SAE TECHNICAL PAPER SERIES 930765 Dynamics of Four-Wheel-Steer Off-Highway Vehicles L. Daniel Metz University of Illinois at Urbana-Champaign Reprinted from: Vehicle Dynamics and Simulation (SP-950) International Congress and Exposition Detroit, Michigan March 1-5, 1993 400 Commonwealth Drive, Warrendale, PA 15096-0001 U.S.A. Tel: (412)776-4841 Fax:(412)776-5760 Downloaded from SAE International by University of New South Wales, Wednesday, September 19, 2018The appearance of the ISSN code at the bottom of this page indicates SAE's consent that copies of the paper may be made for personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay a $5.00 per article copy fee through the Copyright Clearance Center, Inc. Operations Center, 27 Congress St., Salem, MA 01970 for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to other kinds of copying such as copying for general distribution, for advertising or promotional purposes, for creating new collective works, or for resale. SAE routinely stocks printed papers for a period of three years following date of publication. Direct your orders to SAE Customer Sales and Satisfaction Depart­ ment. Quantity reprint rates can be obtained from the Customer Sales and Satisfaction Department. To request permission to reprint a technical paper or permission to use copyrighted SAE publications in other works, contact the SAE Publications Group. All SAE papers, standards, and selected books are abstracted and indexed In the SAE Global Mobility Database. No part of this publication may by reproduced in any form, in an electronic retrieval system or otherwise, without the prior written permission of the publisher. ISSN 0148-7191 Copyright 1993 Society of Automotive Engineers, Inc. Positions and opinions advanced in this paper are those of the author(s) and not necessarily those of SAE. The author is solely responsible for the content of the paper. A process is available by which discussions will be printed with the paper if it is published in SAE transactions. For permission to publish this paper in full or in part, contact the SAE Publications Group. Persons wishing to submit papers to be considered for presentation or publication through SAE should send the manuscript or a 300 word abstract of a proposed manuscript to: Secretary, Engineering Activity Board, SAE. Printed in USA Downloaded from SAE International by University of New South Wales, Wednesday, September 19, 2018930765 Dynamics of Four-Wheel-Steer Off-Highway Vehicles L. Daniel Metz University of Illinois at Urbana-Champaign ABSTRACT: Off road vehicle dynamics present fundamental differences to the engineer than those of highway vehicles. In this work, we examine off-road dynamics for a class of industrial vehicles: front-end loaders. After a review of terramechanics and off-road tire behavior, equations of motion for a front-end loader are developed. Kinematic steering relationships, steady-state performance and understeer and oversteer characteristics are also derived. Off-road front-end loader characteristics and performance in terms of vehicle handling, overturn behavior and obstacle avoidance are presented, and some design characteristics and parameter values for a typical vehicle are given to aid the designer in analysis and synthesis. TIRE MODELS INTRODUCTION - On-highway, lateral forces generated by steered tires are dominated by tire construction (stiffness and rubber properties) due to shear mechanisms of adhesion and tire-ground sliding. Off-highway, however, soil deformation and tire/terrain interaction dominate. Therefore, factors such as soil type, soil conditions, and tire tread become dominant factors. For typical conditions, tire cornering stiffness and lateral load capability off-highway may be half that of on-highway properties. Du