Wheel Slide Protection System Research Articles

A 4-Phase Combined Adhesion Threshold Algorithm for Wheel Slide Protection Systems in Rail Vehicles

The wheel slide protection control system for rail vehicles plays a crucial role in ensuring a consistent braking performance in all operating environments, making it a vital factor in the safety and efficiency of rail transportation. In this paper, a hybrid approach to wheel slide protection control is presented, which combines the rule-based control strategy and the model-based control methods using adhesion force estimation. Model-based control usually relies on mathematical models to characterize the vehicle dynamics, requiring online estimators to be designed or extra sensors to be added for practical application. Rule-based control operates on predefined rules and thresholds and the available data from vehicles in service. A comparative test was conducted between the traditional rule-based control strategy and the proposed combined control strategy using a semi-physical simulation test bench. The performance differences of the control strategies were analyzed from two perspectives: adhesion utilization and air consumption. It was observed that among the traditional 2-phase, 3-phase, 4-phase and the optimized 4-phase combined control method, the combined control strategy has the best adhesion utilization and the traditional 4-phase control strategy has the least air consumption.

HIL testing of wheel slide protection systems: criteria for continuous updating and validation

Assessment of railway wheel slide protection (WSP) systems involves the execution of complex experimental activities that are quite expensive and time-consuming, since they involve the physical reproduction of degraded adhesion conditions on a real railway line. WSP is devoted to regulating applied braking forces to avoid excessive wheel sliding in case of degraded adhesion conditions between wheel and rail. WSP must be also compliant to safety specifications related to assured braking performances and consumed air. Hardware in the loop (HIL) testing offers an affordable and sustainable way to accelerate these activities optimizing cost, duration and safety of experimental activities performed online. HIL test rigs are subjected to continuous updates, customization and natural ageing of their components. This work investigates the criteria that can be adopted to assure a continuous monitoring and validation of a real WSP test rig, the Italian test rig of Firenze Osmannoro.

Estimating the Damage of Railway Carriage Wheels Equipped with Disc Brakes

The aim of this paper is to estimate the damage of railway carriage wheels caused by lock-up braking. First, we investigate the typical characteristics of wheel-rail contact including the parameters of contact patch, longitudinal creep and coefficient of adhesion. Then we show the current requirements concerning the wheel-slide protection systems and determine the points which should be reviewed. To predict the effect of the sliding phenomenon, material properties are needed, as well. Afterwards, a simplified thermal simulation is built to estimate where martensite formation may occur.

Wheel Slide Protection System for Rolling Stock Capable of More Effective Adhesion by Using Statistical Technique

The brake systems used in current railways utilize the tangential force (so called the adhesion force) acting upon rails and wheels for reducing speed. The tangential force is affected by conditions such as climate, contact surfaces of rails and wheels. It is difficult to keep the braking performance in the lower tangential force conditions which can frequently cause wheel slides. The wheel slide protection system (WSP) is one of the useful approaches used in many vehicles. However, existing WSPs control the braking forces based on the information induced only from rotational speed of the wheels. They do not optimally perform braking in response to the frequently changed tangential force. In this study, we propose the use of the value equivalent to the tangential force, which are estimated by using brake cylinder pressures during wheel slides. In addition, we propose a method which extracts the statistic feature about the tangential force from many braking test data. Furthermore, we set out a new WSP which can decide the action based on the effectiveness and the statistic feature about the tangential force. We carried out bench tests and the results of the test show the proposed WSP can keep higher deceleration than existent ones.

<b>Wheel Slide Protection System by the Use of the Tangential Force in the Macro Slip Area</b>

<b>Wheel Slide Protection System by the Use of the Tangential Force in the Macro Slip Area</b>

Modeling and Control of a Full-Scale Roller-Rig for the Analysis of Railway Braking Under Degraded Adhesion Conditions

Currently, braking on board subsystems such as wheel slide protection (WSP) devices almost totally control the longitudinal train dynamics. In particular, the vehicle safety highly depends on the study and the development of these systems, especially at high speeds and under degraded adhesion conditions. Usually, to save time and to avoid expensive on-track tests, the performances of braking subsystems are tested on full-scale roller-rigs. Nevertheless, the analysis of the subsystem behavior under degraded adhesion conditions is still limited to a few applications on roller-rigs because large slidings among the rollers and wheelsets produce severe wear of the rolling surfaces. This circumstance is not acceptable due to the effects on the maintenance costs (the rollers have to be turned or substituted), on the system dynamical stability and on the safety. In this paper, the modeling and control of an innovative hardware in the loop (HIL) architecture to test braking on board subsystems on full-scale roller-rigs is described. The new approach permits to reproduce on the roller-rig a generic wheel-rail adhesion pattern and, in particular, degraded adhesion conditions. The presented strategy is also followed by the innovative full-scale roller-rig of the Railway Research and Approval Center of Firenze-Osmannoro (Italy); the new roller-rig has been built by Trenitalia and is owned by SIMPRO. At this initial phase of the research activity, to effectively validate the proposed approach, a complete model of the HIL system has been developed. The complete numerical model is based on the real characteristics of the components provided by Trenitalia. The results coming from the simulation model have been compared with the experimental data provided by Trenitalia and relative to on-track tests performed in Velim, Czech Republic, with a UIC-Z1 coach equipped with a fully working WSP system. The preliminary validation performed with the HIL model highlights the good performance of the HIL strategy in reproducing on the roller-rig, the complex interaction between the degraded adhesion conditions and railway vehicle dynamics during the braking maneuver.

An innovative hardware in the loop architecture for the analysis of railway braking under degraded adhesion conditions through roller-rigs

Nowadays, the longitudinal train dynamical behaviour is almost totally controlled by braking on board subsystems, such as Wheel Slide Protection (WSP) devices. The study and the development of these systems are fundamental for the vehicle safety, especially at high speeds and under degraded adhesion conditions. Traditionally, the performance of braking subsystems is tested on full-scale roller-rigs, to save time and to avoid expensive on-track tests. However, the study of the subsystem behaviour under degraded adhesion conditions on roller-rigs is still limited to few applications since high slidings among rollers and wheelsets generate wear of the rolling surfaces. This event is not acceptable because of the effects on the maintenance costs (the rollers have to be turned or substituted), on the system dynamical stability and on the safety.In this work the authors present an innovative Hardware In the Loop (HIL) approach for testing braking on board subsystems on full-scale roller-rigs. The new approach permits the reproduction on the roller-rig of a generic wheel-rail adhesion pattern and, in particular, of degraded adhesion conditions. The described strategy is the same implemented on the innovative full-scale roller-rig, recently built by Trenitalia and owned by SIMPRO, in the Railway Research and Approval Center of Firenze-Osmannoro (Italy). To validate the proposed approach, a complete model of the HIL system has been developed; the results provided by the simulation model have been compared to the experimental data provided by Trenitalia and relative to the on-track tests performed in Velim, Czech Republic, with a UIC-Z1 coach equipped with a fully-working WSP system. The complete model is based on the real characteristics of the components provided by Trenitalia. The preliminary validation performed with the HIL model highlighted the good performance of the HIL strategy in reproducing on the roller-rig the complex behaviour of the degraded adhesion during the braking of a railway vehicle. The next steps of the research activity will be the implementation both of the controller and the virtual vehicle model on the real Firenze-Osmannoro roller-rig.

Hardware-in-the-Loop Simulation for a Wheel Slide Protection System of a Railway Train

Abstract A wheel slide protection (WSP) system of a railway train has the role of reducing excessive wheel slide from brake applications in situations where wheel/rail adhesion is temporarily impaired. The mechanism of the WSP is complex and is related to highly nonlinear dynamics of the train. Hardware-in-the-loop simulation (HILS) for the WSP system can test various dangerous braking conditions which are not possible in actual train tests, and help to find appropriate parameters of the WSP system. This paper presents a HILS unit for the WSP system, which is composed of an actual WSP unit, two actual dump valves, a dSPACE module, and a personal computer with Linux operating system. The dSPACE module simulates railway train dynamics in real-time, which includes dynamic models of wheelsets, bogies, a carbody, and a mechanical brake, and also a dynamic model for creep force generation in wheel/rail contacts. The validity of the HILS system for WSP control is demonstrated by ways of off-line simulation studies and experimental tests using the HILS unit for the Korean tilting train, Hanvit 200.

An innovative degraded adhesion model for multibody applications in the railway field

The simulation of the braking maneuver of a railway vehicle under degraded adhesion conditions is very important concerning the safety of railway operation. However, the implementation of a realistic friction law is comparatively difficult because of the complex and nonlinear behavior of the wheel-rail contact. Particularly under degraded adhesion conditions, very high creepages occur, which cause sliding in the contact. This sliding produces a high dissipation of energy, which has a cleaning effect on the rolling surfaces, and thereby strengthens the influence of the adhesion. In this work, this energetic criterion has been studied. The authors suggest implementing an innovative friction law to the simulation of railway multibody models with 3D multi-point contact detection algorithms. As a benchmark case, the braking of a coach equipped with a Wheel Slide Protection (WSP) system is simulated. The results are compared with experimental data available from previous testing activities by Trenitalia. The new friction law provides to match the experimental reference results and to carry out simulated braking tests, including the working WSP system, which comply with the current regulations (Railway applications, braking, wheel slide protection, UNI EN 15595, 2009).

Simulation of Wheel Slide Protection System for Railway Vehicles

Computer simulation was used to study WSP (Wheel Slide Protection) system in this paper. The model of WSP system was built. Simulation model can avoid real vehicle tests or laboratory bench which will cost a lot of time and expenses. The WSP system model was composed of pneumatic model, mechanical model and control model. Three models were connected with each other and formed a closed loop system. The result shows that the simulation model has most characteristics of WSP system. The model can be used in the study of WSP system instead of the real system.

Field investigations into the adhesion recovery in leaf-contaminated wheel–rail contacts with locomotive sanders

Locomotives of railways worldwide have been using sand since 1838 to improve the wheel–rail adhesion during traction and braking operations. In more recent years, sanders have also been fitted to electrical and diesel multiple units in some railways to fight (often in combination with traction control or wheel slide protection systems) the low-adhesion conditions, especially encountered in autumn due to leaf contamination. In spite of the worldwide broad use of sand, different standards on sanding practice appear to be used by different railways, while there is a lack of fundamental understanding on the influence of sanding parameters, such as particle size distribution, feed rate, and number of sanding axles (among others), on the adhesion recovery, wear, and train detection. In order to gain a better understanding of these interrelationships, the authors have carried out laboratory investigations in recent years. As a continuation of that work, the influence of the sand particle size on the adhesion recovery in leaf-contaminated contacts is investigated in this article by means of traction tests of an electrical locomotive in a stabling yard. Three differently sized silica sands are used in the testing. In addition to the particle size investigations, the standard sand currently used in the Dutch railways is also tested to quantify its effectiveness against leaf contamination. Besides the immediate adhesion improvement upon sanding, the remaining friction level left for subsequent tractive wheel passages is also investigated for all sands tested. Furthermore, baseline tests (i.e. without application of sand) are also performed to obtain some quantitative insight into the impact of leaf contamination on the wheel–rail adhesion in the field.

Development of a New Wheel Slide Protection System Using a New Detection Algorithm

Reducing the braking distance is very important to improve the safety of a railway system. However, increasing braking force to achieve this often causes wheel slide under wet conditions because the adhesion force between the wheel tread and rail governs braking performance. This has led to the development of a number of methods including "Anti-skid (Anti-lock) Brake System (ABS)," "Wheel Slide Protection system (WSP)," etc,. This paper proposes an advanced WSP using a new algorithm to detect wheel slip to achieve a higher level of performance than current systems. We also show the effectiveness of the proposed method by means of line tests.

A scaled roller test rig for high-speed vehicles

Scaled roller rigs are quite widespread among railway research centres, and several examples are described in the literature. Due to their low costs and ease of use compared with full-scale counterparts, these types of rigs are used for a wide range of studies concerning dynamical stability, comfort, mechatronic subsystem and wear. Furthermore, scaled roller rigs can be a powerful education tool for railway engineering students. In this paper, the design and the main features of the scaled rolled rig that will be installed in the Mechatronics and Dynamic Modeling Laboratory of the University of Florence located in Pistoia, Italy, are described. The main feature of the proposed rig will be the simulation of degraded adhesion conditions. This feature is very important for hardware-in-the loop testing of many safety relevant on-board subsystems like wheel slide protection systems, traction and stability controls, odometry and automatic train protection and control.

A railway vehicle multibody model for real-time applications

Hardware in the loop (HIL) techniques are widely used for fast prototyping of control systems, electronic and mechatronic devices. In the railway field, several mechatronic on board subsystems are often tested and calibrated following the HIL approach. The accuracy of HIL tests depends on how the simulated virtual environment approximates the physical conditions. As the computational power available on real-time hardware grows, the demand for more complex and realistic models of railway vehicles for real-time application increases. In past research activities, the authors worked on the implementation of simplified real-time models for several applications and in particular for an HIL test rig devoted to the type approval of wheel slide protection systems. The activity has then been focused on the development of a three-dimensional model of the dynamics of a railway vehicle for more complex applications. The paper summarises the features and the results of the study.

HIL simulation of WSP systems on MI-6 test rig

In this article, a multi-purpose platform for Hardware In the Loop (HIL) testing of safety relevant railway subsystems, such as odometry boards or wheel slide protection systems, is shown. The rig, called MI-6, is a product of the cooperation of Trenitalia with researchers of Dip. Energetica Sergio Stecco (University of Florence). In this work, special attention has been paid to vehicle real-time model optimization according to customer specifications (Trenitalia) and to simulate artificially degraded adhesion between rolling surfaces where conventional adhesion models have poor performances or require unaffordable computational resources for real-time applications. In this article, a heuristic model based on energetic considerations and a wide archive of experimental test (courtesy of Trenitalia Società per Azioni) is presented. Also some simulation results and comparison with the experimental data are shown.