The development of a soil trafficability model for legged vehicles on granular soils

This paper extends previous research in planetary microrover locomotion system analysis at the University of Surrey through the development of a legged microrover mobility model. This model compares various two- and three-dimensional soil cutting models to determine the most applicable model to legged locomotion in deformable soils, and is flexible to use any of these models depending on the leg shape, sinkage and other conditions. This baseline draught force model is used for determining the soil forces available for legged vehicle locomotion, as well as the soil thrust available to the vehicle footprint. Empirical investigations were performed with a robotic arm in planetary soil simulants to validate a legged mobility model through determination of the draft force of a robotic leg pushing through soil at constant and varying sinkage levels. The resulting locomotion performance model will be used to predict the ability of the legged vehicle to traverse a specific soil. An introduction to the planetary soil simulants used in this study (SSC-1 quartz-based sand and SSC-2 garnet-based sand) and the process used to determine their mechanical properties is also briefly presented to provide a baseline for this research.

► First mathematical model to predict legged vehicle mobility in compressible soils.
► Validation of model through empirical testing in 2 soil simulants.
► Application of draught force as the primary factor for legged mobility performance.
► Extrapolation of model to predict legged vehicle mobility on planetary soils.