T. X. Mei

Control and monitoring for railway vehicle dynamics

Over the last twenty to thirty years, railway vehicle dynamics has changed from being an essentially mechanical engineering discipline to one that is increasingly starting to include sensors, electronics and computer processing. This paper surveys the application of these technologies to suspensions and running gear, focused upon the complementary issues of control (which has been reviewed within Vehicle System Dynamics previously) and monitoring (which has not previously been reviewed). The theory, concepts and implementation status are assessed in each case, from which the paper identifies the key trends and concludes with a forward look at what is likely to develop over the next years.

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.

Active stability control strategies for a high speed bogie

Abstract This paper presents a comparison of control algorithms for actively stabilised wheelsets on high speed railway vehicles. Both intuitively derived classical strategies and modern optimal strategies are considered. Computer simulations are used to assess and compare the performance of the strategies in terms of their ability to provide stability across a range of operating conditions, for a range of parameter uncertainty and also in terms of their actuator requirements. Actuator models are also developed, not only to properly assess the impact of actuator dynamics on the active stability system performance, but also to further quantify and refine the actuator requirements needed to implement the system practically. The concept has been implemented practically on a full size vehicle and some preliminary experimental results are included. Although the paper concentrates upon stability control, some observations are included regarding the integration of steering controllers.

Robust control for independently rotating wheelsets on a railway vehicle using practical sensors

This paper presents the development of H/sub /spl infin// control strategy for the active steering of railway vehicles with independently rotating wheelsets. The primary objective of the active steering is to stabilize the wheelset and to provide a guidance control. Some fundamental problems for active steering are addressed in the study. The developed controller is able to maintain stability and good performance when parameter variations occur, in particular at the wheel-rail interface. The control is also robust against structured uncertainties that are not included in the model such as actuator dynamics. Furthermore the control design is formulated to use only practical sensors of inertial and speed measurements, as some basic measurements required for active steering such as wheel-rail lateral displacement cannot be easily and economically measured in practice.

Condition monitoring of rail vehicle suspensions based on changes in system dynamic interactions

A novel scheme for the fault detection and condition monitoring of vehicle suspensions is presented in this study. The new technique exploits the dynamic interactions between different vehicle modes caused by component failures in the system, leading to a simple but effective solution. Compared with many model-based fault detection techniques, the proposed technique does not require complex mathematical models of the system and it overcomes potential difficulties associated with nonlinearities and parameter variations in the system. The use of inexpensive inertial sensors and ease of tuning make the practical implementation of the proposed scheme straightforward. A conventional railway vehicle is used in the study to illustrate the basic ideas as well as the effectiveness of the novel fault detection method, although the general principle is applicable to other systems.

Combined Active Steering and Traction for Mechatronic Bogie Vehicles with Independently Rotating Wheels

The benefits of substituting the conventional solid wheelset by independently rotating wheels (IRW) in actively steered trailed railway vehicles have already been presented in many works. If a traction system is included in this kind of vehicle it will interact strongly with the active steering system. This paper investigates how traction and active steering systems can be combined in an IRW bogie to produce a good curving performance. The combined steering and traction control concepts developed are implemented in simulation models and validated against a conventional passive vehicle. # 2004 Elsevier Ltd. All rights reserved.

Concepts and prospects for actively controlled railway running gear

As active suspension control is becoming an established technology for railways, it is time to look forward to further extensions of the basic concept, especially its application in controlling the wheels and wheelsets of rail vehicles. This article reviews the background to the subject, including an identification of basic configurations and technology options, before providing a summary of known concepts and the corresponding control strategies. The final section speculates upon the longer-term trends, in particular, to suggest what will be the overall impact upon suspension design.

A model-less technique for the fault detection of rail vehicle suspensions

This paper presents a novel method for the fault detection and condition monitoring of rail vehicle suspensions. The proposed technique takes advantage of the vehicle (suspension) configurations that are often symmetrical, and explores the additional dynamic interactions between different motions of a bogie or body caused by the failure of suspension components. The basic principle of the proposed detection method is presented and the interactions due to suspension fault conditions are analysed using a conventional two-axle bogie. Side-view models of a bogie vehicle are used in the study to demonstrate the effectiveness of the novel method in detecting damper faults in the suspensions. Both linear and bi-linear dampers are studied.

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.

Practical Strategies for Controlling Railway Wheelsets Independently Rotating Wheels

This paper presents the development of an active control strategy for railway vehicles with independently rotating wheels. The proposed control scheme is intuitively formulated with a simple control structure and adaptiveto vehicle speed. It does not require basic guidance measurements (e.g., wheel-rail deflection and angle of attack) that are expensive and impractical to implement. Speed sensors are used to measure the relative rotational speed of the two wheels on a same axle and sensors are also used to measure the relative yaw velocity of the wheelset and the body it is connected. Both curving performance and passenger ride comfort of the actively controlled vehicle are compared with that of a typical passive vehicle and an optimal control scheme.