Terrain surface measurements are achieved using the Vehicle Terrain Measurement System (VTMS). The VTMS is a state-of-the-art test bed for integrating technologies from different disciplines, allowing researchers to validate their theoretical and computation work with experimental data. The system is capable of scanning the complete topology of the terrain surface, in 3 dimensions, while simultaneously tracking the position, orientation, and speed of the vehicle. The VTMS provides millimeter the precision required for high-fidelity vehicle simulations for validation of vehicle and tire models, tuning of chassis components, and performance predictions.
Stochastic models are developed to characterize terrain surfaces and describe their physical characteristics. The ability to characterize terrain is critical for pavement health monitoring and durability test schedule development, for example. These mathematical models are also used to create synthetic terrain surfaces. The synthetic terrain is used whenever it is impractical to simulate very long test sections, or when simulating terrain variations that exist in the real operating conditions is important. Auto-Regressive models, Markov Chains, Hidden Markov Models, Wavelets, Kriging, and Morphological filtering are in development.
The VTPL performs empirical and analytical modeling of the vehicle and tire. Nonlinear multi-body dynamic models are developed to understand the vehicle responses to the terrain. Tires are tested to determine nonlinear characteristics, such as the enveloping properties, and models are developed based on these empirical results. For example, characteristic constraint modes are used to capture tire deformations, with the resulting modes used in a nonlinear model to predict loading.
The VTPL applies its expertise in terrain measurement and modeling, and vehicle and component modeling, to improve vehicle system performance. Improvements can be made to ride and handling metrics, durability test schedules, and subjective performance metrics. Psychometric studies quantifying the perceptions and preferences of drivers to subjective performance metrics such as ride quality have been conducted. The comprehensive suite of measurement, analysis, and modeling tools and expertise – developed by the VTPL – results in accurate predictions of a vehicle’s performance early in the development cycle enables better-informed, less-costly, and more product-focused design decisions that ultimately lead to better vehicles, tires and roads.