Dynamic Modeling of the Three-Dimensional Seated Human Body for High-Speed Train Ride Comfort Analysis

Achieving higher operation speeds safely and comfortably is yet a significant challenge in the railway industry. The rail irregularities and wheel-rail interactions in a train running at high speeds may result in large-amplitude vibration in the train’s car body and affect passengers by reducing ride comfort. The train suspension systems have a crucial role in reducing the vibration and improving ride comfort to an acceptable level. In this context, an exclusive semi-active magneto-rheological (MR) damper with a favorable dynamic range was designed and fabricated. The MR dampers were installed in a high-speed train’s secondary lateral suspension system in replacement of original passive hydraulic dampers, with intent to mitigate vibration of the car body and keep the ride comfort in a proper level at low and high running speeds. A unique full-scale experimental investigation on the high-speed train equipped with MR dampers was carried out to evaluate the MR damper functionality in a real operating situation. The full-scale roller experiments were conducted in a vast range of speeds from 80 to 350 km/hr. At each speed, different currents were applied to the MR dampers. The car body dynamic responses were collected to evaluate the ride quality of the train. Ride comfort indices under various train operating conditions are calculated through Sperling and UIC513 rules. This study reveals that the designed MR dampers effectively reduce the car body’s rolling motion. According to Sperling ride comfort index, the car body vibration was “clearly noticeable” at some running speeds when adopting the MR dampers, but it was not unpleasant. Besides, a “very good comfort” was achieved according to the UIC513 criterion. Also, no train instability was whatsoever observed at high speeds. This experimental investigation bears out the capability of the devised MR damper to achieve desirable ride comfort under high running speeds.

Analytical results indicate that there is a wide variation in roll and lateral behavior on curves at unbalance speeds, for passenger car suspensions in use today. This paper categorizes passenger car types and analyzes behavior under the action of quasi-static lateral forces such as can occur on curves. Understanding this behavior can be important in providing guidelines for developing new designs that operate at relatively high unbalance speeds while still retaining safe operation, good ride quality and other performance related to suspension system design. The approach taken is to develop equations of motion in terms of the physical parameters that must be known in order to determine carbody roll and lateral motions due to lateral loads and laterally offset component weights. These equations are then rearranged in terms of parameters that characterize quasistatic and dynamic performance in a form that facilitates making general statements about the comparative influence of categories of cars on carbody roll and lateral motions, and the resultant increase in wheel unloading, as functions of lateral load. Results are presented for ranges of cars in each category. Roll and lateral motions of existing designs can be estimated by using the physical parameters of the existing design to calculate the parameters used in the equations presented in the paper and then using those equations to calculate estimates of the roll and lateral motions. For contemplated new designs either physical parameters can be selected and motions calculated, or values of the parameters used in the equations presented in the paper that result in desirable levels of roll and lateral motions can be used as trial values for initial and later iterations of the design. The analytical approach has been subjected to limited correlation with static lean test results with good agreement found.

To study the ride comfort of high-speed train passengers, a detailed human body–seat–vehicle–track coupled model is developed. This model adopts a dual-axis human-body dynamic model and considers the nonlinearity of the primary and secondary suspensions and the wheel–rail contact condition. Additionally, the input wheel/rail irregularity excitation data are measured for a high-speed railway line in China. According to the model, the root-mean-square (RMS) values of the acceleration for the passenger head at different positions of the car body are determined, and the effects of the car-body loading conditions, speed, and seat support parameters on the head vibration characteristics are studied. The results indicate that the RMS value is the highest for the passengers sitting in the front row near the window seat, followed by those sitting in the middle row of the car body. There are small differences in the RMS value between the passengers sitting on the left and right sides of the same row in the car body. At a certain speed, the track irregularity stimulates the rolling and pitching motions of the train. Therefore, effective methods should be implemented to avoid the inherent characteristics of the car body. Although an increase in the seat support stiffness intensifies the high-frequency vibration, it reduces the low-frequency vibration in the range of 0–15 Hz, reducing the RMS value of the head acceleration. When the train is loaded, the effect of passengers on the car body is similar to that of a damper or mass element, which can reduce the car-body vibration and enhance the ride comfort.

A 3D rigid-flexible human-seat-vehicle-track coupling model is proposed to analyze high-speed train ride comfort. The seated human model is built based on the multi-body dynamic method. The human multi-axis excitation measurement data determines the model parameters. The detailed FE (finite element) car body model is built, and the model is calibrated by laboratory modal tests. The dynamic behavior of the high-speed train, running on both straight and curved tracks, is analyzed by using the rigid-flexible human-seat-vehicle-track coupling model. Then, the effect of the seat support parameters on the ride comfort of the high-speed train is analyzed, when the train travels on curved tracks. The results show that using the rigid car body model can overestimate the ride comfort of the high-speed train. The lateral and rolling motion of the car body, induced by curves can worsen the lateral dynamic performance of the passenger seats. At the different seat positions and for the different configurations of seats (three-abreast and two-abreast), selecting proper stiffness of the seat-floor and seat-sidewall supports can achieve comfort for the passengers.

Classical suspension (oil damper mounted in parallel with compression helical spring) is replaced by a colloidal suspension, in which case the spring can be omitted. Hence, structural simplification, accompanied by a compact and lighter design can be achieved. Oil is replaced by an ecological mixture of water and water-repellent nanoporous particles of silica (artificial sand). Travel tests using a V8 4.3L auto vehicle equipped with classical and colloidal suspensions were performed. Ride comfort (ISO 2631 method) was evaluated during travel (speed: 5–40 km/h) on a normal road with an asphalt step (height: 37 mm; width: 405 mm), for various values of the tire inflation pressure (150–250 kPa). On normal road without step the travel speed was increased up to 80 km/h. Acceleration at seat, seat-back, and feet surfaces was processed using the commercially available DEICY system for ride comfort evaluation. Spring omission, accompanied by 60 % reduction of the outer diameter, and 30 % reduction of the mass was achieved both for the frontal and rear colloidal suspensions. Results concerning the ride comfort were validated in the case of classical suspensions. Relationship between the travel speed of the vehicle and level of vibration perception was obtained for various values of the tire inflation pressure. Ride comfort decreased at augmentation of the travel speed and the tire inflation pressure. Since the colloidal spring constant was 6 times larger than the constant of the compression helical spring, colloidal suspension provided 1 rank lower ride comfort than the classical suspension. Pitching and rolling movements were not considered during the estimation of the ride comfort. Relation between the lateral acceleration and the rolling attitude angle was experimentally determined. Ride comfort results were explained by taking into account the vehicle behaviour during frontal, rear and superimposed impact excitations, in correlation with the variation against travel speed of the frequency weighting proposed by the ISO 2631. Although the colloidal suspension was found to provide inferior ride comfort than the classical suspension, results obtained so far are encouraging since better performances are to be expected by softening the colloidal spring, and by redesigning the suspension including the stabilizers.

The influence of the rolling motion and the lateral motion caused by the rolling motion on electromagnetic performance of combined levitation and guidance EDS maglev train is calculated and analyzed. First, the coupling mechanism between the rolling motion and the lateral motion caused by the rolling motion is discussed in detail. Then, the mathematical model and analytic method are presented, and the formulas of levitation force, guidance force, and rolling torque are derived. By decoupling the lateral motion and the rolling motion, the coupling stiffness and equivalent rolling stiffness are obtained. Third, the variation trends of levitation force, guidance force, and rolling torque with lateral offset after rolling motion occurs are discussed, the redistributions of guidance force and rolling torque with levitation height are predicted, and the coupling stiffness and equivalent rolling stiffness at different speeds are compared. Meanwhile, the three-dimensional finite-element model is established to verify the correctness of the analytical model. Finally, the analytical results are experimentally verified.

Conducting the study on the comfort of high-speed train drivers in a windy environment, this paper based on the logical sequence of “train aerodynamic characteristics - vehicle dynamic response - human biomechanical properties - human body comfort evaluation”. Taking the domestic CRH3 high-speed train as the research object. Firstly, the aerodynamic loads acting on the car bodies of the train under different wind speeds and different vehicle speeds were calculated. Then considering the effect of the wheel-rail adhesion and the irregularity of the track line, establish a vibration transfer model of ‘rail - wheelset - bogie - carriage - seat’, the aerodynamic loads are loaded onto the train to calculate vehicle dynamics and train vibration response under different operating conditions, the vibration characteristics of carriages and seats are obtained. Subsequently, the seat-human vibration transfer model were established and the seat vibration response was introduced into the human dynamics model to calculate the vibration response of different body parts of the driver under different operating conditions. And on the basis which are mentioned above, we summarized the influence rule of wind speed and train speed on human vibration response, From the human body's own point of view, the main factors affecting comfort and the mechanism of action were analyzed. Finally, the comfort standard was integrated to evaluate the comfort of the driver.

Vehicle automation is among the best possible solutions for traffic issues, including traffic accidents, traffic jams, and energy consumption. However, the user acceptance of automated vehicles is critical and is affected by riding comfort. In addition, human factors in automated vehicle control should be clear. This study evaluates the effect of different courses on driving comfort in automated vehicles using field experiments with 25 subjects. This study focused on lateral motion, but speed control was not targeted. Further, generating a path for obstacle avoidance and lane keeping, which have several constraining conditions, was also not targeted. Rendering a comfortable path is beneficial for developing an acceptable system as a car developer and for building new curves for automated or driving assistance systems from the perspective of construction. The automated vehicle drove at a speed of 30 km/h on four courses, namely, clothoid, two types of spline curves, and arc, based on the real intersection. Each participant sat on both the driver and passenger seat and answered a questionnaire. The experimental data indicated the clothoid course to be the most comfortable, while the arc was most uncomfortable for a significance level of 1%. These tendencies are applicable to driver and passenger seats, all genders, and experiences and will be beneficial for human factor research in automated vehicle control.

A train seat–human body coupled dynamics model was established to predict the ride comfort of high-speed trains. The train and track and the seat and human body were both coupled in the model. An on-site vibration experiment in a high-speed train was carried out to calibrate each part of the train seat–human body coupled dynamics model. Based on the evaluation method proposed by BS EN 12299:2009, the distribution of ride comfort in the carriage and the effect of seat cushion stiffness and damping on ride comfort were analyzed systematically. The results showed that the seats in the middle of the carriage had the best comfort performance, while those near the side wall and close to the position where the suspension force of the second series was acting were less comfortable. The seat cushion stiffness and damping had great effect on ride comfort.

The rail vehicle industry wants to produce vehicles with higher speeds, to maintain and increase its market share. However, when the speed of the vehicle increases, it may have an undesirable effect on ride comfort, in terms of ride dynamics. Recent developments towards lighter and faster vehicles make the problem of ride comfort at higher speeds increasingly important. Focusing on the behavior of flexible rather than rigid body behavior should not be neglected when designing long and light car bodies. There are several approaches to incorporate body flexibility in multibody simulations and they have some superiorities and weaknesses. In this study, an efficient and accurate vertical dynamic model for the ride comfort analysis is developed and implemented in a commercial object-oriented modeling (OOM) software Dymola (2015 FD01) which uses the open-source code Modelica. This model includes car body flexibility with the assembling of a rigid body approach. The developed model is compared to a three-dimensional vehicle model in the commercial Vampire software (Pro V5.50) at different velocities. For the vertical ride comfort analysis, the ISO 2631-1 standard was used for both the developed model and the three-dimensional model. The results are presented as acceleration history and awrms—weighted r.m.s (root mean square) of accelerations—as required by the standard. The developed model has shown its feasibility in terms of its efficiency and accuracy for the vertical ride comfort analysis. The accuracy of the model is evidenced by the fact that the car body vibration level at high speeds shows minor differences compared to the results of the Vampire, which is a validated commercial software in the area of rail vehicle dynamics. The approach involving the assembly of rigid bodies is applied for the first time for high-speed trains in dynamical modelling, with flexible car bodies for ride comfort analysis. Furthermore, it can be used for parametrical studies focusing on ride comfort, thereby offering a quite beneficial framework for addressing the challenges of ride comfort analysis in high-speed rail vehicles. Improvements for and analyses of other aspects are also possible, since the optimization and other useful libraries are readily available in Dymola/Modelica.

Unmanned Aerial Vehicle (UAV), especially fixed wing, are widely used to carry out various missions, namely civil and military missions. To support the implementation of this mission, it is necessary to develop an intelligent automatic control system (autopilot). In this paper, an autopilot system with adaptive neuro fuzzy PID control is developed to control lateral (pitch) and longitudinal (roll) motion, by taking advantage of PID, fuzzy, and neural network control. Therefore, robust controls which can handle non-linear conditions can be formed. This paper aims to determine the performance of adaptive control of neuro fuzzy PID controllers for longitudinal and lateral motion on UAV. The result shows that adaptive control of neuro fuzzy PID are able to control the lateral and longitudinal motion of the aircraft and able to compensate for interferences from environmental disturbances in flying condition, such as changes in direction and wind speed that causes changes in aircraft attitude. The control characteristics of neuro fuzzy PID adaptive control in lateral and longitudinal motion are relatively similar. Adaptive control of neuro fuzzy PID has better performance than fuzzy PID control, i.e., faster settling time and lower percentage of maximum overshoot.

This study is focused on the effects of bending and torsional flexural modes of the car body on the ride quality index of a high-speed train vehicle. The Euler–Bernoulli beam model is used to extract an analytical model for a high-speed train vehicle car body in order to investigate its bending and torsional flexural vibrations. The rigid model includes a car body, two bogie frames, and four wheelsets such that, each mass has three degrees of freedom including vertical displacement, pitch motion, and roll motion. The results obtained with the proposed analytical model are compared with experimental measurements of the car body response of a Shinkansen high-speed train. Moreover, it is determined that the bending and torsional flexural modes have significant effects on the vertical acceleration of the car body, particularly in the 9–15 Hz frequency range. Furthermore, the ride quality index is calculated according to the EN 12299 standard and it is shown that the faster the train the more affected is the ride quality by the flexural modes. In addition, the effect of coherence between two rail irregularities (the right and the left rails) on the results of the simulation is investigated. The results conclude that if the irregularities are completely correlated the torsional flexural mode of the car body does not appear in the response. Also, the first bending flexural mode in such cases is more excited compared with the partially correlated or uncorrelated rail irregularities. Therefore, the ride quality index in completely correlated cases is higher than other cases.

Unrestrained lateral and roll motion can result in a risk in the operational safety of high-speed trains (HSTs) system. This paper explores the backstepping control technique to curb these motions. The HST is a higher order multiple-input-multiple-output (MIMO) system consists of nonlinear coupled dynamics. The general uncertainties along with nonlinearities presented in the dynamics of the system are approximated with radial basis function neural network (RBFNN). Stability analysis of the proposed method is carried out using Lyapunov theory. Trajectory tracking simulations of HST system are carried out to validate the efficacy and usefulness of the proposed method which ensures that the tracking errors asymptotically converge to zero.

The aim of this paper is to investigate the derailment of a tilting railway vehicle on curved tracks that are experiencing the twin effects of rail irregularities and an earthquake. The nonlinear governing differential equations of motion for a tilting railway vehicle are derived using a heuristic nonlinear creep model and Kalker’s linear theory. The tilting vehicle is modeled as a 24-degree-of-freedom system, with the lateral, roll and yaw motions of each wheelset, as well as the lateral, vertical, roll and yaw motions of the bogie frames and the car body all taken into account. The derailment quotients and offload factors of a tilting railway vehicle experiencing the twin effects of an earthquake on its wheelsets, bogie frames and car body in the lateral direction, and rail irregularities acting on its wheelsets in the lateral direction are investigated at various tilt angles. The obtained results show that, in general, a derailment quotient and an offload factor evaluated with an earthquake taken into consideration are larger than those obtained without consideration of the earthquake. Moreover, the derailment quotient and offload factor of a wheelset increase with an increase in the tilt angle of the railway vehicle experiencing excitations from an earthquake and also rail irregularities. Finally, the effects of suspension parameters on the derailment quotient and offload factor of a wheelset are investigated. Taken together, it is clear that the influences of rail irregularities and an earthquake on the derailment of a tilting railway vehicle cannot be disregarded.

This paper presents the results of ride comfort analysis performed on the Morgantown People Mover system and a comparison of results of measurements for other modern transit vehicles. All ride comfort measurements were performed, employing the new Ride Comfort Meter Type II developed and built by Delft University of Technology in Holland. Principals of several ride comfort criteria in use are presented and compared. The proposed criterion of exposure duration for givem vibration levels by the International Organization for Standardization (ISO) were selected for ride comfort measurements. The portable Ride Comfort Meter provides single value measurements which correspond to ISO weighted RMS values of effective accelerations. Each measurement takes 15 seconds and is called the Ride Index (RI). Statistical methods were used to analyze the ride comfort data obtained. Resultant statistical means for vertical and lateral Ride Indices versus vehicle speeds in guideway curves and on straight sections are shown. Linear regression using all data points yielded Ride Index equations for describing the relation of vertical and lateral Ride Index to vehicle speed. Results of ride comfort are shown as the percentage of trip time which the vertical and lateral Ride Indices were exceeded. The ISO reduced comfort boundary is used as a basis to assess the comfort levels encountered at the Morgantown People Mover system. To provide a basis for comparison between the Morgantown system and other transit systems, additional ride comfort measurements were made at three other automated guideway systems and five conventional transit systems.