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High-speed maglev system is a hot research topic nowadays in the field of high-speed ground transportation. Characteristics of the track irregularity of high-speed maglev system is quite different due to its contactless vehicle-rail relationship and segmented track compared with traditional railway. However, research on maglev track irregularity is still insufficient. This paper summarises, for the first time, the track inspection data collected on Shanghai Maglev Demonstration Line (Shanghai Line) since 2006, and describes the main filtering methods and parameters for acceleration and gap signals, taking into account the characteristics of maglev track. Track irregularity is then determined using the inertial measurement principle. The measured track spectrum on Shanghai Line calculated by the Welch method obeys a chi-square distribution with 2 degrees of freedom, indicating that different track qualities can be transformed by probability methods according to the research requirements. Based on the samples obtained over the past 15 years, and referring to the seven-parameter model of the railway system, a high-speed maglev track spectrum is obtained by the fitting method, parameters of which are obtained by applying the damped least squares method. Preliminary vehicle dynamic analysis is conducted utilising the inverted excitations derived from the measured spectrum of the Shanghai Line. [ABSTRACT FROM AUTHOR]

To reduce the vehicle-bridge coupled vibration of a new-type maglev vehicle with mid-mounted suspension (MVMS) on a curve and increase its curve-passing speed, the forced guidance device (FGD) for MVMS is designed and the effectiveness of the FGD is proved. Firstly, on the basis of the FGD for HSST (High Speed Surface Transport) maglev vehicle and the geometric relationship between the movable sliders and the cabin as MVMS passes through a curved track, the FGD scheme for MVMS was designed. Secondly, the dynamic models with 5-bogies MVMSs (with and without FGD), control system, 11 flexible bridges, and track irregularities were established. Finally, the vehicle-bridge coupled vibration response of MVMSs on the curved track was analysed. Results show that the accelerations of the bridges, levitation modules, and cabin can be reduced significantly by installing FGD, especially at higher speeds. Compared to the accelerations without FGD, the maximum lateral and vertical accelerations of each bridge midspan can be reduced respectively by 56% and 43% at the speed of 45 km/h, those of the levitation modules can be reduced by 48% and 90%, respectively, and those of the cabin can be reduced by 37% and 53%, respectively. [ABSTRACT FROM AUTHOR]

In order to find out the influence of suspension form on the medium and low-speed maglev system, first, the transfer functions of the heaving and pitching motions of the two kinds of levitation modules equipped with the two suspensions, respectively, were derived and compared. Second, the coupled-vibration equations of the levitation module, cabin and bridge were presented. At last, two kinds of dynamic models were built to analyse the dynamic performance of the two maglev vehicles. Results show that the effect of the suspension form on the levitation module response is significant, but that on the cabin and bridge is insignificant. The maximum air-gap fluctuation in MVES (maglev vehicle with end-mounted suspension) is about twice that in MVMS (maglev vehicle with mid-mounted suspension) at the speed of 160 km/h. Moreover, the maximum current in MVES is 7.4 A larger than that in MVMS, and the mean power consumption of the levitation system in MVES is 1.2 kW larger than that in MVMS. On the whole, according to the dynamic responses of the two maglev vehicles, the mid-mounted suspension is more conducive to reducing the air-gap fluctuation, current and power consumption of the levitation system. [ABSTRACT FROM AUTHOR]

A comparative study was conducted on Levitation Frame with Mid-set Air Spring (LFMAS) and Levitation Frame with End-set Air Spring (LFEAS). First of all, the work done by air spring force and by track excitation on two levitation frames were analysed, respectively, and the mechanism of the low dynamic interaction of LFMAS with guideway was explained theoretically; then, dynamics simulation and coupled vibration test on LFEAS and LFMAS were carried out using coupled vibration test bench of single levitation frame. Theoretical equations show that both the work done by the air spring forces and by track excitation on LFMAS are less than those on LFEAS under the same vibration condition, demonstrating that LFMAS has better levitation stability than LFEAS. Simulation and test results show that the fluctuation of levitation gap as well as the vibration acceleration of track beam platform, levitation frame and car-body of LFMAS are all smaller than those of LFEAS; with the increase of sine excitation frequency or vehicle speed, the superiority of LFMAS in dynamics performance is more obvious. [ABSTRACT FROM AUTHOR]

The violent coupled vibration between the electromagnetically levitated vehicles and the steel switch girder had happened in several engineering practices, especially under the very low speed conditions. In order to simulate accurately the abnormal vibration and explore its underlying causes, this paper develops a distributed co-simulation framework, including maglev vehicle dynamic modelling by SIMPACK software, switch dynamic modelling by ANSYS software and a co-simulation coupler developed by C++ language to implement co-simulation of maglev vehicles and switch girder system. Dynamic response of maglev vehicles and switch girder system under various conditions of running speed and structural damping ratio are simulated and compared to obtain the mechanism and characteristics of coupled vibration. These results agree well with dynamic phenomena happened in the engineering practices. Further analysis shows that the levitation modules are impacted in turn by the vertical misalignments and rotation angles at both ends of switch girder, so that vibration energy of the switch girder cannot be attenuated rapidly by its relatively small damping and dead weight. The severe coupled vibration can be suppressed effectively by adding the tuned mass dampers, but improving constraints of switch girder and optimizing levitation control parameters should be paid more attention in the future. [ABSTRACT FROM AUTHOR]

To evaluate the dynamics of the coupled medium–low-speed maglev train-turnout system, a rigid-flexible dynamics model of the coupled system was developed based on multi-body dynamics theory and finite element method. The modal and dynamic responses results obtained from the model calculations were compared with the field test results, and the dynamic interaction characteristics of the coupled system under different operating conditions were investigated using the validated simulation model. Research results show that both the increase in the support stiffness of the turnout and the rational choice of some key parameters of the coupled system will ensure the levitation stability of the train. Increasing the support stiffness of the turnout by means of adding a trolley to support in the middle of the long-span girder (LSG) facilitates the stable levitation of the train when standing still above the turnout and improves the dynamic performance of the coupled system. By optimising some key parameters, including limiting the flatness of the magnetic pole surface of the turnout track within 1.5 mm, and taking the vertical damping of the air springs for overloaded train within 9000∼11,000 N·s/m, significant improvements in the dynamic performance of the train and the turnout can also be achieved. [ABSTRACT FROM AUTHOR]

To investigate the dynamic effects of bolster-hanger length on the 600 km/h high-speed EMS maglev vehicles, a dynamic model of three-car trainset is established, considering the kinematic relation of the bolster-hanger mechanism and the active levitation/guidance control system. Model validation is carried out by comparing simulated results with test results of Shanghai high-speed maglev vehicles. Then, the proposed model is used to simulate the dynamic response of maglev vehicles with four different hanger lengths of 0.12, 0.18, 0.24, 0.36 m and passing through the straight track, the horizontal curve and the vertical curve. Simulated results indicate that because of the too short hanger maglev vehicles cannot pass through safely the sharp horizontal curve, and deteriorate the lateral dynamic performance of maglev vehicles on the straight track. The too long hanger may increase the lateral displacement of the carbody and lateral forces of rubber stops of maglev vehicles on the large-radius horizontal curve. The hanger length has little influence on the dynamic response of maglev vehicle on the vertical curve. In sum, the medium-long (0.24 m) hanger can provide a stronger curve negotiation capacity and better ride quality of high-speed maglev vehicles. [ABSTRACT FROM AUTHOR]

The superconducting electrodynamic suspension (EDS) train, which has reached a manned speed of 603 km/h in 2015, and is therefore regarded as one of the most attractive technologies for the higher speed train. In the superconducting EDS train, the discrete layout of ground null-flux coils causes the additional electromagnetic ripples towards the bogies, making the vibration control more essential to ensure the running performance. In this work, a fourteen-degree-of-freedom dynamics model of superconducting EDS train, was established to explore the effective strategy for vibration reduction. This model uses the time domain wave of track irregularity spectrum as the input of vehicle system. MATLAB/Simulink and "Zhai's method" are both adopted to solve the vehicle dynamic model and validate the model. Using these models, the effectiveness of the proportional force and maximum force for the primary suspension was examined. The results show that the maximum force strategy has advantage over the proportional force strategy in terms of energy consumption and vibration sensitiveness. However, the electromagnetic damping control can only suppress the vibration of bogie. To achieve an overall vibration control, the "ON-OFF" sky-hook damping was further introduced to the secondary suspension to suppress the vibration of car body. We find that, the control effect is preferable with the damping value being between 5 kN·s/m and 10 kN·s/m. Therefore, the cooperative control, considering both the primary and secondary suspensions, is necessary to meet the Urban Tracked Aircushion Vehicle Standard and provide theoretical supports for the suspension design of superconducting EDS train. [ABSTRACT FROM AUTHOR]

In recent years, low and medium speed maglev (LMSM) transportation system has been greatly promoted in China to meet different social demands. Accordingly, a LMSM train using levitation frames with mid-set air springs has been developed, and it is necessary to investigate the dynamic characteristics of its train-track-bridge coupled system. First, environmental vibration tests were conducted on the bridge to study its self-vibration characteristics. Then, field tests were carried out on this coupled system within the 60 km/h speed range. Subsequently, a three-dimensional rigid-flexible coupled dynamics model of the system was developed to evaluate its dynamic behavior at higher speeds. Results show that the first-order vertical and lateral bending frequencies of the bridge are 7.32 Hz and 6.00 Hz, respectively; train speed has little effect on the vertical dynamic displacement of the track-bridge system, yet has a significant impact on the acceleration responses of the coupled system; key dynamic indicators of the bridge meet the relevant requirements; the vertical ride quality of car body is not so good as that in the lateral direction, but on the whole the train has "Good" ride quality. These results can provide a useful reference for the optimal design of LMSM transportation systems. [ABSTRACT FROM AUTHOR]

The levitation bogie of the TR-series maglev vehicle is redesigned by adding an intermediate buffer layer between the levitationbogie and the levitation module to improve the curve negotiation capacity of the high-speed maglev vehicle and reduce the vertical coupleddynamic effect of the vehicle and the track beam. As the existing TR08 maglev vehicle dynamic model has been verified by experiments, anew type of dynamic model of maglev vehicle is constructed by transplanting the functional module of TR08 model. The vehicle-elastic trackbeam coupled dynamic model and the vehicle-curved track dynamic model are established. Simulation analyses of the dynamic response ofvehicles and track beams show that: the curve negotiation capacity of the new-type maglev vehicle is better than that of TR08 type maglevvehicle; the resonance effect does not occur between the vehicle and the track beam; the vertical dynamic displacement of the track beammid-span decreases by 23% compared with the TR08 type; the redesigned levitation bogie structure and the track beam have less dynamicinteraction, indicating that the working environment of the electromagnet in the new maglev vehicle has been improved, which can effectivelyreduce the burden of electrical decoupling of the control system. [ABSTRACT FROM AUTHOR]

The suspension system of maglev train has intrinsic nonlinear characteristics. The identification processing ability of nonlinear terms and the control accuracy of control algorithm have an important influence on the suspension stability of the train. Especially when the track stiffness is weak, it is easier to affect the suspension stability under the action of small deformation, resulting in the phenomenon of point dropping/rail smashing. Starting from the nonlinear dynamic modelling of maglev suspension system, this paper focuses on the system parameter identification of nonlinear terms and the design of nonlinear control algorithm. Based on Hopfield neural network, the error function and network identification scheme are constructed. In addition, in order to further improve the control accuracy and system robustness, radial basis function (RBF) network adaptive control is carried out based on the identified system model, and the control performance is improved by RBF network approximation principle. Through the numerical simulation analysis, it can be found that the identification effect is good. Moreover, the proposed control algorithm has an obvious effect on improving the control performance and system robustness, which verifies the reliability of the identification results and the control algorithm. [ABSTRACT FROM AUTHOR]

In order to reveal the abnormal vibration of a newly developed 200 km/h medium-speed maglev vehicle with mid-mounted permanent magnet linear synchronous motors at specific speeds, field vibration tests at different running speeds are carried out and analysed in this paper. The accelerations of the linear motor and levitation module were measured during powered running as well as idle running. Data analysis indicates that the vertical and longitudinal forced resonance of the PMLSMs result in the abnormal vibrations. The idle running tests imply that the excitation force comes from the vertical attraction force between the permanent magnets of the motor and steel sleepers. These results point out the direction of dynamic optimisation of the bogie. [ABSTRACT FROM AUTHOR]

This study presents a more realistic modelling of the maglev-based high-speed railway line in Shanghai, China. Focus is placed on an accurate simulation of the two subsystems: the train subsystem including the magnets and the viaduct subsystem including the modular function units of the rails. The electromagnet force-air gap model with a proportional-derivative (PD) controller is adopted to simulate the interaction between the maglev train via its electromagnets and the viaduct via its modular function units. The flexibilities of the rails, girders, piers and associated elastic bearings are all considered in the modelling of the viaduct subsystem to investigate their effects on an interaction between the two subsystems. By applying the proposed model to the Shanghai maglev line, the essential characteristics of the coupled system can be duly captured. The accuracy and effectiveness of the proposed approach are then validated by comparing the computed dynamic responses and frequencies with the measurement results. It is confirmed that the proposed modelling with a detailed simulation of the magnets and modular function units can duly account for the dynamic interaction between the train and viaduct systems. Moreover, the effects of the inclusion of the flexibilities of the rails, girders and elastic supports to the response of the coupled system are respectively investigated, the results of which prove that their involvements are essential to the accurate prediction of the response of the coupled maglev train-viaduct system. [ABSTRACT FROM AUTHOR]

To reduce the vehicle/guideway-coupled vibration and improve the levitation stability of medium-low-speed maglev vehicle, a new type of levitation frame with air springs installed in the middle of the longitudinal beams is developed. This levitation frame with mid-set air spring (LFMAS) is studied comparatively with the levitation frame with end-set air spring (LFEAS) in electromagnetic levitation mode. The coupling degrees of the two kinds of frames are analysed by vertical motion equations; the energy consumptions for levitation control system to overcome the spring resistance in the whole adjustment process are calculated by the energy method; and the vibration accelerations are compared by dynamics analysis and bench test. The equations indicate that the LFMAS has a better decoupling effect and lower energy consumption than that of the LFEAS in any adjustment process. Simulation and test results show that the LFMAS can effectively reduce the vibration acceleration at a low-speed and achieve a better levitation stability in working conditions, validating that the LFMAS has a better levitation performance and adaptability to the guideway, which is attributed to the mechanical decoupling of the levitation module. It is expected that this new levitation frame will be very helpful in enhancing levitation stability and the ride index of medium-low-speed maglev vehicle. [ABSTRACT FROM AUTHOR]

Normally, Maglev (magnetic levitation) vehicles run on elevated guideways. The elevated guideway must satisfy various load conditions of the vehicle, and has to be designed to ensure ride quality, while ensuring that the levitation stability of the vehicle is not affected by the deflection of the guideway. However, because the elevated guideways of Maglev vehicles in South Korea and other countries fabricated so far have been based on over-conservative design criteria, the size of the structures has increased. Further, from the cost perspective, they are unfavourable when compared with other light rail transits such as monorail, rubber wheel, and steel wheel automatic guided transit. Therefore, a slender guideway that does have an adverse effect on the levitation stability of the vehicle is required through optimisation of design criteria. In this study, to predict the effect of various design parameters of the guideway on the dynamic behaviour of the vehicle, simulations were carried out using a dynamics model similar to the actual vehicle and guideway, and a limiting value of deflection ratio of the slender guideway to ensure levitation control is proposed. A guideway that meets the requirement as per the proposed limit for deflection ratio was designed and fabricated, and through a driving test of the vehicle, the validity of the slender guideway was verified. From the results, it was confirmed that although some increase in airgap and cabin acceleration was observed with the proposed slender guideway when compared with the conventional guideway, there was no notable adverse effect on the levitation stability and ride quality of the vehicle. Therefore, it can be inferred that the results of this study will become the basis for establishing design criteria for slender guideways of Maglev vehicles in future. [ABSTRACT FROM AUTHOR]

Dynamic instability, that is, resonance, may occur on an electromagnetic suspension-type Maglev that runs over the elevated guideway, particularly at very low speeds, due to the flexibility of the guideway. An analysis of the dynamic interaction between the vehicle and guideway is required at the design stage to investigate such instability, setting slender guideway in design direction for reducing construction costs. In addition, it is essential to design an effective control algorithm to solve the problem of instability. In this article, a more detailed model for the dynamic interaction of vehicle/guideway is proposed. The proposed model incorporates a 3D full vehicle model based on virtual prototyping, flexible guideway by a modal superposition method and levitation electromagnets including feedback controller into an integrated model. By applying the proposed model to an urban Maglev vehicle newly developed for commercial application, an analysis of the instability phenomenon and an investigation of air gap control performance are carried out through a simulation. [ABSTRACT FROM PUBLISHER]

For electromagnetic suspension (EMS) type urban Maglev vehicles using a U-shaped electromagnet, the levitation and guidance forces are generated by only one electromagnet. Although the levitation force is actively controlled by changing the voltage of the electromagnet, the guidance force is passively determined by the levitation force. In addition, the curve negotiation performance of EMS-type urban Maglev vehicles using a U-shaped electromagnet must be considered, because an urban guideway may have some curves with shorter radii. It is, therefore, necessary to predict the curving performance with the greatest accuracy possible, in order to improve electromagnetic suspension and establish guideway design specifications. The objective is to establish a new dynamic modelling technique, so as to achieve more realistic curving simulation and thus to more accurately evaluate the curving performance of an EMS-type Maglev vehicle. The use of a full vehicle multibody dynamic model is proposed, and is applied to the evaluation of curving performance. Design changes are also investigated to obtain the bogie design directions for minimising variation in the lateral air gap, which is a criterion for curving performance. [ABSTRACT FROM AUTHOR]

In magnetically levitated (Maglev) transportation systems, especially in electromagnetic suspension system (EMS) type Maglev systems, highly accurate prediction of ride quality is very important in order to reasonably relax guideway construction tolerances or constraints and stiffness while meeting the specification for ride comfort, thereby reducing guideway construction and maintenance costs. A full vehicle multi-body dynamic model is proposed, to facilitate a rigorous ride quality prediction of an EMS-type Maglev vehicle. Using the more realistic dynamic model proposed in this paper, the effects of guideway deflection limits, surface roughness, and levitation control system parameters on ride quality are studied numerically. The results obtained from the simulation studies are then used to facilitate a discussion of the trade-off between guideway smoothness and vehicle suspension. It can be expected that these studies could suggest cost-effective specifications for guideway construction tolerances and stiffness and EMS. [ABSTRACT FROM AUTHOR]

The levitation control system in an electromagnetically levitated vehicle controls the voltage in its winding to maintain the air gap, which is the clearance between the electromagnet and the guideway, within an allowable range of variation, while strongly interacting with the flexible guideway. Thus, the vibrational characteristics of the guideway play an important role in the dynamics of Maglev (magnetically levitated) vehicles that utilise an active electromagnetic suspension system. In this study, the effects of the guideway's vibrational characteristics, such as natural frequency and damping, on the dynamics of the Maglev vehicle UTM-02 are numerically and experimentally analysed. From these analyses, the coupled equations of motion of the simplified vehicle-guideway model with three degrees of freedom are derived. Eigenvalues are calculated and frequency response analysis is also performed, in order to obtain a clear understanding of the dynamic characteristics resulting from the guideway's vibrational characteristics. To verify the numerical results, air gap tests of the urban Maglev vehicle UTM-02 are also carried out. These results lead us to recommend that the natural frequency of the guideway be decreased by increasing mass density rather than by decreasing rigidity, and that its damping ratio be increased in the Maglev vehicle UTM-02 employing a five-state feedback control law as a levitation control law. [ABSTRACT FROM AUTHOR]

Modelling of a high-speed MAGLEV train including the whole mechanical system of one vehicle with optimised suspension parameters and all controlled electro magnet pairs in vertical and lateral directions is discussed and simulation code is generated based on SIMULINK/MATLAB. For the control system design, linear quadratic control for minimum control energy is used for each single mass magnet. Simulation results are presented with vertical and lateral random guide way irregularities with comparison of individual and modal control for vertical levitation magnets. [ABSTRACT FROM AUTHOR]

A new dynamic model of a high-speed EMS maglev vehicle/guideway interaction is presented. The model considers the vehicle and the guideway as an integral system and couples vertical interaction with lateral interaction. The vehicle subsystem is modeled as a multi-body system, which runs on the guideway with a constant velocity. The guideway substructure is modeled as an elastic beam. The attractive magnetic forces between vehicle and guideway are decided by controller, observer, and filter. A special simulation program is developed. Numerical results of the program are compared with test results. The results show that the coupling model is appropriate and the simulation program is credible primarily. Applications of coupling model to the investigation of the effect of irregularities on maglev system are reported at the end of the paper. The studies in this paper can be used to evaluate and optimize dynamic performances of the high-speed EMS maglev system. [ABSTRACT FROM AUTHOR]

The research and development (R & D) of maglev technology had made a great progress in China since the early 1980s. Especially, a 35 km-long Shanghai high-speed maglev railway employing the German Transrapid system began to be constructed on March 1, 2001. Based on the Transrapid system, the paper develops a 10-degree-of-freedom model of maglev vehicle running over three types of guideways with constant speed. Random guideway irregularities are discussed and taken into account for simulation of the vehicle response and for evaluation of the ride comfort. Using the direct time integration method and the discrete fast Fourier transform (DFFT), random responses of the maglev vehicle-guideway systems are obtained and analyzed. Numerical results show that the resonant frequency of car body acceleration response is 0.5-1 Hz, and there is a 2.2 Hz periodic vibration due to the periodic configuration of rigid piers when the maglev vehicle travels over the elevated-beam guideway. The car body acceleration power spectral density (PSD) curves meet well the ride quality criterion of the urban tracked aircushion vehicle (UTACV) and the maximum acceleration of car body is less than 0.05 g. Moreover, the Sperling ride index values are less than 2.5 as long as the operational speed is less than 450 km/h. It is concluded that the maglev vehicle ride quality is quite well. [ABSTRACT FROM AUTHOR]

A simple demonstrator for a magnetic levitation vehicle (MagLev) based on repulsive suspension forces generated by permanent magnets is presented. The lateral and yaw motions are stabilized using controlled electromagnets. A mathematical model, aimed mainly at defining the control strategy, has been developed and then experimentally validated using the demonstrator. Two different control strategies have been tested, namely a zero position error and a zero average current control strategy. Both proved to grant a stable behaviour and to effectively counteract external force disturbances. This demonstrator will be used in future research on MagLev vehicles but also on magnetic suspensions in general. [ABSTRACT FROM AUTHOR]

Highlights the Third International Symposium on Speed-Up and Service Technology for Railway and MAGLEV Systems to be held on August 19-22, 2003 at the Tokyo University of Agriculture and Technology in Japan. Organizer and sponsor of the symposium; Topics to be discussed; Contact information.