Evaluating Vehicle Mobility Using Bekker's Equations

Abstract

By using M.G. Bekker's equations for vehicle mobility, we have developed an analytical tool that is used for the evaluation of off-road vehicles. This allows for the departure from historical empirical models by developing universal static and transient equations that fit for all vehicles. One of our primary purposes is to develop a model for the evaluation of different mobility platforms of small robotic vehicles. These vehicles are evaluated on conditions of tractive force, tractive effort, drawbar-pull, sinkage, safe weight pressures, ground pressures, and slippage. This paper attempts to compare the mobility characteristics of wheeled vs. track vehicles for different size, weight, and terrain based off of aforementioned conditions. BDTM was originally established to give a first pass general evaluation of robotic vehicle mobility performance for different types of running gear configurations. It is a simple, linear one-degree of freedom (1-DOF) model that has been created in a spreadsheet format. The model assumes that the soil is homogenous and the loading effects are linear. The model can simulate both tracked and wheeled vehicles. These vehicles are evaluated using tractive force, tractive effort, soil sinkage, drawbar pull, and tractive coefficients (DP/W).