47 research outputs found
De-Centralized and Centralized Control for Realistic EMS Maglev Systems
A comparative study of de-centralized and centralized controllers when used with real EMS Maglev Systems is introduced. This comparison is divided into two parts. Part I is concerned with numerical simulation and experimental testing on a two ton six-magnet EMS Maglev vehicle. Levitation and lateral control with these controllers individually and when including flux feedback control in combination with these controllers to enhance stability are introduced. The centralized controller is better than the de-centralized one when the system is exposed to a lateral disturbing force such as wind gusts. The flux feedback control when combined with de-centralized or centralized controllers does improve the stability and is more resistant and robust with respect to the air gap variations. Part II is concerned with the study of Maglev vehicle-girder dynamic interaction system and the comparison between these two controllers on this typical system based on performance and ride quality achieved. Numerical simulations of the ODU EMS Maglev vehicle interacting with girder are conducted with these two different controllers. The de-centralized and centralized control for EMS Maglev systems that interact with a flexible girder provides similar ride quality
Third International Symposium on Magnetic Suspension Technology
In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Third International Symposium on Magnetic Suspension Technology was held at the Holiday Inn Capital Plaza in Tallahassee, Florida on 13-15 Dec. 1995. The symposium included 19 sessions in which a total of 55 papers were presented. The technical sessions covered the areas of bearings, superconductivity, vibration isolation, maglev, controls, space applications, general applications, bearing/actuator design, modeling, precision applications, electromagnetic launch and hypersonic maglev, applications of superconductivity, and sensors
Control of maglev vehicles with aerodynamic and guideway disturbances
A modeling, analysis, and control design methodology is presented for maglev vehicle ride quality performance improvement as measured by the Pepler Index. Ride quality enhancement is considered through active control of secondary suspension elements and active aerodynamic surfaces mounted on the train. To analyze and quantify the benefits of active control, the authors have developed a five degree-of-freedom lumped parameter model suitable for describing a large class of maglev vehicles, including both channel and box-beam guideway configurations. Elements of this modeling capability have been recently employed in studies sponsored by the U.S. Department of Transportation (DOT). A perturbation analysis about an operating point, defined by vehicle and average crosswind velocities, yields a suitable linearized state space model for multivariable control system analysis and synthesis. Neglecting passenger compartment noise, the ride quality as quantified by the Pepler Index is readily computed from the system states. A statistical analysis is performed by modeling the crosswind disturbances and guideway variations as filtered white noise, whereby the Pepler Index is established in closed form through the solution to a matrix Lyapunov equation. Data is presented which indicates the anticipated ride quality achieved through various closed-loop control arrangements
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A review of dynamic characteristics of magnetically levitated vehicle systems
The dynamic response of magnetically levitated (maglev) ground transportation systems has important consequences for safety and ride quality, guideway design, and system costs. Ride quality is determined by vehicle response and by environmental factors such as humidity and noise. The dynamic response of the vehicles is the key element in determining ride quality, while vehicle stability is an important safety-related element. To design a guideway that provides acceptable ride quality in the stable region, vehicle dynamics must be understood. Furthermore, the trade-off between guideway smoothness and levitation and control systems must be considered if maglev systems are to be economically feasible. The link between the guideway and the other maglev components is vehicle dynamics. For a commercial maglev system, vehicle dynamics must be analyzed and tested in detail. This report, which reviews various aspects of the dynamic characteristics, experiments and analysis, and design guidelines for maglev systems, discusses vehicle stability, motion dependent magnetic force components, guideway characteristics, vehicle/ guideway interaction, ride quality, suspension control laws, aerodynamic loads and other excitations, and research needs
Vibration Isolation of a Locomotive Mounted Energy Storage Flywheel
Utilizing flywheels to store and reuse energy from regenerative braking on
locomotives is a new technology being developed in the Vibration Control and
Electromechanics Lab at Texas A&M. This thesis focuses on the motion analysis of a
locomotive mounted energy storage flywheel system for a variety of support motion
inputs. Two input cases, sinusoidal floor input and ramp input, are analyzed in different
sections. Simulation results and methods of ensuring the operating success of the
flywheel system are provided at the end of each section.
Section 1 introduces the problem and method being used to study the vibration
under different circumstances. Section 2 analyzes the response of the flywheel system to
sinusoidal floor input given by Ahmadian and Venezia 2000. Natural frequency and
transmissibility of the system are utilized to explain the simulation results carried out in
the frequency domain. It is found that the motion differences between flywheels(rotors)
and magnetic bearings(stators) are guaranteed to be small. Section 3 emulates the
locomotive traversing a bump with 1:150 slope. Simulation shows that catcher(backup)
bearings are needed to limit the vibration of rotors through a bump. It is also found that gyroscopic effect causes problems in vibration isolation. Section 4 explores de-levitation
method and installation of gimbals as possible remedies to this problem. Finally, a
summary of simulation results from different input cases is made
Robustness and Control of a Magnetically Levitated Transportation System
Electromagnetic suspension of Magnetic Levitation Vehicles (Maglev) has been studied for many years as an alternative to wheel-on rail transportation systems. In this work, design and implementation of control systems for a Maglev laboratory experiment and a Maglev vehicle under development at Old Dominion University are described. Both plants are modeled and simulated with consideration of issues associated with system non-linearity, structural flexibility and electromagnetic force modeling. Discussion concerning different control strategies, namely centralized and decentralized approaches are compared and contrasted in this work. Different types of electromagnetic non-linearities are considered and described to establish a convenient method for modeling such a system. It is shown how a Finite Element structural model can be incorporated into the system to obtain transfer function notation. Influence of the dynamic interaction between the Maglev track and the Maglev vehicle is discussed and supported by both analytical results and theoretical examples. Finally, several control laws designed to obtain stable and robust levitation are explored in detail
Design of a wing section in ground effect: application to high speed ground transportation
This dissertation attempts to fully explain the aerodynamic ground effect phenomenon, which occurs when a wing flies over a nearby plane. The long-term motivation is to determine the feasibility of a train that achieves aerodynamic levitation above a flat guideway. Such a train would rely exclusively on lifting surfaces, rather than on steel wheels, lifting fans, or magnetic fields.;As a first step in the study of an aerodynamically suspended train, a wing section must be designed. This dissertation focuses on the preliminary design and the experimental investigation of a two-dimensional airfoil in ground effect. For application to high-speed ground transportation, the airfoil is assumed to fly at approximately six degrees incidence and a ground distance of ten percent of its chordlength. Both the theoretical analysis and the wind tunnel experiment utilize two airfoils that are mirror images of one another. The symmetry plane between the two airfoils models the presence of the ground. The theoretical preliminary design makes use of inviscid panel methods.;The work includes chapters on vehicles that use the aerodynamic ground effect, and on high-speed ground transportation systems. Possible directions for future research in the area of aerodynamically suspended trains are also suggested
Fourth International Symposium on Magnetic Suspension Technology
In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Fourth International Symposium on Magnetic Suspension Technology was held at The Nagaragawa Convention Center in Gifu, Japan, on October 30 - November 1, 1997. The symposium included 13 sessions in which a total of 35 papers were presented. The technical sessions covered the areas of maglev, controls, high critical temperature (T(sub c)) superconductivity, bearings, magnetic suspension and balance systems (MSBS), levitation, modeling, and applications. A list of attendees is included in the document
Advance control strategies for Maglev suspension systems
The Birmingham Maglev developed over fifteen years ago has successfully demonstrated
the inherent advantages of low speed maglev over comparable wheeled systems. It
remains the only commercially operational Maglev in the world today. To develop the
next generation of Maglev vehicles which will overcome some of the limitations of the
Birmingham system, such as chassis length and cost, the following issues are addressed
in this thesis.
1) The possibility of interaction between the chassis resonant frequencies and the
suspension control system causing poor ride quality and at worst instability, are
formally analysed. In the Birmingham vehicle a stiff chassis (fundamental bending
mode 40Hz) is used avoiding significant interaction with the suspension controller.
Using advanced control strategies the low frequency chassis resonances can be
controlled allowing a vehicle structure to be used with a fundamental bending
mode of about 12Hz.
2) A modem control strategy is developed which delivers an improved ride quality
compared with the present classical control system despite having to operate with
a 'soft' chassis. Kalman filters are digitally implemented and conclusions drawn
about their performance. The classical control strategy is also successfully
demonstrated on a 3 m long 'flexible beam' rig.
3) An associated Maglev suspension problem for the response to ramp inputs such
as the transition onto gradients which causes either a large steady state tracking
error or a worsening ride quality is addressed by modern control theory using
integral feedback techniques and classical theory using third order filters. These
controllers are globally optimised by a multi-objective parameter optimisation
system which formally considers the conflicts inherent in a suspension system
between response to stochastic inputs and deterministic inputs