Integrated Controls of Lateral Vehicle DynamicsSUMMARY A study is presented dealing with the synergism coming from the integration of such controlled systems which are designed for improving the dynamic khanour of road vehicles. A modified 114 car model is derived which allows suspension, toque and steering control to be applied to a low order vehicle model. A number of investigaiiong based either on complex vehicle models or on ground test$ show that impawt synergistic etTec4s can be c&ained from the integration of suspension, toque and steering controls. The .stmight nvlning on kegular raads may take advantage h m the cadperation of active suspension and four-wheel-steering systems. The brakmg under )I-split conditions can be improved with a pmper control of ABS and rear w h d steering. The driveability of a car entering a curve with c m surfaoe conditions could be substantially enhanced thanks to the combined exploitation of ABS and additional four wheel steering.

To derive an approximation from the steady state measurements of tyre characteristics an approach in two steps is chosen. First the measurements of the tyre forces in a preprocessed form are normalized with the maximum contact coefficients and the corresponding slip values. Then, with the measurements now forming a very narrow band, a single curve can be used t o approximate the whole tyre characteristics. The mutual influences of Lateral and longitudinal forces are taken into account with combined slip values, which cover the whole range from locked wheels to heavy spinning wheels including small camber angles. Different surface conditions are considered with three parameters and the sliding coefficient so that the change of original characteristics can be handled easily.The self aligning torque is described by three components: the lateral force times pneumatic trail, the spin-slip torque and the reaction of lateral deflection and longitudinal force. Once again for the approximation of the pneumatic trail a normalization is used leading t o a single curve for the whole characteristic. A similar method was applied to get a feasible approximation for the spin-slip torque.For the validation of the approximation comparisons of calculated and measured characteristics are presented. Whole characteristics for a tyre moving with lateral and longitudinal slip demonstrate the possible range of application.

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The dynamic behavior and ride quality of railway vehicles are influenced by track quality. Monitoring riding comfort and safety is a major task of the Austrian Federal Railway’s Infrastructure Division. The track testing and recording car EM 250 provides a proven measuring instrument for modern track maintenance. Equipped with an inertial measuring system and an optical track gauge measuring system, the track testing and recording car can measure the track alignment and rail profiles at speeds of up to 220 km/h. The measurements, taken every 25 cm, provide binary data files that can be processed offline. Track quality parameters are measured as functions of vehicle acceleration and are stored in a database from which they can be easily retrieved from any computer in the company. The Bureau for Applied Mechanics and Mathematics was commissioned by the Austrian Federal Railways to develop the SIMULAT program for analyzing rolling stock dynamics. In developing the model, special consideration was given to the exact mathematical description of all elements affecting vehicle dynamics. Using an optical measuring system, the track testing and recording car determines the rail cross section on the basis of readings at individual points. The simulation program links the curve with the track data, allowing the analysis of the impact of worn profiles on running stability. For the simulation, the line layout and the track geometry deviations excite the model of track and vehicle. In a followup phase, the vector of generalized degrees of freedom is evaluated, and the results are displayed with a visualization program. The simulation results were compared with data recorded during a test run and showed satisfactory correspondence.

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