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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,225 records · Page 68

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NASA NTRS1988

Vision sensing techniques in aeronautics and astronautics

The close relationship between sensing and other tasks in orbital space, and the integral role of vision sensing in practical aerospace applications, are illustrated. Typical space mission-vision tasks encompass the docking of space vehicles, the detection of unexpected objects, the diagnosis of spacecraft damage, and the inspection of critical spacecraft components. Attention is presently given to image functions, the 'windowing' of a view, the number of cameras required for inspection tasks, the choice of incoherent or coherent (laser) illumination, three-dimensional-to-two-dimensional model-matching, edge- and region-segmentation techniques, and motion analysis for tracking.

Hall, E. L.↗

NASA NTRS1989

Advanced technology for space communications, tracking, and robotic sensors

Technological advancements in tracking, communications, and robotic vision sensors are reviewed. The development of communications systems for multiple access, broadband, high data rate, and efficient operation is discussed. Consideration is given to the Tracking and Data Relay Satellite systems, GPS, and communications and tracking systems for the Space Shuttle and the Space Station. The use of television, laser, and microwave sensors for robotics and technology for autonomous rendezvous and docking operations are examined.

Krishen, Kumar↗

NASA NTRS1989

Missions to Mars - Assessing tomorrow's technology

The research and development of technologies necessary for the Mars Rover Sample Return (MRSR) mission are examined. Consideration is given to the use of aerobraking, autonomous rendezvous and docking, and an autonomous Mars lander. The development of a Mars Rover and the required sample acquisition, analysis and preservations capabilities of the Rover are discussed.

Thompson, Tina↗

NASA NTRS1990

Polyhedral Observation Cupola

Strong, lightweight structure includes facets with windows. Report describes concept for observation cupola for Space Station Freedom. Cupola used by crewmembers to observe docking of Space Shuttle, servicing of payloads, extravehicular activity, and other operations in which they could help by observing. Includes computer-generated pictures realistically depicting crewmembers' positions, workstation positions, and views through various windows.

Edelstein, Karen S.↗

NASA NTRS1990

Space Systems Integrated Simulation (SPASIS)

Complex program models everything on user-defined space station, from control gyros to mass effect of astronaut moving along strut. Other features include plume impingement, attitude control, propellant slosh, docking, and gravity.

Stecklein, J. M.↗

NASA NTRS1989

Conceptual design of a moving belt radiator shuttle-attached experiments: Technical requirement Document

The technical requirements for a shuttle-attached Moving Belt Radiator (MBR) experiment are defined. The MBR is an advanced radiator concept in which a rotating belt radiates thermal energy to space. The requirements for integrating the MBR experiment in the shuttle bay are discussed. Requirements for the belt material and working fluid are outlined along with some possible options. The proposed size and relationship to a full scale Moving Belt Radiator are defined. The experiment is defined with the primary goal of dynamic testing and a secondary goal of demonstrating the sealing and heat transfer characteristics. A perturbation system which will simulate a docking maneuver or other type of short term acceleration is proposed for inclusion in the experimental apparatus. A deployment and retraction capability which will aid in evaluating the dynamics of a belt during such a maneuver is also described. The proposed test sequence for the experiment is presented. Details of the conceptual design are not presented herein, but rather in a separate Final Report.

Aguilar, Jerry L.↗

NASA NTRS1989

Cooperative control of two active spacecraft during proximity operations

A cooperative autopilot is developed for the control of the relative attitude, relative position and absolute attitude of two maneuvering spacecraft during on orbit proximity operations. The autopilot consists of an open-loop trajectory solver which computes a nine dimensional linearized nominal state trajectory at the beginning of each maneuver and a phase space regulator which maintains the two spacecraft on the nominal trajectory during coast phases of the maneuver. A linear programming algorithm is used to perform jet selection. Simulation tests using a system of two space shuttle vehicles are performed to verify the performance of the cooperative controller and comparisons are made to a traditional passive target/active pursuit vehicle approach to proximity operations. The cooperative autopilot is shown to be able to control the two vehicle system when both the would be pursuit vehicle and the target vehicle are not completely controllable in six degrees of freedom. The cooperative controller is also shown to use as much as 37 percent less fuel and 57 percent fewer jet firings than a single pursuit vehicle during a simple docking approach maneuver.

Polutchko, Robert J.↗

NASA NTRS1990

Technology development, demonstration, and orbital support requirements for manned lunar and Mars missions

An overview of the critical technology needs and the Space Station Freedom (SSF) focused support requirements for the Office of Exploration's (OEXP) manned lunar and Mars missions is presented. Major emphasis is directed at the technology needs associated with the low earth orbit (LEO) transportation node assembly and vehicle processing functions required by the lunar and Mars mission flight elements. The key technology areas identified as crucial to support the LEO node function include in-space assembly and construction, in-space vehicle processing and refurbishment, space storable cryogenics, and autonomous rendezvous and docking.

Llewellyn, Charles P.↗

NASA NTRS1989

OMV mission simulator

The Orbital Maneuvering Vehicle (OMV) will be remotely piloted during rendezvous, docking, or proximity operations with target spacecraft from a ground control console (GCC). The real-time mission simulator and graphics being used to design a console pilot-machine interface are discussed. A real-time orbital dynamics simulator drives the visual displays. The dynamics simulator includes a J2 oblate earth gravity model and a generalized 1962 rotating atmospheric and drag model. The simulator also provides a variable-length communication delay to represent use of the Tracking and Data Relay Satellite System (TDRSS) and NASA Communications (NASCOM). Input parameter files determine the graphics display. This feature allows rapid prototyping since displays can be easily modified from pilot recommendations. A series of pilot reviews are being held to determine an effective pilot-machine interface. Pilots fly missions with nominal to 3-sigma dispersions in translational or rotational axes. Console dimensions, switch type and layout, hand controllers, and graphic interfaces are evaluated by the pilots and the GCC simulator is modified for subsequent runs. Initial results indicate a pilot preference for analog versus digital displays and for two 3-degree-of-freedom hand controllers.

Cok, Keith E.↗

NASA NTRS1989

A robotically constructed production and supply base on Phobos

PHOBIA Corporation is involved with the design of a man-tenable robotically constructed, bootstrap base on Mars' moon, Phobos. This base will be a pit-stop for future manned missions to Mars and beyond and will be a control facility during the robotic construction of a Martian base. An introduction is given to the concepts and the ground rules followed during the design process. Details of a base design and its location are given along with information about some of the subsystems. Since a major purpose of the base is to supply fuel to spacecraft so they can limit their fuel mass, mining and production systems are discussed. Surface support activities such as docks, anchors, and surface transportation systems are detailed. Several power supplies for the base are investigated and include fuel cells and a nuclear reactor. Tasks for the robots are defined along with descriptions of the robots capable of completing the tasks. Finally, failure modes for the entire PHOBIA Corporation design are presented along with an effects analysis and preventative recommendations.

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NASA NTRS1990

Hybrid vision activities at NASA Johnson Space Center

NASA's Johnson Space Center in Houston, Texas, is active in several aspects of hybrid image processing. (The term hybrid image processing refers to a system that combines digital and photonic processing). The major thrusts are autonomous space operations such as planetary landing, servicing, and rendezvous and docking. By processing images in non-Cartesian geometries to achieve shift invariance to canonical distortions, researchers use certain aspects of the human visual system for machine vision. That technology flow is bidirectional; researchers are investigating the possible utility of video-rate coordinate transformations for human low-vision patients. Man-in-the-loop teleoperations are also supported by the use of video-rate image-coordinate transformations, as researchers plan to use bandwidth compression tailored to the varying spatial acuity of the human operator. Technological elements being developed in the program include upgraded spatial light modulators, real-time coordinate transformations in video imagery, synthetic filters that robustly allow estimation of object pose parameters, convolutionally blurred filters that have continuously selectable invariance to such image changes as magnification and rotation, and optimization of optical correlation done with spatial light modulators that have limited range and couple both phase and amplitude in their response.

Juday, Richard D.↗

NASA NTRS1990

Space environment robot vision system

A prototype twin-camera stereo vision system for autonomous robots has been developed at Goddard Space Flight Center. Standard charge coupled device (CCD) imagers are interfaced with commercial frame buffers and direct memory access to a computer. The overlapping portions of the images are analyzed using photogrammetric techniques to obtain information about the position and orientation of objects in the scene. The camera head consists of two 510 x 492 x 8-bit CCD cameras mounted on individually adjustable mounts. The 16 mm efl lenses are designed for minimum geometric distortion. The cameras can be rotated in the pitch, roll, and yaw (pan angle) directions with respect to their optical axes. Calibration routines have been developed which automatically determine the lens focal lengths and pan angle between the two cameras. The calibration utilizes observations of a calibration structure with known geometry. Test results show the precision attainable is plus or minus 0.8 mm in range at 2 m distance using a camera separation of 171 mm. To demonstrate a task needed on Space Station Freedom, a target structure with a movable I beam was built. The camera head can autonomously direct actuators to dock the I-beam to another one so that they could be bolted together.

Wood, H. John↗

NASA NTRS1989

Modeling and control of flexible space stations (slew maneuvers)

Large orbiting space structures are expected to experience mechanical vibrations arising from several disturbing forces such as those induced by shuttle takeoff or docking and crew movements. The problem is considered of modeling and control of large space structures subject to these and other disturbing forces. The system consists of a (rigid) massive body, which may play the role of experimental modules located at the center of the space station and flexible configurations, consisting of several beams, forming the space structure. A complete dynamic model of the system was developed using Hamilton's principle. This model consists of radial equations describing the translational motion of the central body, rotational equations describing the attitude motions of the body and several beam equations governing the vibration of the flexible members (platform) including appropriate boundary conditions. In summary, the dynamics of the space structure is governed by a complex system of interconnected partial and ordinary differential equations. Using Lyapunov's approach the asymptotic stability of the space structure is investigated. For asymptotic stability of the rest state (nominal trajectory), feedback controls are suggested. In the investigation, stability of the slewing maneuvers is also considered. Several numerical results are presented for illustration of the impact of coupling and the effectiveness of the stabilizing controls. Some insight is provided into the complexity of modeling, analysis and stabilization of actual space structures.

Ahmed, N. U.↗

NASA NTRS1989

Neural networks in support of manned space

Many lobbyists in Washington have argued that artificial intelligence (AI) is an alternative to manned space activity. In actuality, this is the opposite of the truth, especially as regards artificial neural networks (ANNs), that form of AI which has the greatest hope of mimicking human abilities in learning, ability to interface with sensors and actuators, flexibility and balanced judgement. ANNs and their relation to expert systems (the more traditional form of AI), and the limitations of both technologies are briefly reviewed. A Few highlights of recent work on ANNs, including an NSF-sponsored workshop on ANNs for control applications are given. Current thinking on ANNs for use in certain key areas (the National Aerospace Plane, teleoperation, the control of large structures, fault diagnostics, and docking) which may be crucial to the long term future of man in space is discussed.

Werbos, Paul J.↗

NASA NTRS1989

Satellite servicer system flight demonstration program

A program to develop the capability of servicing satellites in remote locations, where a series of flight that will demonstrate autonomous rendezvous and docking, supervised autonomous Orbital Replacement Unit (ORU) exchange, supervised autonomous fluid transfer and, proximity operations for Space Station Freedom were planned, is described. The flight demonstrations are the results of several mission scenarios with complex technical objectives. Three Shuttle flights are planned to complete the multi-objective program. The major hardware elements of the program are described and discussed. Demonstration objectives and technical approaches to the flight demonstrations are discussed. Existing and developing technologies are assessed for applicability to the Satellite Servicer System (SSSFD) program.

James S. Moore↗

NASA NTRS1990

Space Station Based Microacceleration Experiment Platform

Normal Space Station Freedom activities, such as docking, astronauts' movement, equipment vibrations, and space station reboosts, exert forces on the structure, resulting in static or transient accelerations greater than many microgravity experiments can tolerate. A solution to this problem is to isolate experiments on a separate platform free from such disturbances. The Space Station Based Microacceleration Experiment Platform, a proposed solution to the Space Station microgravity experiment problem is described. It is modular in design and can be telerobotically assembled and operated. The Microacceleration Experiment Platform (MEP) consists of a minimum configuration platform to which power, propulsion, propellant, and experiment modules are added. The platform's layout is designed to take maximum advantage of the microgravity field structure in orbit.

Barber, Katy↗

NASA NTRS1990

Dynamic analysis of space-related linear and non-linear structures

In order to be cost effective, space structures must be extremely light weight, and subsequently, very flexible structures. The power system for Space Station Freedom is such a structure. Each array consists of a deployable truss mast and a split blanket of photovoltaic solar collectors. The solar arrays are deployed in orbit, and the blanket is stretched into position as the mast is extended. Geometric stiffness due to the preload make this an interesting non-linear problem. The space station will be subjected to various dynamic loads, during shuttle docking, solar tracking, attitude adjustment, etc. Accurate prediction of the natural frequencies and mode shapes of the space station components, including the solar arrays, is critical for determining the structural adequacy of the components, and for designing a dynamic controls system. The process used in developing and verifying the finite element dynamic model of the photo-voltaic arrays is documented. Various problems were identified, such as grounding effects due to geometric stiffness, large displacement effects, and pseudo-stiffness (grounding) due to lack of required rigid body modes. Analysis techniques, such as development of rigorous solutions using continuum mechanics, finite element solution sequence altering, equivalent systems using a curvature basis, Craig-Bampton superelement approach, and modal ordering schemes were utilized. The grounding problems associated with the geometric stiffness are emphasized.

Bosela, Paul A.↗

NASA NTRS1990

Biconic cargo return vehicle with an advanced recovery system. Volume 1: Conceptual design

The conceptual design of the biconic Cargo Return Vehicle (CRV) is presented. The CRV will be able to meet all of the Space Station Freedom (SSF's) resupply needs. Worth note is the absence of a backup recovery chute in case of Advanced Recovery System (ARS) failure. The high reliability of ram-air parachutes does not warrant the penalty weight that such a system would create on successful missions. The CRV will launch vertically integrated with an Liquid Rocket Booster (LRB) vehicle and meets all NASA restrictions on fuel type for all phases of the mission. Because of the downscaled Orbital Maneuvering Vehicle (OMV) program, the CRV has been designed to be able to transfer cargo by docking directly to the Space Station Freedom as well as with OMV assistance. The CRV will cover enough crossrange to reach its primary landing site, Edwards Airforce Base, and all secondary landing sites with the exception of one orbit. Transportation back to KSC will be via the Boeing Super Guppy. Due to difficulties with man-rating the CRV, it will not be used in a CERV role. A brief summary of the CRV's specifications is given.

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