A System for Inertial Experiment Pointing and Attitude Control

A System for Inertial Experiment Pointing and Attitude Control

Author: Peter R. Kurzhals

Publisher:

Published: 1966

Total Pages: 76

ISBN-13:

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A system for inertial experiment pointing and attitude control (designated SIXPAC) of future manned spacecraft has been investigated. The SIXPAC concept consists of three double-gimbaled control moment gyros aligned with the axes of the spacecraft, and derives its control torques from precession of the gyro wheels. This system is readily mechanized, has inherent redundancy, and should provide a wider range of attitude control for manned spacecraft than the gyro systems previously considered. The SIXPAC can provide both the large range of control torques and the fine attitude holds associated with spacecraft experiments such as earth-surface tracking and mapping, photographic missions, and astronomical observations. Periodic aerodynamic and gravity-gradient torques can also be counteracted by the proposed system. Redundancies inherent to the three-gyro arrangement further allow reduced spacecraft control in case of failure or shutdown of one of the three gyros. The complete equations of motion for a spacecraft with the SIXPAC were developed, and were integrated numerically on a digital computer for an example mission with a possible Apollo applications concept. Results of this computer study were used to evaluate the spacecraft and control system response and to determine the power and fuel consumption of the SIXPAC. Characteristics time histories of the attitude and angular rates of the spacecraft are presented for a number of experiments that have been proposed for typical Apollo applications missions, and the performance of the gyro system is analyzed during the control tasks associated with these experiments.


Understanding and Managing Risk Attitude

Understanding and Managing Risk Attitude

Author: Dr David Hillson

Publisher: Gower Publishing, Ltd.

Published: 2012-03-01

Total Pages: 207

ISBN-13: 1409450503

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Despite many years of development, risk management remains problematic for the majority of organizations. One common challenge is the human dimension, in other words, the way people perceive risk and risk management. Risk management processes and techniques are operated by people, each of whom is a complex individual, influenced by many different factors. And the problem is compounded by the fact that most risk management involves people working in groups. This introduces further layers of complexity through relationships and group dynamics. David Hillson's and Ruth Murray-Webster's Understanding and Managing Risk Attitude will help you understand the human aspects of risk management and to manage proactively the influence of human behaviour on the risk process. The authors introduce a range of models, perspectives and examples to define and detail the range of possible risk attitudes; looking both at individuals and groups. Using leading-edge thinking on self-awareness and emotional literacy, they develop a powerful approach to address the most common shortfall in current risk management: the failure to manage the human aspects of the process. All this is presented in a practical and applied framework, rather than as a theoretical or academic treatise, based on the authors' shared experiences and expertise, rather than empirical research. Anyone involved in implementing risk management will benefit from this book, including risk practitioners, senior managers and directors responsible for corporate governance, project managers and their teams. It is also essential reading for HR professionals and others interested in organizational or behavioural psychology. This second edition is updated to strengthen the understanding of individual risk attitudes and reinforce what individuals can do to manage those risk attitudes that are leading them away from their objectives. For people who want to embrace this subject, the book highlights ways forward that are proven and practical.


Attitude Reacquisition of a Gravity-gradient Control-moment-gyro Stabilized Spacecraft

Attitude Reacquisition of a Gravity-gradient Control-moment-gyro Stabilized Spacecraft

Author: Clark E. Stohl

Publisher:

Published: 1970

Total Pages: 36

ISBN-13:

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Impulsive or time-decaying disturbances of sufficient magnitude will cause a gravitygradient control-moment-gyro stabilized spacecraft to tumble. A procedure for operating a thruster system by ground command to perform reacquisition was functionally designed and evaluated on an analog computer. When the disturbance has ceased, an on-board thruster system is used to aline the total angular momentum vector of the spacecraft in an orientation that allows the control-moment gyros to damp all spacecraft motion into a single axis. For a spacecraft in a Sun-synchronous orbit, a procedure was found to shorten the time for attitude reacquisition by using a solar array for crude attitude information.


Attitude Reports

Attitude Reports

Author: Thomas Grano

Publisher: Cambridge University Press

Published: 2021-06-03

Total Pages: 249

ISBN-13: 110853015X

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Propositional attitude reports are sentences built around clause-embedding psychological verbs, like Kim believes that it's raining or Kim wants it to rain. These interact in many intricate ways with a wide variety of semantically relevant grammatical phenomena, and represent one of the most important topics at the interface of linguistics and philosophy, as their study provides insight into foundational questions about meaning. This book provides a bird's-eye overview of the grammar of propositional attitude reports, synthesizing the key facts, theories, and open problems in their analysis. Couched in the theoretical framework of generative grammar and compositional truth-conditional semantics, it places emphasis on points of intersection between propositional attitude reports and other important topics in semantic and syntactic theory. With discussion points, suggestions for further reading and a useful guide to symbols and conventions, it will be welcomed by students and researchers wishing to explore this fertile area of study.