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At least 505 records · Page 28

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NASA NTRS1978

Can low-cost VOR and Omega receivers suffice for RNAV - A new computer-based navigation technique

It is shown that although RNAV is particularly valuable for the personal transportation segment of general aviation, it has not gained complete acceptance. This is due, in part, to its high cost and the necessary special-handling air traffic control. VOR/DME RNAV calculations are ideally suited for analog computers, and the use of microprocessor technology has been suggested for reducing RNAV costs. Three navigation systems, VOR, Omega, and DR, are compared for common navigational difficulties, such as station geometry, siting errors, ground disturbances, and terminal area coverage. The Kalman filtering technique is described with reference to the disadvantages when using a system including standard microprocessors. An integrated navigation system, using input data from various low-cost sensor systems, is presented and current simulation studies are noted.

Hollaar, L. A.↗

NASA NTRS1979

Evaluation of the navigation performance of shipboard-VTOL-landing guidance systems

The objective of this study was to explore the performance of a VTOL aircraft landing approach navigation system that receives data (1) from either a microwave scanning beam (MSB) or a radar-transponder (R-T) landing guidance system, and (2) information data-linked from an aviation facility ship. State-of-the-art low-cost-aided inertial techniques and variable gain filters were used in the assumed navigation system. Compensation for ship motion was accomplished by a landing pad deviation vector concept that is a measure of the landing pad's deviation from its calm sea location. The results show that the landing guidance concepts were successful in meeting all of the current Navy navigation error specifications, provided that vector magnitude of the allowable error, rather than the error in each axis, is a permissible interpretation of acceptable performance. The success of these concepts, however, is strongly dependent on the distance measuring equipment bias. In addition, the 'best possible' closed-loop tracking performance achievable with the assumed point-mass VTOL aircraft guidance concept is demonstrated.

Mcgee, L. A.↗

NASA NTRS1979

Algorithms and logic for incorporating ILS NASA TCV B-737 airplane area navigation system

The algorithms and logic for use in the implementation of instrument landing system (ILS) localizer deviation signals for the generation of navigation and guidance information are presented. The navigation position estimates, based on range information from a randomly chosen distance measuring equipment (DME) and ILS localizer deviation information, are illustrated. The ILS volumetric coverage and DME geometric checks are described and their addition to area navigation systems with minimum software modification are discussed.

Knox, C. E.↗

NASA NTRS1979

Navigation systems for approach and landing of VTOL aircraft

The formulation and implementation of navigation systems used for research investigations in the V/STOLAND avionics system are described. The navigation systems prove position and velocity in a cartestian reference frame aligned with the runway. They use filtering techniques to combine the raw position data from navaids (e.g., TACAN, MLS) with data from onboard inertial sensors. The filtering techniques which use both complementary and Kalman filters, are described. The software for the navigation systems is also described.

Schmidt, S. F.↗

NASA NTRS1979

Viking Navigation: Introduction

The design, control, and reconstruction of the flight paths of all four Viking vehicles is presented. The specification of requirements on the flight hardware is described along with the navigation strategies, procedures, operational software, and the inflight navigation. Features of the Viking navigation discussed include the precise determination of the spacecraft trajectories, prediction of the trajectories, design of the propulsive maneuvers required to effect the necessary trajectory changes, and calculation of the Lander descent guidance parameters.

Oneil, W. J.↗

NASA NTRS1980

Shuttle OFT Level C navigation requirements

Detailed requirements for the orbital operations computer loads, OPS 2, and OPS 8 are given. These requirements represent the total on-orbit/rendezvous navigation baseline requirements for the following principal functions: on-orbital/rendezvous navigation sequencer; on-orbit/rendezvous UPP sequencer; on-orbit rendezvous navigation; on-orbit prediction; on-orbit user parameter processing; and landing Site update.

Source record↗

NASA NTRS1980

Navigation accuracy analysis for the Halley flyby phase of a dual comet mission using ion drive

A dual comet (Halley Flyby/Tempel 2 Rendezvous) mission, making use of the solar electric propulsion system, is under consideration for a 1985 launch. This paper presents navigation accuracy analysis results for the Halley flyby phase of this mission. Orbit determination and guidance accuracies are presented for the baseline navigation strategy, along with the results of a number of sensitivity studies involving parameters such as data frequencies, data accuracies, ion drive thrust vector errors, comet ephemeris uncertainties, time lags associated with data processing and command sequence generation, probe release time, and navigation coast arc duration.

Wood, L. J.↗

NASA NTRS1980

Automated optical navigation with application to Galileo

This paper presents an overview of an automated optical navigation (AON) system, a lower-cost, faster, earth-based stepping stone to onboard systems. AON provides estimation (orbit determination) and maneuver subsystems which are automatically linked to provide the fast response required by the Galileo mission, AON's first user. A real-time interactive executive schedules the subsystems to run concurrently or sequentially and enables interactive computer-graphics displays designed to speed evaluation and certification of navigation solutions. A compact trajectory integrator provides a favorable combination of speed and accuracy. Resident on a low-cost minicomputer and coded primarily in HAL/S, the NASA standard language for flight software, AON approaches a prototype for autonomous onboard navigation systems of the future.

Klumpp, A. R.↗

NASA NTRS1980

An analysis of GDOP in global positioning system navigation

The accuracy of user navigation fix based on the NAVSTAR global positioning system is described. The trace of this matrix serves as a convenient navigation performance index and the square root of the trace is called geometric dilution of precision (GDOP). Certain theoretical results concerning the general properties of the navigation performance are derived. An efficient algorithm for the computation of GDOP is given. Applications of the results are illustrated by numerical examples.

Fang, B. T.↗

NASA NTRS1980

Development of a computer program data base of a navigation aid environment for simulated IFR flight and landing studies

A general aviation single pilot instrument flight rule simulation capability was developed. Problems experienced by single pilots flying in IFR conditions were investigated. The simulation required a three dimensional spatial navaid environment of a flight navigational area. A computer simulation of all the navigational aids plus 12 selected airports located in the Washington/Norfolk area was developed. All programmed locations in the list were referenced to a Cartesian coordinate system with the origin located at a specified airport's reference point. All navigational aids with their associated frequencies, call letters, locations, and orientations plus runways and true headings are included in the data base. The simulation included a TV displayed out-the-window visual scene of country and suburban terrain and a scaled model runway complex. Any of the programmed runways, with all its associated navaids, can be referenced to a runway on the airport in this visual scene. This allows a simulation of a full mission scenario including breakout and landing.

Bergeron, H. P.↗

NASA NTRS1980

A computer system for geosynchronous satellite navigation

A computer system specifically designed to estimate and predict Geostationary Operational Environmental Satellite (GOES-4) navigation parameters using Earth imagery is described. The estimates are needed for spacecraft maneuvers while prediction provide the capability for near real-time image registration. System software is composed of four functional subsystems: (1) data base management; (2) image processing; (3) navigation; and (4) output. Hardware consists of a host minicomputer, a cathode ray tube terminal, a graphics/video display unit, and associated input/output peripherals. System validity is established through the processing of actual imagery obtained by sensors on board the Synchronous Meteorological Satellite (SMS-2). Results indicate the system is capable of operationally providing both accurate GOES-4 navigation estimates and images with a potential registration accuracy of several picture elements (pixels).

Koch, D. W.↗

NASA NTRS1981

Navigation accuracy analysis for a Halley intercept mission

A ballistic intercept mission to Comet Halley is currently under consideration by the United States. This paper describes the navigation system and the navigation strategy which would be employed in such a mission, assuming a launch in the summer of 1985 and an arrival in March of 1986. Spacecraft comet-relative orbit determination accuracies are presented as functions of time for the baseline navigation strategy, along with the results of a number of parametric sensitivity studies involving parameters such as data frequencies, data accuracies, stochastic acceleration levels, cometary ephemeris uncertainties, maneuver execution errors, and encounter date.

Wood, L. J.↗

NASA NTRS1980

Navigation errors encountered using weather-mapping radar for helicopter IFR guidance to oil rigs

In 1978 a joint NASA-FAA helicopter flight test was conducted to examine the use of weather-mapping radar for IFR guidance during landing approaches to oil rig helipads. The following navigation errors were measured: total system error, radar-range error, radar-bearing error, and flight technical error. Three problem areas were identified: (1) operational problems leading to pilot blunders, (2) poor navigation to the downwind final approach point, and (3) pure homing on final approach. Analysis of these problem areas suggests improvement in the radar equipment, approach procedure, and pilot training, and gives valuable insight into the development of future navigation aids to serve the off-shore oil industry.

Phillips, J. D.↗

NASA NTRS1980

Low-frequency radio navigation for the Army's Mobile Automated Field Instrumentation System /MAFIS/

The Jet Propulsion Laboratory is engaged in the early phases of conceptual, preliminary design, and feasibility demonstration studies leading to determination of a design and implementation of the Army's proposed Mobile Automated Field Instrumentation System (MAFIS). An overview is provided of the current design concept for an experimental radio navigation subsystem to be implemented in the field as a part of the MAFIS study effort. Objectives of MAFIS include mobility, field-ruggedness and longevity of equipment, and low acquisition and life-cycle costs. The navigation subsystem comprises a 4-station radio transmitter network, plus the navigation receivers, network monitoring receivers and communications links, and interface to the command/control 'central' for transmitter status monitoring. Attention is given to accuracy goals, radio propagation effects, transmitter arrangement, radio-frequency allocations, position initialization and lane resolution, and transmitter and receiver functions.

Wallis, D. E.↗

NASA NTRS1981

Deep space navigation systems and operations

The history of the deep space navigation system developed by NASA is outlined. Its application to Mariner, Viking and Pioneer missions is reviewed. Voyager navigation results for Jupiter and Saturn are commented on and velocity correction in relation to fuel expenditure and computer time are discussed. The navigation requirements of the Gahleo and Venus orbiting imaging radar (VOIR) missions are assessed. The measurement and data processing systems are described.

Jordan, J. F.↗

NASA NTRS1981

Mathematical specifications of the Onboard Navigation Package (ONPAC) simulator (revision 1)

The mathematical theory of the computational algorithms employed in the onboard navigation package system is described. This system, which simulates an onboard navigation processor, was developed to aid in the design and evaluation of onboard navigation software. The mathematical formulations presented include the factorized UDU(T) form of the extended Kalman filter, the equations of motion of the user satellite, the user clock equations, the observation equations and their partial derivatives, the coodinate transformations, and the matrix decomposition algorithms.

Dunham, J. B.↗

NASA NTRS1980

Interplanetary beacon for deep space navigation

The utilization of the Viking lander as a beacon for navigating the Galileo spacecraft for its Mars flyby is investigated. Covariance analyses show that the improvement in the flyby navigation accuracy is significant compared with the conventional radiometric navigation. A validation experiment using Viking lander and orbiter indicates that the expected accuracy can be obtained.

Ananda, M. P.↗

NASA NTRS1983

Area navigation implementation for a microcomputer-based LORAN-C receiver

Engineering performed to make LORAN-C a more useful and practical navigation system for general aviation is described. Development of new software, and implementation of this software on a (MOS6502) microcomputer to provide high quality practical area navigation information directly to the pilot and considered. Flight tests were performed specifically to examine the efficacy of this new software. Final results were exceptionally good and clearly demonstrate the merits of this new LORAN-C area navigation system.

Oguri, F.↗