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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Vridning av stabiliserande betongkärna med två hålrader : Utveckling av analytisk modell

Larsson, Aleksander, Larsson, Anton January 2016 (has links)
No description available.
2

TIP trajectory tracking of flexible-joint manipulators

Salmasi, Hamid 12 February 2010
In most robot applications, the control of the manipulators end-effector along a specified desired trajectory is the main concern. In these applications, the end-effector (tip) of the manipulator is required to follow a given trajectory. Several methods have been so far proposed for the motion control of robot manipulators. However, most of these control methods ignore either joint friction or joint elasticity which can be caused by the transmission systems (e.g. belts and gearboxes). This study aims at development of a comprehensive control strategy for the tip-trajectory tracking of flexible-joint robot manipulators. While the proposed control strategy takes into account the effect of the friction and the elasticity in the joints, it also provides a highly accurate motion for the manipulators end-effector. During this study several approaches have been developed, implemented and verified experimentally/numerically for the tip trajectory tracking of robot manipulators. To compensate for the elasticity of the joints two methods have been proposed; they are a composite controller whose design is based on the singular perturbation theory and integral manifold concept, and a swarm controller which is a novel biologically-inspired controller and its concept is inspired by the movement of real biological systems such as flocks of birds and schools of fishes. To compensate for the friction in the joints two new approaches have been also introduced. They are a composite compensation strategy which consists of the non-linear dynamic LuGre model and a Proportional-Derivative (PD) compensator, and a novel friction compensation method whose design is based on the Work-Energy principle. Each of these proposed controllers has some advantages and drawbacks, and hence, depending on the application of the robot manipulator, they can be employed. For instance, the Work-Energy method has a simpler form than the LuGre-PD compensator and can be easily implemented in industrial applications, yet it provides less accuracy in friction compensation. In addition to design and develop new controllers for flexible-joint manipulators, another contribution of this work lays in the experimental verification of the proposed control strategies. For this purpose, experimental setups of a two-rigid-link flexible-joint and a single-rigid-link flexible-joint manipulators have been employed. The proposed controllers have been experimentally tested for different trajectories, velocities and several flexibilities of the joints. This ensures that the controllers are able to perform effectively at different trajectories and speeds. Besides developing control strategies for the flexible-joint manipulators, dynamic modeling and vibration suppression of flexible-link manipulators are other parts of this study. To derive dynamic equations for the flexible-link flexible-joint manipulators, the Lagrange method is used. The simulation results from Lagrange method are then confirmed by the finite element analysis (FEA) for different trajectories. To suppress the vibration of flexible manipulators during the manoeuvre, a collocated sensor-actuator is utilized, and a proportional control method is employed to adjust the voltage applied to the piezoelectric actuator. Based on the controllability of the states and using FEA, the optimum location of the piezoelectric along the manipulator is found. The effect of the controllers gain and the delay between the input and output of the controller are also analyzed through a stability analysis.
3

TIP trajectory tracking of flexible-joint manipulators

Salmasi, Hamid 12 February 2010 (has links)
In most robot applications, the control of the manipulators end-effector along a specified desired trajectory is the main concern. In these applications, the end-effector (tip) of the manipulator is required to follow a given trajectory. Several methods have been so far proposed for the motion control of robot manipulators. However, most of these control methods ignore either joint friction or joint elasticity which can be caused by the transmission systems (e.g. belts and gearboxes). This study aims at development of a comprehensive control strategy for the tip-trajectory tracking of flexible-joint robot manipulators. While the proposed control strategy takes into account the effect of the friction and the elasticity in the joints, it also provides a highly accurate motion for the manipulators end-effector. During this study several approaches have been developed, implemented and verified experimentally/numerically for the tip trajectory tracking of robot manipulators. To compensate for the elasticity of the joints two methods have been proposed; they are a composite controller whose design is based on the singular perturbation theory and integral manifold concept, and a swarm controller which is a novel biologically-inspired controller and its concept is inspired by the movement of real biological systems such as flocks of birds and schools of fishes. To compensate for the friction in the joints two new approaches have been also introduced. They are a composite compensation strategy which consists of the non-linear dynamic LuGre model and a Proportional-Derivative (PD) compensator, and a novel friction compensation method whose design is based on the Work-Energy principle. Each of these proposed controllers has some advantages and drawbacks, and hence, depending on the application of the robot manipulator, they can be employed. For instance, the Work-Energy method has a simpler form than the LuGre-PD compensator and can be easily implemented in industrial applications, yet it provides less accuracy in friction compensation. In addition to design and develop new controllers for flexible-joint manipulators, another contribution of this work lays in the experimental verification of the proposed control strategies. For this purpose, experimental setups of a two-rigid-link flexible-joint and a single-rigid-link flexible-joint manipulators have been employed. The proposed controllers have been experimentally tested for different trajectories, velocities and several flexibilities of the joints. This ensures that the controllers are able to perform effectively at different trajectories and speeds. Besides developing control strategies for the flexible-joint manipulators, dynamic modeling and vibration suppression of flexible-link manipulators are other parts of this study. To derive dynamic equations for the flexible-link flexible-joint manipulators, the Lagrange method is used. The simulation results from Lagrange method are then confirmed by the finite element analysis (FEA) for different trajectories. To suppress the vibration of flexible manipulators during the manoeuvre, a collocated sensor-actuator is utilized, and a proportional control method is employed to adjust the voltage applied to the piezoelectric actuator. Based on the controllability of the states and using FEA, the optimum location of the piezoelectric along the manipulator is found. The effect of the controllers gain and the delay between the input and output of the controller are also analyzed through a stability analysis.
4

Körperbau, Gelenkbeweglichkeit und Handkräfte Erwachsener im Generationenvergleich / Body type, joint flexibility and hand forces of adults in generation comparism

Voigt, Andrea January 2008 (has links)
Die ergonomische Anpassung von Produkten der körpernahen Umwelt an den menschlichen Körper in seiner gesamten Variabilität erfordert anthropometrische Grundlagen. Die vorliegende Arbeit beschreibt und analysiert die Körpermasse, 17 Längenmaße, 5 Skelettrobustizitätsmaße, 6 Korpulenzmaße, 3 Kopfmaße, 5 Handmaße, 3 Fußmaße, sowie 10 Beweglichkeitsmaße der Wirbelsäule, 8 Beweglichkeitsmaße der Hand, 2 Beweglichkeitsmaße des Beines und 7 Handkräfte von 295 Probanden der drei Altersgruppen 20 bis 29 Jahre, 50 bis 59 Jahre und 60 bis 69 Jahre. Die Untersuchungen wurden im Zeitraum von September 2006 bis April 2007 durchgeführt. Ziel der Arbeit ist es, für den überwiegenden Teil der untersuchten körperlichen Merkmale erstmals für die deutsche Bevölkerung geschlechts- und altersspezifische Mittelwerte und Variabilitätsbereiche bis zum vollendeten 70. Lebensjahr zur Verfügung zu stellen. Das gilt insbesondere für die untersuchten Beweglichkeitsmaße und Handkräfte. Erstmals werden Korrelationen zwischen der Körperform, wie sie sich im Maßzusammenhang der unterschiedlichen Körperbautypen darstellt, der Gelenkbeweglichkeit und den Handkräften vorgestellt. Darüber hinaus wird durch den Vergleich der Ergebnisse der jungen und der beiden älteren Erwachsenengruppen untersucht, welche Unterschiede zwischen den verschiedenen Altersgruppen bestehen. Im Hinblick auf die zeitliche Gültigkeit der aktuellen Untersuchungsergebnisse werden der Einfluss des säkularen Trends und der Einfluss der ontogenetischen Alternsprozesse auf Längenmaße und Korpulenzmaße diskutiert. Die Arbeit zeigt auf, dass innerhalb der untersuchten Probanden eine große Variationsbreite in den Körpermaßen auftritt. Es lassen sich typische Altersunterschiede erkennen. Die Älteren sind im Mittel kleiner, weisen jedoch größere Skelettrobustizitäts- und Korpulenzmaße auf. Die dynamischen Maße weisen auf eine geringere Beweglichkeit der Wirbelsäule, teilweise auch der Hand hin. Die Handkräfte der Frauen werden mit zunehmendem Alter geringer, bei den Männern sind die Älteren kräftiger als die jungen Erwachsenen. Die Ergebnisse deuten auf einen gegenüber früheren Generationen verzögerten Beginn von körperlichen Alterserscheinungen hin, der im Hinblick auf die steigende Lebenserwartung der Bevölkerung eingehender untersucht werden sollte. / The ergonomic adaptation of products of the body close environment to the human body in its whole variability requires an anthropometric basis. The present work describes and analyses the body weight, 17 longitudinal, 5 skeletal and 6 corpulence dimensions of the human body, 3 head dimensions, 5 hand measurements, 3 foot measurements, as well as 10 measurements of the mobility of the spine, 8 mobility measurements of the hand, 2 mobility measurements of the leg and 7 hand forces of 295 test persons of the three age groups 20 to 29 years, 50 to 59 years and 60 to 69 years. The investigations were carried out in the period from September 2006 to April 2007 in Wolfsburg and Potsdam, Germany. The aim of the work is to make available averages and variability areas specific for age and specific for men and women up to the 70th birthday for the German population. This is valid in particular for the examined mobility measurements and hand forces. For the first time correlations are introduced between different body types and joint mobility and hand forces. In addition, it is examined by the comparison of the results of the young ones and both older adult's groups which differences exist between the examined age groups. With regard to the temporal validity of the investigation results the influence of the secular trend and the influence of the ontogenetic ageing processes on longitudinal and corpulence dimensions of the human body are discussed. The work indicates that within the examined test persons a big variation width appears in body measurements. Typical age differences exist. The older people are smaller on average, nevertheless, they show bigger skeletal and corpulence dimensions. The dynamic measurements point to a lower mobility of the spine, partially also of the hand. The hand forces of the women become lower with increasing age. In men the older test persons are stronger than the young adults. The results point to a delayed beginning of physical signs of ageing compared to former generations.
5

Reliability in measuring the range of motion of the aging cervical spine

Sinha, Juhi 05 April 2011 (has links)
The purposes of this study were to: 1) determine absolute intrarater reliability of using the cervical range of motion device (CROM) for measuring cervical movements in older adults, and 2) determine the intrarater reliability and concurrent validity of the Candrive protocol, which uses a universal goniometer to measure rotation. Forty older adults (75.7 + 4.7 years of age) were tested in two sessions, one week apart, by two raters. Intrarater reliability scores were good for the CROM protocol (coefficient of variation (CV) values were 5.5% and 6.2 % for cervical rotation). The Candrive protocol values were higher (CV = 7.9 and 9.4%). Concordance analyses suggested that the Candrive protocol was less than good in terms of its validity, particularly when order effects were taken into consideration. In conclusion, the CROM protocol demonstrated good reliability for either group or individual analyses, whereas the Candrive protocol was less reliable and its validity marginal.
6

Reliability in measuring the range of motion of the aging cervical spine

Sinha, Juhi 05 April 2011 (has links)
The purposes of this study were to: 1) determine absolute intrarater reliability of using the cervical range of motion device (CROM) for measuring cervical movements in older adults, and 2) determine the intrarater reliability and concurrent validity of the Candrive protocol, which uses a universal goniometer to measure rotation. Forty older adults (75.7 + 4.7 years of age) were tested in two sessions, one week apart, by two raters. Intrarater reliability scores were good for the CROM protocol (coefficient of variation (CV) values were 5.5% and 6.2 % for cervical rotation). The Candrive protocol values were higher (CV = 7.9 and 9.4%). Concordance analyses suggested that the Candrive protocol was less than good in terms of its validity, particularly when order effects were taken into consideration. In conclusion, the CROM protocol demonstrated good reliability for either group or individual analyses, whereas the Candrive protocol was less reliable and its validity marginal.
7

Vliv protahovacích cvičení typu strečink na rozsah kloubní pohyblivosti u studentů PF UJEP v Ústí nad Labem / The influence of stretching exercises on the range of joint flexibility in students PF UJEP in Ústí nad Labem

Kabešová, Hana January 2013 (has links)
THE INFLUENCE OF STRETCHING EXERCISES ON THE RANGE OF JOINT FLEXIBILITY IN STUDENTS AT JAN EVANGELISTA PURKYNĚ UNIVERSITY IN ÚSTÍ NAD LABEM The dissertation evaluates the influence of stretching exercises on the range of joint flexibility in students of the study programme Physical Education and Sport at Jan Evangelista Purkyně University in Ústí nad Labem. In total, 128 students aged 21 - 25 (78 women, 50 men) enrolled in the subject Basic Gymnastics took part in the experiment, conducted in the period from February to May of the academic year 2008/2009. Of these, 59 students were excluded by a physiotherapist - i.e. hypermobile men and hypermobile women as well as women with normal flexibility (excluded purposefully) subject to the results of the Thomayer test. In total, data from 39 men and 30 women were used. From April 2009, over a period of six weeks (before the end of the summer term tuition), an intervention flexibility programme including the Anderson static stretching method and the PNF stretching method by Sölveborn were applied for the research file. To evaluate the level of joint flexibility, the Sit and Reach Test and credit exercise to estimate joint flexibility were used. In a controlled interview, out-of-school activities were analysed, which contained stretching exercises with a...
8

Vliv protahovacích cvičení typu strečink na rozsah kloubní pohyblivosti u studentů PF UJEP v Ústí nad Labem / The influence of stretching exercises on the range of joint flexibility in students PF UJEP in Ústí nad Labem

Kabešová, Hana January 2013 (has links)
THE INFLUENCE OF STRETCHING EXERCISES ON THE RANGE OF JOINT FLEXIBILITY IN STUDENTS AT JAN EVANGELISTA PURKYNĚ UNIVERSITY IN ÚSTÍ NAD LABEM The dissertation evaluates the influence of stretching exercises on the range of joint flexibility in students of the study programme Physical Education and Sport at Jan Evangelista Purkyně University in Ústí nad Labem. In total, 128 students aged 21 - 25 (78 women, 50 men) enrolled in the subject Basic Gymnastics took part in the experiment, conducted in the period from February to May of the academic year 2008/2009. Of these, 59 students were excluded by a physiotherapist - i.e. hypermobile men and hypermobile women as well as women with normal flexibility (excluded purposefully) subject to the results of the Thomayer test. In total, data from 39 men and 30 women were used. From April 2009, over a period of six weeks (before the end of the summer term tuition), an intervention flexibility programme including the Anderson static stretching method and the PNF stretching method by Sölveborn were applied for the research file. To evaluate the level of joint flexibility, the Sit and Reach Test and credit exercise to estimate joint flexibility were used. In a controlled interview, out-of-school activities were analysed, which contained stretching exercises with a...
9

Effects of cracking of coupling beams onhigh rise towers subjected to wind load

Woldemikael, Brook Worku January 2020 (has links)
In high rise towers, reinforced concrete elevator shafts with coupling beams are extensively used as a principal structural element to resist lateral loads. The lateral load resistance of the tower is dominantly dependent on the stiffness of the load-bearing walls, and coupling beams connecting them. In an interest to study the reduction in the stiffness of high rise tower due to cracking in the coupling beams, variability in the reinforcement content, concrete grade and the effect of joint flexibility at the beam-wall intersection, this master thesis presents the analytical and finite element approaches to determine the equivalent height of the concrete coupling beams and the overall global stability of the high-rise tower. A comprehensive parametric study on 240 combinations of reinforced concrete coupling beams and 48 models of the global tower has been carried out to backtrack the effective stiffness of the RC coupling beams from the load-deflection curve. As a result, the stiffness and the equivalent height of coupling beams are computed and plotted as a function of the concretegrade, reinforcement content and aspect ratio. Additionally, the tip deflections of the towers for both the cracked & reinforced and un-reinforced & un-cracked models are also plotted as functions of the concrete grade, reinforcement content and aspect ratio.The obtained results show that the stiffness ratio and the ratio of the equivalent height to the normal height increase with the increase in the longitudinal reinforcement ratio and aspectratio but decrease with an increase in the concrete grade for both analytical and finite element methods. The tip deflection of tower is not significantly affected by an increase in the reinforcement content of slender coupling beams and vice versa for both the analytical and the finite element method. Independently of the slenderness of the composing coupling beams, the stiffness increases significantly with an increase in the concrete grade. These results show a good picture on how to choose the equivalent height in the model with no reinforcement. So, the developed diagram will be a more practical method for the designer of awhole building at the early stage design. Thick coupling beams need to be reinforced to reach the gross section’s stiffness while slender sections will have a higher stiffness with reinforcement. This would help the designer to find a more rational model without reinforcement. Using Hans Petersson’s analytical method, regarding the joint flexibility at the beam wall intersection, to exploit the full capacity of a concrete coupling beam section, the stiffness should be reduced. For global models, independently of the slenderness of the composing coupling beams, the stiffness increases significantly with an increase in the concrete grade. / I höghus används hisschakt av armerad betong tillsammans med kopplingsbalkar i stor utsträckning som främsta konstruktionselement för att motstå horisontella laster. Tornets horisontella bärförmåga är beroende av analytiska studier och studier med finita element metoden styvheten hos de bärande väggarna, och kopplingsbalkarna som förbinder dem. För att studera minskningen av styvheten i höghustorn på grund av sprickbildning i kopplingsbalkar, variationen i armeringsmängden, betongkvaliteten och effekten av ledflexibilitet vid balk-vägg-knutpunkten, presenterar detta examensarbete kopplingsbalkarnas effektiva styvhet och höghusets globala stabilitet. En omfattande parametrisk studie på 240 olika kombinationer av armerade kopplingsbalkar och 32 modeller av ett höghus har genomförts för att härleda den effektiva styvheten i de armerade kopplingsbalkarna från last-deformationskurvan. Som ett resultat beräknas styvheten och den ekvivalenta höjden av kopplingsbalkarna och plottas som funktion av betongkvaliteten och armeringsmängden. Dessutom modelleras höghuset för både spruckna & armerade kopplingsbalkar samt oarmerade & ospruckna kopplingsbalkar för att erhålla utböjningen av höghusets topp. Resultatet plottas som funktion av betongkvaliteten och armeringsmängden. De erhållna resultaten visar att styvhetsförhållandet och förhållandet mellan ekvivalent höjd till normal höjd ökar med mer längsgående armering och tvärsnittsförhållandet men minskar med en ökning av betongkvaliteten för både den analytiska och finita elementmetoden. Utböjningen av höghusets topp påverkas inte nämnbart av en ökning av armeringsmängden i de slanka kopplingsbalkarna och vice versa för både den analytiska och finita elementmetoden. Oberoende av slankheten av kopplingsbalkarna ökar styvheten betydligt med en ökning av betongkvaliteten. Dessa resultat visar en bra bild på hur man väljer ekvivalent höjd i modellen utan armering. Därmed kommer det framtagna diagrammet vara en mer praktisk metod för att i ett tidigt skede konstruera en hel byggnad. Tjocka kopplingsbalkar måste armeras för att nå tvärsnittets styvhet medan smala tvärsnitt kommer att ha en högre styvhet med armering. Detta skulle hjälpa konstruktören att hitta en mer rationell modell utan armering. Med hjälp av Hans Peterssons analytiska metod, angående ledflexibiliteten vid balk-väggknutpunkten, bör styvheten minskas för att utnyttja den fulla kapaciteten hos en betongkopplingsbalk. För globala modeller, oberoende av de slanka kopplingsbalkarna, ökar styvheten betydligt med en ökning av betongkvaliteten.

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