WMR navigation using local potential field corridors and narrow local occupancy grid perception

Path planning and control strategies applied to autonomous mobile robots should fulfil safety rules as well as achieve final goals. Trajectory planning applications should be fast and flexible to allow real time implementations as well as environment interactions. The methodology presented uses the on robot information as the meaningful data necessary to plan a narrow passage by using a corridor based on attraction potential fields that approaches the mobile robot to the final desired configuration. It employs local and dense occupancy grid perception to avoid collisions. The key goals of this research project are computational simplicity as well as the possibility of integrating this method with other methods reported by the research community. Another important aspect of this work consist in testing the proposed method by using a mobile robot with a perception system composed of a monocular camera and odometers placed on the two wheels of the differential driven motion system. Hence, visual data are used as a local horizon of perception in which trajectories without collisions are computed by satisfying final goal approaches and safety criteria

Local model predictive control experiences with differential driven wheeled mobile robots

This work extends a previously developed research concerning about the use of local model predictive control in differential driven mobile robots. Hence, experimental results are presented as a way to improve the methodology by considering aspects as trajectory accuracy and time performance. In this sense, the cost function and the prediction horizon are important aspects to be considered. The aim of the present work is to test the control method by measuring trajectory tracking accuracy and time performance. Moreover, strategies for the integration with perception system and path planning are briefly introduced. In this sense, monocular image data can be used to plan safety trajectories by using goal attraction potential fields

Agreement in interpersonal perception as a predictor of group performance

Resumen tomado de la publicaci??n

Foreign perception of sovereign risk : an event study of the colombian armed conflict

Este paper estudia la relación entre algunos de los eventos más importantes del conflicto colombiano con la percepción extranjera de riesgo soberano, medido por los Credit Default Swaps (CDS) de los bonos del Gobierno Colombiano. Usando dos metodologías relativamente recientes, yo estimo el efecto causal de los eventos de conflicto ampliamente cubierto por los medios internacionales. En primer lugar construyo un grupo de control sintético que funciona como contra factual de la serie real de los CDS colombianos pero en ausencia de eventos de conflicto. Segundo, estimo el efecto acumulado del evento bajo la metodología de retornos anormales acumulados. Los resultados sugieren que los efectos de los eventos de conflicto sobre la percepción extranjera de riesgo soberano dependen de las especificaciones de cada evento.

Relationship among children’s perception of parental relationship and parental empathy and prosocial behaviour during childhood

The objective of this work is to study if children’s perception of parental relationship and parental empathy can predict prosocial behaviour during childhood. The sample was composed of 934 Argentine children, aged 9 to 12, of middle socio-economical level. The participants completed Argentine scale of Children Perception of Parental relationship (richaud de Minzi, 2007), an Argentine adaptation of scale of Prosocial Behaviour (Caprara and Pastorelli, 1993) and a questionnaire to measure children’s perception of parental empathy (richaud de Minzi, 2006). structural equations modelling (sEM) analyses were conducted to explore our hypotheses. Six theoretical models fit the data very well. The results showed that parental styles of acceptance and pathological control impact on children prosocial behavior. Children’s perception of parental empathy was positively associated with children prosocial behavior. Finally, parental acceptance and pathological control were associated with children’s perception of parental empathy, but negligent parental behaviour did not.  

Drogue et délinquance chez les jeunes de Navarre : contribution sociologique a la perception.

Realidad del consumo de drogas y la delincuencia en los jóvenes. Relación entre uno y otro hecho. Funcionamiento hacia los mismos de las instancias de control. Imágenes que sobre los hechos tienen los adultos. Jóvenes: 2.246 jóvenes de 15-21 años de Navarra. Adultos: 300 educadores, policías municipales, padres de familia. Muestra de jóvenes: estratificación de sexo y edad, y azar. Adultos: no representativa. Elaboración de cuestionario para jóvenes, con preguntas sobre contacto y frecuencia de consumo de diferentes drogas, frecuencia en la comisión de diferentes tipos de delitos, veces en que ha sido objeto de las actuaciones de las diferentes instancias de control y variables sobre la familia, la educación, el trabajo, la religión, la sexualidad, la política y el ocio y tiempo libre. Cuestionario dirigido a los adultos en el cual debían de estimar en porcentajes las respuestas dadas por los jóvenes a su cuestionario. Informatización de los cuestionarios. Análisis de bivariables con test de x2 en la encuesta de jóvenes. Obtención de medias, desviaciones típicas y comparación con los resultados de la encuesta de jóvenes, en la encuesta realizada entre los adultos. Descripción de los datos obtenidos, creación de variables síntesis, cruce entre variables y medida de la asociación mediante test de x2 para encontrar la extensión de la droga y la delincuencia en los jóvenes, la relación y asociación entre uno y otro hecho, y la orientación de las instancias de control. Comparación de resultados de la encuesta de jóvenes con las imagenes de los adultos. El consumo de drogas es generalizado entre los jóvenes, siendo menos general el de drogas ilegales. El consumo de una droga ilegal no conduce inevitablemente al consumo habitual de dichas drogas ilegales. La comisión de delitos por parte de los jóvenes es un hecho prácticamente normal. Sin embargo, la delincuencia de los jóvenes es cuantitativamente diferente de la reflejada por las instancias de control y cualitativamente diferente de la gran delincuencia. Droga y delincuencia están asociadas significativamente, pero no se identifican en los jóvenes. El control se centra sobre los jóvenes y la droga. La realidad descubierta sitúa en un punto más preciso los problemas de la droga y la delincuencia en los jóvenes y evidencia las falsas representaciones existentes sobre su asociación. Detecta la focalización de las instancias de control sobre los jóvenes y la droga y desvela la empresa ideológica que ello comporta. Precisa la deformación por exageración o defecto de las representaciones de los adultos sobre los jóvenes.

Assessment of the effects of a cooperative play programme for children aged 10-11 years on social adaptation and on the perception that parents, teachers and peers have of children's prosocial behaviours. 'Evaluación de los efectos de un programa de juego cooperativo para los niños de 10-11 años en la adapatación social y en la percepción que padres, profesores y compañeros tienen de las conductas prosociales de los niños'.

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Local model predictive control for navigation of a wheeled mobile robot using monocular information

Aquesta tesi està inspirada en els agents naturals per tal de planificar de manera dinàmica la navegació d'un robot diferencial de dues rodes. Les dades dels sistemes de percepció són integrades dins una graella d'ocupació de l'entorn local del robot. La planificació de les trajectòries es fa considerant la configuració desitjada del robot, així com els vértexs més significatius dels obstacles més propers. En el seguiment de les trajectòries s'utilitzen tècniques locals de control predictiu basades en el model, amb horitzons de predicció inferiors a un segon. La metodologia emprada és validada mitjançant nombrosos experiments.

The role of visual and nonvisual information in the control of locomotion

During locomotion, retinal flow, gaze angle, and vestibular information can contribute to one's perception of self-motion. Their respective roles were investigated during active steering: Retinal flow and gaze angle were biased by altering the visual information during computer-simulated locomotion, and vestibular information was controlled through use of a motorized chair that rotated the participant around his or her vertical axis. Chair rotation was made appropriate for the steering response of the participant or made inappropriate by rotating a proportion of the veridical amount. Large steering errors resulted from selective manipulation of retinal flow and gaze angle, and the pattern of errors provided strong evidence for an additive model of combination. Vestibular information had little or no effect on steering performance, suggesting that vestibular signals are not integrated with visual information for the control of steering at these speeds.

Neural systems in the visual control of steering

Visual control of locomotion is essential for most mammals and requires coordination between perceptual processes and action systems. Previous research on the neural systems engaged by self-motion has focused on heading perception, which is only one perceptual subcomponent. For effective steering, it is necessary to perceive an appropriate future path and then bring about the required change to heading. Using function magnetic resonance imaging in humans, we reveal a role for the parietal eye fields (PEFs) in directing spatially selective processes relating to future path information. A parietal area close to PEFs appears to be specialized for processing the future path information itself. Furthermore, a separate parietal area responds to visual position error signals, which occur when steering adjustments are imprecise. A network of three areas, the cerebellum, the supplementary eye fields, and dorsal premotor cortex, was found to be involved in generating appropriate motor responses for steering adjustments. This may reflect the demands of integrating visual inputs with the output response for the control device.

Adaptive control of event integration

Identifying 2 target stimuli in a rapid stream of visual symbols is much easier if the 2nd target appears immediately after the 1st target (i.e., at Lag 1) than if distractor stimuli intervene. As this phenomenon comes with a strong tendency to confuse the order of the targets, it seems to be due to the integration of both targets into the same attentional episode or object file. The authors investigated the degree to which people can control the temporal extension of their (episodic) integration windows by manipulating the expectations participants had with regard to the time available for target processing. As predicted, expecting more time to process increased the number of order confusions at Lag 1. This was true for between-subjects and within-subjects (trial-to-trial) manipulations, suggesting that integration windows can be adapted actively and rather quickly.

Action preparation helps and hinders perception of action.

Several theories of the mechanisms linking perception and action require that the links are bidirectional, but there is a lack of consensus on the effects that action has on perception. We investigated this by measuring visual event-related brain potentials to observed hand actions while participants prepared responses that were spatially compatible (e.g., both were on the left side of the body) or incompatible and action type compatible (e.g., both were finger taps) or incompatible, with observed actions. An early enhanced processing of spatially compatible stimuli was observed, which is likely due to spatial attention. This was followed by an attenuation of processing for both spatially and action type compatible stimuli, likely to be driven by efference copy signals that attenuate processing of predicted sensory consequences of actions. Attenuation was not response-modality specific; it was found for manual stimuli when participants prepared manual and vocal responses, in line with the hypothesis that action control is hierarchically organized. These results indicate that spatial attention and forward model prediction mechanisms have opposite, but temporally distinct, effects on perception. This hypothesis can explain the inconsistency of recent findings on action-perception links and thereby supports the view that sensorimotor links are bidirectional. Such effects of action on perception are likely to be crucial, not only for the control of our own actions but also in sociocultural interaction, allowing us to predict the reactions of others to our own actions.

Motion detection and motion verbs: language affects low-level visual perception

Recent theories propose that semantic representation and sensorimotor processing have a common substrate via simulation. We tested the prediction that comprehension interacts with perception, using a standard psychophysics methodology.While passively listening to verbs that referred to upward or downward motion, and to control verbs that did not refer to motion, 20 subjects performed a motion-detection task, indicating whether or not they saw motion in visual stimuli containing threshold levels of coherent vertical motion. A signal detection analysis revealed that when verbs were directionally incongruent with the motion signal, perceptual sensitivity was impaired. Word comprehension also affected decision criteria and reaction times, but in different ways. The results are discussed with reference to existing explanations of embodied processing and the potential of psychophysical methods for assessing interactions between language and perception.

Perception and haptics

For people with motion impairments, access to and independent control of a computer can be essential. Symptoms such as tremor and spasm, however, can make the typical keyboard and mouse arrangement for computer interaction difficult or even impossible to use. This paper describes three approaches to improving computer input effectivness for people with motion impairments. The three approaches are: (1) to increase the number of interaction channels, (2) to enhance commonly existing interaction channels, and (3) to make more effective use of all the available information in an existing input channel. Experiments in multimodal input, haptic feedback, user modelling, and cursor control are discussed in the context of the three approaches. A haptically enhanced keyboard emulator with perceptive capability is proposed, combining approaches in a way that improves computer access for motion impaired users.

Dynamic vergence telepresence system incorporating active gaze control

Visual Telepresence system which utilize virtual reality style helmet mounted displays have a number of limitations. The geometry of the camera positions and of the display is fixed and is most suitable only for viewing elements of a scene at a particular distance. In such a system, the operator's ability to gaze around without use of head movement is severely limited. A trade off must be made between a poor viewing resolution or a narrow width of viewing field. To address these limitations a prototype system where the geometry of the displays and cameras is dynamically controlled by the eye movement of the operator has been developed. This paper explores the reasons why is necessary to actively adjust both the display system and the cameras and furthermore justifies the use of mechanical adjustment of the displays as an alternative to adjustment by electronic or image processing methods. The electronic and mechanical design is described including optical arrangements and control algorithms, An assessment of the performance of the system against a fixed camera/display system when operators are assigned basic tasks involving depth and distance/size perception. The sensitivity to variations in transient performance of the display and camera vergence is also assessed.