Collision Avoidance System using State Dependent Riccati Equation Technique: An Experimental Robustness Evaluation

The main subject of the present paper is a robustness analysis of a Collision Avoidance System for extreme changes in tyre behaviour and vehicle operation, supported by experimental results. The collision avoidance controller is based on the State Dependent Riccati Equation (SDRE) technique, which is a reconfigurable nonlinear optimal and fault tolerant control method. The SDRE based controller is robust to the nonlinearities of lateral vehicle dynamics and is also adaptive to change in the tyre-road friction potential. The robustness of the system is specifically elaborated for combined braking and steering manoeuvres and extreme oversteer conditions on different road conditions

The SWIFT tyre model : overview and applications

The Magic Formula is a very well known tyre model, which is typically applied in vehicle handling simulations. This paper summarises the developments to extend the validity range to higher frequencies (up to 60 Hz), short wavelength excitation and rolling over obstacles. The issues addressed are the dynamics of the tyre belt, contact slip model and enveloping properties. The new tyre model has been validated extensively using experimental results which show that the extended demands can be met. Finally some application examples are given

Extending the Magic Formula and SWIFT tyre models for inflation pressure changes

The Magic Formula and SWIFT tyre models are well-known semi-empirical tyre models for vehicle dynamic simulations. Up to now, the only way to account for inflation pressure changes is to identify all model parameters for each inflation pressure that has to be considered. Since this is a time consuming and consequently expensive activity, research at TNO and Eindhoven University of Technology was started to extend the Magic Formula and SWIFT tyre model so that tyre inflation pressure changes can be accounted for. This paper discusses the influence of inflation pressure changes on the quasi-static force and moment characteristics and on the enveloping properties of tyres. Die Magic Formula und das SWIFT Reifenmodell sind bekannte semi-empirische Reifenmodelle für fahrdynamische Simulationen. Bisher ist die Identifizierung aller Modelparameter für jeden Luftdruck die einzige Möglichkeit um Luftdruckveränderungen zu berücksichtigen. Da das eine zeitraubende und demzufolge teuere Aktivität ist, sind TNO und die TU Eindhoven eine Studie gestartet um die Magic Formula und das SWIFT Reifenmodell zu erweitern damit Luftdruckveränderungen berücksichtigt werden können. Dieser Beitrag geht ein auf den Einfluss von Luftdruckveränderungen auf die quasistatischen Kraftübertragungseigenschaften und auf die quasistatischen Eigenschaften des Reifens auf kurze Fahrbahnunebenheiten

Full vehicle ABS braking using the SWIFT rigid ring tyre model

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 tyre oscillations and its effects on vehicle behaviour. The SWIFT tyre model has been designed to cover in-plane, out-of-plane and combined higher order dynamic tyre performance. It can be regarded as an extension of the Magic Formula pragmatic tyre model, up to a range of at least about 70 Hz. This paper describes the application of the SWIFT tyre model to full vehicle ABS braking. First, the model is used to derive the single tyre response to road undulations and brake torque step input, both being very much of relevance to ABS braking. This includes a survey of the sensitivity of the dynamic tyre parameters regarding the first, rigid belt, eigenfrequencies and the relative damping. Next, the response of a quarter vehicle to similar input is discussed with specific emphasis on the added value of the dynamic characteristics of the SWIFT model in comparison to steady state and transient tyre models. Finally, full vehicle ABS controlled braking on an even road is considered for various road friction values and vehicle speed