способ его технической реализации. Введение адаптивного регулятора в контур следящего электрогидравлического привода-прототипа снижает его чувствительность к параметрическим возмущениям. При этом первоначальная структура привода существенно не меняется и не требуются дополнительные регулировки. Об этом свидетельствуют результаты компьютерного моделирования, выполненного в среде MATLAB & Simulink. The article is devoted to the study of the possibilities of reducing the influence of parametric disturbances on the indicators of the purpose of the ship's artillery complex. A law of adaptive tracking control in analytical form and a method for its technical implementation are proposed to reduce the sensitivity of the tracking electro-hydraulic drive of an artillery complex to parametric disturbances arising during operation and leading to unwanted oscillations of the control object (weapon), which reduce its accuracy. The proposed adaptive law is based on the local optimization of the tracking error (mismatch) by the quadratic criterion relative to the reference process with the given properties. The structure of the controller that implements such a law of adaptive control coincides with the structure of a traditional PID controller, which directly indicates the way of its technical implementation. The introduction of an adaptive controller into the prototype tracking electro-hydraulic drive circuit reduces its sensitivity to parametric disturbances. At the same time, the initial structure of the drive does not change significantly and additional adjustments are not required. This is evidenced by the results of computer simulations performed in MATLAB & Simulink.

A novel method combining the sliding mode control (SMC) and extended state observer (ESO) is proposed for position control of an electro‐hydraulic servo system (EHSS), which is nonlinear i...

Background: In some applications, the requirements of electro-hydraulic servo system are not only precise positioning, but also the speediness capability at which the actuator is operated. Objective: In order to enable the system to achieve rapid start and stop during the work process, reduce the vibration and impact caused by the change of the velocity, at the same time improve the positioning accuracy, and further strengthen the stability and the work efficiency of the system, it is necessary to perform the synergistic control between the position and the velocity of the electrohydraulic servo system. Methods: In order to achieve synergistic control between the position and the velocity, a control method of velocity feed-forward and position feedback is adopted. That is, based on the position control, the speed feed-forward is added to the outer loop as compensation. The position control adopts the PID controller, and the velocity control adopts the adaptive fuzzy neural network controller. At the same time, the position and velocity sensors are used for feedback, and the deviation signals between the position and the velocity obtained by superimposing the feedback are used as the final input of the control object, thereby controlling the whole system. Results: The control effect of the designed position / velocity synergistic controller is verified by simulation and experiment. The results show that the designed controller can effectively reduce the vibration and impact caused by the change of the velocity, and greatly improve the response velocity and the position accuracy of the system. Conclusion: The proposed method provides technical support for multi-objective synergistic control of the electro-hydraulic servo system, completes the requirements of multi-task operation, improves the positioning accuracy and response velocity of the electro-hydraulic servo system, and realizes the synergy between the position and the velocity. In this article, various patents have been discussed.

In this article, a rotary valve is developed to obtain accurate high-frequency sinusoidal vibration waveforms. Then, a uniaxial electro-hydraulic shaking table controlled by a set of parallel rotary valves is constructed, which can superpose the sinusoidal vibration waveforms. The non-sinusoidal vibration waveforms including triangular vibration waveform, rectangular vibration waveform, sawtooth vibration waveform and trapezoidal vibration waveform are generated by adjusting the spool rotation speed based on the Fourier series. The results show that with one rotary valve, the uniaxial electro-hydraulic shaking table can output accurate high-frequency sinusoidal vibration waveforms and the total harmonic distortion is less than 1% at high vibration frequency. Compared with the standard vibration waveform, the error of the generated vibration waveform is very small. For the rectangular vibration waveform and sawtooth vibration waveform, the error is less than 6%, and for the triangular vibration waveform and trapezoidal vibration waveform, the error is less than 3%. The impacts of the working conditions on the error of the generated vibration waveform are very small. The proposed method for the accurate high-frequency non-sinusoidal vibration waveform is very effective and can be applied in high vibration frequency and different load masses. With the increase of the supply pressure, the amplitude of the generated vibration waveforms increases, while the error changes in a rather narrow range. The amplitude can be adjusted by changing the supply pressure with almost no effect on the accuracy of the vibration waveform.

The tie rod is one of the key components affecting the steering stability and reliability in the steering system of heavy vehicles. In order to meet the heavy load steering requirements of heavy vehicles, the steering system is universally the electro-hydraulic power steering system (EHPSS). The hydraulic actuators used in the EHPSS are double hydraulic cylinders, which are connected in series and symmetrically installed in this study. The hydraulic drive system in the steering system will affect the steering mechanism of stress state, leading to the tension of the tie rod in most working conditions. The tie rod be compressed only in extremely unequal loading of dual-tires. The tie rod force model is established based on Lagrange equation and verified by the tie rod test platform. Three key parameters describing the force rule of tie rod are obtained by adopting quasi-steady state analysis method, including pump pressure, difference value and sum value of left and right tires steering resistance torque. Pump pressure is the key factor affecting the tie rod force. The higher the pump pressure is, the greater the pull force of tie rod is. The steering resistance torque will further affect the variation law of the tie rod force. In the analysis when the tire at middle position, with the increase of difference value of steering resistance torque, the tie rod force offset between loading conditions and no-load conditions increases. When the tire turns from the middle to both sides, the increase of sum value of steering resistance torque will result in the rising of tie rod force change rate. This study reveals the variation law and key parameters of the tie rod force of heavy vehicles. It can provide basis for stability and reliability design of steering system.

The Ferrari Sugar Mill tandem in Brazil is fully automated with variable speed for all the drives involved. The mills’ rollers are individually moved by electro-hydraulic drives (including the fourth roller in mill one), thus offering a great advantage to automate the mill in a very accurate way and to also measure the speed and torque in each of the rollers driven. The speeds and the torque of each roller of five four rollers mills tandem were registered continuously, providing information on the power consumed in each roller, in each mill and in the whole tandem. The laboratory results were analyzed at the same time and the power consumption in the mills against the tonnage of fibre extracted was reported. Special attention was given to the possibility of changing the speed ratio of the fourth roll in relation to the top roll and measure the torque and power consumption, looking for the additional advantages of the corresponding individual drive. The operational results of the milling section of the factory were good, considering the size, number of mills and the crushing rate. Also, the power consumption in the mills was excellent for these conditions. The advantage of using the individual drive for the fourth roller in mill number one was clearly observed during the season and the factory decided to drive all the fourth rollers individually in the near future.

In order to reduce steering energy consumption and improve steering feeling of heavy commercial vehicle, a novel electro-hydraulic compound steering system is proposed, which combines the function of electro-hydraulic power steering and electric power steering. The electro-hydraulic compound steering system dynamic model is established and the coordinated control strategy of dual actuators is proposed by analyzing the structure and dynamic characteristics of electro-hydraulic compound steering system. The genetic algorithm is used to optimize the steering assist torque distribution, and an Elman neural network predictive controller with fuzzy compensation is designed to solve the nonlinear problem of the electro-hydraulic compound system. Finally, the simulation is carried out by using Amesim/Simulink. The simulation results show that the coordinated control strategy designed in this paper enables the electro-hydraulic compound steering system significantly better than the traditional electro-hydraulic power steering system in steering feeling and energy consumption.

Electro-hydraulic water treatment has a large number of factors. We considered two factors, nitrate increase and disinfection. Theoretically this process is described due to the fact that electro-hydraulic shock in water is accompanied by x-ray and ultraviolet radiation, all this causes a chemical process. The article proposes a method for increasing of nitrates in water and decontamination by electro-hydraulic impacts. (Research purpose) The research purpose is in searching for the optimal parameters and operating modes of a universal laboratory installation for the transformation of water into a nutrient solution. (Materials and methods) The EnSURE (Hygiena) luminometer was used to measure microbiological contamination of water, and the ETHAN PH meter/ionometer was used to measure nitrates in water. (Results and discussion) The article presents the existing electrohydraulic devices and showes their shortcomings. Author made the conclusion that there is no universal installation in which it would be possible to get a double effect (activation and disinfection). The article presents a developed universal laboratory unit, which was used to perform disinfection and increase nitrates. The article presents the operation modes in which the effect is observed. The article presents the photo of the laboratory installation. (Conclusions) It was found that for economic reasons it is advisable to choose the first mode for water treatment. Author have identified an organic method for increasing nitrates in water and decontamination, which can be used in greenhouse complexes for growing vegetables and fruits. Pond water was treated for conversion to a nutrient solution by changing the amount of nitrates. It was found that the amount of nitrates increased by 0.86 milligrams per liter, which indicates that the water passed into a nutrient solution.

Electrohydraulic effect is used in various fields of industry and agriculture: for cleaning metal casting forms, cleaning pipes of power boilers, treatment of heating radiators, soil treatment and water disinfection. Existing technical means for water disinfection with high-voltage discharges are expensive, cumbersome and untransportable. Currently used installations use an operating voltage of 10-50 kilovolts, capacitors designed for a voltage of no more than 100 kilovolts, with a capacity of 0.025 microfarads. Water disinfection according to the conducted research can be carried out with a voltage of 10 kilovolts. (Research purpose) The research purpose is in developing and manufacturing a laboratory electrohydraulic installation for water disinfection, which has a technical novelty in terms of mobility and compactness for implementing a method of water disinfection at a voltage of no more than 10 kilovolts. (Materials and methods) During the research, next materials, equipment and devices were used: power supply; transformer; capacitor; forming gap; working body; shunt resistance. (Results and discussion) The principle of the electrohydraulic effect, which is a consequence of the occurrence of electrohydraulic shocks between high-voltage electrodes placed in a liquid, is the basis for the development and manufacture of the installation. Authors developed a structural diagram of a laboratory electrohydraulic unit for water disinfection. The article presents an experimental sample of a laboratory installation for water disinfection, which has a technical novelty in terms of mobility and compactness for implementing a method for water disinfection at a voltage of no more than 10 kilovolts. The installation consists of a power supply unit FA-5-1/300W, a high-voltage step-up transformer TDKS32-04, a capacitor K75-29A (16 kilovolts, 1 microfarad), forming a gap of metal balls with a diameter of 18 millimeters, a plastic working body made of ABS material, a shunt resistance of 1 kilohm. (Conclusions) They article shows the scientific and practical significance of the research results: a technical means for water disinfection, providing the possibility of conducting experimental laboratory studies of the electrohydraulic effect at a voltage of no more than 10 kilovolts.

The electro-hydraulic servo steering system is one of the core components of a heavy vehicle, and frequency response characteristics of this system are essential to guarantee the vehicle flexibility. However, it is difficult to establish frequency domain model directly for the frequency response characteristics analysis due to the strong nonlinearity of steering trapezoidal mechanism and hydraulic power system in electro-hydraulic servo steering system. This paper proposes a simplified linearization analysis method for the electro-hydraulic servo steering system. By variable substitution defining the load flow and load pressure, and linear fit between double tire angles and cylinder displacement, the original model is simplified to a frequency domain model. Based on this model, the essential frequency response characteristics and the effects of key parameters to electro-hydraulic servo steering system can be obtained. Through the sweep frequency response analysis, the linearized frequency domain model is compared with the nonlinear time domain model and the actual test system, respectively. As shown in Bode plots, the amplitude-frequency phase-frequency characteristic curves of models match well, which verifies linearization analysis method and linear frequency domain model. The key parameters affecting the system frequency domain characteristics are the valve flow gain, the area of cylinder rodless and rod chamber, and the linearization coefficient between the left and right tire angles and so on. The electro-hydraulic servo steering system bandwidth is only 7.38 rad/s (1.17 Hz). This research is helpful for the design and optimization of heavy vehicle dynamic steering system.

At the current stage of the development of means for automatic control for the formation of qualitative systems of machines, construction and road machinery, railway transport there are used electro-hydraulic devices transforming electric input signals into hydraulic output power. To carry out a generalized analysis and for the fulfillment of the preliminary synthesis of an automated hydraulic system on the whole the static and dynamic characteristics of its separate units should be obtained. In the paper there is presented a calculation of a theoretical dynamic characteristic of the electro-hydraulic nozzle-flap converter to substantiate potentialities of its inclusion as an adjusting device acting upon rods of a high-pressure fuel pump in the system of fuel feeding control of a KamAZ motor-car engine. At that the converter was considered as interconnected units: a unit of feedback. The methods of the investigation of processes in the converter are based on the fundamentals of the theory of automatic control. As it follows from the transition function diagram obtained as a result of the investigations carried out the transition time of a electro-hydraulic converter slide valve movement from a neutral position into an extreme one in the course of sending a maximum control signal to the coil does not exceed 1.1 sec, that is satisfactory for the formation of hydraulic drive control systems.

This paper proposed a structural design scheme of the hydraulic device of the electro-hydraulic controlled hitch system of a YM554A horticultural tractor with hydraulic device model, and the designed hydraulic device was simulated and tested to verify its performance. Results show that the motion of hydraulic actuator is stable with good response for tillage depth control, while the maximum lifting force of 10.62kN and the static settlement value of 13mm all meet the standard requirements. And the oil pressure changes rapidly with a large fluctuation with the plough position changed from transportation state to tillage state, but it quickly stabilizes, and as the tillage depth becomes larger, the oil pressure drops but remains basically stable with the maximum oil pressure change of 0.35MPa.

This letter proposes a novel backdrivable servovalve to implement a torque-controlled electro-hydraulic actuator. The proposed backdrivable servovalve simultaneously contains the characteristics of a flow-control servo valve (=feedback spring) and a pressure-control servovalve (=pressure feedback port). Consequently, the torque control performance of electro-hydraulic torque actuators (EHTAs), which consist of the backdrivable servovalve and rotary vane-type hydraulic actuators, can be enhanced. First, the effective torque bandwidth, which represents the region where the torque output remains constant within a 90 $^{\circ }$ phase lag, is improved. Second, torque-based control algorithms developed for electric motors are realized in a wide frequency region. Finally, although the effect of viscous friction increases, the effect of static friction is reduced. With these advantages, we achieved an enhanced EHTA with calculated torque output of −372 $\sim$ 355 Nm; this could facilitate in the development of a high-performance interactive robot system. The proposed backdrivable servovalve and enhanced EHTA were evaluated through experiments.

Electrohydraulic Forming (EHF) is a high strain rate-forming process which has potential applications in manufacturing of sheet metal parts. In EHF, the energy from a charged capacitor bank is deli...

Negative load operation is an inevitable operating condition for a completed task cycle of electro-hydraulic speed control system. In this working condition, to coordinate both tracking control and speed smooth regulation is necessary for avoiding stall. In this paper, a nonlinear coordinated control law aiming at independent regulation of inlet/outlet oil of valve-controlled electro-hydraulic speed system under sustained negative load is proposed. The overall control system can be divided into position tracking control subsystem and speed smooth control subsystem according to the function of the system operation. First, the coordinated control strategy is designed according to the requirements of speed tracking and speed smoothing. Then, for the coupling control problem existed in the system, a novel control law based on objective acceleration planning and expected back-pressure planning is presented. Furthermore, specified on the problem of uncertain random disturbance in practical applications, the extended state observer is designed, extending the summation of uncertain stochastic disturbance under sustained negative load into a new state variable. Finally, addressing the coordinated control strategy with expected back-pressure planning, we designed nonlinear decoupling control laws by using backstepping sliding mode robust control and backstepping sliding mode control based on extended state observer, respectively. The results of simulation and experiment show that the proposed nonlinear coordinated control strategy can provide the excellent coordination and robust performance for tracking control and speed smooth regulation.

The method of the synthesis and the pressure fluctuations damping calculation based on the electro-hydraulic analogy is proposed. The mathematical model describing the processes of unsteady fluid flow through the device is developed. Using the composed transfer function and its approximation, the oscillation damper parameters identification to reduce the outlet pressure pulsations in the triplex plunger pump is carried out.

In this paper, a novel nonlinear robust controller ensuring time-varying output constraints for the double-rod hydraulic servo systems in the presence of largely unknown matched and mismatched disturbances is proposed. By employing two extended state observers for each channel of the load dynamics and pressure dynamics of the considered hydraulic system, the large matched and mismatched disturbances are successfully compensated. In addition, a time-varying barrier Lyapunov function (BLF) of asymmetric type has been employed to make sure that the position output is never violated. The resulting controller is synthesized using the backstepping procedure. The stability of the whole closed-loop hydraulic system associated with the dual extended state observer (ESO)-based controller is strictly guaranteed. In theory, the proposed control strategy can not only ensure the output satisfy the preset constrained space, but also enhance the output tracking performance when the system faces various largely unknown disturbances. The effectiveness of the proposed controller has also been demonstrated via comparative simulation results.

Purpose The purpose of this paper is to design an automatic press-fit instrument to realize precision assembly and connection quality assessment of a small interference fitting parts, armature. Design/methodology/approach In this paper, an automatic press-fit instrument was developed for the technical problems of reliable clamping and positioning of the armature, automatic measurement and adjustment of the attitude and evaluation of the connection quality. To compensate for the installation error of the equipment, corresponding calibration method was proposed for each module of the instrument. Assembly strategies of axial displacement and perpendicularity were also proposed to ensure the assembly accuracy. A theoretical model was built to calculate the resistant force generated by the non-contact regions and then combined with the thick-walled cylinder theory to predict the press-fit curve. Findings The calibration method and assembly strategy proposed in this paper enable the press-fit instrument to achieve good alignment and assembly accuracy. A reasonable range of press-fit curve obtained from theoretical model can achieve the connection quality assessment. Practical implications This instrument has been used in an armature assembly project. The practical results show that this instrument can assemble the armature components with complex structures automatically, accurately, in high-efficiency and in high quality. Originality/value This paper provides a technical method to improve the assembly quality of small precision interference fitting parts and provides certain methodological guidelines for precision peg-in-hole assembly.