Constraint Aware Behavior in Multi-Robot Systems

In this work we present a behavioral modeling framework that accounts for a battery constraint. This framework allows for a user to model robot teams of varying configuration performing com- mon robotic tasks such as exploration or going to user specified goals. The focus of this work is on how to model a constraint aware behavior and how assistance can be requested by and provided from a robot team. We show experimental results in simulated environments and identify trends that can be seen given a robot team configuration. We also discuss how this system can be adapted to different environments and different constraints. Our system can be setup to allow for differ- ent number of workers and helpers. The charging station, battery level and the behaviors of these agents can also be varied. We discuss the affect of these different policies on the performance of the workers. The performance is measured by the number of times the environment area is covered. In conclusion we would measure the performance based on the number of times the environment is covered by the agents

A Task Hand-Off Framework for Multi-Robot Systems

Multi-robot systems have many uses such as cleaning, exploration, search and rescue. These robots operate under constraints such as communication, battery etc. In this thesis, we provide a method by which the robots can hand-off their current task to a new robot so that the given task can be continued without interruption. It is assumed that the task can be handed off to any other robot without losing the progress on the task. In the task hand-off framework, the robots complete as much of the task as possible before trying to replenish their resources (e.g., refuel). The robots must also make sure that the task is handed over to another robot before they go back to refuel. We demonstrate the task hand-off framework in the context of a battery constraint. The robots hand-off their current task once they are low on battery. The robots are divided into helpers and workers. The workers are the ones that perform the given task while the helpers wait at charging locations. Once a worker determines it is running out of battery it calls for help and switches behaviors with a helper. The new worker then takes over the task. This framework allows a user to model robot teams performing common robotic tasks such as exploration, coverage or any other task where the task can be easily handed-off without losing any progress on the task. We also present a simple priority based inter-robot contention resolution algorithm using motion replanning to avoid inter-robot collisions. Each robot is assigned a priority. Whenever the robots are close to each other, the lower priority robots halt and the highest priority robot replans a path around the robots by considering them as additional robots. We demonstrate the task hand-off framework approach using a physics based simulator that is built on top of a physics engine and also using physical hardware. The physical hardware consists of multiple iRobot Create robots with an onboard ASUS Netbook. We provide results from room 407 of the Harvey Bum Bright Building at Texas A&M University. We show that the tasks get completed faster with task hand-off than when task hand-off was not allowed

On-orbit serviceability of space system architectures

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics; and, (S.M.)--Massachusetts Institute of Technology, Engineering Systems Division, Technology and Policy Program, 2006.Includes bibliographical references (p. 171-182).On-orbit servicing is the process of improving a space-based capability through a combination of in-orbit activities which may include inspection; rendezvous and docking; and value-added modifications to a satellite's position, orientation, and operational status. As a means to extend the useful life or operational flexibility of spacecraft, on-orbit servicing constitutes one pathway to a responsive space enterprise. Following launch, traditional satellite operations are tightly constrained by an inability to access the orbiting vehicle. With the exception of software upgrades from ground controllers, operators are wedded to supporting payload technologies that become rapidly obsolete and to bus structures that deform during the stress of launch and degrade in the harsh environment of space. On-orbit servicing offers satellite operators an option for maintaining or improving space-based capabilities without launching a new spacecraft. Numerous studies have been performed on on-orbit servicing, particularly regarding the architecture of the servicing provider. Several customer valuation case studies have also been performed to identify the economic case (or lack thereof) for different categories of servicing missions.(cont.) Little work, however, has been done to analyze the tradespace of potential on-orbit servicing customers-a global analysis of operational satellites currently orbiting the Earth. The goal of this research is to develop and test a methodology to assess the physical amenability of satellites currently in operation to on-orbit servicing. As defined here, physical amenability of a target satellite, or "serviceability," refers to the relative complexity required of a teleoperated or autonomously controlled robotic vehicle to accomplish on-orbit servicing. A three-step process is followed to perform serviceability assessments. First, a taxonomy of space systems is constructed to add structure to the problem and to identify satellite attributes that drive servicing mission complexity. Second, a methodology is proposed to assess serviceability across the four servicing activities of rendezvous, acquire, access, and service.(cont.) This includes development of an agent-based model based on orbital transfers as well as a generalized framework in which serviceability is decomposed into four elements: (1) knowledge, (2) scale, (3) precision, and (4) timing. Third, the value of architecture frameworks and systems engineering modeling languages for conducting serviceability assessments is explored through the development of a discrete event simulation of the Hubble Space Telescope. The thesis concludes with prescriptive technical considerations for designing serviceable satellites and a discussion of the political, legal, and financial challenges facing servicing providers.by Matthew G. Richards.S.M

Wings in Orbit: Scientific and Engineering Legacies of the Space Shuttle, 1971-2010

The Space Shuttle is an engineering marvel perhaps only exceeded by the station itself. The shuttle was based on the technology of the 1960s and early 1970s. It had to overcome significant challenges to make it reusable. Perhaps the greatest challenges were the main engines and the Thermal Protection System. The program has seen terrible tragedy in its 3 decades of operation, yet it has also seen marvelous success. One of the most notable successes is the Hubble Space Telescope, a program that would have been a failure without the shuttle's capability to rendezvous, capture, repair, as well as upgrade. Now Hubble is a shining example of success admired by people around the world. As the program comes to a close, it is important to capture the legacy of the shuttle for future generations. That is what "Wings In Orbit" does for space fans, students, engineers, and scientists. This book, written by the men and women who made the program possible, will serve as an excellent reference for building future space vehicles. We are proud to have played a small part in making it happen. Our journey to document the scientific and engineering accomplishments of this magnificent winged vehicle began with an audacious proposal: to capture the passion of those who devoted their energies to its success while answering the question "What are the most significant accomplishments?" of the longestoperating human spaceflight program in our nation s history. This is intended to be an honest, accurate, and easily understandable account of the research and innovation accomplished during the era

An Integrated Platform to Increase the Range/Endurance of Unmanned Helicopters

Class I (kg) autonomous helicopters are becoming increasingly popular for a wide range of non-military applications such as, surveillance, reconnaissance, traffic monitoring, emergency response, agricultural spraying, and many other eye in the sky missions. However, an efficient landing/takeoff platform with refueling/recharging capabilities has not yet been developed to increase the endurance and decrease the cost for Class I helicopters. This dissertation presents a three-prong approach for increasing the range and endurance of Class I autonomous helicopters, which will then spur demand by non-military organizations wanting to take advantage of such capabilities and, therefore, drop their price. The proposed Intelligent Self-Leveling and Nodal Docking System (ISLANDS) is developed as a mobile refueling/recharging station, which is one part of a three-pronged approach. ISLANDS is an electro-mechanical system that provides a safe landing surface for helicopters on gradients of up to 60%. ISLANDS operates off the grid and, therefore, must provide its own energy sources for the refueling/recharging tasks it performs. A method for determining ISLANDS\u27 energy needs for refueling/recharging of gas and/or electric helicopters for an arbitrary number of days is provided as the second part of the three-pronged approach. The final step for increasing autonomous helicopter endurance is a method for determining placement of ISLANDS nodes in the area to be serviced ensuring that the helicopters can achieve their mission goal. In this dissertation all aspects of the three-pronged approach are presented and explained in detail, providing experimental results that validate the proposed methods to solve each of the three problems. A case study using Commercially Off The Shelf (COTS) components that shows how all the parts of the proposed three-pronged solution work together for increasing the endurance of Class I helicopters is provided as a conclusion to the dissertation

Nuclear Propulsion Technical Interchange Meeting, volume 2

The purpose of the meeting was to review the work performed in fiscal year 1992 in the areas of nuclear thermal and nuclear electric propulsion technology development. These proceedings are an accumulation of the presentations provided at the meeting along with annotations provided by authors. The proceedings cover system concepts, technology development, and system modeling for nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP). The test facilities required for the development of the nuclear propulsion systems are also discussed

Space station systems: A bibliography with indexes (supplement 3)

This bibliography lists 780 reports, articles and other documents introduced into the NASA scientific and technical information system between January 1, 1986 and June 30, 1986. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite system. The coverage includes documents that define major systems and subsystems, servicing and support requirements, procedures and operations, and missions for the current and future space station

Marshall Space Flight Center Faculty Fellowship Program

The 2017 Marshall Faculty Fellowship Program involved 21 faculty in the laboratories and departments at Marshall Space Flight Center. These faculty engineers and scientists worked with NASA collaborators on NASA projects, bringing new perspectives and solutions to bear. This Technical Memorandum is a compilation of the research reports of the 2017 Marshall Faculty Fellowship program, along with the Program Announcement (Appendix A) and the Program Description (Appendix B). The research affected the following six areas: (1) Materials (2) Propulsion (3) Instrumentation (4) Spacecraft systems (5) Vehicle systems (6) Space science The materials investigations included composite structures, printing electronic circuits, degradation of materials by energetic particles, friction stir welding, Martian and Lunar regolith for in-situ construction, and polymers for additive manufacturing. Propulsion studies were completed on electric sails and low-power arcjets for use with green propellants. Instrumentation research involved heat pipes, neutrino detectors, and remote sensing. Spacecraft systems research was conducted on wireless technologies, layered pressure vessels, and two-phase flow. Vehicle systems studies were performed on life support-biofilm buildup and landing systems. In the space science area, the excitation of electromagnetic ion-cyclotron waves observed by the Magnetospheric Multiscale Mission provided insight regarding the propagation of these waves. Our goal is to continue the Marshall Faculty Fellowship Program funded by Center internal project offices. Faculty Fellows in this 2017 program represented the following minority-serving institutions: Alabama A&M University and Oglala Lakota College

Critical Issues in the History of Spaceflight

At a May 1981 "Proseminar in Space History"held at the Smithsonian Institution's National Air and Space Museum (NASM) in Washington, DC, historians came together to consider the state of the discipline of space history. It was an historic occasion. The community of scholars interested in the history of spaceflight was not large; previously, well-meaning but untrained aficionados consumed with artifacts had dominated the field, to the exclusion of the larger context. At a fundamental level, this proseminar represented a "declaration of independence" for what might be called the "new aerospace history." In retrospect, it may be interpreted as marking the rise of space history as a recognizable subdiscipline within the field of U.S. history. Bringing together a diverse collection of scholars to review the state of the art in space history, this proseminar helped in a fundamental manner to define the field and to chart a course for future research. Its participants set about the task of charting a course for collecting, preserving, and disseminating the history of space exploration within a larger context of space policy and technology. In large measure, the course charted by the participants in this 1981 proseminar aided in advancing a very successful agenda of historical research, writing, and understanding of space history. Not every research project has yielded acceptable results, nor can it be expected to do so, but the sum of the effort since 1981 has been impressive. The opportunities for both the exploration of space and for recording its history have been significant. Both endeavors are noble and aimed at the enhancement of humanity. Whither the history of spaceflight? Only time will tell. But there has been an emergent "new aerospace history" of which space history is a central part that moves beyond an overriding concern for the details of the artifact to emphasize the broader role of the spacecraft. More importantly, it emphasizes the whole technological system, including not just the vehicle but also the other components that make up the aerospace climate, as an integral part of the human experience. It suggests that many unanswered questions spur the development of flight and that inquisitive individuals seek to know that which they do not understand