The Development of Measurement and Characterization Techniques of Road Profiles

The principal excitation to a vehicle's chassis system is the road profile. Simulating a vehicle traversing long roads is impractical and a method to produce short roads with given characteristics must be developed. By understanding the characteristics of the road, a reduced set of models can be created from which appropriate representations of the terrain can be synthesized. Understanding the characteristics of the terrain requires the ability to accurately measure the terrain topology. It is only by increasing the fidelity and resolution of terrain topology data that application of these data can be advanced. The first part of this work presents the development of a high fidelity 3-D laser terrain measurement system. The system is developed for both on-highway and off-road measurement. It is capable of measuring terrain in three dimensions, whereas current systems measure separate 2-D profiles in each wheel path of the vehicle. The equipment setup and signal processing techniques are discussed, as well as future improvements and applications of this enabling technology.

The second part of this work develops a method of characterizing non-stationary road profile data using ARIMA (Autoregressive Integrated Moving Average) modeling techniques. The first step is to consider the road to be a realization of an underlying stochastic process. The model identification techniques are demonstrated. Statistical techniques are developed and used to examine the distribution of the residual process and the results are demonstrated. The use of the ARIMA model parameters and residual distributions in classifying road profiles is also discussed. By classifying various road profiles according to given model parameters, any synthetic road realized from a given class of model parameters will represent all roads in that set, resulting in a timely and efficient simulation of a vehicle traversing any given type of road.