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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Experimental Performance Evaluation of a High Speed Permanent Magnet Synchronous Motor and Drive for a Flywheel Application at Different Frequencies

This paper presents the results of an experimental performance characterization study of a high speed, permanent magnet motor/generator (M/G) and drive applied to a flywheel module. Unlike the conventional electric machine the flywheel M/G is not a separated unit; its stator and rotor are integrated into a flywheel assembly. The M/G rotor is mounted on a flywheel rotor, which is magnetically levitated and sealed within a vacuum chamber during the operation. Thus, it is not possible to test the M/G using direct load measurements with a dynamometer and torque transducer. Accordingly, a new in-situ testing method had to be developed. The paper describes a new flywheel M/G and drive performance evaluation technique, which allows the estimation of the losses, efficiency and power quality of the flywheel high speed permanent magnet M/G, while working in vacuum, over wide frequency and torque ranges. This method does not require any hardware modification nor any special addition to the test rig. This new measurement technique is useful for high-speed applications, when applying an external load is technically difficult.

Nagorny, Aleksandr S.↗
NASA NTRS2008

Mechanical Description of the Mars Climate Sounder Instrument

This paper introduces the Mars Climate Sounder (MCS) Instrument of the Mars Reconnaissance Orbiter (MRO) spacecraft. The instrument scans the Martian atmosphere almost continuously to systematically acquire weather and climate observations over time. Its primary components are an optical bench that houses dual telescopes with a total of nine channels for visible and infrared sensing, and a two axis gimbal that provides pointing capabilities. Both rotating joints consist of an integrated actuator with a hybrid planetary/harmonic transmission and a twist cap section that enables the electrical wiring to pass through the rotating joint. Micro stepping is used to reduce spacecraft disturbance torques to acceptable levels while driving the stepper motors. To ensure survivability over its four year life span, suitable mechanical components, lubrication, and an active temperature control system were incorporated. Some life test results and lessons learned are provided to serve as design guidelines for actuator parts and flex cables.

rotating joints↗
NASA NTRS1974

The AIROscope pointing and stabilization system

The AIROscope pointing and stabilization system is described. The system is configured with three gimbal axes and rate integrating gyro stabilization to provide a stable platform for infrared astronomy. Error signals for on and off-axis pointing are derived from a video sensor which also drives a ground station display. Other features of the system include direct drive torque motors and electronic suspension damping. Results of analysis and simulations used to design the control loops, and a pointing error analysis are presented.

Murphy, J. P.↗
NASA NTRS2005

Multipurpose Hyperspectral Imaging System

A hyperspectral imaging system of high spectral and spatial resolution that incorporates several innovative features has been developed to incorporate a focal plane scanner (U.S. Patent 6,166,373). This feature enables the system to be used for both airborne/spaceborne and laboratory hyperspectral imaging with or without relative movement of the imaging system, and it can be used to scan a target of any size as long as the target can be imaged at the focal plane; for example, automated inspection of food items and identification of single-celled organisms. The spectral resolution of this system is greater than that of prior terrestrial multispectral imaging systems. Moreover, unlike prior high-spectral resolution airborne and spaceborne hyperspectral imaging systems, this system does not rely on relative movement of the target and the imaging system to sweep an imaging line across a scene. This compact system (see figure) consists of a front objective mounted at a translation stage with a motorized actuator, and a line-slit imaging spectrograph mounted within a rotary assembly with a rear adaptor to a charged-coupled-device (CCD) camera. Push-broom scanning is carried out by the motorized actuator which can be controlled either manually by an operator or automatically by a computer to drive the line-slit across an image at a focal plane of the front objective. To reduce the cost, the system has been designed to integrate as many as possible off-the-shelf components including the CCD camera and spectrograph. The system has achieved high spectral and spatial resolutions by using a high-quality CCD camera, spectrograph, and front objective lens. Fixtures for attachment of the system to a microscope (U.S. Patent 6,495,818 B1) make it possible to acquire multispectral images of single cells and other microscopic objects.

Mao, Chengye↗
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 NTRS2000

Performance of The Far Ultraviolet Spectroscopic Explorer Mirror Assemblies

The Far Ultraviolet Spectroscopic Explorer is a NASA astrophysics satellite which produces high-resolution spectra in the far-ultraviolet (90.5-118.7 nm bandpass) using a high effective area and low background detectors. The observatory was launched on its three-year mission from Cape Canaveral Air Station on 24 June 1999. The instrument contains four coaligned, normal incidence, off-axis parabolic mirrors which illuminate separate Rowland circle spectrograph channels equipped with holographically ruled diffraction gratings and delay line microchannel plate detectors. The telescope mirrors have a 352 x 387 mm aperture and 2245 mm focal length and are attached to actuator assemblies, which provide on-orbit, tip, tilt, and focus control. Two mirrors are coated with silicon carbide (SiC) and two are coated with lithium fluoride over aluminum (Al:LiF). We describe mirror assembly in-flight optical and mechanical performance. On-orbit measurements of the far-ultraviolet point spread function associated with each mirror are compared to expectations based on pre-flight laboratory measurements and modeling using the Optical Surface Analysis Code and surface metrology data. On-orbit imaging data indicate that the mirrors meet their instrument-level requirement of 50 percent and 95 percent slit transmission for the high- and mid-resolution spectrograph entrance slits, respectively. The degradation of mirror reflectivity during satellite integration and test is also discussed. The far-ultraviolet reflectivity of the SiC- and AlLiF-coated mirrors decreased about six percent and three percent, respectively, between coating and launch. Each mirror is equipped with three actuators, which consist of a stepper motor driving a ball screw via a two-stage planetary gear train. We also discuss the mechanical performance of the mirror assemblies, including actuator performance and thermal effects.

Ohi, Raymond G.↗
NASA NTRS2013

Mechanism for Deploying a Long, Thin-Film Antenna from a Rover

Observations with radio telescopes address key problems in cosmology, astrobiology, heliophysics, and planetary science including the first light in the Universe (Cosmic Dawn), magnetic fields of extrasolar planets, particle acceleration mechanisms, and the lunar ionosphere. The Moon is a unique science platform because it allows access to radio frequencies that do not penetrate the Earth's ionosphere and because its far side is shielded from intense terrestrial emissions. A radio antenna can be realized by using polyimide film as a substrate, with a conducting substance deposited on it. Such an antenna can be rolled into a small volume for transport, then deployed by unrolling, and a robotic rover offers a natural means of unrolling a polyimide film-based antenna. An antenna deployment mechanism was developed that allows a thin film to be deposited onto a ground surface, in a controlled manner, using a minimally actuated rover. The deployment mechanism consists of two rollers, one driven and one passive. The antenna film is wrapped around the driven roller. The passive roller is mounted on linear bearings that allow it to move radially with respect to the driven roller. Springs preload the passive roller against the driven roller, and prevent the tightly wrapped film from unspooling or "bird's nesting" on the driven spool. The antenna deployment mechanism is integrated on the minimally-actuated Axel rover. Axel is a two-wheeled rover platform with a trailing boom that is capable of traversing undulated terrain and overcoming obstacles of a wheel radius in height. It is operated by four motors: one that drives each wheel; a third that controls the rotation of the boom, which orients the body mounted sensors; and a fourth that controls the rover's spool to drive the antenna roller. This low-mass axle-like rover houses its control and communication avionics inside its cylindrical body. The Axel rover teleoperation software has an auto-spooling mode that allows a user to automatically deploy the thin-film antenna at a rate proportional to the wheel speed as it drives the rover along its trajectory. The software allows Axel to deposit the film onto the ground to prevent or minimize relative motion between the film and the terrain to avoid the risk of scraping and antenna with the terrain.

Lazio, Joseph↗
NASA NTRS2007

Control Code for Bearingless Switched-Reluctance Motor

A computer program has been devised for controlling a machine that is an integral combination of magnetic bearings and a switched-reluctance motor. The motor contains an eight-pole stator and a hybrid rotor, which has both (1) a circular lamination stack for levitation and (2) a six-pole lamination stack for rotation. The program computes drive and levitation currents for the stator windings with real-time feedback control. During normal operation, two of the four pairs of opposing stator poles (each pair at right angles to the other pair) levitate the rotor. The remaining two pairs of stator poles exert torque on the six-pole rotor lamination stack to produce rotation. This version is executable in a control-loop time of 40 s on a Pentium (or equivalent) processor that operates at a clock speed of 400 MHz. The program can be expanded, by addition of logic blocks, to enable control of position along additional axes. The code enables adjustment of operational parameters (e.g., motor speed and stiffness, and damping parameters of magnetic bearings) through computer keyboard key presses.

Morrison, Carlos R.↗
NASA NTRS1982

A lightweight electronically commutated dc motor for electric passenger vehicles

A functional model breadboard converter and a rare-earth-cobalt, permanent magnet motor; as well as an engineering model converter and PM motor suitable for vehicle installations were developed and tested. The converter and motor achieved an 88% peak efficiency, a maximum output of 26 kW at 26,000 rpm, and a continuous rating of 15 kW. The system also generated power to the source during braking, with a demonstrated peak power available at the converter terminals of approximately 26 kW at 88% efficiency. Major conclusions include: (1) the SAE J227a(D) driving cycle efficiency for the converter/motor is 86% to 88% when energy available for recovery at the converter terminals is included; (2) the converter initial cost is approximately five times that of the permanent magnet motor, but can be reduced by means of LSI logic and integrated liquid cooled semiconductor packages; and (3) an electronically commutated motor with a liquid cooled converter will operate reliably without service or maintenance for the life of a passenger vehicle.

Echolds, E. F.↗
NASA NTRS2010

In-Situ Focusing Inside a Thermal Vacuum Chamber

Traditionally, infrared (IR) space instruments have been focused by iterating with a number of different thickness shim rings in a thermal vacuum chamber until the focus meets requirements. This has required a number of thermal cycles that are very expensive as they tie up many integration and test (I&T)/ environmental technicians/engi neers work ing three shifts for weeks. Rather than creating a test shim for each iteration, this innovation replaces the test shim and can focus the instrument while in the thermal vacuum chamber. The focus tool consists of three small, piezo-actuated motors that drive two sets of mechanical interface flanges between the instrument optics and the focal- plane assembly, and three optical-displacement metrology sensors that can be read from outside the thermal vacuum chamber. The motors are used to drive the focal planes to different focal distances and acquire images, from which it is possible to determine the best focus. At the best focus position, the three optical displacement metrology sensors are used to determine the shim thickness needed. After the instrument leaves the thermal vacuum chamber, the focus tool is replaced with the precision-ground shim ring. The focus tool consists of two sets of collars, one that mounts to the backside of the interface flange of the instrument optics, and one that mounts to the backside of the interface flange of the focal plane modules. The collars on the instrument optics side have the three small piezo-actuated motors and the three optical displacement metrology systems. Before the instrument is focused, there is no shim ring in place and, therefore, no fasteners holding the focal plane modules to the cameras. Two focus tooling collars are held together by three strong springs. The Orbiting Carbon Observatory (OCO) mission spectrometer was focused this way (see figure). The motor described here had to be moved five times to reach an acceptable focus, all during the same thermal cycle, which was verified using pupil slicing techniques. A focus accuracy of .20.100 microns was achieved.

Liebe, Carl Christian↗
NASA NTRS1989

Electronically Variable Pressure Regulator (EVPR)

A new programmable electronically variable pressure regulator (EVPR) concept accurately controls the local outlet or remote system pressure. It uses an integral pulse width modulated rare earth permanent magnet motor operating in response to redundant pressure transducer feedback signals. The EVPR is a simple single stage device that does not use dynamic seals or pilot valving. Conversion of partial revolution motor torque to poppet lifting force is accomplished by pure flexure action to avoid using bearings. The flexure drive (called the ROTAX) has a variable lead to minimize motor weight and power consumption. Breadboard tests were completed successfully on two critical design elements of the EVPR: the ROTAX and the motor. The ROTAX cable system was tested for 250,000 cycles without failure. The breadboard motor met the basic design requirements including the design torque and power consumption. Prototype parts were fabricated, and testing of the prototype EVPR has started. It is PC computer controlled to facilitate programming, data acquisition and analysis. A lightweight dedicated microprocessor is planned for the flightweight EVPR.

Reinicke, R. H.↗
NASA NTRS2015

RoboGlove-A Grasp Assist Device for Earth and Space

The RoboGlove is an assistive device that can augment human strength, endurance or provide directed motion for use in rehabilitation. RoboGlove is a spinoff of the highly successful Robonaut 2 (R2) system developed as part of a partnership between General Motors and NASA. This extremely lightweight device employs an actuator system based on the R2 finger drive system to transfer part or the entire grasp load from human tendons to artificial ones contained in the glove. Steady state loads ranging from 15 to 20 lbs. and peaks approaching 50 lbs. are achievable. Work is underway to integrate the RoboGlove system with a space suit glove to add strength or reduce fatigue during spacewalks. Tactile sensing, miniaturized electronics, and on-board processing provide sufficient flexibility for applications in many industries. The following describes the design, mechanical/electrical integration, and control features of the glove in an assembly-line configuration and discusses work toward the space suit application.

Diftler, M. A.↗
NASA NTRS1971

Design of a three-phase, 15-kilovolt-ampere static inverter for motor-starting a Brayton space power system

The design of a three-phase, 400-Hz, 15-kVA static inverter for motor-starting the 2- to 15-kWe Brayton electrical space power system is described. The inverter operates from a nominal 56-V dc source to provide a 28-V, rms, quasi-square-wave output. The inverter is capable of supplying a 200-A peak current. Integrated circuitry is used to generate the three-phase, 400-Hz reference signals. Performance data for a drive stage that improves switching speed and provides efficient operation over a range of output current and drive supply voltage are presented. A transformerless, transistor output stage is used.

Frye, R. J.↗
NASA NTRS1999

Integrated Advanced Microwave Sounding Unit-A (AMSU-A). Performance Verification Report: AMSU-A1 Antenna Drive Subsystem, PN 1331720-2, S/N 106

This is the Performance Verification Report, AMSU-A1 Antenna Drive Subsystem, P/N 1331720-2, S/N 106, for the Integrated Advanced Microwave Sounding Unit-A (AMSU-A). The antenna drive subsystem of the METSAT AMSU-A1, S/N 106, P/N 1331720-2, completed acceptance testing per A-ES Test Procedure AE-26002/lD. The test included: Scan Motion and Jitter, Pulse Load Bus Peak Current and Rise Time, Resolver Reading and Position Error, Gain/ Phase Margin, and Operational Gain Margin. The drive motors and electronic circuitry were also tested at the component level. The drive motor test includes: Starting Torque Test, Motor Commutation Test, Resolver Operation/ No-Load Speed Test, and Random Vibration. The electronic circuitry was tested at the Circuit Card Assembly (CCA) level of production; each test exercised all circuit functions. The transistor assembly was tested during the W3 cable assembly (1356941-1) test.

Luu, D.↗
NASA NTRS1978

Applicability of the Remote Mobile Emplacement Package (RMEP) design as a mobility aid for proposed post-84 Mars missions, phase O

The results of study to determine the applicability of the Remote Mobile Emplacement Package (RMEP) design concept as a mobility aid for the proposed post-'84 Mars missions are presented. The RMEP wheel and mobility subsystem parameters: wheel tire size, weight, stowed volume, and environmental effects; obstacle negotiation; reliability and wear; motor and drive train; and electrical power demand were reviewed. Results indicated that: (1) the basic RMEP wheel design would be satisfactory, with additional attention to heating, side loading, tread wear and ultraviolet radiation protection; (2) motor and drive train power requirements on Mars would be less than on Earth; and (3) the mobility electrical power requirements would be small enough to offer the option of operating the Mars mini rover untethered. Payload power required for certain sampling functions would preclude the use of battery power for these missions. Hazard avoidance and reverse direction maneuvers are discussed. Limited examination of vehicle payload integration and thermal design was made, pending establishment of a baseline vehicle/payload design.

Source record↗
NASA NTRS1981

Advanced dc motor controller for battery-powered electric vehicles

A motor generation set is connected to run from the dc source and generate a voltage in the traction motor armature circuit that normally opposes the source voltage. The functional feasibility of the concept is demonstrated with tests on a Proof of Principle System. An analog computer simulation is developed, validated with the results of the tests, applied to predict the performance of a full scale Functional Model dc Controller. The results indicate high efficiencies over wide operating ranges and exceptional recovery of regenerated energy. The new machine integrates both motor and generator on a single two bearing shaft. The control strategy produces a controlled bidirectional plus or minus 48 volts dc output from the generator permitting full control of a 96 volt dc traction motor from a 48 volt battery, was designed to control a 20 hp traction motor. The controller weighs 63.5 kg (140 lb.) and has a peak efficiency of 90% in random driving modes and 96% during the SAE J 227a/D driving cycle.

Belsterling, C. A.↗
NASA NTRS2011

A Hybrid Power Management (HPM) Based Vehicle Architecture

Society desires vehicles with reduced fuel consumption and reduced emissions. This presents a challenge and an opportunity for industry and the government. The NASA John H. Glenn Research Center (GRC) has developed a Hybrid Power Management (HPM) based vehicle architecture for space and terrestrial vehicles. GRC's Electrical and Electromagnetics Branch of the Avionics and Electrical Systems Division initiated the HPM Program for the GRC Technology Transfer and Partnership Office. HPM is the innovative integration of diverse, state-of-the-art power devices in an optimal configuration for space and terrestrial applications. The appropriate application and control of the various power devices significantly improves overall system performance and efficiency. The basic vehicle architecture consists of a primary power source, and possibly other power sources, providing all power to a common energy storage system, which is used to power the drive motors and vehicle accessory systems, as well as provide power as an emergency power system. Each component is independent, permitting it to be optimized for its intended purpose. This flexible vehicle architecture can be applied to all vehicles to considerably improve system efficiency, reliability, safety, security, and performance. This unique vehicle architecture has the potential to alleviate global energy concerns, improve the environment, stimulate the economy, and enable new missions.

Eichenberg, Dennis J.↗
NASA NTRS2000

Flow Quality Measurements in the NASA Ames Upgraded 11-by 11-Foot Transonic Wind Tunnel

Among the many upgrades designed and implemented in the NASA Ames 11-by 11-Foot Transonic Wind Tunnel over the past few years, several directly affect flow quality in the test section: a turbulence reduction system with a honeycomb and two screens, a flow smoothing system in the back leg diffusers, an improved drive motor control system, and a full replacement set of composite blades for the compressor. Prior to the shut-down of the tunnel for construction activities, an 8-foot span rake populated with flow instrumentation was traversed in the test section to fully document the flow quality and establish a baseline against which the upgrades could be characterized. A similar set of measurements was performed during the recent integrated system test trials, but the scope was somewhat limited in accordance with the primary objective of such tests, namely to return the tunnel to a fully operational status. These measurements clearly revealed substantial improvements in flow angularity and significant reductions in turbulence level for both full-span and semi-span testing configurations, thus making the flow quality of the tunnel one of the best among existing transonic facilities.

Amaya, Max A.↗