Optimal handling and fault-tolerant speed regulation of heavy haul trains

Heavy haul trains are used to transport mineral resources from inland mines to harbours in South Africa. It is believed that the cost is less with a larger load per car or per train. This has resulted in the use of long heavy haul trains. The increase in train length has posed unprecedented technical challenges. For heavy haul trains, energy consumption, running time and in-train forces between neighbouring cars are of much concern to transportation corporations. The objective of the study is to find optimal driving methodologies for the implementation of a desired speed profile with energy consumption and in-train forces considered. Firstly, three control strategies are proposed in this study for train handling. In view of the characteristics of traditional pneumatic braking systems and the new Electronically Controlled Pneumatic (ECP) braking systems, a simulation study of optimal open loop controllers was undertaken. The result shows that the ECP braking systems demonstrate superb performance compared with pneumatic braking systems, especially together with independent distributed power (iDP) control. Thus, the main focus of the study was the control of heavy haul trains equipped with ECP braking systems. It is shown that there are redundancies in designing an open loop controller. An optimization procedure is applied to schedule cruise control by taking the in-train forces into initial design consideration. Optimal open loop scheduling presents a better starting point for a closed-loop controller design. A type of linear quadratic regulator (LQR) controller with state feedback is simulated to verify the above result. However, the closed-loop control law is designed based on full state feedback, which is not practical since not all the states can be measured. An observer could be designed to supplement the LQR controller if partial states are measured. This is, however, not the approach taken in this study. Instead, the application of output regulation of nonlinear systems with measured output feedback to the control of heavy haul trains is considered. This approach to design is practically feasible and manageable, and by its nature, is also easily integrable with human drivers. In this study, the existing result of output regulation of nonlinear systems is extended. The output regulation problem of nonlinear systems with measured output feedback is formulated in this study and solved for the local version and global version. For its application to train control, some application issues are discussed. Based on the proposed theory, a speed regulator for train control is designed. Simulation results show its applicability. Lastly, this study concentrates on the fault-tolerant capacity of the speed regulator. Two kinds of fault modes are considered. Fault detection and isolation for the sensor fault and braking system fault are exploited. Controller redesign is also given. Simulation results show that such a speed regulator has a fault-tolerant capacity to the corresponding faults.Thesis (PhD)--University of Pretoria, 2007.Electrical, Electronic and Computer EngineeringPhDUnrestricte

Adaptive Control Design and Evaluation for Multibody High-speed Train Dynamic Models

In this paper, the adaptive tracking control problem is investigated for multibody high-speed train dynamic model in the presence of unknown parameters, which is an open adaptive control problem. A 4-car train unit model with input signals acting on the 2nd and 3rd cars and output signals being the speeds of the 1st and 3rd cars is chosen as a benchmark model, in which the aerodynamic resistance force is also considered. To handel the nonlinear term, the feedback linearization method is employed to decompose the system into a control dynamics subsystem and a zero dynamics subsystem. A new and detailed stability analysis is conducted to show that such a zero dynamic system is Lyapunov stable and is also partially input-to-state stable under the condition that the speed error between the 1st and 3rd cars is exponentially convergent (to be ensured by a nominal controller) or belongs to the L1 signal space (to be achieved by a properly designed adaptive controller). The system configuration leads to a relative degree 1 subsystem and a relative degree 2 subsystem, for which different feedback linearization-based adaptive controllers and their nominal versions are developed to ensure the needed stabilization condition, the desired closed-loop system signal boundedness and asymptotic output speed tracking. Detailed closed-loop system stability and tracking performance analysis are given for the new control schemes. Simulation results from a realistic train dynamic model are presented to verify the desired adaptive control system performance

Optimal cruise control of heavy-haul trains equipped with electronic controlled pneumatic brake systems

In this study a closed-loop cruise controller to minimise the running costs of the heavy-haul train is proposed. The running costs of a heavy-haul train are dependent on its travelling time, maintenance costs and energy consumption during the trip. The Coallink train with the new train technologies, Distributed Power (DP) traction and Electronically Controlled Pneumatic (ECP) brake system, is the centre of the study. A literature study on existing train control, both passenger and heavy-haul trains, is carried out to build up a knowledge base. Many different techniques for train handling were observed, their features in relation to heavy-haul ECP trains are discussed. From these backgrounds, a comprehensive longitudinal train model is proposed and successfully validated with real-life data from Spoornet. In the model, both static and dynamic in-train forces are studied, as well as energy consumption. This is possible by modelling each locomotive and wagon as an individual unit. The equations of motion for the train with coupled units and additional non-linearities, such as traction power limits, are considered. An open-loop controller for maintaining equilibrium velocity is designed. During transient velocity changes, a transient controller for calculating the required additional acceleration and deceleration is designed and validated. Because locomotive traction settings are only available in discrete notches, quantisation conversion from force into notches results in input chattering. In addition, during brake to traction transitions, the locomotives receive a sudden traction demand which results in spikes in in-train forces. To avoid these problems, input filtering is performed for these inputs. Closed-loop controllers based on LQR method, optimised for in-train forces, energy consumption and velocity regulation respectively, are designed and compared. To overcome the communication constraints, a fencing concept is introduced whereby the controller is reconfigured adaptively to the current track topology. Different train configurations in terms of availability of additional control channels for both traction and braking are compared, as well as their effects on dynamic and static in-train force. These configurations are unified, distributed and individual traction and brake controls. The results from these different configurations are compared to recorded train data and given in this study. From the results, it is found that the closed-loop controller optimised for in-train force is able to provide the best overall improvement out of the three controllers.Dissertation (MEng)--University of Pretoria, 2007.Electrical, Electronic and Computer EngineeringUnrestricte

Strategies for maintenance management of railway track assets

M.Ing. (Engineering Management)Abstract: Population growth and environmental issues are revitalizing the railway sector in a tremendous way. An increase in frequency of passenger traffic and rising loads of freight trains has an impact on dynamic railway track properties and components thereof. The challenge from the railway fraternity is to rise to the challenge by ensuring a safe, reliable and affordable mode of transport. The purpose of this research is to investigate the capacity needed to meet demand by maintaining the track components of the railway infrastructure cost effectively. The railway track is the most critical in terms of safety, influence on maintenance costs, availability and reliability of the train service. Profillidis (2012) highlights the fact that track maintenance expenses represent a significant percentage of total railway infrastructure expenses. In literature, different maintenance strategies, approaches and concepts are discussed in light with arguments raised by different scholars and researchers. The main research methodology utilised was the case study on maintenance strategies from different countries where data was mostly available. The reason for the chosen method was to standardise the research method across different countries as this made it easy to obtain the findings and arrive at recommendations of the research. The broader findings from different maintenance strategies were that the track maintenance approach still has to evolve from working in silos to working in a system that acknowledges that decisions taken from other departments can affect the quality of maintenance in future. The deterioration of the track system is mostly affected by the initial quality of the railway track after commissioning due to workmanship and track design, maintenance approach, type of rolling stock tonnages, speed of rolling stock, and environmental related issues. Design phase of the track acknowledges the systems thinking approach for quality and structural integrity. However, more can still be done to adopt approaches that foster inter-departmental coordination in the maintenance phase of the railway track asset lifecycle. Transnet faces a challenge of fulfilling its obligation by providing quality and cost effective maintenance to increase the reliability, affordability, availability and safety of its infrastructure with the ever-increasing freight volumes. The traditional approach of maintaining railway track assets does not bring in required outcomes that ensure high quality and cost effective maintenance as required by high intensity asset utilisation. Data collected from the..

Braking penalized receding horizon control of heavy haul trains

Incorporated with a receding horizon control (RHC) approach, a penalty method is proposed to reduce energy wasted by braking in a heavy haul train’s operation. The train’s practical nonlinear model is linearized to design the RHC controller. This controller is then applied to the train practical nonlinear dynamics and its performances are analyzed. In particular, the main focus in this study is on the brake penalty’s impact on the train performances. Meantime, a fence method is presented to tackle two issues. The first one is that all the cars in a train cannot be controlled individually due to limit of available transmission channels for control systems in a long train. The other one is that the RHC approach suffers from heavy computation and memory load. Simulations verified that the brake penalty presented in the design can reduce a train’s energy consumption and intrain forces remarkably without sacrificing the train’s velocity tracking performance. Simulations also verified that the fence method is essential to reduce the related computation load when the RHC approach is applied to a long heavy haul train. Further, it is demonstrated that the fence method can effectively shorten computation time and reduce memoryhttp://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=6979hb2014ai201

Adaptive position tracking control of high-speed trains with piecewise dynamics

This paper addresses the adaptive position track-ing control problem for high-speed trains with time-varying resistances and mass in the motion dynamics. To handel these time-varying parameters with piecewise constant characteris-tics, a piecewise constant model with unknown parameters is in-troduced for different train operation conditions. An integrated adaptive controller structure is constructed to have the capacity to achieve plant-model matching with known parameters and complete system parametrization with unknown parameters, which is desirable for adaptive tracking control. For the train position tracking requirement, the reference model system is speci?cally chosen. Stable adaptive laws are designed to update the adaptive controller parameters in the presence of the unknown piecewise constant system parameters. Closed-loop stability and asymptotic state tracking are proved. Simulation results on a high-speed train model are presented to illustrate the desired adaptive position tracking control performance

Railway Research

This book focuses on selected research problems of contemporary railways. The first chapter is devoted to the prediction of railways development in the nearest future. The second chapter discusses safety and security problems in general, precisely from the system point of view. In the third chapter, both the general approach and a particular case study of a critical incident with regard to railway safety are presented. In the fourth chapter, the question of railway infrastructure studies is presented, which is devoted to track superstructure. In the fifth chapter, the modern system for the technical condition monitoring of railway tracks is discussed. The compact on-board sensing device is presented. The last chapter focuses on modeling railway vehicle dynamics using numerical simulation, where the dynamical models are exploited

Future heavy duty trucking engine requirements

Developers of advanced heavy duty diesel engines are engaged in probing the opportunities presented by new materials and techniques. This process is technology driven, but there is neither assurance that the eventual users of the engines so developed will be comfortable with them nor, indeed, that those consumers will continue to exist in either the same form, or numbers as they do today. To ensure maximum payoff of research dollars, the equipment development process must consider user needs. This study defines motor carrier concerns, cost tolerances, and the engine parameters which match the future projected industry needs. The approach taken to do that is to be explained and the results presented. The material to be given comes basically from a survey of motor carrier fleets. It provides indications of the role of heavy duty vehicles in the 1998 period and their desired maintenance and engine performance parameters

Development of an optimal operation approach in the MPC framework for heavy-haul trains

An operation control approach for heavy haul trains to optimize their performance, including operation safety, service quality and energy consumption, is proposed. Following a model predictive control method, the controller is capable of scheduling a train to operate optimally during a long section of the rail track. In the cost function, two penalty factors are presented, one for the braking forces and one for coupler damping effects. The penalty for braking forces is employed to reduce energy waste incurred by braking. The penalty for coupler damping is introduced to alleviate the cyclic vibration of couplers, which link adjacent cars in the train. The damping penalty is also expected to reduce energy wasted by coupler damping and corresponding maintenance/replacement cost of the dampers. In addition, the weight of the velocity tracking term in the objective function is modified to vary dynamically according to the train’s velocity to improve the train’s overall performance. Simulations verify the effectiveness of the proposed control approach. Discussions over the impacts of the two penalty factors and dynamic weight method are provided together with some suggestions on their applications.http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=6979hb201

Adaptive Fault-Tolerant Control of A Two-car High-speed Train Model with Inter-car Flexible Link and Traction Actuator Failures

This paper studies the adaptive fault-tolerant tracking control problem for the high-speed trains with intercar flexible link and traction actuator failures. This study is focused on a benchmark model which, as a main dynamic unit of the CRH (China Railway High-speed) train, is a two-car dynamic system with a flexible link between two cars, for which the input acts on the second car and the output is the speed of the first car. This model is under parameter uncertainties and subject to uncertain actuator failures. For such an underactuated system, to ensure the first car tracking a desired speed trajectory, a coordinate transformation method is employed to decompose the system model into a control dynamics subsystem and a zero dynamics subsystem. Stability analysis is conducted to show that such a zero dynamic system is Lyapunov stable and is partially input-to-state stable. An adaptive fault-tolerant control scheme is developed which is able to ensure the closedloop system signal boundedness and desired speed tracking, in the presence of the unknown system parameters and actuator failures. Simulation results from a realistic train dynamic model are presented to verify the desired adaptive control system performance