CDS&E: Computational and Experimental Studies on Dynamic Interactions With Soft Soil

软土上的移动对许多导航和勘探作业非常重要，包括沿海、石油和淡水资源的勘探，外星地形导航，地雷和辐射探测的测绘作业，以及搜索和救援作业。一般来说，与在填充表面上的运动相比，在松软或松散的土壤上运动需要更高的能量消耗。通过该奖项的支持，将继续进行基础研究，以进一步了解机车与不同颗粒介质的相互作用。这项研究将利用不同领域的知识，包括土壤建模、数值模拟、车辆动力学和数据挖掘。一个显著的影响预计将是我们对车辆在颗粒状介质中的机动性和相关能源效率策略的理解的进步。这种跨学科的研究将为相关研究人员提供特殊的学习机会，并迎来受过计算建模和科学培训的新一代研究人员。在该团队先前在计算和实验动力学、非线性现象和流体-结构相互作用方面的努力的指导下，这项研究工作将集中于了解与软土上轮式和腿式运动相关的颗粒介质相互作用。最初的实验将通过使用光弹性颗粒来检查颗粒间力链的发展，以响应外部载荷产生的局部表面扰动。这些实验有望为基于离散元素模型的颗粒相互作用的模拟产生数据。这些模拟将利用GPU计算。将使用连续介质、地质力学-流体动力学模拟来将观测到的力链与特定的土壤类型相关联。这项研究工作将有助于回答以下基本问题：i)力链能用来预测软土相互作用中的滑动吗？Ii)是否存在使土壤滑移最小化的最佳步速？3)球体与复杂的摩擦模型相结合，能否以统计平均的方式准确地模拟沙粒与其他非球形物体的相互作用？以及iv)是否可以将Tracy-Widom分布等统计分布应用于与颗粒介质的相互作用？这些发现有望提供一种独特的手段，以一种仅通过实验无法处理的方式来研究机车相互作用的颗粒反应。预计研究结果将有助于为机器人平台开发有效的推进策略，这些平台跨越一系列不同的大小、重量、速度和能源消耗目标。

Locomotion on soft soil is important for many navigation and exploration operations, including explorations for coastal, petroleum, and fresh water resources, extraterrestrial terrain navigation, mapping operations for mine and radiation detection, and search and rescue operations. In general, motions on soft or loose soil require high energy expenditures compared to motions on packed surfaces. Through support of this award, fundamental research will be pursued to gain further understanding of locomotive interactions with different granular media. This research will draw upon knowledge from various areas, including soil modeling, numerical simulations, vehicle dynamics, and data mining. A salient impact is expected to be the advancement of our understanding of vehicle maneuverability in granular media and related strategies for energy efficiency. The cross-disciplinary research will provide exceptional learning opportunities for the researchers involved and also usher in new generation of researchers trained in computational modeling and sciences. Guided by the team's prior efforts in computational and experimental dynamics, nonlinear phenomena, and fluid-structure interactions, this research effort will be pursued with a focus on understanding granular media interactions associated with wheeled and legged locomotion on soft soils. Original experiments will be conducted by using photo-elastic granules to examine inter-granular force chain development in response to local surface disturbances generated by external loading. These experiments are expected to generate data for simulations of granular interactions based on discrete element models. These simulations will leverage GPU computing. Continuum, geomechanical-hydrodynamic simulations will be used to associate observed force chains with specific soil types. The research effort will help answer basic questions such as the following: i) Can force chains be used to predict slipping in soft-soil interactions? ii) Does an optimum gait speed exist at which soil slipping is minimized? iii) Can spheres, combined with complex friction models, accurately simulate interactions of sand grains and other non-spherically shaped bodies in a statistically averaged sense? and iv) Can one apply statistical distributions such as the Tracy-Widom distribution to interactions with granular media? The findings are expected to provide a unique means for interrogating granular reactions to locomotive interactions in a way not tractable through experimentation alone. The outcomes are expected to be useful for developing efficient propulsion strategies for robot platforms that span a range of different sizes, weights, speeds, and energy consumption targets.