Experimental Comparisons of the Control Solutions for Pneumatic Servo Actuators (original) (raw)
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The Influence of the Supply Line on the Performance of a Pneumatic Position Servo System
Proceedings of the JFPS International Symposium on Fluid Power, 1999
The basic characteristics of pneumatic cylinder drives are remarkably low natural frequency and fairly low damping. The main purpose when designing a controller for a demanding servo application is to find out a good and practical method to increase system damping. One of the most effective ways to increase the damping of a cylinder drive is to use a suitable controller. The most common and successful controller is so-called State controller. A state controller has three cascade loops. The total gain of each loop contains also the flow gain of a servo valve. Typical supply pressure in an industrial application is about 7 bar (abs.). Since the tuning of a demanding position servo is often quite critical, the fluctuating of the supply pressure might influence the performance of the system. This paper deals with the influence of the supply pressure on the positioning accuracy and the dynamic behaviour of a pneumatic position servo system. The influence of the size of normal pressure reducing valve (a pressure control valve) on the performance of a position servo system is studied and experimental results are presented. Also the effect of the amount of extra volume between the pressure control valve/filter and the servo valve is studied and experimental results are shown.
Nonlinear Mathematical Modeling in Pneumatic Servo Position Applications
Mathematical Problems in Engineering, 2011
This paper addresses a new methodology for servo pneumatic actuators mathematical modeling and selection from the dynamic behavior study in engineering applications. The pneumatic actuator is very common in industrial application because it has the following advantages: its maintenance is easy and simple, with relatively low cost, self-cooling properties, good power density power/dimension rate , fast acting with high accelerations, and installation flexibility. The proposed fifth-order nonlinear mathematical model represents the main characteristics of this nonlinear dynamic system, as servo valve dead zone, air flow-pressure relationship through valve orifice, air compressibility, and friction effects between contact surfaces in actuator seals. Simulation results show the dynamic performance for different pneumatic cylinders in order to see which features contribute to a better behavior of the system. The knowledge of this behavior allows an appropriate choice of pneumatic actuator, mainly contributing to the success of their precise control in several applications.
Modeling pneumatic position servo realized with commercial components
Proceedings of the JFPS International Symposium on Fluid Power, 1993
The use of pneumatic position servos is growing due to increasing supply of pneumatic servo components onto the market. For designer who tries to apply pneumatic servos there is only little detailed information available. In this paper the basic model for electropneumatic position servo is presented. In the model only basic knowledge of pneumatics and normal commercial information of pneumatic components are needed. Verified simulation results for open and closed loop systems are presented.
Robust QFT controller design for positioning a pneumatic servo actuator
Proceedings of the 2nd …, 2009
The pneumatic servo actuator represents the main force control operator in many industrial applications, where its static and dynamic characteristics play an important role in the overall behavior of the control system. In this paper ∞ H robust controller is designed for a typical industrial pneumatic actuator controlled by a jet pipe valve. The pneumatic system nonlinearity and system parameters uncertainty are the main problems in the design of a desired controller for this plant. To design a controller a linear model of the plant at certain operating point is derived. The structured (parametric) perturbations in the plant coefficients is taken into account. The ∞ H control techniques ensure robust performance and stability for the pneumatic servo actuator system. Simulation results are presented to verify the objectives of the controller.
Position feedback dynamic surface control for pneumatic actuator position servo system
Systems Science & Control Engineering, 2018
Pneumatic servo system is widely utilized in many industries, which has huge potential to replace hydraulic and electromechanical system due to its low-cost, high power quality ratio and quick response. There have been considerable control methods proposed to complete pneumatic position servo control. However, these methods still have some inevitable problems which remain to be settled. In this paper, a position feedback dynamic surface control is applied to the pneumatic system based on our pneumatic actuator model in order to provide a new idea for pneumatic position control. Considering model uncertainties, external force disturbance and noise interference, a modified dynamic surface controller is developed to overcome their negative effects. Besides, the stability of the pneumatic system with the modified controller is proved by Lyapunov's stability theorem. Moreover, the results of simulation and pneumatic experiment also verify that the dynamic surface controller is more advantageous than the traditional PID controller in pneumatic position servo control.
The role of pressure sensors in the servo control of pneumatic actuators
2003
Pneumatic servo actuators are characterized by highly nonlinear dynamics, and as such are well suited to the use of nonlinear control methods requiring measurement of the full state, such as sliding mode control. The requirement of pressure measurement, however, is particularly burdensome, due in large part to the high cost of pressure sensors relative to other components of the servo system. Since the cylinder pressures are states of the dynamic system, the possibility exists of eliminating the pressure sensors in lieu of a nonlinear observer. Through the construction and rank test of a nonlinear observability matrix, it is shown that significant singular points exist in the system that, for most practical purposes, renders impractical the use of a nonlinear observer to reconstruct pressure states. 0-7803-7896-2/03/$17.00 02003 IEEE
The issue of energy saving nowadays is very crucial. Pneumatic systems, constituting an important segment of almost every industry, represent large energy consumers. Also, a significant problem with servo pneumatic actuators is achieving accuracy in positioning. The higher the positioning accuracy, the higher the compressed air consumption is. This paper presents a new solution of the positioning control algorithm which unifies digital control of variable structure and sliding working mode and inter chamber cross-flow. The experiments demonstrated that this control algorithm provides a satisfactory positioning accuracy and robustness of the system, simultaneously reducing compressed air consumption by as much as 29.5%.
A review of pneumatic actuators (modeling and control)
Australian Journal of Basic …, 2009
The pneumatic actuator represents the main force control operator in many industrial applications, where its static and dynamic characteristics play an important role in the overall behavior of the control system. Therefore improving the dynamic behavior of the pneumatic actuator is of prime interest to control system designers. This paper is a review of literature that related of the pneumatic actuator systems. In particular, the innovations in different control strategies applied to pneumatic actuators along with the modeling, controlling and simulation techniques developed for different applications of pneumatic actuators are reviewed. The review concentrates also on the analysis, investigation, performance, practical constraints, nonlinearities, uncertainties and the new applications of the pneumatic actuators.
POSITIONING SYSTEM OF A PNEUMATIC ACTUATOR DRIVEN BY PROPORTIONAL PRESSURE REGULATOR VALVES
Proceedings of the 4th Workshop on Innovative Engineering For Fluid Power – WIEFP 2018, 2018
This paper presents a positioning system of a linear double acting pneumatic cylinder commanded by two proportional pressure regulator valves. The advantages presented by pneumatic systems make this technology reason for constant research in the scientific field. But, the nonlinearities related to the use of compressed air and the involved frictions in the movement make the control complex. In many researches about this subject, the authors adopted proportional valves to control the air mass flow directed to the rear and front chambers of the pneumatic cylinder. In the present research, the proportional valves controlled the air pressure instead of air mass flow. The pneumatic cylinder was equipped with an internal linear resistive transducer and the proportional pressure regulator valves were set to work in double loop mode, monitoring and controlling the input and output signals of the process. Each valve was equipped with an onboard proportional integral (PI) controller which were tuned according to the second technique proposed by Ziegler-Nichols. To make possible the execution of simulations, mathematical models were developed taking into account the piston dynamics, the compressed air behavior inside the front and rear chambers, the static and dynamic frictions and the valves dynamics. To validate the mathematical model proposed, comparisons between the experimental data, collected from a prototype connected to the software Labview, and the computational simulations results, that were performed in the software Matlab / Simulink, were done. The results obtained from the experimental data returned a maximum position error of 4,48mm for positive steps inputs, which was considered satisfactory for industrial applications. The comparison between simulated and experimental responses shows that the mathematical model presents a satisfactory approximation from the real system, although the experimental results have a faster stabilization time than the simulation, the transient response and the errors were similar.
Review on controller design in pneumatic actuator drive system
TELKOMNIKA Telecommunication Computing Electronics and Control, 2020
A pneumatic actuator is a device that converts compressed air into mechanical energy to perform varieties of work. It exhibits high nonlinearities due to high friction forces, compressibility of air and dead band of the spool movement which is difficult to manage and requires an appropriate controller for better performance. The purpose of this study is to review the controller design of pneumatic actuator recommended by previous researchers from the past years. Initially, the basic views of the pneumatic will be presented in terms of introduction to the pneumatic actuator and its applications in industries. At the end of this review, discussions on the design of the controllers will be concluded and further research will be proposed along with the improvement of control strategies in the pneumatic actuator systems.