Speed-made-good: Mobility map generation for wheeled vehicles on soft terrain

Abstract

The Nepean Wheeled Vehicle Performance Model (NWVPM) software has been in use for decades as a tool for engineers in industry and governmental agencies to predict the performance of off-road wheeled vehicles. It is based on the Bekker-Wong wheel-terrain interaction model which takes into account both the normal pressure and shear stress distributions at the wheel-terrain interface and uses the Bekker-Wong terrain parameters to characterize the terrain behavior. Using terrain and vehicle parameters as inputs, NWVPM computes various traction indicators such as drawbar pull, tractive effort, sinkage, and external motion resistance as functions of wheel slip by solving a set of equilibrium equations. This paper describes a novel method for predicting vehicle speed-made-good mobility maps and fuel consumption through an analytical approach using NWVPM. To evaluate the proposed method for predicting speed-made-good, a comparison is made with predictions obtained using Vortex, a commercial multibody dynamic simulation software that performs dynamic simulations of vehicles on soft terrain. In addition, a comparison of the capabilities of NWVPM and Vortex in predicting off-road vehicle performance over a range of terrains is presented and the results of the drawbar pull traction test from both software are compared with experimental data.