Title: Off-road lateral stability analysis of an articulated steer vehicle with a rear-mounted load

Authors: N.L. Azad, J. McPhee, A. Khajepour

Addresses: Mechanical Engineering Department, University of Waterloo, Ontario N2L 3G1, Canada. ' Motion Research Group, Department of Systems Design Engineering, University of Waterloo, Ontario N2L 3G1, Canada. ' Mechanical Engineering Department, University of Waterloo, Ontario N2L 3G1, Canada

Abstract: To investigate the lateral stability of an articulated steer vehicle with a rear-mounted load, a linearised model of a forestry skidder carrying a log is devised. In this model, a torsional spring and damper are used to represent the stiffness and damping in the hydraulic cylinders at the articulation joint. The results show that when the vehicle is carrying a rear-mounted load, the oscillatory instability or snaking may occur at lower vehicle speeds. However, when the torsional spring stiffness or damping at the articulation angle is increased to an appropriate value, the snaking can be removed or delayed to higher speeds. To verify the results from the analysis of the linearised model, the motion of a virtual prototype of the vehicle is simulated in ADAMS/View. The results from the simulations and linear stability analysis are consistent.

Keywords: articulated steer vehicles; lateral stability analysis; snaking; oscillatory instability; linearised model; virtual prototype; rear-mounted loads; mobility number; off-road vehicles; forestry skidder; torsional springs; torsional dampers; stiffness; damping; hydraulic cylinders; articulation joints; simulation; modelling.

DOI: 10.1504/IJVSMT.2005.008575

International Journal of Vehicle Systems Modelling and Testing, 2005 Vol.1 No.1/2/3, pp.106 - 130

Published online: 04 Jan 2006 *

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