A framework for the characterization of the transient handling responses of non-linear vehicles

Abstract

The paper attempts to provide an integrated framework for the objective assessment of the transient handling responses of non-linear vehicles. The ultimate aim of the proposed framework is the characterization of such responses as neutral or under/over-steering. A new methodology is employed, which has previously been applied for the classification of the transient response of linear vehicles. The success of the proposed method is judged based on its robustness, the consistency of the results, and their practical implications. Furthermore, the results are compared with the findings of traditional approaches for the characterization of the steady-state and transient handling behaviour. The corresponding discussion reveals the agreement between the approaches, but also highlights the slightly different definition of the neutrally steering vehicle, as perceived by the proposed method.

A study on the influences of tyre lags and suspension damping on the instantaneous response of a vehicle

“…The methodology presented in [6], [7], has been successfully applied for the investigation of transient handling responses, including the effects of tyre force lags and suspension damping. The use of simple 2-DOF models has highlighted the main trends with respect to tyre force lags.…”

“…The transient handling assessment methodology is presented in detail in references [6] and [7]. The fundamental concept is introduced in [6] where a linear bicycle model is subjected to step-steer excitations.…”

“…In [6] the extension of the use of steady-state terminology (under-, over-and neutral-steer) into transient operating conditions is attempted. In [7] the method is applied to a bicycle model with non-linear tyre forces and it is demonstrated that, if the input is severe enough, the vehicle's character might change during the course of a transient manoeuvre, following precisely the changes predicted by the steady-state handling diagram [2], [5]. A brief overview of the handling assessment method is provided in the present section in order to facilitate understanding of the results presented in subsequent sections.…”

“…The methodology for transient handling assessment discussed in section 2 has been applied for the analysis of trivial manoeuvres performed with simple vehicle models [6], [7]. In an attempt to evaluate the performance of the method under more realistic conditions, the parameters of the full vehicle model were matched those of a Jaguar XJ350 test vehicle.…”

“…In any case, the characterisation of a vehicle as under-, over-, or neutral-steering has only been defined for steady-state operating conditions. Recently, a framework has been developed [6], [7] which extends the applicability of the aforementioned characterisations/terms in transient operating conditions. The methodology is based on the definition of an assumedly 'neutral' behaviour under transient conditions and the subsequent comparison of the instantaneous behaviour of a vehicle with this 'neutral' behaviour.…”