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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 NTRS2002

Noise screen for attitude control system

An attitude control system comprising a controller and a noise screen device coupled to the controller. The controller is adapted to control an attitude of a vehicle carrying an actuator system that is adapted to pulse in metered bursts in order to generate a control torque to control the attitude of the vehicle in response to a control pulse. The noise screen device is adapted to generate a noise screen signal in response to the control pulse that is generated when an input attitude error signal exceeds a predetermined deadband attitude level. The noise screen signal comprises a decaying offset signal that when combined with the attitude error input signal results in a net attitude error input signal away from the predetermined deadband level to reduce further control pulse generation.

Rodden, John J.↗
DOE OSTI2015

Online remote control systems for static and dynamic compression and decompression using diamond anvil cells

The ability to remotely control pressure in diamond anvil cells (DACs) in accurate and consistent manner at room temperature, and at cryogenic and elevated temperatures, is crucial for effective and reliable operation of a high-pressure synchrotron facility such as High Pressure Collaborative Access Team (HPCAT). Over the last several years, a considerable effort has been made to develop instrumentation for remote and automated pressure control in DACs during synchrotron experiments. We have designed and implemented an array of modular pneumatic (double-diaphragm), mechanical (gearboxes), and piezoelectric devices and their combinations for controlling pressure and compression/decompression rate at various temperature conditions from 4 K in cryostats to several thousand Kelvin in laser-heated DACs. Because HPCAT is a user facility and diamond cells for user experiments are typically provided by users, our development effort has been focused on creating different loading mechanisms and frames for a variety of existing and commonly used diamond cells rather than designing specialized or dedicated diamond cells with various drives. In this paper, we review the available instrumentation for remote static and dynamic pressure control in DACs and show some examples of their applications to high pressure research.

47 OTHER INSTRUMENTATION↗
NASA NTRS1994

An Object-Oriented Graphical User Interface for a Reusable Rocket Engine Intelligent Control System

An intelligent control system for reusable rocket engines under development at NASA Lewis Research Center requires a graphical user interface to allow observation of the closed-loop system in operation. The simulation testbed consists of a real-time engine simulation computer, a controls computer, and several auxiliary computers for diagnostics and coordination. The system is set up so that the simulation computer could be replaced by the real engine and the change would be transparent to the control system. Because of the hard real-time requirement of the control computer, putting a graphical user interface on it was not an option. Thus, a separate computer used strictly for the graphical user interface was warranted. An object-oriented LISP-based graphical user interface has been developed on a Texas Instruments Explorer 2+ to indicate the condition of the engine to the observer through plots, animation, interactive graphics, and text.

Litt, Jonathan S.↗
NASA NTRS1976

Mechanization of and experience with a triplex fly-by-wire backup control system

A redundant three axis analog control system was designed and developed to back up a digital fly by wire control system for an F-8C airplane. The mechanization and operational experience with the backup control system, the problems involved in synchronizing it with the primary system, and the reliability of the system are discussed. The backup control system was dissimilar to the primary system, and it provided satisfactory handling through the flight envelope evaluated. Limited flight tests of a variety of control tasks showed that control was also satisfactory when the backup control system was controlled by a minimum displacement (force) side stick. The operational reliability of the F-8 digital fly by wire control system was satisfactory, with no unintentional downmodes to the backup control system in flight. The ground and flight reliability of the system's components is discussed.

Lock, W. P.↗
DOE OSTI2012

Cyber Security Testing and Training Programs for Industrial Control Systems

Service providers rely on industrial control systems (ICS) to manage the flow of water at dams, open breakers on power grids, control ventilation and cooling in nuclear power plants, and more. In today's interconnected environment, this can present a serious cyber security challenge. To combat this growing challenge, government, private industry, and academia are working together to reduce cyber risks. The Idaho National Laboratory (INL) is a key contributor to the Department of Energy National SCADA Test Bed (NSTB) and the Department of Homeland Security (DHS) Control Systems Security Program (CSSP), both of which focus on improving the overall security posture of ICS in the national critical infrastructure. In support of the NSTB, INL hosts a dedicated SCADA testing facility which consists of multiple control systems supplied by leading national and international manufacturers. Within the test bed, INL researchers systematically examine control system components and work to identify vulnerabilities. In support of the CSSP, INL develops and conducts training courses which are designed to increase awareness and defensive capabilities for IT/Control System professionals. These trainings vary from web-based cyber security trainings for control systems engineers to more advanced hands-on training that culminates with a Red Team/ Blue Team exercise that is conducted within an actual control systems environment. INL also provides staffing and operational support to the DHS Industrial Control Systems Cyber Emergency Response Team (ICS-CERT) Security Operations Center which responds to and analyzes control systems cyber incidents across the 18 US critical infrastructure sectors.

13 HYDRO ENERGY↗
NASA NTRS2018

Developing a Foundation for Space-Based Two-Phase Thermal Control Systems: Future of 2-Phase Thermal Control

Two-phase thermal control systems in microgravity, with significant density differences between phases, pose challenges for many current and proposed spacecraft systems. Because of the lack of understanding of these effects and the inability to scale multiphase systems in low gravity, NASA generally opts to avoid using two-phase systems for spacecraft despite the significant performance increases and lower mass. The goal of this panel discussion will be to identify key technology gaps and challenges that thermal engineers face today when considering a two-phase thermal management system. The panel discussion will begin with a brief overview of recent and on-going NASA projects designed to elicit a fundamental understanding of gas-liquid two phase behavior as it applies to thermal control systems in the Space environment. The projects/experiments discussed will range from boiling/condensation fundamentals, heat pipes, and cryogenic storage systems. We will identify what fundamental question or questions are being addressed in each case. An overview will be also be presented to address future mission needs and the specific advantages multi-phase systems offer, in particular for low cost planetary science missions and enabling missions in extreme environments. The need for efficient heat transfer with concurrent spatial and temporal temperature stability to reduce thermally-induced noise drives a serious look at multi-phase systems as a solution. Furthermore, missions to environments such as the Venus surface or penetration of ice layers in ocean worlds will likely require them. Time will be allocated at the end of this session to allow comments and questions from attendees. The intent is to use this session as a starting point to advocate for a coordinated technology development effort in this area.

Thermal Control Systems↗
DOE OSTI2019

Bang-Bang Theorem for a Coupled ODE-PDE Control System

An optimal control problem for a system of one dimensional hyperbolic conservation laws is considered. The system is controlled through the boundary condition, which depends on the state of a nonlinear control system. It is proven that the problem has an optimal solution; moreover, it admits ε-optimal solutions generated by bang-bang controls. Bibliography: 8 titles. Illustrations: 1 figure.

97 MATHEMATICS AND COMPUTING↗
NASA NTRS1957

Experimental Investigation of Temperature Feedback Control Systems Applicable to Turbojet-engine Control

Temperature - fuel-flow and temperature-area feedback control systems were investigated as means of controlling tailpipe gas temperature of a turbojet engine during transient operation in the high-speed region. Proportional-plus-integral control was used in both systems, but in the temperature-area control system it was necessary to add nonlinear components to the basic proportional-plus-integral control to provide satisfactory transient response to a desired step increase in temperature. Time integral of temperature-error functions were used as criteria for determining optimum transient response. A description of engine dynamics was obtained from frequency-response data.

ENGINES, TURBOJET↗
DOE OSTI2024

An Update on Microreactor Automated Control System (MACS)

Automation of control systems is expected to be important in the economic and safe operation of microreactors. There is a need to develop and demonstrate automated control for microreactors, along with the development of testbeds for this purpose. This report provides updates on the status of a microreactor automated control system (MACS) testbed developed to test control system automation. While a future goal is to demonstrate this system using a prototypic microreactor such as MARVEL, the present focus is on developing and testing within a non-nuclear testbed. The testbed, developed in collaboration with Idaho National Laboratory, includes hardware-in-the-loop simulation and uses a Modelica-based model of a prototypic microreactor for use in testing control automation. Research to date at Oak Ridge National Laboratory has focused on the development of prototypic software for automating plant-level control under selected scenarios. Empirical testing on the integrated MACS testbed was performed to quantify key characteristics of the integrated testbed and to demonstrate the use of the software for automating the calculation and use of actuation setpoints for selected load-following scenarios. Ongoing research is focused on integrating additional control algorithms that utilize data from newly included sensors within the MACS hardware testbed, as well as demonstrating and assessing the performance of the different automated control algorithms on multiple additional operational scenarios.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
NASA NTRS1973

Floating-point system quantization errors in digital control systems

The results are reported of research into the effects on system operation of signal quantization in a digital control system. The investigation considered digital controllers (filters) operating in floating-point arithmetic in either open-loop or closed-loop systems. An error analysis technique is developed, and is implemented by a digital computer program that is based on a digital simulation of the system. As an output the program gives the programing form required for minimum system quantization errors (either maximum of rms errors), and the maximum and rms errors that appear in the system output for a given bit configuration. The program can be integrated into existing digital simulations of a system.

Phillips, C. L.↗
NASA NTRS2000

Process Upsets Involving Trace Contaminant Control Systems

Paradoxically, trace contaminant control systems that suffer unexpected upsets and malfunctions can release hazardous gaseous contaminants into a spacecraft cabin atmosphere causing potentially serious toxicological problems. Trace contaminant control systems designed for spaceflight typically employ a combination of adsorption beds and catalytic oxidation reactors to remove organic and inorganic trace contaminants from the cabin atmosphere. Interestingly, the same design features and attributes which make these systems so effective for purifying a spacecraft's atmosphere can also make them susceptible to system upsets. Cabin conditions can be contributing causes of phenomena such as adsorbent "rollover" and catalyst poisoning can alter a systems performance and in some in stances release contamination into the cabin. Evidence of these phenomena has been observed both in flight and during ground-based tests. The following discussion describes specific instances of system upsets found in trace contaminant control systems, groups these specific upsets into general hazard classifications, and recommends ways to minimize these hazards.

Graf, John C.↗
DOE OSTI2014

A Runtime Verification Framework for Control System Simulation

n a standard workflow for the validation of a control system, the control system is implemented as an extension to a simulator. Such simulators are complex software systems, and engineers may unknowingly violate constraints a simulator places on extensions. As such, errors may be introduced in the implementation of either the control system or the simulator leading to invalid simulation results. This paper presents a novel runtime verification approach for verifying control system implementations within simulators. The major contribution of the approach is the two-tier specification process. In the first tier, engineers model constraints using a domain-specific language tailored to modeling a controller’s response to changes in its input. The language is high-level and effectively hides the implementation details of the simulator, allowing engineers to specify design-level constraints independent of low-level simulator interfaces. In the second tier, simulator developers provide mapping rules for mapping design-level constraints to the implementation of the simulator. Using the rules, an automated tool transforms the design-level specifications into simulator-specific runtime verification specifications and generates monitoring code which is injected into the implementation of the simulator. During simulation, these monitors observe the input and output variables of the control system and report changes to the verifier. The verifier checks whether these changes follow the constraints of the control system. We describe application of this approach to the verification of the constraints of an HVAC control system implemented with the power grid simulator GridLAB-D.

control system↗
NASA NTRS1981

Velocity vector control system augmented with direct lift control

A pilot-controlled stability control system that employs direct lift control (spoiler control) with elevator control to control the flight path angle of an aircraft is described. A computer on the aircraft generates an elevator control signal and a spoiler control signal, using a pilot-controlled pitch control signal and pitch rate, vertical velocity, roll angle, groundspeed, engine pressure ratio and vertical acceleration signals which are generated on the aircraft. The direct lift control by the aircraft spoilers improves the response of the aircraft flight path angle and provides short term flight path stabilization against environmental disturbances.

Tisdale, H. F., Sr.↗
NASA NTRS1973

Analysis and design of a capsule landing system and surface vehicle control system for Mars exploration

Problems related to the design and control of a mobile planetary vehicle to implement a systematic plan for the exploration of Mars are reported. Problem areas include: vehicle configuration, control, dynamics, systems and propulsion; systems analysis, terrain modeling and path selection; and chemical analysis of specimens. These tasks are summarized: vehicle model design, mathematical model of vehicle dynamics, experimental vehicle dynamics, obstacle negotiation, electrochemical controls, remote control, collapsibility and deployment, construction of a wheel tester, wheel analysis, payload design, system design optimization, effect of design assumptions, accessory optimal design, on-board computer subsystem, laser range measurement, discrete obstacle detection, obstacle detection systems, terrain modeling, path selection system simulation and evaluation, gas chromatograph/mass spectrometer system concepts, and chromatograph model evaluation and improvement.

Frederick, D. K.↗
NASA NTRS1973

Optimality of incompletely measurable active and passive attitude control systems

Passive attitude control systems and active systems with incomplete state measurements are only suboptimal systems in the sense of optimal control theory, since optimal systems require complete state measurements or state estimations. An optimal system, then, requires additional hardware (especially in the case of flexible spacecraft) which results in higher costs. Therefore, it is a real engineering problem to determine how much an optimal system exceeds the suboptimal system, or in other words, what is the suboptimal system's degree of optimality. The problem will be treated in three steps: (1) definition of the degree of optimality for linear, time-invariant systems; (2) a computation method using the quadratic cost functional; (3) application to a gravity-gradient stabilized three-body satellite and a spinning flexible satellite.

Schiehlen, W.↗
DOE OSTI2022

Battery energy storage control systems and methods for a grid tie inverter coupled to a photovoltaic system

A distributed control system uses a central controller in Internet communication with a local controller to manage grid tie attachment with a battery to form an integrated battery energy storage system (BESS). The BESS is capable of charging or discharging the battery, as well as correcting grid phase with volt amp reactive (VAR) leading or lagging operation modes. Examples shown include simple BESS charging and discharging, BESS integrated with renewable energy sources (here photovoltaic), and direct current fast charge (DCFC) connections with an electric vehicle.

Gadh, Rajit↗