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• Paper reviews operation and parameters of archimedean scroll propulsion systems. • A thorough review of literature on scroll propulsion vehicles is presented. • An emerging application of screw propulsion are uncrewed ground vehicles. This paper provides a comprehensive review of the published literature on screw propulsion for off-road vehicles and amphibious transportation, from its origins in the 18th century to the present day. Additionally, this work describes the basis and elements of an archimedean scroll propulsion mechanism and discusses the most developed dynamic models available in the literature and their limitations. The paper also examines the need for a tested terramechanics dynamic model and explores potential future applications of screw propulsion technology for uncrewed ground vehicles and robotic planetary exploration. [ABSTRACT FROM AUTHOR]

• A novel tool-soil interaction model for a scoop sampler was developed and validated. • Work extends Mori model to account for soil cohesion, adhesion and surcharge effects. • Terramechanics models used to obtain interaction forces between sampler and soil. • Proposed model is compared and validated against earlier model in simulation studies. • In experiments, model predictions agree with measurements in cohesive, adhesive soil. 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. [ABSTRACT FROM AUTHOR]

Ground cover and surface vegetation information are key inputs to wildfire propagation models and are important indicators of ecosystem health. Often these variables are approximated using visual estimation by trained professionals but the results are prone to bias and error. This study analyzed the viability of using nadir or downward photos from smartphones (iPhone 7) to provide quantitative ground cover and biomass loading estimates. Good correlations were found between field measured values and pixel counts from manually segmented photos delineating a pre-defined set of 10 discrete cover types. Although promising, segmenting photos manually was labor intensive and therefore costly. We explored the viability of using a trained deep convolutional neural network (DCNN) to perform image segmentation automatically. The DCNN was able to segment nadir images with 95% accuracy when compared with manually delineated photos. To validate the flexibility and robustness of the automated image segmentation algorithm, we applied it to an independent dataset of nadir photographs captured at a different study site with similar surface vegetation characteristics to the training site with promising results. • Forest ground cover and surface vegetation were documented with smartphone photos. • The downward (nadir) photos were manually segmented into 10 discrete cover types. • Percent cover from manually classified pixels correlated well with field measurements. • A deep convolution neural network (DCNN) was trained to segment cover automatically. • The DCNN segmentation had 95% accuracy and independent validation showed promise. [ABSTRACT FROM AUTHOR]

• Counter-rotating Archimedean screws enable locomotion across challenging terrains. • Only a few terramechanics models for screws have been published and have limitations. • We present a novel testing apparatus to perform scroll terramechanics experiments. • Hardware tests show system will be useful for future terramechanics model development. Modeling the force interaction between a wheel and the ground is necessary when evaluating the effectiveness of a vehicle's mobility on challenging terrain. Soft soils with low bearing strength are a particularly difficult medium for wheeled vehicles. Helical scrolls have shown promise as an alternative to wheels which can work across a range of terrains, warranting a detailed terramechanics study to model their capabilities. Most of the existing terramechanics literature is limited to wheels and often employs an apparatus to study single wheels in a fixed geometry. This paper describes the design and implementation of a novel apparatus capable of housing a range of scroll geometries and configurations. The apparatus is comprised of a soil container, carriage to drive the scroll in two operating configurations, and a surrounding frame that enables both vertical and horizontal motions of the carriage. The carriage is outfitted with a drive system and instrumentation to measure the sinkage, stress, and drawbar pull values required for a terramechanics characterization. Initial stress-sinkage curves for three different scroll configurations align with expected results and provide a proof of concept that the proposed apparatus can successfully measure differing geometric parameters and can be used for further terramechanics characterizations. [ABSTRACT FROM AUTHOR]

• Robotic soil property measurement reduces risks & costs in challenging terrains. • A robotic vane shear test tool was developed with high resolution and accuracy. • Advantages over manual instrumentation are discussed with lab and field results. • Sources of error, calibration, and test procedures are presented. The present work describes the development of a novel robotic vane shear test tool for characterization of soil parameters with high precision and accuracy. The tool automates industrial standards for testing procedures. The proposed system is capable of performing high resolution torque measurements, which are then used to estimate the shear strength of the soil. The design of the instrument and its advantages over traditional manual instruments are discussed, after which error sources, calibration, and test procedures are described. The developed tool was successfully validated against high-end commercial equipment. The built unit was employed for characterizing mine waste in a laboratory setting and also deployed in the field on board an Unmanned Ground Vehicle for remote soil characterization. [ABSTRACT FROM AUTHOR]