Showing papers on "System integration published in 1972"

Integrated Navigation Systems and Kalman Filtering: A Perspective

Abstract: Kalman filtering has 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 organization

Communication mechanism for data transfer and control between data processing systems and subsystems

Abstract: Apparatus for establishing and maintaining communication between a number of different types of subsystems of a data processing system. The apparatus contains elements which are subsettable with respect to the various functions which are performed depending upon the characteristics of each of the subsystems which are connected together.

A Model-Following Variable Stability System for the NASA ARC X-14B

Abstract: A description is presented of the basic design concept, hardware design, ground and inflight acceptance testing of a Variable Stability System (VSS) installed on the NASA ARC X-14B, a twin-engine, single-seated VTOL airplane. The variable stability system was of the model-following type and provided variability in the three rotational degrees of freedom. A general-purpose airborne digital computer was used as the model residence and was an integral part of the hybrid model-following flight control system. The initial system design was achieved using optimal control techniques and the ASP computer program. Single-degree-of-freedom simulations were used to introduce nonlinear characteristics to the synthesis process, and these were extended to a sixdegree-of-freedom simulation for final system synthesis and analysis. The digital computer software acceptance testing involved emulation of the system on the IBM 360 and extensive bench tests of the computer and data adaptor combination. Systems integration and acceptance testing was initiated in a ground test mode which was then extended to testing on a captive rig and culminated in flight acceptance testing in the hover flight mode. It is demonstrated that the system was capable of model-following to the NASA specifications. The major advantages of the digital computer were the reprogramming capability, reliability of operation, and the light weight and low volume of the installation which were critical in this application. The digital computer hardware and software performance was extremely satisfactory in the hybrid flight control operation, while the analog portion of the system took considerable time for alignment and adjustment.

Solar Electric Propulsion System Integration Technology (SEPSIT). Volume 1: Technical summary

Abstract: The use of solar electric propulsion as a means of exploring space beyond the reach of ballistic missions was investigated. The method used was to study the application of this new propulsion technology to a future flight project. A 1980 Encke rendezvous mission was chosen because a design successful for Encke could be used for less difficult, but scientifically rewarding, missions. Design points for the mission and for the thrust subsystem were specified. The baseline-vehicle design was defined. A preliminary functional description document for the thrust subsystem was originated. Analyses were performed in support of the design point selection for the SEP-module thrust subsystem to specify parameters, to clarify and optimize the interface requirements, and to assure feasibility of some of the more critical technological aspects of SEP application.

Overview of Some Problems in Ground Transportation

Abstract: SOME PROBLEM AREAS IN GROUND TRANSPORTATION SYSTEMS, ALONG WITH AEROSPACE SKILL APPLICATIONS ARE SURVEYED. SOME TECHNOLOGY AREAS ARE DISCUSSED: PERFORMANCE IN THE CONTEXT OF BLOCK SPEED RELATING TO STATION SPACING AND PASSENGER COMFORT, SYSTEM CAPACITY RELATING TO VEHICLE SIZE AND HEADWAY, AND POWER REQUIREMENTS AS IMPACTED BY VEHICLE- GUIDEWAY INTERACTION; SUSPENSION DYNAMICS IN THE CONTEXT OF RIDE QUALITY AND THE TRADE BETWEEN GUIDEWAY ROUGHNESS AND SUSPENSION SOPHISTICATION; PROPULSION AND POWER IN THE CONTEXT OF ELECTRIC SYSTEMS FOR MINIMUM ON-LINE NOISE AND POLLUTION; GUIDEWAYS IN THE CONTEXT OF SYSTEM COST SENSITIVITY TO CONFIGURATION AND STIFFNESS REQUIREMENTS AND INTERACTION WITH OTHER SYSTEM ELEMENTS; AND CONTROL AND COMMUNICATIONS IN THE CONTEXT OF HIGH CAPACITY, FAIL SAFE TRAFFIC CONTROL. IT IS CONCLUDED THAT NEW SYSTEM DEVELOPMENT, SYSTEMS INTEGRATION AND MANY TECHNOLOGY AREAS CAN BENEFIT FROM APPLICATION OF BASIC AEROSPACE SKILLS, BUT THAT OTHER AREAS SUCH AS SOCIOPOLITICAL INSTITUTIONAL CONSTRAINTS REQUIRE CONSIDERABLE AEROSPACE ACCLIMATION. /AUTHOR/