An improved terramechanics model for a robotic soil surface sampler

Robotic systems have been developed and deployed for sample collection and geotechnical measurements of soil characteristics. A custom scoop-type robotic soil sampler has been designed and built for sampling operations. An earlier terramechanics model for scoop samplers proposed by Mori et al. is limited to describing the interaction forces in loose sands. This paper proposes an extended model which captures the interaction of a scoop-type sampler with a wider range of soils, including cohesive and adhesive mediums, and accounts for the effects of surcharge. The proposed model was compared to the Mori model in both simulation and laboratory experiments. The forces predicted by each model agree closely for loose sand, but differ in cohesive and adhesive mediums. The proposed model was experimentally tested on dry sand and on centrifuged tailings, a cohesive and adhesive soil. In both cases, the proposed model showed close agreement between measured and predicted forces.