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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 469 records · Page 26
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Instrumentation in astronomy VII; Proceedings of the Meeting, Tucson, AZ, Feb. 13-17, 1990

The topics discussed include IR detectors and instrumentation, detectors, other instrumentation, optical instrumentation, and space instrumentation. Papers are presented on the IR spectrometer/imager for the ESO VLT, the fiber-coupled high-resolution IR array spectrometer for the Kuiper Airborne Observatory, the Balloon-Borne Infrared Telescope for FIR spectroscopy, and a simple transputer-based CCD camera controller. Attention is given to CCD guidance system for William Herschel Telescope, the New Technology Telescope control/acquisition system as a prototype for the VLT, a control system for spincasting 8-m borosilicate honeycomb mirrors, echelle spectrographs for 8-m class telescopes, and fiber spectroscopy at Palomar Observatory. Other papers are on the Kitt Peak National Observatory fiber actuator device, a two-star photoelectric photometer, an ultrahigh-resolution XUV spectroheliograph, an optical monitor for X-ray satellites, and large-format electrographic and array detectors for a space Schmidt imaging telescope.

Crawford, David L.↗
NASA NTRS1991

Status of automated nap-of-the-earth rotorcraft guidance

The status of automated nap-of-the-earth (NOE) flight guidance is discussed by examining two current research efforts that approach the problem of performing obstacle avoidance along a pre-planned course from different perspectives. The first, a real-time guidance system developed by Systems Technology Inc., focuses on the issue of pilot acceptable maneuvers, under the assumption of an ideal, but nonrealizable, obstacle detection system. The second, a system created at NASA Ames, concentrates on the utilization of realistic on-board sensor data for obstacle detection and avoidance-maneuver decisions. This paper examines the strengths and weaknesses of these two approaches, and how they might complement each other. The goal is an automatic NOE system that is both acceptable to pilots and capable of making intelligent use of realistic sensor information and path-selection logic.

Coppenbarger, Richard A.↗
NASA NTRS1992

Vision-based obstacle detection for rotorcraft flight

An obstacle detection approach to rotorcraft flight is described which is based on feature tracking and recursive range estimation. Flight characteristics are taken into account. A range map derived on the basis of this approach provides an advisory display to the pilot and can serve as input to an automatic obstacle-avoidance guidance system. A NASA CH-47 Chinook helicopter was used to develop an image and rotorcraft flight data base for verification of obstacle detection concepts. The performance of the passive range estimation algorithms is demonstrated using both laboratory image and flight image data.

Sridhar, Banavar↗
NASA NTRS1991

New developments in astrodynamics algorithms for autonomous rendezvous

A the core of any autonomous rendezvous guidance system must be two algorithms for solving Lambert's and Kepler's problems, the two fundamental problems in classical astrodynamics. Lambert's problem is to determine the trajectory connecting specified initial and terminal position vectors in a specified transfer time. The solution is the initial and terminal velocity vectors. Kepler's problem is to determine the trajectory that stems from a given initial state (position and velocity). The solution is the state of an earlier or later specified time. To be suitable for flight software, astrodynamics algorithms must be totally reliable, compact, and fast. Although solving Lambert's and Kepler's problems has challenged some of the world's finest minds for over two centuries, only in the last year have algorithms appeared that satisfy all three requirements just stated. This paper presents an evaluation of the most highly regarded Lambert and Kepler algorithms.

Klumpp, Allan R.↗
NASA NTRS1993

Ultrasonic Polishing

The ultrasonic polishing process makes use of the high-frequency (ultrasonic) vibrations of an abradable tool which automatically conforms to the work piece and an abrasive slurry to finish surfaces and edges on complex, highly detailed, close tolerance cavities in materials from beryllium copper to carbide. Applications range from critical deburring of guidance system components to removing EDM recast layers from aircraft engine components to polishing molds for forming carbide cutting tool inserts or injection molding plastics. A variety of materials including tool steels, carbides, and even ceramics can be successfully processed. Since the abradable tool automatically conforms to the work piece geometry, the ultrasonic finishing method described offers a number of important benefits in finishing components with complex geometries.

Gilmore, Randy↗
NASA NTRS1992

HUD Guidance for the ASKA Experimental STOL Aircraft using Radar Position Information

The paper describes a high performance HUD guidance system installed on the experimental powered-lift STOL aircraft Aska. Since the maiden flight in October 1985, the HUD system has been used in all the flight tests. The HUD has an accurate flight path symbol generated by inertial velocity from the IRS which is updated by up-linked precision radar position data. The flight path symbol is very useful for precise approach and flare control for Aska which has large ground effects. A synthetic runway is also presented, which is conformal with the real runway, using the position data from the ground tracking radar system. Under instrument meteorological conditions, the pilot can approach and land using the HUD synthetic runway as well as in visual meteorological conditions. The HUD system proved to be a valuable aid to the pilot for all the Aska flight tests. A NASA Ames Research Center test pilot demonstrated touch down accuracy of less than 8 meters (peak to peak) for a series of three landings.

Yazawa, Kenji↗
NASA NTRS1992

Terrain tracking for lander guidance using binary phase-only spatial filters

We demonstrate the use of binary phase-only spatial filters (BPOFs) for tracking target sites through a sequence of gray-scale terrain images. The filters are demonstrated in a closed loop guidance system for a laboratory lander mockup. Images of a 3D terrain board taken by the lander's video camera are preprocessed to produce binary intensity contour maps of a simulated planetary surface. A BPOF is made from a section of the current preprocessed image centered on the exact desired landing site. After the lander has descended to a lower altitude, the BPOF is correlated with a new image. The position of the correlation peak is used in making the next filter and to guide the lander so as to recenter the landing site in the camera's view. We present testbed results of the accuracy with which a site may be tracted from orbit to landing, and the maximum scale, translation, and rotation which can be tolerated between subsequent images. Application of the results to NASA's proposed Mars Rover Sample Return (MRSR) and Mars Environmental Survey (MESUR) missions is discussed.

Reid, Max B.↗
NASA NTRS1993

The development and flight test of a deployable precision landing system for spacecraft recovery

A joint NASA Dryden Flight Research Facility and Johnson Space Center program was conducted to determine the feasibility of the autonomous recovery of a spacecraft using a ram-air parafoil system for the final stages of entry from space that included a precision landing. The feasibility of this system was studied using a flight model of a spacecraft in the generic shape of a flattened biconic which weighed approximately 150 lb and was flown under a commercially available, ram-air parachute. Key elements of the vehicle included the Global Positioning System guidance for navigation, flight control computer, ultrasonic sensing for terminal altitude, electronic compass, and onboard data recording. A flight test program was used to develop and refine the vehicle. This vehicle completed an autonomous flight from an altitude of 10,000 ft and a lateral offset of 1.7 miles which resulted in a precision flare and landing into the wind at a predetermined location. At times, the autonomous flight was conducted in the presence of winds approximately equal to vehicle airspeed. Several techniques for computing the winds postflight were evaluated. Future program objectives are also presented.

Sim, Alex G.↗
NASA NTRS1990

Knowledge/geometry-based Mobile Autonomous Robot Simulator (KMARS)

Ongoing applied research is focused on developing guidance system for robot vehicles. Problems facing the basic research needed to support this development (e.g., scene understanding, real-time vision processing, etc.) are major impediments to progress. Due to the complexity and the unpredictable nature of a vehicle's area of operation, more advanced vehicle control systems must be able to learn about obstacles within the range of its sensor(s). A better understanding of the basic exploration process is needed to provide critical support to developers of both sensor systems and intelligent control systems which can be used in a wide spectrum of autonomous vehicles. Elcee Computek, Inc. has been working under contract to the Flight Dynamics Laboratory, Wright Research and Development Center, Wright-Patterson AFB, Ohio to develop a Knowledge/Geometry-based Mobile Autonomous Robot Simulator (KMARS). KMARS has two parts: a geometry base and a knowledge base. The knowledge base part of the system employs the expert-system shell CLIPS ('C' Language Integrated Production System) and necessary rules that control both the vehicle's use of an obstacle detecting sensor and the overall exploration process. The initial phase project has focused on the simulation of a point robot vehicle operating in a 2D environment.

Cheng, Linfu↗
NASA NTRS1997

Dynamical Models for Sloshing Dynamics of Helium 2 Under Low-G Conditions

Coupling of sloshing dynamics within a partially filled rotating dewar of superfluid helium 2 with spacecraft dynamics are investigated in response to the realistic environmental disturbance forces and torques acting on the spacecraft during normal operation. This study investigates: (1) the rotating bubble of superfluid helium 2 reacting to combined environmental disturbances, including gravity gradient, aerodynamic, and magnetic forces and torques; (2) characteristics of slosh reaction forces and torques coupling with spacecraft dynamics; (3) the contribution of slosh dynamics to over-all spacecraft dynamics; and (4) activating of attitude and translation control system. The numerical computation of sloshing dynamics is based on the rotational frame, while the spacecraft dynamics is associated with non-rotational frame. Results show that the contributions of spacecraft dynamics are driven by the environmental disturbances coupling with slosh dynamics. Without considering the effects of environmental disturbances-driven slosh dynamics acting on spacecraft coupling with the spacecraft dynamics may lead to the wrong results for the development of spacecraft system guidance and attitude control techniques.

Hung, R. J.↗
NASA NTRS1998

Airborne Laser Altimetric Monitoring of the Rapid Evolution of Topography in the Long Valley, CA, Caldera

A consortium of investigators from several universities and Government agencies have conducted a series of aircraft topographic surveys over the Long Valley caldera, California. The region has a geologic history of extensive volcanism, and its central dome has recently been undergoing resurgent uplift episodes of up to 4 cm per year, a deformation rate that is still continuing. These surveys were conducted from the NASA WFF T39 jet aircraft, outfitted with a nadir-profiling altimetric laser (ATLAS), a GPS guidance system for in-flight precision navigation, two P-code GPS receivers, a Litton LTN92 inertial unit for attitude determination, and both video and still-frame aerial cameras. In addition, two base-station GPS receivers were deployed for post-flight differential navigation, complementing the permanent GPS station operated on the resurgent dome by JPL, and a kinematic automobile survey of roads crossing the area was conducted, thereby complementing the JPL kinematic GPS surveys of some of the same roads. Precision flying yielded multiple profiles along nearly identical paths, including crossing profiles over selected locations within the caidera and calibration flights over Mono Lake, and Lake Crowley. Data from the most recent survey in 1995 are at this time still being reduced, but the standard error of the mean is very low (< 3 mm), due to the high number of crossover points. We thus intend to evaluate the technique for measuring systematic changes in the dome height over time.

Rundle, John↗
NASA NTRS1999

Development and Feasibility Testing of Image-Guided Minimally Invasive Tissue for Diagnosis Treatment of Benign and Malignant Breast Disease

Dr. Robert Mah and Dr. Stefanie Jeffrey worked on the development of the NASA Smart Probe in its application as a device to measure and interpret physiologic and image-based parameters of breast tissue. To date the following has been achieved: 1 . Choice of candidate sensors to be tested in breast tissue. 2. Preliminary designs for probe tip, specifically use of different tip shapes, cutting edges, and sensor configuration. 3. Design of sonographic guidance system. 4. Design of data extraction and analysis tool using scanned information of images of the breast tissue to provide a higher dimension of information for breast tissue characterization and interpretation. 5. Initial ex-vivo (fruit and tofu) and in-vivo (rodent) testing to confirm unique substance and tissue characterization by the Smart Probe software.

Jeffrey, Stefanie S.↗
NASA NTRS2000

Scientific American Inventions From Outer Space: Everyday Uses For NASA Technology

The purpose of this book is to present some of the inventions highlighted in the yearly publication of the National Aeronautics and Space Administration (NASA) Spinoff. These inventions cover a wide range, some of which include improvements in health, medicine, public safety, energy, environment, resource management, computer technology, automation, construction, transportation, and manufacturing technology. NASA technology has brought forth thousands of commercial products which include athletic shoes, portable x-ray machines, and scratch-resistant sunglasses, guidance systems, lasers, solar power, robotics and prosthetic devices. These products are examples of NASA research innovations which have positively impacted the community.

Baker, David↗
NASA NTRS1983

Noise Abatement

SMART, Sound Modification and Regulated Temperature compound, is a liquid plastic mixture with exceptional energy and sound absorbing qualities. It is derived from a very elastic plastic which was an effective noise abatement material in the Apollo Guidance System. Discovered by a NASA employee, it is marketed by Environmental Health Systems, Inc. (EHS). The product has been successfully employed by a diaper company with noisy dryers and a sugar company with noisy blowers. The company also manufactures an audiometric test booth and acoustical office partitions.

Source record↗
NASA NTRS1961

Study of the Use of a Terminal Controller Technique for Reentry Guidance of a Capsule-Type Vehicle

A study has been made of the use o f a terminal controller technique i n the guidance of a high-drag, variable-lift reentry vehicle to a desired landing point. The technique uses linearized equations of motion attained by the perturbation of the dependent variables from those of a reference trajectory. The guidance system continuously predicts the terminal range error and uses this error to control the angle of attack of the vehicle in an on-off manner until the predicted range error is within +-O.1 degrees of the required arc or +-6.9 miles.

Foudriat, Edwin C.↗
NASA NTRS2004

Portable Wireless LAN Device and Two-Way Radio Threat Assessment for Aircraft VHF Communication Radio Band

This document summarizes the safety analysis performed on a Flight Guidance System (FGS) requirements model. In particular, the safety properties desired of the FGS model are identified and the presence of the safety properties in the model is formally verified. Chapter 1 provides an introduction to the entire project, while Chapter 2 gives a brief overview of the problem domain, the nature of accidents, model based development, and the four-variable model. Chapter 3 outlines the approach. Chapter 4 presents the results of the traditional safety analysis techniques and illustrates how the hazardous conditions associated with the system trace into specific safety properties. Chapter 5 presents the results of the formal methods analysis technique model checking that was used to verify the presence of the safety properties in the requirements model. Finally, Chapter 6 summarizes the main conclusions of the study, first and foremost that model checking is a very effective verification technique to use on discrete models with reasonable state spaces. Additional supporting details are provided in the appendices.

Nguyen, Truong X.↗
NASA NTRS2004

Autonomous Guidance of Agile Small-scale Rotorcraft

This report describes a guidance system for agile vehicles based on a hybrid closed-loop model of the vehicle dynamics. The hybrid model represents the vehicle dynamics through a combination of linear-time-invariant control modes and pre-programmed, finite-duration maneuvers. This particular hybrid structure can be realized through a control system that combines trim controllers and a maneuvering control logic. The former enable precise trajectory tracking, and the latter enables trajectories at the edge of the vehicle capabilities. The closed-loop model is much simpler than the full vehicle equations of motion, yet it can capture a broad range of dynamic behaviors. It also supports a consistent link between the physical layer and the decision-making layer. The trajectory generation was formulated as an optimization problem using mixed-integer-linear-programming. The optimization is solved in a receding horizon fashion. Several techniques to improve the computational tractability were investigate. Simulation experiments using NASA Ames 'R-50 model show that this approach fully exploits the vehicle's agility.

Mettler, Bernard↗