Coordination œil-main | EPFL Graph Search

thumb|Test de coordination œil-main en 1943 La coordination œil-main (ou main-œil) est le contrôle coordonné entre les mouvements des yeux et des mains. L’information visuelle et les signaux proprioceptifs sont analysés ensemble dans le but de contrôler l’extension des bras et la manipulation des objets ainsi que le contrôle du mouvement des yeux. Presque chaque mouvement du corps humain est coordonné avec l’assistance de la perception visuelle. De cette manière, le cerveau peut générer un modèle de l’environnement qui permet l’interaction précise avec la réalité physique. Plusieurs activités ont été et sont étudiées au sujet de la coordination œil-main, par exemple pratiquer un sport comme le tennis de table, jouer d’un instrument de musique en lisant une partition, jouer aux jeux vidéo, copier manuellement des documents, et même préparer du thé. La coordination œil-main fait partie des mécanismes et des gestes quotidiens. Sans une coordination efficace, beaucoup de gens ne pourraie

Visuomotor Coordination in Reach-To-Grasp Tasks: From Humans to Humanoids and Vice Versa

Luka Lukic

Understanding the principles involved in visually-based coordinated motor control is one of the most fundamental and most intriguing research problems across a number of areas, including psychology, neuroscience, computer vision and robotics. Not very much is known regarding computational functions that the central nervous system performs in order to provide a set of requirements for visually-driven reaching and grasping. Additionally, in spite of several decades of advances in the field, the abilities of humanoids to perform similar tasks are by far modest when needed to operate in unstructured and dynamically changing environments. More specifically, our first focus is understanding the principles involved in human visuomotor coordination. Not many behavioral studies considered visuomotor coordination in natural, unrestricted, head-free movements in complex scenarios such as obstacle avoidance. To fill this gap, we provide an assessment of visuomotor coordination when humans perform prehensile tasks with obstacle avoidance, an issue that has received far less attention. Namely, we quantify the relationships between the gaze and arm-hand systems, so as to inform robotic models, and we investigate how the presence of an obstacle modulates this pattern of correlations. Second, to complement these observations, we provide a robotic model of visuomotor coordination, with and without the presence of obstacles in the workspace. The parameters of the controller are solely estimated by using the human motion capture data from our human study. This controller has a number of interesting properties. It provides an efficient way to control the gaze, arm and hand movements in a stable and coordinated manner. When facing perturbations while reaching and grasping, our controller adapts its behavior almost instantly, while preserving coordination between the gaze, arm, and hand. In the third part of the thesis, we study the neuroscientific literature of the primates. We here stress the view that the cerebellum uses the cortical reference frame representation. The cerebellum by taking into account this representation performs closed-loop programming of multi-joint movements and movement synchronization between the eye-head system, arm and hand. Based on this investigation, we propose a functional architecture of the cerebellar-cortical involvement. We derive a number of improvements of our visuomotor controller for obstacle-free reaching and grasping. Because this model is devised by carefully taking into account the neuroscientific evidence, we are able to provide a number of testable predictions about the functions of the central nervous system in visuomotor coordination. Finally, we tackle the flow of the visuomotor coordination in the direction from the arm-hand system to the visual system. We develop two models of motor-primed attention for humanoid robots. Motor-priming of attention is a mechanism that implements prioritizing of visual processing with respect to motor-relevant parts of the visual field. Recent studies in humans and monkeys have shown that visual attention supporting natural behavior is not exclusively defined in terms of visual saliency in color or texture cues, rather the reachable space and motor plans present the predominant source of this attentional modulation. Here, we show that motor-priming of visual attention can be used to efficiently distribute robot's computational resources devoted to visual processing.

EPFL2015

Coordination-Driven Monolayer-to-Bilayer Transition in Two-Dimensional Metal–Organic Networks

Mina Moradi, Patrick Shahgaldian, Henning Paul-Julius Stahlberg

We report on monolayer-to-bilayer transitions in 2D metal–organic networks (MONs) from amphiphiles supported at the water–air interface. Functionalized calix[4]arenes are assembled through the coordination of selected transition metal ions to yield monomolecular 2D crystalline layers. In the presence of Ni(II) ions, interfacial self-assembly and coordination yields stable monolayers. Cu(II) promotes 2D coordination of a monolayer which is then diffusively reorganizing, nucleates, and grows a progressive amount of second layer islands. Atomic force microscopic data of these layers after transfer onto solid substrates reveal crystalline packing geometries with submolecular resolution as they are varying in function of the building blocks and the kinetics of the assembly. We assign this monolayer-to-bilayer transition to a diffusive reorganization of the initial monolayers owing to chemical vacancies of the predominant coordination motif formed by Cu2+ ions. Our results introduce a new dimension into the controlled monolayer-to-multilayer architecturing of 2D metal–organic networks.

2021

Learning robotic eye–arm–hand coordination from human demonstration: a coupled dynamical systems approach

Aude Billard, Luka Lukic, José Santos-Victor

We investigate the role of obstacle avoidance in visually guided reaching and grasping movements. We report on a human study in which subjects performed prehensile motion with obstacle avoidance where the position of the obstacle was systematically varied across trials. These experiments suggest that reaching with obstacle avoidance is organized in a sequential manner, where the obstacle acts as an intermediary target. Furthermore, we demonstrate that the notion of workspace traveled by the hand is embedded explicitly in a forward planning scheme, which is actively involved in detecting obstacles on the way when performing reaching. We find that the gaze proactively coordinates the pattern of eye-arm motion during obstacle avoidance. This study provides also a quantitative assessment of the coupling between the eye-arm-hand motion. We show that the coupling follows regular phase dependencies, and is unaltered during obstacle avoidance. These observations provide a basis for the design of a computational model. Our controller extends the coupled dynamical systems (CDS) framework and provides fast and synchronous control of the eyes, the arm and the hand within a single and compact framework, mimicking similar control system found in humans. We validate our model for visuomotor control of a humanoid robot.

Springer2014

Visuomotor Coordination in Reach-To-Grasp Tasks: From Humans to Humanoids and Vice Versa

Luka Lukic

EPFL2015