Solid-axle Wheelset Research Articles

Modeling of a two-axle rail vehicle for state estimation

A two-axle rail vehicle having solid axle wheel-sets is developed by using Kalman filter state estimator. Approximately 18 states (from all the 8 inertial measurements) are observed by developing a Kalman filter. A total of five gyroscopes and three accelerometers calibrate the lateral acceleration, yaw velocity of the vehicle and two wheel-sets roll velocity. All the vehicle states are observed by formulating the Kalman filter, moreover, the Kalman filter is also used to calculate the different parameters like cant angle and radius of the curvature of the track. The design of the rail vehicle is validated by comparing the actual results with the same from computer simulations. The simulation also helps to develop an optimal and novel controller to assess the performance of the design of an active steering system.

Improving Wheelset Stability of Railway Vehicles by Using an H∞/LPV Active Wheelset System

The complexity of railway vehicle structures has been part of an evolutionary process for almost two hundred years. Challenges such as increased weight, increased maintenance, higher costs and energy consumption have become common. The vision for future railway vehicles is to reduce complexity, hence enable simpler structures and reduce maintenance and cost, and of course various research challenges arise from this. In fact, a number of papers in the railway engineering literature have presented practical ways to control steering of railway vehicles to improve performance. The model of the railway wheelset is highly nonlinear, mainly due to the nature of the wheelset structure and the related wheel-rail contact forces involved during operation. In this paper, the simplest design in terms of retrofitting, the actuated solid-axle wheelset is considered, we investigate actively controlled wheelsets from a Linear Parameter Varying (LPV) control aspect. We use the grid-based LPV approach to synthesize the H∞ / LPV controller, which is self-scheduled by the forward velocity, as well as the longitudinal and lateral creep coefficients. The aim of the controller is to reduce the lateral displacement and yaw angle of the wheelset. Simulation results show that the proposed controller ensures the achievement of the above targets in the considered frequency domain up to 100 rad/s.

Benefits of mechatronically guided vehicles on railway track switches

Conventional rail vehicles struggle to optimally satisfy the different suspension requirements for various track profiles, such as on a straight track with stochastic irregularities, curved track or switches and crossings, whereas mechatronically guided railway vehicles promise a large advantage over conventional vehicles in terms of reduced wheel–rail wear, improved guidance and opening new possibilities in vehicle architecture. Previous research in this area has looked into guidance and steering using multi-body simulation models of mechatronic rail vehicles of three different mechanical configurations – secondary yaw control, actuated solid-axle wheelset and driven independently rotating wheelsets (DIRW). The DIRW vehicle showed the best performance in terms of reduced wear and minimal flange contact and is therefore chosen in this paper for studying the behaviour of mechatronically guided rail vehicles on conventional switches and crossings. In the work presented here, a mechatronic vehicle with the DIRW configuration is run on moderate and high-speed track switches. The longer term motivation is to perform the switching function from on-board the vehicle as opposed to from the track as is done conventionally. As a first step towards this, the mechatronic vehicle model is compared against a conventional rail vehicle model on two track scenarios – a moderate speed C type switch and a high-speed H switch. A multi-body simulation software is used to produce a high fidelity model of an active rail vehicle with independently rotating wheelsets where each wheel has an integrated ‘wheelmotor’. This work demonstrates the theory that mechatronic rail vehicles could be used on conventional switches and crossings. The results show that the mechatronic vehicle gives a significant reduction in wear, reduced flange contact and improved ride quality on the through routes of both moderate and high-speed switches. On the diverging routes, the controller can be tuned to achieve minimal flange contact and improved ride quality at the expense of higher creep forces and wear.

Robust control and actuator dynamics compensation for railway vehicles

ABSTRACTA robust controller is designed for active steering of a high speed train bogie with solid axle wheel sets to reduce track irregularity effects on the vehicle’s dynamics and improve stability and curving performance. A half-car railway vehicle model with seven degrees of freedom equipped with practical accelerometers and angular velocity sensors is considered for the H∞ control design. The controller is robust against the wheel/rail contact parameter variations. Field measurement data are used as the track irregularities in simulations. The control force is applied to the vehicle model via ball-screw electromechanical actuators. To compensate the actuator dynamics, the time delay is identified online and is used in a second-order polynomial extrapolation carried out to predict and modify the control command to the actuator. The performance of the proposed controller and actuator dynamics compensation technique are examined on a one-car railway vehicle model with realistic structural parameters and nonlinear wheel and rail profiles. The results showed that for the case of nonlinear wheel and rail profiles significant improvements in the active control performance can be achieved using the proposed compensation technique.

Modeling and Simulation of Predictive Maintenance Scheme for High Speed Railway Vehicles

This paper presents a signal based predictive maintenance strategy for high speed railway vehicle having solid axle wheelsets. Several railway operators still rely on manual inspection of rolling stock, which is costly and inaccurate. In this research work an accurate and cost effective method is proposed to monitor the condition of the wheelset of in service vehicles. In proposed method inertial sensors are used to measure the lateral and yaw dynamics of the wheelset. The condition of the wheelset is then predicted indirectly by exploiting the measured dynamic response. To show the effectiveness of the proposed method a simulation model of the proposed scheme is developed in Matlab/Simulink. The simulation results affirm the proposed idea.Keywords: Predictive Maintenance, Railway Vehicle, Wheelset

Electronic differential for tramcar bogies: system development and performance evaluation by means of numerical simulation

The dynamic behaviour of railway vehicles depends on the wheelset configuration, i.e. solid axle wheelset or independently rotating wheels (IRWs). The self-centring behaviour, peculiar of the solid axle wheelset, makes this kind of wheelset very suitable for tangent track running at low speed: the absence of the self-centring mechanism in the IRWs may lead to anomalous wheel/rail wear, reduced vehicle safety and passengers’ discomfort. On the contrary, during negotiation of the sharp curves typical of urban tramways, solid axle wheelsets produce lateral contact forces higher than those of IRWs. This paper illustrates an electronic differential system to be applied to tramcar bogies equipped with wheel-hub motors which allows switching from solid axle in tangent track to IRWs in sharp curve (and vice versa). An electro-mechanical vehicle model is adopted for the design of the control system and for the evaluation of the vehicle dynamic performances.

Self-tuning control for active steering of a railway vehicle with solid-axle wheelsets

The instability caused by the conical (or profiled) shape of a solid-axle railway wheelset can be overcome by proper design of the vehicle's primary suspension system but is generally difficult as some of the wheelset parameters, namely the conicity and creep coefficients, are time-varying. To maintain the wheelset stability at high speeds and satisfactory curving performance simultaneously over the whole range of the parameters' variations, the self-tuning linear-quadratic regulator (S-T LQR) for the primary suspension system of a high-speed two-axle railway vehicle has been developed. The objective of the controller was to minimize the lateral displacement of the wheelset relative to track centerline and its yaw angle, on straight and curved tracks. The Continuous-time Least-Absolute Error with Variable Forgetting Factor (C-T LAE+VFF) estimation algorithm has been used to estimate the wheelset parameters before being used in the calculation of the linear quadratic feedback control gain matrix. The simulation results show that the S-T LQR performed better than the fixed-gain LQR for both the conical and profiled wheelset, suggesting that the ability to estimate the time-varying wheelset parameters and use them in the feedback controller design is necessary to produce better primary suspension control performance.

Re-evaluation of the limitations of the railway wheelset: passive and active

The fundamental conflict between stability and steering of railway vehicles using the conventional wheelset with a solid axle and coned or profiled wheels may be resolved using various passive suspension arrangements or forms of active control. Various configurations are considered on a strictly comparative basis on the basis of their dynamic response and the corresponding energy dissipation in the wheel–rail contact patch as a basic indication of wear. Though the optimum performance of the wheelset may be achieved on steady-state curves with various forms of steering linkages or yaw relaxation, it is shown that appreciable creep forces, with corresponding energy dissipation, are generated on curve transitions with variable curvature. As a measure of comparison with the above, the application of freely rotating wheels in a passive bogie is also considered. In order to overcome the inherent limitations associated with a passively stabilized solid-axle wheelset, two alternative solutions are considered: first, active stabilization of bogies with conventional wheelsets with reductions in primary yaw stiffness and secondly, active guidance of bogies with independently rotating wheels.

Recent Development in Active Steering of Railway Vehicles

Summary This paper presents the recent development on active steering for railway vehicles, and carries out a technical appraisal of different actuation schemes and control approaches. It brings together the latest research activities and findings for the full active steering techniques for rail vehicles with the solid-axle wheelsets, independently-rotating wheelsets and wheel-pairs without axles, but relevant work on passive and semi-active solutions is also briefly described. Potential benefits of the use of a combination of modern control technology and mechatronic approach are evaluated, and in particular solutions for the difficult design trade-off between the stability and the curving performance are presented. Various actuation configurations are discussed, and advantages and drawbacks of those schemes are investigated. The outline design using a number of control methods is analysed, and measurement requirement and state estimation techniques essential for implementation of the active steering schemes are also explored. In addition the issue of safety criticality is highlighted and a possible approach for developing fault-tolerant systems is proposed. Overall the paper provides an authoritative assessment of the major advances in actively-steered wheels and addresses outstanding critical issues.

NON-LINEAR KALMAN FILTER ESTIMATION FOR ACTIVE STEERING OF PROFILED RAIL-WHEELS

This paper presents a study of state estimation for active steering of profiled wheels. Fundamental characteristics of a solid-axle wheelset are explained and the potential benefits of active steering are discussed. The paper studies the non-linearity of the wheelset caused by profiled wheel-rail contact surfaces and develops a recursive non-linear Kalman filter to provide reliable and accurate estimations of the wheelset state. Real wheel and rail profiles are used in the study and a non-linear model is developed to represent the wheelset. Computer simulations are used to verify the design and assess its performance.

Mechatronic solutions for high-speed railway vehicles

Abstract This paper presents recent developments in the study of active steering for railway wheels. It demonstrates the potential benefits from this form of active control and studies what could be achieved when modern control techniques are used on the vehicles via mechatronic components. The study is based on a mechanically simplified vehicle and active control strategies for three wheelset/wheel-pair configurations are studied, which are solid axle wheelset, independently rotating wheelset and directly steered wheel pairs. Various mechatronic vehicle configurations are discussed and different control schemes are presented. Two key performance requirements, i.e. the curving performance of the wheelset and ride quality of the vehicle, are assessed for all proposed schemes. Finally, actuation requirement is also investigated.

Mechatronic Solutions for High Speed Railway Vehicles

This paper presents recent developments in the study of active steering for railway wheels. It demonstrates the potential benefits from this form of active control and studies what could be achieved when modem control techniques are used on the vehicles via mechatronic components. The study is based on a mechanically simplified vehicle and active control strategies for three wheelset/wheel-pair configurations are studied, which are solid axle wheelset, independently rotating wheelset and directly steered wheel pairs. Various mechatronic vehicle configurations are discussed and different control schemes are presented. Two key performance requirements, i.e. the curving performance of the wheelset and ride quality of the vehicle, are assessed for all proposed schemes. Finally actuation requirement is also investigated.

Modal Controllers for Active Steering of Railway Vehicles with Solid Axle Wheelsets

This paper presents the development of a modal control strategy for the active steering of solid axle railway vehicles and reveals benefits of actively stabilising the wheelsets of a railway vehicle. A modal decomposition is applied to a 2-axle railway vehicle to de-couple its body lateral and yaw motions and hence to allow more detailed analysis of the vehicle behaviour and more robust design of active controllers. Independent controllers for the two motions are developed based on the two de-coupled modes. Parameter variations such as creep coefficients and wheelset conicity are taken into account in the design process to guarantee a robust design. The study shows that, compared to a passive vehicle, the vehicles with actively steered wheelsets not only perform much better on a curved track, but also improve the ride quality on straight track. Computer simulations are used in the study to verify the development of the controllers and assess the system performance with the control scheme proposed.

Curving simulation and stability of a creep-controlled wheelset for high speed rail-vehicles

Higher travel speeds of rail vehicles will be possible by developing sophisticated top performance bogies having creep-controlled wheelsets. In this case the torque transmission between the right and the left wheel is realized by an actively controlled creep coupling. To investigate hunting stability and curving capability the linear equations of motion are written in state space notation. Simulation results are obtained with realistic system parameters from industry and various controller gains. The advantage of the „creep-controlled wheelset" is discussed by comparison the simulation results with the dynamic behaviour of the special cases „solid-axle wheelset" and „loose wheelset" (independent rotation of the wheels). The stability is also investigated with a root-locus analysis.

State estimation for active steering of railway vehicles

Abstract This paper presents state estimation techniques for active control of two types of railway wheelset: a conventional solid-axle wheelset and one with independently-rotating wheels (IRW). It presents a linearised dynamic model with simulation results for straight and curved track, and then the Kalman-Bucy filter is introduced to show how some primary feedback variables which are needed for active control may be estimated.