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A tire/terrain interaction model is presented to support the dynamic simulation of off-road ground vehicle. The model adopts a semi-empirical approach that is based on curve fits of soil data combined with soil mechanics theories to capture soil compaction, soil shear deformation, and soil passive failure that associate with off-road driving. The resulting model allows the computation of the tire forces caused by terrain deformation in longitudinal and lateral direction. This model has been compared with experimental data and shown reasonable prediction of the tire/terrain interaction.

Interactive simulation requires providing appropriate sensory cuing and stimulus/response dynamics to the driver. Sensory feedback can include visual, auditory, motion, and proprioceptive cues. Stimulus/response dynamics involve reactions of the feedback cuing to driver control inputs including steering, throttle and brakes. The stimulus/response dynamics include both simulated vehicle dynamics, and the response dynamics of the simulation hardware including computer processing delays. Typically, simulation realism will increase with sensory fidelity and stimulus/response dynamics that are equivalent to real-world conditions (i.e. without excessive time delay or phase lag). This paper discusses requirements for sensory cuing and stimulus/response dynamics in real-time, interactive driving simulation, and describes a modest fixed-base (i.e. no motion) device designed with these considerations in mind.

This paper presents a technique for assessing the influence of configuration geometry, size, and mass on the dynamics of hovering vehicles. First, the equations of motion for small perturbations from hover are discussed and certain derivatives removed or simplified from considerations of symmetry. The remaining derivatives are then related to configuration geometry, size, and mass by simple momentum theory. The accuracy of this theory is examined by comparing test results on ducted fan and free propeller configurations. The rather limited experimental data agree with the momentum theory for ducted fan configurations, provided flow separations are not important. The effects of mass and size are separated from the effects of geometry by introducing a nondimensional system of stability derivatives. It is shown how these nondimensional derivatives can be used to predict the effects of changing the mass or size of a configuration of given geometry.