The capacity of animals to navigate through familiar or novel environments depends crucially on the integration of a disparate set of self motion cues. The study begins with one of the most simple, planar visual motion, and investigates the cortical organisation of motion sensitive areas. It finds evidence of columnar organisation in hMT+ and a large scale map in V1. Chapter 3 extends this by using stimuli designed to emulate visual and auditory forward motion. It finds that participants are able to determine their direction with a precision close to that predicted by Bayesian integration. Predictions were made regarding neural processing through a modified divisive normalisation model, which was also used to fit the behavioural adaptation results. The integration of different modalities requires visual and auditory streams to combine at some stage within the sensory processing hierarchy. Previous research suggests the ventral intraparietal region (VIP) may be the seat of such integration. Chapter 4 tests whether VIP does combine these cues and whether the correlation between VIP and the unimodal regions changes depending on the coherence of unimodal stimuli. The presence of such modulation is predicted by some models, such as the divisive normalisation model. The processing of such egocentric self motion cues leads to the updating of allocentric representations, these are believed to be encoded by head direction cells and place cells. The experiment in chapter 5 uses a virtual reality stimulus during fMRI scanning to give participants the sense of moving and navigating. Their location in the virtual environment was decoded above chance from voxels in the hippocampus. No head direction signal was classified above chance from any of the three cortical regions investigated. We tentatively conclude that head direction is considerably more difficult to classify from the BOLD signal, possibly due to the homogeneous organisation of head direction cells.

The importance of physical motion in simulators for pilot training is strongly debated. The present experiment isolated different types of motion, a potentially important variable contributing to the controversy. Participants used a joystick to perform a target tracking task in a motion simulator built using a MOOG Stewart platform. Five training conditions compared training without motion (as one would train in a stationary simulator), with correlated motion, with disturbance motion, with disturbance motion isolated to the visual display, and with both correlated and disturbance motion. The test condition involved the full motion model with both correlated and disturbance motion. We analyzed speed and accuracy across training and test as well as strategic differences in joystick control. We found that training with disturbance provided better transfer to test conditions that included disturbance motion for accuracy, but not speed, and that training with disturbance motion produced different joystick control strategies compared to training without disturbance. / Thesis / Master of Science (MSc)

Full motion simulators are traditionally used in the flight industry to train pilots. They are used to add the sensation of acceleration in simulation to make it more "realistic". Clearly the motion envelop of the simulator is limited by physical constraints so the motion platform has to be stopped and returned to the center position after an acceleration cue, called washout. A key question is: which acceleration can a subject feel and which not, called the acceleration threshold. We are also interested in strength of accelerations for which a subject can detect the direction. Literature gives several results, but we found that some of these values seemed very low to us and the experiments were conducted on very specific groups of people like pilots, A.J.Benson and H.Vogel (1986), Schroeder (1999). Furthermore, we are simulating moving vehicles like a car or an air plane and are interested in the acceleration ranges in a noisy environment. Noisy, the noise is a result from the vibration of engines, rough roads and disturbances that are Gaussian. This thesis gives a literature review, implement the cueing procedure to make motion and vibration to do different experiment and analyze the results. / Thesis / Master of Computer Science (MCS)

Submitted by Andrea Hayashi (deachan@gmail.com) on 2016-06-28T13:32:24Z No. of bitstreams: 1 dissertacao-felipe-de-souza-antonio.pdf: 545326 bytes, checksum: 590267b412f92413fe1da672a36a85fa (MD5) / Approved for entry into archive by Andrea Hayashi (deachan@gmail.com) on 2016-06-28T13:33:15Z (GMT) No. of bitstreams: 1 dissertacao-felipe-de-souza-antonio.pdf: 545326 bytes, checksum: 590267b412f92413fe1da672a36a85fa (MD5) / Made available in DSpace on 2016-06-28T13:33:15Z (GMT). No. of bitstreams: 1 dissertacao-felipe-de-souza-antonio.pdf: 545326 bytes, checksum: 590267b412f92413fe1da672a36a85fa (MD5) Previous issue date: 2013-02-14 / Tendo como referência os escritos da Física de Aristóteles, o movimento, para os pensadores do século XIII, não somente diz respeito ao movimento local, mas também às mudanças quantitativa e qualitativa dos entes. A fim de justificar o movimento das coisas, isto é, a passagem da potência ao ato, grande parte dos escolásticos recorreu ao princípio aristotélico que diz: “tudo que se move é movido por outro”. Ademais, para alguns desses pensadores, até mesmo as alterações cognitivas e apetitivas que ocorrem nas potências da alma submetem-se a esse princípio. Às vésperas do século XIV, Duns Scotus rejeita a universalização do princípio aristotélico do movimento e sistematiza uma filosofia em favor do automovimento. Por conseguinte, o propósito desta dissertação é apresentar por que Scotus sustenta que não se pode afirmar a priori, isto é, por meio de princípios de validade universal e independentes da experiência, que toda e qualquer mudança é causada por outro. Tomando por referência as Questões sobre os livros da Metafísica de Aristóteles IX, q. 14, exponho o pensamento de Scotus, o qual diz que o automovimento não só é possível, mas também é a melhor explicação para muitos fatos empíricos: os acidentes simultâneos e não simultâneos; o movimento dos leves e graves; o movimento dos animais; bem como as alterações qualitativa, quantitativa, cognitiva e apetitiva que outrora eram exclusivamente explicadas pelo princípio aristotélico do movimento. Por fim, na conclusão, teço algumas considerações sobre a questão do automovimento e também apresento sucintamente o pensamento de Scotus sobre o automovimento da vontade. / For the 13th century thinkers the study of motion was plainly founded on the writings of Aristotle‟s physics which does not constrain the meaning of motion exclusively to local motion, but it also includes to its meaning the qualitative and quantitative changes of things. In order to explain the movement or changes of things, namely the passage from potency to act, the majority of the scholastic philosophers counted on the aristotelian cinesiological principle that says: “everything which is in motion is moved by another”. Moreover, for some scholastic philosophers even the changes regarding the powers of the soul, that is, alteration in the intellect and in the will, must undergo the cinesiological principle. On the eve of the fourteenth century, Duns Scotus rejects the aristotelian principle and systematizes a philosophy in favor of self-motion. Therefore, the purpose of this dissertation is to present why Scotus sustains we can not state a priori, i.e, through principles of universal scope and independent of experience, that self-motion is impossible; in other words, we can not say that any change is caused by another. Taking as reference the Questions on the metaphysics of Aristotle’s IX, q.14 by John Duns Scotus, I explain the thought of Scotus to whom selfmotion is not only possible, but it is also the best explanation to many empirical facts like: coeval and non coeval accidents; the motion of heavy and light things; animals‟ motion, as well as qualitative, quantitative, cognitive and appetitive changes that once were exclusively explained by the aristotelian principle of motion. Finally, in the conclusion, I make some comments about the self-motion issue and also introduce briefly Scotus‟ thought regarding self-motion in volition / TEDE

Made available in DSpace on 2015-07-22T20:49:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-01-01. Added 1 bitstream(s) on 2015-08-11T03:26:33Z : No. of bitstreams: 1 Publico-FelipedeSouzaAntonio.pdf: 522610 bytes, checksum: 2df298fce6c90f3e8bc78d335f550c16 (MD5) / Tendo como referência os escritos da Física de Aristóteles, o movimento, para os pensadores do século XIII, não somente diz respeito ao movimento local, mas também às mudanças quantitativa e qualitativa dos entes. A fim de justificar o movimento das coisas, isto é, a passagem da potência ao ato, grande parte dos escolásticos recorreu ao princípio aristotélico que diz: “tudo que se move é movido por outro”. Ademais, para alguns desses pensadores, até mesmo as alterações cognitivas e apetitivas que ocorrem nas potências da alma submetem-se a esse princípio. Às vésperas do século XIV, Duns Scotus rejeita a universalização do princípio aristotélico do movimento e sistematiza uma filosofia em favor do automovimento. Por conseguinte, o propósito desta dissertação é apresentar por que Scotus sustenta que não se pode afirmar a priori, isto é, por meio de princípios de validade universal e independentes da experiência, que toda e qualquer mudança é causada por outro. Tomando por referência as Questões sobre os livros da Metafísica de Aristóteles IX, q. 14, exponho o pensamento de Scotus, o qual diz que o automovimento não só é possível, mas também é a melhor explicação para muitos fatos empíricos: os acidentes simultâneos e não simultâneos; o movimento dos leves e graves; o movimento dos animais; bem como as alterações qualitativa, quantitativa, cognitiva e apetitiva que outrora eram exclusivamente explicadas pelo princípio aristotélico do movimento. Por fim, na conclusão, teço algumas considerações sobre a questão do automovimento e também apresento sucintamente o pensamento de Scotus sobre o automovimento da vontade. / For the 13th century thinkers the study of motion was plainly founded on the writings of Aristotle‟s physics which does not constrain the meaning of motion exclusively to local motion, but it also includes to its meaning the qualitative and quantitative changes of things. In order to explain the movement or changes of things, namely the passage from potency to act, the majority of the scholastic philosophers counted on the aristotelian cinesiological principle that says: “everything which is in motion is moved by another”. Moreover, for some scholastic philosophers even the changes regarding the powers of the soul, that is, alteration in the intellect and in the will, must undergo the cinesiological principle. On the eve of the fourteenth century, Duns Scotus rejects the aristotelian principle and systematizes a philosophy in favor of self-motion. Therefore, the purpose of this dissertation is to present why Scotus sustains we can not state a priori, i.e, through principles of universal scope and independent of experience, that self-motion is impossible; in other words, we can not say that any change is caused by another. Taking as reference the Questions on the metaphysics of Aristotle’s IX, q.14 by John Duns Scotus, I explain the thought of Scotus to whom self-motion is not only possible, but it is also the best explanation to many empirical facts like: coeval and non coeval accidents; the motion of heavy and light things; animals‟ motion, as well as qualitative, quantitative, cognitive and appetitive changes that once were exclusively explained by the aristotelian principle of motion. Finally, in the conclusion, I make some comments about the self-motion issue and also introduce briefly Scotus‟ thought regarding self-motion in volition / TEDE

Self-motion perception is based on the integration of visual (optic flow) and vestibular (inertial) sensory information. Previous research has shown that the relative contribution of visual and vestibular cues can change in real time based on the reliability of that information. The present study assessed whether initial velocity and acceleration magnitude influence the relative contribution of these cues to the detection of self-acceleration. Participants performed a simple response time task with visual and vestibular self-acceleration cues as targets. Visual optic flow was presented at three possible initial velocities of 3, 9, or 15 m/s, and accelerated to result in three possible final velocities of 21, 27, or 33 m/s. Corresponding vestibular cues were presented at magnitudes between 0.01 and 0.04 g. The self-acceleration cues were presented at three possible stimulus onset asynchronies (SOAs): visual-first (by 100 ms), in-sync, and vestibular-first (by 100 ms). We found that presenting the cues in-sync resulted in the fastest responses across all velocities and acceleration magnitudes. Interestingly, presenting the visual cue first resulted in a relative advantage over vestibular-first at the slowest initial velocity of 3 m/s, and vice versa for the fastest initial velocity of 15 m/s. The fastest overall responses for visual-first and in-sync were observed at 9 m/s. The present results support the hypothesis that velocity of optic flow can alter the relative contribution of visual and vestibular cues to the detection of self-acceleration. / Thesis / Master of Science (MSc) / This thesis contributes valuable insight into the emerging literature on how visual and vestibular cues are integrated to result in reliable self-motion perception. Specifically, this thesis provides evidence that velocity of optic flow plays an important role in mediating the relative weighting of visual and vestibular cues during acceleration perception.

The perception of self-motion draws on inputs from the visual, vestibular and proprioceptive systems. Decades of behavioural research has shed light on constructs such as multisensory weighting, heading perception, and sensory thresholds, that are involved in self-motion perception. Despite the abundance of knowledge generated by behavioural studies, there is a clear lack of research exploring the neural processes associated with full-body, multisensory self-motion perception in humans. Much of what is known about the neural correlates of self-motion perception comes from either the animal literature, or from human neuroimaging studies only administering visual self-motion stimuli. The goal of this thesis was to bridge the gap between understanding the behavioural correlates of full-body self-motion perception, and the underlying neural processes of the human brain. We used a high-fidelity motion simulator to manipulate the interaction of the visual and vestibular systems to gain insights into cognitive processes related to self-motion perception. The present line of research demonstrated that theta, alpha and beta oscillations are the underlying electrophysiological oscillations associated with self-motion perception. Specifically, the three empirical chapters combine to contribute two main findings to our understanding of self-motion perception. First, the beta band is an index of visual-vestibular weighting. We demonstrated that beta event-related synchronization power is associated with visual weighting bias, and beta event-related desynchronization power is associated with vestibular weighting bias. Second, the theta band is associated with direction processing, regardless of whether direction information is provided through the visual or vestibular system. This research is the first of its kind and has opened the door for future research to further develop our understanding of biomarkers related to self-motion perception. / Dissertation / Doctor of Philosophy (PhD) / As we move through the environment, either by walking, or operating a vehicle, our senses collect many different kinds of information that allow us to perceive factors such as, how fast we are moving, which direction we are headed in, or how other objects are moving around us. Many of our senses take in very different information, for example, the vestibular system processes information about our head movements, while our visual system processes information about incoming light waves. Despite how different all of this self-motion information can be, we still manage to have one smooth perception of our bodies moving through the environment. This smooth perception of self-motion is due to our senses sharing information with one another, which is called multisensory integration. Two of the most important senses for collecting information about self-motion are the visual and vestibular systems. To this point, very little is known about the biological processes in the brain while the visual and vestibular systems integrate information about self-motion. Understanding this process is limited because until recently, we have not had the technology or the methodology to adequately record the brain while physically moving people in a virtual environment. Our team developed a ground-breaking set of methodologies to solve this issue, and discovered key insights into brainwave patterns that take place in order for us to perceive ourselves in motion. There were two critical insights from our line of research. First, we identified a specific brainwave frequency (beta oscillations) that indexes integration between the visual and vestibular systems. Second, we demonstrated another brainwave frequency (theta oscillation) that is associated with perceiving which direction we are headed in, regardless of which sense this direction information is coming from. Our research lays the foundation for our understanding of biological processes of self-motion perception and can be applied to diagnosing vestibular disorders or improving pilot simulator training.

Redundant manipulators are widely used because they have a greater dexterity andversatility than nonredundant manipulators. In the redundant manipulators, thenumber of degrees of freedom are more than the required to manipulate objects atthe task space, which leads to a possibility to generate infinite number of solutions.For this reasons it has been a hot research topic to exploit the redundancy. Thisthesis work is focus on modeling and controlling redundant robot manipulator withseven degree of freedom (LWA 10 kg payload by Schunk). A literature review hasbeen prepared on the existing methods of exploiting the redundancy in the 7-DOFmanipulators at the velocity and position levels. The forward kinematic equationsare derived using the Denavit-Hartenberg method. The inverse kinematic problem issolved and the redundancy is exploited at the position level to avoid the computationalcomplexity and inaccuracy associated with exploiting the redundancy at the velocitylevel. The joint angles of the manipulator are computed in term of a redundancyparameter defining the self-motion in the manipulator. The relation between the jointangles and the redundancy parameter is exploited to avoid selecting the arm anglesthat violate the joint limits. The singularity configurations and robot workspace arealso studied in this thesis. An example is presented on how the self-motion of thearm appears when the end-effector is stationary. The methods are applied to followstraight line trajectories while preventing the joints to exceed the limits. The resultsfound showed how exploiting the redundancy at the position level is being exact withlow computational cost. The validity of the methods is verified by Robotics Toolboxsimulations.

No description available.

L'objectif principal de cette thèse est de mettre en évidence le rôle de la direction et du mouvement de la tête et des yeux dans la perception et le contrôle de trajectoires courbes, en référence aux propriétés des flux optiques générés par notre déplacement dans un environnement stable. Nous utilisons deux méthodes expérimentales : une approche comportementale sur simulateur de conduite et une approche psychophysique permettant d'évaluer les capacités d'observateurs humains à percevoir la direction du mouvement propre. Ces méthodes combinées visent à mettre en évidence les effets comportementaux d'une perception active de la direction du mouvement propre. L'introduction dresse l'état de la recherche sur les informations disponibles et les stratégies perceptives impliquées dans la prise de virage en conduite automobile. Ainsi, l'accent est à la fois mis sur le rôle du point de corde (dans le cas étudié d'un déplacement sur une route délimitée) et plus généralement sur le rôle du flux optique (description de la transformation apparente de l'environnement visuel lors du déplacement), soulignant notre capacité à interpréter spatialement le mouvement, mais aussi le caractère indissociable de la motricité et de la perception. Nous abordons ensuite le rôle des mouvements combinés des yeux et de la tête, dans une perspective fonctionnelle du contrôle du mouvement.Dans un premier chapitre expérimental, nous analysons les mouvements d'orientation de la tête lors de la prise de virage en conduite simulée. Nous montrons que les mouvements de la tête sont indépendants de la manipulation du volant et qu'ils participent activement à l'orientation du regard vers le point de corde. Dans un second chapitre expérimental, nous nous attachons à décrire les mouvements combinés des yeux et de la tête, en lien avec la géométrie de l'environnement routier. Dans une troisième partie, nous analysons plus finement le comportement du regard en lien avec la direction du point de corde et la vitesse locale du flux optique. Nous montrons à la fois que le point de corde correspond à un minimum local de vitesse optique et que la composante globale du flux optique induit un nystagmus optocinétique systématique. Enfin, lors d'une quatrième étude psychophysique, nous nous attachons à décrire finement l'effet de la variation de la direction du regard sur la discrimination de la direction du mouvement propre. Nous montrons que les seuils de discrimination de trajectoire sont minimaux lorsque le regard est orienté vers une zone de vitesse de flux minimal. Nous proposons finalement un modèle de détection de la trajectoire, basé sur une fraction de Weber des vitesses de flux fovéales, qui prédit très précisément les seuils expérimentaux. Les stratégies observées d'orientation du regard (combinaison des mouvements des yeux et de la tête) vers le point de corde sont compatibles avec une sélection optimale de l'information présente dans le flux optique. / The main purpose of this dissertation is to determine the role of the direction and movement of the eyes and the head in the perception and control of self-motion in curved trajectories, with respect to the properties of the optical flows generated in a stable environment. To do so, we used two experimental methods: a psychophysical approach which allows to assess human observers' ability to perceive the direction of self-motion; and a behavior-based approach on a driving simulator. The two methods combined should help to highlight active perception of self-motion.The introduction reviews the current knowledge of perceptuo-motor strategies during curve driving. In this context, we put a stress on both (1.) the particular role of the tangent point -- in the driving situation on a delimited road, and on the role of the optic flow in general (apparent transformation of the optic array during self-motion), emphasizing the capability of humans to spatially interpret the movement; and (2.) on the duality between movement and perception. We then address the role of head-and-eye combined movements, in a functional perspective of the control of self-motion. In a first experimental section, we analyze the oriented movements of the head in simulated curve driving. We demonstrate that head movements are independent from the handling of the steering wheel, and that they actively participate in the gaze orientation toward the tangent point.In a second experimental section, we set out to describe the combined movements of head and eyes, with respect to the geometry of the road environment. In a third section, we analyze in more details gaze behavior as a function of the tangent point direction and of the local speed of optical flow. We demonstrate that the tangent point corresponds to a local minimum of optic flow speed and that the global component of the optic flow induces a systematic optokinetic nystagmus. In a fourth section involving a psychophysical study, we scrutinize the effect of varying gaze direction on the discrimination of the direction of self-motion. We show that the trajectory discrimination thresholds are minimal when the gaze is oriented toward an area of minimum flow speed. We finally propose a model of trajectory change detection, relying on a Weber fraction of foveal flow speeds, predicting the experimental thresholds very precisely. The gaze orientation strategies we have observed (combination of head and eye movements) toward the tangent point are compatible with this model and with the hypothesis of an active an optimal selection of the information contained in the optical flow.