A Method for the Characterization of Off-Road Terrain Severity 2006-01-3498

Highway and roadway surface measurement is a practice that has been ongoing for decades now. This sort of measurement is intended to ensure a safe level of road perturbances. The measurement may be conducted by a slow moving apparatus directly measuring the elevation of the road, at varying distance intervals, to obtain a road profile, with varying degrees of resolution. An alternate means is to measure the surface roughness at highway speeds using accelerometers coupled with high speed distance measurements, such as laser sensors. Vehicles out rigged with such a system are termed inertial profilers. This type of inertial measurement provides a sort of filtered roadway profile. Much research has been conducted on the analysis of highway roughness, and the associated metrics involved.

In many instances, it is desirable to maintain an off-road course such that the course will provide sufficient challenges to a vehicle during durability testing. Such situations would require an off-road terrain measurement system. A system has been developed that aims to take inertial measurements in non-paved situations. Off-road analysis provides new challenges to surface measurement. The surfaces are generally even more time-varying then paved roads, they provide greater vehicle excitations, it is difficult to maintain a constant speed when traveling over extreme terrain, and the dynamics of the suspension will be excited well beyond the points of small angle approximations and linearity assumptions. This paper will assess and compare some metrics used previously in highway applications, and adopt them to off-road conditions suitable for use in an off-road terrain severity measurement system. Further, this paper will look into new metrics to describe off road terrain for the purpose of maintaining off-road courses that are used for durability testing of all-terrain vehicles.