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At least 865 records · Page 48

A versatile microprocessor-controlled hybrid receiver

A hybrid receiver has been designed for the Galileo Project. The receiver, located on the Galileo Orbiter, will autonomously acquire and track signals from the first atmospheric probe of Jupiter as well as demodulate, bit-synchronize, and buffer the telemetry data. The receiver has a conventional RF and LF front end but performs multiple functions digitally under firmware control. It will be a self-acquiring receiver that operates under a large frequency uncertainty; it can accommodate different modulation types, bit rates, and other parameter changes via reprogramming. A breadboard receiver and test set demonstrate a preliminary version of the sequential detection process and verify the hypothesis that a fading channel does not reduce the probability of detection.

Grant, T. L.↗

Overview of computational control research at UT Austin

An overview of current research activities at UT Austin is presented to discuss certain technical issues in the following areas: (1) Computer-Aided Nonlinear Control Design: In this project, the describing function method is employed for the nonlinear control analysis and design of a flexible spacecraft equipped with pulse modulated reaction jets. INCA program has been enhanced to allow the numerical calculation of describing functions as well as the nonlinear limit cycle analysis capability in the frequency domain; (2) Robust Linear Quadratic Gaussian (LQG) Compensator Synthesis: Robust control design techniques and software tools are developed for flexible space structures with parameter uncertainty. In particular, an interactive, robust multivariable control design capability is being developed for INCA program; and (3) LQR-Based Autonomous Control System for the Space Station: In this project, real time implementation of LQR-based autonomous control system is investigated for the space station with time-varying inertias and with significant multibody dynamic interactions.

Bong, Wie↗

Computer-Aided Remote Driving

System for remote control of robotic land vehicle requires only small radio-communication bandwidth. Twin video cameras on vehicle create stereoscopic images. Operator views cross-polarized images on two cathode-ray tubes through correspondingly polarized spectacles. By use of cursor on frozen image, remote operator designates path. Vehicle proceeds to follow path, by use of limited degree of autonomous control to cope with unexpected conditions. System concept, called "computer-aided remote driving" (CARD), potentially useful in exploration of other planets, military surveillance, firefighting, and clean-up of hazardous materials.

Wilcox, Brian H.↗

Performance of the NASA 30 cm Ion Thruster

A 30 cm diameter xenon ion thruster is under development at NASA to provide an ion propulsion option for missions of national interest, and is being proposed for use on the USAF/TRW Space Surveillance, Tracking and Autonomous Repositioning (SSTAR) platform to validate ion propulsion. The thruster incorporates innovations in design, materials, and fabrication techniques compared to those employed in conventional ion thrusters. Specific development efforts include thruster design optimizations, component life testing and validation, vibration testing, and performance characterizations. Under this test program, the ion thruster will be brought to engineering model development status. This paper discusses the performance and power throttling test data for the NASA 30 cm diameter xenon ion thruster over an input power envelope of 0.7 to 4.9 kW, and corresponding thruster lifetime expectations.

Patterson, Michael J.↗

Design Description of the X-33 Avionics Architecture

In this paper, we provide a design description of the X-33 avionics architecture. The X-33 is an autonomous Single Stage to Orbit (SSTO) launch vehicle currently being developed by Lockheed Martin for NASA as a technology demonstrator for the VentureStar Reusable Launch Vehicle (RLV). The X-33 avionics provides autonomous control of die vehicle throughout takeoff, ascent, descent, approach, landing, rollout, and vehicle safing. During flight the avionics provides communication to the range through uplinked commands and downlinked telemetry. During pre-launch and post-safing activities, the avionics provides interfaces to ground support consoles that perform vehicle flight preparations and maintenance. The X-33 Avionics is a hybrid of centralized and distributed processing elements connected by three dual redundant Mil-Std 1553 data buses. These data buses are controlled by a central processing suite located in the avionics bay and composed of triplex redundant Vehicle Mission Computers (VMCs). The VMCs integrate mission management, guidance, navigation, flight control, subsystem control and redundancy management functions. The vehicle sensors, effectors and subsystems are interfaced directly to the centralized VMCs as remote terminals or through dual redundant Data Interface Units (DIUs). The DIUs are located forward and aft of the avionics bay and provide signal conditioning, health monitoring, low level subsystem control and data interface functions. Each VMC is connected to all three redundant 1553 data buses for monitoring and provides a complete identical data set to the processing algorithms. This enables bus faults to be detected and reconfigured through a voted bus control configuration. Data is also shared between VMCs though a cross channel data link that is implemented in hardware and controlled by AlliedSignal's Fault Tolerant Executive (FTE). The FTE synchronizes processors within the VMC and synchronizes redundant VMCs to each other. The FTE provides an output-voting plane to detect, isolate and contain faults due to internal hardware or software faults and reconfigures the VMCs to accommodate these faults. Critical data in the 1553 messages are scheduled and synchronized to specific processing frames in order to minimize data latency. In order to achieve an open architecture, military and commercial off-the-shelf equipment is incorporated using common processors, standard VME backplanes and chassis, the VxWorks operating system, and MartixX for automatic code generation. The use of off-the-shelf tools and equipment helps reduce development time and enables software reuse. The open architecture allows for technology insertion, while the distributed modular elements allow for expansion to increased redundancy levels to meet the higher reliability goals of future RLVs.

Reichenfeld, Curtis J.↗

Testing of the Engineering Model Electrical Power Control Unit for the Fluids and Combustion Facility

The John H. Glenn Research Center at Lewis Field (GRC) in Cleveland, OH and the Sundstrand Corporation in Rockford, IL have designed and developed an Engineering Model (EM) Electrical Power Control Unit (EPCU) for the Fluids Combustion Facility, (FCF) experiments to be flown on the International Space Station (ISS). The EPCU will be used as the power interface to the ISS power distribution system for the FCF's space experiments'test and telemetry hardware. Furthermore. it is proposed to be the common power interface for all experiments. The EPCU is a three kilowatt 12OVdc-to-28Vdc converter utilizing three independent Power Converter Units (PCUs), each rated at 1kWe (36Adc @ 28Vdc) which are paralleled and synchronized. Each converter may be fed from one of two ISS power channels. The 28Vdc loads are connected to the EPCU output via 48 solid-state and current-limiting switches, rated at 4Adc each. These switches may be paralleled to supply any given load up to the 108Adc normal operational limit of the paralleled converters. The EPCU was designed in this manner to maximize allocated-power utilization. to shed loads autonomously, to provide fault tolerance. and to provide a flexible power converter and control module to meet various ISS load demands. Tests of the EPCU in the Power Systems Facility testbed at GRC reveal that the overall converted-power efficiency, is approximately 89% with a nominal-input voltage of 12OVdc and a total load in the range of 4O% to 110% rated 28Vdc load. (The PCUs alone have an efficiency of approximately 94.5%). Furthermore, the EM unit passed all flight-qualification level (and beyond) vibration tests, passed ISS EMI (conducted, radiated. and susceptibility) requirements. successfully operated for extended periods in a thermal/vacuum chamber, was integrated with a proto-flight experiment and passed all stability and functional requirements.

Kimnach, Greg L.↗

Robotic Precursor Missions for Mars Habitats

Infrastructure support for robotic colonies, manned Mars habitat, and/or robotic exploration of planetary surfaces will need to rely on the field deployment of multiple robust robots. This support includes such tasks as the deployment and servicing of power systems and ISRU generators, construction of beaconed roadways, and the site preparation and deployment of manned habitat modules. The current level of autonomy of planetary rovers such as Sojourner will need to be greatly enhanced for these types of operations. In addition, single robotic platforms will not be capable of complicated construction scenarios. Precursor robotic missions to Mars that involve teams of multiple cooperating robots to accomplish some of these tasks is a cost effective solution to the possible long timeline necessary for the deployment of a manned habitat. Ongoing work at JPL under the Mars Outpost Program in the area of robot colonies is investigating many of the technology developments necessary for such an ambitious undertaking. Some of the issues that are being addressed include behavior-based control systems for multiple cooperating robots (CAMPOUT), development of autonomous robotic systems for the rescue/repair of trapped or disabled robots, and the design and development of robotic platforms for construction tasks such as material transport and surface clearing.

Huntsberger, Terry↗

Computational Nanoelectronics and Nanotechnology at NASA ARC

Both physical and economic considerations indicate that the scaling era of CMOS will run out of steam around the year 2010. However, physical laws also indicate that it is possible to compute at a rate of a billion times present speeds with the expenditure of only one Watt of electrical power. NASA has long-term needs where ultra-small semiconductor devices are needed for critical applications: high performance, low power, compact computers for intelligent autonomous vehicles and Petaflop computing technology are some key examples. To advance the design, development, and production of future generation micro- and nano-devices, IT Modeling and Simulation Group has been started at NASA Ames with a goal to develop an integrated simulation environment that addresses problems related to nanoelectronics and molecular nanotechnology. Overview of nanoelectronics and nanotechnology research activities being carried out at Ames Research Center will be presented. We will also present the vision and the research objectives of the IT Modeling and Simulation Group including the applications of nanoelectronic based devices relevant to NASA missions.

Saini, Subhash↗

Managing Satellites

Integral Systems, Inc.'s EPOCH 2000 forms the core of NASA's Near Earth Asteroid Rendezvous (NEAR) mission's command and control center. EPOCH 2000, which allows ground operators to monitor and control satellites over a wide area network, owes part of its heritage from work completed to support Goddard Space Flight Center. The software automates telemetry processing, commanding, anomaly detection, and archiving collected data. The NEAR spacecraft, launched in February 1996, will rendezvous in early 1999 and orbit the Asteroid Eros for a year. Integral Systems also provided Low Earth Orbit Autonomous Ground Terminals (LEO-Ts) to NASA. The LEO-T is designed to make it easier and less expensive for principal investigators to obtain telemetry, tracking and control services for their science missions. The company products have supported well over 70 satellite missions aimed at scientific research, meteorology, or communications applications.

Source record↗

Computational Nanoelectronics and Nanotechnology at NASA ARC

Both physical and economic considerations indicate that the scaling era of CMOS will run out of steam around the year 2010. However, physical laws also indicate that it is possible to compute at a rate of a billion times present speeds with the expenditure of only one Watt of electrical power. NASA has long-term needs where ultra-small semiconductor devices are needed for critical applications: high performance, low power, compact computers for intelligent autonomous vehicles and Petaflop computing technolpgy are some key examples. To advance the design, development, and production of future generation micro- and nano-devices, IT Modeling and Simulation Group has been started at NASA Ames with a goal to develop an integrated simulation environment that addresses problems related to nanoelectronics and molecular nanotecnology. Overview of nanoelectronics and nanotechnology research activities being carried out at Ames Research Center will be presented. We will also present the vision and the research objectives of the IT Modeling and Simulation Group including the applications of nanoelectronic based devices relevant to NASA missions.

Saini, Subhash↗

Lightweight, Wearable, Metal Rubber Sensor

For autonomous health monitoring. NanoSonic, Inc., has developed comfortable garments with multiple integrated sensors designed to monitor astronaut health throughout long-duration space missions. The combined high electrical conductivity, low mechanical modulus, and environmental robustness of the sensors make them an effective, lightweight, and comfortable alternative to conventional use of metal wiring and cabling.

Hill, Andrea↗

Ground-Based Observing Campaign of Briz-M Debris

In 2015, NASA's Orbital Debris Program Office (ODPO) completed the installation of the Meter Class Autonomous Telescope (MCAT) on Ascension Island. MCAT is a 1.3m optical telescope designed with a fast tracking capability for observing orbital debris at all orbital regimes (Low-Erath orbits to Geosyncronous (GEO) orbits) from a low latitude site. This new asset is dedicated year-round for debris observations, and its location fills a geographical gap in the Ground-based Electro Optical Space Surveillance (GEODSS) network. A commercial off the shelf (COTS) research grade 0.4m telescope (named the Benbrook telescope) will also be installed on Ascension at the end of 2016. This smaller version is controlled by the same master software, designed by Euclid Research, and can be tasked to work independently or in concert with MCAT. Like MCAT, it has a the same suite of filters, a similar field of view, and a fast-tracking Astelco mount, and is also capable of tracking debris at all orbital regimes. These assets are well suited for targeted campagins or surveys of debris. Since 2013, NASA's ODPO has also had extensive access to the 3.8m infrared UKIRT telescope, located on Mauna Kea. At nearly 14,000-ft, this site affords excellent conditions for collecting both photometery and spectroscopy at near-IR (0.9 - 2.5 micrometers SWIR) and thermal-IR (8 - 25 micrometers; LWIR) regimes, ideal for investigating material properties as well as thermal characteristics and sizes of debris. For the purposes of understanding orbital debris, taking data in both survey mode as well as targeting individual objects for more in-depth characterizations are desired. With the recent break-ups of Briz-M rocket bodies, we have collected a suite of data in the optical, near-infrared, and mid-infrared of in-tact objects as well as those classified as debris. A break-up at GEO of a Briz-M rocket occurred in January, 2016, well timed for the first remote observing survey-campaign with MCAT. Access to the 3.8m UKIRT telescope has also allowed for investigating this break-up in the near-infrared at wavelengths where debris is often much more reflective, allowing for the potential detection of a smaller population of these debris. In addition, a suite of near-IR reflectance spectroscopy (0.8-2.5 micrometers) and thermal-IR (8-15 micrometers) of individual in-tact and debris Briz-M objects has been collected. Analysis of the survey data will be discussed.

Lederer, S. M.↗

A Structurally-Adaptive Framework for Distributed Airborne Sensing over Real-time Collaborative Information Sharing Networks

The emergence and maturation of wireless communication technologies continue to transform the aviation industry and are enabling new solutions to challenges faced by NASA’s Advanced Air Mobility (AAM) initiative. AAM is leading towards high-density autonomous aircraft operations in areas underserved by traditional aviation, such as over densely populated urban centers. In this paper, we build on concepts from Smart Spaces - where sensing, processing, and communication are embedded in an environment, and agents are operating within the space can exploit these capabilities in real-time through collaborative information sharing networks. Building from these concepts, we propose a framework to enable a dynamic, topologically-adaptive, and distributed estimation system for man-rated aviation to address challenges faced by autonomous AAM operations. This paper presents the initial concept of operations and system design for this framework, presents a mathematical formulation for abstraction of the problem, identifies requirements and constraints for operation, and presents algorithmic constructs and mathematical formalisms to demonstrate operation. The proposed framework will be evaluated on a regional AAM flight scenario and will focus on two initial applications: (1) GPS-free navigation supporting precision approach and landing (PAL), and (2) surveillance and conformance monitoring of aircraft in vertiport airspaces. Such approaches show promise in addressing gaps in current technologies needed to enable future AAM concepts, while promising greater capabilities, performance, robustness, and safety over current aviation systems and operations.

Structurally-Adaptive↗

A Structurally-Adaptive Framework for Distributed Airborne Sensing over Real-time Collaborative Information Sharing Networks

The emergence and maturation of wireless communication technologies continue to transform the aviation industry and are enabling new solutions to challenges faced by NASA’s Advanced Air Mobility (AAM) initiative. AAM is leading towards high-density autonomous aircraft operations in areas underserved by traditional aviation, such as over densely populated urban centers. In this paper, we build on concepts from distributed sensing and smart spaces - where sensing, processing, and communication are embedded in an environment, and agents are operating within the space can exploit these capabilities in real-time through collaborative information sharing networks. Building from these concepts, we propose a framework to enable a dynamic, topologically-adaptive, and distributed estimation system for man-rated aviation to address challenges faced by autonomous AAM operations. This paper presents the initial concept of operations and system design for this framework, presents a mathematical formulation for abstraction of the problem, identifies requirements and constraints for operation, and presents algorithmic constructs to demonstrate operation. The initial framework design will focus on supporting precision navigation and independent surveillance supporting conformance monitoring of aircraft in airspace corridors and vertiport airspaces. Preliminary results from this framework shows promise in addressing gaps in current technologies needed to enable future AAM concepts, while promising greater capabilities, performance, robustness, and safety over current aviation systems and operations.

Distributed sensing↗

A Software Architecture for Semiautonomous Robot Control

A software architecture has been developed to increase the safety and effectiveness with which tasks are performed by robots that are capable of functioning autonomously but sometimes are operated under control by humans. The control system of such a robot designed according to a prior software architecture has no way of taking account of how the environment has changed or what parts of a task were performed during an interval of control by a human, so that errors can occur (and, hence, safety and effectiveness jeopardized) when the human relinquishes control. The present architecture incorporates the control, task-planning, and sensor-based-monitoring features of typical prior autonomous-robot software architectures, plus features for updating information on the environment and planning of tasks during control by a human operator in order to enable the robot to track the actions taken by the operator and to be ready to resume autonomous operation with minimal error. The present architecture also provides a user interface that presents, to the operator, a variety of information on the internal state of the robot and the status of the task.

Kortenkamp, David↗

An Automated Optical Fiber Puller for Use in Low-Earth Orbit

With the slowdown in space station construction, limiting astronaut time for scientific experiments, an effort is being made to automate certain experiments. One such experiment is production of heavy metal fluoride fibers in the microgravity environment. Previous work by this author and others have shown that microgravity inhibits crystallization of ZBLAN glass. Thus an automated experiment has been designed. This experiment will consist of several elements, one which includes the use of an autonomous robot to initiate fiber pulling. The first element will be to melt the preform to eliminate crystals. The preform tip will then be heated to the viscosity necessary for fiber drawing. The robot will initiate the draw and attach the fiber end to the take-up reel. Once fiber pulling has commenced, sensors will be used to detect a fiber break, whereupon the robot can re-initiate the pulling process. The fiber will be coated with a polymer and the polymer cured with ultraviolet light. A laser micrometer will be used to monitor fiber diameter. The experiment is designed so that up to 10 preforms can be pulled into fiber during one flight. The apparatus will be mounted on a free-flying carrier which will be placed into low-earth orbit from the cargo bay of the space shuttle by the shuttle robot arm. The experiment can be started by a signal from the shuttle or from the ground via telescience. The experiment will proceed automatically using specially designed algorithms and will be monitored from the ground. The carrier will be picked up by the shuttle before return to earth.

Tucker, Dennis S.↗

Machine Learning-Based Predictive Analytics for Aircraft Engine Conceptual Design

Big data and artificial intelligence/machine learning are transforming the global business environment. Data is now the most valuable asset for enterprises in every industry. Companies are using data-driven insights for competitive advantage. With that, the adoption of machine learning-based data analytics is rapidly taking hold across various industries, producing autonomous systems that support human decision-making. This work explored the application of machine learning to aircraft engine conceptual design. Supervised machine-learning algorithms for regression and classification were employed to study patterns in an existing, open-source database of production and research turbofan engines, and resulting in predictive analytics for use in predicting performance of new turbofan designs. Specifically, the author developed machine learning-based analytics to predict cruise thrust specific fuel consumption (TSFC) and core sizes of high-efficiency turbofan engines, using engine design parameters as the input. The predictive analytics were trained and deployed in Keras, an open-source neural networks application program interface (API) written in Python, with Google’s TensorFlow (an open source library for numerical computation) serving as the backend engine. The promising results of the predictive analytics show that machine-learning techniques merit further exploration for application in aircraft engine conceptual design.

deep-learning↗

Aerocapture as an Option for Ice Giants Mission

Aerocapture is an atmospheric maneuver where the aerodynamic forces of the vehicle (lift and drag) are used to provide the 𝞓V needed to slow down from the approach hyperbolic trajectory to achieve the desired captured orbit around the target planet. The aeroassist capture provides a large savings in propulsion needed to change the velocity of the vehicle, since aerodynamic forces rather than propulsive systems provide the change in velocity. Aerocapture requires an integrated system level design, including thermal protection systems, actuator systems for aerodynamic modulation, and guidance and control systems that can autonomously command the change in the aeroassist forces. Although aerocapture has been proposed for many situations in the past, including Mars, Venus, Titan, Saturn, Uranus, and Neptune orbiters as well as for Earth demonstration missions, it has not been attempted on any missions. However, many studies in the past three decades that have considered aerocapture as a design option have concluded that there are large mass savings that come from using aeroassist forces rather than propulsive forces to put a spacecraft into a captured orbit. The benefits are destination dependent, but some of the largest mass savings occur for the Ice Giants planets. Due to the large hyperbolic velocities of interplanetary trajectories approaching Uranus and Neptune, large amount of propulsion must be used to put a spacecraft in science orbits around these planets. Aerocapture can reduce the propulsion needs by dissipating energy in the sizable atmospheres of Uranus and Neptune. NASA commissioned a detailed study analysis to quantify the benefits, if any, for use at Neptune. The study found that even having to provide a heat shield aerocapture could deliver 40% more payload than an all-propulsive vehicle, and also provides for a 3–4-year reduction in trip time. Mass savings are expected also at Uranus with an aerocapture mission. Additionally, more recent advances in thermal protection systems and guidance and control systems show a path to increase capabilities beyond those results. This paper will discuss the merits of including aerocapture as an option for an Ice Giants mission. The discussion will focus on the cost and mass savings of using aerocapture instead of propulsive burns for Ice Giants orbiter mission scenarios while also detailing a potential concept of operations and entry vehicle design. Finally, the talk will discuss more recent work that shows aerocapture design is possible without the development of any novel entry vehicle. Thus, aerocapture can significantly improve science capabilities for an Ice Giants mission.

Soumyo Dutta↗