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Improved sinkage algorithms for powered and unpowered wheeled vehicles operating on sand

George L. Mason, Farshid Vahedifard, Joe D. Robinson, Isaac L. Howard, George B. McKinley, Jody D. Priddy
Journal of Terramechanics, Volume 67, October 2016, Pages 25-36, ISSN 0022-4898,
Modeling and simulation of vehicles in sand is critical for characterizing off-road mobility in arid and coastal regions. This paper presents improved algorithms for calculating sinkage (z) of wheeled vehicles operating on loose dry sand. The algorithms are developed based on 2737 tests conducted on sand with 23 different wheel configurations. The test results were collected from Database Records for Off-road Vehicle Environments (DROVE), a recently developed database of tests conducted with wheeled vehicles operating in loose dry sand. The study considers tire diameters from 36 to 124 cm with wheel loads of 0.19–36.12 kN. The proposed algorithms present a simple form of sinkage relationships, which only require the ratio of the wheel ground contact pressure and soil strength represented by cone index. The proposed models are compared against existing closed form solutions defined in the Vehicle Terrain Interface (VTI) model. Comparisons suggest that incorporating the proposed models into the VTI model can provide comparable predictive accuracy with simpler algorithms. In addition to simplicity, it is believed that the relationship between cone index (representing soil shear strength) and the contact pressure (representing the applied pressure to tire-soil interface) can better capture the physics of the problem being evaluated.  
Keywords: Vehicle off-road mobility; Sand; Traction; Sinkage; Vehicle Terrain Interface (VTI); Database Records for Off-road Vehicle Environments (DROVE)