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Results for “ELECTROMAGNETIC CONTROL”

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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Six degrees of freedom vibration isolation using electromagnetic suspension

Experimental data are presented for modeling an electromagnet. Control laws are considered with and without flux feedback and with position and orientation information of the suspended body. Base motion and sensor noise are the principal disturbances. Proper selection of the geometrical operating point minimizes the passive coupling above the bandwidth of the control and filtering can attenuate the high frequency content of sensor noise. Six electromagnets are arranged in a configuration which optimizes the load support and provides control over all six degrees of freedom of the suspended body. The design is based on experimental data generated with a specially designed test facility. Application for suspension of a gravity wave antenna is discussed.

Lee, Sang-Il↗
NASA NTRS1975

Improved magnetic suspension technique

Technique combines electromagnetic coil with polarized permanent magnets. This reduces power consumption of electromagnetic units and improves response of magnetic suspension systems, by increasing their sensitivity to changes in current controlling electromagnet.

Studer, P. A.↗
NASA NTRS2013

Manager's Role in Electromagnetic Interference (EMI) Control

This presentation captures the essence of electromagnetic compatibility (EMC) engineering from a project manager's perspective. It explains the basics of EMC and the benefits to the project of early incorporation of EMC best practices. The EMC requirement products during a project life cycle are identified, along with the requirement verification methods that should be utilized. The goal of the presentation is to raise awareness and simplify the mystique surrounding electromagnetic compatibility for managers that have little or no electromagnetics background

Safety↗
NASA NTRS1990

Feedback controlled electrostatic and electromagnetic sample positioners

Four different sample positioners are discussed. The four systems share a common operating principle in that the sample positioning is achieved by feedback controlled forces which can be electrostatic, dielectrophoretic, or electromagnetic. The first system is the electrostatic liquid drop positioner which operates at the near ambient position. The second system is the tetrahedral electrostatic positioner which is being developed for the high temperature materials processing in vacuum. The third system is essentially the the same tetrahedral system above except that the position control is achieved by dielectrophoretic forces in the pressurized gas environment. Finally, the feasibility of a feedback controlled electromagnetic positioner is discussed.

Rhim, Won-Kyu↗
NASA NTRS2008

A Cryogenic High-Power-Density Bearingless Motor for Future Electric Propulsion

The NASA Glenn Research Center (GRC) is developing a high-power-density switched-reluctance cryogenic motor for all-electric and pollution-free flight. However, cryogenic operation at higher rotational speeds markedly shortens the life of mechanical rolling element bearings. Thus, to demonstrate the practical feasibility of using this motor for future flights, a non-contact rotor-bearing system is a crucial technology to circumvent poor bearing life that ordinarily accompanies cryogenic operation. In this paper, a bearingless motor control technology for a 12-8 (12 poles in the stator and 8 poles in the rotor) switched-reluctance motor operating in liquid nitrogen (boiling point, 77 K (-196 C or -321 F)) was presented. We pushed previous disciplinary limits of electromagnetic controller technique by extending the state-of-the-art bearingless motor operating at liquid nitrogen for high-specific-power applications. The motor was levitated even in its nonlinear region of magnetic saturation, which is believed to be a world first for the motor type. Also we used only motoring coils to generate motoring torque and levitation force, which is an important feature for developing a high specific power motor.

Choi, Benjamin↗
NASA NTRS1972

Assessment and control of spacecraft electromagnetic interference

Design criteria are presented to provide guidance in assessing electromagnetic interference from onboard sources and establishing requisite control in spacecraft design, development, and testing. A comprehensive state-of-the-art review is given which covers flight experience, sources and transmission of electromagnetic interference, susceptible equipment, design procedure, control techniques, and test methods.

Source record↗
NASA NTRS1974

Electromagnetic containerless processing requirements and recommended facility concept and capabilities for space lab

Containerless melting, reaction, and solidification experiments and processes which potentially can lead to new understanding of material science and production of new or improved materials in the weightless space environment are reviewed in terms of planning for spacelab. Most of the experiments and processes discussed are amenable to the employment of electromagnetic position control and electromagnetic induction or electron beam heating and melting. The spectrum of relevant properties of materials, which determine requirements for a space laboratory electromagnetic containerless processing facility are reviewed. Appropriate distributions and associated coil structures are analyzed and compared on the basis of efficiency, for providing the functions of position sensing, control, and induction heating. Several coil systems are found capable of providing these functions. Exchangeable modular coils in appropriate sizes are recommended to achieve the maximum power efficiencies, for a wide range of specimen sizes and resistivities, in order to conserve total facility power.

Frost, R. T.↗
NASA NTRS1972

Magnetic bearings for spacecraft

Magnetic bearings have been successfully applied to motorized rotor systems in the multi-kilogram range, at speeds up to 1200 radians per second. These engineering models also indicated the need for continued development in specific areas to make them feasible for spacecraft applications. Significant power reductions have recently been attained. A unique magnetic circuit, combining permanent magnets with electromagnetic control, has a bidirectional forcing capability with improved current sensitivity. The multi-dimensional nature of contact-free rotor support is discussed. Stable continuous radial suspension is provided by a rotationally symmetric permanent magnet circuit. Two bearings, on a common shaft, counteract the normal instability perpendicular to the rotational axis. The axial direction is servoed to prevent contact. A new bearing technology and a new field of application for magnetics is foreseen.

Studer, P. A.↗
NASA NTRS1990

Free-floating experiments in orbiter and space station

Manned spacecraft will never be free of acceleration perturbations due to necessary motions of crewmembers. However, in most cases, the perturbations can be minimized or even isolated from sensitive experiments when required. The principal disturbances and methods of isolation are described. As the crew moves about the spacecraft, no external forces are applied and the average acceleration remains near zero. External force will be exerted when jets are fired for spacecraft attitude control or translation, and these must be transferred to the microgravity experiments. Transitory acceleration and vibration are produced by crew and equipment. The most significant on Orbiter have been wall push-offs used for body translation within the spacecraft, the exercise conducted on a treadmill within the middeck area, closing doors of stowage compartments and the vibration of some machinery, such as a sample centrifuge. For short periods of perhaps a few minutes, crew and equipment motion can be largely inhibited, but not for much longer intervals. It may be necessary to mount especially sensitive experiments on an isolation table, which can greatly reduce the acceleration transferred to the experiment. Either weak mechanical springs or, even better, a computer-controlled electromagnetic suspension can be used to effectively insulate the table from vibration at frequencies above about 0.01 Hz. Another option is to free-float an experiment table within the spacecraft. All of the above-mentioned perturbations can be eliminated for some minutes if the entire experiment package is allowed to free-float within the spacecraft until a wall contact is made. Package acceleration levels should be maintainable below 10(exp -8) g sub o in this way.

Garriott, Owen K.↗
NASA NTRS1990

Real-time measurement of materials properties at high temperatures by laser produced plasmas

Determination of elemental composition and thermophysical properties of materials at high temperatures, as visualized in the context of containerless materials processing in a microgravity environment, presents a variety of unusual requirements owing to the thermal hazards and interferences from electromagnetic control fields. In addition, such information is intended for process control applications and thus the measurements must be real time in nature. A new technique is described which was developed for real time, in-situ determination of the elemental composition of molten metallic alloys such as specialty steel. The technique is based on time-resolved spectroscopy of a laser produced plasma (LPP) plume resulting from the interaction of a giant laser pulse with a material target. The sensitivity and precision were demonstrated to be comparable to, or better than, the conventional methods of analysis which are applicable only to post-mortem specimens sampled from a molten metal pool. The LPP technique can be applied widely to other materials composition analysis applications. The LPP technique is extremely information rich and therefore provides opportunities for extracting other physical properties in addition to the materials composition. The case in point is that it is possible to determine thermophysical properties of the target materials at high temperatures by monitoring generation and transport of acoustic pulses as well as a number of other fluid-dynamic processes triggered by the LPP event. By manipulation of the scaling properties of the laser-matter interaction, many different kinds of flow events, ranging from shock waves to surface waves to flow induced instabilities, can be generated in a controllable manner. Time-resolved detection of these events can lead to such thermophysical quantities as volume and shear viscosities, thermal conductivity, specific heat, mass density, and others.

Kim, Yong W.↗
NASA NTRS1992

The large-angle magnetic suspension test fixture

As part of a NASA effort to develop the technology and techniques required to demonstrate the magnetic suspension of objects over wide ranges of attitudes, a small-scale demonstration project was undertaken. The objectives here are to suspend a cylindrical element containing a permanent magnet core, to demonstrate stability and control in five degrees-of-freedom, and to permit controlled rotation of the model in one degree-of-freedom over the full range of 360 deg. Further constraints are that all suspension and control electromagnets are to be behind a flat plane, located some distance from the model. Since this is a ground-based experiment and in order to maintain generality, the plane is chosen to be horizontal with the model levitated above the plane by repulsive forces.

Britcher, Colin P.↗
NASA NTRS1996

Results of the Stable Microgravity Vibration Isolation Flight Experiment

This paper presents an overview of the STABLE microgravity isolation system developed and successfully flight tested in October 1995. A description of the hardware design and operational principles is given. A sample of the measured flight data is presented, including an evaluation of attenuation performance provided by the actively controlled electromagnetic isolation system. Preliminary analyses of flight data show that the acceleration environment aboard STABLE's isolated platform was attenuated by a factor of more than 25 between 0.1 and 100 Hz. STABLE was developed under a cooperative agreement between National Aeronautics and Space Administration, Marshall Space Flight Center, and McDonnell Douglas Aerospace. The flight hardware was designed, fabricated, integrated, tested, and delivered to the Cape during a five month period.

Edberg, Donald↗
NASA NTRS2001

Making the EZ Choice

Analytical Mechanics Associates, Inc. (AMA), of Hampton, Virginia, created the EZopt software application through Small Business Innovation Research (SBIR) funding from NASA's Langley Research Center. The new software is a user-friendly tool kit that provides quick and logical solutions to complex optimal control problems. In its most basic form, EZopt converts process data into math equations and then proceeds to utilize those equations to solve problems within control systems. EZopt successfully proved its advantage when applied to short-term mission planning and onboard flight computer implementation. The technology has also solved multiple real-life engineering problems faced in numerous commercial operations. For instance, mechanical engineers use EZopt to solve control problems with robots, while chemical plants implement the application to overcome situations with batch reactors and temperature control. In the emerging field of commercial aerospace, EZopt is able to optimize trajectories for launch vehicles and perform potential space station- keeping tasks. Furthermore, the software also helps control electromagnetic devices in the automotive industry.

Source record↗
NASA NTRS1999

Detecting Controller Malfunctions in Electromagnetic Environments: Design and Analysis of the Detector - Part 2

Verifying the integrity of control computers in adverse operating environments is a key issue in the development, validation, certification, and operation of critical control systems. Future commercial aircraft will necessitate flight-critical systems with high reliability requirements for stability augmentation, flutter suppression, and guidance and control. Operational integrity of such systems in adverse environments must be validated. This paper considers the problem of applying dynamic detection techniques to monitoring the integrity of fault tolerant control computers in critical applications. Specifically, this paper considers the detection of malfunctions in an aircraft flight control computer (FCC) that is subjected to electromagnetic environment (EME) disturbances during laboratory testing. A dynamic monitoring strategy is presented and demonstrated for the FCC from glideslope engaged until flare under clear air turbulence conditions using a detailed simulation of the B737 Autoland. The performance of the monitoring system is analyzed.

Belcastro, Celeste M.↗
NASA NTRS1999

Detecting Controller Malfunctions in Electromagnetic Environments: Modeling and Estimation of Nominal System Function - Part 1

A strategy for detecting control law calculation errors in critical flight control computers during laboratory validation testing is presented. This paper addresses Part I of the detection strategy which involves the use of modeling of the aircraft control laws and the design of Kalman filters to predict the correct control commands. Part II of the strategy which involves the use of the predicted control commands to detect control command errors is presented in the companion paper.

Weinstein, Bernice↗