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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS2007

Rover Wheel-Actuated Tool Interface

A report describes an interface for utilizing some of the mobility features of a mobile robot for general-purpose manipulation of tools and other objects. The robot in question, now undergoing conceptual development for use on the Moon, is the All-Terrain Hex-Limbed Extra-Terrestrial Explorer (ATHLETE) rover, which is designed to roll over gentle terrain or walk over rough or steep terrain. Each leg of the robot is a six-degree-of-freedom general purpose manipulator tipped by a wheel with a motor drive. The tool interface includes a square cross-section peg, equivalent to a conventional socket-wrench drive, that rotates with the wheel. The tool interface also includes a clamp that holds a tool on the peg, and a pair of fold-out cameras that provides close-up stereoscopic images of the tool and its vicinity. The field of view of the imagers is actuated by the clamp mechanism and is specific to each tool. The motor drive can power any of a variety of tools, including rotating tools for helical fasteners, drills, and such clamping tools as pliers. With the addition of a flexible coupling, it could also power another tool or remote manipulator at a short distance. The socket drive can provide very high torque and power because it is driven by the wheel motor.

Matthews, Janet↗
NASA NTRS2010

Development and Acceptance Testing of the Dual Wheel Mechanism for the Tunable Filter Imager Cryogenic Instrument on the JWST

The James Webb Space Telescope (JWST) will carry four scientific instruments, one of which is the Tunable Filter Imager (TFI), which is an instrument within the Fine Guidance Sensor. The Dual Wheel (DW) mechanism is being designed, built and tested by COM DEV Ltd. under contract from the Canadian Space Agency. The DW mechanism includes a pupil wheel (PW) holding seven coronagraphic masks and two calibration elements and a filter wheel (FW) holding nine blocking filters. The DW mechanism must operate at both room temperature and at 35K. Successful operation at 35K comprises positioning each optical element with the required repeatability, for several thousand occasions over the five year mission. The paper discusses the results of testing geared motors and bearings at the cryogenic temperature. In particular bearing retainer design and PGM-HT material, the effects of temperature gradients across bearings and the problems associated with cooling mechanisms down to cryogenic temperatures. The results of additional bearing tests are described that were employed to investigate an abnormally high initial torque experienced at cryogenic temperatures. The findings of these tests, was that the bearing retainer and the ball/race system could be adversely affected by the large temperature change from room temperature to cryogenic temperature and also the temperature gradient across the bearing. The DW mechanism is now performing successfully at both room temperature and at cryogenic temperature. The life testing of the mechanism is expected to be completed in the first quarter of 2010.

Leckie, Martin↗
NASA NTRS2003

Hopping Robot with Wheels

A small prototype mobile robot is capable of (1) hopping to move rapidly or avoid obstacles and then (2) moving relatively slowly and precisely on the ground by use of wheels in the manner of previously reported exploratory robots of the "rover" type. This robot is a descendant of a more primitive hopping robot described in "Minimally Actuated Hopping Robot" (NPO- 20911), NASA Tech Briefs, Vol. 26, No. 11 (November 2002), page 50. There are many potential applications for robots with hopping and wheeled-locomotion (roving) capabilities in diverse fields of endeavor, including agriculture, search-and-rescue operations, general military operations, removal or safe detonation of land mines, inspection, law enforcement, and scientific exploration on Earth and remote planets. The combination of hopping and roving enables this robot to move rapidly over very rugged terrain, to overcome obstacles several times its height, and then to position itself precisely next to a desired target. Before a long hop, the robot aims itself in the desired hopping azimuth and at a desired takeoff angle above horizontal. The robot approaches the target through a series of hops and short driving operations utilizing the steering wheels for precise positioning.

Barlow, Edward↗
NASA NTRS2003

Lightweight, Self-Deployable Wheels

Ultra-lightweight, self-deployable wheels made of polymer foams have been demonstrated. These wheels are an addition to the roster of cold hibernated elastic memory (CHEM) structural applications. Intended originally for use on nanorovers (very small planetary-exploration robotic vehicles), CHEM wheels could also be used for many commercial applications, such as in toys. The CHEM concept was reported in "Cold Hibernated Elastic Memory (CHEM) Expandable Structures" (NPO-20394), NASA Tech Briefs, Vol. 23, No. 2 (February 1999), page 56. To recapitulate: A CHEM structure is fabricated from a shape-memory polymer (SMP) foam. The structure is compressed to a very small volume while in its rubbery state above its glass-transition temperature (Tg). Once compressed, the structure can be cooled below Tg to its glassy state. As long as the temperature remains <Tg the structure remains compacted (in a cold hibernated state), even when the external compressive forces are removed. When the structure is subsequently heated above Tg, it returns to the rubbery state, in which a combination of elasticity and the SMP effect cause it to expand (deploy) to its original size and shape. Once thus deployed, the CHEM structure can be rigidified by cooling below Tg to the glassy state. The structure could be subsequently reheated above Tg and recompacted. The compaction/deployment/rigidification cycle could be repeated as many times as needed.

Chmielewski, Artur↗
NASA NTRS2013

Characterizing the Performance of the Wheel Electrostatic Spectrometer

A Wheel Electrostatic Spectrometer has been developed as a surveying tool to be incorporated into a Martian rover design. Electrostatic sensors with various protruding cover insulators are embedded into a prototype rover wheel. When these insulators come into contact with a surface, a charge develops on the cover insulator through tribocharging. A charge spectrum is created by analyzing the accumulated charge on each of the dissimilar cover insulators. This charge spectrum can be used to determine differences in Martian regolith properties. In this study, we analyzed the repeatability of the measurements for this sensor package and found that the sensor repeatability lies within one standard deviation of the noise in the signal. In addition, we tested the need for neutralizing the surface charge on the cover insulators and discovered a need to discharge the sensor cover insulators after each revolution. Future work includes an electronics redesign to reduce noise and a Martian pressure static elimination tool that can be used to neutralize the charge on the sensor cover insulators after each wheel revolution.

Johansen, M. R.↗
NASA NTRS2013

Robotic Two-Wheeled Vehicle

A robotic two-wheeled vehicle comprising a connection body interposed between the two wheels are described. A drum can be coaxially located in a central region of the connection body and can support a hollow arm projecting radially from the drum. A tether can be inserted in the arm and connected to a second drum. Instruments and sensors can be accommodated in a case housed inside each wheel.

Nesnas, Issa A. D.↗
NASA NTRS2014

Robotic Two-Wheeled Vehicle

A robotic two-wheeled vehicle comprising a connection body interposed between the two wheels are described. A drum can be coaxially located in a central region of the connection body and can support a hollow arm projecting radially from the drum. A tether can be inserted in the arm and connected to a second drum. Instruments and sensors can be accommodated in a case housed inside each wheel.

Nesnas, Issa A. D.↗
NASA NTRS2016

High-Performance Reaction Wheel Optimization for Fine-Pointing Space Platforms: Minimizing Induced Vibration Effects on Jitter Performance plus Lessons Learned from Hubble Space Telescope for Current and Future Spacecraft Applications

The Hubble Space Telescope (HST) applies large-diameter optics (2.5-m primary mirror) for diffraction-limited resolution spanning an extended wavelength range (approx. 100-2500 nm). Its Pointing Control System (PCS) Reaction Wheel Assemblies (RWAs), in the Support Systems Module (SSM), acquired an unprecedented set of high-sensitivity Induced Vibration (IV) data for 5 flight-certified RWAs: dwelling at set rotation rates. Focused on 4 key ratios, force and moment harmonic values (in 3 local principal directions) are extracted in the RWA operating range (0-3000 RPM). The IV test data, obtained under ambient lab conditions, are investigated in detail, evaluated, compiled, and curve-fitted; variational trends, core causes, and unforeseen anomalies are addressed. In aggregate, these values constitute a statistically-valid basis to quantify ground test-to-test variations and facilitate extrapolations to on-orbit conditions. Accumulated knowledge of bearing-rotor vibrational sources, corresponding harmonic contributions, and salient elements of IV key variability factors are discussed. An evolved methodology is presented for absolute assessments and relative comparisons of macro-level IV signal magnitude due to micro-level construction-assembly geometric details/imperfections stemming from both electrical drive and primary bearing design parameters. Based upon studies of same-size/similar-design momentum wheels' IV changes, upper estimates due to transitions from ground tests to orbital conditions are derived. Recommended HST RWA choices are discussed relative to system optimization/tradeoffs of Line-Of-Sight (LOS) vector-pointing focal-plane error driven by higher IV transmissibilities through low-damped structural dynamics that stimulate optical elements. Unique analytical disturbance results for orbital HST accelerations are described applicable to microgravity efforts. Conclusions, lessons learned, historical context/insights, and perspectives on future applications are given; these previously unpublished data and findings represents a valuable resource for fine-pointing spacecraft or space-based platforms using RWAs, Control Moment Gyros (CMGs), Momentum Wheels, or other ball-bearing-based rotational units.

Hasha, Martin D.↗
NASA NTRSDate not supplied

Lunar Rover Optimization Platform for Wheel Traction Studies

Robotic mobility systems expand the reach of future scientific and exploration missions to celestial bodies. Understanding the traction performance of these systems is necessary knowledge that informs mission-level requirements, such as power budgets and navigation envelopes. This paper covers the design, development, and verification of the four wheeled Lunar Rover Optimization Platform (LROP). This mass optimized platform is targeted to emulate future medium class rovers weighing up to 90 kg. The LROP has the ability to conduct various wheel design experiments such as obstacle traversal, slope ascent, and drawbar pull over a wheel loading range of 4.5 to 22.7 kg. The platform also has the ability to shift its center of gravity (CG) laterally and longitudinally to explore the CG shift effects on mobility performance. This knowledge is valuable for future rover designers exploring different payload packaging solutions. In this paper results from obstacle traversal test with varying angle of attack (AOA) and longitudinal CG position are reported along with results from slope ascent testing which proved-out the LROPs capabilities.

Stephen Gerdts↗
NASA NTRS2020

Autonomous Navigation over Europa Analogue Terrain for an Actively Articulated Wheel-on-Limb Rover

The ocean world Europa is a prime target forexploration given its potential habitability [1]. We proposea mobile robotic system that is capable of autonomouslytraversing hundreds of meters to visit multiple sites of intereston a Europan analogue surface. Due to the topology of Europanterrain being largely unknown, it is desired that this mobilitysystem traverse a large variety of terrain types. The mobilitysystem should also be capable of crossing unstructured terrainin an autonomous manner given the communications limitationsbetween Earth and Europa.A wheel-on-limb robotic rover is presented that may activelyconform to terrain features up to 1.5 wheel diameters tall whiledriving. The robot uses a sampling-based motion planner togenerate paths that leverage its unique locomotive capabilities.The planner assesses terrain hazards and wheel workspacelimits as obstacles. It may also select a mobility mode basedon predicted energy usage and the need for limb articulationon the terrain being traversed. This autonomous mobility wasevaluated on the chaotic salt-evaporite terrain found in DeathValley, CA, an analogue to the Europan surface. Over the courseof 38 trials, the rover autonomously traversed 435m of extremeterrain while maintaining a rate of 0.64 traverse ending failuresfor every 10m driven.

Meirion-Griffith, Gareth↗
NASA NTRS1924

Experiments on the resistance of airplane wheels and radiators

Experiments were made on the resistance of four airplane wheels of different sizes and coverings and two Lamblin radiators. The results show the important influence of the wheel coverings. The closing of a shutter, which was fitted to one of the radiators, considerably lessened the resistance.

WHEELS - RESISTANCE↗
NASA NTRS2005

Prospecting for In Situ Resources on the Moon and Mars Using Wheel-Based Sensors

The Apollo and Russian missions during 1970's were reviewed to rediscover the type and distribution of minerals on the Moon. This study revealed that the Moon is a relatively barren place in mineral content when compared with the Earth. Results from the Lunar minerals brought back to Earth, indicate that the Moon lacks water, hydroxyl ions, and carbon based minerals. Our approach to prospecting utilizes a vehicle with sensors embedded in a wheel that allow measurements while the vehicle is in motion. Once a change in soil composition is detected, decision making software stops the vehicle and analytical instruments perform a more definitive analysis of the soil. The focus of this paper is to describe the instrumentation and data from the wheel-based sensors.

moon↗
NASA NTRS1966

Lateral ring metal elastic wheel absorbs shock loading

Lateral ring metal elastic wheel absorbs practically all shock loading when operated over extremely rough terrain and delivers only a negligible shock residue to associated suspension components. The wheel consists of a rigid aluminum assembly to which lateral titanium ring flexible elements with treads are attached.

Galan, L.↗
NASA NTRS1970

Tandem wheel drop-legs for standard truck trailer

Tandem wheel drop-leg device provides a semitrailer with fore and aft mobility that allows it to be moved without a prime mover. The modified drop-legs have trunnion dual wheels and an adjustable brace.

Cantwell, W.↗
NASA NTRS1971

Phase locking of field sequential color wheel for small TV camera

System employs synchronous motor driven by deflection waveform of TV and connected directly to color filter wheel to phase lock wheel to deflection unit. Innovation stabilizes color response of small TV cameras and allows for small, lightweight installations. Problems associated with motor phase changes are cited.

Niemyer, L. L.↗
NASA NTRS1972

Effect of environmental torques on short-term attitude prediction for a rolling-wheel spacecraft in a sun-synchronous orbit

A numerical evaluation and an analysis of the effects of environmental disturbance torques on the attitude of a hexagonal cylinder rolling wheel spacecraft were performed. The resulting perturbations caused by five such torques were found to be very small and exhibited linearity such that linearized equations of motion yielded accurate results over short periods and the separate perturbations contributed by each torque were additive in the sense of superposition. Linearity of the torque perturbations was not affected by moderate system design changes and persisted for torque-to-angular momentum ratios up to 100 times the nominal expected value. As these conditions include many possible applications, similar linear behavior might be anticipated for other rolling-wheel spacecraft.

Hodge, W. F.↗
NASA NTRS1973

Momentum wheel with magnetic bearings

An engineering model of a momentum wheel is described that is suspended by magnetic bearings. It consists of a mechanical assembly on the right, and associated electronics on the left. The momentum wheel is mounted at the center of the rotor shaft and the magnetic bearings are on each end. The rotor is magnetically suspended so there is no physical contact between the rotor and the support structure. The system, therefore, can operate directly in the vacuum environment without lubrication; and it has virtually unlimited operating lifetime, independent of speed.

Veillette, L. J.↗