The Effects of End Termination on the Endurance Life of Twisted String Actuators PDF Download
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Author: Bradley Scott Roan
Publisher:
ISBN:
Category :
Languages : en
Pages : 92
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Book Description
Actuation is possibly the most fundamental aspect of any robotic system; a robot without any means to interact with the physical world is simply a computer. As such, new actuation methods are valuable additions to the field of robotics, and optimization of such methods can help advance the field as a whole. Twisted string actuators (TSA) are a relatively novel type of actuator, which convert the rotary motion of an electric motor to a tensile linear motion by twisting two or more strings around one another thereby shortening the length. When the twisting element is composed of high tensile strength fibers (such as high modulus polyethylene fiber), these actuators have the potential to possess many desirable characteristics of actuators, such as high force, high speed, high specific power (power to weight ratio), and high power density (power to volume ratio). Furthermore, because the transmission element is string, these actuators can be designed and built very cost efficiently. One of the major drawbacks of TSAs is their endurance life. While many engineering components operate in the millions of cycles, twisted string actuators operate in the range of tens of thousands of cycles. For some applications, this low endurance life is no issue, because the strings in the actuator are cheap and easily replaced. For many applications, however, this low of endurance life is unacceptable. The purpose of this thesis is to explore the effects of the end termination of the twisted element on the endurance life of the actuator. The basic architecture and concept of twisted string actuators is presented, as well as the mathematical description of their behavior. A hypothesis concerning the endurance life of the twisted element with respect to the end termination of the twisted element is presented and supported. A potential solution to the problem of low endurance life of twisted string actuators is presented and tested alongside two other common architectures. The results from this test are presented and discussed. When different architectures of twisted strings were tested and compared under identical conditions (i.e. style of string, material of string, resting length of twisting element, loading of the actuator, and actuation speed) it was found that the separator plate architecture outperformed both the pulley-to-pulley architecture, and the proposed architecture. The pulley-to-pulley tests resulted in a median endurance life of 36.5 cycles, the separator plate architecture resulted in a median endurance life of 364 cycles, and the proposed architecture resulted in a median endurance life of 115 cycles. During testing, the phenomenon of axial twist of individual strings, in addition to the twisting of the string pair driven by the motor, was observed, and identified as a potential explanation for the limited endurance life of the proposed architecture when compared with that of the separator plate architecture.
Author: Bradley Scott Roan
Publisher:
ISBN:
Category :
Languages : en
Pages : 92
Get Book Here
Book Description
Actuation is possibly the most fundamental aspect of any robotic system; a robot without any means to interact with the physical world is simply a computer. As such, new actuation methods are valuable additions to the field of robotics, and optimization of such methods can help advance the field as a whole. Twisted string actuators (TSA) are a relatively novel type of actuator, which convert the rotary motion of an electric motor to a tensile linear motion by twisting two or more strings around one another thereby shortening the length. When the twisting element is composed of high tensile strength fibers (such as high modulus polyethylene fiber), these actuators have the potential to possess many desirable characteristics of actuators, such as high force, high speed, high specific power (power to weight ratio), and high power density (power to volume ratio). Furthermore, because the transmission element is string, these actuators can be designed and built very cost efficiently. One of the major drawbacks of TSAs is their endurance life. While many engineering components operate in the millions of cycles, twisted string actuators operate in the range of tens of thousands of cycles. For some applications, this low endurance life is no issue, because the strings in the actuator are cheap and easily replaced. For many applications, however, this low of endurance life is unacceptable. The purpose of this thesis is to explore the effects of the end termination of the twisted element on the endurance life of the actuator. The basic architecture and concept of twisted string actuators is presented, as well as the mathematical description of their behavior. A hypothesis concerning the endurance life of the twisted element with respect to the end termination of the twisted element is presented and supported. A potential solution to the problem of low endurance life of twisted string actuators is presented and tested alongside two other common architectures. The results from this test are presented and discussed. When different architectures of twisted strings were tested and compared under identical conditions (i.e. style of string, material of string, resting length of twisting element, loading of the actuator, and actuation speed) it was found that the separator plate architecture outperformed both the pulley-to-pulley architecture, and the proposed architecture. The pulley-to-pulley tests resulted in a median endurance life of 36.5 cycles, the separator plate architecture resulted in a median endurance life of 364 cycles, and the proposed architecture resulted in a median endurance life of 115 cycles. During testing, the phenomenon of axial twist of individual strings, in addition to the twisting of the string pair driven by the motor, was observed, and identified as a potential explanation for the limited endurance life of the proposed architecture when compared with that of the separator plate architecture.
Author: Marc A. Meyers
Publisher:
ISBN: 9780511573422
Category : Strength of materials
Languages : en
Pages : 856
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Book Description
Includes numerous examples and problems for student practice, this textbook is ideal for courses on the mechanical behaviour of materials taught in departments of mechanical engineering and materials science.
Author: Phil M. Haun
Publisher: www.Militarybookshop.CompanyUK
ISBN: 9781780392769
Category : Transportation
Languages : en
Pages : 368
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Book Description
First published in 2003. The NATO-led Operation Allied Force was fought in 1999 to stop Serb atrocities against ethnic Albanians in Kosovo. This war, as noted by the distinguished military historian John Keegan, "marked a real turning point . . . and proved that a war can be won by airpower alone." Colonels Haave and Haun have organized firsthand accounts of some of the people who provided that airpower-the members of the 40th Expeditionary Operations Group. Their descriptions-a new wingman's first combat sortie, a support officer's view of a fighter squadron relocation during combat, and a Sandy's leadership in finding and rescuing a downed F-117 pilot-provide the reader with a legitimate insight into an air war at the tactical level and the airpower that helped convince the Serbian president, Slobodan Milosevic, to capitulate.
Author: Richard Shepherd Shevell
Publisher: Pearson Education India
ISBN: 9788177587425
Category : Aerodynamics
Languages : en
Pages : 468
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Book Description
Author: Jacob Fraden
Publisher: Springer Science & Business Media
ISBN: 0387216049
Category : Technology & Engineering
Languages : en
Pages : 596
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Book Description
Seven years have passed since the publication of the previous edition of this book. During that time, sensor technologies have made a remarkable leap forward. The sensitivity of the sensors became higher, the dimensions became smaller, the sel- tivity became better, and the prices became lower. What have not changed are the fundamental principles of the sensor design. They are still governed by the laws of Nature. Arguably one of the greatest geniuses who ever lived, Leonardo Da Vinci, had his own peculiar way of praying. He was saying, “Oh Lord, thanks for Thou do not violate your own laws. ” It is comforting indeed that the laws of Nature do not change as time goes by; it is just our appreciation of them that is being re?ned. Thus, this new edition examines the same good old laws of Nature that are employed in the designs of various sensors. This has not changed much since the previous edition. Yet, the sections that describe the practical designs are revised substantially. Recent ideas and developments have been added, and less important and nonessential designs were dropped. Probably the most dramatic recent progress in the sensor technologies relates to wide use of MEMS and MEOMS (micro-electro-mechanical systems and micro-electro-opto-mechanical systems). These are examined in this new edition with greater detail. This book is about devices commonly called sensors. The invention of a - croprocessor has brought highly sophisticated instruments into our everyday lives.
Author: United States. Department of the Army
Publisher:
ISBN:
Category : Automobiles
Languages : en
Pages : 68
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Book Description
Author: Barrie D. Dunn
Publisher: Springer
ISBN: 3319233629
Category : Technology & Engineering
Languages : en
Pages : 677
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Book Description
The objective of this book is to assist scientists and engineers select the ideal material or manufacturing process for particular applications; these could cover a wide range of fields, from light-weight structures to electronic hardware. The book will help in problem solving as it also presents more than 100 case studies and failure investigations from the space sector that can, by analogy, be applied to other industries. Difficult-to-find material data is included for reference. The sciences of metallic (primarily) and organic materials presented throughout the book demonstrate how they can be applied as an integral part of spacecraft product assurance schemes, which involve quality, material and processes evaluations, and the selection of mechanical and component parts. In this successor edition, which has been revised and updated, engineering problems associated with critical spacecraft hardware and the space environment are highlighted by over 500 illustrations including micrographs and fractographs. Space hardware captured by astronauts and returned to Earth from long durations in space are examined. Information detailed in the Handbook is applicable to general terrestrial applications including consumer electronics as well as high reliability systems associated with aeronautics, medical equipment and ground transportation. This Handbook is also directed to those involved in maximizing the relia bility of new materials and processes for space technology and space engineering. It will be invaluable to engineers concerned with the construction of advanced structures or mechanical and electronic sub-systems.
Author: Peter L. Conley
Publisher: John Wiley & Sons
ISBN: 9780471121411
Category : Technology & Engineering
Languages : en
Pages : 814
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Book Description
Die Entwicklung von Weltraumfahrzeugen ist ein Industriezweig, der in den vergangenen drei Jahrzehnten beständig gewachsen ist. Heute ist es eine komplexe technische, internationale Branche. Dieses Buch vermittelt Informationen über alle Mechanismen von Weltraumfahrzeugen. Spitzenexperten auf diesem Gebiet, die in verschiedenen Disziplinen zu Hause sind, haben einen wichtigen Beitrag hierzu geleistet. Das Buch ist in drei Teile untergliedert: Grundlagen und technische Eigenschaften wichtiger Materialien; Entwicklung und Verhalten kritischer Komponenten und eine Einführung in Fahrzeugniveau-Analysen und Integrationstechniken. (01/98)
Author: Vladimir M. Zatsiorsky
Publisher: Human Kinetics
ISBN: 1492582107
Category : Science
Languages : en
Pages : 571
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Book Description
Richly illustrated and presented in clear, concise language, Biomechanics of Skeletal Muscles is an essential resource for those seeking advanced knowledge of muscle biomechanics. Written by leading experts Vladimir Zatsiorsky and Boris Prilutsky, the text is one of the few to look at muscle biomechanics in its entirety—from muscle fibers to muscle coordination—making it a unique contribution to the field. Using a blend of experimental evidence and mechanical models, Biomechanics of Skeletal Muscles provides an explanation of whole muscle biomechanics at work in the body in motion. The book first addresses the mechanical behavior of single muscles—from the sarcomere level up to the entire muscle. The architecture of human muscle, the mechanical properties of tendons and passive muscles, the biomechanics of active muscles, and the force transmission and shock absorption aspects of muscle are explored in detail. Next, the various issues of muscle functioning during human motion are addressed. The transformation from muscle force to joint movements, two-joint muscle function, eccentric muscle action, and muscle coordination are analyzed. This advanced text assumes some knowledge of algebra and calculus; however, the emphasis is on understanding physical concepts. Higher-level computational descriptions are placed in special sections in the later chapters of the book, allowing those with a strong mathematical background to explore this material in more detail. Readers who choose to skip over these sections will find that the book still provides a strong conceptual understanding of advanced topics. Biomechanics of Skeletal Muscles also contains numerous special features that facilitate readers’ comprehension of the topics presented. More than 300 illustrations and accompanying explanations provide an extensive visual representation of muscle biomechanics. Refresher sidebars offer brief reminders of mathematical and biomechanical concepts, and From the Literature sidebars present practical examples that illustrate the concepts under discussion. Chapter summaries and review questions provide an opportunity for reflection and self-testing, and reference lists at the end of each chapter provide a starting point for further study. Biomechanics of Skeletal Muscles offers a thorough explanation of whole muscle biomechanics, bridging the gap between foundational biomechanics texts and scientific literature. With the information found in this text, readers can prepare themselves to better understand the latest in cutting-edge research. Biomechanics of Skeletal Muscles is the third volume in the Biomechanics of Human Motion series. Advanced readers in human movement science gain a comprehensive understanding of the biomechanics of human motion as presented by one of the world’s foremost researchers on the subject, Dr. Vladimir Zatsiorsky. The series begins with Kinematics of Human Motion, which details human body positioning and movement in three dimensions; continues with Kinetics of Human Motion, which examines the forces that create body motion and their effects; and concludes with Biomechanics of Skeletal Muscles, which explains the action of the biological motors that exert force and produce mechanical work during human movement.
Author: B. T. Fijalkowski
Publisher: Springer Science & Business Media
ISBN: 9400704097
Category : Technology & Engineering
Languages : en
Pages : 585
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Book Description
This book presents operational and practical issues of automotive mechatronics with special emphasis on the heterogeneous automotive vehicle systems approach, and is intended as a graduate text as well as a reference for scientists and engineers involved in the design of automotive mechatronic control systems. As the complexity of automotive vehicles increases, so does the dearth of high competence, multi-disciplined automotive scientists and engineers. This book provides a discussion into the type of mechatronic control systems found in modern vehicles and the skills required by automotive scientists and engineers working in this environment. Divided into two volumes and five parts, Automotive Mechatronics aims at improving automotive mechatronics education and emphasises the training of students’ experimental hands-on abilities, stimulating and promoting experience among high education institutes and produce more automotive mechatronics and automation engineers. The main subject that are treated are: VOLUME I: RBW or XBW unibody or chassis-motion mechatronic control hypersystems; DBW AWD propulsion mechatronic control systems; BBW AWB dispulsion mechatronic control systems; VOLUME II: SBW AWS diversion mechatronic control systems; ABW AWA suspension mechatronic control systems. This volume was developed for undergraduate and postgraduate students as well as for professionals involved in all disciplines related to the design or research and development of automotive vehicle dynamics, powertrains, brakes, steering, and shock absorbers (dampers). Basic knowledge of college mathematics, college physics, and knowledge of the functionality of automotive vehicle basic propulsion, dispulsion, conversion and suspension systems is required.
