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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 451 records · Page 25
All sourcesNASA NTRSDOE OSTI
NASA NTRS1970

Improved apparatus for continuous culture of hydrogen-fixing bacteria

Improved apparatus permits the continuous culture of Hydrogenomonas eutropha. System incorporates three essential subsystems - /1/ environmentally isolated culture vessel, /2/ analytical system with appropriate sensors and readout devices, /3/ control system with feedback responses to each analytical measurement.

Foster, J. F.↗
NASA NTRS1978

UAH/NASA Workshop on The Uses of a Tethered Satellite System

Potential applications of the system are categorized into four areas: geological applications, atmospheric applications, electrodynamics and plasma studies, and technology applications. The multiple-use tethered system with feedback control, will be capable of supporting a payload or satellite suspended from the Shuttle cargo bay, at distances up to 100 kilometers from the Shuttle. Experiments proposed include: geomagnetic mapping, lower atmospheric measurements, ionospheric interactions with large space structures, solar wind transport, and magnetohydrodynamic measurements.

Wu, S. T.↗
NASA NTRS1989

Prototype secondary mirror assembly design for the space infrared telescope facility

The authors describe the design of a liquid helium temperature prototype secondary mirror assembly (PSMA) under developement for the NASA Space Infrared Telescope Facility (SIRTF) program. The SIRTF secondary mirror assembly must operate below 4 K and provide highly precise two-axis dynamic tilting (chopping) in addition to the conventional functions needed by the SIRTF observatory. The PSMA design uses a fused quartz mirror kinematically attached at its center to an aluminum cruciform. The mirror/cruciform assembly is driven in tilt about its combined center of mass using a unique flexure pivot and a four-actuator control system with feedback provided by pairs of differential position sensors. The voice coil actuators are mounted on a second flexture-pivoted mass, enhancing servo system stability and isolating the telescope from vibration-induced disturbances. The mirror/cruciform and the reaction mass are attached to opposite sides of an aluminum mounting plate whose dimensional characteristics are nominally identical to those of the aluminum flexure pivot material. The mounting plate is connected to the outer housing by a six-degree-of-freedom focus and centering mechanism using pivoted actuation levers driven by lead screw/harmonic drive/stepper motor assemblies.

Stier, M.↗
NASA NTRS1992

The application of linear actuators for telescope pointing control

A study team at MSFC has conceptually designed two lunar-based telescopes, a 16 m aperture Large Lunar Telescope (LLT) and a 4 m Cluster Telescope Experiment (CTE). The CTE serves as a technology tested for the LLT. The CTE utilizes a hexapod telescope mount to obtain a small gimbal angle that significantly extends the viewing space and observation time from that of a stationary transit telescope. This paper addresses the applicability of six linear actuators to provide limited gimbal rotation of the CTE telescope assembly. Kinematic constraint equations for the hexapod mount have been applied to a six degree-of-freedom rigid body model. Static equilibrium equations have been solved to address configuration design issues, and a feedback tracking control system has been designed and simulated.

Carrington, C. K.↗
NASA NTRS2003

Active/Passive Control of Sound Radiation from Panels using Constrained Layer Damping

A hybrid passive/active noise control system utilizing constrained layer damping and model predictive feedback control is presented. This system is used to control the sound radiation of panels due to broadband disturbances. To facilitate the hybrid system design, a methodology for placement of constrained layer damping which targets selected modes based on their relative radiated sound power is developed. The placement methodology is utilized to determine two constrained layer damping configurations for experimental evaluation of a hybrid system. The first configuration targets the (4,1) panel mode which is not controllable by the piezoelectric control actuator, and the (2,3) and (5,2) panel modes. The second configuration targets the (1,1) and (3,1) modes. The experimental results demonstrate the improved reduction of radiated sound power using the hybrid passive/active control system as compared to the active control system alone.

Gibbs, Gary P.↗
NASA NTRS2005

Vision and "Hand-Eye" Coordination for the Fujitsu HOAP-2 Humanoid Robot

Software was developed for a Fujitsu HOAP-2 humanoid robot to demonstrate that such "human form" robots can be used to perform useful tasks in an unknown environment; specifically, that they can operate with or in the place of humans to carry out construction operations necessary for space exploration, such as building or maintaining planetary surface habitats for humans. This paper describes the autonomous vision and hand-eye coordination software that enables the HOAP-2 to locate and manipulate objects. Simple vision and pattern detection algorithms including color filtering, noise filtering, image segmentation, orientation filters, and a feedback controlled tracking system enable the robot to locate marked building materials in the workspace. Experimentally determined spatial mappings associate locations in the visual field with the arm joint angles and trajectories necessary to reach these locations, allowing the robot to reach for and manipulate the building materials. These capabilities, when combined with locomotion capabilities, enable the robot to operate autonomously in an unknown workspace.

Moore, Jeffrey D.↗
NASA NTRS2014

Design and Lessons Learned on the Development of a Cryogenic Pupil Select Mechanism (PSM)

Calibration and testing of the instruments on the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) is being performed by the use of a cryogenic, full-field, optical simulator that was constructed for this purpose. The Pupil Select Mechanism (PSM) assembly is one of several mechanisms and optical elements that compose the Optical Telescope Element SIMulator, or OSIM. The PSM allows for several optical elements to be inserted into the optical plane of OSIM, introducing a variety of aberrations, distortions, obscurations, and other calibration states into the pupil plane. The following discussion focuses on the details of the design evolution, analysis, build, and test of this mechanism along with the challenges associated with creating a sub arc-minute positioning mechanism operating in an extreme cryogenic environment. In addition, difficult challenges in the control system design will be discussed including the incorporation of closed-loop feedback control into a system that was designed to operate in an open-loop fashion.

PSM Design↗
NASA NTRS2014

Design and Lessons Learned on the Development of a Cryogenic Pupil Select Mechanism Used in the Testing and Calibration of the Integrated Science Instrument Module (ISIM) on the James Webb Space Telescope (JWST)

Calibration and testing of the instruments on the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) is being performed by the use of a cryogenic, full-field, optical simulator that was constructed for this purpose. The Pupil Select Mechanism (PSM) assembly is one of several mechanisms and optical elements that compose the Optical Telescope Element SIMulator, or OSIM. The PSM allows for several optical elements to be inserted into the optical plane of OSIM, introducing a variety of aberrations, distortions, obscurations, and other calibration states into the pupil plane. The following discussion focuses on the details of the design evolution, analysis, build, and test of this mechanism along with the challenges associated with creating a sub arc-minute positioning mechanism operating in an extreme cryogenic environment. In addition, difficult challenges in the control system design will be discussed including the incorporation of closed-loop feedback control into a system that was designed to operate in an open-loop fashion.

Testing↗
NASA NTRS2014

Design and Lessons Learned on the Development of a Cryogenic Pupil Select Mechanism used in the Testing and Calibration of the Integrated Science Instrument Module (ISIM) on the James Webb Space Telescope (JWST)

Calibration and testing of the instruments on the Integrated Science Instrument Module (ISIM) of the James Webb Space Telescope (JWST) is being performed by the use of a cryogenic, full-field, optical simulator that was constructed for this purpose. The Pupil Select Mechanism (PSM) assembly is one of several mechanisms and optical elements that compose the Optical Telescope Element SIMulator, or OSIM. The PSM allows for several optical elements to be inserted into the optical plane of OSIM, introducing a variety of aberrations, distortions, obscurations, and other calibration states into the pupil plane. The following discussion focuses on the details of the design evolution, analysis, build, and test of this mechanism along with the challenges associated with creating a sub arc-minute positioning mechanism operating in an extreme cryogenic environment. In addition, difficult challenges in the control system design will be discussed including the incorporation of closed-loop feedback control into a system that was designed to operate in an open-loop fashion.

Mitchell, Alissa↗