Development and analysis of the Software Implemented Fault-Tolerance (SIFT) computer

SIFT (Software Implemented Fault Tolerance) is an experimental, fault-tolerant computer system designed to meet the extreme reliability requirements for safety-critical functions in advanced aircraft. Errors are masked by performing a majority voting operation over the results of identical computations, and faulty processors are removed from service by reassigning computations to the nonfaulty processors. This scheme has been implemented in a special architecture using a set of standard Bendix BDX930 processors, augmented by a special asynchronous-broadcast communication interface that provides direct, processor to processor communication among all processors. Fault isolation is accomplished in hardware; all other fault-tolerance functions, together with scheduling and synchronization are implemented exclusively by executive system software. The system reliability is predicted by a Markov model. Mathematical consistency of the system software with respect to the reliability model has been partially verified, using recently developed tools for machine-aided proof of program correctness

NASA Tech Briefs, June 1993

Topics include: Imaging Technology: Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Computer Programs; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences; Life Sciences

Industrial Robotics

This book covers a wide range of topics relating to advanced industrial robotics, sensors and automation technologies. Although being highly technical and complex in nature, the papers presented in this book represent some of the latest cutting edge technologies and advancements in industrial robotics technology. This book covers topics such as networking, properties of manipulators, forward and inverse robot arm kinematics, motion path-planning, machine vision and many other practical topics too numerous to list here. The authors and editor of this book wish to inspire people, especially young ones, to get involved with robotic and mechatronic engineering technology and to develop new and exciting practical applications, perhaps using the ideas and concepts presented herein

Characterization and analysis of an MRI compatible robot design for wrist psychophysics and rehabilitation

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (leaves 110-112).The MIT Wrist Robot has demonstrated the effectiveness of robotic therapy in aiding the rehabilitation of stroke victims. In order to investigate the neurological processes involved in this therapy and evaluate its effectiveness a patented MRI compatible version of the wrist robot is being developed, so that therapy and brain imaging may be carried out simultaneously. Patient actuation is accomplished with two standard electric motors, located outside the MRI chamber, which drive a non-ferrous, MRI compatible, low impedance hydraulic fluid transmission, consisting of two pairs of custom designed and fabricated vane motors. This thesis details the characterization and redesign of this robot, with emphasis placed upon the hydraulic system.Nevan Clancy Hanumara.S.M

Towards certifiable reconfigurable real-time mission critical software systems

This thesis makes a contribution towards the certification of reconfigurable real-time mission critical software systems. In highly reconfigurable software systems it is possible for a situation to arise where the system expends most or all of its resources on reconfiguring, and thus cannot provide sufficient resources to conduct intended computing functions. This anomaly has been termed "configuration thrashing" by the author due to its loose analogy to memory thrashing. If configuration thrashing is not eliminated, or at least minimised, then it is possible for circumstance to occur where reconfigurable systems cannot be certified due to potential failure to meet deadlines caused by configuration thrashing. The elimination of reconfiguration thrashing is a step towards certifiable dynamic reconfigurable systems capable of enforcing deadlines. The elimination of reconfiguration thrashing is necessary, though not sufficient, for this goal. In order to restrict configuration thrashing it is necessary to understand the possibilities available within reconfigurable software. A VDM-SL model is presented to explore the options available for reconfigurable architectures, and has allowed many operators to be formally specified providing a much greater understanding of the tasks involved in reconfiguration. The thesis demonstrates how model checkers can be used to check software processes for configuration thrashing using predefined CSP models, thus allowing system programmers to engineer configuration thrashing out of systems. However, model checkers are susceptible to state space explosion, particularly if models are large and / or complex, which may make the use of the model checkers impractical or even impossible for some systems. The thesis therefore also explores potential run-time solutions to configuration thrashing. These solutions allow developers to include additional logic / processes within their systems in order to eliminate configuration thrashing (without the use of model checkers). Several options are explored in-depth, from providing mechanisms for developers to choose when reconfiguration can / cannot occur, to a rule based solution. The exploration of the rule based solution explores issues such as rule expression, rule predictability, as well as potential core rules. The two approaches taken within this thesis to eliminate, or at least restrict sufficiently, configuration thrashing form a basis which would allow for the certification of reconfigurable real-time mission critical software systems.EThOS - Electronic Theses Online ServiceBAE SystemsGBUnited Kingdo