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[en] MECHANISM DESIGN, KINEMATIC AND DYNAMIC ANALYSIS OF A ROBOTIC MANIPULATOR DRIVEN BY AN ACTIVE CARDAN JOINT WITH THREE DEGREES OF FREEDOM / [pt] PROJETO DE MECANISMO, ANÁLISE CINEMÁTICA E DINÂMICA DE UM MANIPULADOR ROBÓTICO ACIONADO POR JUNTA CARDÂNICA ATIVA COM TRÊS GRAUS DE LIBERDADEJEAN CARLO FERREIRA DE OLIVEIRA 24 September 2020 (has links)
[pt] O uso de juntas cardânicas ativas é restrito pela capacidade de torque de
pequenos motorredutores e, atualmente, os dispositivos embarcados são
obrigatórios para as aplicações robóticas. O controle dinâmico é essencial para
estudar as limitações desse dispositivo, portanto, o objetivo deste estudo foi
controlar a junta cardânica ativa de três graus de liberdade usando simulações
numéricas e experimento em bancada de testes. O manipulador foi projetado com
apenas uma junta cardânica para que a sua cinemática e dinâmica sejam exploradas;
por esse motivo, a junta foi construída com sensores de carga na base e sensor de
unidade de movimento inercial na parte superior do efetuador do manipulador.
Além disso, foram fabricadas três placas de controle: a primeira foi projetada para
controlar os três acionamentos dos motores de passo; a segunda, para ler o sensor
da unidade de movimento inercial; e a última, para ler os sensores de carga. Quatro
problemas foram descritos para testar os limites deste dispositivo, analisando, além
da cinemática e dinâmica, o atrito do rolamento, a identificação da folga e o torque
do impacto. O primeiro problema mantém a posição do efetuador do manipulador
constante enquanto transmite rotação entre os eixos. O segundo problema, o
efetuador recebe um caminho planejado, por exemplo, um círculo, mas não
transmite rotação entre os eixos. O terceiro problema é a combinação dos
movimentos anteriores, em que o efetuador transmite rotação entre os eixos,
enquanto segue por um caminho planejado. Para o quarto problema: uma nova
abordagem é aplicada para mover o efetuador de um ponto para outro usando
rotação cônica. / [en] The use of active cardan joints is restricted by torque capacity of small
motors, and currently embedded devices have been mandatory for robotic
applications. The dynamic control is essential to learn the limitations of this device,
thus the objective of this study is to control active cardan joints of three degrees of
freedom using numerical simulations and bench experiment. The manipulator was
designed with only one cardan joint to understand its kinematics and dynamics and,
for this reason, it was built with load sensors on its base and inertial motion unit
sensor at the top of the manipulator end-effector. Furthermore, three control boards
were manufactured: the first was designed to control the three stepper motor drives,
the second was designed to read the inertial motion unit sensor, and the last was
designed to read the load sensors. Four problems were described to test the limits
of this device, analysing not only the kinematics and dynamics, but also the bearing
friction, the backlash identification, and the impact torque. The first problem keeps
the position of the manipulator end-effector constant transmitting rotation between
the shafts. The second problem is given a planned path to the manipulator endeffector,
such as a circle, but it does not transmit rotation between the shafts. The
third problem is the combination of the previous motions, where the manipulator
end-effector applies the output spin, while it follows by a planned path. The fourth
problem, a new approach is applied to move the manipulator end-effector from one
point to another point using a conical rotation.
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The midlife crisis, gender, and social science in the United States, 1970-2000Schmidt, Susanne Antje January 2018 (has links)
This thesis provides the first rigorous history of the concept of midlife crisis. It highlights the close connections between understandings of the life course and social change. It reverses accounts of popularization by showing how an idea moved from the public sphere into academia. Above all, it uncovers the feminist origins of the concept and places this in a historically little-studied tradition of writing about middle age that rejected the gendered "double standard of aging." Constructions of middle age and life-planning were not always oppressive, but often used for feminist purposes. The idea of midlife crisis became popular in the United States with journalist Gail Sheehy's Passages (1976), a critique of Erik Erikson's male-centered model of ego development and psychoanalytic constructions of gender and identity more generally. Drawing on mid-century notions of middle life as the time of a woman's entry into the public sphere, Sheehy's midlife crisis defined the onset of middle age, for men and women, as the end of traditional gender roles. As dual-earner families replaced the male breadwinner model, Passages circulated widely, read by women and men of different generations, including social scientists. Three psychoanalytic experts-Daniel Levinson, George Vaillant, and Roger Gould-rebutted Sheehy by putting forward a male-only concept of midlife as the end of a man's family obligations; they banned women from reimagining their lives. Though this became the dominant meaning of midlife crisis, it was not universally accepted. Feminist scholars, most famously the psychologist and ethicist Carol Gilligan, drew on women's experiences to challenge the midlife crisis, turning it into a sign of emotional instability, immaturity, and egotism. Resonating with widespread understandings of mental health and social responsibility, and confirmed by large-scale surveys in the late 1990s, this relegated the midlife crisis to a chauvinist cliché. It has remained a contested concept for negotiating the balances between work and life, production and reproduction into the present day.
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Robustní řízení synchronního stroje s permanentními magnety a spínaným tokem / Fault-Tolerant Control of a Flux-switching Permanent Magnet Synchronous MachineAboelhassan, Mustafa Osman Elrayah January 2013 (has links)
Je jasné, že nejúspěšnější konstrukce zahrnuje postup vícefázového řízení, ve kterém každá fáze může být považována za samostatný modul. Provoz kterékoliv z jednotek musí mít minimální vliv na ostatní, a to tak, že v případě selhání jedné jednotky ostatní mohou být v provozu neovlivněny. Modulární řešení vyžaduje minimální elektrické, magnetické a tepelné ovlivnění mezi fázemi řízení (měniče). Synchronní stroje s pulzním tokem a permanentními magnety se jeví jako atraktivní typ stroje, jejíž přednostmi jsou vysoký kroutící moment, jednoduchá a robustní konstrukce rotoru a skutečnost, že permanentní magnety i cívky jsou umístěny společně na statoru. FS-PMSM jsou poměrně nové typy střídavého stroje stator-permanentní magnet, které představují významné přednosti na rozdíl od konvenčních rotorů - velký kroutící moment, vysoký točivý moment, v podstatě sinusové zpětné EMF křivky, zároveň kompaktní a robustní konstrukce díky umístění magnetů a vinutí kotvy na statoru. Srovnání výsledků mezi FS-PMSM a klasickými motory na povrchu upevněnými PM (SPM) se stejnými parametry ukazuje, že FS-PMSM vykazuje větší vzduchové mezery hustoty toku, vyšší točivý moment na ztráty v mědi, ale také vyšší pulzaci díky reluktančnímu momentu. Pro stroje buzené permanentními magnety se jedná o tradiční rozpor mezi požadavkem na vysoký kroutící moment pod základní rychlostí (oblast konstantního momentu) a provozem nad základní rychlostí (oblast konstantního výkonu), zejména pro aplikace v hybridních vozidlech. Je předložena nová topologie synchronního stroje s permanentními magnety a spínaným tokem odolného proti poruchám, která je schopná provozu během vinutí naprázdno a zkratovaného vinutí i poruchách měniče. Schéma je založeno na dvojitě vinutém motoru napájeném ze dvou oddělených vektorově řízených napěťových zdrojů. Vinutí jsou uspořádána takovým způsobem, aby tvořila dvě nezávislé a oddělené sady. Simulace a experimentální výzkum zpřesní výkon během obou scénářů jak za normálního provozu, tak za poruch včetně zkratových závad a ukáží robustnost pohonu za těchto podmínek. Tato práce byla publikována v deseti konferenčních příspěvcích, dvou časopisech a knižní kapitole, kde byly představeny jak topologie pohonu a aplikovaná řídící schémata, tak analýzy jeho schopnosti odolávat poruchám.
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