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.
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•Research on flow characteristics of proportional flow control valve.•Modeling, simulation in MATLAB/Simulink using parameter estimation technique.•Unified model of proportional control valve has been developed.•The simulation results of electro-hydraulic hitch control have been validated with actual test results.•Unified model creates new interest and helps in non‒linear control design and optimization.
The four-way proportional directional control valve has been widely used as the main stage spring constant for the two-stage proportional control valve (PDV). Since a tradeoff should be made between ...manufacturing costs and static performance, two symmetry dead-zones are introduced in the main stage spring constant: the center dead-zone caused by the center floating position and the intermediate dead-zone caused by the intermediate position. Though the intermediate dead-zone is much smaller than the center dead-zone, it has significant effect on the dynamic position tracking performance. In this paper, the cascade dead-zones problem in a typical two-stage PDV is analyzed and a cascade dead-zones model is proposed for the main stage spring constant. Then, a cascade dead-zones inverse method is improved with gain estimation and dead-zone detection to compensate the dead-zone nonlinearity. Finally, a digital controller is designed for verification. The comparative experimental results indicate that it is effective to reduce the large position tracking error when the proposed method is applied.
•A cascade dead-zones problem in the proportional control valve is presented.•Both the intermediate dead-zone and the center dead-zone are considered.•An improved feedback control with cascade dead-zones inverse is proposed.•The proposed method improves the dynamic tracking performance successfully.
Linear proportional solenoid (LPS) is widely applied in different linear motion control systems as the electromagnetic actuator since its high reliability and low cost. LPS is difficult to optimize ...by changing a single variable due to amounts of structural design parameters, and each design parameter has a nonlinear relationship with the static electromagnetic force. This paper aims to improve LPS’s push force and response performance through magnetostatic finite element analysis (FEA) by ANSYS MAXWELL. This study compares FEA 2D model, 3D model and measurement results underrated coil current to verify the accuracy of FEA 2D model. In order to reveal the nonlinear relationship between shape design parameters and electromagnet design objectives, this study compares the influence degree of each variable on each design objective by conventional type LPS 2D FEA model. And for the purpose of improving LPS’s push force and response performance, a multi-objective optimization method has been proposed in this study based on genetic algorithm (GA) and magnetostatic FEA 2D model for optimizing the shape design parameters. All the study results were validated in both static conditions and dynamic conditions. The comparison between manufactured optimal type and conventional type results shows that the static push force in working stroke is improved 30.1%, displacement step response rise time is reduced 5.2% and 43.4%, and force step response rise time is reduced 20.5% and 44.6% with different return spring stiffness. Above all, LPS static and dynamic performance has been improved directly and the validation of proposed optimization method is verified in this paper.
The authors present a simplified mathematical model that describes the functioning of a pneumatic proportional control valve, together with the simulation diagrams obtained after its implementation ...using MATLAB-SIMULINK. Simulation diagrams matched the available experimental characteristics, recommending the elaborated model for the theoretical study of such equipments.
In the field of fully mechanized coal mining equipment, the hydraulic valve used in the hydraulic support is an on/off directional valve. There are many problems caused by the valve such as large ...pressure shock and discontinuous flow control. Therefore, a novel two-position three-way hydraulic proportional valve suitable for high-pressure and large-flow conditions is proposed to overcome the above problems. The novel valve utilizes a two-stage structure and the displacement follow-up principle is adopted between the pilot stage and the main stage to meet proportional control. In this paper, a simulation model of the novel proportional valve was established after a simplified analysis of the structural principle. Its reliability and the feasibility of the design were verified by the test results under different working conditions. Then, the step response characteristics of the proportional valve under different strokes were predicted and analyzed. Nonlinear characteristics were presented, and the closing time was shorter than the opening time because of the influence of nonlinear flow force. Under different ramp signals, the displacement of the main inlet spool was always approximately equal to the displacement of the pilot stage. Then, the motion relationship between the pilot stage and the main stage was studied, and the influence of the structural parameters on the stability was analyzed.
The output feedback signal of the electro-hydraulic valve system (EHVS) affects the activation of its right or left envelope function; thus, even weak measurement noise can cause high-frequency ...switching between the two envelope functions, leading to chattering in the control input. Consequently, feedforward and feedback controllers in a cascaded configuration generate undesirable chattering in the output signal. We propose a practical and reliable control approach for an EHVS actuated by a proportional control valve. The proposed controller has a parallel structure comprising an inverse generalized Prandtl–Ishlinskii (P–I) model-based feedforward controller, with both hydraulic dead-zone and flow saturation limits, for compensating asymmetric hysteretic behavior. Further, the proposed controller comprises a robust proportional-integral-derivative (PID) feedback controller for achieving robustness against disturbances and noises. The proposed parallel structure is independent of the output feedback of the EHVS. Moreover, the proposed robust PID feedback controller guarantees EHVS stability by precisely selecting the cutoff frequency for the sensitivity and complementary sensitivity functions based on the amplitude spectrum of the inverse-model-based feedforward compensation error. The results verify the high reliability of the proposed EHVS control scheme for the precise control of an EHVS actuated by a proportional control valve in practice.
微粒子励振型流量制御弁による油圧制御 浮田, 貴宏; 鈴森, 康一; 難波江, 裕之 ...
Transaction of the Japan Fluid Power System Society,
2016, Letnik:
47, Številka:
6
Journal Article
Odprti dostop
In this paper, we report on hydraulic characteristics of the particle excitation control valve, which was originally developed for a flow rate control of pneumatic actuators. The orifices are opened ...and closed with particles excited by the vibration of the orifice plate and the fluid force. This results in more simple and compact structure, and higher flow rate-to-weight ratio than conventional pneumatic valves. Because the traditional hydraulic valves are bulky and heavy, the purpose of this study is the development of a small and lightweight hydraulic valve by applying the working principle of this particle excitation valve to hydraulics. We have focused on two characteristics affected by changing the working fluid from air to oil. One is the vibration of the orifice plate, and the other is the movement of the particles. As a result, it is found that the inertia of the working fluid reduces the vibration velocity of the orifice plate to 24%, and the viscosity of the working fluid raises the operating voltage of the valve to 167% by the influence on the movement of the particles. In addition, when silicone oils are used as working fluid, whose kinematic viscosity values are 1mm2/s, 2mm2/s, and 3mm2/s, maximum volumetric flow rate of the prototype valve are 891ml/min, 887ml/min, and 838ml/min, respectively. These experimental results indicate the potential of the proposed valve for hydraulics.
In this paper, we report on hydraulic characteristics of the particle excitation control valve, which was originally developed for a flow rate control of pneumatic actuators. The orifices are opened ...and closed with particles excited by the vibration of the orifice plate and the fluid force. This results in more simple and compact structure, and higher flow rate-to-weight ratio than conventional pneumatic valves. Because the traditional hydraulic valves are bulky and heavy, the purpose of this study is the development of a small and lightweight hydraulic valve by applying the working principle of this particle excitation valve to hydraulics. We have focused on two characteristics affected by changing the working fluid from air to oil. One is the vibration of the orifice plate, and the other is the movement of the particles. As a result, it is found that the inertia of the working fluid reduces the vibration velocity of the orifice plate to 24%, and the viscosity of the working fluid raises the operating voltage of the valve to 167% by the influence on the movement of the particles. In addition, when silicone oils are used as working fluid, whose kinematic viscosity values are 1mm2/s, 2mm2/s, and 3mm2/s, maximum volumetric flow rate of the prototype valve are 891ml/min, 887ml/min, and 838ml/min, respectively. These experimental results indicate the potential of the proposed valve for hydraulics.
The proportional flow control valve is not only one of the key competent of vane damp,but also the execution unit of shock absorber damping force's regulation .The proportional flow control valves ...self-designed will combine the structural design of proportional control valve and crate CFD model . The thesis analyzes its distribution of flow field by CFD and acquires experimental validation .It analyzes dynamic characteristics and determine the relationship of flow and opening and drive current. The proportional control valve test verifies the correctness, finally. It is basis for analyzing of damping characteristics about vane damp, which can be used other proportional control valve CFD study.
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