Soil Kinematics Under Rigid Wheels

Experimental analysis of running gear-soil interaction traditionally focuses on the measurement of forces and torques developed by the running gear. This type of measurement provides useful information about running gear performance but it does not allow for explicit investigation of soil failure behavior. This paper describes a methodology based on particle image velocimetry for analyzing soil motion from a sequence of images. A procedure for systematically identifying experimental and processing settings is presented. Soil motion is analyzed for a rigid wheel traveling on a Mars regolith simulant while operating against a glass wall, thereby imposing plain strain boundary conditions. An off-the-shelf high speed camera is used to collect images of the soil flow. Experimental results show that it is possible to accurately compute soil deformation characteristics without the need of markers. Measured soil velocity fields are used to calculate strain fields.