Servo Valve Research Articles

Development of a Novel Two-Dimensional(2d) Three-Way(3w) Fuel Flow Control Servo Valve with Constant Pressure Difference

Development of a Novel Two-Dimensional(2d) Three-Way(3w) Fuel Flow Control Servo Valve with Constant Pressure Difference

Simulation and experimental study on the influence of initial volume of accumulator on position control of rolling mill based on MATLAB

In order to realize high-precision control of rolling mill and improve product processing quality. Taking the accumulator in front of the servo valve in the hydraulic system of the rolling mill as the research object, this paper establishes a simulation model to analyze the influence of the initial volume of the accumulator on the accuracy of the screwdown position control system. Through changing the accumulator with different initial volume in front of the servo valve and analyzing its influence on the hydraulic screwdown position control system, a set of selection method of the initial volume of the accumulator in front of the servo valve of the hydraulic system of the rolling mill is formed. It also provides a reference basis for optimizing the hydraulic servo control system and improving the control accuracy and product processing quality.

Eddy current loss modelling for torque‐motors

A torque motor is a key component that directly influences the dynamic performance of two-dimensional (2D) cartridge servo valves. Considering the effects of eddy current, a magnetic circuit model of a torque motor is proposed, and the eddy current resistance value considering the skin effect is calculated. When the eddy current effect is ignored, the natural frequency and critical damping of a torque motor are less than the calculated values under the eddy current effect, so the eddy current influence can be assumed to increase torque motor damping, as the iron loss can be equivalent to the damping energy consumption. Test rigs were set up and experiments were conducted based on a torque motor prototype. Through a finite element simulation analysis, the eddy current effect of the armature was found to be greater than that of the yokes. The magnetic leakage coefficients of the permanent magnets were calculated, and the obtained values were compared through experiments and simulations. Both the numerical simulations and experimental results showed that the eddy current model is closer to actual working conditions than the model for which the eddy current loss was ignored.

DEVELOPMENT OF 5 DOF ROBOTIC ARM PROTOTYPE CONTROL SYSTEM IN BRACHYTHERAPY PREPARATION BASED ON ARTIFICIAL NEURAL NETWORK

Brachytherapy is a cancer treatment that uses radioactive sources with temporary or permanent implantation in cancer tissue. The theraphy uses a radioactive Ir-192 source wrapped in a stainless steel capsule with a diameter of 0.5 mm and a length of 4 mm. The Center for Radioisotopes and Radiopharmaceutical Technology applies a remote manipulator to manufacture microcapsules, which affects the accuracy and risks of the radiation received by the operator. Therefore, to solve this problem, it is necessary to design a 5 DoF robotic arm based on artificial neural networks as a radioactive source transfer tool to improve the precision and safety of operators in preparing the radioactive sources. In developing the 5 DoF robotic arm control system, the NImyRIO was employed, which can control the servo motor, relay pump and valve reality, image processing, and inverse kinematic. The inverse kinematic uses the neural network method with a forward kinematic validation. The inverse kinematic test obtains the RMSE value of 2.78932 for x, 5.05205 for y, and 12.641 for z in the inverse kinematic test of artificial neural networks. Therefore, the inverse kinematic accuracy of the artificial neural network needs to be redeveloped.

A Performance Prediction Method for a High-Precision Servo Valve Supported by Digital Twin Assembly-Commissioning

The manufacturing of a high-precision servo valve belongs to multi-variety, small-batch, and customized production modes. In the process of assembly and commissioning, various characteristic parameters are critical indicators to measure product performance. To meet the performance requirements of a high-precision servo valve, the traditional method usually relies on the test bench and manual experience for continuous trial and error commissioning, which significantly prolongs the whole assembly-commissioning cycle. Therefore, this paper proposed a performance prediction method for a high-precision servo valve supported by digital twin assembly-commissioning. Firstly, the cloud-edge computing network is deployed in the digital twin assembly-commissioning system to improve the efficiency and flexibility of data processing. Secondly, the method workflow of performance prediction is described. In order to improve the accuracy of measurement data, a data correction method based on model simulation and gross error processing is proposed. Aiming at the problem of high input dimension of the prediction model, a key assembly feature parameters (KAFPs) selection method, based on information entropy (IE), is proposed and given interpretability. Additionally, to avoid the poor prediction accuracy caused by small sample data, a performance prediction method based on TrAdaboost was utilized. Finally, the hysteresis characteristic commissioning of a high-precision servo valve is taken as an example to verify the application. The results indicate that the proposed method would enable accurate performance prediction and fast iteration of commissioning decisions.

Application of two-phase hybrid stepping motor based on three-phase inverter chopping control strategy in aircraft electric drive servo valve

With the development of multi-/all-electric technology, more and more aircraft platforms use electrically driven servo valves as the driving source to realize real-time adjustments of flow, pressure and temperature in the area network. The new generation of aircraft applies a stepper motor to drive the servo valve as the drive source, and utilizes the holding torque and open-loop control characteristics of the stepper motor when the stepper motor could not meet aircraft’s requirements of the reliability of the servo valve, the controllability of the opening and closing angle, and the environmental resistance. This paper develops a set of stepper motor drive servo valve control system. The system is mainly composed of flight tube bus, electromechanical management computer, remote actuation unit, remote interface unit and motor-driven servo valve. The stepper motor driver is integrated in the remote execution unit and is used to control the two-phase hybrid stepper motor to drive the servo valve. The topology of a three-phase inverter bridge drive is used to achieve the two-phase double four-shot drive, which saves about 25% power drive hardware. By controlling the two-phases motor, the direction and amplitude of the current one can realize micro-step control. The test and simulation result show that the system has higher control accuracy and better acceleration. The deceleration characteristics in two-phase full step and micro step working modes can expand the application of electric servo valve and improve aircraft performance.

Multi-objective optimization of high-speed on-off valve based on surrogate model for water hydraulic manipulators

Water hydraulic manipulators are suitable for remote handling maintenance task in reactors. Water hydraulic servo valves are currently used in the manipulators, but water has the characteristics of low viscosity and poor lubricity, there are inevitable leakage and wear failure. High speed on-off valve (HSV) can be used to generate proportional output and could be used to replace servo valves. In this research, a water hydraulic HSV for water hydraulic manipulators is proposed. An optimization method supported surrogate model, non-dominated sorting genetic algorithm II (NSGA-II), and AMESim simulation is built. And the effect of the HSV structure parameters on dynamic characteristic is analyzed using the global sensitivity analysis. The Pareto frontier is investigated using decision-making tools with FUZZY, LINMAP, and TOPSIS methods, the best solutions are selected by using the deviation index. The HSV prototype is fabricated, and the static and dynamic characteristics experiments of the HSV are carried out. The simulation results showed that, after optimization, the opening response time is reduced by 17%, and the closing response time is reduced 9%. The experimental results show that the opening response time and closing response time reach 5.93 ms and 4.84 ms.

Application of Step Motor Servo Control Technology in Integrated Thermal Management of Advanced Fighter System

The integrated thermal management of advanced fighter jets directly affects the combat performance of the aircraft. This paper develops a set of multi-cycle integrated thermal management control system, based on the stepper motor drive servo valve. The stepper motor control system is integrated in the aircraft Remote Execution Unit (REU). The controlled information, such as flow, pressure, temperature, is collected and combined through the Remote Interface Unit (RIU). Through the IEEE-1394 bus, feedback achieves deterministic transmission between control-action-response, and through inverse time protection, the high reliable power drive can be achieved. The open-loop vector micro-stepping driving strategy of the stepper motor is designed, simplifying software and hardware designs. The experimental results show that the strategy developed in this paper can better realize the characteristics of two-phase current sine wave, have better acceleration performance, improve the controllability of the opening and closing angle of the stepping motor servo valve, and satisfy the comprehensive thermal management of advanced fighters.

Structural Analysis and Improvement Design of Brake Pressure Valve Feedback Stage in Multivalve Parallel Brake System

The wheel brake device is one of the most widely used landing deceleration devices in modern aircraft. For large aircraft, a multivalve parallel brake system is usually used. When a brake pressure servo valve of a certain type of aircraft is debugged, the output brake pressure of the system shows obvious periodic oscillation with constant amplitude. This paper focuses on the brake pressure servo valve, which is the key component of the system. There are a large number of feedback and adjustment segments in the brake pressure servo valve, which can not only improve the control accuracy but also introduce nonlinear factors to cause system vibration. Therefore, in this paper, the feedback stage structure of the brake pressure servo valve is analyzed and improved, and a new two-stage pressure servo valve is designed to restrain the output brake pressure vibration of the system. Firstly, the structure principle of the original pressure servo valve is defined, and the function of the feedback stage is analyzed. Secondly, in view of the vibration problem caused by the original brake pressure servo valve, a new two-stage brake pressure servo valve is designed, which is the main contribution of this paper. Thirdly, the dynamics model of the proposed two-stage brake pressure servo valve is established, and the simulation model of the brake pressure servo valve-controlled cylinder system and the multivalve parallel brake servo control system is built. Finally, experiments are carried out on the experimental platform of a multivalve parallel brake system to verify that the proposed two-stage pressure servo valve can restrain the vibration of the system more effectively than the original brake pressure servo valve. And the two-stage pressure servo valve prototype is successfully applied to the actual aircraft brake control system; the system can better maintain a stable brake pressure output.

Direct compensation of the spindle rotation error with an active hydrostatic journal bearing system

Spindle rotation accuracy is important in machining process. Indirect compensation of spindle rotation error has been widely adopted in the field of machining accuracy improvement. However, there are some limitations on indirect compensation, and a little research on direct compensation can be found. This article utilizes active lubrication technology to improve the spindle rotation accuracy. Hydrostatic journal bearing with control recesses and servo valve drove by piezoelectric ceramics are adopted to compose the compensation element. The simple control strategy PID is adopted to provide control signal for servo valve. Both simulation and experiment are designed and conducted. The results show that proposed bearing system has the ability to improve the spindle rotation accuracy.

Numerical and experimental investigation of leakage behavior at null position of high-pressure electro-pneumatic servo valve

Numerical and experimental investigation of leakage behavior at null position of high-pressure electro-pneumatic servo valve

Influences of Control Parameters on Reduction of Energy Losses in Electrohydraulic Valve with Stepping Motors

In many heavy machines, the use of high force drives is required. For such tasks, electrohydraulic servo drives with proportional valves are used most often. In these valves, the proportional electromagnets are applied. If high precise control is additionally required, it is necessary to use expensive servo valves or precise stepping motors. In this paper, the application of a valve with one (or with two) stepping motors in the electrohydraulic servo drive is described. Such motors may work in a micro-step mode, which enables the precise positioning of the valve spool with low energy consumption. The control system structure that was used for positioning, consisting of such an electrohydraulic servo drive with a valve having stepping motors, is described. In the investigations, the following control parameters are considered: the number of stepping motors used, proportional gain coefficients, supply pressure, and desired step distance. The simulation model of the servo drive is proposed, enabling the investigations of energy consumption during the positioning process. In the investigations, the drive step responses are recorded and compared, taking into account the rise time and energy consumption. The overshot-free algorithm is used in the following step and tested in positioning tasks. The collected results of energy consumption of the drive during the positioning process are compared with other solutions.

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.

Timely diagnostics of hydraulic equipment in metallurgical production

Precision control of hydraulic equipment is a distinctive feature of modern hydraulic systems. With the help of special diagnostic devices, it is possible to reliably and simply monitor the operation of hydraulic equipment. Diagnostic methods can be very different. The article lists the stages and methods of checking hydraulic equipment malfunctions, as well as describes the principles of operation of diagnostic devices of well‑known world manufacturers HYDAC, MOOG, used in OJSC “BSW – Management Company of the Holding “BMC”. Schematically, the connection of the MOOG tester to the production equipment is presented when checking the servo valve in autonomous and combined mode, without resorting to dismantling the valve. Continuous monitoring of the oil purity with the help of the HYDAC FCU device allowed saving time on assessing its condition and taking fast‑acting corrective measures to clean the oil from contamination.

Development and Application of a New Triaxial Testing System for Subzero Rocks

Abstract To face the challenges of coal production today, the mechanical behaviors of rock in subzero and disturbed environments are critical in the geomechanics of coal mining and artificial freezing engineering. Disturbances significantly affect the long-term mechanical properties and nonlinear viscoelastic-plastic deformation characteristics of frozen soft rock. This article summarizes current rock triaxial test systems, which cannot concurrently solve the problems of subzero temperatures, creep, disturbance, and high sampling rates. Based on existing equipment limitations and the current research aims, an innovative, applicable, and scalable measurement/control system based on National Instruments hardware is integrated into LabVIEW to design and construct a new triaxial testing system capable of achieving both dynamic disturbances and subzero temperatures. The testing system can produce a basic environment with confining pressures up to 30 MPa, axial forces up to 500 kN, and lowest temperatures of −30°C. The system has a 51.2 kS/s sampling using 5-channel closed-loop control. By changing the transfer valve between the supercharger and the servo valve, both conventional triaxial compression and creep tests can be carried out. The triaxial creep tests are performed on frozen rock specimens under step loading and graded disturbances to analyze the creep deformation characteristics and failure modes of the specimens. The results show that at low stress levels, the disturbance load closes and reorganizes microcracks in the rock specimens, reducing the specimen deformation rate. With increasing stress levels or disturbance intensities, the specimen cracks expand rapidly, the creep rate increases, the disturbance energy stored in the rock specimen releases, and the specimens rapidly fail. Therefore, this disturbance creep phenomenon must be considered, and timely support should be provided for exposed frozen rock wall to guarantee construction safety. Moreover, the test results also verify that the design of the new testing system is reliable, feasible, and useful.

DESIGN OF HYDRAULIC ACTUATOR IN A TYPICAL AEROSPACE VEHICLE

An Aerospace Vehicle is equipped for flight both inside and outside the reasonable air. An Actuation System is quite possibly the main Systems of an Aerospace vehicle. This paper study includes itemized investigation of different controls Actuation System and Design of an average Hydraulic Actuation Systems. An actuator control framework worried about electrical, electronic or electro mechanical. Actuator control frameworks may appear as incredibly straightforward, physically worked start-and-stop stations, or complex, programmable PC frameworks. Pressure driven Actuation System contains Electro Hydraulic Actuators, Servo Valves, Feedback Sensing components, Pump Motor bundle, Hydraulic Reservoir, Accumulator, different wellbeing valves, Filters and so on. The main objective of this study involves design of Hydraulic Actuator and selection of various other components for the Actuation Systems of an Aerospace Vehicle. Plan of the framework incorporates plan of Hydraulic actuator and furthermore the Modeling and Analysis of actuator utilizing refined Software.

ОБЕСПЕЧЕНИЕ КАЧЕСТВЕННО-ТОЧНОСТНЫХ ХАРАКТЕРИСТИК ПРИ ВОССТАНОВЛЕНИИ ДЕТАЛЕЙ АВТОТРАНСПОРТА

One of the most common reasons for the failure of hydraulic drive systems for agricultural machinery is the working fluid leak in the contact points of the rubbing surfaces of hydraulic blocks. The application of composite coatings based on chromium on the contacting surfaces allows you to restore the defect in the shape of the part caused by wear, as well as reduce the friction coefficient at the contact points, which positively affects the wear resistance of the part. (Research purpose) The research purpose is in developing technologies for restoring parts of agricultural machinery with predetermined operational properties. (Materials and methods) A servo valve, widely used in various hydraulic drive systems, was used as an experimental sample. Its working surface was restored with a composite coating applied by electroplating to increase the wear resistance of the servo valve. (Results and discussion) Authors conducted a series of direct measurements under the same conditions. The article presents the de-pendence of the microhardness on the parameters of the electrolysis mode and the thickness of the applied coating using the method of least squares. The nature of changes in microhardness and residual stresses was evaluated to determine the quality of the coatings. The article presents the dependences of these indicators on various control parameters (current density, temperature, tool pressure). The equations of the regression of the main qualitative and accuracy characteristics of the parts were deter-mined using the apparatus of the theory of experimental planning. (Conclusions) The article presents the method for predicting coatings of a given quality, taking into ac-count the influence of the current density and the temperature of the electrolyte during electrolysis on the nature of the precipitation obtained. The influence of the tool pressure on the depth of deformation of the formed layers was estimated. This approach allows us to evaluate the nature of the stress distribution in the formed coating and the quality of the restored parts.

Particle motion and erosion morphology of the spool orifice in an electro-hydraulic servo valve under a small opening

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.

Built-in test technology for electro-hydraulic servo-valve amplifier

Objectives The electro-hydraulic servo valve operates in a harsh working environment but lacks integrated testability. In order to improve the usability and maintainability of electro-hydraulic servo valves, it is necessary to design a built-in test (BIT). Methods A BIT method involving the characteristics of the valve amplifier is proposed. On this basis, the implementation of BIT software/hardware and the concrete design of anti-false alarm measures are given, and a closed-loop electro-hydraulic servo system is constructed for verification. Results The verification test results show that this design method is feasible and can quickly detect faults online. Conclusions The BIT method is an effective way to reduce the maintenance cost of the electro-hydraulic servo system life cycle, giving it certain engineering application value.

Design and Development of an Embedded Controller for a Hydraulic Walking Robot WLBOT

In order to meet the requirement for the real-time of the hydraulic walking robot (WLBOT) and the stability of its movement, an embedded controller is proposed, which takes charge of multi-sensor information processing and signal output of the servo valve. The controller is capable of receiving control command and sending processed information while communicating with an embedded single board computer PCM-3365 via Control Area Network (CAN) bus at a 200 Hz frequency. In this paper, an appropriate interrupt cycle is selected and a 2 kHz high-speed control loop is run after we research the relationship between analog-to-digital converter direct memory access (ADC–DMA) interrupt cycle, data volume, and sampling rate. Significantly, the control strategy of WLBOT joint is introduced and a proportional-integral-derivative (PID) compound controller with velocity feedforward compensation (VFC) is realized. Meanwhile, the Chebyshev filtering algorithm is utilized to attenuate the vibration noise of joint signals. What’s more, an impedance controller is designed to gain better locomotion behavior and compliance in joint force control. Finally, the joint angle tracking and robot walking experiments are implemented, where the feasibility of the design and the validity of the control algorithm is verified. The results show that the PID velocity feedforward compensation controller can reduce the maximum tracking error by 39.13% and 71.31% in the knee and hip joint and the impedance control can reduce the standard deviation (SD) of the foot force by 36.06% and 72.79%.