Modelling and control of railway vehicle suspensions

This chapter uses a railway vehicle as an example of a mechanical dynamic system to which control can be applied in a manner that yields significant benefits from an engineering and operational viewpoint. The first part describes the fundamentals of railway vehicles and their dynamics: the normal configuration, the suspension requirements, how they are modelled and an overview of the types of control concept that are currently applied or under consideration. The second part provides a case study of controller design issues

H∞ voltage control of a direct high-frequency converter

Providing a secure power network is a demanding task but as network complexity is expected to grow with the connection of large amounts of distributed generation so the problem of integration, not just connection, of each additional generator becomes more protracted. A fundamental change to contemporary network architectures may eventually become necessary and this will provide new opportunities for power electronic converters to deliver advanced management and new power flow control features. Direct resonant converters (Dang 2005), could be used in novel devices such as the Active Transformers (Garlick 2008). The key to the successful exploitation of these devices will be their versatility, controllability and cost efficiency

LQG control for the integrated tilt and active lateral secondary suspension in high speed railway vehicles

The paper deals with the tilt control performance of high speed railway vehicles. In particular it discusses the integration of active tilt control with an active lateral secondary suspension solution using LQG control design. The tuning of the weighting matrices of the LQG controller, for the aforementioned dual-actuator system, is accomplished using Genetic Algorithms based upon minimizing given tilting performance metrics. Issues of vehicle modeling and practical tilting performance are also included. The solution is validated via appropriate simulations and comparison with a conventional (tilt-only) precedence controller which provides a performance benchmark for the local control strategie

Active suspensions: a reduced-order H∞ control design study

This paper studies order reduction issues for a vehicle active suspension system throughout its modelling, H-infinity controller design and controller refinement. Computer simulations demonstrate that an H-infinity controller for a full active suspension can be significantly reduced to nearly one third of its full order, while the active suspension performance is only slightly degraded. As a by-product, this paper also provides an explicit algorithm for reduced H-infinity control for singular and non-singular continuous-time systems

Optimised sensor configurations for a Maglev suspension

This paper discusses a systematic approach for selecting the minimum number of sensors for an Electromagnetic levitation system that satisfies both deterministic and stochastic performance objectives. The controller tuning is based upon the utilisation of a recently developed genetic algorithm, namely NSGAII. Two controller structures are discussed, an inner loop classical solution for illustrating the efficacy of the NSGAII tuning and a Linear quadratic gaussian structure particularly on sensor optimization

Optimised sensor configurations for a MAGLEV suspension system

This paper discusses a systematic approach for selecting the minimum number of sensors for an Electromagnetic suspension system that satisfies both optimised deterministic and stochastic performance objectives. The performance is optimised by tuning the controller using evolutionary algorithms. Two controller strategies are discussed, an inner loop classical solution for illustrating the efficacy of the evolutionary algorithm and a Linear Quadratic Gaussian (LQG) structure particularly on sensor optimisation

Modelling requirements for the design of active stability control strategies for a high speed bogie

The paper presents the findings of a study on active stability control and simulation for a railway bogie vehicle. For control design a planview partial railway vehicle model is described. This is a simplified model derived from research experience and appropriate modelling, and a frequency domain analysis illustrates the problems associated with system instability. A multi-body dynamics software, SIMPACK1, is used to generate a detailed non-linear full vehicle model for simulation and control assessment. Model order reduction methods, both empirically and analytically based, are used to simplify the linear model generated from SIMPACK for further system analysis and control designs based upon the complex model. Comparisons between the simplified plan-view model and the exported reduced-order model are presented

Recent results in tilt control design and assessment of high-speed railway vehicles

Active tilt control is a well-established technology in modern railway vehicles, for which currently used control approaches have evolved in an intuitive matter. This paper presents work on a set of novel strategies for achieving local tilt control, i.e. applied independently for each vehicle rather than the whole train precedence approach that is commonly used. A linearized dynamic model is developed for a modern tilting railway vehicle with a tilt mechanism (tilting bolster) providing tilt below the secondary suspension. It addresses the fundamental problems associated with straightforward feedback control, and briefly discusses the current industry norm, which employs command-driven with precedence strategy. Two new advanced schemes are proposed, a model-based estimation approach, and an optimal LQG-based approach, and compared to the command-driven with precedence. The performance of the control schemes is assessed through simulation using a new proposed assessment method

Integrated tilt and active lateral secondary suspension control

This paper describes a theoretical study on the integration of tilt and active lateral secondary suspension control issues relate to the system performance requirements, controller assessment approaches, modelling process and dynamics interaction analysis. Two dual-actuator control system configurations with classical decentralized controllers are presented. The work aims to improve the performance of a tilt controller based only upon local vehicle measurements by integrating the lateral active secondary suspension with the roll (tilt actuator). The effectiveness of the integrated control is illustrated via simulations and comparisons with previous modified nulling tilting control as well as the commercial precedence equivalent

The architecture and control of large power networks with distributed generation

This paper briefly summarises the evolution of transmission and distribution networks since the late 19th century, and explains that the introduction of significant amounts of distributed generation may bring about a future fundamental change to the network architecture. Providing a secure power network is a demanding task, but as network complexity is expected to grow with the connection of large amounts of distributed generation, so the problem of integration, not just connection, of each successive generator becomes more protracted. A fundamental change to the network architecture may eventually become necessary and a new architecture, perhaps based on power cells, containing generation, energy storage and loads has been proposed by some researchers. This paper describes a novel power cell interface. It makes the case for the conventional power transformer to be replaced by an Active Transformer, the objective being to provide a more controllable, flexible and robust connection that will facilitate greater network management and business opportunities, and new power flow control features. The Active Transformer design is based on an a.c. link system described by Thomas Lipo in 1986 and an a.c.-a.c. high-frequency direct converter design demonstrated by Dang in 2006. It consists of a resonant, supply-side converter, a high frequency transformer and a resonant, load-side converter. This paper describes a model of the Active Transformer, built in Simulink®, and presents the results of simulations that demonstrate its action to control current in a resistive load