Validation of Handling Criteria

摘要

In order to determine the performance of different configurations and characteristics of a semi-active suspension for an off-road vehicle, appropriate handling criteria have to be defined in conjunction with ride comfort criteria. Both handling and ride comfort play an important role in the performance of a vehicle and need to be measured to judge vehicle performance. In the absence of an active suspension, the suspension characteristics usually result in a compromise between ride comfort and handling. To improve this situation, which is of special importance for vehicles such as those used by the military, which have to cope with both highway and off-road terrain, a semiactive suspension has been designed. The suspension unit, consisting of a two-stage, semiactive, hydro-pneumatic spring combined with a two stage semi-active damper, enables either good ride comfort for a compliant suspension or good handling when changed to a hard setting. The question that arises is what measures could be applied to determine when a switchover between the two settings should occur? Ride comfort has been well defined in terms of the frequency weighted mean square value of the vertical acceleration and degrees of comfort have been specified accordingly. For handling, several criteria have been put forward, which are to a more or lesser extent dependent on driver input. The paper considers the metrics that have been used for measuring handling and pays special attention to roll angle as a valid criterion. The results of tests performed on three different vehicles with four different drivers on both a dynamic handling and a ride and handling track are presented. Comparison is also made to previous results obtained from simulations and tests performed on a Land Rover for a double lane change. Special attention is paid to limiting handling criteria that can be of value in optimisation applications. The results indicate that roll angle, lateral acceleration and yaw rate are interrelated for the tracks investigated and also for severe handling manoeuvres as in the double lane change.