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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 217 records · Page 12
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

A new approach to telemetry data processing

An approach for a preprocessing system for telemetry data processing was developed. The philosophy of the approach is the development of a preprocessing system to interface with the main processor and relieve it of the burden of stripping information from a telemetry data stream. To accomplish this task, a telemetry preprocessing language was developed. Also, a hardware device for implementing the operation of this language was designed using a cellular logic module concept. In the development of the hardware device and the cellular logic module, a distributed form of control was implemented. This is accomplished by a technique of one-to-one intermodule communications and a set of privileged communication operations. By transferring this control state from module to module, the control function is dispersed through the system. A compiler for translating the preprocessing language statements into an operations table for the hardware device was also developed. Finally, to complete the system design and verify it, a simulator for the collular logic module was written using the APL/360 system.

Broglio, C. J.↗
NASA NTRS1975

Testability enhancement in digital system design

A new way of employing hardware redundancy to reduce the number of tests for fault detection in both combinational and synchronous sequential circuits is investigated. An approach is presented for utilizing systematic redundancy to simplify design work. Models for PLM (programmable logic module) and CMM (controllable memory module) are depicted. Systematic design and detection procedures are described. Using these procedures, an easily testable circuit (for stuck faults) can be designed. In contrast to the earlier results on fault detection in logic circuit, two tests are needed to detect any stuck faults of combinational logic circuit. Four tests are necessary and sufficient to detect any stuck faults of elementary logic gates and the malfunction of flip-flops of synchronous sequential circuit using Delay flip-flops or trigger flip-flops.

Chuang, C. S.↗
NASA NTRS1971

Minimal logic block encoder Patent

Encoders designed to generate comma free biorthogonal Reed-Muller type code comprising conversion of 64 6-bit words into 64 32-bit data for communication purposes

Duffy, J. O.↗
NASA NTRS1988

New mode switching algorithm for the JPL 70-meter antenna servo controller

The design of control mode switching algorithms and logic for JPL's 70 m antenna servo controller are described. The old control mode switching logic was reviewed and perturbation problems were identified. Design approaches for mode switching are presented and the final design is described. Simulations used to compare old and new mode switching algorithms and logic show that the new mode switching techniques will significantly reduce perturbation problems.

Nickerson, J. A.↗
NASA NTRS1998

An Object-Oriented Interface to the CCSDS Ground Telecommand Services

The Telecommand Data Routing and Channel Services defined by the Consultative Committee for Space Data Systems (CCSDS) are flexible enough to support a myriad of commanding models. Because the standard is so broad, the traditional approach has been to implement only the portion of the standard needed by the particular spacecraft being tested/operated. Tasked with providing Telecommand Services for an entire class of spacecraft, where each spacecraft may choose any valid CCSDS commanding model, NASA Code 584 designed a common architecture capable of handling the full CCSDS protocol. The solution uses another CCSDS standard - the Standard Formatted Data Unit (SFDU) as the interface to the Telecommand Services. SFDUs provide a consistent way of labelling data objects, as well as allowing data objects to encapsulate other data objects. The resulting interface is: - Flexible: The full Data Routing and Channel Services are available via a single interface. The client (i.e. the command source) may enter commands at any layer within the protocol stack, specify any of the data aggregation or segmentation methods, and dynamically set any configuration parameter defined in the standard. - Object-oriented: Each object specifies both the data and the actions to be performed with the data. An object may contain other objects. - Expandable: New capabilities are added by defining new objects. Objects pass thru the protocol layers until they reach the applicable layer. The resulting design is: - Modular: The logic for each protocol layer is contained in a separate Application Program Interface (API). The objects used for the external interface are also used for communication between layers. - Distributable: The design can be split along any layer boundary for distribution across multiple machines. The objects ensure data consistency across platforms. This paper describes the SFDU-based interface and the resulting protocol implementation. The implementation is currently used by NASA (National Aeronautics and Space Administration) for integration & test of the microwave Anisotropy Probe (MAP) and Earth observer-I (EO-l) spacecraft. It will be used for post-launch operations of these spacecraft as well as the Imager for Magnetopause to Aurora Global Exploration (IMAGE) spacecraft.

Ray, Timothy Joseph↗
NASA NTRS1978

Design representation and consistency maintenance needs

Two major issues of data base support for large-scale engineering design are considered. The first deals with the need to support multidisciplinary, hierarchical and interactive design without imposing a priori constraints on the sequence of design decisions. An abstract logical model of the data base capable of such support is outlined. The second issue deals with the role the data base must play in maintaining integrity and consistency among the data representing the emerging design. A tentative model implementing a number of consistency management functions is presented.

Eastman, C. M.↗
NASA NTRS1989

Hybrid Propulsion Technology Program, phase 1. Volume 1: Executive summary

The study program was contracted to evaluate concepts of hybrid propulsion, select the most optimum, and prepare a conceptual design package. Further, this study required preparation of a technology definition package to identify hybrid propulsion enabling technologies and planning to acquire that technology in Phase 2 and demonstrate that technology in Phase 3. Researchers evaluated two design philosophies for Hybrid Rocket Booster (HRB) selection. The first is an ASRM modified hybrid wherein as many components/designs as possible were used from the present Advanced Solid Rocket Motor (ASRM) design. The second was an entirely new hybrid optimized booster using ASRM criteria as a point of departure, i.e., diameter, thrust time curve, launch facilities, and external tank attach points. Researchers selected the new design based on the logic of optimizing a hybrid booster to provide NASA with a next generation vehicle in lieu of an interim advancement over the ASRM. The enabling technologies for hybrid propulsion are applicable to either and vehicle design may be selected at a downstream point (Phase 3) at NASA's discretion. The completion of these studies resulted in ranking the various concepts of boosters from the RSRM to a turbopump fed (TF) hybrid. The scoring resulting from the Figure of Merit (FOM) scoring system clearly shows a natural growth path where the turbopump fed solid liquid staged combustion hybrid provides maximized payload and the highest safety, reliability, and low life cycle costing.

Source record↗
NASA NTRS2002

The Design of Fault Tolerant Quantum Dot Cellular Automata Based Logic

As transistor geometries are reduced, quantum effects begin to dominate device performance. At some point, transistors cease to have the properties that make them useful computational components. New computing elements must be developed in order to keep pace with Moore s Law. Quantum dot cellular automata (QCA) represent an alternative paradigm to transistor-based logic. QCA architectures that are robust to manufacturing tolerances and defects must be developed. We are developing software that allows the exploration of fault tolerant QCA gate architectures by automating the specification, simulation, analysis and documentation processes.

Armstrong, C. Duane↗
NASA NTRS2005

Multi-Mission System Architecture Platform: Design and Verification of the Remote Engineering Unit

The Multi-Mission System Architecture Platform (MSAP) represents an effort to bolster efficiency in the spacecraft design process. By incorporating essential spacecraft functionality into a modular, expandable system, the MSAP provides a foundation on which future spacecraft missions can be developed. Once completed, the MSAP will provide support for missions with varying objectives, while maintaining a level of standardization that will minimize redesign of general system components. One subsystem of the MSAP, the Remote Engineering Unit (REU), functions by gathering engineering telemetry from strategic points on the spacecraft and providing these measurements to the spacecraft's Command and Data Handling (C&DH) subsystem. Before the MSAP Project reaches completion, all hardware, including the REU, must be verified. However, the speed and complexity of the REU circuitry rules out the possibility of physical prototyping. Instead, the MSAP hardware is designed and verified using the Verilog Hardware Definition Language (HDL). An increasingly popular means of digital design, HDL programming provides a level of abstraction, which allows the designer to focus on functionality while logic synthesis tools take care of gate-level design and optimization. As verification of the REU proceeds, errors are quickly remedied, preventing costly changes during hardware validation. After undergoing the careful, iterative processes of verification and validation, the REU and MSAP will prove their readiness for use in a multitude of spacecraft missions.

Sartori, John↗
NASA NTRS1974

Digital adaptive flight controller development

A design study of adaptive control logic suitable for implementation in modern airborne digital flight computers was conducted. Two designs are described for an example aircraft. Each of these designs uses a weighted least squares procedure to identify parameters defining the dynamics of the aircraft. The two designs differ in the way in which control law parameters are determined. One uses the solution of an optimal linear regulator problem to determine these parameters while the other uses a procedure called single stage optimization. Extensive simulation results and analysis leading to the designs are presented.

Kaufman, H.↗
NASA NTRSDate not supplied

Model Predictive Control Strategies for Turbine Electrified Energy Management

The increasing electrification of aircraft propulsion systems is leading to new control architectures being developed to address integration between electric machines and gas-based turbine engines. For hybrid-electric propulsion systems, current conceptual architectures often couple electric machines with the shafts of gas turbine engines and introduce energy storage. Leveraging the electrical power system of hybridized engines, Turbine Electrified Energy Management (TEEM) is a recent control approach that improves transient operability in an effort to enable more efficient and lighter weight turbomachinery. This study seeks to expand TEEM’s application beyond traditional proportional-integral (PI) control by presenting linear model predictive control (MPC) schemes to execute the TEEM concept. Through constraint selection and cost function design, transient operability goals for TEEM are considered with no external logic or saturation. Unique to the designs are the use of a washout filter, which simplifies transient detection and motor activation logic. The proposed architectures are implemented with both centralized MPC and distributed MPC approaches, and comparisons are drawn to a benchmark PI controller simulated on a nonlinear turbofan engine model at one ground condition and one cruise condition. Performance is evaluated using compressor maps, stall margin performance, and two novel metrics: transient stack usage and transient excursion integral. Results reveal the linear MPC scheme performs comparably to the baseline controller and can be implemented in at least two distinct configurations with potential for further modifications, thus establishing the groundwork for future investigations.

Model Predictive Control↗
NASA NTRSDate not supplied

Model Predictive Control Strategies for Turbine Electrified Energy Management

The increasing electrification of aircraft propulsion systems is leading to new control architectures being developed to address integration between electric machines and gas-based turbine engines. For hybrid-electric propulsion systems, current conceptual architectures often couple electric machines with the shafts of gas turbine engines and introduce energy storage. Leveraging the electrical power system of hybridized engines, Turbine Electrified Energy Management (TEEM) is a recent control approach that improves transient operability in an effort to enable more efficient and lighter weight turbomachinery. This study seeks to expand TEEM’s application beyond traditional proportional integral (PI) control by presenting linear model predictive control (MPC) schemes to execute the TEEM concept. Through constraint selection and cost function design, transient operability goals for TEEM are considered with no external logic or saturation. Unique to the designs are the use of a washout filter, which simplifies transient detection and motor activation logic. The proposed architectures are implemented with both centralized MPC and distributed MPC approaches, and comparisons are drawn to a benchmark PI controller simulated on a nonlinear turbofan engine model at one ground condition and one cruise condition. Performance is evaluated using compressor maps, stall margin performance, and two novel metrics: transient stack usage and transient excursion integral. Results reveal the linear MPC scheme performs comparably to the baseline controller and can be implemented in at least two distinct configurations with potential for further modifications, thus establishing the groundwork for future investigations.

Model Predictive Control↗
NASA NTRS2023

Model Predictive Control Strategies for Turbine Electrified Energy Management

The increasing electrification of aircraft propulsion systems is leading to new control architectures being developed to address integration between electric machines and gas-based turbine engines. For hybrid-electric propulsion systems, current conceptual architectures often couple electric machines with the shafts of gas turbine engines and introduce energy storage. Leveraging the electrical power system of hybridized engines, Turbine Electrified Energy Management (TEEM) is a recent control approach that improves transient operability in an effort to enable more efficient and lighter weight turbomachinery. This study seeks to expand TEEM’s application beyond traditional proportional-integral (PI) control by presenting linear model predictive control (MPC) schemes to execute the TEEM concept. Through constraint selection and cost function design, transient operability goals for TEEM are considered with no external logic or saturation. Unique to the designs are the use of a washout filter, which simplifies transient detection and motor activation logic. The proposed architectures are implemented with both centralized MPC and distributed MPC approaches, and comparisons are drawn to a benchmark PI controller simulated on a nonlinear turbofan engine model at one ground condition and one cruise condition. Performance is evaluated using compressor maps, stall margin performance, and two novel metrics: transient stack usage and transient excursion integral. Results reveal the linear MPC scheme performs comparably to the baseline controller and can be implemented in at least two distinct configurations with potential for further modifications, thus establishing the groundwork for future investigations.

Model Predictive Control↗
NASA NTRS1987

VLSI-Chip Tester

Compact test set integrated in computer-aided design system. Test set performs functional tests on very-large-scale integrated (VLSI) circuits. Makes tests from points within VLSI chip as well as at input and output pins. Used for quality control and design; in latter capacity, checks internal logic functions on chip and feed results directly to computer-aided design system for correction. Also simulates operation of chip design before chip is made. VLSI Tester contains three power supplies, control logic, and standard multibus circuit board in aluminum chassis. Chassis fits under platform of microprobe station. Multibus board links tester to interactive terminals and to host computer.

Deutsch, Leslie J.↗
NASA NTRS1996

Failure-Modes-And-Effects Analysis Of Software Logic

Rigorous analysis applied early in design effort. Method of identifying potential inadequacies and modes and effects of failures caused by inadequacies (failure-modes-and-effects analysis or "FMEA" for short) devised for application to software logic.

Garcia, Danny↗
NASA NTRS1982

Electron lithography STAR design guidelines. Part 3: The mosaic transistor array applied to custom microprocessors. Part 4: Stores logic arrays, SLAs implemented with clocked CMOS

The Mosaic Transistor Array is an extension of the STAR system developed by NASA which has dedicated field cells designed to be specifically used in semicustom microprocessor applications. The Sandia radiation hard bulk CMOS process is utilized in order to satisfy the requirements of space flights. A design philosophy is developed which utilizes the strengths and recognizes the weaknesses of the Sandia process. A style of circuitry is developed which incorporates the low power and high drive capability of CMOS. In addition the density achieved is better than that for classic CMOS, although not as good as for NMOS. The basic logic functions for a data path are designed with compatible interface to the STAR grid system. In this manner either random logic or PLA type structures can be utilized for the control logic.

Trotter, J. D.↗
NASA NTRS1974

Force sharing in high-power parallel servo-actuators

The various existing force sharing schemes were examined by conducting a literature survey. A list of potentially applicable concepts was compiled from this survey, and a brief analysis was then made of each concept, which resulted in two competing schemes being selected for in-depth evaluation. A functional design of the equalization logic for the two schemes was undertaken and specific space shuttle application was chosen for experimental evaluation. The application was scaled down so that existing hardware could be utilized. Next, an analog computer study was conducted to evaluate the more important characteristics of the two competing force sharing schemes. On the basis of the computers study, a final configuration was selected. A load simulator was then designed to evaluate this configuration on actual hardware.

Neal, T. P.↗
NASA NTRS1994

Fuzzy logic application for modeling man-in-the-loop space shuttle proximity operations

A software pilot model for Space Shuttle proximity operations is developed, utilizing fuzzy logic. The model is designed to emulate a human pilot during the terminal phase of a Space Shuttle approach to the Space Station. The model uses the same sensory information available to a human pilot and is based upon existing piloting rules and techniques determined from analysis of human pilot performance. Such a model is needed to generate numerous rendezvous simulations to various Space Station assembly stages for analysis of current NASA procedures and plume impingement loads on the Space Station. The advantages of a fuzzy logic pilot model are demonstrated by comparing its performance with NASA's man-in-the-loop simulations and with a similar model based upon traditional Boolean logic. The fuzzy model is shown to respond well from a number of initial conditions, with results typical of an average human. In addition, the ability to model different individual piloting techniques and new piloting rules is demonstrated.

Brown, Robert B.↗