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All sourcesNASA NTRSDOE OSTI
NASA NTRS2009

Motion Cueing Algorithm Modification for Improved Turbulence Simulation

Atmospheric turbulence cueing produced by flight simulator motion systems has been less than satisfactory because the turbulence profiles have been attenuated by the motion cueing algorithms. Cardullo and Ellor initially addressed this problem by directly porting the turbulence model output to the motion system. Reid and Robinson addressed the problem by employing a parallel aircraft model, which is only stimulated by the turbulence inputs and adding a filter specially designed to pass the higher turbulence frequencies. There have been advances in motion cueing algorithm development at the Man-Machine Systems Laboratory, at SUNY Binghamton. In particular, the system used to generate turbulence cues has been studied. The Reid approach, implemented by Telban and Cardullo, was employed to augment the optimal motion cueing algorithm installed at the NASA LaRC Simulation Laboratory, driving the Visual Motion Simulator. In this implementation, the output of the primary flight channel was added to the output of the turbulence channel and then sent through a non-linear cueing filter. The cueing filter is an adaptive filter; therefore, it is not desirable for the output of the turbulence channel to be augmented by this type of filter. The likelihood of the signal becoming divergent was also an issue in this design. After testing on-site it became apparent that the architecture of the turbulence algorithm was generating unacceptable cues. As mentioned above, this cueing algorithm comprised a filter that was designed to operate at low bandwidth. Therefore, the turbulence was also filtered, augmenting the cues generated by the model. If any filtering is to be done to the turbulence, it will utilize a filter with a much higher bandwidth, above the frequencies produced by the aircraft response to turbulence. The authors have developed an implementation wherein only the signal from the primary flight channel passes through the nonlinear cueing filter. This paper discusses three new algorithms. Testing shows that the new methods provide the pilot with a more realistic sensation of turbulence; the cues are not attenuated by algorithm. Results of offline testing show the credibility of the models. Offline test verification was based primarily on the evaluation of the power spectral density of the outputs and the time response.

Ercole, Anthony V.↗
NASA NTRS2019

SAFE50 Reference Design Study for Large-Scale High-Density Low-Altitude UAS Operations in Urban Areas

Enabling safe, routine, and high-density flight operations of small UAS at low-altitude over heavily populated urban centers presents a difficult challenge for emerging UAS Traffic Management (UTM) system concepts. Urban operations by definition involve flight over people, property, and infrastructure. Low-altitude urban environments - such as urban canyons – are one of the most difficult areas for UTM to consider. Mission concepts require routine operations in a cluttered radio-frequency (RF) environment with degraded or denied Global Positioning System (GPS) reception. Flights with any appreciable distance will be beyond visual and communications line-of-sight from ground operators. Timely detection and response to emergencies and onboard failures, which is critical for safe aircraft operation, will be difficult. This work seeks to establish a feasible reference autonomy architecture for autonomous vehicles in an urban UTM system, then verifying and validating this architecture within a complete UTM concept point-design and systems analysis study. In this paper, we present the results from the NASA SAFE50 conceptual design and systems study that investigates the trade-space of urban UTM operations. This advanced conceptual design study develops a feasible, verified, validated point-design solution. The SAFE50 point-design concept places emphasis on advanced, highly-autonomous, and highly-capable vehicles that favors intelligent onboard autonomy over direct human control with today's technologies and operating in today's urban environments. This paper focuses on an general overview of the design study, highlighting decisions made in the architectural solution. This paper will presents a summary of the study, architectures, and requirements. We present an overview of the architecture designs as derived from the top-level UTM system. The point-design has been implemented in both simulation and through flight testing of hardware design prototypes. The results from simulation and flight testing as part of the verification and validation process of the reference design study.

Ippolito, Corey A.↗
NASA NTRS1971

An inventory of aeronautical ground research facilities. Volume 4: Engineering flight simulation facilities

The general purpose capabilities of government and industry in the area of real time engineering flight simulation are discussed. The information covers computer equipment, visual systems, crew stations, and motion systems, along with brief statements of facility capabilities. Facility construction and typical operational costs are included where available. The facilities provide for economical and safe solutions to vehicle design, performance, control, and flying qualities problems of manned and unmanned flight systems.

Pirrello, C. J.↗
NASA NTRS1972

Development of an unsteady water tunnel.

A detailed description is given of an unsteady hydrodynamic flow facility located at the University of Alabama in Huntsville, Alabama. This facility is used to measure unsteady pressures and forces and to acquire hydrogen bubble flow visualization data pertaining to bodies submerged in different types of accelerating flow. Various data acquisition systems are delineated along with typical experimental results acquired using cylindrical models. The method of facility operation and theoretical design considerations are shown along with a comparison between calculations and experimental results. This comparison indicates that the theoretical design procedures sufficiently represented the physical phenomenon for facility design.

Schutzenhofer, L.↗
NASA NTRS1973

Human factor roles in design of teleoperator systems

Teleoperator systems are considered, giving attention to types of teleoperators, a manned space vehicle attached manipulator, a free-flying teleoperator, a surface exploration roving vehicle, the human factors role in total system design, the manipulator system, the sensor system, the communication system, the control system, and the mobility system. The role of human factors in the development of teleoperator systems is also discussed, taking into account visual systems, an operator control station, and the manipulators.

Janow, C.↗
NASA NTRS1981

An analytical pilot rating method for highly elastic aircraft

An analytical method was developed to predict pilot ratings for highly elastic aircraft subject to severe mode interactions between rigid body and elastic dynamics. An extension of the standard optimal control model of pilot response was made to include the hypothesis that the pilot controls the system with an internal model consisting of the slowly varying part of the aircraft dynamics. This modified optimal control model was analytically evaluated for a longitudinal pitch tracking task on a large flexible aircraft. Parametric variations in the undamped natural frequencies of two symmetric elastic modes were made to induce varying amounts of mode interaction. The model proved successful in discriminating when the pilot can or cannot visually separate rigid from elastic pitch response in the turbulence excited tracking task. This method shows considerable promise in making it possible to investigate such mode interaction effects on handling qualities in the preliminary design stage of new aircraft.

Swaim, R. L.↗
NASA NTRS1985

Langley Research Center Standard for the Evaluation of Socket Welds

A specification utilized for the nondestructive evaluation of socket type pipe joints at Langley Research Center (LaRC) is discussed. The scope of hardware shall include, but is not limited to, all common pipe fittings: tees, elbows, couplings, caps, and so forth, socket type flanges, unions, and valves. In addition, the exterior weld of slip on flanges shall be inspected using this specification. At the discretion of the design engineer, standard practice engineer, Fracture Mechanics Engineering Section, Pressure Systems Committee, or other authority, four nondestructive evaluation techniques may be utilized exclusively, or in combination, to inspect socket type welds. These techniques are visual, radiographic, magnetic particle, and dye penetrant. Under special circumstances, other techniques (such as eddy current or ultrasonics) may be required and their application shall be guided by the appropriate sections of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (B&PVC).

Berry, R. F., Jr.↗
NASA NTRS1989

Design and development of a facility for compressible dynamic stall studies of a rapidly pitching airfoil

A facility for the study of dynamic stall of an airfoil undergoing a transient ramp-type pitching motion is described. The facility can produce pitch rates of 3600 deg/sec to an angle of attack of 60 deg by using a specially designed hydraulic drive with feedback control. The ramp motion generator can also generate arbitrary motion of the airfoil and thus can simulate an arbitrary aircraft maneuver. A unique airfoil support system allows unobstructed flow visualization including the complete airfoil contour, thus permitting the use of nonintrusive optical diagnostic methods for flow measurement close to the surface as well as simultaneous far-field measurements. Schlieren pictures obtained during the study reveal the instantaneous density gradients associated with dynamic stall, even under conditions of very low Mach numbers.

Chandrasekhara, M. S.↗
NASA NTRS1991

Point-Diffraction Interferometer For Flow Experiments

Improved point-diffraction interferometer used in both real-time visualization and recording of supersonic and transonic flow fields about airfoils and other test bodies in wind tunnels. System relatively insensitive to vibrations, but very sensitive to optical quality of wind-tunnel windows. Designed to handle higher laser powers and to use available light efficiently.

Bachalo, William D.↗
NASA NTRS1992

An experimental investigation of the flow in a diffusing S-duct

Compressible, subsonic flow through a diffusing S-duct has been experimentally investigated. Benchmark aerodynamic data are presented for flow through a representative S-duct configuration. The collected data would be beneficial to aircraft inlet designers and is suitable for the validation of computational codes. Measurements of the 3D velocity field and total and static pressures were obtained at five cross-sectional planes. Surface static pressures and flow visualization also helped to reveal flowfield characteristics. All reported tests were conducted with an inlet centerline Mach number of 0.6 and a Reynolds number, based on the inlet centerline velocity and duct inlet diameter, of 2.6 x 10 exp 6. The results show that a large region of streamwise flow separation occurred within the duct. Transverse velocity components indicate that the duct curvature induces strong pressure driven secondary flows, which evolve into a large pair of counter-rotating vortices. These vortices convect the low momentum fluid of the boundary layer toward the center of the duct, degrading both the uniformity and magnitude of the total pressure profile.

Wellborn, S. R.↗
NASA NTRS1992

An experimental investigation of the flow in a diffusing S-duct

Compressible, subsonic flow through a diffusing S-duct has been experimentally investigated. Benchmark aerodynamic data are presented for flow through a representative S-duct configuration. The collected data would be beneficial to aircraft inlet designers and is suitable for the validation of computational codes. Measurements of the 3D velocity field and total and static pressures were obtained at five cross-sectional planes. Surface static pressures and flow visualization also helped to reveal flow field characteristics. All reported tests were conducted with an inlet centerline Mach number of 0.6 and a Reynolds number, based on the inlet centerline velocity and duct inlet diameter, of 2.6 x 10(exp 6). The results show that a larger region of streamwise flow separation occurred within the duct. Details about the separated flow region, including mechanisms which drive this complicated flow phenomenon, are discussed. Transverse velocity components indicate that the duct curvature induces strong pressure driven secondary flows, which evolve into a large pair of counter-rotating vortices. These vortices convect the low momentum fluid of the boundary layer towards the center of the duct, degrading both the uniformity and magnitude of the total pressure profile.

Wellborn, Steven R.↗
NASA NTRS1999

Condition Monitoring of Large-Scale Facilities

This document provides a summary of the research conducted for the NASA Ames Research Center under grant NAG2-1182 (Condition-Based Monitoring of Large-Scale Facilities). The information includes copies of view graphs presented at NASA Ames in the final Workshop (held during December of 1998), as well as a copy of a technical report provided to the COTR (Dr. Anne Patterson-Hine) subsequent to the workshop. The material describes the experimental design, collection of data, and analysis results associated with monitoring the health of large-scale facilities. In addition to this material, a copy of the Pennsylvania State University Applied Research Laboratory data fusion visual programming tool kit was also provided to NASA Ames researchers.

Hall, David L.↗
NASA NTRS2003

The Fluids Integrated Rack and Light Microscopy Module Integrated Capabilities

The Fluids Integrated Rack (FIR), a facility class payload, and the Light Microscopy Module (LMM), a subrack payload, are scheduled to be launched in 2005. The LMM integrated into the FIR will provide a unique platform for conducting fluids and biological experiments on ISS. The FIR is a modular, multi-user scientific research facility that will fly in the U.S. laboratory module, Destiny, of the International Space Station (ISS). The first payload in the FIR will be the Light Microscopy Module (LMM). The LMM is planned as a remotely controllable, automated, on-orbit microscope subrack facility, allowing flexible scheduling and control of fluids and biology experiments within the FIR. Key diagnostic capabilities for meeting science requirements include video microscopy to observe microscopic phenomena and dynamic interactions, interferometry to make thin film measurements with nanometer resolution, laser tweezers for particle manipulation, confocal microscopy to provide enhanced three-dimensional visualization of structures, and spectrophotometry to measure photonic properties of materials. The LMM also provides experiment sample containment for frangibles and fluids. This paper will provide a description of the current FIR and LMM designs, planned capabilities and key features. In addition a brief description of the initial five experiments planned for LMM/FIR will be provided.

Motil, Susan M.↗
NASA NTRS2004

The Use of SolidEdge as an Engineering Tool to Support NASA Projects

This presentation will cover the use of SolidEdge to facilitate creation of components and component assemblies generated by SOMTC in the support of NASA projects and GSE (e.g., Return To Flight and support components related to a multitude of optical assemblies.) Return To Flight (RTF) Program consist of several projects derived from a Columbia Accident Investigation Board (CAIB) report. One of the recommendations is to increase visual analysis capabilities of the flight vehicle prior to reaching orbit. SolidEdge as the primary 3-D modeler will be utilized by Space Optics Manufacturing Technology Center (SOMTC) at MSFC to generate multiple preliminary design concepts relative to air and ground based viewing platforms with increased fidelity.

Thornton, Gary↗
NASA NTRS2005

Optimal Configuration of Human Motion Tracking Systems: A Systems Engineering Approach

Human motion tracking systems represent a crucial technology in the area of modeling and simulation. These systems, which allow engineers to capture human motion for study or replication in virtual environments, have broad applications in several research disciplines including human engineering, robotics, and psychology. These systems are based on several sensing paradigms, including electro-magnetic, infrared, and visual recognition. Each of these paradigms requires specialized environments and hardware configurations to optimize performance of the human motion tracking system. Ideally, these systems are used in a laboratory or other facility that was designed to accommodate the particular sensing technology. For example, electromagnetic systems are highly vulnerable to interference from metallic objects, and should be used in a specialized lab free of metal components.

Henderson, Steve↗
NASA NTRS2008

Ambiguous Tilt and Translation Motion Cues in Astronauts after Space Flight

Adaptive changes during space flight in how the brain integrates vestibular cues with visual, proprioceptive, and somatosensory information can lead to impaired movement coordination, vertigo, spatial disorientation, and perceptual illusions following transitions between gravity levels. This joint ESA-NASA pre- and post-flight experiment is designed to examine both the physiological basis and operational implications for disorientation and tilt-translation disturbances in astronauts following short-duration space flights. The first specific aim is to examine the effects of stimulus frequency on adaptive changes in eye movements and motion perception during independent tilt and translation motion profiles. Roll motion is provided by a variable radius centrifuge. Pitch motion is provided by NASA's Tilt-Translation Sled in which the resultant gravitoinertial vector remains aligned with the body longitudinal axis during tilt motion (referred to as the Z-axis gravitoinertial or ZAG paradigm). We hypothesize that the adaptation of otolith-mediated responses to these stimuli will have specific frequency characteristics, being greatest in the mid-frequency range where there is a crossover of tilt and translation. The second specific aim is to employ a closed-loop nulling task in which subjects are tasked to use a joystick to null-out tilt motion disturbances on these two devices. The stimuli consist of random steps or sum-of-sinusoids stimuli, including the ZAG profiles on the Tilt-Translation Sled. We hypothesize that the ability to control tilt orientation will be compromised following space flight, with increased control errors corresponding to changes in self-motion perception. The third specific aim is to evaluate how sensory substitution aids can be used to improve manual control performance. During the closed-loop nulling task on both devices, small tactors placed around the torso vibrate according to the actual body tilt angle relative to gravity. We hypothesize that performance on the closed-loop tilt control task will be improved with this tactile display feedback of tilt orientation. The current plans include testing on eight crewmembers following Space Shuttle missions or short stay onboard the International Space Station. Measurements are obtained pre-flight at L-120 (plus or minus 30), L-90 (plus or minus 30), and L-30, (plus or minus 10) days and post-flight at R+0, R+1, R+2 or 3, R+4 or 5, and R+8 days. Pre-and post-flight testing (from R+1 on) is performed in the Neuroscience Laboratory at the NASA Johnson Space Center on both the Tilt-Translation Device and a variable radius centrifuge. A second variable radius centrifuge, provided by DLR for another joint ESA-NASA project, has been installed at the Baseline Data Collection Facility at Kennedy Space Center to collect data immediately after landing. ZAG was initiated with STS-122/1E and the first post-flight testing will take place after STS-123/1JA landing.

Clement, G.↗
NASA NTRS2019

Planetary Rover Simulation for Lunar Exploration Missions

When planning planetary rover missions it is useful to develop intuition and skills driving in, quite literally, alien environments before incurring the cost of reaching said locales. Simulators make it possible to operate in environments that have the physical characteristics of target locations without the expense and overhead of extensive physical tests. To that end, NASA Ames and Open Robotics collaborated on a Lunar rover driving simulator based on the open source Gazebo simulation platform and leveraging ROS (Robotic Operating System) components. The simulator was integrated with research and mission software for rover driving, system monitoring, and science instrument simulation to constitute an end-to-end Lunar mission simulation capability. Although we expect our simulator to be applicable to arbitrary Lunar regions, we designed to a reference mission of prospecting in polar regions. The harsh lighting and low illumination angles at the Lunar poles combine with the unique reflectance properties of Lunar regolith to present a challenging visual environment for both human and computer perception. Our simulator placed an emphasis on high fidelity visual simulation in order to produce synthetic imagery suitable for evaluating human rover drivers with navigation tasks, as well as providing test data for computer vision software development.In this paper, we describe the software used to construct the simulated Lunar environment and the components of the driving simulation. Our synthetic terrain generation software artificially increases the resolution of Lunar digital elevation maps by fractal synthesis and inserts craters and rocks based on Lunar size-frequency distribution models. We describe the necessary enhancements to import large scale, high resolution terrains into Gazebo, as well as our approach to modeling the visual environment of the Lunar surface. An overview of the mission software system is provided, along with how ROS was used to emulate flight software components that had not been developed yet. Finally, we discuss the effect of using the high-fidelity synthetic Lunar images for visual odometry. We also characterize the wheel slip model, and find some inconsistencies in the produced wheel slip behaviour.

Allan, Mark↗
NASA NTRS1995

Visualization of International Solar-Terrestrial Physics Program (ISTP) data

The International Solar-Terrestrial Physics Program (ISTP) is a multispacecraft, multinational program whose objective is to promote further understanding of the Earth's complex plasma environment. Extensive data sharing and data analysis will be needed to ensure the success of the overall ISTP program. For this reason, there has been a special emphasis on data standards throughout ISTP. One of the key tools will be the common data format (CDF), developed, maintained, and evolved at the National Space Science Data Center (NSSDC), with the set of ISTP implementation guidelines specially designed for space physics data sets by the Space Physics Data Facility (associated with the NSSDC). The ISTP guidelines were developed to facilitate searching, plotting, merging, and subsetting of data sets. We focus here on the plotting application. A prototype software package was developed to plot key parameter (KP) data from the ISTP program at the Science Planning and Operations Facility (SPOF). The ISTP Key Parameter Visualization Tool is based on the Interactive Data Language (IDL) and is keyed to the ISTP guidelines, reading data stored in CDF. With the combination of CDF, the ISTP guidelines, and the visualization software, we can look forward to easier and more effective data sharing and use among ISTP scientists.

Kessel, Ramona L.↗