A large negative spike potential, which is closely related to the onset of saccadic eyemovements, can be recorded from electrodes adjacent to the orbits. This potential, thepresaccadic spike potential, has often been regarded as an artefact related to eyemovement recordings and little work has been performed to establish its normal waveformand parameters. A positive spike potential, exactly coincident with the frontal negativespike, has also been recorded from electrodes positioned over the posterior scalp andthere has been some debate regarding any possible relationship between the twopotentials. The frontal spike potential has been associated with motor unit activity in theextraocular muscles prior to the saccade. This thesis investigates both the large anteriorand smaller posterior spike potentials and relates these recordings to the saccadic eyemovements associated with them. The anterior spike potential has been recorded from normal subjects to ascertain its normallatency and amplitude parameters for both horizontal and vertical saccades. A relationshipbetween saccade size and spike potential amplitude is described, the spike potentialamplitude reducing with smaller saccades. The potential amplitude also reduces withadvancing age. Studying the topographical distribution of the spike potential across thescalp shows the posterior spike activity may arise from potential spread of the larger frontalspike potential. Spike potential recordings from subjects with anomalous eye movements further implicate the extraocular muscles and their innervation in the generation of the spike potential. These recordings indicate that the spike potential may have some use as a clinical recording from patients with disease conditions affecting either their extraocular muscles or the innervational pathways to these muscles. Further recordings of the potential are necessary, however, to determine the exact nature of the changes which may occur with such conditions.

¡@¡@It has been for a long time to develop systems of eye control, which are related to a variety of techniques, such as signal/image processing, characteristics of face identifying/tracking, action-mappings, etc. In terms of implementations, the acquisition of data can be done by either special instruments or by general devices. Such systems can be applied to many fields, for instance, military, medicine, entertainments, and other tasks that are fitted. And for the similar system, the performance differs due to the disparity of distinct situations and the way to use it. ¡@¡@In this thesis, we present a system that takes a sequence of images of a user as inputs, and then integrates methods of elliptical model of head, dual states of eyes, deformable templates, and the most yield filter to track the user¡¦s eyes. A coarse-to-fine strategy is used to rapidly locate the region of eyes and to get the information of eyes in order to translate into corresponding operations on machines. The experiment shows that our system is quite robust and fast so that it can help people who are unable to use physical body well.

Made available in DSpace on 2014-12-17T14:56:01Z (GMT). No. of bitstreams: 1 AllanAAFS.pdf: 1304979 bytes, checksum: 691afb58d42d67dd5158ddcf00b02ce5 (MD5) Previous issue date: 2005-03-22 / This work proposes a kinematic control scheme, using visual feedback for a robot arm with five degrees of freedom. Using computational vision techniques, a method was developed to determine the cartesian 3d position and orientation of the robot arm (pose) using a robot image obtained through a camera. A colored triangular label is disposed on the robot manipulator tool and efficient heuristic rules are used to obtain the vertexes of that label in the image. The tool pose is obtained from those vertexes through numerical methods. A color calibration scheme based in the K-means algorithm was implemented to guarantee the robustness of the vision system in the presence of light variations. The extrinsic camera parameters are computed from the image of four coplanar points whose cartesian 3d coordinates, related to a fixed frame, are known. Two distinct poses of the tool, initial and final, obtained from image, are interpolated to generate a desired trajectory in cartesian space. The error signal in the proposed control scheme consists in the difference between the desired tool pose and the actual tool pose. Gains are applied at the error signal and the signal resulting is mapped in joint incrementals using the pseudoinverse of the manipulator jacobian matrix. These incrementals are applied to the manipulator joints moving the tool to the desired pose / Este trabalho prop?e um esquema de controle cinem?tico, utilizando realimenta??o visual para um bra?o rob?tico com cinco graus de liberdade. Foi desenvolvido um m?todo que utiliza t?cnicas de vis?o computacional, para a determina??o da posi??o e orienta??o cartesiana tridimensional (pose) do bra?o rob?tico a partir da imagem do mesmo fornecida por uma c?mera. Um r?tulo triangular colorido ? disposto sobre a garra do manipulador rob?tico e regras heur?sticas eficientes s?o utilizadas para obter os v?rtices desse r?tulo na imagem. M?todos num?ricos s?o usados para recupera??o da pose da garra a partir desses v?rtices. Um esquema de calibra??o de cores fundamentado no algoritmo K-means foi implementado de modo a garantir a robustez do sistema de vis?o na presen?a de varia??es na ilumina??o. Os par?metros extr?nsecos da c?mera s?o calibrados usando-se quatro pontos coplanares extra?dos da imagem, cujas posi??es no plano cartesiano em rela??o a um referencial fixo s?o conhecidas. Para duas poses distintas da garra, inicial e final, adquiridas atrav?s da imagem, interpola-se uma trajet?ria de refer?ncia em espa?o cartesiano. O esquema de controle proposto possui como sinal de erro a diferen?a entre a pose de refer?ncia e a pose atual da garra. Ap?s a aplica??o de ganhos, o sinal de erro ? mapeado em incrementos de junta utilizando-se a pseudoinversa do jacobiano do manipulador. Esses incrementos s?o aplicados ?s juntas do manipulador, deslocando a garra para a pose de refer?ncia