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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 325 records · Page 18
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Robust eigenstructure assignment by a projection method: Application using multiple optimization criteria

New ideas which lead to feedback control laws for large flexible structures which are insensitive to model uncertainty are presented. A pole placement method is presented which leads to near-unitary closed loop eigenvectors, and a new method is introduced to design the control while simultaneously considering three competing measures of optimality. Robustness versus Integral algorithms are applicable to at least moderately high-dimensioned systems. In the present discussion, controls for two coupled flexible bodies are considered. A 6x24 gain matrix is designed to control a 12 modes system using 6 actuators. Researchers also developed control laws for the R2P2 simulator at Martin Marietta; in this case 3 actuators are used to control a 12th order system. Simulation studies indicate that researchers indeed achieved robust designs without significant difficulties associated with spillover into the uncontrolled modes. Here, several key ideas and numerical results are given. In the references, details of the formulation, discussions of salient features, and connection to the availiable literature are given.

Junkins, J. L.↗
NASA NTRS2000

Technology Development for a Stirling Radioisotope Power System

NASA Glenn Research Center and the Department of Energy are developing a Stirling convertor for an advanced radioisotope power system to provide spacecraft on-board electric power for NASA deep space missions. NASA Glenn is addressing key technology issues through the use of two NASA Phase II SBIRs with Stirling Technology Company (STC) of Kennewick, WA. Under the first SBIR, STC demonstrated a synchronous connection of two thermodynamically independent free-piston Stirling convertors and a 40 to 50 fold reduction in vibrations compared to an unbalanced convertor. The second SBIR is for the development of an Adaptive Vibration Reduction System (AVRS) that will essentially eliminate vibrations over the mission lifetime, even in the unlikely event of a failed convertor. This paper presents the status and results for these two SBIR projects and also discusses a new NASA Glenn in-house project to provide supporting technology for the overall Stirling radioisotope power system development. Tasks for this new effort include convertor performance verification, controls development, heater head structural life assessment, magnet characterization and thermal aging tests, FEA analysis for a lightweight alternator concept, and demonstration of convertor operation under launch and orbit transfer load conditions.

Thieme, Lanny G.↗
NASA NTRS1983

Apparel for Cleaner Clean Rooms

In the 1960s NASA pioneered contamination control technology, providing a base from which aerospace contractors could develop control measures. NASA conducted special courses for clean room technicians and supervisors, and published a series of handbooks with input from various NASA field centers. These handbooks extended aerospace experience to the medical, pharmaceutical, electronics, and other industries where extreme cleanliness is important. American Hospital Supply Company (AHSC) felt that high technology products with increasingly stringent operating requirements in aerospace, electronics, pharmaceuticals and medical equipment manufacturing demanded improvement in contamination control techniques. After studying the NASA handbooks and visiting NASA facilities, the wealth of information gathered resulted in Micro-clean non-woven garments and testing equipment and procedures for evaluating effectiveness.

Source record↗
NASA NTRS2012

Resolving Off-Nominal Situations in Schedule-Based Terminal Area Operations: Results from a Human-in-the-Loop Simulation

A recent human-in-the-loop simulation in the Airspace Operations Laboratory (AOL) at NASA's Ames Research Center investigated the robustness of Controller-Managed Spacing (CMS) operations. CMS refers to AOL-developed controller tools and procedures for enabling arrivals to conduct efficient Optimized Profile Descents with sustained high throughput. The simulation provided a rich data set for examining how a traffic management supervisor and terminal-area controller participants used the CMS tools and coordinated to respond to off-nominal events. This paper proposes quantitative measures for characterizing the participants responses. Case studies of go-around events, replicated during the simulation, provide insights into the strategies employed and the role the CMS tools played in supporting them.

Mercer, Joey↗
NASA NTRS1974

Develop minimum thrustor control laws and select orbits for a geodesy drag-free satellite

The original motivation for studying control laws for pulse plasma systems was based on the improved life characteristics possible with pulse plasma jets. These pulse plasma units are relatively massive compared with cold gas thrustors. As a result, therefore, significant mass savings can be achieved by minimizing the the number of thrustors. The control laws, therefore, were developed for thrust available from two thrustors only. In a spinning satellite, these thrustors are sufficient to completely control the vehicle as long as the spin rate is sufficiently high for a given level of external disturbance. The thrustors are canted so that a component of each is along the plus and minus spin axis. The other component of each thrustor acts in the radial direction. It is sufficient to analyze the behavior in the plane of spin assuming a single thrustor.

Breakwell, J. V.↗
NASA NTRS1983

Large space structures controls research and development at Marshall Space Flight Center: Status and future plans

Work performed in Large Space Structures Controls research and development program at Marshall Space Flight Center is described. Studies to develop a multilevel control approach which supports a modular or building block approach to the buildup of space platforms are discussed. A concept has been developed and tested in three-axis computer simulation utilizing a five-body model of a basic space platform module. Analytical efforts have continued to focus on extension of the basic theory and subsequent application. Consideration is also given to specifications to evaluate several algorithms for controlling the shape of Large Space Structures.

Buchanan, H. J.↗
NASA NTRS1990

A computationally efficient error-based adaptive control scheme for kinematically redundant manipulators

A Cartesian-space control scheme is developed to control the motion of kinematically redundant manipulators with 7 degrees of freedom (DOF). The control scheme consists mainly of proportional-derivative (PD) controllers whose gains are adjusted by an adaptation law driven by the errors between the desired and actual trajectories. The adaptation law is derived using the concept of model reference adaptive control (MRAC) and Liapunov direct method under the assumption that the manipulator performs noncompliant and slowly-varying motions. The developed control scheme is computationally efficient because its implementation does not require the computation of the manipulator dynamics. Computer simulation performed to evaluate the control scheme performance is presented and discussed.

Nguyen, Charles C.↗
NASA NTRS2011

Implementation of CAPIO for Composite Adaptive Control of Cross-Coupled Unstable Aircraft

This paper presents an implementation of a recently developed control allocation algorithm CAPIO (a Control Allocation technique to recover from Pilot Induced Oscillations) for composite adaptive control of an inertially cross coupled unstable aircraft. When actuators are rate-saturated due to either an aggressive pilot command, high gain of the flight control system or some anomaly in the system, the effective delay in the control loop may increase due to the phase shifting between the desired and the achieved system states. This effective time delay may deteriorate the performance or even destabilize the system in some cases, depending on the severity of rate saturation. CAPIO reduces the effective time delay by minimizing the phase shift between the commanded and the actual attitude accelerations. We present simulation results for an unstable aircraft with cross-coupling controlled with a composite adaptive controller in the presence of rate saturation. The simulations demonstrate the potential of CAPIO serving as an effective rate saturation compensator in adverse conditions.

Yildiz, Yildiray↗
NASA NTRS1990

Position control of redundant manipulators using an adaptive error-based control scheme

A Cartesian-space control scheme is developed to control the motion of kinematically redundant manipulators with 7 degrees of freedom (DOF). The control scheme consists mainly of proportional derivative (PD) controllers whose gains are adjusted by an adaptation law driven by the errors between the desired and actual trajectories. The adaptation law is derived using the concept of model reference adaptive control (MRAC) and Lyapunov direct method under the assumption that the manipulator performs non-compliant and slowly-varying motions. The developed control scheme is computationally efficient because its implementation does not require the computation of the manipulator dynamics. Computer simulation performed to evaluate the control scheme performance is presented and discussed.

Nguyen, Charles C.↗
DOE OSTI2024

Dynamic Simulation Modeling and Control of a Desiccant Assisted Direct-expansion Air Handling Unit

Desirable built environments demand simultaneous regulation of thermal comfort and indoor air quality (IAQ) with energy-efficient operation of heating, ventilation and air conditioning (HV AC) systems, which involves controls of temperature, humidity and airborne contaminants simultaneously. This paper presents the efforts of dynamic modeling and initial development control strategy for a desiccant-assisted multi-functional air handling unit (AHU) coupled with a direct-expansion rooftop unit (RTU) system, which aims to achieve multiple functions for indoor environment conditioning with energy efficient control. The RTU-AHU system includes a desiccant wheel for dehumidification and a conceptual direct air capture (DAC) filtering device for CO2 regulation. A Modelica-based dynamic model is developed for this conceptual system, and a simple decentralized control strategy is designed, which combines a differential-enthalpy based AHU return-air ratio control, a demand-controlled ventilation, and supply-air temperature humidity control via the RTU and DW controls. The proposed control method is evaluated with the Modelica simulation model for a selected set of scenarios

Pan, Chao↗
NASA NTRS1985

Programable Multicrate Controller

High-speed, environmentally hardened controller developed for use with commercially available system crates for both experiment control and data handling. Programable crate controller consists of three functional areas: control section utilizes high-speed bit-slice circuitry, memory, and data way interface.

Mook, G. L.↗
NASA NTRS2010

Stability Properties and Cross Coupling Performance of the Control Allocation Scheme CAPIO

This paper presents a stability analysis and an application of a recently developed Control Allocator for recovery from Pilot Induced Oscillations (CAPIO). When actuators are rate-saturated due to either aggressive pilot commands, high gain ight control systems or some anomaly in the system, the effective delay in the control loop may increase. This effective delay increase manifests itself as a phase shift between the commanded and actual system signals and can instigate Pilot induced Oscillations (PIO). CAPIO reduces the e ective time delay by minimizing the phase shift between the commanded and the actual attitude accelerations. We present a stability analysis of CAPIO for a scalar system. In addition, we present simulation results for aircraft with cross-coupling which demonstrates the potential of CAPIO serving as an effective PIO handler in adverse conditions.

Yildiz, Yildiray↗
NASA NTRS1987

Heuristic control of the Utah/MIT dextrous robot hand

Basic hand grips and sensor interactions that a dextrous robot hand will need as part of the operation of an EVA Retriever are analyzed. What is to be done with a dextrous robot hand is examined along with how such a complex machine might be controlled. It was assumed throughout that an anthropomorphic robot hand should perform tasks just as a human would; i.e., the most efficient approach to developing control strategies for the hand would be to model actual hand actions and do the same tasks in the same ways. Therefore, basic hand grips that human hands perform, as well as hand grip action were analyzed. It was also important to examine what is termed sensor fusion. This is the integration of various disparate sensor feedback paths. These feedback paths can be spatially and temporally separated, as well as, of different sensor types. Neural networks are seen as a means of integrating these varied sensor inputs and types. Basic heuristics of hand actions and grips were developed. These heuristics offer promise of control dextrous robot hands in a more natural and efficient way.

Bass, Andrew H., Jr.↗
NASA NTRS1991

Controls for agility research in the NASA High-Alpha Technology Program

The research process being used to develop control law design methodologies and guidelines in the NASA High-Alpha Technology Program are discussed. This step-by-step process consists of four basic elements: (1) control law architecture definition and linear synthesis, (2) nonlinear batch simulation, (3) piloted simulation evaluation, and (4) flight test validation. This paper discusses the research tools being used in this effort and provides a status report on design methodologies and guidelines being developed for each of these elements.

Foster, John V.↗
NASA NTRS1997

A Novel Silicon Micromachined Integrated MCM Thermal Management System

"Micromachining" is a chemical means of etching three-dimensional structures, typically in single- crystalline silicon. These techniques are leading toward what is coming to be referred to as MEMS (Micro Electro Mechanical Systems), where in addition to the ordinary two-dimensional (planar) microelectronics, it is possible to build three-dimensional n-ticromotors, electrically- actuated raicrovalves, hydraulic systems and much more on the same microchip. These techniques become possible because of differential etching rates of various crystallographic planes and materials used for semiconductor n-ticrofabfication. The University of Cincinnati group in collaboration with Karl Baker at NASA Lewis were the first to form micro heat pipes in silicon by the above techniques. Current work now in progress using MEMS technology is now directed towards the development of the next generation in MCM (Multi Chip Module) packaging. Here we propose to develop a complete electronic thermal management system which will allow densifica6on in chip stacking by perhaps two orders of magnitude. Furthermore the proposed technique will allow ordinary conu-nercial integrated chips to be utilized. Basically, the new technique involves etching square holes into a silicon substrate and then inserting and bonding commercially available integrated chips into these holes. For example, over a 100 1/4 in. by 1 /4 in. integrated chips can be placed on a 4 in. by 4 in. silicon substrate to form a Multi-Chip Module (MCM). Placing these MCM's in-line within an integrated rack then allows for three-diniensional stacking. Increased miniaturization of microelectronic circuits will lead to very high local heat fluxes. A high performance thermal management system will be specifically designed to remove the generated energy. More specifically, a compact heat exchanger with milli / microchannels will be developed and tested to remove the heat through the back side of this MCM assembly for moderate and high heat flux applications, respectively. The high heat load application of particular interest in mind is the motor controller developed by Martin Marietta for Nasa to control the thruster's directional actuators on space vechicles. Work is also proposed to develop highly advanced and improved porous wick structures for use in advanced heat loops. The porous wick will be micromachined from silicon using MEMS technology, thus permitting far superior control of pore size and pore distribution (over wicks made from sintered n-ietals), which in turn is expected to led to significantly improved heat loop performance.

Kazmierczak, M. J.↗
NASA NTRS2000

Development and Characterization of Laser-Induced Incandescence Towards Nanoparticle (Soot) Detection

The production of particulates, notably soot, during combustion has both positive and negative ramifications. Exhaust from diesel engines under load (for example, shifting gears), flickering candle flames and fireplaces all produce soot leaving a flame. From an efficiency standpoint, emission of soot from engines, furnaces or even a simple flickering candle flame represents a loss of useful energy. The emission of soot from diesel engines, furnaces, power generation facilities, incinerators and even simple flames poses a serious environmental problem and health risk. Yet some industries intentionally produce soot as carbon black for use in inks, copier toner, tires and as pigments. Similarly, the presence of soot within flames can act both positively and negatively. Energy transfer from a combustion process is greatly facilitated by the radiative heat transfer from soot yet radiative heat transfer also facilitates the spread of unwanted fires. To understand soot formation and develop control strategies for soot emission/formation, measurements of soot concentration in both practical devices such as engines and controlled laboratory flames are necessary. Laser-induced incandescence (LII) has been developed and characterized to address this need, as described here.

VanderWal, Randy L.↗