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Modeling Simulation And Stability Of A Hydraulic Load Sensing Pump System With Investigation Of A Hard Nonlinearity In The Pump Displacement Control System
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Book Synopsis Modeling, Simulation, and Stability of a Hydraulic Load-sensing Pump System with Investigation of a Hard Nonlinearity in the Pump Displacement Control System by : Zachary Daniel Wagner
Download or read book Modeling, Simulation, and Stability of a Hydraulic Load-sensing Pump System with Investigation of a Hard Nonlinearity in the Pump Displacement Control System written by Zachary Daniel Wagner and published by . This book was released on 2014 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: Certain types of Load-Sensing (LS) pumps utilize a hydro-mechanical control system designed to regulate the pressure difference, or margin pressure, between the inlet and outlet of a flow control valve. With a constant margin pressure, predictable flow control and improved efficiency can be achieved by controlling the orifice area of the flow control valve. Instability due to limit cycles (sustained oscillations) that stem from nonlinearities within the system is a common issue related to hydraulic LS systems. In this work, the stability of the pressure control system was investigated using describing function analysis. Describing function analysis is a method used to approximate a nonlinearity within a nonlinear system and was conducted to predict the existence and stability of limit cycles that occur due to saturation nonlinearities within the mechanical components of the LS system. A combination of linear and nonlinear analysis and modeling was employed to assess the stability of a particular LS pump system. Among many nonlinearities present in the hydro-mechanical LS system, of particular interest was the saturation inherent in the actuator that is used to displace the pump swash plate and the saturation within the 3-way spool valve that permits flow to reach the actuator. This saturation nonlinearity was believed to be a problematic source for limit cycles that tend to appear in LS systems. A comprehensive nonlinear model was developed as the foundation for this research as it was used for validation in direct comparison to experimentally acquired data. The nonlinear model proved to be precise and accurate in matching to the experimental test bed response based on the data that was gathered. The acquired data was compared to the NL model simulation through a root mean squared error evaluation and frequency response analysis. The nonlinear model was then used to generate a linearized model necessary for stability analysis. The saturation nonlinearities for two separate mechanical systems were isolated from the rest of the linearized system dynamics to provide a system structure necessary for conducting describing function analysis. Analysis of model characteristics and dynamics was used to make conclusions about the stability of the system. The results of the describing function analysis demonstrated an accurate diagnosis of the stability of the system through three separate scenarios. Each scenario indicated that describing function analysis can be very useful and certainly is appropriate for predicting the stability for a high-order LS system model such as the one presented in this research. Investigation into the results also revealed the critical importance of following the fundamental assumption of describing function analysis. The linear dynamics used for the hydraulic system must satisfy the filtering hypothesis required for describing functions. A scenario in which the filtering hypothesis was violated was encountered and an adjustment of the model by removing higher frequency dynamics could allow for even more improved results in the future.
Book Synopsis Experimental Modeling of a Hydraulic Load Sensing Pump Using Neural Networks by :
Download or read book Experimental Modeling of a Hydraulic Load Sensing Pump Using Neural Networks written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The traditional method of modeling dynamics of a nonlinear hydraulic system is to develop mathematical describing equations based on "laws of nature". The development of these describing equations for a physical hydraulic system often requires that engineering intuition and a priori knowledge of the system be combined with mathematical properties of the equations. In addition, the problems of accurately measuring or defining physical parameters or coefficients have frequently restricted the interpretation of modeling results to specific operating points with very limited modeling accuracy. An alternative modeling approach is to establish or approximate mathematical relationships of a dynamic system based on observed input-output data. Neural networks have been a class of very attractive mathematical model structures that can be used to establish these mathematical relationships, because of their proven capabilities of approximating many nonlinear functions. The overall objective of the research in this study is to develop a neural network simulation package to assist designers in the simulation and configuration of hydraulic circuits. The specific objective of this thesis is to explore the capabilities of neural networks to approximate the nonlinear dynamics of a particular hydraulic component using an experimental approach. In this thesis, the use of partially recurrent neural networks with the conjugate gradient training algorithm to model a hydraulic load sensing pump was investigated. A simulation study was first conducted using "noise-free" data to examine the modeling errors in order to provide a clear insight into the mechanism of the modeling error accumulation over the transient state with a recurrent type of model structure. The established concepts and approach were then applied to experimentally model a load sensing pump. An experimental system was designed and constructed with particular attention paid to the design and generation of sufficiently rich i.
Book Synopsis Modeling and Experimental Evaluation of a Load-sensing and Pressure Compensated Hydraulic System by :
Download or read book Modeling and Experimental Evaluation of a Load-sensing and Pressure Compensated Hydraulic System written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy load equipment, such as tractors, shovels, cranes, airplanes, etc, often employ fluid power (i.e. hydraulic) systems to control their loads by way of valve adjustment in a pump-valve control configuration. Most of these systems have low energy efficiency as a consequence of pressure losses across throttle valves. Much of the energy is converted into heat energy which can have determinantal effects on component life and the surrounding environment. From an energy efficiency point of view, an ideal hydraulic system is one that does not include any throttling valve. One such circuit is made of a variable pump and motor load (pump/motor configuration). The velocity of the load is controlled by manipulating the pump displacement or by changing the rotary speed of the pump shaft. In such a system, the transient response of the load is often unsatisfactory because it is difficult to quickly and accurately manipulate the pump displacement or change shaft speed. Thus circuit design must be a compromise between the energy efficiency of the pump/motor system and the controllability of a pump/valve/motor combination. One possible compromise is to use a pump-valve configuration which reduces energy losses across the valve. One way to achieve this is by controlling the pressure drop across the valve and limiting it to a small value, independent of load pressure. Based on this idea, a type of hydraulic control system, usually called load-sensing (LS), has recently been used in the flow power area. This type of system, however, is complex and under certain operating conditions exhibits instability problems. Methods for compensating these instabilities are usually based on a trial-and-error approach. Although some research has resulted in the definition of some instability criterion, a comprehensive and verifiable approach is still lacking. This research concentrates on identifying the relationship between system parameters and instability in one particular type of LS system.
Download or read book Applied mechanics reviews written by and published by . This book was released on 1948 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Modelling, Monitoring and Diagnostic Techniques for Fluid Power Systems by : John Watton
Download or read book Modelling, Monitoring and Diagnostic Techniques for Fluid Power Systems written by John Watton and published by Springer Science & Business Media. This book was released on 2007-03-24 with total page 367 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the background theory of fluid power and indicates the range of concepts needed for a modern approach to condition monitoring and fault diagnosis. The theory is leavened by 15-years-worth of practical measurements by the author, working with major fluid power companies, and real industrial case studies. Heavily supported with examples drawn from real industrial plants – the methods in this book have been shown to work.
Book Synopsis Experimental Modeling of a Hydraulic Load Sensing Pump Using Neural Networks by :
Download or read book Experimental Modeling of a Hydraulic Load Sensing Pump Using Neural Networks written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hydraulic Power System Analysis by : Arthur Akers
Download or read book Hydraulic Power System Analysis written by Arthur Akers and published by CRC Press. This book was released on 2006-04-17 with total page 401 pages. Available in PDF, EPUB and Kindle. Book excerpt: The excitement and the glitz of mechatronics has shifted the engineering community's attention away from fluid power systems in recent years. However, fluid power still remains advantageous in many applications compared to electrical or mechanical power transmission methods. Designers are left with few practical resources to help in the design and
Book Synopsis Modern Control Design for a Variable Displacement Hydraulic Pump by : Patrick T. Dean
Download or read book Modern Control Design for a Variable Displacement Hydraulic Pump written by Patrick T. Dean and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work modern control methods are used to design and analyze control methods for a variable-displacement hydraulic pump. More accurate uncertainty descriptions are derived by using a structured uncertainty model as opposed to an unstructured uncertainty model. The system studied includes one variable-displacement swash-plate hydraulic pump with a constant engine speed model. The input to the system is the current actuating the control valve position, while the system output is the discharge pressure of the pump. The established PID controller design lacked robustness, encouraging design of a two degrees-of-freedom control scheme. Frequency domain tests show robustness improvement over the classical PID control scheme. Time domain results show similar performance from both the PID controlled system and the two degrees-of-freedom controlled system. Time domain tests also show improved robustness to parametric variation from the modern control method, while system responses to large disturbances are similar among both the classical and modern control schemes.
Book Synopsis Fluid Power Pumps and the Electrification by : Samuel Kärnell
Download or read book Fluid Power Pumps and the Electrification written by Samuel Kärnell and published by Linköping University Electronic Press. This book was released on 2020-05-25 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: More and more vehicles are being electrified. Mobile working machines and heavy trucks are not excluded, and these machines are often hydraulically intense. Electrification entails new requirements for the hydraulic system and its components, and these requirements must be taken into consideration. Hydraulic systems have looked similar for a long time, but now there is an opportunity to advance. Many things change when a diesel engine is replaced with an electric motor. For example, variable-speed control becomes more relevant, electric regeneration becomes possible, and the use of multiple prime movers becomes an attractive alternative. The noise from the hydraulic system will also be more noticeable when the diesel engine is gone. Furthermore, the introduction of batteries to the system makes the energy more valuable, since batteries are heavy and costly compared to a diesel tank. Therefore, it is commercially viable to invest in the hydraulic system. This thesis revolves around the heart of the hydraulic system, that also is the root of all evil. That is the pump. Traditionally, a pump has had either a fixed displacement or a continuously variable displacement. Here, the focus is on something in between, namely a pump with discrete displacement. The idea of discrete displacement is far from unique, but has not been investigated in detail in combination with variable speed before. In this thesis, a novel design for a quiet pump with discrete displacement is presented and analysed. The results show that discrete displacement is relevant from an energy perspective for machines working extensively at high pressure levels and with low flow rates, and that a few discrete values are enough to make a significant difference. However, for other cycles, the possible energy gains are very limited, but the discrete displacement can be a valuable feature if downsizing the electric machine is of interest.
Book Synopsis Pump Systems Assessment Professional (PSAP) Certification Study Guide by : Hydraulic Institute
Download or read book Pump Systems Assessment Professional (PSAP) Certification Study Guide written by Hydraulic Institute and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Hydraulic Servo-systems by : Mohieddine Jelali
Download or read book Hydraulic Servo-systems written by Mohieddine Jelali and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 380 pages. Available in PDF, EPUB and Kindle. Book excerpt: This up-to-date book details the basic concepts of many recent developments of nonlinear identification and nonlinear control, and their application to hydraulic servo-systems. It is very application-oriented and provides the reader with detailed working procedures and hints for implementation routines and software tools.
Book Synopsis Stability Analysis and Design of Servo-hydraulic Systems by : Amit Shukla
Download or read book Stability Analysis and Design of Servo-hydraulic Systems written by Amit Shukla and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Design for robust stability is one of the most important issues in nonlinear systems theory. The validity of linear system design in a small neighborhood is not a sufficient criterion for systems that undergo parametric variations and have strong nonlinear characteristics. With rapid growth in the systems theory, the design of nonlinear systems using bifurcation theory-based procedures has been one of the key developments. Servo-hydraulic systems are one of the most commonly used actuation and control devices, due to their force to weight ratio. They also are highly nonlinear in nature and hence provide considerable difficulty in the design and analysis of these systems and their control algorithms. The goal of this dissertation is to tackle some of the issues of the nonlinear systems theory with applications to servo-hydraulic systems. The use of bifurcation theory for the design and analysis of a nonlinear system is illustrated, and a detailed investigation into the dynamics associated with the servo-hydraulic systems is done. Further, the model decomposition/reduction strategy for parametric study in the nonlinear system is suggested. The idea of control-induced bifurcation is introduced and explained in light of servo-hydraulic systems. The servo-hydraulic system nonlinearities are explained and their effects on the robust stability are highlighted. This numerical work is also complemented with the experimental results on the servo-hydraulic circuits. This general procedure for robust stability design and control design, under the influence of nonlinearities, presented in this work can be used for any nonlinear system. The limitations of bifurcation theory based tools are also highlighted.
Book Synopsis Simulation of Fluid Power Systems with LMS AMESiM by : Nicolae Vasiliu
Download or read book Simulation of Fluid Power Systems with LMS AMESiM written by Nicolae Vasiliu and published by CRC Press. This book was released on 2016-06-15 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book illustrates use of numerical simulations for modeling and design of hydraulic components of complex systems using AMESim. The book is divided in six parts: hydrostatic transmissions, electro hydraulic servo valves, hydraulic servomechanisms for aerospace engineering, speed governors for power machines, fuel injection systems, and automotive servo systems.
Book Synopsis Modeling and Experimental Evaluation of a Load-sensing and Pressure Compensated Hydraulic System by :
Download or read book Modeling and Experimental Evaluation of a Load-sensing and Pressure Compensated Hydraulic System written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Heavy load equipment, such as tractors, shovels, cranes, airplanes, etc, often employ fluid power (i.e. hydraulic) systems to control their loads by way of valve adjustment in a pump-valve control configuration. Most of these systems have low energy efficiency as a consequence of pressure losses across throttle valves. Much of the energy is converted into heat energy which can have determinantal effects on component life and the surrounding environment. From an energy efficiency point of view, an ideal hydraulic system is one that does not include any throttling valve. One such circuit is made of a variable pump and motor load (pump/motor configuration). The velocity of the load is controlled by manipulating the pump displacement or by changing the rotary speed of the pump shaft. In such a system, the transient response of the load is often unsatisfactory because it is difficult to quickly and accurately manipulate the pump displacement or change shaft speed. Thus circuit design must be a compromise between the energy efficiency of the pump/motor system and the controllability of a pump/valve/motor combination. One possible compromise is to use a pump-valve configuration which reduces energy losses across the valve. One way to achieve this is by controlling the pressure drop across the valve and limiting it to a small value, independent of load pressure. Based on this idea, a type of hydraulic control system, usually called load-sensing (LS), has recently been used in the flow power area. This type of system, however, is complex and under certain operating conditions exhibits instability problems. Methods for compensating these instabilities are usually based on a trial-and-error approach. Although some research has resulted in the definition of some instability criterion, a comprehensive and verifiable approach is still lacking. This research concentrates on identifying the relationship between system parameters and instability in one particular type of LS system.
Book Synopsis Mechatronics 2019: Recent Advances Towards Industry 4.0 by : Roman Szewczyk
Download or read book Mechatronics 2019: Recent Advances Towards Industry 4.0 written by Roman Szewczyk and published by Springer Nature. This book was released on 2019-08-28 with total page 515 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gathers papers presented at Mechatronics 2019, an international conference held in Warsaw, Poland, from September 16 to 18, 2019. The contributions discuss the numerous, multidisciplinary technological advances in the field of applied mechatronics that the emerging Industry 4.0 has already yielded. Each chapter presents a particular example of interdisciplinary theoretical knowledge, numerical modelling and simulation, or the application of artificial intelligence techniques. Further, the papers show how both software and physical devices can be incorporated into mechatronic systems to increase production efficiency and resource savings. The results and guidelines presented here will benefit both scientists and engineers looking for solutions to specific industrial and research problems.
Book Synopsis Optimum Design and Control of Hydraulic Systems Driven by Swash Plate Pumps Using Vibration Based Diagnosis by : M. Molham Hasan Chikh Al Souk
Download or read book Optimum Design and Control of Hydraulic Systems Driven by Swash Plate Pumps Using Vibration Based Diagnosis written by M. Molham Hasan Chikh Al Souk and published by . This book was released on 2008 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Swash plate pumps are widely used to drive hydraulic systems, especially because they offer high specific power. In order to improve their performance and make them more reliable, it is necessary to reduce the flow fluctuations, incorporate a control system that is more responsive, and minimize vibration levels. Furthermore, the flow should be controlled according to load requirements and pipe response at the design level. Moreover, there is a need to monitor the health of the system by analysing its vibration signatures. A novel port plate design is used with a pair of deep silencing grooves on the edges of delivery and suction ports, which reduces the flow fluctuations and improves the pump output. In addition to the load information, the pipe dynamics are also used as a control input. Hence, pipe instabilities with different boundary conditions are studied, where simple, accurate and comprehensive expressions to describe the pipe instabilities are produced, solved, and plotted. In swash plate pumps, the control unit changes the pump output according to the load requirements. The current pump design is equipped with a double negative feedback strategy. The inner loop controls the spool position, and the outer loop controls the swash plate angle. Since this design has a high rise time, it was suggested to equip the pump with a single feedback PD controller. Although this reduced the rise time, it introduced high levels of vibration. The present research proposes a new control strategy with a single feedback PID controller that minimizes vibration levels. Results are obtained experimentally. The control strategy is generalized to control the pump flow according to load requirements and pipe vibration levels. A compensation factor is introduced to moderate the negative impact of the pipe vibrations, and to generate a new set value for the inclination angle. For timely detection of faults, the application of wavelet analysis to detect different defects is examined. Some defects are produced, such as pipe flutter, pump dynamic instability, and voltage unbalance in the driving electric motor. Continuous wavelet and discrete wavelet analyses are used to analyze the vibration signature by using Debauches' mother wavelet. The data is collected experimentally. The results show that wavelet analysis is very efficient at identifying defects in the pipe or pump. The results are discussed and appropriate conclusions are drawn based on the present research. Suggestions for future extensions of the research are proposed.
Book Synopsis Modeling and Experimental Evaluation of a Load-Sensing and Pressure Compensated Hydraulic System by : Duqiang Wu
Download or read book Modeling and Experimental Evaluation of a Load-Sensing and Pressure Compensated Hydraulic System written by Duqiang Wu and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
