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1、Full vehicle ABS braking using the SWIFT rigid ring tyre modelAbstract In recent years, at the Delft University of Technology and TNO-Automotive and in conjunction with an industrial consortium, a pragmatic tyre model has been developed going by the name SWIFT, which is geared to the analysis of tyr
2、e oscillations and its effectson vehicle behaviour. The SWIFT tyre model hasbeen designed to cover in-plane, out-of-plane and combined higher orderdynamic tyre performance. It can be regarded as an extension of the Magic Formula pragmatic tyre model, up to a range of at leastabout 70 Hz:This paper d
3、escribes the application of the SWIFT tyre model to full vehicle ABS braking. First, the model is used to derive thesingle tyre response to road undulations and brake torque step input, both being very much of relevance to ABS braking. Thisincludes a survey of the sensitivity of the dynamic tyre par
4、ameters regarding the rst, rigid belt, eigenfrequencies and the relativedamping. Next, the response of a quarter vehicle to similar input is discussed with specic emphasis on the added value of thedynamic characteristics of the SWIFT model in comparison to steady state and transient tyre models. Fin
5、ally, full vehicle ABScontrolled braking on an even road is considered for various road friction values and vehicle speed.1. IntroductionOne aspect of vehicle safety is braking as fast as possible while maintaining stability and steerability. The automotive component to achieve thisisthe ABS system,
6、 rst introduced in 1978. ABS braking initiates tyre belt oscillations and, with this in mind, a tyre model SWIFT wasdeveloped that isgeared to the analysisof tyre oscillations and its effects on vehicle behaviour. It provides for various sidewall stiffnesses, a description of the stiffness of the ty
7、re in low-velocity conditions, and a description of the slip behaviour in the contact area. The SWIFT tyre model hasbeen designed to cover both in-plane, out-of-plane and combined higher order dynamic tyre performance up to a range of at least about 70 Hz:Aspart of the applicationsof SWIFT, it can h
8、andle dynamic tyre response to brake torque variations as well as road unevennesses. SWIFT has been well validatedfor different tyres. An outline of the facilities as newly developed and applied within the SWIFT research project is given by Pauwelussen (1999). The goal of this study is to demonstrat
9、e the in-plane capabilitiesof SWIFT within a multi-body environmentand performing straight-line stops. In addition, the impact of different tyre parameterson the tyre dynamic performance aswell asthe inuence of tyre modelsonthe simulation results (i.e. the added value of SWIFT compared to steady sta
10、te and transient tyre models) are investigated. This goal is reached in different steps. First, some background information on the SWIFT tyre model and software is given. Next, in Section 3, the SWIFT software is tested for a single tyre and compared to experimental results, extended in Section 4 to
11、 a quarter vehicle (stand-alone and ADAMSs). Brake torque simulations and road disturbances (cleats) are considered and some sensitivity studies are carried out. In Section 5, full-vehicle ABS-stops are analysed with the SWIFT software linked to a full ADAMS-vehicle model and a professional ESP cont
12、rol system. Finally, the simulation results are discussed inSection 6.2. The SWIFT tyre modelAt short wavelengths and high frequencies, the dynamic tyre characteristics cannot be neglected in the study of vehicle performance. One might think here ofride comfort analysis, durability analysis, the imp
13、act of road irregularitieson the performance of active control devices (analysis of suspension with tyre exibilitiestaken into account, slip control devices, etc.). Other potential eldsof application are the wheel alignment response to dynamic tyre/road inputs, analysis of steering vibrations, tyre
14、load variations under cornering, etc.Tyre modelswith carcassexibility taken into account are required to cope with these types of practical tyreroad interaction problems. These considerations were a major motivation to start the SWIFT-project, with the objective to derive a tyre model that would be
15、able todeal with at least a signicant subset of the above problem areas. More specic, the SWIFT project was carried out, with the objective to establish pragmatic tyre modelsdescribing tyre behaviour under pure and combined slip conditions at relatively high frequency excitations p70 Hz; possibly fr
16、om road irregularitiesof relatively short wavelength 0:2m: The pragmatic SWIFT tyre model isschematically shown in Fig. 1. The basic tyre model is modelled as circular rigid ring, in-plane elastically suspended (pres-surised tyre sidewalls) to a rim in radial and circumfer-ential direction. Out-of-plane belt performance is accounted for by a lateral as well as rotational stiffnesses and damping about the longitudinal and vertical
