Articulated vehicles represent a special class of systems presenting a very complicate dynamics when a significant number of degrees of freedom is taken into account. In this case rigid body modes and flexible modes are considered together to represent the vehicle. The assumed modes technique is used to include the flexible modes in the model. Flexible modes (truck chassis and trailer chassis) are obtained from finite element calculation. The equations of motion are determined using Lagrange's technique. Symbolic computation is used to overcome difficulties due to model size. Suspension and tyre nonlinearities are considered. Simple driver action are also included in the model in order to observe the vehicle response to simulated maneuvers. Field tests are conducted to validate the model. Optimization techniques are used in order to improve suspension design and for this purpose the objective function is based on the vehicle time response.
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