A systematic approach to reliably characterize soils based on Bevameter testing

Abstract

Although there exists a lot of information about soil parameter identification in literature, currently there is no algorithm both making use of state of the art identification methodologies and incorporating statistical analysis. In this paper a state of the art soil parameter identification method is presented including the calculation of their standard deviations and a proper weighting of the objective function. With this algorithm and a Bevameter with advanced sensor and actuator technology a test campaign is started to find a reliable soil preparation which is applicable to a large planetary rover performance testbed. Furthermore the preparation method has to be valid and stable for various types of granular soils, typically used for planetary rover testing in space robotics, since the result of pre-tests show that the soil parameters are highly depending on the preparation. Besides to the preparation soil parameters are influenced by different Bevameter test setup variables, too. Thus the effect of the penetration velocity as well as the penetration tool geometry for pressure-sinkage tests on soil parameters is investigated. For shear tests the influence of the dimension of the shear ring is also analysed as the variation of the grouser height, the number of the grouser and the increase of the rotational shear velocity. The results of the extensive test campaign are evaluated by the proposed identification algorithms.