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Collision warning/collision avoidance (CW/CA) systems must be designed to work seamlessly with a human driver, providing warning or control actions when the driver's response (or lack of) is deemed inappropriate. The effectiveness of CW/CA systems working with a human driver needs to be evaluated thoroughly because of legal/liability and other (e.g. traffic flow) concerns. CW/CA systems tuned only under open-loop manoeuvres were frequently found to work unsatisfactorily with human-in-the-loop. However, tuning CW/CA systems with human drivers co-existing is slow and non-repeatable. Driver models, if constructed and used properly, can capture human/control interactions and accelerate the CW/CA development process. Design and evaluation methods for CW/CA algorithms can be categorised into three approaches, scenario-based, performance-based and human-centred. The strength and weakness of these approaches were discussed in this paper and a humanised errable driver model was introduced to improve the developing process. The errable driver model used in this paper is a model that emulates human driver's functions and can generate both nominal (error-free) and devious (with error) behaviours. The car-following data used for developing and validating the model were obtained from a large-scale naturalistic driving database. Three error-inducing behaviours were introduced: human perceptual limitation, time delay and distraction. By including these error-inducing behaviours, rear-end collisions with a lead vehicle were found to occur at a probability similar to traffic accident statistics in the USA. This driver model is then used to evaluate the performance of several existing CW/CA algorithms. Finally, a new CW/CA algorithm was developed based on this errable driver model. [ABSTRACT FROM AUTHOR]

While digital map has been applied to many advanced driver assistance system applications, one critical attribute - road/lane curvature—is not available in the existing digital maps. Curvature derivation using splines is a well-known method in the computer graphics modelling community; however, it was also found that the direct application of the spline method is often not appropriate for real-time safety applications due to the resultant discontinuities in the curvature estimates and the lack of robustness against map data errors [CAMP, Enhanced digital mapping project final report, United States Department of Transportation, Washington, DC, 2004]. This paper presents a method to reconstruct road curvature attributes in real time using digital map data based on the proposed circle centre search and circle selection algorithms. Simulation and experimental results demonstrated that the proposed method can deliver curvature estimates that meet the desired accuracy. The method was also applied to the curve over-speed warning system in an on-going research project: Vehicle Infrastructure Integration—California. Some preliminary experimental results are also presented in this paper. [ABSTRACT FROM AUTHOR]

In multi-body dynamics, we model a non-conformal wheel/rail contact at one centre point since this contact is flat and Hertzian. However, the quasi-conformal contact requires more points since the contact is curved and non-Hertzian. The methodology in solving these points during dynamic simulations is the basis of this development. In this online effort, first, we present a general contact joint and the gutter search method of Pascal and Jourdan [The rigid-multi-Hertzian method as applied to conformal contacts. USA: ASME; 2007] in the context of a multi-body approach. Next, by adopting the non-iterative approach, a subset of these points with positive profile interpenetrations is selected to idealise one curved contact by a set of multi-Hertzian patches for which the Hertz normal contact solution is available. Finally, the feasibility of this multibody approach together with its implementation in two different codes is evaluated by simulating the motion of an isolated wheelset with realistic inertia. On tangent tracks, the wheelset with non-conformal pairing displays self-excited unstable oscillations while it displays a stable behaviour below a critical speed with conformal profiles. A further study reveals the net friction losses at multiple patches within the curved contact being the reason for the stable behavior. [ABSTRACT FROM AUTHOR]

In this paper, vehicle stability control and fuel economy for a 4-wheel-drive hybrid vehicle are investigated. The integrated controller is designed within three layers. The first layer determines the total yaw moment and total lateral force made by using an optimal controller method to follow the desired dynamic behaviour of a vehicle. The second layer determines optimum tyre force distribution in order to optimise tyre usage and find out how the tyres should share longitudinal and lateral forces to achieve a target vehicle response under the assumption that all four wheels can be independently steered, driven, and braked. In the third layer, the active steering, wheel slip, and electrical motor torque controllers are designed. In the front axle, internal combustion engine (ICE) is coupled to an electric motor (EM). The control strategy has to determine the power distribution between ICE and EM to minimise fuel consumption and allowing the vehicle to be charge sustaining. Finally, simulations performed in MATLAB/SIMULINK environment show that the proposed structure could enhance the vehicle stability and fuel economy in different manoeuvres. [ABSTRACT FROM AUTHOR]

Acquisition and utilization of lateral guidance information is crucialfor steering a vehicle. With practice, drivers can successfully perform thesteering function using visual perception and hand-eye coordination. However,this seemingly simple task becomes difficult when the visual information losesits clarity. Driving a snowplow during whiteout conditions is one such example.In order to improve the safety and efficiency of snow removal operations,a supplemental guidance display was proposed and successfully implementedin a California Department of Transportation (Caltrans) snowplow. The guidanceinformation was calculated based on the magnetic markers embedded in the roadway.The crucial step to this success is a transformation of the guidance displayproblem into a robust driver-in-the-loop control problem. This transformationconsiders the ‘display’ law as part of the overall driver-steering-controlalgorithm. Two key ‘assumptions’ for this design are (1) the ‘display’law should be designed in such a way that drivers can use ‘proportional’control gain alone to satisfy the performance and stability requirements ofthe steering tasks, and (2) the driver steering model can be described asa combination of gain and dynamic delay under the display law in (1). Thispaper describes the validation process for the ‘gain’ stabilizationdesign concept as well as the associated driver steering model using the initialsnowplow test data. [ABSTRACT FROM AUTHOR]

This paper describes work which has greatly improved our understanding of the processes by which rail corrugation typically develops on North American Transit systems. Several types of corrugation were identified from observations and measurements in the field. A new mechanism for corrugation formation is proposed for the most common type of corrugation observed, and a mathematical model has accordingly been developed which combines both low frequency and high frequency behaviour of the vehicle/track system. The mathematical model itself, plus results from it and from measurements are discussed here. Novel recommendations for corrugation mitigation are made. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]