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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 NTRS2003

Flux-Based Deadbeat Control of Induction-Motor Torque

An improved method and prior methods of deadbeat direct torque control involve the use of pulse-width modulation (PWM) of applied voltages. The prior methods are based on the use of stator flux and stator current as state variables, leading to mathematical solutions of control equations in forms that do not lend themselves to clear visualization of solution spaces. In contrast, the use of rotor and stator fluxes as the state variables in the present improved method lends itself to graphical representations that aid in understanding possible solutions under various operating conditions. In addition, the present improved method incorporates the superposition of high-frequency carrier signals for use in a motor-self-sensing technique for estimating the rotor shaft angle at any speed (including low or even zero speed) without need for additional shaft-angle-measuring sensors.

Kenny, Barbara H.↗
NASA NTRS2002

Development of Micro Air Reconnaissance Vehicle as a Test Bed for Advanced Sensors and Electronics

This paper describes the development of a Micro/Mini Air Reconnaissance Vehicle for advanced sensors and electronics at NASA Langley Research Center over the last year. This vehicle is expected to have a total weight of less than four pounds, a design velocity of 40 mph, an endurance of 15-20 minutes, and a maximum range of 5km. The vehicle has wings that are simple to detach yet retain the correct alignment. The upper fuselage surface has a quick release hatch used to access the interior and also to mount the varying propulsion systems. The sensor suite developed for this vehicle consists of a Pitot-static measurement system for determining air speed, an absolute pressure measurement for determining altitude, magnetic direction measurement, and three orthogonal gyros to determine body angular rates. Swarming GPS-guidance and in-flight maneuvering is discussed, as well as design and installation of some other advance sensors like MEMS microphones, infrared cameras, GPS, humidity sensors, and an ultrasonic sonar sensor. Also low cost, small size, high performance control and navigation system for the Micro Air Vehicle is discussed. At the end, laboratory characterization of different sensors, motors, propellers, and batteries will be discussed.

Shams, Qamar A.↗
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 NTRS2021

Feasibility Analysis of Unmanned Aerial Vehicle Based on Tensegrity Structure

For future unmanned aerial vehicles to be ubiquitous, they need to be safe to other aircraft and people on the ground even in the event of unintended collisions. Unfortunately, this is difficult for current rigid designs as a crash of all but the smallest aircraft will have a significant impact on its target. As an alternative, this pa-per explores using a soft tensegrity structure (interconnected cables and rods) as a lightweight, robust chassis for a UAS and analyze its ability to achieve stable, controllable flight and mitigate damage during a collision. Tensegrity structures are three dimensional geometric constructions which are able to undergo severe deformations without permanent damage, and can immediately return to their original shape. Experiments and analysis are performed using a simple physics simulation environment, allowing for rapid design iteration and thorough exploration of system behavior. We test multiple configurations of the vehicle to understand impacts of changing various physical characteristics, and take limitations such as modern propeller thrust coefficients and motor speeds into account to ensure our results are inline with those of a real world vehicle. We ultimately find that such a vehicle has considerable real world potential, and that a physical prototype could theoretically be constructed and flown with current technology.

Bjorn Johnson↗
NASA NTRS1975

Preliminary design report, Large Space Telescope OTA/SI Phase B study: High speed area photometer

A photometer is examined which combines several features from separate instruments into a single package. The design presented has both point and area photometry capability with provision for inserting filters to provide spectral discrimination. The electronics provide for photon counting mode for the point detectors and both photon counting and analog modes for the area detector. The area detector also serves as a target locating device for the point detectors. Topics discussed include: (1) electronic equipment requirements, (2) optical properties, (3) structural housing for the instrument, (4) motors and other mechanical components, (5) ground support equipment, and (6) environment control for the instrument. Engineering drawings and block diagrams are shown.

Source record↗
NASA NTRS1994

Data Acquisition Systems

In the mid-1980s, Kinetic Systems and Langley Research Center determined that high speed CAMAC (Computer Automated Measurement and Control) data acquisition systems could significantly improve Langley's ARTS (Advanced Real Time Simulation) system. The ARTS system supports flight simulation R&D, and the CAMAC equipment allowed 32 high performance simulators to be controlled by centrally located host computers. This technology broadened Kinetic Systems' capabilities and led to several commercial applications. One of them is General Atomics' fusion research program. Kinetic Systems equipment allows tokamak data to be acquired four to 15 times more rapidly. Ford Motor company uses the same technology to control and monitor transmission testing facilities.

Source record↗
NASA NTRS1980

A new controller for battery-powered electric vehicles

This paper describes the development, under a NASA/DOE contract, of a new concept for efficient and reliable control of battery-powered vehicles. It avoids the detrimental effects of pulsed-power controllers like the SCR 'chopper' by using rotating machines to meter continuous currents to the traction motor. The concept is validated in a proof-of-principle demonstration system and a complete vehicle is simulated on an analog computer. Test results show exceptional promise for a full-scale system. Optimum control strategies to minimize controller weight are developed by means of the simulated vehicle. The design for an Engineering Model is then prepared in the form of a practical, compact two-bearing package with forced air cooling. Predicted performance is outstanding, with controller efficiency of over 90% at high speed.

Belsterling, C. A.↗
NASA NTRS1975

Motor run-up system

A starting system is described for bringing a large synchronous motor up to speed to prevent large power line disturbances at the moment the motor is connected to the power line. The system includes (1) a digital counter which generates a count determined by the difference in frequency between the power line and a small current generated by the synchronous motor; (2) a latch which stores the count; and (3) a comparator which compares the stored count with a newly generated count to determine whether the synchronous motor is accelerating or decelerating. Signals generated by the counter and comparator control the current to a clutch that couples a starting motor to the large synchronous motor.

Daeges, J. J.↗
NASA NTRS2007

Recommendations for Refinement and Validation of Intermittent Artificial Gravity

The IMAG Pilot Study, recently completed at the University of Texas Medical Branch, filled in the second major gap in knowledge standing in the way of development of a practical Short Radius Centrifuge (SRC) and the use of Artificial Gravity (AG) as a multi-system countermeasure to combat the deconditioning associated with extended weightlessness. (The first challenge, to adapt rapidly rotating subjects to permit unlimited head movements without excessive motion sickness, was achieved in a series of studies at MIT involving incremental increases in head and centrifuge velocity.) It remained to be demonstrated that intermittent exposure to AG, at only one hour per day for 21 days, would have any positive effect on slowing or eliminating of deconditioning. Bed-rested normal subjects were used as a ground analog for astronauts in weightlessness. The results are clearly positive for the key physiological systems of interest: cardiovascular, muscle, and bone. No functionally relevant changes were observed in immune, cognitive, or sensory-motor function. Furthermore, we found that our initial concerns about the inability of deconditioned subjects to withstand daily centrifugation without syncope were misplaced. These encouraging initial results clearly support the further development of AG protocols. We recommend, as the next steps, the integration of a controlled exercise device on the SRC to determine the synergy between AG and exercise. Coupled with appropriate exercise device(s) the AG protocol will be tuned to-ward an optimal prescription for minimum exposure duration and frequency, maximum AG level and SRC speed.. Performance of these next steps will require extensive use of bed-rest/centrifuge facilities and eventually validation using an SRC in space. A space SRC could be placed in the ISS or on a planetary surface.

Young, Lauren R.↗
NASA NTRS2004

Controllable Sonar Lenses and Prisms Based on ERFs

Sonar-beam-steering devices of the proposed type would contain no moving parts and would be considerably smaller and less power-hungry, relative to conventional multiple-beam sonar arrays. The proposed devices are under consideration for installation on future small autonomous underwater vehicles because the sizes and power demands of conventional multiple-beam arrays are excessive, and motors used in single-beam mechanically scanned systems are also not reliable. The proposed devices would include a variety of electrically controllable acoustic prisms, lenses, and prism/lens combinations both simple and compound. These devices would contain electrorheological fluids (ERFs) between electrodes. An ERF typically consists of dielectric particles floating in a dielectric fluid. When an electric field is applied to the fluid, the particles become grouped into fibrils aligned in rows, with a consequent increase in the viscosity of the fluid and a corresponding increase in the speed of sound in the fluid. The change in the speed of sound increases with an increase in the applied electric field. By thus varying the speed of sound, one varies the acoustic index of refraction, analogously to varying the index of refraction of an optical lens or prism. In the proposed acoustic devices, this effect would be exploited to control the angles of refraction of acoustic beams, thereby steering the beams and, in the case of lenses, controlling focal lengths.

Bar-Cohen, Yoseph↗
DOE OSTI2024

High-bandwidth Dynamic Load Emulation of Mechanical Systems using Electric Drives

Machine drives are versatile systems that can be programmed to emulate a variety of mechanical loads. In this paper, we walk through the modeling and control framework of a shaft-coupled dual-motor drive system that is programmed to emulate a fictitious mechanical system. We quantitatively evaluate the control performance of such a system and derive a theoretical limit that explains its inaccuracy at high operating frequencies. To overcome this problem, we propose an alternate control structure that achieves the same control objective at high frequencies as well. After suitable adjustments are made to the controller, we validate its performance using simulation results.

machine drives ,load emulation, speed-torque chara↗
DOE OSTI2022

SMC Reinforced by Recycled or Textile Carbon Fiber

There is a significant need to expand material options for SMC that has traditionally used glass fibers for decades. There are several integral issues related to chopping and conveying a range of materials including glass, carbon, basalt, thermoplastic tapes, and recycled fibers. These are in a variety of forms including continuous tows, discontinuous agglomerates such as pyrolyzed carbon fibers that could be used to produce a range of SMC intermediates. Standard/conventional SMC processing is limited to cutting rotors specifically for glass and compounding with thermoset polyesters and some epoxies. The multi-material, multi-format line developed in this project is flexible to enable custom conveying and uses an interchangeable rotor dedicated for specific material types. The overall tasks undertaken in this project included: evaluation of the fiber feed mechanism, effect of textile grade carbon, evaluating servo motor controlling of conveyor, evaluate doctor box resin feed, evaluate compaction unit, evaluation of different formulations, and develop automation such as PLC programming. The new multi-material SMC line Version 2 (SCM-V2) incorporated servo motors over induction motors which gave the overall cutter system precision control and made it quiet. The addition of a 14-roll compaction unit at the end of the line in SMC-V2 enabled higher material wet out which was a limitation in the SMC Version 1 (SMC-V1). The cutters were further updated to reduce the cantilever overhang of the fiber which enabled more uniform cut lengths for glass, carbon, and basalt fibers. The overall instrumentation and system control including a remote control operation was enabled in the SMC-V2. The line speed is capable of 10-20 ft/minute. The cutting modules were designed and engineered for cutting glass, basalt and textile grade carbon in 300k and 450-600k format widths. The cutting trials were established for a range of fiber types. The study also demonstrated the utility of the line to cut and produce basalt fiber SMC. Initial trials were conducted on the properties from recycled carbon fiber (rCF) mats in epoxy resin. Overall, the Covid19 situation constrained the team from accessing the SMC line for over 18 months. Despite this challenge major advancements were made.

36 MATERIALS SCIENCE↗
NASA NTRS1996

Spacecraft with gradual acceleration of solar panels

A spacecraft (8) includes a movable appendage such as solar panels (12) operated by a stepping motor (28) driven by pulses (311). In order to reduce vibration andor attitude error, the drive pulses are generated by a clock down-counter (312) with variable count ratio. Predetermined desired clock ratios are stored in selectable memories (314a-d), and the selected ratio (R) is coupled to a comparator (330) together with the current ratio (C). An up-down counter (340) establishes the current count-down ratio by counting toward the desired ratio under the control of the comparator; thus, a step change of solar panel speed never occurs. When a direction change is commanded, a flag signal generator (350) disables the selectable memories, and enables a further store (360), which generates a count ratio representing a very slow solar panel rotational rate, so that the rotational rate always slows to a low value before direction is changed. The principles of the invention are applicable to any movable appendage.

Merhav, Tamir R.↗
DOE OSTI2024

Autonomous Emergency Landing for Fixed-Wing Aircraft with Energy-Constrained Closed-Loop Prediction

Here this paper presents a new approach for autonomous motion planning for aircraft suffering from a loss-of-thrust emergency. Specifically, we show how modifications to the Closed-Loop Rapidly exploring Random Trees (CL-RRT) framework combined with controlled energy dissipation can enable rapid and effective kinodynamic motion planning. This CL-RRT Glide algorithm uses closed-loop prediction not only for node connections but also to estimate the remaining energy and prune infeasible paths. This greatly speeds up the search process, which is essential for emergency situations. In addition, we improve the ability of the gliding aircraft to reach a goal position and energy state. We do so by creating a Dissipative Total Energy Control Scheme (TECS). Dissipative TECS enables the glider to lose excess altitude in order to reach a desired energy level. Simulation results illustrate how the proposed methods enable faster motion planning. We also integrate the system into a small unmanned aerial vehicle system and experimentally demonstrate autonomous glide planning and execution during a motor-failure event. This type of algorithm can primarily benefit unmanned aircraft but can also serve to assist pilots in stressful emergency situations.

42 ENGINEERING↗
NASA NTRS2003

Improved Multiple-DOF SAW Piezoelectric Motors

Surface-acoustic-wave (SAW) piezoelectric motors of a proposed type would be capable of operating in multiple degrees of freedom (DOFs) simultaneously and would be amenable to integration into diverse structures and mechanisms. These motors would be compact and structurally simple and would not contain bearings or lead screws. One example of a particularly useful motor of this type would be a two-dimensional- translation stage. Another such example would be a self-actuated spherical joint that could be made to undergo controlled, simultaneous rotations about two orthogonal axes: Such a motor could serve as a mechanism for aiming an "eyeball" camera or as a compact transducer in, and an integral part of, a joint in a robot arm. The multiple-DOF SAW piezoelectric motors as now proposed would be successors to the ones reported in "Multiple-DOF Surface-Acoustic-Wave Piezoelectric Motors" (NPO-20735), NASA Tech Briefs, Vol. 24, No. 12 (December 2000), page 5b. The basic principle of operation of a multiple-DOF SAW piezoelectric motor is a straightforward extension of that of single-DOF SAW piezoelectric motors, which have been reported in several previous NASA Tech Briefs articles: For example, in the case of a linear SAW piezoelectric motor, piezoelectric transducers at opposite ends of a stator excite surface acoustic waves that travel along the surface of the stator. An object (denoted the slider) is pressed against the stator with sufficient pressure (in practice .300 MPa) that it remains in frictional contact with the stator at all times. The slider rides the crests of the waves and is thereby made to move along the surface of the stator. The direction of motion (forward or backward) is controlled by selecting the relative phase of waves generated by the two piezoelectric transducers. The speed increases with the amplitude of the waves and thus with the magnitude of the voltage applied to the transducers.

Bar-Cohen, Yoseph↗
NASA NTRSDate not supplied

Cruise Propulsion System Thermal Analysis for NASA’s X-57 “Maxwell” Mod II Configuration

The X-57 “Maxwell” is NASA’s flight demonstrator for distributed electric propulsion technologies. The X-57 Mod II configuration is designed to test the electric cruise propulsion system for X-57 and features an electric cruise motor mounted in an integral nacelle on each wing. The electric motors and associated control equipment for X-57 Mod II are air-cooled; therefore, they require adequate cooling airflow to stay within temperature limits set by the X-57 project in all relevant flight conditions. A computational flow analysis was conducted to estimate the internal flow properties of the X-57 Mod II cruise nacelles in three critical flight conditions. These flow properties were then used to determine the boundary conditions for individual component thermal models, which were used to estimate individual component operating temperatures. The results indicated that the low-speed, low-altitude initial takeoff climb during hot day conditions was the sizing condition from a cooling perspective. The analysis found that the cooling flowpaths in the X-57 Mod II cruise nacelles are adequate to provide cooling to most of the components with the appropriate amount of thermal margin. The two components that are not anticipated to have the appropriate margin can be accommodated with a small (< 2°C) adjustment to the project operating limitations.

Nicholas K. Borer↗
NASA NTRS1994

Feasibility study of superconducting LSM rocket launcher system

A feasibility study is presented concerning an application of a superconducting linear synchronous motor (LSM) to a large-scale rocket launcher, whose acceleration guide tube of LSM armature windings is constructed 1,500 meters under the ground. The rocket is released from the linear launcher just after it gets to a peak speed of about 900 kilometers per hour, and it flies out of the guide tube to obtain the speed of 700 kilometers per hour at the height of 100 meters above ground. The linear launcher is brought to a stop at the ground surface for a very short time of 5 seconds by a quick control of deceleration. Very large current variations in the single-layer windings of the LSM armature, which are produced at the higher speed region of 600 to 900 kilometers per hour, are controlled successfully by adopting the double-layer windings. The proposed control method makes the rocket launcher ascend stably in the superconducting LSM system, controlling the Coriolis force.

Yoshida, Kinjiro↗
NASA NTRS2010

Development of a Fan for Future Space Suit Applications

NASA's next generation space suit system will place new demands on the fan used to circulate breathing gas through the ventilation loop of the portable life support system. Long duration missions with frequent extravehicular activities (EVAs), the requirement for significant increases in reliability and durability, and a mission profile that imposes strict limits on weight, volume and power create the basis for a set of requirements that demand more performance than is available from existing fan designs. This paper describes the development of a new fan to meet these needs. A centrifugal fan was designed with a normal operating speed of approximately 39,400 rpm to meet the ventilation flow requirements while also meeting the aggressive minimal packaging, weight and power requirements. The prototype fan also operates at 56,000 rpm to satisfy a second operating condition associated with a single fan providing ventilation flow to two spacesuits connected in series. This fan incorporates a novel nonmetallic "can" to keep the oxygen flow separate from the motor electronics, thus eliminating ignition potential. The nonmetallic can enables a small package size and low power consumption. To keep cost and schedule within project bounds a commercial motor controller was used. The fan design has been detailed and implemented using materials and approaches selected to address anticipated mission needs. Test data is presented to show how this fan performs relative to anticipated ventilation requirements for the EVA portable life support system. Additionally, data is presented to show tolerance to anticipated environmental factors such as acoustics, shock, and vibration. Recommendations for forward work to progress the technology readiness level and prepare the fan for the next EVA space suit system are also discussed.

Paul. Heather L.↗