scholarly journals An Active System for Visually-Guided Reaching in 3D across Binocular Fixations

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Ester Martinez-Martin ◽  
Angel P. del Pobil ◽  
Manuela Chessa ◽  
Fabio Solari ◽  
Silvio P. Sabatini
Keyword(s):  
Visual Information ◽  
Vision System ◽  
Active Vision ◽  
Real Data ◽  
Disparity Estimation ◽  
Visually Guided ◽  
Active System ◽  
Visuomotor Coordination ◽  
Visually Guided Reaching ◽  
Motor Information

Based on the importance of relative disparity between objects for accurate hand-eye coordination, this paper presents a biological approach inspired by the cortical neural architecture. So, the motor information is coded in egocentric coordinates obtained from the allocentric representation of the space (in terms of disparity) generated from the egocentric representation of the visual information (image coordinates). In that way, the different aspects of the visuomotor coordination are integrated: an active vision system, composed of two vergent cameras; a module for the 2D binocular disparity estimation based on a local estimation of phase differences performed through a bank of Gabor filters; and a robotic actuator to perform the corresponding tasks (visually-guided reaching). The approach’s performance is evaluated through experiments on both simulated and real data.

scholarly journals A Mirror-Based Active Vision System for Underwater Robots: From the Design to Active Object Tracking Application

2021 ◽  
Vol 8 ◽  
Author(s):  
Noel Cortés-Pérez ◽  
Luz Abril Torres-Méndez
Keyword(s):  
Object Tracking ◽  
High Speed ◽  
Vision System ◽  
Lightweight Design ◽  
Research Work ◽  
Active Vision ◽  
Easy Access ◽  
Underwater Robot ◽  
Active System ◽  
Underwater Robots

A mirror-based active system capable of changing the view’s direction of a pre-existing fixed camera is presented. The aim of this research work is to extend the perceptual tracking capabilities of an underwater robot without altering its structure. The ability to control the view’s direction allows the robot to explore its entire surroundings without any actual displacement, which can be useful for more effective motion planning and for different navigation strategies, such as object tracking and/or obstacle evasion, which are of great importance for natural preservation in environments as complex and fragile as coral reefs. Active vision systems based on mirrors had been used mainly in terrestrial platforms to capture the motion of fast projectiles using high-speed cameras of considerable size and weight, but they had not been used on underwater platforms. In this sense, our approach incorporates a lightweight design adapted to an underwater robot using affordable and easy-access technology (i.e., 3D printing). Our active system consists of two arranged mirrors, one of which remains static in front of the robot’s camera, while the orientation of the second mirror is controlled by two servomotors. Object tracking is performed by using only the pixels contained on the homography of a defined area in the active mirror. HSV color space is used to reduce lighting change effects. Since color and geometry information of the tracking object are previously known, a window filter is applied over the H-channel for color blobs detection, then, noise is filtered and the object’s centroid is estimated. If the object is lost, a Kalman filter is applied to predict its position. Finally, with this information, an image PD controller computes the servomotor articular values. We have carried out experiments in real environments, testing our active vision system in an object-tracking application where an artificial object is manually displaced on the periphery of the robot and the mirror system is automatically reconfigured to keep such object focused by the camera, having satisfactory results in real time for detecting objects of low complexity and in poor lighting conditions.

scholarly journals Efference Copy Provides the Eye Position Information Required for Visually Guided Reaching

1998 ◽  
Vol 80 (3) ◽  
pp. 1605-1608 ◽  
Author(s):  
Richard F. Lewis ◽  
Bertrand M. Gaymard ◽  
Rafael J. Tamargo
Keyword(s):  
Visual Information ◽  
Constant Error ◽  
Efference Copy ◽  
Eye Position ◽  
Sufficient Information ◽  
Visually Guided ◽  
Position Information ◽  
Visually Guided Reaching ◽  
Position Signal ◽  
The Mean

Lewis, Richard F., Bertrand M. Gaymard, and Rafael J. Tamargo. Efference copy provides the eye position information required for visually guided reaching. J. Neurophysiol. 80: 1605–1608, 1998. The contribution of extraocular muscle (EOM) proprioception to the eye position signal used to transform retinotopic visual information to a craniotopic reference frame remains uncertain. In this study we examined the effects of unilateral and bilateral proprioceptive deafferentation of the EOMs on the accuracy of reaching movements directed to visual targets. No significant changes occurred in the mean accuracy (constant error) or variance (variable error) of pointing after unilateral or bilateral deafferentation. We concluded that in normal animals efference copy provides sufficient information about orbital eye position to code space in craniotopic coordinates.

scholarly journals The Conformal Camera in Modeling Binocular Vision

2016 ◽  
Author(s):  
Jacek Turski
Keyword(s):  
Visual Information ◽  
Vision System ◽  
Riemann Sphere ◽  
Geometric Analysis ◽  
Internal Representation ◽  
Active Vision ◽  
Crystalline Lens ◽  
Mathematical Framework ◽  
Camera Model ◽  
Primate Vision

Primate vision is an active process that constructs a stable internal representation of the 3D world based on 2D sensory inputs that are inherently unstable due to incessant eye movements. We present here a mathematical framework for processing visual information for a biologically-mediated active vision stereo system with asymmetric conformal cameras. This model utilizes the geometric analysis on the Riemann sphere developed in the group-theoretic framework of the conformal camera, thus far only applicable in modeling monocular vision. The asymmetric conformal camera model constructed here includes the fovea’s asymmetric displacement on the retina and the eye’s natural crystalline lens tilt and decentration, as observed in ophthalmological diagnostics. We extend the group-theoretic framework underlying the conformal camera to the stereo system with asymmetric conformal cameras. Our numerical simulation shows that the 1 theoretical horopter curves in this stereo system are conics that well approximate the empirical longitudinal horopters of the primate vision system.

scholarly journals Evolutionary active vision system: from 2D to 3D

2019 ◽  
pp. 105971231987447
Author(s):  
Olalekan Lanihun ◽  
Bernie Tiddeman ◽  
Patricia Shaw ◽  
Elio Tuci
Keyword(s):  
Visual Information ◽  
Vision System ◽  
Three Dimensional ◽  
Active Vision ◽  
Local Binary Patterns ◽  
Outdoor Environment ◽  
Movement Strategies ◽  
3D Environments ◽  
2D And 3D ◽  
Motor Strategies

Biological vision incorporates intelligent cooperation between the sensory and the motor systems, which is facilitated by the development of motor skills that help to shape visual information that is relevant to a specific vision task. In this article, we seek to explore an approach to active vision inspired by biological systems, which uses limited constraints for motor strategies through progressive adaptation via an evolutionary method. This type of approach gives freedom to artificial systems in the discovery of eye-movement strategies that may be useful to solve a given vision task but are not known to us. In the experiment sections of this article, we use this type of evolutionary active vision system for more complex natural images in both two-dimensional (2D) and three-dimensional (3D) environments. To further improve the results, we experiment with the use of pre-processing the visual input with both the uniform local binary patterns (ULBP) and the histogram of oriented gradients (HOG) for classification tasks in the 2D and 3D environments. The 3D experiments include application of the active vision system to object categorisation and indoor versus outdoor environment classification. Our experiments are conducted on the iCub humanoid robot simulator platform.

scholarly journals Efficacy of the use of unaffected hand containment in unimanual intensive therapy to increase visuomotor coordination in children with hemiplegia: a randomized controlled pilot study

2021 ◽  
Vol 12 ◽  
pp. 204062232110012
Author(s):  
Rocío Palomo-Carrión ◽  
Elisabeth Bravo-Esteban ◽  
Sara Ando-La Fuente ◽  
Purificación López-Muñoz ◽  
Inés Martínez-Galán ◽  
...  
Keyword(s):  
Reaction Time ◽  
Upper Limb ◽  
Visual Information ◽  
Intensive Therapy ◽  
Action Planning ◽  
Reaction Time Task ◽  
Group Differences ◽  
Visuomotor Coordination ◽  
Therapy Program ◽  
Anticipatory Action

Background: The capacity of children with hemiplegia to be engaged in anticipatory action planning is affected. There is no balance among spatial, proprioceptive and visual information, thus altering the affected upper limb visuomotor coordination. The objective of the present study was to assess the improvement in visuomotor coordination after the application of a unimanual intensive therapy program, with the use of unaffected hand containment compared with not using unaffected hand containment. Methods: A simple blind randomized clinical trial was realized. A total of 16 subjects with congenital infantile hemiplegia participated in the study with an age mean of 5.54 years old (SD:1.55). Two intensive protocols for 5 weeks of modified constraint-induced movement therapy (mCIMT) or unimanual therapy without containment (UTWC) were executed 5 days per week (2 h/day). Affected upper limb visuomotor coordination (reaction time, task total time, active range, dynamic grasp) was measured before–after intensive therapy using a specific circuit with different slopes (10°/15°). Results: Statistically significant inter-group differences were found after the intervention, with clinically relevant results for the mCIMT group not seen in UTWC, in the following variables: reaction time 10°slope ( p = 0.003, d = 2.44), reaction time 15°slope ( p = 0.002, d = 2.15) as well as for the task total time 10°slope ( p = 0.002, d = 2.25), active reach 10°slope ( p = 0.002, d = 2.7), active reach 15°slope ( p = 0.003, d = 2.29) and dynamic grasp 10°/15°slopes ( p = <0.001, d = 2.69). There were not statistically significant inter-group differences in the total task time with 15°slope ( p = 0.074, d = 1.27). Conclusions: The use of unaffected hand containment in mCIMT would allow improvements in the affected upper limb’s visuomotor coordination. Thus, it would favor clinical practice to make decisions on therapeutic approaches to increase the affected upper limb functionality and action planning in children diagnosed with infantile hemiplegia (4–8 years old).

Vibration Sensing of a Bridge Model Using a Multithread Active Vision System

2018 ◽  
Vol 23 (1) ◽  
pp. 179-189 ◽  
Author(s):  
Tadayoshi Aoyama ◽  
Makoto Chikaraishi ◽  
Akimasa Fujiwara ◽  
Liang Li ◽  
Mingjun Jiang ◽  
...  
Keyword(s):  
Vision System ◽  
Active Vision ◽  
Bridge Model ◽  
Vibration Sensing
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