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A nonlinear yaw-roll model for log hauling trucks is developed in this paper. Several nonlinear effects, such as nonlinear tire cornering forces, nonlinear tire aligning moments, and the coupling between the yaw and roll motions, are considered in this model. Using this model, a computer simulation of the directional and roll responses of a logging truck with tractor and pole-trailer configurations is carried out through various maneuvers. Simulated results for the lateral accelerations are compared with those obtained from field tests. Good agreement has been achieved.

A yaw/roll simulation model is developed to assess the dynamic performance of 5, 6, 7, and 8-axle logging truck configurations in this paper. Results predicted by the yaw/roll models for a 5-axle tractor/pole trailer (with outriggers) and a 6-axle tractor/jeep/pole trailer (with outriggers) are compared with those measured in field tests for purposes of model validation. Good agreement between the simulations and measurements has been obtained. Certain performance measures for the tested tractor/pole trailer and tractor/jeep/pole trailer, such as Rearward Amplification Ratio, Load Transfer Ratio, Transient High-speed Offtracking, Understeer Coefficient, Static Rollover Threshold, and Low-speed Friction Demand, are examined by using the yaw/roll models.

A yaw roll model is proposed for investigating the effect of roll motion and suspension on the lateral dynamic behaviour of various design configurations of log hauling trucks. A detailed kinematic and dynamic analysis of this model for the truck tandem axle pole trailer combinations is carried out, and the corresponding equations of motion are established. The directional response and roll response under step and sinusoidal steer maneuvers are investigated numerically. The results obtained show that the suspension and roll motion have a significant effect on the final steady state motion in the lateral direction.