摘要:

AbstractSatellite‐star optical navigation, a new spacecraft navigation technique has been successfully demonstrated during Mariner 9's approach to Mars in mid‐November of 1971. As Mariner 9 approached Mars, 21 TV pictures of its satellites, Phobos and Deimos, were taken and transmitted to earth. On earth, these pictures were carefully processed in order to locate the positions of the bright satellites against the relatively faint star background. These position fixes were used to obtain more accurate knowledge of Mariner 9's path with respect to Mars and its satellites. The accuracy of the new navigation technique has been confirmed by comparison with the standard radio navigation results on Mariner 9. This successful demonstration of satellite‐star optical navigation is the culmination of over 2 years of development work at JPL sponsored by NASA's Office of Aeronautics and Space Technology (OAST). NASA now has developed and demonstrated a prototype of a more accurate navigation system, using onboard measurements, which is essential to meeting the challenging requirements of future missions such as the multi‐planet gravity‐assisted outer planet missions. This paper describes the objectives and performance of the pre‐flight and real time activities leading to the successful demonstration of satellite‐star na

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01698.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractAvehicle dependenton navigation or communication radio receivers has to avoid a radio‐noise contaminated area. Equations and curves are presented which are useful in analyzing the navigational problem when the requirement is to avoid areas contaminated by a radio‐noise source. For preliminary analysis purposes, an adequate geometric description of a noise area is completely determined by only two parameters, one of which is a simple separation distance and the other a parameter which has been referred to, by some writers, as “equivalent received excess required signal to noise power ratio.” A literature search has not revealed pertinent predecessor treatment of this subje

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01699.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThis paper describesa worldwide distress alarm, identification, and position location system which could be operational within three years. The Global Rescue Alarm Net (GRAN) feasibility tests conducted by the Naval Air Test Center utilized a NASA Omega Position Locating Equipment (OPLE) package modified for UHF operation. Results of low power (ERP) tests with four satellites are discussed. Follow‐on tests already funded by a Navy/NASA/Coast Guard joint program to develop system specifications are describe

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01700.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractSight reductionprocedures in marine navigation have been traditional for nearly a century and a half, just as the marine sextant, itself, has been essentially the same design for 250 years. The reduction of each sextant sight to true azimuth and altitude intercept requires the use of standard forms, The Nautical Almanac, and several volumes of sight reduction tables. The procedure is tedious and time consuming, and errors in data selection and arithmetic are common. A low‐cost, specialized, small portable computer that operates with the sextant can be developed to relieve the navigator of his calculation tedium and blunders and improve his navigation accuracy. The design of such a small computer is feasible today. The logic and a functional computer program have been developed that combines the necessary data and spherical trigonometric equations to reduce the altitude measurements of the stars to data ready for plotting by the navigator.This paper will discuss the new digital readout day/night marine sextant which is part of the concept of the portable sextant‐computer system, the development of the program for the computer, and its application to solve navigation problems. Furthermore, use of the portable computer will be shown to be applicable to all fields of navigation, although the current development centers around marine navigat

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01701.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractThe mature eraof space exploration, now opening to us, will heavily involve the use of unmanned vehicles for both fly‐bys and the exploration of planetary surfaces. Consequently, the subject, ‘navigation in space’, should be applied to both spacecraft and the vehicles which would traverse the surfaces of planets being explored. This paper focuses upon the potential application of several modern developments, ‘fuzzy algorithms' and ‘artificial intelligence’ to navigation in space. It relates these topics to the realities of long distance communications and data management problems which will be encountered in future deep spa

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01702.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractAtechnique to identifyand isolate gyro drift within a two‐IMU configuration is presented. The unique gyro drift modulation of the Delco Electronics Carousel V is utilized. The Carousel V system differs from conventional gimballed systems in that four of the inertial instruments (xandyaccelerometers and gyros) are mounted on a rotating (1 rpm) instrument cluster. Excessive drift of any gyro results in a distinct combination of sinusoid, ramp, and bias functions appearing in components of a platform‐to‐platform relative rotation vector. Isolation of any particular drifting gyro within two identical Carousel V platforms is assured by an approximately orthogonal alignment of the cluster rotational axes. Gyro drift isolation between two platforms requires neither a hardware difference in platforms nor the application of redundant sensors within any individual pla

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01703.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractCelestial navigationis still in wide use, as indicated by sales of the Nautical and Air Almanacs. One of the questions that has intrigued celestial navigators has been the identification of the most probable position when more than two lines of position are available but do not have a common intersection. If the total spread of azimuth is less than 180° and the error of each line of position is assumed to be equal in magnitude and of the same sign, positive or negative, the fix isexternalto the triangle, in contrast to the usualinternalfix determined by assuming minimum error equal in magnitude alone. An analysis of 100 fixes from observations made from known positions by candidates for the N rating of the U. S. Power Squadrons indicates a definite superiority of the internal fix

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01704.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractAflightto the moon and return requires an array of unique aerospace charts. The USAF Aeronautical Chart and Information Center has supported the charting requirements of NASA's Manned Space Program commencing with the first Mercury flight, followed by Gemini and finally the Apollo mission of landing astronauts on the moon. The various charts used for liftoff, earth orbit, lunar orbit, lunar landing, lunar departure and earth recovery are discussed.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01705.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

AbstractKalman filteringhas been used in a wide variety of aided inertial navigation systems in recent years. Yet it appears that Kalman filtering and its overall role in the integrated system is still not well understood by many in the navigation community. This paper is largely tutorial and is directed toward pinpointing the precise role that the filter plays in the integrated system. The presentation is made from a systems viewpoint with the details of Kalman filtering completely surpressed.It is first noted that in the current generation of aided inertial systems the filter operates only on the system errors and not on total dynamical quantities such as position and velocity. The inertial system is then corrected in accordance with the filter's best estimates of the system errors. It is shown that this mode of operation fits within the framework of complementary filtering which has been used in a number of instrumentation applications. This perspective is particularly useful in helping one understand the system limitations in this mode of operation.Next, it is pointed out that the more general problem of estimating total position and velocity is actually one of nonlinear estimation. Within this context, then, the current scheme of system integration can be seen as a special form of nonlinear filtering known as an extended Kalman filter. When viewed this way, one thinks of the inertial system as providing the estimated trajectory, and the aiding sources are the noisy measurements that provide corrections to the trajectory. This viewpoint gives some additional insight into the filter limitations, because nonlinear estimation theory can be brought to bear on the problem.In summary, the current state of the art is on a plateau in terms of system organization, and has been for the past decade. No genuinely new information‐processing concepts have been introduced into the navigation business since the early Sixties. The paper concludes on a speculative note with regard to possible advances in system organizatio

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01706.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY

摘要:

Abstractthe paper describesthe principal characteristics of SECANT, a system for the Separation and Control of Aircraft using Non‐synchronous Techniques. This cooperative, transponding collision‐avoidance system, designed to be compatible within the entire aviation community, is capable of accommodating the dense air traffic anticipated for the 1980s and beyond. It makes available to the pilot evasion or escape maneuvers in any direction—vertical, horizontal, or a combination.SECANT helps the pilot to avoid mid‐air collisions by transmitting probes and receiving replies with a 1 μs pulse up to 1000 pulses/s on 24 different frequencies. Various discriminants are used to eliminate undesired signals, and the false alarm rate is near zero.The capabilities of each of the following modular equipments are discussed: Remitter, Proximity Warning Indicator, Vertical Escape Collision Avoidance System, Vicinity Traffic Finder, Collision‐Avoidance System, and Traffic‐Monitoring System. The correlator, which transmits a randomly selected frequency probe and, when a corresponding frequency probe is received, retransmits an appropriate reply, is described. The theory of operation is presented, and development plans

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1972.tb01707.x

出版商:Blackwell Publishing Ltd    

年代:1972

数据来源: WILEY