Submitted by Mario BC (mario@bc.ufrpe.br) on 2016-08-12T12:56:30Z No. of bitstreams: 1 Barbara Lins Caldas de Moraes.pdf: 1002020 bytes, checksum: 55835be7452bb5679593acd3c7c7c122 (MD5) / Made available in DSpace on 2016-08-12T12:56:30Z (GMT). No. of bitstreams: 1 Barbara Lins Caldas de Moraes.pdf: 1002020 bytes, checksum: 55835be7452bb5679593acd3c7c7c122 (MD5) Previous issue date: 2013-02-26 / Wild capuchin monkeys use stones tools to access food items that otherwise would be unavailable, as encapsulated fruits and seeds. The successful completion of this activity not only requires the selection of the suitable tool, but also the correct technique. In order to analyze if the stone tools used by the capuchin monkeys are adjusted to the type of food item consumed and if this adjustment entails variations or behavioral adaptations to accomplish the task, stone tools and techniques used by animals to process five distinct food items, were compared. The study was conducted in an area of Pernambuco’s semiarid Caatinga, located in Serra Talhada. Along 15 months, 257 sites were identified, characterized and monitored. Behaviors of using stones as tools were documented by camera traps. Accounted a ‘total of 395 stones, used as hammers to break of five food items: Syagrus oleracea, Manihot epruinosa, Pilosocereus pachycladus, Tacinga inamoena and Commiphora leptophloeos, these last three were not yet described as accessed auxiliary items by other populations of capuchin monkeys. The use of stones as tools to process the cactaceae revealed especially interested, such strategy is related to the presence of these item’s thorns. It was found also that the characteristics of food items such as hardness, size and the presence of spines influences the stone’s selection to be used as hammers. The postures adopted by the animals for activity breaks are similar to those already described in other studies, however behavioral adaptations in handling the tool are performed to increase its functionality. / Macacos-prego selvagens utilizam ferramentas de pedra para acessar itens alimentares que de outra forma estariam indisponíveis, como frutos encapsulados e sementes. O sucesso na realização desta atividade requer não só a seleção da ferramenta adequada, mas também a correta aplicação da técnica. A fim de analisar se as ferramentas de pedras utilizadas por macacos-prego são ajustadas de acordo com o tipo de item alimentar consumido e se esse ajuste acarreta variações ou adequações comportamentais para a realização da tarefa, ferramentas de pedras e técnicas aplicadas pelos animais, para o processamento de cinco itens alimentares distintos, foram comparadas. O estudo foi realizado em uma área de Caatinga no semiárido Pernambucano, localizada no município de Serra Talhada. Ao longo de 15 meses, 257 sítios de quebra foram identificados, caracterizados e monitorados. Comportamentos de uso de pedras como ferramentas foram documentados através de armadilhas fotográficas. Contabilizamos um total de 395 pedras utilizadas como martelos para a quebra de cinco itens alimentares: Syagrus oleracea, Manihot epruinosa, Pilosocereus pachycladus, Tacinga inamoena e Commiphora leptophloeos, estes três últimos ainda não descritos como itens acessados com o auxílio de ferramentas por outras populações de macacos-prego. O uso de pedras como ferramentas para o processamento das cactáceas revelou-se especialmente interessante, pois tal estratégia está relacionada à presença de espinhos destes itens. Fatores como a distribuição e o tamanho do item alimentar parecem influenciar nas escolhas feitas pelos animais no uso das bigornas. Constatou-se, também, que características dos itens alimentares como rigidez, tamanho e presença de espinhos influenciam na seleção das pedras utilizadas como martelos. As posturas adotadas pelos animais para a atividade de quebra são semelhantes às já descritas em outros estudos, mas adequações comportamentais na manipulação da ferramenta são realizadas para aumentar a sua funcionalidade.

The focus of the present work is natural human like grasping, for realistic performance simulations in digital human modelling (DHM) environment. The performance simulation for grasping in DHM is typically done through high level commands to the digital human models (DHMs). This calls for a natural and unambiguous scheme to describe a grasp which would implicitly accommodate variations due to the hand form, object form and hand kinematics. A novel relational description scheme is developed towards this purpose. The grasp is modelled as a spatio-temporal relationship between the patches (a closed region on the surface) in the hand and the object. The task dependency of the grasp affects only the choice of the relevant patches. Thus, the present scheme of grasp description enables a human like grasp description possible. Grasping can be simulated either in an interactive command mode as discussed above or in an autonomous mode. In the autonomous mode the patches have to be computed. It is done using a psychological concept, of affordance. This scheme is employed to select a tool from a set of tools. Various types of grasps a user may adopt while grasping a spanner for manipulating a nut is simulated. Grasping of objects by human evolves through distinct naturally occurring phases, such as re-oreintation, transport and preshape. Hand is taken to the object ballpark using a novel concept of virtual object. Before contact establishment hand achieves the shape similar to the global shape of the object, called preshaping. Various hand preshape strategies are simulating using an optimization scheme. Since the focus of the present work is human like grasping, the mechanism which drives the DHMs should also be anatomically pertinent. A methodology is developed wherein the hand-object contact establishment is done based on the anatomical observation of logarithmic spiral pattern during finger flexion. The effect of slip in presence of friction has been studied for 2D and 3D object grasping endeavours and a computational generation of the slip locus is done. The in-grasp slip studies are also done which simulates the finger and object response to slip. It is desirable that the grasping performance simulations be validated for diverse hands that people have. In the absence of an available database of articulated bio-fidelic digital hands, this work develops a semi-automatic methodology for developing subject specific hand models from a single pose 3D laser scan of the subject's hand. The methodology is based on the clinical evidence that creases and joint locations on human hand are strongly correlated. The hand scan is segmented into palm, wrist and phalanges, both manually and computationally. The computational segmentation is based on the crease markings in the hand scan, which is identified by explicitly painting them using a mesh processing software by the user. Joint locations are computed on this segmented hand. A 24 dof kinematic structure is automatically embedded into the hand scan. The joint axes are computed using a novel palm plane normal concept. The computed joint axes are rectified using the convergence, and intra-finger constraints. The methodology is significantly tolerant to the noise in the scan and the pose of the hand. With the proposed methodology articulated, realistic, custom hand models can be generated. Thus, the reported work presents a geometric framework for comprehensive simulation of grasping performance in a DHM environment.