1,479 research outputs found

    The 1990 progress report and future plans

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    This document describes the progress and plans of the Artificial Intelligence Research Branch (RIA) at ARC in 1990. Activities span a range from basic scientific research to engineering development and to fielded NASA applications, particularly those applications that are enabled by basic research carried out at RIA. Work is conducted in-house and through collaborative partners in academia and industry. Our major focus is on a limited number of research themes with a dual commitment to technical excellence and proven applicability to NASA short, medium, and long-term problems. RIA acts as the Agency's lead organization for research aspects of artificial intelligence, working closely with a second research laboratory at JPL and AI applications groups at all NASA centers

    Aerospace medicine and biology: A continuing bibliography with indexes (supplement 338)

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    This bibliography lists 139 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during June 1990. Subject coverage includes: aerospace medicine and psychology, life support systems and controlled environments, safety equipment, exobiology and extraterrestrial life, and flight crew behavior and performance

    Beyond Basins of Attraction: Quantifying Robustness of Natural Dynamics

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    Properly designing a system to exhibit favorable natural dynamics can greatly simplify designing or learning the control policy. However, it is still unclear what constitutes favorable natural dynamics and how to quantify its effect. Most studies of simple walking and running models have focused on the basins of attraction of passive limit-cycles and the notion of self-stability. We instead emphasize the importance of stepping beyond basins of attraction. We show an approach based on viability theory to quantify robust sets in state-action space. These sets are valid for the family of all robust control policies, which allows us to quantify the robustness inherent to the natural dynamics before designing the control policy or specifying a control objective. We illustrate our formulation using spring-mass models, simple low dimensional models of running systems. We then show an example application by optimizing robustness of a simulated planar monoped, using a gradient-free optimization scheme. Both case studies result in a nonlinear effective stiffness providing more robustness.Comment: 15 pages. This work has been accepted to IEEE Transactions on Robotics (2019

    Coordinated multi-robot formation control

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    Tese de doutoramento. Engenharia Electrotécnica e de Computadores. Faculdade de Engenharia. Universidade do Porto. 201

    Naval Reserve support to information Operations Warfighting

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    Since the mid-1990s, the Fleet Information Warfare Center (FIWC) has led the Navy's Information Operations (IO) support to the Fleet. Within the FIWC manning structure, there are in total 36 officer and 84 enlisted Naval Reserve billets that are manned to approximately 75 percent and located in Norfolk and San Diego Naval Reserve Centers. These Naval Reserve Force personnel could provide support to FIWC far and above what they are now contributing specifically in the areas of Computer Network Operations, Psychological Operations, Military Deception and Civil Affairs. Historically personnel conducting IO were primarily reservists and civilians in uniform with regular military officers being by far the minority. The Naval Reserve Force has the personnel to provide skilled IO operators but the lack of an effective manning document and training plans is hindering their opportunity to enhance FIWC's capabilities in lull spectrum IO. This research investigates the skill requirements of personnel in IO to verify that the Naval Reserve Force has the talent base for IO support and the feasibility of their expanded use in IO.http://archive.org/details/navalreservesupp109451098

    Qos-aware fine-grained power management in networked computing systems

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    Power is a major design concern of today\u27s networked computing systems, from low-power battery-powered mobile and embedded systems to high-power enterprise servers. Embedded systems are required to be power efficiency because most embedded systems are powered by battery with limited capacity. Similar concern of power expenditure rises as well in enterprise server environments due to cooling requirement, power delivery limit, electricity costs as well as environment pollutions. The power consumption in networked computing systems includes that on circuit board and that for communication. In the context of networked real-time systems, the power dissipation on wireless communication is more significant than that on circuit board. We focus on packet scheduling for wireless real-time systems with renewable energy resources. In such a scenario, it is required to transmit data with higher level of importance periodically. We formulate this packet scheduling problem as an NP-hard reward maximization problem with time and energy constraints. An optimal solution with pseudo polynomial time complexity is presented. In addition, we propose a sub-optimal solution with polynomial time complexity. Circuit board, especially processor, power consumption is still the major source of system power consumption. We provide a general-purposed, practical and comprehensive power management middleware for networked computing systems to manage circuit board power consumption thus to affect system-level power consumption. It has the functionalities of power and performance monitoring, power management (PM) policy selection and PM control, as well as energy efficiency analysis. This middleware includes an extensible PM policy library. We implemented a prototype of this middleware on Base Band Units (BBUs) with three PM policies enclosed. These policies have been validated on different platforms, such as enterprise servers, virtual environments and BBUs. In enterprise environments, the power dissipation on circuit board dominates. Regulation on computing resources on board has a significant impact on power consumption. Dynamic Voltage and Frequency Scaling (DVFS) is an effective technique to conserve energy consumption. We investigate system-level power management in order to avoid system failures due to power capacity overload or overheating. This management needs to control the power consumption in an accurate and responsive manner, which cannot be achieve by the existing black-box feedback control. Thus we present a model-predictive feedback controller to regulate processor frequency so that power budget can be satisfied without significant loss on performance. In addition to providing power guarantee alone, performance with respect to service-level agreements (SLAs) is required to be guaranteed as well. The proliferation of virtualization technology imposes new challenges on power management due to resource sharing. It is hard to achieve optimization in both power and performance on shared infrastructures due to system dynamics. We propose vPnP, a feedback control based coordination approach providing guarantee on application-level performance and underlying physical host power consumption in virtualized environments. This system can adapt gracefully to workload change. The preliminary results show its flexibility to achieve different levels of tradeoffs between power and performance as well as its robustness over a variety of workloads. It is desirable for improve energy efficiency of systems, such as BBUs, hosting soft-real time applications. We proposed a power management strategy for controlling delay and minimizing power consumption using DVFS. We use the Robbins-Monro (RM) stochastic approximation method to estimate delay quantile. We couple a fuzzy controller with the RM algorithm to scale CPU frequency that will maintain performance within the specified QoS

    Computer detection of spatial visualization in a location-based task

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    An untapped area of productivity gains hinges on automatic detection of user cognitive characteristics. One such characteristic, spatial visualization ability, relates to users’ computer performance. In this dissertation, we describe a novel, behavior-based, spatial visualization detection technique. The technique does not depend on sensors or knowledge of the environment and can be adopted on generic computers. In a Census Bureau location-based address verification task, detection rates exceeded 80% and approached 90%

    Aerospace medicine and biology: A continuing bibliography with indexes (supplement 376)

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    This bibliography lists 265 reports, articles and other documents introduced into the NASA Scientific and Technical Information System during Jun. 1993. Subject coverage includes: aerospace medicine and physiology, life support systems and man/system technology, protective clothing, exobiology and extraterrestrial life, planetary biology, and flight crew behavior and performance

    Third International Symposium on Artificial Intelligence, Robotics, and Automation for Space 1994

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    The Third International Symposium on Artificial Intelligence, Robotics, and Automation for Space (i-SAIRAS 94), held October 18-20, 1994, in Pasadena, California, was jointly sponsored by NASA, ESA, and Japan's National Space Development Agency, and was hosted by the Jet Propulsion Laboratory (JPL) of the California Institute of Technology. i-SAIRAS 94 featured presentations covering a variety of technical and programmatic topics, ranging from underlying basic technology to specific applications of artificial intelligence and robotics to space missions. i-SAIRAS 94 featured a special workshop on planning and scheduling and provided scientists, engineers, and managers with the opportunity to exchange theoretical ideas, practical results, and program plans in such areas as space mission control, space vehicle processing, data analysis, autonomous spacecraft, space robots and rovers, satellite servicing, and intelligent instruments

    Testialustan suunnittelu hybridiajoneuvojen hardware-in-the-loop simulaatioihin

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    Recent changes to vehicle type-approval regulations have increased demand for testing methods, which better represent real-world driving conditions. Hardware-in-the-Loop (HIL) simulation is seen as an attractive alternative for pure simulations and real-world operation measurements. The goal of this work was to provide a functional testbed for engine testing, as well as for HIL simulations of Hybrid Electric Vehicles (HEVs). In addition, a state-of-the-art review of HIL was considered an important goal of the work. The theory behind HIL, and real-time systems in general, is depicted using a wide variety of examples from automotive applications relating to hybrid power sources. The knowledge gained from the literature was used to design and build a testbed in a form of an engine dynamometer. The testbed can be used to emulate rotational forces, such as load torques on a driveshaft. The testbed’s fast hardware connections enable real-time testing. The scope of the design was in mechanical design and in specification of the hardware components. Initial Internal Combustion Engine (ICE) steady-state and transient tests were done to partially validate the testbed. However, the performance was assessed to not be at an acceptable level. For example, only speed tracking passed the non-road transient cycle tracking assessment. Torque tracking and the derived power curves failed the assessment narrowly. However, the test results indicate that with proper tuning of the control software, the system performance should get better. The system response was slow at this point, but the transient behavior itself was fast. Also, in steady-state, torque and speed ripple were low. Only the preparations for HIL simulation were carried out, since the testbed was not validated to be functional enough for the much more demanding HIL tests. The preparations involved building a simulation model of a series-parallel hybrid Refuse-Collecting Vehicle (RCV), which is to be used for the verification of the designed system’s HIL capabilities. The model was independently verified to be suitable to be used for the physical tests.Viimeaikaiset muutokset ajoneuvojen tyyppihyväksyntään ovat lisänneet tarvetta testausmetodeille, jotka paremmin vastaavat oikean elämän ajo-olosuhteita. HIL-simulaatio nähdään houkuttelevana vaihtoehtona pelkälle simulaatiolle sekä ajoneuvon ajonaikaisille mittauksille. Tämän työn tavoitteena on tarjota toimiva testilaite moottoridynamometritestaukseen sekä hybridiajoneuvojen HIL-simulaatioihin. Lisäksi, HIL:in nykytilanteen kuvausta pidettiin tärkeänä työn tavoitteena. HIL:in, ja yleisemmin reaaliaikaisen testauksen, tausta ja teoria selvitettiin laaja alaisesti käyttäen esimerkkejä hybridivoimanlähteisiin liittyvistä ajoneuvoalan käyttökohteista. Kirjallisuutta hyödyntäen, testipenkki suunniteltiin ja rakennettiin. Testipenkkiä voidaan käyttää emuloimaan pyöriviä voimia, kuten vetoakseliin kohdistuvia vääntöjä. Testipenkin nopeat yhteydet mahdollistavat reaaliaikaisen testauksen. Suunnittelu oli rajattu pääasiassa mekaaniseen suunnitteluun ja komponenttien määrittelyyn. Sähkö- ja ohjelmistosuunnittelu määriteltiin yleisellä tasolla. Alustavat polttomoottorilla tehdyt vakaiden ajopisteiden ja transienttiajojen testit toteutettiin testipenkin osittaiseksi validoinniksi. Kuitenkin, laitteen suorituskyky ei yltänyt halutulle tasolle. Esimerkiksi, ainoastaan nopeusseuranta läpäisi transienttiajo testin, mutta vääntö- ja voimaseurannat epäonnistuivat täpärästi. Tulokset kuitenkin osoittavat luottamusta siitä että testipenkki saadaan aikanaan halutulle tasolle ohjelmistopuolen kontrollereja säätämällä. Tällä hetkellä systeemin vasteaika on liian pitkä, vaikka muuten dynamiikka on nopeaa. Lisäksi, vakaissa ajopisteissä vääntö- ja nopeushuojunta ovat alhaisia. Ainoastaan valmistelut HIL-simulaatiota varten saatiin toteutettua, sillä testipenkkiä ei saatu reaaliaikasta testausta vaativalle tasolle. Valmistelut sisälsivät hybridijäteauton simulaatiomallin rakentamisen, jota tullaan aikanaan käyttämään testipenkin HIL toimivuuden validointiin. Simulaatiomalli varmistettiin itsenäisenä toimivaksi, ja siten soveltuvaksi tuleviin fyysisiin testiajoihin
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