Modeling and validation of off-road vehicle ride dynamics

Abstract

Increasing concerns on human driver comfort/health and emerging demands on suspension systems for off-road vehicles call for an effective and efficient off-road vehicle ride dynamics model. This study devotes both analytical and experimental efforts in developing a comprehensive off-road vehicle ride dynamics model. A three-dimensional tire model is formulated to characterize tire-terrain interactions along all the three translational axes. The random roughness properties of the two parallel tracks of terrain profiles are further synthesized considering equivalent undeformable terrain and a coherence function between the two tracks. The terrain roughness model, derived from the field-measured responses of a conventional forestry skidder, was considered for the synthesis. The simulation results of the suspended and unsuspended vehicle models are derived in terms of acceleration PSD, and weighted and unweighted rms acceleration along the different axes at the diver seat location. Comparisons of the model responses with the measured data revealed that the proposed model can yield reasonably good predictions of the ride responses along the translational as well as rotational axes for both the conventional and suspended vehicles. The developed off-road vehicle ride dynamics model could serve as an effective and efficient tool for predicting vehicle ride vibrations, to seek designs of primary and secondary suspensions, and to evaluate the roles of various operating conditions.

Use of generated artificial road profiles in road roughness evaluation

“…Moreover, many studies on the design and analysis of vehicle suspensions are often based on the use of artificial profiles [6,7].…”

A parametric approach for evaluating the stability of agricultural tractors using implements during side-slope activities

“…Conventional tractors have been studied also in [15] through a dynamic model capable of investigating the effects of forward speed, ground slope and wheel-ground friction coefficient on the lateral stability at the presence of position disturbances. Other works, based on the same Newtonian approach, consider also a three-dimensional tire-terrain interaction model [16] or the effects of the rear track width and of an additional weight placed on the wheels, on the stability of a tractor when driving on side slopes [7]. If an agricultural implement or a trailer is connected to a tractor, the static and dynamic behaviour of the whole vehicle (tractor + implement/trailer) is substantially different from the behaviour of the same tractor alone: a tractor that is normally stable on a sloping ground could easily and unexpectedly reach critical conditions if carrying or pulling an implement.…”

Simulated stability tests of a small articulated tractor designed for extreme-sloped vineyards

“…State of the art Most of the works, however, use a Newtonian approach and some of them can consider also a three-dimensional tire-terrain interaction model (Pazooki, Rakheja, & Cao, 2012) or the effects of the rear track width and of an additional weight placed on the wheels on the stability of a tractor when driving on side slopes (Gravalos et al, 2011). Eventual trailers or agricultural implements attached to the tractor change substantially the behaviour of the whole vehicle and could easily lead it to critical conditions, thus they deserve deeper investigations.…”