Proportional Pressure Valve Research Articles

Design and Analysis of New Hydrogen Oxygen Pneumatic Proportional Reducing Pressure Valve

The pneumatic proportional pressure reducing valve is the main pressure control component in the fuel cell gas supply system, which directly affects the performance of the entire fuel cell system. Based on the research background of the hydrogen oxygen fuel cell gas supply system, a set of pneumatic proportional pressure reducing valves suitable for hydrogen oxygen gas environments was designed. Through structural design and multi-parameter analysis, the structural parameter design optimization and characteristic analysis of the proportional valve were proposed. It can provide high-precision and high stability gas control capabilities for fuel cell systems, and provide support for engineering applications.

Design of Test Equipment for Hydrostatic Transducers and Hydraulic Fluids

The article refers to the proposed test equipment used to monitor the service life of hydrostatic transducers and fluids under constant or dynamic operating pressure loading. The proposed laboratory test equipment enables simultaneous testing of hydrostatic transducers and energy carriers in two hydraulic circuits and is designed to measure the flow characteristics and technical life of hydrostatic transducers with different energy carriers. The benefit of the proposed device is the possibility of simultaneous testing of the transducers as well as the performance of verification measurements of individual circuits, which was preceded by the development of a theoretical design. This includes the calculations necessary to determine the power of the drive, the cooling power as well as the definition of other parameters and elements of the hydraulic system. The design of the device was based on technical characteristics, load characteristics obtained by own measurements, and characteristics of individual hydraulic and electrohydraulic elements. On the basis of the prepared laboratory test equipment, it is possible to significantly shorten the time of operational tests and perform repeated tests under the same operational load with different types of energy carriers. The hydraulic circuit (primary or secondary) can be loaded through a proportional electrohydraulic pressure valve, which is able to simulate the load with the operational pressure curve obtained by measurement, as well as the cyclic stress, the frequency, amplitude, and rate of increase of which can be defined according to the selected methodology. A verification measurement of the flow characteristics of the used transducers was also carried out, which confirmed the correct function and design of the test laboratory equipment. The achieved results can be used in mechanical engineering for the accelerated life test of hydrostatic transducers, which are often used in mobile energy devices working in environmentally sensitive areas. The proposed laboratory test equipment will be used for testing ecological energy carriers, increasing the efficiency of energy conversion in agricultural facilities using biomass.

Mechanical design and evaluation of an actuator and a simulator for trans-tibial and trans-femoral prostheses

This study proposes a joint simulator to evaluate new prosthesis designs prior to patient trials to minimize the inconveniences encountered in prosthesis applications for amputees. Design and prototype manufacturing of a force-controlled series elastic actuator was realized. In addition, actively controlled trans-tibial and trans-femoral amputation prostheses were designed by utilizing this actuator. A pneumatic joint simulator consisting of a proportional air pressure valve was also designed and manufactured. The experimental results demonstrated that good position tracking performances and effective assistive forces under the simulated walking conditions were achieved. The developed systems have the potential to contribute to the improvement of inadequate features of passive prostheses and to the development of new assistive systems that better respond to the needs of people with orthopedic disabilities.

Fuzzy logic controller to control the active air suspension

The paper presents the practical implementation of active seat suspension used in vehicles and machinery. The test object is a passive suspension system, in which the vibro-insulating properties have been improved by using an active system controlled by a pneumatic bellows cylinder. Bellows cylinders in pneumatic drives act as single-acting cylinders - push cylinders. The filled bellows cylinder under constant pressure acts as an air spring. The volume of the air cushion changes under the pressure inside. Proportional pressure valve was used to control the bellows cylinder and non-contact relative displacement laser triangulation sensor was used to measure displacement of the seat. A PD-fuzzy controller was used for the control. The use of Fuzzy Logic Controller FLC enables the transition from a quantitative description to a qualitative process. The system structure with a designated output control function has been presented. Test results on the seat suspension vibro-insulating properties of a working machine are presented.

Characteristics of Thermally Actuated Pneumatic Proportional Pressure Valves and Their Application

Two types of pneumatic proportional pressure valves that use microelectromechanical system-based thermally actuated chips—a one-chip valve and a two-chip valve—are developed. The relative structures, unilateral driving mechanism, design considerations, control method, and experimental results are demonstrated. Under closed-loop control, the pressure curves of the two valves show good linearity; the rise time of the one-chip valve is about 50 ms and that of the two-chip valve is less than 40 ms. The experimental results reveal that the thermally actuated pneumatic pressure valves meet the general requirements of some industry applications. An actuator driven by the developed two-chip valve is introduced briefly as an application example, and the voltage–displacement and voltage–force output characteristics of the actuator are demonstrated via a test. The test results demonstrate the possibility and feasibility of realising a new type of thermally actuated actuator with a large force output (max. 400 N) and limited displacement (max. 1.8 mm). The designed thermally actuated actuator can be used as a driving device independently or as a pilot stage for other pneumatic control valves.

Simulation and Test for Electro-pneumatic Proportional Pressure Valve Based on AMESim

Simulation and Test for Electro-pneumatic Proportional Pressure Valve Based on AMESim

Design and Control of a 1-DOF Robotic Lower-Limb System Driven by Novel Single Pneumatic Artificial Muscle

This study determines the practicality and feasibility of the application of pneumatic artificial muscles (PAMs) in a pneumatic therapy robotic system. The novel mechanism consists of a single actuated pneumatic artificial muscle (single-PAM) robotic lower limb that is driven by only one PAM combined with a torsion spring. Unlike most of previous studies, which used dual-actuated pneumatic artificial muscles (dual-PAMs) to drive joints, this design aims to develop a novel single-PAM for a one degree-of-freedom (1-DOF) robotic lower-limb system with the advantage of a mechanism for developing a multi-axial therapy robotic system. The lower limb robotic assisting system uses the stretching/contraction characteristics of a single-PAM and the torsion spring designed by the mechanism to realize joint position control. The joint is driven by a single-PAM controlled by a proportional pressure valve, a designed 1-DOF lower-limb robotic system, and an experimental prototype system similar to human lower limbs are established. However, the non-linear behavior, high hysteresis, low damping and time-variant characteristics for a PAM with a torsion spring still limits its controllability. In order to control the system, a fuzzy sliding mode controller (FSMC) is used to control the path tracking for the PAM for the first time. This control method prevents approximation errors, disturbances, un-modeled dynamics and ensures positioning performance for the whole system. Consequently, from the various experimental results, the control response designed by the joint torsion spring mechanism can also obtain the control response like the design of the double-PAMs mechanism, which proves that the innovative single-PAM with torsion spring mechanism design in this study can reduce the size of the overall aid mechanism and reduce the manufacturing cost, can also improve the portability and convenience required for the wearable accessory, and is more suitable for the portable rehabilitation aid system architecture.

Dynamic Modeling of Brake in Power-Split DHT and Pressure Tracking Control with Sliding Mode Variable Structure Method

Since the mode transition performance of power-split DHT (Dedicated Hybrid Transmission) are directly influenced by torque dynamic characteristic of the brake, the brake pressure should be controlled accurately. In this paper, a dynamic model of brake and its pressure regulating system are established by considering system nonlinear characteristics and input disturbances, and a sliding mode variable structure controller is developed to track the brake pressure. First, the operation principle of DHT’s pressure regulating system is introduced. Second, the dynamic models of solenoid proportional pressure valve, electromagnetic direction switching valve and brake are established with AMESim parametric plant model. Furthermore, a sliding mode variable structure controller for tracking pressure is designed based on MATLAB/Simulink. Finally, the AMESim parametric plant model is validated by measurements, and the proposed controller are verified by AMESim and Simulink co-simulation. The results show that the system dynamics can be well characterized by the AMESim parametric plant model. The target pressure can be tracked rapidly and accurately by using sliding mode variable structure controller and the controller has better robustness.

Optimalization of a Brake Unit in Terms of Control Range

The paper deals with a study of actuator (brake cylinder) modification for generation of braking force in a brake unit. The original solution, carried out using the original brake cylinder in cooperation with the proportional pressure control valve, is sufficient in terms of correct function of the brake unit, but in terms of safety, the corresponding force sensor may be damaged in case of a control circuit proportional pressure valves defect. Another reason for the study is utilization of the total regulation range of the proportional pressure valve and improvement of the brake unit response time in case of braking force overload. Such overload results in tread or rotating rail surface damage. The article gives description of the currently implemented passive measures to increase safety against sensors damage, but also of proposed active measures to eliminate these defects by changing size and type of the brake cylinder.

Active control of multi-input hydraulic journal bearing system

Because of the advantages of high accuracy, high capacity, and low friction, the development of hydrostatic bearing for machine tool receives significant attention in the last decades. The mechanics and mechanical design of hydrostatic journal bearing with capillary restrictors has been discussed in literature. However, pragmatically, the undesired loading effects of cutting force tend to result in resonance and instability of the rotor and damage the shaft during operation. Therefore, multi-input, active flow control using state feedback design is proposed in this paper. To this purpose, the proportional pressure valves are added to the hydraulic system as active control devices, and the linearised models of the bearing and valve are discussed and identified. Simulation and experimental work is conducted to verify the proposed active control and parameter identification techniques. The results show that the unbalance responses of the rotor are reduced by the proposed state feedback controller, which is able to regulate the flow pressure effectively, thus enhancing the stability and accuracy of the hydraulic journal bearing.

Cross-coupling integral adaptive robust posture control of a pneumatic parallel platform

A pneumatic parallel platform driven by an air cylinder and three circumambient pneumatic muscles was considered. Firstly, a mathematical model of the pneumatic servo system was developed for the MIMO nonlinear model-based controller designed. The pneumatic muscles were controlled by three proportional position valves, and the air cylinder was controlled by a proportional pressure valve. As the forward kinematics of this structure had no analytical solution, the control strategy should be designed in joint space. A cross-coupling integral adaptive robust controller (CCIARC) which combined cross-coupling control strategy and traditional adaptive robust control (ARC) theory was developed by back-stepping method to accomplish trajectory tracking control of the parallel platform. The cross-coupling part of the controller stabilized the length error in joint space as well as the synchronization error, and the adaptive robust control part attenuated the adverse effects of modelling error and disturbance. The force character of the pneumatic muscles was difficult to model precisely, so the on-line recursive least square estimation (RLSE) method was employed to modify the model compensation. The projector mapping method was used to condition the RLSE algorithm to bound the parameters estimated. An integral feedback part was added to the traditional robust function to reduce the negative influence of the slow time-varying characteristic of pneumatic muscles and enhance the ability of trajectory tracking. The stability of the controller designed was proved through Laypunov’s theory. Various contrast controllers were designed to testify the newly designed components of the CCIARC. Extensive experiments were conducted to illustrate the performance of the controller.

System Modeling, Coupling Analysis, and Experimental Validation of a Proportional Pressure Valve With Pulsewidth Modulation Control

This paper presents system modeling and coupling analysis of a proportional solenoid valve (PSV) with pulsewidth modulation (PWM) control mode. The coupling analysis is adopted to reveal the internal relations among the electromagnetic, mechanical, fluid, and electrical subsystems based on the integrate proportional pressure valve mode for the PSV system. Then, a simplified and practical PWM strategy is proposed to design the PSV. The dynamic performance of each subsystem is analyzed with respect to a duty cycle set. Consequently, simulation using a commercial software is presented. It infers from the results that the valve has a fast response to the control signal and can reach a small flow area at the instantaneous moment during opening and closing operations. Finally, the analytical results of the designed PSV are validated by using experimental tests. It follows from the testing results that the established model is precise and the corresponding coupling analysis results are valuable for the performance design and optimization of PSV.

A novel hybrid control strategy for potential energy regeneration systems of hybrid hydraulic excavators

Excavators as a kind of typical construction machinery are widely used in all kinds of earthworks. Due to the low efficiency of the excavator, many enterprises and researchers have been committed to improving its efficiency. Energy regeneration system is an effective energy-saving technology, which has attracted much attention in recent years. However, the traditional energy regeneration system pays much attention to the energy saving, while the maneuverability is not fully considered. This article focuses on the maneuverability and the energy saving of the hybrid hydraulic excavator boom. A novel hybrid control method to guarantee the dynamic performance of the energy regeneration system, which is based on an electrical potential energy regeneration system, is proposed. A combined use of a torque controller for the permanent-magnet synchronous machine and a position controller for the proportional pressure valve makes the dynamic performance of the potential energy regeneration system insensitive to the influence from the direct current voltage, the capacity of the inverter as well as the cylinder speed, and achieves fast response and maximum energy regeneration simultaneously. To verify the effectiveness of the hybrid control method for the potential energy regeneration system, co-simulations are carried out in AMESim and Simulink. The results show that the dynamic performance of the potential energy regeneration system with the hybrid control method is close to a throttle-governing system and the regenerated potential energy is considerable.

Control Strategy for Hydraulic Hybrid Servo Drive System of Heavy Load Robot

A kind of compound servo drive system is designed using the characteristics of hydraulic motor large torque and servo motor high accuracy positioning. Proportional pressure valve, proportional flow valve and electromagnetic directional valve was used to control hydraulic motor for tracking servo motor drive control and to achieve servo motor control for weight load of large torque and high accuracy positioning. Pressure, speed control strategy of using PID control is proposed based on the above hydraulic tracking drive system, achieve precise control for trajectory of robot articulated arm under heavy load conditions. And according to the requirements of the pressure, flow rate and reversing in the process of compound servo drive, a torque, speed and direction of the switching control strategy is put forward. Mathematical model is established and simulated based on tracking control system. The experiments indicate: under heavy load conditions, response speed, torque and angle control accuracy of hydraulic hybrid drive system meet the requirements with this control method and torque, speed switching control strategy.

Fractional order control to the electro-hydraulic system in insulator fatigue test device

In this paper, a special composite hydraulic cylinder, which includes two pistons and three working chambers, is proposed for driving the insulator fatigue test device. In this force loading system, a servo valve and a proportional pressure valve are used to control the composite hydraulic cylinder to generate alternating force and fixed force respectively. Furthermore, the models of the electro-hydraulic system are built and its dynamic characteristic is analyzed based on the models. Considering the uncertainty of the model parameters, the fractional order proportional-integral-derivative controller is adopted to control the two valves. The Oustaloup method is used to discrete the fractional order controller and the iteration feedback tuning method is presented to tune the controller parameters. The tuning process which is independent on the system model can be done on the close loop system. Simulation and experimental results have shown that the fractional order controller is effective.

Precision Trajectory Tracking Control of a Pneumatic Cylinder and Output Stiffness Regulation

Precision motion trajectory tracking control of a single rod pneumatic cylinder driven by two proportional pressure valves is considered. Rather severe nonlinearities and uncertainties exist in the dynamic modeling of the system. In order to guarantee both the transient performance and final accuracy, a nonlinear adaptive robust controller is developed. The proposed controller comprises a sliding mode controller (SMC) and an on-line recursive least squares estimator (RLSE). The RLSE is utilized to reduce the extent of parametric uncertainties, and the SMC is adopted to attenuate the effects of parameter estimation errors, unmodelled dynamics and disturbance. Since pressure in each cylinder chamber is controlled independently, output stiffness regulation can be achieved by changing the nominal control voltage. Several experiments are conducted to test the proposed control strategy, and the results well fulfill the design requirements.

Control Architecture of a 10 DOF Lower Limbs Exoskeleton for Gait Rehabilitation

This paper describes the control architecture of a 10 DOF (Degrees of Freedom) lower limbs exoskeleton for the gait rehabilitation of patients with gait dysfunction. The system has 4 double-acting rod pneumatic actuators (two for each leg) that control the hip and knee joints. The motion of each cylinder's piston is controlled by two proportional pressure valves, connected to both cylinder chambers. The control strategy has been specifically designed in order to ensure a proper trajectory control for guiding patient's legs along a fixed reference gait pattern. An adaptive fuzzy controller which is capable of compensating for the influence of the dry friction was successfully designed, implemented and tested on an embedded real-time PC/104. In order to verify the proposed control architecture, laboratory experiments without a patient were carried out and the results are reported here and discussed.

Study and Application of a Slide Mode Control on Pneumatic Force Servo System

In this paper, a sliding mode control approach combined with the boundary saturation function approach is put forward and used in a pneumatic force servo system to achieve an exact force control. First, a comparatively accurate model of the system is obtained by using the system identification approach and an analysis is made on the time-varying nature of the model. Then, it is designed by use of the boundary saturation approach, thus overcoming the system instability caused by the non-linearity of the proportional pressure valve and the change of the temperature inside the air cylinder. Finally, the performance of the pneumatic force servo control system is simulated and a comparison is made with the PID control. Results show the feasibility and effectiveness of the approach.

DESIGN AND TEST OF PNEUMATIC SYSTEMS FOR PRODUCTION AUTOMATION

This paper deals with the teaching activity on the design and test of pneumatic and electro-pneumatic systems, which is carried out at the University of Cassino in Italy, since the academic year 1994 / 95. In particular, the design and test of a vacuum gripper and an automatic packaging machine, are proposed as examples of components and systems operating in on/off environment. Likewise, a proportional pressure valve and a robotic automatic packaging are presented as examples of components and systems operating in analogue environment for the production automation.

Study of Smooth and Accurate Position Controls of Pneumatic Artificial Muscle Actuators for Robotic Arms

This paper utilizes position errors, position error rates and payload variations as inner feedback loops for controlling the actuators of joint rotations in a pneumatic artificial muscle (PAM) driven robot. The result is an algorithm that is able to adaptively regulate input signals for the proportional pressure valve that controls the air flow to the PAM, in an attempt to better mimic the point-to-point movement of human arm. Further, the algorithm is able to utilize the angular position information from an outer feedback loop to activate/deactivate a solenoid valve for a rapid damping of the non-oscillatory motion and thereby, able to quickly and accurately bring the joints to a rest at a desired position. The proposed method appears to be effective in overcoming some of the inherent drawbacks that arise from the viscoelastic shell and air compressibility of the PAM element.