A study on optical sensors orientation for tomography system development

This paper describes the investigation of optical sensors performance towards the development of optical tomography system. The orientation of the transmitters has been set from 0o until 180o and then the receiver’s responses were analyzed. Hence, sensors capabilities were tested further by placing blockage object in between the transmitter and receiver and the effect of this arrangement were observed. Finally, new designs of sensor jig were introduced based on the results achieved. Copyright © 2012 IFS

ASSESSING THE ENERGY EFFICIENCY OF RAILWAY VEHICLES WITH WHEELSET ACTIVE CONTROL

Energy consumption in electric locomotives is principally the power consumed in traction motors. In order to reduce this energy consumption, the motion resistances of the train need to be reduced. These resistances include aerodynamics; inertial and grade forces; curving resistance; and bearing and wheel/rail friction. Though many factors such as gradient resistance cannot be modified, if a control system is included, curving resistance can be minimised by reducing the energy losses in the contact patches between wheel and rail. Therefore, operational practices could be modified in order to obtain the most appropriate wheelset attack angle between wheel and rail, and appropriate train speed. One solution is to implement a steering control system. The function of this control system is to monitor and control the wheelset lateral displacement or the attack angle of the wheelset. This could reduce the energy dissipated at the contact points between wheel and rail, consequently reducing the energy consumed by traction motors in railway vehicles. Therefore, the work presented in this thesis aims to design and develop a control method for combined vehicle traction and wheelset active steering control systems and to assess the energy efficiency of a rail vehicle under typical operational conditions. In order to achieve these aims, two dynamic models of a typical railway vehicle have been developed in MATLAB and Simulink. The first model comprises the electrical traction and mechanical system passive system). The second model includes the passive and the wheelset active steering control system (active system). These models are used to determine the relationship between traction energy consumption and the energy dissipated in the contact points between wheel and rail, and to compare the passive steering system to the wheelset active steering control system, determining the possibilities for energy saving. In order to assess the influence of the wheelset active steering control on the relationship between wheel and rail contact forces and traction power a series of deterministic track features are set comprising curve radii with different cant deficiencies and wheel conicities. Also a typical track profile from Leeds to Hull is used. From these simulations, the traction energy consumption, energy dissipated at the contact patches, and energy consumed by the steering actuators are calculated. Statistical analyses are used to understand the relationship between the traction power and wheelset motion dynamics (lateral displacement and attack angle). The active vehicle model scheme is used to investigate the improvement of the energy efficiency of a railway vehicle using active steering. The wheelset active steering control system analysis shows whether different combinations of vehicle speed, wheelset conicity and track curve radius lead to a reduction, no reduction, or an increase intraction power consumption. The probability of high power consumption under different conditions is assessed to ensure that it is reduced wherever possible. The ability of a forecasting model to predict the traction power consumption behaviour of railway vehicles from the wheelset motion dynamic is assessed. Findings show that the overall prediction accuracy is fairly similar to the power measured from the passive vehicle running on a track from Leeds to Hull. However, the algorithm does not perform effectively for the deterministic track features. Finally, the benefits of implementing wheelset active steering control systems in terms of the mitigation of contact forces between wheels and rails and how this mitigation influences traction energy consumption are evaluated to determine under what conditions energy can be saved

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

Mechatronic guidance of rail vehicles through switches and crossings to enable vehicle-based switching

The research presented in this thesis demonstrates the theory that a mechatronic rail vehicle could be used on conventional switches and crossings (S\&Cs) to reduce wear. Railway track switches withstand high vertical and lateral forces leading to wear and damage. This necessitates a disproportionately high level of maintenance of over 10 \% of total maintenance costs, despite accounting for less than 0.1 \% of the network length. Mechatronically-guided rail vehicles are of paramount importance in addressing the increasing interest in reducing wheel-rail wear across the network and improving guidance and steering. Conventional passively-guided rail vehicles are limited by the mechanical constraints of the suspension elements. Currently, a typical rail vehicle suspension needs to be sufficiently stiff to stabilize the wheelsets while being complaint enough to negotiate curved track profiles. The suspension is therefore a compromise for the contradictory requirements of curving and stability. In mechatronic vehicles, actuators are used with the conventional suspension components to provide pseudo stiffness or damping forces needed to optimise a vehicle for a wide variety of scenarios, which can be positive or negative. This means that the vehicle is not reliant on a sub-optimal combination of passive components. Previous research in the area of mechatronic rail vehicles has shown the performance improvement in different straight or curved track profiles compared to a conventional vehicle. In this thesis, three vehicle configurations discussed previously in the literature, are evaluated on several different track profiles. These are the secondary yaw control (SYC), actuated solid-axle wheelset (ASW) and driven independently-rotating wheelsets (DIRW) steering mechanisms. The vehicle models are implemented in a multi-body simulation software Simpack to obtain high fidelity simulations that are comparable to a real rail vehicle. The DIRW vehicle showed the best performance in terms of reduced wear and minimal flange contact and was therefore chosen for studying its performance on a conventional S\&C. The DIRW vehicle was simulated on a C switch which is the most common on the UK mainline and on a high speed H switch. The results show that the DIRW vehicle gives a significant reduction in wear and reduces flange contact on the through and diverging routes of both S\&Cs. This proves the theory that active vehicles could be used to reduce impact forces at conventional S\&Cs. This could be an intermediate step towards a longer term vision of having a track switch without any moving parts where the switching is vehicle-based instead of track-based. Ultimately, if active elements on the vehicle could fully control the route while the track switch was completely passive i.e. had no moving parts, the reliability of the railways as a transport system would increase significantly. The technology could be combined with electronically-coupled vehicles which could form longer trains on busier routes and decouple to serve intermediary routes

Laptop cooling pad temperature monitoring system

Cooling pads are commonly used to reduce temperature of laptop to avoid overheating problem. However, existing cooling pads are prone to various limitations: fixed voltage in the hardware component, inaccurate temperature readings and lacked of computer-based temperature monitoring functions. In this paper, a laptop cooling system with multivoltage fan speed controller using real-time processor temperature readings is proposed. A graphical user interface (GUI) and color coded LEDs are also implemented to provide visual inspection of the temperature values captured from the laptop. The temperature values are displayed in graph and tabular form. The performance of the proposed cooling pad with computer-based monitoring application is evaluated against two other types of existing cooling pad systems. The experiments have shown that the temperature values can be monitored clearly with the proposed GUI. More importantly, the proposed cooling pad system has the potential to achieve lower temperature faster than the rest of the existing cooling pad systems

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 (S&C), 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 MBS models of mechatronic rail vehicles of three different mechanical configurations - secondary yaw control (SYC), actuated solid-axle wheelset (ASW) 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 S&Cs. 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 independentlyrotating wheelsets (IRWs) where each wheel has an integrated ’wheelmotor’. This work demonstrates the theory that mechatronic rail vehicles could be used on conventional S&Cs. 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

Semi-active control for independently rotating wheelset in railway vehicles with MR dampers

This thesis presents details of an investigation of a controller for MR damper in the implementation of semi-active control, for primary suspensions of the independently rotating railway vehicles. This research focuses on using MR damper and it addresses on three main aspects when designing semi-active control systems for this application.One aspect is magnetorheological dampers categorised as a controllable fluid damper which can reversibly change from a flowing viscose fluid to semi-solid viscose fluid. The second aspect is the controllable yield strength can change in a millisecond by inducing an electric or magnetic field. Third aspect is MR damper is cheaper than actuators which are usually use in full active controllerThis research is a combination of a lookup table based on the inverse MR damper model to control the current input (to the MR damper) from required force and relative velocity of the device. The MR damper produces the desired force as precisely as possible. However, it is not possible to have precise knowledge of MR parameters and it is also difficult to account for the hysteresis present in MR dampers in the lookup table. Therefore, an additional local PI feedback controller is also used to improve the robustness for the MR control.As the main result, this study provides a comparison between semi-active controller with the use of MR damper and a full active controller system. The results show semi-active controller with the use of MR damper performed as good as full active controller. However semi-active control systems with MR dampers offer an overall efficiency and robustness when compared to the full active control system. Also, this system delivers comparable performance with the benefit of increased reliability and lower cost.In order to assess the developed system comprehensively, a two–axle vehicle model and a full bogie vehicle model are both evaluated individually in the study.The performance and robustness assessments of the developed semi-active controller with the full active control system are evaluated with the use of both two–axle vehicle model and the full bogie vehicle model with different operational track features such as curved track and straight track with lateral irregularities with various travel speeds.This study designed and developed a semi-active control systems with use of MR damper in primary suspension for independent rotation wheelsets in railway vehicles. Computer simulation results verified the suggested semi-active control is able to provide required stability and guidance control for independently- rotating wheelsets. Also, the result performed as well as full active control with the advantage of utilizing a lower cost device for semi-active control rather than an expensive actuator for full active control