Η διπλωματική αυτή εργασία πραγματεύεται την προσομοίωση μιας ορθοπεδικής διάταξης οστεογένεσης, την τρισδιάστατη απεικόνιση αυτής από κατασκευαστικής άποψης καθώς και την πλήρη μελέτη της κίνησης αυτής με τον προγραμματισμό της ορθής και αντίστροφης κινηματικής. Πιο συγκεκριμένα η μελέτη που γίνεται αφορά το είδος πλατφόρμας Stewart και χρήση αυτής ως εξωτερικής συσκευής οστεογένεσης. Πρωτεύον μέλημά μας αποτελεί η περιγραφή του φαινομένου της οστεογένεσης και η κατανόηση της λειτουργίας και ανάπτυξης των οστών (Κεφάλαιο 2). Στη συνέχεια προβαίνουμε σε μια αναλυτική παρουσίαση των συσκευών οστεογένεσης που υπάρχουν στον χώρο με επιμέρους ανάλυση της λειτουργίας της κάθε μιας καταλήγοντας στην πλατφόρμα που θα μελετήσουμε (Κεφάλαιο 3). Ακολούθως, παρουσιάζουμε την κινηματική ανάλυση της πλατφόρμας Stewart τόσο την ορθή όσο και την ανάστροφη και επίσης γίνεται και μελέτη της δυναμικής ανάλυσης της διάταξης αυτής (Κεφάλαιο 4). Λαμβάνοντας υπόψη όλα τα προηγούμενα, είμαστε σε θέση να προχωρήσουμε στην προσομοίωση της πλατφόρμας Stewart , αρχίζοντας με τον προγραμματισμό των κινηματικών εξισώσεων, συνεχίζοντας με την προσομοίωση στο Simmechanics και τέλος δημιουργώντας την τρισδιάστατη απεικόνιση της διάταξης στο VRML toolbox του Matlab όπου φαίνεται η κίνηση της πλατφόρμας στον τρισδιάστατο χώρο (Κεφάλαιο 5). Τέλος, παρουσιάζονται τα συμπεράσματα και οι προοπτικές της εν λόγω εργασίας (Κεφάλαιο 6). / This thesis deals with the simulation of an orthopaedic device of osteogenesis, the 3d depiction concerning the constructional aspect as well as with the complete study of the movement with the planning of kinematics and inverse kinematics. More concretely the study concerns the category of a Stewart platform and the use of this platform as an exterior appliance for osteogenesis. Our first concern is the description of the phenomenon of osteogenesis and the comprehension of the operation and growth of bones (Chapter 2). Then we proceed in an analytic presentation of devices of osteogenesis that exist, with specific analysis of the operation of any kind that exists in the industrial field leading to the platform that we will study (Chapter 3). Following, we present the kinematical analysis of the Stewart platform as well as the study of the dynamic analysis of this fixator (Chapter 4). Taking into consideration all the above, we advance in the simulation of the Stewart platform, beginning with the planning of kinematical equations, continuing with the simulation in the Simmechanics and finally creating a 3d depiction of the device in the VRML toolbox of Matlab where we can watch the movement of the platform in the xyz space (Chapter 5). Finally, the conclusions and the prospects of this work are represented (Chapter 6).

No description available.

L'objectif de ce travail est de construire une machine d'essai pour la prothèse. La machine doit être capable de reproduire les mêmes conditions dynamiques et cinématiques appliquées sur la prothèse pendant l'utilisation normale.Le nombre d'amputation et les causes d'amputation ont été recueillis. Différents types de prothèses ont été classés selon la prothèse de jambe par hauteur d'amputation, prothèse passive et active, différenciées par la nature de leur actionneur. La plupart des machines d'essai pour la prothèse ont été étudiées à partir de la prospective technologique et capacitaire. Déterminer toutes les limitations de la plupart des machines d'essai existantes, et les besoins de développer une nouvelle machine pour remplir complètement ces besoins ont été développés.Ensuite, nous avons étudié et analysé la dynamique de la marche et de la course humaines. Les équations du mouvement en prenant en considération les masses et les moments d'inertie des segments squelettiques. La plupart des paramètres de la démarche ont été extraits. En conclusion, nous avons les exigences cinématiques du centre de gravité humain pour générer 6 DOF que la machine d'essai devrait effectuer pour imiter la démarche humaine normale et courir.Trois conceptions ont été proposées pour implanter la machine d'essai; Bras de robot articulé, manipulateur cartésien et Stewart Platform (SP). Après la mise en œuvre des trois solutions, nous avons trouvé la solution la plus appropriée est le SP attaché avec une hanche active artificielle. Nous avons choisi la puissance hydraulique car c'est la technique d'actionnement la plus appropriée pour notre solution, connaissant les forces d'actionnement requises.Pour aider à contrôler le mouvement de SP, une nouvelle solution de modèle géométrique direct pour la planeuse et la plate-forme Stewart 6-6 a été développée en utilisant les capteurs rotatifs au lieu de capteurs de revêtement comme voulu pour les actionneurs hydrauliques. L'analyse de sensibilité a été étudiée pour cette solution, et un calcul analytique pour le calcul de l'espace de travail a également été développé.La conclusion de cette machine d'essai est que nous pouvons créer toute la dynamique du corps humain, c'est-à-dire marcher ou courir ou monter et descendre des escaliers. La solution développée peut porter des procédures d'essai pour la prothèse passive ou active. / The objective of this work is to build a testing machine for prosthesis. The machine should be able to reproduce the same dynamic and kinematics conditions applied on the prosthesis during the normal use.Numbers of amputation, and causes of amputation were collected. Different types of prosthesis were classified according to the leg prosthesis per amputation height, passive and active prosthesis, differentiated by the nature of their actuator. Most of the testing machine for the prosthesis were studied form the technological and capability prospective. Determining all the limitations of most of existing testing machines, and the needs to develop a new machine to full fill these needs were developed.Then we studied and analyzed the dynamics of the human gait and run. The equations of motion by taking into consideration the masses and moments of inertia of skeletal segments. Most of the parameters of gait were extracted. In conclusion, we have the kinematic requirements of the human center of gravity to generate 6 DOF that the testing machine should carry out to emulate the normal human gait and run.Three designs were proposed to implement the testing machine; Articulated robot arm, Cartesian manipulator, and Stewart Platform (SP). After implementing the three solutions we found the most suitable solution is the SP attached with it an artificial active hip. We have chosen the hydraulic power as it is the most suitable actuation technique for our solution knowing the required actuation forces.To help in controlling the SP motion, a novel Closed-form solution of direct Geometric model for planer and 6-6 Stewart Platform using the rotary sensors instead of liner sensors as wanted to the hydraulic actuators was developed. Sensitivity analysis was studied for that solution, and analytical calculation for computing the workspace was also developed.The conclusion from this testing machine is that we can create all the dynamics of the human body, i.e. walking or running or going up and down stairs. The developed solution can carry testing procedures for either passive or active prothesis.

This paper presents the research and development of a 3-legged micro Parallel Kinematic Manipulator (PKM) for positioning in micro-machining and assembly operations. The structural characteristics associated with parallel manipulators are evaluated and the PKMs with translational and rotational movements are identified. Based on these identifications, a hybrid 3-UPU (Universal Joint-Prismatic Joint-Universal Joint) parallel manipulator is designed and fabricated. The principles of the operation and modeling of this micro PKM is largely similar to a normal size Stewart Platform (SP). A modular design methodology is introduced for the construction of this micro PKM. Calibration results of this hybrid 3-UPU PKM are discussed in this paper. / Singapore-MIT Alliance (SMA)

No description available.

No description available.

This body of work presents methods for the optimization, analysis, and control of mixed serial-parallel structures known as SP-Stacks. A SP-Stack is a series of Stewart Platforms (SPs) linked via their top and bottom plates to create a serial chain of parallel mechanisms. SP-Stacks are unique in their bridging of the benefits of parallel architectures (high rigidity, strength, and precision) and serial architectures (reach and manipulability), at the cost of being extremely overactuated. SP-Stacks are also difficult to provide kinematic solutions for, as neither forward nor inverse kinematics of a system are closed form. The first work presented focuses on presenting algorithms and optimization functions pertaining to the kinematic configuration of a SP-Stack. It first presents two methods of fast inverse kinematics (IK) for the SP-Stack which do not take forces into account. The outputs of those more simplistic solvers as used as initial conditions for a Nonlinear Program (NLP) algorithm which optimizes the internal configuration of a SP-Stack such that the end effector (EE) plate remains at the desired location, and the maximal force experienced on any actuator is minimized. The second work presented focuses on hardware testing some of the constituent algorithms and conclusions drawn from the first paper and determining methods of compensating for, in software, detected defects in hardware and hardware measurement systems. This work also demonstrates a different form of force-optimization - compliance control (CC), which is executed on both a single SP responding to external forces, and a 2 SP-Stack responding to regular internal perturbation. Conclusions drawn from these works are useful for stacks of an arbitrary number of SPs, can be extended to other mixed-kinematic systems, and advance the capabilities of these systems to be useful contributors in field robotics. / Master of Science / A stewart platform (SP) is a type of robot which consists of two plates interconnected by six linear actuators in parallel, which allow the robot to either translate or rotate about any axis in space. SPs are limited in their ability to move, as their parallel construction limits their workspace. In order to counteract this, SPs can be stacked on top of one another, creating a SP-Stack. The SP-Stack is capable of using its status as a mixed serial-parallel system to move in a significantly larger area (an advantage derived by the serial component of its architecture) and retain extraordinary rigidity and strength (an advantage from its parallel architecture). As each SP has 6 Degrees of Freedom (6DoF), enabling the previously described free-space motion, a SP-Stack possesses 6n DoF, making it overactuated. An overactuated system has multiple internal configurations which allow for a desired end effector configuration. The body of work presented herein focuses on manipulating the overactuation of SP-Stacks to achieve desirable results such as finding configurations which are most resistant to external loading (optimization of actuator forces) or algorithms which allow SP-Stacks to comply with external loading (compliance control (CC)). The first work presented herein focuses on determining an optimal configuration for a 4 SP-Stack such that the maximum force experienced by any one of its linear actuators is minimized, given a known external force. This work also presents two methods of generating initial configurations for the SP-Stack which are fed into the optimization algorithm which produces the final solution, as well as providing details on the constraints which govern the movement and validity of configurations for the system. The second work presented expands on the work done in the first, moving into hardware testing for verification of algorithms which calculate forces experienced by the linear actuators. The hardware testing showcases some errors that can be introduced by low fidelity hardware, along with methodologies for counteracting those errors. Finally, the second work introduces CC, the ability for a robot to move itself to adapt to incoming forces, and applies it to a physical 2 SP-Stack as a demonstrator.

The work performed in this thesis involves the study of human hip joint kinematics and load analysis. Such analyses are very useful for investigating mobility and natural functionality as well as the variation in motion due to replacement implants. The objective of this study is to design, build and testing of a universal human joint simulator that is configurable to hold several human joints and easily programmable to create the required motion. This was performed by creating a Stewart Platform, which is capable of moving in all six degrees of freedom; the maximum number needed by any human joint. Many specific human joint simulators are available on the market for simulating all major human limbs. These are used for wear testing replacement joints by using high load repetitive motion. These systems have a predetermined limit degree of movement and are very expensive; if one wanted to emulate another joint, one would have to purchase a whole new system. This novel system compromises of a three-phase power supply, Control Area Network with six actuators and drivers, a force reading clamp with strain gauges and data logger. A user friendly computer program was developed that is able to derive joint movement data from two inputs and replicating the movement by driving the platform, as well as recording force and displacement data from the joint. The product would be marketed towards biomechanical researchers and implant designers. Verification of this system was performed by simulating the human hip joint. A known combination of kinematic and force data were inputted into the system for nine different types of activities. The resultant force and joint centre displacement was then compared to see how well the system perform in comparison to the inputted data from a previous study. The outcome of this project is a fully functional machine and configurable program that can create movement data at varying speeds and body weights; which is also able to drive the human joint simulator. The design also costs a fraction of any industrial joint simulator. It is hoped that the simulator will allow easier study of both the kinematics and load analysis within the human joints, with the intent on aiding investigation into mobility and functionality; as well as variation in motion caused by a replacement implant.

In this work, we investigate the active vibration isolation and damping of sensitive equipment. Several single-axis isolation techniques are analyzed and tested. A comparison between the sky-hook damper, integral force feedback, inertial velocity feedback and LagLead control techniques is conducted using several practical examples. The study of single-axis systems has been developed and used to build a six-axis isolator. A six degrees of freedom active isolator based on Stewart platform has been designed manufactured and tested for the purpose of active vibration isolation of sensitive payloads in space applications. This six-axis hexapod is designed according to the cubic configuration; it consists of two triangular parallel plates connected to each other by six active legs orthogonal to each other; each leg consists of a voice coil actuator, a force sensor and two flexible joints. Two different control techniques have been tested to control this isolator : integral force feedback and Lag-Lead compensator, the two techniques are based on force feedback and are applied in a decentralized manner. A micro-gravity parabolic flight test has been clone to test the isolator in micro-gravity environment. ln the context of this research, another hexapod has been produced ; a generic active damping and precision painting interface based on Stewart platform. This hexapod consists of two parallel plates connected to each other by six active legs configured according to the cubic architecture. Each leg consists of an amplified piezoelectric actuator, a force sensor and two flexible joints. This Stewart platform is addressed to space applications where it aims at controlling the vibrations of space structures while connecting them rigidly. The control technique used here is the decentralized integral force feedback.

Předkládaná práce se zabývá návrhem modelu dynamiky paralelního manipulátoru optimálního pro účely návrhu řízení. Zvolený přístup je založen na modelování dynamiky systému v simulačním prostředí Matlab SimMechanics následovaném linearizací modelu. Výsledný stavový lineární model mimo jiné umožňuje snadné posouzení řiditelnosti a pozorovatelnosti modelu. Díky své relativní jednoduchosti je model také výpočetně nenáročný. Přístup je demonstrován na návrhu dvouvrstvého řízení SimMechanics modelu Stewartovy platformy, na kterém bylo následně navržené řízení úspěšně testováno. Podstatná část práce obsahuje přístup k modelování neurčitých parametrů dynamického modelu Stewartovy platformy a stejnosměrného motoru Maxon RE 35 a jeho výsledky. Předložený přístup je založen na modelování parametrické neurčitosti způsobem, kdy je neurčitost definována individuálně pro jednotlivé prvky stavových matic modelu. Samotná neurčitost je potom určena rozdílem mezi jednotlivými parametry příslušných matic nominálního modelu a modelu se stanovenou maximální neurčitostí parametrů. Výsledný neurčitostní model je vzhledem ke své stavové reprezentaci vhodný pro návrh regulátoru založeném na metodách návrhu robustního řízení, například minimalizaci normy H-nekonečno. Popsaná metoda byla použita pro kompenzaci posunu mezi pracovními body, okolo kterých je prováděna linearizace a pro kompenzaci nepřesnosti modelování vybraných parametrů modelů Stewartovy platformy a stejnosměrného motoru. Získané modely (v prostředí SimMechanics a neurčitostní model) byly experimentálně porovnány s chováním jednoho z lineárních pohonů Stewartovy platformy. Rozdíl v datech obdržených ze simulace v prostředí SimMechanics a naměřených na reálném stroji byl téměř kompletně pokryt neurčitostním modelem. Prezentovaná metoda neurčitostního modelování je velice univerzální a aplikovatelná na libovolný stavový model.