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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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
NASA NTRS2014

Design Considerations for Miniaturized Control Moment Gyroscopes for Rapid Retargeting and Precision Pointing of Small Satellites

This paper presents the design as well as characterization of a practical control moment gyroscope (CMG) based attitude control system (ACS) for small satellites in the 15-20 kilogram mass range performing rapid retargeting and precision pointing maneuvers. The paper focuses on the approach taken in the design of miniaturized CMGs while considering the constraints imposed by the use of commercial off-the-shelf (COTS) components as well as the size of the satellite. It is shown that a hybrid mode is more suitable for COTS based moment exchange actuators; a mode that uses the torque amplification of CMGs for rapid retargeting and direct torque capabilities of the flywheel motors for precision pointing. A simulation is provided to demonstrate on-orbit slew and pointing performance.

Patankar, Kunal↗
NASA NTRS1989

Dynamic Torque Calibration Unit

Proposed dynamic torque calibration unit (DTCU) measures torque in rotary actuator components such as motors, bearings, gear trains, and flex couplings. Unique because designed specifically for testing components under low rates. Measures torque in device under test during controlled steady rotation or oscillation. Rotor oriented vertically, supported by upper angular-contact bearing and lower radial-contact bearing that floats axially to prevent thermal expansion from loading bearings. High-load capacity air bearing available to replace ball bearings when higher load capacity or reduction in rate noise required.

Agronin, Michael L.↗
NASA NTRS2005

NASA Glenn Research Center Program in High Power Density Motors for Aeropropulsion

Electric drive of transport-sized aircraft propulsors, with electric power generated by fuel cells or turbo-generators, will require electric motors with much higher power density than conventional room-temperature machines. Cryogenic cooling of the motor windings by the liquid hydrogen fuel offers a possible solution, enabling motors with higher power density than turbine engines. Some context on weights of various systems, which is required to assess the problem, is presented. This context includes a survey of turbine engine weights over a considerable size range, a correlation of gear box weights and some examples of conventional and advanced electric motor weights. The NASA Glenn Research Center program for high power density motors is outlined and some technical results to date are presented. These results include current densities of 5,000 A per square centimeter current density achieved in cryogenic coils, finite element predictions compared to measurements of torque production in a switched reluctance motor, and initial tests of a cryogenic switched reluctance motor.

Brown, Gerald V.↗
NASA NTRS2014

Primer Stepper Motor Nomenclature, Definition, Performance and Recommended Test Methods

There has been an unfortunate lack of standardization of the terms and components of stepper motor performance, requirements definition, application of torque margin and implementation of test methods. This paper will address these inconsistencies and discuss in detail the implications of performance parameters, affects of load inertia, control electronics, operational resonances and recommended test methods. Additionally, this paper will recommend parameters for defining and specifying stepper motor actuators. A useful description of terms as well as consolidated equations and recommended requirements is included.

Starin, Scott↗
NASA NTRS1982

Transistorized PWM inverter-induction motor drive system

This paper describes the development of a transistorized PWM inverter-induction motor traction drive system. A vehicle performance analysis was performed to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of inverter and motor specifications. The inverter was a transistorized three-phase bridge using General Electric power Darlington transistors. The description of the design and development of this inverter is the principal object of this paper. The high-speed induction motor is a design which is optimized for use with an inverter power source. The primary feedback control is a torque angle control with voltage and torque outer loop controls. A current-controlled PWM technique is used to control the motor voltage. The drive has a constant torque output with PWM operation to base motor speed and a constant horsepower output with square wave operation to maximum speed. The drive system was dynamometer tested and the results are presented.

Peak, S. C.↗
NASA NTRS1987

Variable-Reluctance Motor For Electric Vehicles

Report describes research on variable-reluctance electric-motor drive for eventual use in electric-vehicle propulsion. Primary design and performance criteria were torque and power output per unit mass of motor, cost, and drive efficiency. For each criterion, optimized drive design developed, and designs unified to yield single electric-vehicle drive. Scaled-down motor performed as expected. Prototype of paraplegic lift operated by toggle switch and joystick. Lift plugs into household electrical outlet for recharging when not in use.

Lang, Jeffrey H.↗
NASA NTRS1993

Field-Oriented Control Of Induction Motors

Field-oriented control system provides for feedback control of torque or speed or both. Developed for use with commercial three-phase, 400-Hz, 208-V, 5-hp motor. Systems include resonant power supply operating at 20 kHz. Pulse-population-modulation subsystem selects individual pulses of 20-kHz single-phase waveform as needed to synthesize three waveforms of appropriate lower frequency applied to three phase windings of motor. Electric actuation systems using technology currently being built to peak powers of 70 kW. Amplitude of voltage of effective machine-frequency waveform determined by momentary frequency of pulses, while machine frequency determined by rate of repetition of overall temporal pattern of pulses. System enables independent control of both voltage and frequency.

Burrows, Linda M.↗
DOE OSTI2020

Computational model for predicting the performance of fluid-powered longiudinal piston modules and motors.

A Matlab-based computational model line code has been developed for predicting the performance of fluid-powered longitudinal piston modules and motors. A system of equations has been developed based upon applying the conservation of mass to a control volume defined by a reciprocating piston. The method results in a differential equation that predicts the pressure gradient in the control volume as a function of rotor rotation angle. The model uses an integration scheme to predict the pressure state in the control volume. The orifice equation is used to predict the flowrate in and out of the control volume. From the resulting solution the torque and speed characteristics of the motor configuration can be predicted, optimized, or tailored for a specific requirement.SAND2019-13983 M Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.

Taylor, Michael↗
NASA NTRS1993

Parametric motion control of robotic arms: A biologically based approach using neural networks

A neural network based system is presented which is able to generate point-to-point movements of robotic manipulators. The foundation of this approach is the use of prototypical control torque signals which are defined by a set of parameters. The parameter set is used for scaling and shaping of these prototypical torque signals to effect a desired outcome of the system. This approach is based on neurophysiological findings that the central nervous system stores generalized cognitive representations of movements called synergies, schemas, or motor programs. It has been proposed that these motor programs may be stored as torque-time functions in central pattern generators which can be scaled with appropriate time and magnitude parameters. The central pattern generators use these parameters to generate stereotypical torque-time profiles, which are then sent to the joint actuators. Hence, only a small number of parameters need to be determined for each point-to-point movement instead of the entire torque-time trajectory. This same principle is implemented for controlling the joint torques of robotic manipulators where a neural network is used to identify the relationship between the task requirements and the torque parameters. Movements are specified by the initial robot position in joint coordinates and the desired final end-effector position in Cartesian coordinates. This information is provided to the neural network which calculates six torque parameters for a two-link system. The prototypical torque profiles (one per joint) are then scaled by those parameters. After appropriate training of the network, our parametric control design allowed the reproduction of a trained set of movements with relatively high accuracy, and the production of previously untrained movements with comparable accuracy. We conclude that our approach was successful in discriminating between trained movements and in generalizing to untrained movements.

Bock, O.↗
NASA NTRS2012

Miniaturization of Planar Horn Motors

There is a great need for compact, efficient motors for driving various mechanisms including robots or mobility platforms. A study is currently underway to develop a new type of piezoelectric actuators with significantly more strength, low mass, small footprint, and efficiency. The actuators/motors utilize piezoelectric actuated horns which have a very high power density and high electromechanical conversion efficiency. The horns are fabricated using our recently developed novel pre-stress flexures that make them thermally stable and increases their coupling efficiency. The monolithic design and integrated flexures that pre-stresses the piezoelectric stack eliminates the use of stress bolt. This design allows embedding solid-state motors and actuators in any structure so that the only macroscopically moving parts are the rotor or the linear translator. The developed actuator uses a stack/horn actuation and has a Barth motor configuration, which potentially generates very large torque and speeds that do not require gearing. Finite element modeling and design tools were investigated to determine the requirements and operation parameters and the results were used to design and fabricate a motor. This new design offers a highly promising actuation mechanism that can potentially be miniaturized and integrated into systems and structures. It can be configured in many shapes to operate as multi-degrees of freedom and multi-dimensional motors/actuators including unidirectional, bidirectional, 2D and 3D. In this manuscript, we are reporting the experimental measurements from a bench top design and the results from the efforts to miniaturize the design using 2x2x2 mm piezoelectric stacks integrated into thin plates that are of the order of3 x 3x 0.2 cm.

horn actuation↗
NASA NTRS2013

Acoustic Mechanical Feedthroughs

Electromagnetic motors can have problems when operating in extreme environments. In addition, if one needs to do mechanical work outside a structure, electrical feedthroughs are required to transport the electric power to drive the motor. In this paper, we present designs for driving rotary and linear motors by pumping stress waves across a structure or barrier. We accomplish this by designing a piezoelectric actuator on one side of the structure and a resonance structure that is matched to the piezoelectric resonance of the actuator on the other side. Typically, piezoelectric motors can be designed with high torques and lower speeds without the need for gears. One can also use other actuation materials such as electrostrictive, or magnetostrictive materials in a benign environment and transmit the power in acoustic form as a stress wave and actuate mechanisms that are external to the benign environment. This technology removes the need to perforate a structure and allows work to be done directly on the other side of a structure without the use of electrical feedthroughs, which can weaken the structure, pipe, or vessel. Acoustic energy is pumped as a stress wave at a set frequency or range of frequencies to produce rotary or linear motion in a structure. This method of transferring useful mechanical work across solid barriers by pumping acoustic energy through a resonant structure features the ability to transfer work (rotary or linear motion) across pressure or thermal barriers, or in a sterile environment, without generating contaminants. Reflectors in the wall of barriers can be designed to enhance the efficiency of the energy/power transmission. The method features the ability to produce a bi-directional driving mechanism using higher-mode resonances. There are a variety of applications where the presence of a motor is complicated by thermal or chemical environments that would be hostile to the motor components and reduce life and, in some instances, not be feasible. A variety of designs that have been designed, fabricated and tested will be presented

piezoelectric devices↗
NASA NTRS2007

The Effect of Manipulating Subject Mass on Lower Extremity Torque Patterns During Locomotion

During locomotion, humans adapt their motor patterns to maintain coordination despite changing conditions (Reisman et al., 2005). Bernstein (1967) proposed that in addition to the present state of a given joint, other factors, including limb inertia and velocity, must be taken into account to allow proper motion to occur. During locomotion with added mass counterbalanced using vertical suspension to maintain body weight, vertical ground reaction forces (GRF's) increase during walking but decrease during running, suggesting that adaptation may be velocity-specific (De Witt et al., 2006). It is not known, however, how lower extremity joint torques adapt to changes in inertial forces. The purpose of this investigation was to examine the effects of increasing body mass while maintaining body weight upon lower-limb joint torque during walking and running. We hypothesized that adaptations in joint torque patterns would occur with the addition of body mass.

DeWitt, John K.↗
NASA NTRS1970

Brushless direct-current motor with stationary armature and field

Electronically commutated dc motor has an active fixed field winding, and active fixed armature winding, and passive rotor. By use of brushless dc motor switching technique, motor provides continuous controllable and reversible torque without use of sliding contacts.

Studer, P. A.↗
NASA NTRS1987

Common drive unit

The Common Drive Unit (CDU) is a high reliability rotary actuator with many versatile applications in mechanism designs. The CDU incorporates a set of redundant motor-brake assemblies driving a single output shaft through differential. Tachometers provide speed information in the AC version. Operation of both motors, as compared to the operation of one motor, will yield the same output torque with twice the output speed.

Ellis, R. C.↗
NASA NTRS1992

Levitation of YBa2Cu3O(7-x) superconductor in a variable magnetic field

The influence of both a linear alternating and rotational magnetic field component on the levitation behavior of a YBa2Cu3O(7-x) superconductor was examined. The transition from a plastic regime of levitation to an elastic one, induced by an alternating field component, was observed. An elastic regime in contrast to a plastic one is characterized by the unique position of stable levitation and field frequency dependence of relaxation time to this position. It was concluded that the vibrations of a magnet levitated above the superconductor can induce a transition from a plastic regime of levitation to an elastic one. It was found that a rotational magnetic field component induced rotations of a levitated superconductor. Rotational frictional motion of flux lines is likely to be an origin of torque developed. A prototype of a motor based on a levitated superconductor rotor is proposed.

Terentiev, Alexander N.↗
NASA NTRS1985

Motor control for a brushless DC motor

This invention relates to a motor control system for a brushless DC motor having an inverter responsively coupled to the motor control system and in power transmitting relationship to the motor. The motor control system includes a motor rotor speed detecting unit that provides a pulsed waveform signal proportional to rotor speed. This pulsed waveform signal is delivered to the inverter to thereby cause an inverter fundamental current waveform output to the motor to be switched at a rate proportional to said rotor speed. In addition, the fundamental current waveform is also pulse width modulated at a rate proportional to the rotor speed. A fundamental current waveform phase advance circuit is controllingly coupled to the inverter. The phase advance circuit is coupled to receive the pulsed waveform signal from the motor rotor speed detecting unit and phase advance the pulsed waveform signal as a predetermined function of motor speed to thereby cause the fundamental current waveform to be advanced and thereby compensate for fundamental current waveform lag due to motor winding reactance which allows the motor to operate at higher speeds than the motor is rated while providing optimal torque and therefore increased efficiency.

Peterson, William J.↗