Curvic couplings have been widely applied in industry and almost can be seen in the index table. Following the development of the precision machine industry, except the manufacturing precision, the positioning accuracy is also concerned to meet the demands for curvic couplings. The aim of this thesis is to investigate on manufacturing errors and positioning accuracy of curvic couplings. Discuss the geometric and indexing characteristics of curvic couplings firstly. In the meantime, the new parameter tooth surface of curvic couplings is derived by tooth generating theory. Than, mathematical models are established to simulate curvic couplings at present that are manufactured by grinding machine with different setting errors. Secondly, the practical examples based on the effects of elemental error on the manufacturing error are investigated. Finally, an experimental apparatus is built to measure the actual positioning accuracy of curvic couplings at different input speeds.

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GENERAL CHARACTERISTIC OF THE DISSERTATION Topicality of the problem Prosthesis in orthopaedic technique are constructions that act as leg function reproduction and for external normal view of the leg. It is a technique giving a possibility to adapt to the society and live a full-fledged life, when one or another limb is lost. By the data, declared by the world health society, people with a disability include 10 % of all world population, among them people over 80 years old. More and more orthopaedic techniques are produced in Lithuania at present. The production, manufactured in our country keeps in step with world design and quality in foreign countries and they are 5–6 times cheaper. The main aim of the designers and constructors of orthopaedic techniques is to design and produce functional and high quality lower limbs prosthesis and apparatus. In the meantime, the same as abroad, in Lithuania the production processes of the prosthesis are automated but not so much to ensure a good quality of the prosthesis. Sometimes it is very hard to make prosthesis of adequate size to a patient that prosthesis implicitly fits just to the patient. Also, it is very hard to adjust it, ensuring the same length as the residual limb which should precisely correspond to the lost limb of the changeable loads chains of the prosthesis periodically are deformed during walking. In other words, the length of the prosthesis changes during gait. Thus, it is very important to set the limits of... [to full text]

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L'objectif de ce travail est de concevoir une nouvelle interface haptique en vue de son exploitation pour la chirurgie mini-invasive. La technique d'anastomose ciblée consiste à réunir deux parties désolidarisées d'une artère par des sutures et des nœuds. Ceci est effectué par des outils chirurgicaux introduits à travers de petites incisions. Une étude expérimentale de cette tâche a été effectuée en collaboration avec des chirurgiens afin de caractériser leurs gestes. L'enregistrement de l'opération par un système de capture de mouvement a permis d'identifier la nature et les gestes canoniques de cette technique. Une structure parallèle sphérique a été ensuite adoptée comme base de l'interface haptique. Cette architecture présente un centre fixe de rotation semblable au point d'incision réel et offre les trois degrés de liberté de rotation nécessaires autours de ce point. Une étude détaillée de cette architecture suivie d'une phase d'optimisation, a permis d'adapter la structure à l'application chirurgicale. L'optimisation, basée sur un algorithme générique, a porté dans un premier lieu sur l'espace de travail de la tâche. La dextérité de la structure a été ensuite prise en compte. Une phase de conception basée sur les paramètres résultants de cette optimisation a aboutie à la réalisation d'un premier prototype. L'influence des erreurs de fabrication sur l'orientation de la plateforme a été aussi traitée dans ce travail afin de déterminer les plages des défauts admissibles. Une modélisation, utilisant les torseurs de petits déplacements, a été élaborée.La dernière partie de ce travail porte sur la commande a retour d'effort de l'interface. Un banc d'essais à 1 degré de liberté a été réalisé afin de tester les différents schémas de contrôle pour la téléopération. Les essais en simulation on permit de dresser une vue comparative de ces schémas. / The aim of this work is to develop a new haptic interface to perform a minimally invasive surgery. The targeted anastomosis technique consists of the surgical binding of a ruptured blood vessel, using sutures and knots. This task is performed by surgical tools inserted through small incisions. An experimental study of this task was conducted in collaboration with surgeons in order to characterize their gesture. The recording of the operation by a motion capture system helped identifying the nature and the canonical actions of this technique. A spherical parallel mechanism (SPM) was then adopted as a basis for the haptic interface. This architecture has a fixed center of rotation similar to the real incision point and offers the three required degrees of freedom of rotation around that point. A detailed study of the architecture followed by an optimization procedure led to a suitable mechanism for the surgical application. The optimization, which is based on a generic algorithm, used the workspace of the task as a criterion. Then the dexterity of the structure was taken into account. A design phase based on the parameters resulting from this optimization led to building the first prototype.The influence of manufacturing errors on the orientation of the platform was also addressed in this work to determine the ranges of allowable defects. The manufacturing errors are modeled by screws of small displacement in order to determine their effect on the orientation error of the end effector. The last part of this work focuses on the command of the force feedback interface. An experimental setup made out of a one degree of freedom system, was built to test different control schemes for teleoperation. Simulation trials allowed developing a comparative view of these schemes.