Engineering topics

Szatkowski, G. P.

Publications and source records attributed to Szatkowski, G. P..

6 records

NASA NTRS1991

Expert system decision support for low-cost launch vehicle operations

Progress in assessing the feasibility, benefits, and risks associated with AI expert systems applied to low cost expendable launch vehicle systems is described. Part one identified potential application areas in vehicle operations and on-board functions, assessed measures of cost benefit, and identified key technologies to aid in the implementation of decision support systems in this environment. Part two of the program began the development of prototypes to demonstrate real-time vehicle checkout with controller and diagnostic/analysis intelligent systems and to gather true measures of cost savings vs. conventional software, verification and validation requirements, and maintainability improvement. The main objective of the expert advanced development projects was to provide a robust intelligent system for control/analysis that must be performed within a specified real-time window in order to meet the demands of the given application. The efforts to develop the two prototypes are described. Prime emphasis was on a controller expert system to show real-time performance in a cryogenic propellant loading application and safety validation implementation of this system experimentally, using commercial-off-the-shelf software tools and object oriented programming techniques. This smart ground support equipment prototype is based in C with imbedded expert system rules written in the CLIPS protocol. The relational database, ORACLE, provides non-real-time data support. The second demonstration develops the vehicle/ground intelligent automation concept, from phase one, to show cooperation between multiple expert systems. This automated test conductor (ATC) prototype utilizes a knowledge-bus approach for intelligent information processing by use of virtual sensors and blackboards to solve complex problems. It incorporates distributed processing of real-time data and object-oriented techniques for command, configuration control, and auto-code generation.

Szatkowski, G. P.↗

NASA NTRS1990

Knowledge base rule partitioning design for CLIPS

This describes a knowledge base (KB) partitioning approach to solve the problem of real-time performance using the CLIPS AI shell when containing large numbers of rules and facts. This work is funded under the joint USAF/NASA Advanced Launch System (ALS) Program as applied research in expert systems to perform vehicle checkout for real-time controller and diagnostic monitoring tasks. The Expert System advanced development project (ADP-2302) main objective is to provide robust systems responding to new data frames of 0.1 to 1.0 second intervals. The intelligent system control must be performed within the specified real-time window, in order to meet the demands of the given application. Partitioning the KB reduces the complexity of the inferencing Rete net at any given time. This reduced complexity improves performance but without undo impacts during load and unload cycles. The second objective is to produce highly reliable intelligent systems. This requires simple and automated approaches to the KB verification & validation task. Partitioning the KB reduces rule interaction complexity overall. Reduced interaction simplifies the V&V testing necessary by focusing attention only on individual areas of interest. Many systems require a robustness that involves a large number of rules, most of which are mutually exclusive under different phases or conditions. The ideal solution is to control the knowledge base by loading rules that directly apply for that condition, while stripping out all rules and facts that are not used during that cycle. The practical approach is to cluster rules and facts into associated 'blocks'. A simple approach has been designed to control the addition and deletion of 'blocks' of rules and facts, while allowing real-time operations to run freely. Timing tests for real-time performance for specific machines under R/T operating systems have not been completed but are planned as part of the analysis process to validate the design.

Mainardi, Joseph D.↗

NASA NTRS1983

Graphics enhanced computer emulation for improved timing-race and fault tolerance control system analysis

A computer simulation system has been developed for the Space Shuttle's advanced Centaur liquid fuel booster rocket, in order to conduct systems safety verification and flight operations training. This simulation utility is designed to analyze functional system behavior by integrating control avionics with mechanical and fluid elements, and is able to emulate any system operation, from simple relay logic to complex VLSI components, with wire-by-wire detail. A novel graphics data entry system offers a pseudo-wire wrap data base that can be easily updated. Visual subsystem operations can be selected and displayed in color on a six-monitor graphics processor. System timing and fault verification analyses are conducted by injecting component fault modes and min/max timing delays, and then observing system operation through a red line monitor.

Szatkowski, G. P.↗

NASA NTRS1982

Real-time microcomputer simulation for space Shuttle/Centaur avionics

The design of a simulator system for emulating the characteristics of Shuttle/Centaur avionic support equipment for launching the Solar Polar Mission and the Galileo probe are discussed. The simulators are being constructed on a modular basis for the Centaur control avionics, the Centaur Airborne Support Equipment avionics, the tanking skid ground support equipment, development mechanisms, the tanking skid ground support equipment, deployment mechanisms, the tanking onboard fluid functions, the star scanner guidance update avionics, the Orbiter command interface avionics, and the Orbiter power system. Each simulator portrays the actual working conditions, including signal delay times and harnessing. Block diagrams are provided of the interfaces and a flow diagram is presented of the software.

Szatkowski, G. P.↗

NASA NTRS1981

Design and verification of a multiple fault tolerant control system for STS applications using computer simulation

General Dynamics/Convair is under NASA contract to integrate the Centaur upper stage into the space transportation system for future planetary missions. This requires that control of all safety critical functions be two-failure tolerant. The control system developed consists of five asynchronous computers, each contributing at their outputs to a 3-out-of-5 voting plane. Subsystem control is based on an end function redundancy management scheme. Analysis of multiple component failures and worst-case time-phase asynchrony among the computers is performed by a real-time computer simulation. The simulation emulates the hardware and subsystem interfaces, wire by wire, providing assessibility to any component for the insertion of preprogrammed failures. Observability is provided via a graphics system and diagnostic software. The simulation provides an engineering tool where the integrity of control system hardware and imbedded software can be demonstrated.

Szatkowski, G. P.↗

NASA NTRS1981

Real-time computer simulation/emulation for verification of multi-fault-tolerant control of Centaur-in-Shuttle

NASA has contracted with General Dynamics to design and develop an advanced Centaur liquid upper stage for support of the Galileo and Solar Polar interplanetary missions in 1985-86. The control of the Centaur while it resides in the Shuttle cargo bay must meet the STS safety requirements to be dual failure tolerant in all mission critical functions. The demonstration of the integrity of this control system in the event of multiple component failures and worst-case time-phase asynchroniety among the system's computers is performed by a real-time computer simulation. The simulation emulates the control hardware, subsystem interfaces, and imbedded software processes, wire-by-wire, to provide accessibility for fault insertion. Observability is provided via graphics and diagnostic software. Verification is the product of Monte Carlo simulation analysis.

Szatkowski, G. P.↗