Static balance is the reduction or elimination of the actuating effort in quasi-static motion of a mechanical system by adding non-dissipative force interactions to the system. In recent years, there is increasing recognition that static balancing of elastic forces in compliant mechanisms leads to increased efficiency as well as good force feedback characteristics. The development of insightful and pragmatic design methods for statically balanced compliant mechanisms is the motivation for this work. In our approach, we focus on a class of compliant mechanisms that can be approximated as spring-loaded rigid-link mechanisms. Instead of developing static balancing techniques directly for the compliant mechanisms, we seek analytical balancing techniques for the simplified spring–loaded rigid–link approximations. Towards that, we first provide new static balancing techniques for a spring-loaded four-bar linkage. We also find relations between static balancing parameters of the cognates of a four-bar linkage. Later, we develop a new perfect static balancing method for a general n-degree-of-freedom revolute and spherical jointed rigid-body linkages. This general method distinguishes itself from the known techniques in the following respects: 1 It adds only springs and not any auxiliary bodies. 2 It is applicable to linkage shaving any number of links connected in any manner. 3 It is applicable to both constant(i.e., gravity type) and linear spring loads. 4 It works both in planar and spatial cases. This analytical method is applied on the approximated compliant mechanisms as well. Expectedly, the compliant mechanisms would only be approximately balanced. We study the effectiveness of this approximate balance through simulations and a prototype. The analytical static balancing technique for rigid-body linkages and the study of its application to approximated compliant mechanisms are among the main contributions of this thesis.

Bei Compliantmechanismen ergibt sich die Bewegungsfreiheit durch die elastische Verformung nachgiebiger Elemente. Durch deren Formgebung und Werkstoffauswahl kann das Verformungsbild unter definierter Belastung theoretisch gezielt eingestellt werden. Die Nachgiebigkeit eines einzelnen Mechanismenelements kann dabei über seine gesamte Länge gleichmäßig verteilt oder aber auf einen bestimmten Bereich konzentriert sein. Ein besonderer Vorteil nachgiebiger Elemente ist dabei die Reduktion der Einzelteile und die hiermit verbundene Verringerung der Systemmasse, des Montageaufwands und der Montagekosten. Für den Einsatz im Maschinenbau wird in auch die Möglichkeit einer spielfreien und somit sehr exakten Führung der Bewegung genannt. Zudem ist es durch die Einsparung reibungsbehafteter Berührungselemente bzw. beweglicher Lagerungen möglich, den Verschleiß innerhalb des Mechanismus zu reduzieren. Somit vereinfacht sich auch die Wartung, was den Einsatz von Compliantmechanismen beispielsweise bei schwerer Zugänglichkeit besonders vorteilhaft erscheinen lässt. Eine Herausforderung bei der Entwicklung von Nachgiebigkeitsmechanismen ist die hinreichend genaue Beschreibung des Verformungsverhaltens ihrer nachgiebigen Glieder. Vereinfachte Modellansätze im Sinne der Biegebalken-Theorie 1. Ordnung sind hier nicht geeignet, die großen Verformungen analytisch zu erfassen. Zwar finden sich heute zahlreiche höherwertige Lösungen zur Theorie 2. und 3. Ordnung in einer fast unüberschaubaren Vielzahl von Publikationen – beispielgebend sei genannt – die verallgemeinert auf Grundlagenarbeiten fußen. Die analytische Beschreibung eines Biegebalkens bei großer Verformung ist jedoch noch immer eine komplexe Aufgabe, die ein hohes Maß an mathematischen Fähigkeiten vom praxisorientierten Ingenieur erfordert. Nur die präzise Beschreibung der nachgiebigen Mechanismenelemente eröffnet aber den Weg für eine Genaulagen-Synthese und somit letztlich den breiten Einsatz von nachgiebigen Elementen in Leichtbau-Mechanismen. Für eine effiziente Synthese sind daher alternative Lösungsansätze notwendig, die dem Ingenieur eine schnelle und hinreichend genaue Vorhersage des komplexen Verformungsverhaltens erlauben. Im Rahmen der Arbeit werden hierfür zunächst die erarbeiteten, neuartigen Methoden des SFB 639 in kompakter Form aufbereitet. Für die Mehrzahl der technischen Probleme soll hierauf aufbauend eine praxisgerechte Methode erarbeitet werden, die es erlaubt mit einfachen Mitteln eine Genaulagen-Synthese von Compliantmechanismen durchzuführen. Hierfür ist die Nachgiebigkeit (Kehrwert von Elastizitätsmodul × Flächenträgheitsmoment) so anzupassen, dass das veränderliche Schnittmoment entlang des Balkens zu einer stets gleichen Krümmung führt. Durch den Einsatz anisotroper Werkstoffe – wie etwa mehrschichtiger, textilverstärkter Faser-Kunststoff-Verbundwerkstoffe (FKV) – kann etwa, durch eine lokale Anpassung der Faserorientierung, der Elastizitätsmodul entlang des Mechanismenelementes gezielt eingestellt werden. Eine Veränderung der Nachgiebigkeit daher nicht nur geometrisch (Variation des Flächenträgheitsmoment) sondern auch werkstofflich induziert werden. Es entstehen Mechanismenelemente mit lokal angepasster Nachgiebigkeit, für die im Rahmen der Arbeit auch die Methoden zur gezielten Einstellung der veränderlichen Faserorientierung entlang der Balkenachse entwickelt werden.:1 Einleitung 1 1.1 Einführung in Nachgiebigkeitsmechanismen . . . . . . . . . . . . . . . . 2 1.2 Literaturschau . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.3 Problemstellung und Zielsetzung . . . . . . . . . . . . . . . . . . . . . . 6 2 Verformungsverhalten nachgiebiger Mechanismenelemente 8 2.1 Modellierung biegebeanspruchter brettförmiger Balken . . . . . . . . . 8 2.2 Betrachtungen zum Verformungsverhalten nachgiebiger Strukturen . . . 12 2.3 Krümmungsgleichung für die Analyse großer Verformungen . . . . . . . 15 2.4 Analyse von Compliantelementen mittels Phasenportrait-Methode . . . 18 3 Anpassung der lokalen Nachgiebigkeit 27 3.1 Erzeugung konstanter Krümmung . . . . . . . . . . . . . . . . . . . . . 27 3.2 Variation des Flächenträgheitsmomentes . . . . . . . . . . . . . . . . . 30 3.2.1 Modellanalyse mittels normierter Betrachtung . . . . . . . . . . 31 3.2.2 Technologische Umsetzung . . . . . . . . . . . . . . . . . . . . . 33 3.2.3 Experimentelle Validierung . . . . . . . . . . . . . . . . . . . . . 36 3.3 Variation des Elastizitätsmoduls . . . . . . . . . . . . . . . . . . . . . . 41 3.3.1 Anpassung durch lokale Variation der Faserorientierung . . . . . 42 3.3.2 Technologische Umsetzung . . . . . . . . . . . . . . . . . . . . . 51 3.3.3 Experimentelle Validierung . . . . . . . . . . . . . . . . . . . . . 57 4 Gezielte Synthese von Compliantmechanismen 67 4.1 Genaulagen-Synthese – Burmester-Theorie der bewegten Ebenen . . . . 68 4.1.1 Vorgabe von zwei Ebenenlagen . . . . . . . . . . . . . . . . . . 70 4.1.2 Vorgabe von drei und mehr Ebenenlagen . . . . . . . . . . . . . 73 4.2 Synthese von Mechanismen mit nachgiebigen Elementen . . . . . . . . 75 4.2.1 Polkongruente Synthese für zwei Ebenenlagen . . . . . . . . . . 75 4.2.2 Nicht-polkongruente Synthese für zwei Ebenenlagen . . . . . . . 77 4.2.3 Lösungsansatz zur Synthese von drei Ebenenlagen . . . . . . . . 80 4.3 Experimentelle Validierung . . . . . . . . . . . . . . . . . . . . . . . . . 81 5 Gestaltungshinweise für Compliantmechanismen 84 5.1 Freiheitsgrad von Mechanismen mit nachgiebigen Elementen . . . . . . 84 5.2 Langzeitverhalten von nachgiebigen Elementen . . . . . . . . . . . . . . 90 6 Zusammenfassung 94 Literaturverzeichnis 97 A Anhang 103 A.1 MATLAB R2016 Skript: Berechnung Phasenportrait . . . . . . . . . . 105 A.2 MATLAB R2016 Skript: Faserorientierung bei Vorgabe der Last . . . . 113 A.3 MATLAB R2016 Skript: Faserorientierung bei Vorgabe der Gliedlänge . 117

No description available.

Existing classes of centrifugal clutch concepts were reviewed. The pseudo-rigid-body model (PRBM), rigid-body replacement synthesis, force-deflection analysis, compliance potential evaluation, and compliant concept evaluation were used to develop effective new centrifugal clutch concepts. These methods helped develop and model four novel compliant centrifugal clutch designs, model two existing designs, and identify a concept with excellent potential for low-cost centrifugal clutch applications. This concept, the floating opposing arm (FOA) clutch, doubles the torque capacity metric relative to existing compliant designs. Torque and engagement speed models for this clutch were developed and verified against four prototype clutches. Additional novel designs devel-oped through this work have lower torque capacities, but also show good potential because of other unique characteristics. All of the designs were prototyped and tested to measure their torque-speed relationships.

No description available.

La grande majorité des robots actuels sont utilisés dans le domaine industriel. Ils doivent travailler à l’intérieur d’un environnement contrôlé afin de ne pas blesser les gens qui les entourent. Les robots industriels sont habituellement rigides et ne sont pas adaptés pour travailler dans des environnements non contrôlés. Afin de pallier à ce problème, une nouvelle branche de la robotique est en émergence. Qualifiée de robotique sécuritaire avec les humains, elle permet à des robots de travailler à proximité des humains et par le fait même, d’être utilisés dans plusieurs autres domaines dont l’environnement n’est pas contrôlé. L’utilisation d’actionneurs compliants est une approche utilisée pour la conception de robot souple. La majorité de ces types d’actionneurs possèdent une bande passante limitée en force ce qui est problématique pour plusieurs tâches nécessitant un contrôle à la fois précis en position et en force. Ce projet de maîtrise traite de l’élaboration et du contrôle d’un nouveau concept d’actionneur à grande densité de force utilisant la technologie magnétorhéologique (MR), et ce, dans un embrayage combiné à l’enroulement de tendons. Les embrayages MR permettent d’avoir de larges bandes passantes en force, d’isoler l’inertie du moteur avec le joint externe, de distribuer la puissance d’une seule source d’énergie cinétique et possède une grande densité de force. En combinant les embrayages MR à l’enroulement de tendons, il est possible de repousser la masse du robot à sa base, ce qui réduit grandement l’inertie de la structure du système. En utilisant le fluide MR dans un embrayage, le contrôle du couple est plus simple à implémenter. Par exemple, il est possible d’effectuer des mouvements qui requièrent beaucoup de force dans un court intervalle de temps, tout en étant capable d’effectuer une tâche qui requiert une grande précision de mouvement. Cette combinaison, inexistante actuellement, pourrait mener à des changements importants dans le secteur de la robotique sécuritaire avec les humains et de la robotique mobile. En plus de combiner ces dernières technologies mécaniques, les techniques de contrôle doivent être adaptées afin d’exploiter le plein potentiel de ce type de système. Dans ce mémoire, la conception et la réalisation de prototypes et de techniques de contrôle sont présentés. Pour valider les performances du nouveau type d’actionneur, les performances de bande passante en couple de l’embrayage MR et en force en ajoutant le système de transmission par câble sont illustrées et discutées. Par la suite, un prototype complet utilisant quatre embrayages MR est présenté et caractérisé au niveau de la bande passante en force et en position. En plus de l’aspect mécanique, une technique de contrôle adaptée au nouveau système d’actionnement est présentée. Pour valider et développer l’algorithme de contrôle en position, un prototype utilisant des moteurs électriques est développé. La capacité à s’adapter au changement de configuration du système d’actionneur est illustrée et discutée. Les algorithmes de contrôle sont ensuite validés sur le prototype utilisant les embrayages MR.

Mecanismos flexíveis são mecanismos onde o movimento é dado pela flexibilidade da estrutura ao invés da presença de juntas e pinos. Tem grande aplicação em dispositivos de mecânica de precisão, área biomédica, e mais recentemente na construção de microeletromecanismos (“MEMS" em inglês). Várias técnicas são usadas no projeto de mecanismos flexíveis, sendo que entre elas, a Otimização Topológica tem se mostrado a mais genérica e sistemática. O método de Otimização Topológica combina um método de otimização com o método dos elementos finitos (MEF). A utilização da Otimização Topológica permite que um engenheiro ou cientista projete o mecanismo para a sua aplicação específica sem precisar adquirir conhecimentos específicos sobre estruturas e mecanismos flexíveis. Dessa forma, o objetivo desse trabalho é aplicar o método de Otimização Topológica no projeto de mecanismos flexíveis, usando o modelo de material SIMP (método de densidades). O projeto é definido como sendo um problema de otimização de uma estrutura flexível, sujeito à restrição na quantidade de material, onde a função objetivo é maximizar o deslocamento numa dada região do domínio da estrutura quando submetida a um dado carregamento em outra região. Para ilustrar a implementação do método são apresentados resultados de topologias bidimensionais de mecanismos flexíveis. / Compliant Mechanisms consist of mechanisms where the movement is giving by the structural flexibility rather than the presence of joints and pins. They are applied to precision mechanic devices, biomedical field, and more recently to the design of microelectromechanical systems (MEMS). Many techniques has been applied to design compliant mechanisms. Among them, topology optimization method is a generic and systematic method. Topology optimization combines optimization algorithms with finite element method and allows an engineer or a scientist to design a compliant mechanism for its application without having to acquire specific knowledge about structures or compliant mechanisms. Therefore, the objective of this work is to apply topology optimization to design compliant mechanisms. The topology optimization method implemented is based on the SIMP material model. The design is defined as the optimization problem of a flexible structure, subject to an amount of material constraint, where the objective function is to maximize the output displacement in a certain region of the structure domain due to an applied load to other region. To illustrate the implementation of the method, two-dimensional topologies of compliant mechanisms are presented as a result.

Mecanismos flexíveis são mecanismos onde o movimento é dado pela flexibilidade da estrutura ao invés da presença de juntas e pinos. Tem grande aplicação em dispositivos de mecânica de precisão, área biomédica, e mais recentemente na construção de microeletromecanismos (“MEMS” em inglês). Várias técnicas são usadas no projeto de mecanismos flexíveis, sendo que entre elas, a Otimização Topológica tem se mostrado a mais genérica e sistemática. O método de Otimização Topológica combina um método de otimização com o método dos elementos finitos (MEF). A utilização da Otimização Topológica permite que um engenheiro ou cientista projete o mecanismo para a sua aplicação específica sem precisar adquirir conhecimentos específicos sobre estruturas e mecanismos flexíveis. Dessa forma, o objetivo desse trabalho é aplicar o método de Otimização Topológica no projeto de mecanismos flexíveis, usando o modelo de material SIMP (método de densidades). O projeto é definido como sendo um problema de otimização de uma estrutura flexível, sujeito à restrição na quantidade de material, onde a função objetivo é maximizar o deslocamento numa dada região do domínio da estrutura quando submetida a um dado carregamento em outra região. Para ilustrar a implementação do método são apresentados resultados de topologias bidimensionais de mecanismos flexíveis. / Compliant Mechanisms consist of mechanisms where the movement is giving by the structural flexibility rather than the presence of joints and pins. They are applied to precision mechanic devices, biomedical field, and more recently to the design of microelectromechanical systems (MEMS). Many techniques has been applied to design compliant mechanisms. Among them, topology optimization method is a generic and systematic method. Topology optimization combines optimization algorithms with finite element method and allows an engineer or a scientist to design a compliant mechanism for its application without having to acquire specific knowledge about structures or compliant mechanisms. Therefore, the objective of this work is to apply topology optimization to design compliant mechanisms. The topology optimization method implemented is based on the SIMP material model. The design is defined as the optimization problem of a flexible structure, subject to an amount of material constraint, where the objective function is to maximize the output displacement in a certain region of the structure domain due to an applied load to other region. To illustrate the implementation of the method, two-dimensional topologies of compliant mechanisms are presented as a result.

Origami-based design is increasing in popularity as its benefits and advantages become better understood and explored. However, many opportunities still exist for the application of origami principles to engineered designs, especially in the use of non-paper, thick sheet materials. One specific area utilizing thick sheet materials that is especially promising is origami-based mechanisms that require electrical power transfer applications. Many of these opportunities can be met by the use of surrogate folds. This thesis provides methods and frameworks that can be used by engineers to efficiently select and design surrogate folds for use in origami-based mechanisms and products. Surrogate folds are a means of achieving fold-like behavior, offering a simple method for achieving folding motions in thicker materials. A surrogate fold is a localized reduction in stiffness in a given direction allowing the material to function like a fold. A family of surrogate folds is reviewed, and the respective behaviors of the folds discussed. For a specified fold configuration, the material thickness is varied to yield different sizes of surrogate folds. Constraint assumptions drive the design, and the resultant configurations are compared for bending motions. Finite element and analytical models for the folds are also compared. Prototypes are made from different materials. This work creates a base for creating design guidelines for using surrogate folds in thick sheet materials. As mechanisms with origami-like movement increase in popularity, there is a need for conducting electrical power across folds. Surrogate folds can be used to address this need. Current methods and opportunities for conducting across folds are reviewed. A framework for designing conductive surrogate folds that can be adapted to fit specific applications is presented. Equations for calculating the electrical resistance in single surrogate folds as well as arrays are given. Prototypes of several conductive joints are presented and discussed. The framework is then followed in the design and manufacture of a conductive origami-inspired mechanism.

An investigation of IsoTruss structures in bending and torsion was conducted. A model was developed in ANSYS APDL where bay length and longitudinal member to helical member cross-sectional area ratio could be varied while holding the diameter constant. The model was validated using previously reported values from analytical models and empirical data. The model was used to make predictions of a specific geometry that was manufactured, tested and compared against the model. 12 specimens were built and tested. In flexure, empirical data had a percent error with respect to the model ranging from 10.9 to 65.4% with one outlier at 94.1%. In torsion, the empirical data had a percent error with respect to the model ranging from 0.4 to 34%. The test data exhibited similar trends compared to the model. An IsoTruss structure built to maximize torsional rigidity should have a diameter and bay length such that its helical angle is between 55 and 60 degrees. The inclusion of longitudinal members has a negligible impact on rigidity. Flexural rigidity is maximized with longitudinal members and with a minimal helical angle, placing helical members more in the direction of the longitudinal members. In order to minimize flexural rigidity, the longitudinal members should be removed from the design and the helical member angle should be maximized up to 80 degrees.