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At least 613 records · Page 34

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NASA NTRS1983

Space station autonomy requirements

Several concepts of autonomy have emerged from space station technology and mission studies. Unifying these concepts is important to enabling the needs for and requirements of autonomous systems for a space station to be explored. One purpose of autonomy related to a space station is to offload routine, demonstrated, precisely specifiable tasks and functions from humans to machines in order to increase habitability, increase human-machine system productivity, or to decrease operational costs. Defining incremental roles, functions, and technical capabilities for autonomy leads to identification of computing systems technologies needed to enable various degrees of autonomy.

Anderson, J. L.↗

NASA NTRS1984

Transition and mixing in impulsively started jets and vortex rings

A new method is used to analyze transition in impulsively started jets and vortex rings. The method uses similarity variables to reduce the equations for unsteady particle paths to a quasi-autonomous system with the Reynolds number as a parameter. The flow pattern is represented in terms of the phase portrait of this system and the structure of the flow is defined by its critical points. Flow transition is examined in terms of bifurcations in the topology of the phase portrait which occur as the Reynolds number is increased. There is no assumption that the flow is parallel or that it is subjected to small disturbances. The method of analysis, through straightforward, is new and lies outside the usual small disturbance theory used to determine the stability of various profile shapes.

Cantwell, B. J.↗

NASA NTRS1986

Viscous starting jets

The transient motion which is produced when a viscous incompressible fluid is forced from an initial state of rest is studied. The equations for unsteady particle paths, written in terms of similarity variables, are analyzed as a quasi-autonomous system with the Reynolds number treated as a parameter. By finding and classifying critical points in the system's phase portrait, the flow structure is examined. It is shown that: (1) bifurcations in the phase portrait occur at specific values of the Reynolds number of the flow in question, and (2) the exact solutions of the Stokes equations for the low-Reynolds-number limit contain two critical Reynolds numbers and three distinct states of motion which culminate in the onset of a vortex roll-up.

Cantwell, Brian J.↗

NASA NTRS1987

Telerobotic controller development

To meet NASA's space station's needs and growth, a modular and generic approach to robotic control which provides near-term implementation with low development cost and capability for growth into more autonomous systems was developed. The method uses a vision based robotic controller and compliant hand integrated with the Remote Manipulator System arm on the Orbiter. A description of the hardware and its system integration is presented.

Otaguro, W. S.↗

NASA NTRS1988

Civil space technology initiative

Viewgraphs are presented on earth to orbit propulsion, booster technology, an aeroassist flight experiment, robotics, remote sensing of Earth, and autonomous systems.

Ambrus, Judith H.↗

NASA NTRS1988

Mars Rover Sample Return mission delivery and return challenges

The Mars Rover Sample Return mission is a robotic exploration mission culminating in the return of atmospheric and surface samples from Mars to Earth. To accomplish this complex mission requires sophisticated autonomous systems for many time-critical operations associated with the delivery and return phases, since the round trip light times preclude Earth-based control of these operations. In addition, there are significant engineering and technology challenges to be addressed to meet the mission science and exploration objectives.

Cohen, Aaron↗

NASA NTRS1990

Sparse distributed memory overview

The Sparse Distributed Memory (SDM) project is investigating the theory and applications of massively parallel computing architecture, called sparse distributed memory, that will support the storage and retrieval of sensory and motor patterns characteristic of autonomous systems. The immediate objectives of the project are centered in studies of the memory itself and in the use of the memory to solve problems in speech, vision, and robotics. Investigation of methods for encoding sensory data is an important part of the research. Examples of NASA missions that may benefit from this work are Space Station, planetary rovers, and solar exploration. Sparse distributed memory offers promising technology for systems that must learn through experience and be capable of adapting to new circumstances, and for operating any large complex system requiring automatic monitoring and control. Sparse distributed memory is a massively parallel architecture motivated by efforts to understand how the human brain works. Sparse distributed memory is an associative memory, able to retrieve information from cues that only partially match patterns stored in the memory. It is able to store long temporal sequences derived from the behavior of a complex system, such as progressive records of the system's sensory data and correlated records of the system's motor controls.

Raugh, Mike↗

NASA NTRS1990

Tele-Autonomous control involving contact

Object localization and its application in tele-autonomous systems are studied. Two object localization algorithms are presented together with the methods of extracting several important types of object features. The first algorithm is based on line-segment to line-segment matching. Line range sensors are used to extract line-segment features from an object. The extracted features are matched to corresponding model features to compute the location of the object. The inputs of the second algorithm are not limited only to the line features. Featured points (point to point matching) and featured unit direction vectors (vector to vector matching) can also be used as the inputs of the algorithm, and there is no upper limit on the number of the features inputed. The algorithm will allow the use of redundant features to find a better solution. The algorithm uses dual number quaternions to represent the position and orientation of an object and uses the least squares optimization method to find an optimal solution for the object's location. The advantage of using this representation is that the method solves for the location estimation by minimizing a single cost function associated with the sum of the orientation and position errors and thus has a better performance on the estimation, both in accuracy and speed, than that of other similar algorithms. The difficulties when the operator is controlling a remote robot to perform manipulation tasks are also discussed. The main problems facing the operator are time delays on the signal transmission and the uncertainties of the remote environment. How object localization techniques can be used together with other techniques such as predictor display and time desynchronization to help to overcome these difficulties are then discussed.

Shao, Lejun↗

NASA NTRS1991

Control of nausea and autonomic dysfunction with terfenadine, a peripherally acting antihistamine

Terfenadine (Seldane) was admisistered to 14 male subjects in a randomized, double-blinded, and cross-over design to assess the efficacy of this peripherally active antihistamine as an antimotion sickness drug. Terfenadine possesses practically no central side effects. A staircase profile test was administered 4 h following placebo or a single oral dose of terfenadine (300 mg). The study revealed a statistically significant therapeutic effect from terfenadine (p less than 0.05). This led to a conclusion that, because the drug does not or only poorly crosses the blood-brain barrier, a selective peripheral antihistamine action may be sufficient in the control of motion sickness induced through cross-coupled accelerative semicircular canal stimulation using a rotating chair. This finding implies that other peripherally acting agents might be found that possess even greater antimotion sickness efficacy. The present research raises additional questions regarding current theories on the etiology of motion sickness, its associated autonomic system dysfunction, and the validity of assumptions that effective pharmacological agents must act centrally.

Kohl, Randall L.↗

NASA NTRS1992

Needs for supervised space robots in space exploration

The areas of application for space robots in the Space Exploration Initiative (SEI) are examined by reviewing the roles of SEI supervised robots particularly with planet-surface systems (PSSs). Treatment is given to both teleoperated conventional robot systems and autonomous intelligent systems for comparison in terms of safety, reliability, and productivity. Two development stages are proposed including one with a robotic actor, human observer, and a human supervisor and a second in which a closed-loop control and monitoring system is established. The use of remote control is shown to require robustness, self-calibration and -diagnosis, adjustable autonomy, and multitask capability. The requirements of intelligent control are also listed so that the PSSs of the SEI can be used to enable surface exploration, local-resource utilization potential, and reductions of human tasks.

Erickson, Jon D.↗

NASA NTRS1993

Comparison Of Telerobot Control Modes

Report presents evaluation of three different modes of telerobot control: teleoperation with position control only; teleoperation with force reflection; and teleoperation with shared control, in which operator controls some elements of task while autonomous system controls other elements of task. Evaluation involved experiments in which nine trained operators used telerobot system to perform tasks of increasing difficulty - removal and insertion of electrical connector, removal and insertion of orbital replacement unit, and removal and insertion of electronic-circuit board in electronic chassis.

Zimmerman, Wayne F.↗

NASA NTRS1992

The planning coordinator: A design architecture for autonomous error recovery and on-line planning of intelligent tasks

Developing a robust, task level, error recovery and on-line planning architecture is an open research area. There is previously published work on both error recovery and on-line planning; however, none incorporates error recovery and on-line planning into one integrated platform. The integration of these two functionalities requires an architecture that possesses the following characteristics. The architecture must provide for the inclusion of new information without the destruction of existing information. The architecture must provide for the relating of pieces of information, old and new, to one another in a non-trivial rather than trivial manner (e.g., object one is related to object two under the following constraints, versus, yes, they are related; no, they are not related). Finally, the architecture must be not only a stand alone architecture, but also one that can be easily integrated as a supplement to some existing architecture. This thesis proposal addresses architectural development. Its intent is to integrate error recovery and on-line planning onto a single, integrated, multi-processor platform. This intelligent x-autonomous platform, called the Planning Coordinator, will be used initially to supplement existing x-autonomous systems and eventually replace them.

Farah, Jeffrey J.↗

NASA NTRS1992

Beta-endorphin and arginine vasopressin following stressful sensory stimuli in man

This experimentation partially defines, for the first time, the response of beta-endorphin (ENDO) in man during tests designed to elicit nausea and motion sickness. These responses are similar to those associated with arginine vasopressin (AVP) and adreno-corticotropin (ACTH) to the extent that all hormones rise in response to motion sickness (p less than 0.003). Repeated exposure diminished motion-induced release of ENDO (p less than 0.005) and AVP (p less than 0.004) despite a three-fold increase in resistance to motion stimuli. Higher post-stress levels of AVP (p less than 0.04) and ACTH (p less than 0.02) were correlated with greater resistance to motion sickness. These data support the hypothesis that release of AVP is a significant link between stressful motion and motion-induced nausea and other autonomic system changes. Further, resistant individual apparently can tolerate higher peripheral levels of AVP before nausea results. Peripheral release of ENDO and ACTH may follow release of AVP; however, given the extensive and complex functional interactions that exist between AVP and the opiate systems, it is not yet possible to define a clear role for ENDO in the etiology of motion sickness.

Kohl, Randall L.↗

NASA NTRS1993

Actuator placement in prestressed adaptive trusses for vibration control

This paper describes the optimal location selection of actuators for vibration control in prestressed adaptive trusses. Since prestressed adaptive trusses are statically indeterminate, the actuators to be used for vibration control purposes must work against (1) existing static axial prestressing forces, (2) static axial forces caused by the actuation, and (3) dynamic axial forces caused by the motion of the mass. In statically determinate adaptive trusses (1) and (2) are non - existing. The actuator placement problem in statically indeterminate trusses is therefore governed by the actuation energy and the actuator strength requirements. Assuming output feedback type control of selected vibration modes in autonomous systems, a procedure is given for the placement of vibration controlling actuators in prestressed adaptive trusses.

Jalihal, P.↗

NASA NTRS1989

Dynamic bin packing problem

In a previous work we have defined a general architecture model for autonomous systems, which can be mapped easily to describe the functions of any automated system (SDAG-86-01). In this note, we use the model to describe the problem of thermal management in space stations. First we briefly review the architecture, then we present the environment of our application, and finally we detail the specific function for each functional block of the architecture for that environment.

Dikshit, Piyush↗

NASA NTRS1992

View generated database

This document represents the final report for the View Generated Database (VGD) project, NAS7-1066. It documents the work done on the project up to the point at which all project work was terminated due to lack of project funds. The VGD was to provide the capability to accurately represent any real-world object or scene as a computer model. Such models include both an accurate spatial/geometric representation of surfaces of the object or scene, as well as any surface detail present on the object. Applications of such models are numerous, including acquisition and maintenance of work models for tele-autonomous systems, generation of accurate 3-D geometric/photometric models for various 3-D vision systems, and graphical models for realistic rendering of 3-D scenes via computer graphics.

Downward, James G.↗

NASA NTRS1994

Research on an autonomous vision-guided helicopter

Integration of computer vision with on-board sensors to autonomously fly helicopters was researched. The key components developed were custom designed vision processing hardware and an indoor testbed. The custom designed hardware provided flexible integration of on-board sensors with real-time image processing resulting in a significant improvement in vision-based state estimation. The indoor testbed provided convenient calibrated experimentation in constructing real autonomous systems.

Amidi, Omead↗

NASA NTRS1994

Active vision in satellite scene analysis

In earth observation or planetary exploration it is necessary to have more and, more autonomous systems, able to adapt to unpredictable situations. This imposes the use, in artificial systems, of new concepts in cognition, based on the fact that perception should not be separated from recognition and decision making levels. This means that low level signal processing (perception level) should interact with symbolic and high level processing (decision level). This paper is going to describe the new concept of active vision, implemented in Distributed Artificial Intelligence by Dassault Aviation following a 'structuralist' principle. An application to spatial image interpretation is given, oriented toward flexible robotics.

Naillon, Martine↗