NeBula: Team CoSTAR's robotic autonomy solution that won phase II of DARPA Subterranean Challenge

This paper presents and discusses algorithms, hardware, and software architecture developed by the TEAM CoSTAR (Collaborative SubTerranean Autonomous Robots), competing in the DARPA Subterranean Challenge. Specifically, it presents the techniques utilized within the Tunnel (2019) and Urban (2020) competitions, where CoSTAR achieved second and first place, respectively. We also discuss CoSTAR¿s demonstrations in Martian-analog surface and subsurface (lava tubes) exploration. The paper introduces our autonomy solution, referred to as NeBula (Networked Belief-aware Perceptual Autonomy). NeBula is an uncertainty-aware framework that aims at enabling resilient and modular autonomy solutions by performing reasoning and decision making in the belief space (space of probability distributions over the robot and world states). We discuss various components of the NeBula framework, including (i) geometric and semantic environment mapping, (ii) a multi-modal positioning system, (iii) traversability analysis and local planning, (iv) global motion planning and exploration behavior, (v) risk-aware mission planning, (vi) networking and decentralized reasoning, and (vii) learning-enabled adaptation. We discuss the performance of NeBula on several robot types (e.g., wheeled, legged, flying), in various environments. We discuss the specific results and lessons learned from fielding this solution in the challenging courses of the DARPA Subterranean Challenge competition.The work is partially supported by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (80NM0018D0004), and Defense Advanced Research Projects Agency (DARPA)

How to evaluate the wearability of electronic air filtration masks

Electronic masks are wearable devices that can replace common disposable masks. Understanding user discomfort is important for proper electronic mask evaluation and design, but the method has not been standardized yet. This study presents evaluation methods that can qualitatively and quantitatively assess user discomfort caused by wearing an electronic mask. User interviews, surveys, and laboratory experiments were conducted. The pulling force of the ear bands and the contact pressure distribution of the face were selected as quantitative evaluation variables. The task was determined in consideration of various mask use environments through user observation. The final evaluation method was applied to the comparative evaluation of the two masks. It is the first attempt to evaluate the usability of the electronic mask, and this evaluation method could improve user convenience by using it for product development and improvement

Wireless LAN with Medical-Grade QoS for E-Healthcare

In this paper, we study the problem of how to design a medical-grade wireless local area network (WLAN) for healthcare facilities. First, unlike the IEEE 802.11e MAC, which categorizes traffic primarily by their delay constraints, we prioritize medical applications according to their medical urgency. Second, we propose a mechanism that can guarantee absolute priority to each traffic category, which is critical for medical-grade quality of service (QoS), while the conventional 802.11e MAC only provides relative priority to each traffic category. Based on absolute priority, we focus on the performance of real-time patient monitoring applications, and derive the optimal contention window size that can significantly improve the throughput performance. Finally, for proper performance evaluation from a medical viewpoint, we introduce the weighted diagnostic distortion (WDD) as a medical QoS metric to effectively measure the medical diagnosability by extracting the main diagnostic features of medical signal. Our simulation result shows that the proposed mechanism, together with medical categorization using absolute priority, can significantly improve the medical-grade QoS performance over the conventional IEEE 802.11e MAC. © 2011 KICS.1

RMP-driven, ELM-crash-suppression on KSTAR for ITER

KSTAR has made significant progress in resonant magnetic perturbation (RMP)-driven, edge-localized-mode (ELM)-crash-suppression in support of ITER. Utilizing the unique capability to realize ITER-like 3-row RMP configurations, a set of intentionally misaligned configurations (IMC) have been confirmed to be not only compatible with ELM-crash-suppression, but also effective in broadening the divertor heat fluxes with minimal electromagnetic loads [1]. In contrast, since no or little broadening was found in 2-row, IMC-driven ELM-crash-suppression, the origin of the divertor heat flux broadening is being investigated. Although ideal MHD-based field line tracing was not accompanied by any broadening feature, the inclusion of plasma rotation appears quite promising. The presence of the 3rd row in IMC might have led to the additional deformation on magnetic topology that would have been helically structured by dominantly resonant components from 2 rows. Based on newly established ITER similar shape (ISS) plasmas, an initial attempt of n=1 RMP on q95\textasciitilde 3.2 was frequently challenged by mode-locking without ELM-suppression yet. The application of n=2 RMP is considered more favorable not only for ELM-crash-suppression but also for ITER-like detached plasmas. [1] Y. In et al, IAEA-FEC (2018

Study of Erosion of Carbon and Tungsten Divertor in KSTAR using ERO code

Study of Erosion of Carbon and Tungsten Divertor in KSTAR using ERO codeHeesung Parka,1, Ookjoo Rab, Kyu Been Kwonb, Suk-Ho Hongc, Hyungho Leec,Kyungmin Kimc, Kyungmin Kimc, Soohyun Son c, J. Romanovd, A. Eksaevad, A. Kirschnerd, Hae June Lee a, Min Sup Hurb,†National Fusion Research Institute, 169-148 Gwahak-ro, Yuseong-gu, Daejeon 34133, Koreaa Department of Electrical Computer Engineering, Pusan National University, 2 Busandaehak-ro 63beon-gil, Geumjeong-gu, Busan 46241, Koreab Department of Physics, UNIST, 50 UNIST-gil, Eonyang-eup, Ulju-gun, Ulsan 44919, Koreac National Fusion Research Institute, 169-148 Gwahak-ro, Yuseong-gu, Daejeon 34133, Koread Forschungszentrum Julich GmbH, Institut fur Energie- und Klimaforschung – Plasmaphysik, Partner of the Trilateral Euregio Cluster (TEC), Julich 52425, Germany [email protected]†Corresponding to [email protected] caused by sputtering of divertor targets and walls differ depending on the surface components: Low Z materials have benefits of radiation control and low core penetration, but, they have very high erosion rate. On the other hand, high Z materials have low erosion rate, while they show high core contamination [1]. KSTAR is a full carbon machine, in which 3400 blocks of graphite tiles were installed. Although carbon transport and migration were intensively studied in the past, the carbon transport in KSTAR was never studied systematically. Furthermore, KSTAR is on the way towards full tungsten wall: The erosion of new tungsten divertor and the transport of eroded tungsten atoms has to be studied. The 3D ERO code is a tool that can simulate impurity transport and wall interaction using SOLPS data as background plasma conditions in magnetically confined fusion relevant devices [2]. In this study, the erosion has been simulated for the surfaces of PFCs in KSTAR, made of carbon and tungsten using the ERO code with an EFIT equilibrium data from a shot #21376. We demonstrate changes in the characteristics of the erosion rates and concentrated erosion positions on the surface when the surface material switches from the carbon to the tungsten in the KSTAR. We discuss the limitations of each material for the long-pulse operation.[1] S.Brezinsek et al., Nucl. Fusion 54 (2014) 103001

Development of Integrated Transport Analysis Suite for LHD Plasmas Towards Transport Model Validation and Increased Predictability

In this study, the integrated transport analysis suite, TASK3D-a, was developed to enhance the physics understanding and accurate discussion of the Large Helical Device (LHD) experiment toward facilitating transport model validation. Steady-state and dynamic (transient) transport analyses of NBI (neutral-beam-injection)-heated LHD plasmas have been greatly facilitated by this suite. This will increase the predictability of the transport properties of LHD plasmas toward reactor-relevant regimes and reactor-scale plasmas