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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Localization Method for Remotely Operated Robot in Harsh Environments - 18561

For decommissioning of the Fukushima Daiichi Nuclear Power Station (FDNPS), the primary containment vessel (PCV) internal survey for fuel debris spreading has been needed. Remotely operated robots have been used for the survey. Localization of the robots during their operation is necessary to adjust sensor positions. However, it is difficult to calculate the robot position because the survey target areas have an unknown environment. In this research, we proposed a localization method which combines a stereo camera-based method for absolute localization and a periodic structure tracking method for relative localization for application to the unknown environment. The position accuracy for the proposed method was verified in a mock-up test, and we confirmed that the position accuracy satisfied the required accuracy of 30 mm. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2012

Application of Stereo Vision to the Reconnection Scaling Experiment

The measurement and simulation of the three-dimensional structure of magnetic reconnection in astrophysical and lab plasmas is a challenging problem. At Los Alamos National Laboratory we use the Reconnection Scaling Experiment (RSX) to model 3D magnetohydrodynamic (MHD) relaxation of plasma filled tubes. These magnetic flux tubes are called flux ropes. In RSX, the 3D structure of the flux ropes is explored with insertable probes. Stereo triangulation can be used to compute the 3D position of a probe from point correspondences in images from two calibrated cameras. While common applications of stereo triangulation include 3D scene reconstruction and robotics navigation, we will investigate the novel application of stereo triangulation in plasma physics to aid reconstruction of 3D data for RSX plasmas. Several challenges will be explored and addressed, such as minimizing 3D reconstruction errors in stereo camera systems and dealing with point correspondence problems.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Stereo photogrammetry reveals substantial drag on cloud thermals: STEREO PHOTOGRAMMETRY OF CLOUD THERMALS

Stereo photogrammetry, which uses two synchronized cameras to measure three-dimensional positions, is applied here to ascertain whether drag plays a role in the ascent of cloud thermals. In particular, stereo cameras are used to measure the sizes and speeds of cloud thermals in Florida. Using the vertical momentum equation, it is found that a substantial amount of drag (a drag coefficient on the order of 1) is needed to match both the stereo-photogrammetric data and the known buoyancy of clouds from previous in situ measurements and large-eddy simulations. Empirical data on form drag and theoretical calculations of wave drag reveal that, for the observed Froude numbers of cloud thermals, a drag coefficient of about one is to be expected.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS2012

Autonomous Rover Traverse and Precise Arm Placement on Remotely Designated Targets

This software controls a rover platform to traverse rocky terrain autonomously, plan paths, and avoid obstacles using its stereo hazard and navigation cameras. It does so while continuously tracking a target of interest selected from 10 20 m away. The rover drives and tracks the target until it reaches the vicinity of the target. The rover then positions itself to approach the target, deploys its robotic arm, and places the end effector instrument on the designated target to within 2-3-cm accuracy of the originally selected target. This software features continuous navigation in a fairly rocky field in an outdoor environment and the ability to enable the rover to avoid large rocks and traverse over smaller ones. Using point-and-click mouse commands, a scientist designates targets in the initial imagery acquired from the rover s mast cameras. The navigation software uses stereo imaging, traversability analysis, path planning, trajectory generation, and trajectory execution. It also includes visual target tracking of a designated target selected from 10 m away while continuously navigating the rocky terrain. Improvements in this design include steering while driving, which uses continuous curvature paths. There are also several improvements to the traversability analyzer, including improved data fusion of traversability maps that result from pose estimation uncertainties, dealing with boundary effects to enable tighter maneuvers, and handling a wider range of obstacles. This work advances what has been previously developed and integrated on the Mars Exploration Rovers by using algorithms that are capable of traversing more rock-dense terrains, enabling tight, thread-the-needle maneuvers. These algorithms were integrated on the newly refurbished Athena Mars research rover, and were fielded in the JPL Mars Yard. Forty-three runs were conducted with targets at distances ranging from 5 to 15 m, and a success rate of 93% was achieved for placement of the instrument within 2-3 cm of the target.

Nesnas, Issa A.↗
NASA NTRS1976

Stereo mapping with the Viking Lander camera imagery

Stereomapping techniques applicable to the processing of imagery from facsimile cameras on board the Viking Mars landing vehicles are discussed. Two methods of stereomapping are considered: use of a gnomonic projection to transform the digital imagery to an equivalent of a perspective projection by computerized rectification through image processing; and interfacing a high-speed digital computer to an analytical plotter so that rectification and corrections proceed in real time. Contour maps produced during tests of the Viking Lander cameras, as well as maps of the area surrounding the Viking Lander on the Martian surface, are presented.

Wu, S. S. C.↗
NASA NTRS1993

Monocular TV vs. Stereo TV for Solar Mazimum Satellite Repair Subtasks

Several operators performed two Solar Maximum Repair substask while viewing the workspace with either three monocular (non-stereo) black and white TV cameras or with one pair of stereo ablack and white TV cameras. For the monocular TV viewing, the three camera views were presented on three TV monitors, and a second operator controller the pan, tilt and zoom lens power of two of the cameras.

Satellite Repair↗
DOE OSTI2016

Determination of Cloud Base Height, Wind Velocity, and Short-Range Cloud Structure Using Multiple Sky Imagers Field Campaign Report

Clouds are a central focus of the U.S. Department of Energy (DOE)’s Atmospheric System Research (ASR) program and Atmospheric Radiation Measurement (ARM) Climate Research Facility, and more broadly are the subject of much investigation because of their important effects on atmospheric radiation and, through feedbacks, on climate sensitivity. Significant progress has been made by moving from a vertically pointing (“soda-straw”) to a three-dimensional (3D) view of clouds by investing in scanning cloud radars through the American Recovery and Reinvestment Act of 2009. Yet, because of the physical nature of radars, there are key gaps in ARM's cloud observational capabilities. For example, cloud radars often fail to detect small shallow cumulus and thin cirrus clouds that are nonetheless radiatively important. Furthermore, it takes five to twenty minutes for a cloud radar to complete a 3D volume scan and clouds can evolve substantially during this period. Ground-based stereo-imaging is a promising technique to complement existing ARM cloud observation capabilities. It enables the estimation of cloud coverage, height, horizontal motion, morphology, and spatial arrangement over an extended area of up to 30 by 30 km at refresh rates greater than 1 Hz (Peng et al. 2015). With fine spatial and temporal resolution of modern sky cameras, the stereo-imaging technique allows for the tracking of a small cumulus cloud or a thin cirrus cloud that cannot be detected by a cloud radar. With support from the DOE SunShot Initiative, the Principal Investigator (PI)’s team at Brookhaven National Laboratory (BNL) has developed some initial capability for cloud tracking using multiple distinctly located hemispheric cameras (Peng et al. 2015). To validate the ground-based cloud stereo-imaging technique, the cloud stereo-imaging field campaign was conducted at the ARM Facility’s Southern Great Plains (SGP) site in Oklahoma from July 15 to December 24. As shown in Figure 1, the cloud stereo-imaging system consisted of two inexpensive high-definition (HD) hemispheric cameras (each cost less than $1,500) and ARM’s Total Sky Imager (TSI). Together with other co-located ARM instrumentation, the campaign provides a promising opportunity to validate stereo-imaging-based cloud base height and, more importantly, to examine the feasibility of cloud thickness retrieval for low-view-angle clouds.

54 ENVIRONMENTAL SCIENCES↗
NASA NTRS1979

Study of a stereo electro-optical tracker system for the measurement of model deformations at the national transonic facility

An electro-optical method to measure the aeroelastic deformations of wind tunnel models is examined. The multitarget tracking performance of one of the two electronic cameras comprising the stereo pair is modeled and measured. The properties of the targets at the model, the camera optics, target illumination, number of targets, acquisition time, target velocities, and tracker performance are considered. The electronic camera system is shown to be capable of locating, measuring, and following the positions of 5 to 50 targets attached to the model at measuring rates up to 5000 targets per second.

Hertel, R. J.↗
DOE OSTI2019

A new method for increasing accuracy of distance measurement based on single visual camera

Camera has been widely used in computer vision and mobile robotics applications because the sensor provides complementary information. However, the chief drawback of camera is that it only can provide 2D image information without depth information. There are lots of people studying the distance measurement with single visual camera, however it is difficult to achieve high precision. Usually we use two cameras to form stereo image and measure distance. Obviously it is complex. In this paper, we study the reason why distance measurement with single camera can hardly achieve high precision and propose a new method for improving the accuracy. We evaluate the proposed method and compare with existing methods to demonstrate the efficiency and high precision.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1988

Stereo depth distortions in teleoperation

In teleoperation, a typical application of stereo vision is to view a work space located short distances (1 to 3m) in front of the cameras. The work presented here treats converged camera placement and studies the effects of intercamera distance, camera-to-object viewing distance, and focal length of the camera lenses on both stereo depth resolution and stereo depth distortion. While viewing the fronto-parallel plane 1.4 m in front of the cameras, depth errors are measured on the order of 2cm. A geometric analysis was made of the distortion of the fronto-parallel plane of divergence for stereo TV viewing. The results of the analysis were then verified experimentally. The objective was to determine the optimal camera configuration which gave high stereo depth resolution while minimizing stereo depth distortion. It is found that for converged cameras at a fixed camera-to-object viewing distance, larger intercamera distances allow higher depth resolutions, but cause greater depth distortions. Thus with larger intercamera distances, operators will make greater depth errors (because of the greater distortions), but will be more certain that they are not errors (because of the higher resolution).

Diner, Daniel B.↗
NASA NTRS1994

Development of an interchangeable end effector mechanism for the Ranger telerobotic vehicle

The Ranger program at the Space Systems Laboratory (SSL) at the University of Maryland is a demonstration of an extremely low cost, space flight experiment. The Ranger vehicle is designed to perform teleoperated spacecraft maintenance. Completing the various tasks included in spacecraft maintenance requires several specific tools. This paper describes the Ranger interchangeable end effector mechanism (IEEM). Its design allows Ranger to change end effectors to utilize the appropriate tool for the various tasks. The Ranger vehicle is designed with four manipulators. A seven degree-of-freedom (DOF) grappling manipulator securely attaches the vehicle to the work site. A 6 DOF camera positioning manipulator allows the operator to position a stereo pair of video cameras for visual feedback. The two remaining manipulators are the 7 DOF dexterous arms. They are the primary means by which Ranger accomplishes its required tasks. At the end of each of these dexterous manipulators is an IEEM. This paper begins with a brief overview of the Space Systems Laboratory and the Ranger program. The constraints leading to the requirements for an IEEM are described. The following section then describes the design strategies and the down selection process resulting in two candidate designs, taper and pneumatic connector type. Next, the leading candidate design is described in detail, followed by a preliminary discussion of failure modes and planned testing. The paper concludes with a brief review and a section discussing future work.

Cohen, Robert↗
NASA NTRS1977

Quasi-microscope concept for planetary missions

Viking lander cameras have returned stereo and multispectral views of the Martian surface with a resolution that approaches 2 mm/lp in the near field. A two-orders-of-magnitude increase in resolution could be obtained for collected surface samples by augmenting these cameras with auxiliary optics that would neither impose special camera design requirements nor limit the cameras field of view of the terrain. Quasi-microscope images would provide valuable data on the physical and chemical characteristics of planetary regoliths.

Huck, F. O.↗
NASA NTRS1991

Error analysis of combined stereo/optical-flow passive ranging

The motion of an imaging sensor causes each imaged point of the scene to correspondingly describe a time trajectory on the image plane. The trajectories of all imaged points are reminiscent of a flow (e.g., of liquid) which is the source of the term 'optical flow'. Optical-flow ranging is a method by which the stream of two-dimensional images obtained from a forward-looking forward-moving passive sensor is used to compute depth (or range) to points in the field of view. Another well-known ranging method consists of triangulation based on stereo images obtained from at least two stationary sensors. In this paper we analyze the potential accuracies of a combined optical flow and stereo passive-ranging system in the context of helicopter nap-of-the-earth obstacle avoidance. The Cramer-Rao lower bound is developed for the combined system under the assumption of an unknown angular bias error common to both cameras of a stereo pair. It is shown that the depth accuracy degradations caused by a bias error is negligible for a combined optical-flow and stereo system as compared to a monocular optical-flow system.

Barniv, Yair↗
NASA NTRS1992

Error Analysis of Combined Optical-Flow and Stereo Passive Ranging

The motion of an imaging sensor causes each imaged point of the seem to describe a time trajectory on the image plane. The trajectories of all imaged points are reminiscent of a flow (eg, of liquid) which is the source of the term "optical flow". Optical-flow ranging is a method by which the stream of two-dimensional images obtained from a forward-looking forward-moving passive sensor is used to compute range to points in the field of view. Another well-known ranging method consists of triangulation based on stereo images obtained from at least two stationary sensors. In this paper we analyze the potential accuracies of a combined optical flow and stereo passive-ranging system in the context of helicopter nap-of-the-earth obstacle avoidance. The Cramer-Rao lower bound (CRLB) is developed for the combined system under the assumption of a random angular misalignment common to both cameras of a stereo pair. It is shown that the range accuracy degradations caused by misalignment is negligible for a combined optical-flow and stereo system as compared with a monocular optical-flow system.

Barniv, Yair↗
DOE OSTI2018

Localized Imaging and Mapping for Underwater Fuel Storage Basins - 18364

Current methods for inspection of spent nuclear fuel storage basins involve lowering a single camera for visual inspection of walls and other structures. We present a localized inspection solution where the images are automatically annotated by localization information and a 3D model of the inspected area is generated. The system consists of an underwater sensor pod containing a stereo pair of cameras, light source, inertial measurement unit, and a pressure sensor. The sensors are time synchronized to provide precise measurements. We describe both the sensor pod and the algorithms that keep the pod localized. Preliminary results from in-air testing of a prototype are presented. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
NASA NTRS2011

Unmanned Ground Vehicle Perception Using Thermal Infrared Cameras

The ability to perform off-road autonomous navigation at any time of day or night is a requirement for some unmanned ground vehicle (UGV) programs. Because there are times when it is desirable for military UGVs to operate without emitting strong, detectable electromagnetic signals, a passive only terrain perception mode of operation is also often a requirement. Thermal infrared (TIR) cameras can be used to provide day and night passive terrain perception. TIR cameras have a detector sensitive to either mid-wave infrared (MWIR) radiation (3-5?m) or long-wave infrared (LWIR) radiation (8-12?m). With the recent emergence of high-quality uncooled LWIR cameras, TIR cameras have become viable passive perception options for some UGV programs. The Jet Propulsion Laboratory (JPL) has used a stereo pair of TIR cameras under several UGV programs to perform stereo ranging, terrain mapping, tree-trunk detection, pedestrian detection, negative obstacle detection, and water detection based on object reflections. In addition, we have evaluated stereo range data at a variety of UGV speeds, evaluated dual-band TIR classification of soil, vegetation, and rock terrain types, analyzed 24 hour water and 12 hour mud TIR imagery, and analyzed TIR imagery for hazard detection through smoke. Since TIR cameras do not currently provide the resolution available from megapixel color cameras, a UGV's daytime safe speed is often reduced when using TIR instead of color cameras. In this paper, we summarize the UGV terrain perception work JPL has performed with TIR cameras over the last decade and describe a calibration target developed by General Dynamics Robotic Systems (GDRS) for TIR cameras and other sensors.

terrain classification↗