Scott. Simson

Co-simulation of a mechatronic system using Gensys and Simulink

The design of mechatronic systems for rail vehicles requires the implementation of modern software tools. Nowadays, it is common to use co-simulation for the creation of mechatronic models. This approach is usually based on the combination of two types of software – multi-body simulation packages for mechanical models and tools for simulation of electric, control systems, etc. The existing commercial codes (SIMPACK, VI-RAIL, VAMPIRE, UM) provide different approaches for co-simulation; however, they have a lot in common. The one thing that makes them very similar is the use of Simulink for co-simulation. In this paper, we propose a description of the client interface in Simulink for co-simulation with Gensys. The evolution of the proposed approach has been performed by means of a simulation of a simplified traction control system for a hauling locomotive running on straight track conditions.

Simulation of Curving at Low Speed Under High Traction for Passive Steering Hauling Locomotives

The traction control in modern electric and diesel electric locomotives has allowed rail operators to utilise high traction adhesion levels without undue risk of damage from uncontrolled wheel spin. At the same time, some locomotive manufacturers have developed passive steering locomotive bogies to reduce wheel rail wear and further improve locomotive adhesion performance on curves. High locomotive traction loads in curving are known to cause the loss of steering performance in passive steering bogies. At present there are few publications on the curving performance of locomotive steering with linkage bogies. The most extreme traction curving cases of low speed and high adhesion for hauling locomotives have not been fully investigated, with effects of coupler forces and cant excess being generally ignored. This paper presents a simulation study for three axle bogie locomotives in pusher and pulling train positions on tight curves. The simulation study uses moderate and high traction adhesion levels of 16.6% and 37% for various rail friction conditions. Curving performance is assessed, showing forced steering bogies to have considerable advantages over self steering bogies. Likewise it is shown that self steering bogies are significantly better than yaw relaxation bogies at improving steering under traction. As the required traction adhesion approaches the rail friction coefficient, steering performance of all bogies degrades and yaw of the bogie frame relative to the track increases. Operation with excess cant and tensile coupler forces are both found to be detrimental to the wear performance of all locomotive bogies, increasing the bogie frame yaw angles. Bogie frame pitching is also found to have significant effect on steering, causing increased performance differences between bogie designs.

Development of a real-time bogie test rig model based on railway specialised multibody software

The design of mechatronic systems of rail vehicles requires performing verification and validation in the real-time mode. One useful validation instrument is the application of software-in-the-loop, hardware-in-the-loop or processor-in-the-loop simulation approaches. All of these approaches require development of a real-time model of the physical system. In this paper, the investigation of the usage of the model of the locomotives bogie test rig created in Gensys multibody software has been performed and the calculation time for each time step has been analysed. The verification of the possibility of the usage of such an approach for real-time simulation has been made by means of a simple data transferring process between Gensys and Simulink through the TCP/IP interface. The limitations and further development issues for the proposed approach have been discussed in this paper.

Investigation of locomotive multibody modelling issues and results assessment based on the locomotive model acceptance procedure

The acceptable dynamic behaviour of railway locomotives is governed by different standards in different parts of the world. Some standards allow the use of multibody simulation tools (such as VAMPIRE, NUCARS, GENSYS and SIMPACK) in place of physical testing, but generally not for all locomotive tests within each standard. Virtual multibody locomotive models can allow simple analyses, such as for slightly modified and relocated locomotives, to be completed in less time, and lower cost and effort in comparison with physical type testing. Unfortunately, the detailed locomotive model acceptance procedures required to achieve this for locomotive designs do not presently exist. This paper discusses the methodology behind a proposed locomotive model acceptance procedure that is currently intended for Australian freight locomotives, although it can be modified to suit other countries and locomotive types. A review of relevant international standards was first undertaken to determine which tests to include and to draw from international best practice. A few case studies are then given to show how the proposed methodology can be implemented on a heavy haul locomotive model.

Simulation of Traction and Curving for Passive Steering Hauling Locomotives

Abstract In a heavy haul train operations the ruling grades that set the tractive power requirements for train consists are often associated with tight curvatures. Past studies of passive or active bogie steering developments have been mostly directed towards high-speed rail applications or light rail and commuter rail applications and hence studies have focused on two axle bogies. Linked passive steering three axle locomotive bogies such as produced by General Motors Electric Motor Division for the SD70 class locomotive are in widespread use however, there are few publications on traction and curving, and few papers on linked passive steering bogies. This paper presents a simulation study three axle bogie locomotives on various curve radii with traction and variable rail friction conditions. Curving performance is assessed showing body linked radial bogies to have considerable advantages over axle linked bogies that are significantly better than yaw relaxation bogies at improving steering under traction. As traction adhesion approaches the rail friction coefficient steering performance of all bogies without forced steering deteriorates to the same levels as a rigid bogie.

Nonlinear three-dimensional wagon–track model for the investigation of rail corrugation initiation on curved track

A nonlinear wagon–track model on curved track has been developed to characterize rail corrugation formation due to self-excitation of the wheel–rail stick–slip process. In this model, wagon movements were described using up to 78 degrees of freedom (DOFs) to model a three-piece freight bogie. Innovatively, the wheelset movements are described using nine DOFs, including torsional and bending modes about the longitudinal and vertical directions. The track modelling is considered as a one-layer structure (two rail beams on discrete spring and damper elements). The wheel sliding after creepage saturation is considered in the wheel–rail interface modelling. Simulation of a case study shows that the frequencies of the wheel stick–slip process are composed of the basic frequency, which might come from the combined effect of sleeper-passing frequency and one-third of the combined torsional and bending frequency of the wheelset, and the double and triple basic frequencies, which form the wavelengths of rail corrugation at different situations.

Idealized steering for hauling locomotives

Abstract Most of the passive and active steering developments of traction bogies have been directed towards high speed rail or light rail and commuter rail applications. Previous studies ignored coupler forces and often assumed the wheel rail profiles have ample conicity for the curving task. There is little work directed towards high adhesion rates which is a critical area for freight locomotive performance. In heavy haul train operations ruling grades are often associated with tight curvatures, and steering tasks of hauling locomotives are affected by lateral components of longitudinal train forces. Haul locomotives also have a significant yaw moment from coupler forces making uneven longitudinal creeps useful in balancing these yaw forces. The use of larger diameter wheels on locomotives reduces effective steering conicity such that contact profiles may become insufficient to negotiate tight curves. The large diameter wheels make longitudinal creepage or slip inevitable and Goodall et al. [1] definition of perfect steering unattainable. A new criteria for ideal steering in these conditions is proposed. For hauling locomotives, ideal steering is defined as when the lateral rail creep and contact loads of each axle in one bogie are equal and longitudinal creeps are positive to the applied traction. This definition is applicable to all curving tasks that a hauling locomotive encounters while still applying low wheel rail creep forces. In most of the cases ideal steering can be achieved with zero lateral creep forces. The paper describes equations for quasi-static curving forces including traction and in-train forces. An analysis of curving forces for locomotives with three axle bogies is made with the equations for various curvatures and with haulage locomotives in different train configurations including pusher configuration.

Parametric simulation study of traction curving of three axle steering bogie designs

The development of self-steering bogies in locomotives has occurred without extensive study of traction curving bogie dynamics. It is reported that these bogies are unable to steer at high tractive effort levels with the performance essentially the same as rigid bogies. This is due to the required adhesion level approaching wheel rail friction limits and causing creep saturation. Reassessment of the curve steering task in a hauling locomotive has identified that existing concepts of perfect steering [R.M. Goodall and T.X. Mei, Chapter 11: Active suspensions, in Handbook of Railway Vehicle Dynamics, S. Iwnicki, ed., Taylor & Francis Group, Boca Raton, FL, USA, 2006], [R.M. Goodall, S. Bruni, and T.X. Mei, Concepts and prospects for actively-controlled railway running gear, Vehicle Syst. Dynam. 44, supplement 1 (2006), pp. 60–70] are not appropriate for high traction loads in hauling locomotives. An extensive parametric simulation study has been conducted on steering bogie designs for hauling locomotives. Testing of passive steering bogie designs have shown superior performance from forced steering bogies where steering is only partially dependant on wheel rail creep forces. New active steering bogie designs have been proposed [S. Simson, Railway bogie, Australian Provisional Patent Application No. 2007900891, 2007] where steering control is independent of wheel rail creep forces. The new designs combine force steering of wheelsets with secondary yaw activation. The parametric study shows that new active steering bogie designs give superior steering performance under traction.

Simulation of active steering control for curving under traction in hauling locomotives

Active steering control in the form of secondary yaw control (SYC) and actuated wheelset yaw (AWY) have been in prototype development. This paper presents a new active steering bogie design, actuated yaw force steering (AY-FS), that is able to steer under high traction loads in tight curves. The AY-FS bogie design is compared with the AWY design. The steering performance AWY under high traction loads has not been previously reported. This paper examines five control methods, three for AWY and two for AY-FS bogies and assesses the traction curving and stability control performance of the alternative designs and control methods compared with each other and to passive steering bogie designs. The curving performance results showed considerable advantage in the proposed AY-FS bogies over the AWY. It was shown that control must be applied to both the yaw angle and the steering angle of the bogie to achieve the best traction steering performance which was not possible with the AWY bogies. The proposed new bogie designs of AY-FS overall give better traction curving and stability performance than the AWY designs.

Simulation of traction curving for active yaw — force steered bogies in locomotives

Abstract Steering bogies and actively steered bogies are subjected to increasing interest. Self-steering bogies have been used in large numbers of hauling locomotives primarily in the USA to reduce flange wear and improve adhesion. However, the steering performance of self-steering bogies is reported to deteriorate under traction. This article compares several bogie types and proposes a new design of steering bogie featuring forced steering combined with control of the bogie yaw movement or actuated yaw forced steered bogie (AY-FS). The bogie stability of a force steered bogie is improved by yaw actuation using a negative derivative control of the bogie yaw misalignment. An additional benefit of the bogie design is that actuators and control sensors for the AY-FS bogie can be mounted on the vehicle body rather than on the bogie frame. The article presents simulation results for a yaw actuated force steered bogie under traction curving conditions. The AY-FS bogie is compared with rigid and force steered bogies and is shown to give superior performance at high traction adhesion levels during curving. The curving performance improvements achieved depend on the curvature, lateral forces on the vehicle, the traction load, and the rail friction. The greatest curving performance advantages occur in tighter curvatures with high traction loads and low rail friction and with high lateral forces to the inside rail such as would result from coupler loads on pulling locomotives.