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1. Planning for Robotic Dry Stacking with Irregular Stones

   https://doi.org/10.1007/978-981-15-9460-1_23  

   Liu, Y ; Choi, J ; Napp, N ( January 2021 , Field and Service Robotics)

   Ishigami, G ; Yoshida, K (Ed.)

   The ability to build structures with autonomous robots using only found, minimally processed stones would be immensely useful, especially in remote areas. Assembly planning for dry-stacked structures, however, is difficult since both the state and action spaces are continuous, and stability is strongly affected by complex friction and contact constraints. We propose a planning algorithm for such assemblies that uses a physics simulator to find a small set of feasible poses and then evaluates them using a hierarchical filter. We carefully designed the heuristics for the filters to match our goal of building stable, free-standing walls. These plans are then executed open-loop with a robotic arm equipped with a wrist RGB-D camera. Experimental results show that the proposed planning algorithm can significantly improve the state of the art in robotic dry stacking. 

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2. Approximate Stability Analysis for Drystacked Structures

   Liu, Yifang ; Saboia, Maira ; Thangavelu, Vivek ; Napp, Nils ( May 2019 , International Conference on Robotics and Automation (ICRA2019))

   We introduce a fast approximate stability analysis into an automated dry stacking procedure. Evaluating structural stability is essential for any type of construction, but especially challenging in techniques where building elements remain distinct and do not use fasteners or adhesives. Due to the irregular shape of construction materials, autonomous agents have restricted knowledge of contact geometry, which makes existing analysis tools difficult to deploy. In this paper, a geometric safety factor called kern is used to estimate how much the contact interface can shrink and the structure still be feasible, where feasibility can be checked efficiently using linear programming. We validate the stability measure by comparing the proposed methods with a fully simulated shaking test in 2D. We also improve existing heuristics-based planning by adding the proposed measure into the assembly process. 

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3. Learning Models for Predictive Adaptation in State Lattices

   Napoli, Michael E. ; Biggie, Harel ; Howard, Thomas M. ( September 2018 , 11th International Conference on Field and Service Robotics)

   Approaches to autonomous navigation for unmanned ground vehicles rely on motion planning algorithms that optimize maneuvers under kinematic and environmental constraints. Algorithms that combine heuristic search with local optimization are well suited to domains where solution optimality is favored over speed and memory resources are limited as they often improve the optimality of solutions without increasing the sampling density. To address the runtime performance limitations of such algorithms, this paper introduces Predictively Adapted State Lattices, an extension of recombinant motion planning search space construction that adapts the representation by selecting regions to optimize using a learned model trained to predict the expected improvement. The model aids in prioritizing computations that optimize regions where significant improvement is anticipated. We evaluate the performance of the proposed method through statistical and qualitative comparisons to alternative State Lattice approaches for a simulated mobile robot with nonholonomic constraints. Results demonstrate an advance in the ability of recombinant motion planning search spaces to improve relative optimality at reduced runtime in varyingly complex environments. 

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4. Lunar Infrastructure via Microscale Regolith Assembly

   https://doi.org/10.2514/6.2021-0148  

   Eckman, Elise ; Peck, Mason A. ; Napp, Nils ( January 2021 , AIAA 2021-0148 Session: Flight Systems and In-Space Infrastructure)

   null (Ed.)

   Multiscale Granular Stacking (MSGS) is a technology for assembling planetary-surface infrastructure from unprocessed regolith. The unprocessed grains serve directly as additive manufacturing feedstock in a process that exploits their natural variation in size and shape. With precise, single-grain scanning, computation, and packing, MSGS minimizes and potentially eliminates the need for adhesives, fluids, and other binders, saving the associated mass and energy. Preliminary calculations suggest that MSGS requires less mass transport and energy for construction than traditional terrestrial building methods, drastically reducing the reliance on earth resources for sustaining a deep-space human presence and long-term exploration goals. Constructing a desired structure may require stacking millions of grains which demands extensive computation. Packing solutions with many objects exist in the literature, e.g. some versions of the knapsack problem. However, micro- to macro-scale particle dry stacking itself has never been investigated, let alone in the context of space additive manufacturing. Modeling these fabrication process dynamics as a discrete-step linear system allows for tuning of parameters such as build speed, surface finish, and contour smoothing while providing the opportunity to leverage controls theory for determining system convergence, steady-state error, and overshoot of desired build height. This paper details attempts to bring multivariable control theory to bear on additive manufacturing by using feedback on overall build geometry, a technique proven to yield more accurate results than using feedback at the process level in traditional additive manufacturing. 

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5. Assessing the availability of green infrastructure to residents of an Arctic city (on the example of Nadym) [Оценка обеспеченности зеленой инфраструктурой жителей арк­тического города (на примере Надыма)]

   https://doi.org/10.25283/2223-4594-2022-4-475-490  

   Sizov, O.S. ; Fedorov, R.Y. ; Pechkina, Y.A. ; Michugin, M.S. ; Kuklina, V.V. ; Soromotin, A.V. ; Fedash, A.V. ( December 2022 , Arctic: Ecology and Economy)

   Based on remote sensing data, the authors consider the features of the formation and use of green spaces in the city of Nadym (Yamalo-Nenets Autonomous Area). They give a detailed assessment of the availability of green infrastructure for the inhabitants of Nadym based on a comparison of the spatial distribution of vegetation and the urban population. During the construction of the city, there was a dramatic reduction in the area of vegetation cover, which reached its maximum during active construction in the 1980s. After the completion of the main construction stage and until now, there has been a steady increase in the share of vegetation, which is explained by active landscaping activities against the backdrop of climate softening. The authors have find out that while maintaining the high availability of open green spaces within the city, the main lack of vegetation is observed within the residential development of microdistricts. The methodology for the integrated use of medium and ultra-high resolution space images, UAV surveys, detailed mapping of residential buildings and field geobotanical descriptions tested during the study can be used in a detailed analysis of the state of the green infrastructure of other cities in the north of Western Siberia. In general, the assessment of the green infrastructure availability in the Arctic cities is of great importance for urban planning, allowing to fully take into account the regional environmental needs of local residents, in the context of the heterogeneity of their distribution. 

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