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At least 505 records · Page 28

University of Maryland walking robot: A design project for undergraduate students

The design and construction required that the walking robot machine be capable of completing a number of tasks including walking in a straight line, turning to change direction, and maneuvering over an obstable such as a set of stairs. The machine consists of two sets of four telescoping legs that alternately support the entire structure. A gear-box and crank-arm assembly is connected to the leg sets to provide the power required for the translational motion of the machine. By retracting all eight legs, the robot comes to rest on a central Bigfoot support. Turning is accomplished by rotating the machine about this support. The machine can be controlled by using either a user operated remote tether or the on-board computer for the execution of control commands. Absolute encoders are attached to all motors (leg, main drive, and Bigfoot) to provide the control computer with information regarding the status of the motors (up-down motion, forward or reverse rotation). Long and short range infrared sensors provide the computer with feedback information regarding the machine's relative position to a series of stripes and reflectors. These infrared sensors simulate how the robot might sense and gain information about the environment of Mars.

Olsen, Bob↗

Walking robot: A design project for undergraduate students

The design and construction of the University of Maryland walking machine was completed during the 1989 to 1990 academic year. It was required that the machine be capable of completing a number of tasks including walking a straight line, turning to change direction, and manuevering over an obstacle such as a set of stairs. The machine consists of two sets of four telescoping legs that alternately support the entire structure. A gear box and crank arm assembly is connected to the leg sets to provide the power required for the translational motion of the machine. By retracting all eight legs, the robot comes to rest on a central Bigfoot support. Turning is accomplished by rotating this machine about this support. The machine can be controlled by using either a user-operated remote tether or the onboard computer for the execution of control commands. Absolute encoders are attached to all motors to provide the control computer with information regarding the status of the motors. Long and short range infrared sensors provide the computer with feedback information regarding the machine's position relative to a series of stripes and reflectors. These infrared sensors simulate how the robot might sense and gain information about the environment of Mars.

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NASA/DOD Aerospace Knowledge Diffusion Research Project. Report 9: Summary report to phase 3 faculty and student respondents including frequency distributions

This project is designed to explore the diffusion of scientific and technical information (STI) throughout the aerospace industry. The increased international competition and cooperation in the industry promises to significantly affect the STI standards of U.S. aerospace engineers and scientists. Therefore, it is important to understand the aerospace knowledge diffusion process itself and its implications at the individual, organizational, national, and international levels. Examined here is the role of STI in the academic aerospace community.

Pinelli, Thomas E.↗

Walking robot: A design project for undergraduate students

The objective of the University of Maryland walking robot project was to design, analyze, assemble, and test an intelligent, mobile, and terrain-adaptive system. The robot incorporates existing technologies in novel ways. The legs emulate the walking path of a human by an innovative modification of a crank-and-rocker mechanism. The body consists of two tripod frames connected by a turning mechanism. The two sets of three legs are mounted so as to allow the robot to walk with stability in its own footsteps. The computer uses a modular hardware design and distributed processing. Dual-port RAM is used to allow communication between a supervisory personal computer and seven microcontrollers. The microcontrollers provide low-level control for the motors and relieve the processing burden on the PC.

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NASA Goddard Earth Sciences Graduate Student Program

The evolution of synoptic-scale dynamics associated with a middle and upper tropospheric cloud event that occurred on 26 November 1991 is examined. The case under consideration occurred during the FIRE CIRRUS-II Intensive Field Observing Period held in Coffeyville, KS during Nov. and Dec., 1991. Using data from the wind profiler demonstration network and a temporally and spatially augmented radiosonde array, emphasis is given to explaining the evolution of the kinematically-derived ageostrophic vertical circulations and correlating the circulation with the forcing of an extensively sampled cloud field. This is facilitated by decomposing the horizontal divergence into its component parts through a natural coordinate representation of the flow. Ageostrophic vertical circulations are inferred and compared to the circulation forcing arising from geostrophic confluence and shearing deformation derived from the Sawyer-Eliassen Equation. It is found that a thermodynamically indirect vertical circulation existed in association with a jet streak exit region. The circulation was displaced to the cyclonic side of the jet axis due to the orientation of the jet exit between a deepening diffluent trough and building ridge. The cloud line formed in the ascending branch of the vertical circulation with the most concentrated cloud development occurring in conjunction with the maximum large-scale vertical motion. The relationship between the large scale dynamics and the parameterization of middle and upper tropospheric clouds in large-scale models is discussed and an example of ice water contents derived from a parameterization forced by the diagnosed vertical motions and observed water vapor contents is presented.

Ackerman, Thomas P.↗

Research, planning, design and development of selected components, subsystems and systems for the Students for the Exploration and Development of Space Satellite (SEDSAT)

The work proposed in this task order was successfully accomplished. This is reflected in the approval by three NASA centers of the SEDSAT satellite to fly as a payload on the shuttle. All documentation necessary for evaluation of the satellite as a Shuttle payload was submitted and approved by the appropriate safety boards. The SEASIS instrument was demonstrated to work and its inclusion as a SEDSAT payload was accomplished in the task period. Finally, the SEDSAT interface to the NASA GSFC PES was approved by MSFC and GSFC with no substantive issues outstanding. As of the end of the contract date all milestones were met. However the NASA MSFC SEDS program was cancelled by the center. Since that time SEDSAT has gone on to be manifested on a Delta vehicle.

Wingo, Dennis↗

The First National Student Conference: NASA University Research Centers at Minority Institutions

The conference includes contributions from 13 minority universities with NASA University Research Centers. Topics discussed include: leadership, survival strategies, life support systems, food systems, simulated hypergravity, chromium diffusion doping, radiation effects on dc-dc converters, metal oxide glasses, crystal growth of Bil3, science and communication on wheels, semiconductor thin films, numerical solution of random algebraic equations, fuzzy logic control, spatial resolution of satellite images, programming language development, nitric oxide in the thermosphere and mesosphere, high performance polyimides, crossover control in genetic algorithms, hyperthermal ion scattering, etc.

Daso, Endwell O.↗

Structural Analysis of Components of the Students for the Exploration and Development of Space Satellite (SEDSAT) for the Small Expendable Deployer System (SEDS) Project Office

During the time frame allocated by the delivery order, members of the UAH Applied Research Program, with the cooperation of representatives from NASA investigated and conducted stress analysis of the SEDSAT1 satellite. The main area of concern was with the design of the deployable 10 m antennas. The placement of the holes for the antenna door hinge pin was too close to the edge of the antenna canister. Because of the load placed on the hinge pin, the stress analysis of this area suggested that more space would be needed between the holes and the edge of the material. Due to other conflicts, SEDSATI was removed from flying on the space shuttle and moved to the Delta Launch Vehicle. This changed many of the design requirements for the mounting and deployment of the satellite that forced a new design for the satellite. Once this happened, the stress analysis became obsolete, and the task was concluded.

Maddux, Gary A.↗

Student Support for Research in Hierarchical Control and Trajectory Planning

Generally, classical polynomial splines tend to exhibit unwanted undulations. In this work, we discuss a technique, based on control principles, for eliminating these undulations and increasing the smoothness properties of the spline interpolants. We give a generalization of the classical polynomial splines and show that this generalization is, in fact, a family of splines that covers the broad spectrum of polynomial, trigonometric and exponential splines. A particular element in this family is determined by the appropriate control data. It is shown that this technique is easy to implement. Several numerical and curve-fitting examples are given to illustrate the advantages of this technique over the classical approach. Finally, we discuss the convergence properties of the interpolant.

Martin, Clyde F.↗

Presentation to International Space University Students on g-LIMIT and STABLE-ATD Projects and Related Microgravity Vibration Isolation Topics

Vibration isolation is a necessity in the development of science in space and especially those experiments destined for operation on the International Space Station (ISS). The premise of microgravity scientific research is that in space, disturbances are minimized and experiments can be conducted in the absence of gravity. Although microgravity conditions exist in space, disturbances are still present in various forms and can be detrimental to the success of a microgravity experiment. Due to the plethora of disturbances and the various types that will occur on the space station, the microgravity community has elected to incorporate various means of isolating scientific payloads from these unwanted vibrations. Designing these vibration isolators is a crucial task to achieve true microgravity science. Since conventional methods of isolating payloads can achieve only limited isolation, new technologies are being developed to achieve the goal of designing a generic vibration isolation system. One such system being developed for the Microgravity Science Glovebox (MSG) is called g-LIMIT which stands for Glovebox Integrated Microgravity Isolation Technology. The g-LIMIT system is a miniaturized active vibration isolator for glovebox experiments. Although the system is initially developed for glovebox experiments, the g-LIMIT technology is designed to be upwardly scaleable to provide isolation for a broad range of users. The g-LIMIT system is scheduled to be flown on the UF-2 mission in August of the year 2000 and will be tested shortly thereafter. Once the system has been fully qualified, the hardware will become available for other researchers and will provide a platform upon which the goal of microgravity science can be achieved.

Alhorn, Dean↗

NASA Graduate Student Researchers Program (GSRP)

The primary area of research that Dr. Prinzel conducted was concerned with the effects of automation on the ability to perform various tasks which simulated those performed in an airplane cockpit. While automation is generally considered to be a positive addition to the cockpit, it also has some negative effects. The primary negative effect is related to the decrease in the number of tasks the pilot needs to perform. Having less to do can actually result in a decreased ability to be aware of and react to ongoing events, some of which may be critical to flight operations. The research was concerned with the ability of adaptive automation using psychophysiological measures, specifically brain waves (i.e. EEG), to control the degree to which tasks are automated as a function of the subject's level of alertness. Dr. Prinzel conducted and participated in the running of a number of experiments that examined adaptive automation in conjunction with the MultiAttribute Task Battery. Since there has been very little research conducted in this area, experiments needed to be conducted which established basic parameters for future research. The experiments that Dr. Prinzel was involved with examined the optimum number and location of electrode sites for recording EEG, the types of tasks which could readily be automated, the number of tasks which could be controlled by the adaptive automation system, and various EEG recording parameters which affect system functioning. A secondary area in which Dr. Prinzel conducted research concerned performance on vigiliance tasks. This research, while not initially directly related to adaptive automation, does have implication for such systems. Vigilance requires long term monitoring which often leads to the kind of negative effects seen when automation is introduced into a work environment. A third area of research in which Dr. Prinzel conducted research was concerned with gender differences in cognitive functioning and how that related to strategies for performing various tasks.

Freeman, Frederick G.↗

Graduate Student Researchers Program (GSRP)

An advanced concept in in-space transportation currently being studied is the Momentum-Exchange/Electrodynamic Reboost Tether System (MXER). The MXER system is a permanently orbiting platform designed to boost payloads from low earth orbit (LEO). Unlike conventional rockets that use propellants, MXER acts as a large momentum wheel, imparting a Av to a payload at the expense of its own orbital energy. After throwing a payload, the system reboosts itself using an electrodynamic tether to push against Earth s magnetic field and brings itself back up to an operational orbit to prepare for the next payload. The ability to reboost itself allows for continued reuse of the system without the expenditure of propellants. Considering the cost of lifting propellant from the ground to LEO to do the same Av boost at $10000 per pound, the system cuts the launch cost of the payload dramatically, and subsequently, the MXER system pays for itself after a small number of missions. As such, this technology is a valuable addition to NASA s mission for in-space transportation.

Westerhoff, John↗