scholarly journals Self-organising coordinate transformation with peaked and monotonic gain modulation in the primate dorsal visual pathway

2018 ◽  
Author(s):  
Daniel M. Navarro ◽  
Bedeho M. W. Mender ◽  
Hannah E. Smithson ◽  
Simon M. Stringer
Keyword(s):  
Coordinate Transformation ◽  
Reference Frames ◽  
Learning Rule ◽  
Visual Pathway ◽  
Visual Input ◽  
Eye Position ◽  
Gain Modulation ◽  
Important Challenge ◽  
First Time ◽  
Trace Learning

AbstractWe study a self-organising neural network model of how visual representations in the primate dorsal visual pathway are transformed from an eye-centred to head-centred frame of reference. The model has previously been shown to robustly develop head-centred output neurons with a standard trace learning rule [1], but only under limited conditions. Specifically it fails when incorporating visual input neurons with monotonic gain modulation by eye-position. Since eye-centred neurons with monotonic gain modulation are so common in the dorsal visual pathway, it is an important challenge to show how efferent synaptic connections from these neurons may self-organise to produce head-centred responses in a subpopulation of postsynaptic neurons. We show for the first time how a variety of modified, yet still biologically plausible, versions of the standard trace learning rule enable the model to perform a coordinate transformation from eye-centred to head-centred reference frames when the visual input neurons have monotonic gain modulation by eye-position.

scholarly journals Self-organising coordinate transformation with peaked and monotonic gain modulation in the primate dorsal visual pathway

PLoS ONE ◽  
2018 ◽  
Vol 13 (11) ◽  
pp. e0207961 ◽  
Author(s):  
Daniel M. Navarro ◽  
Bedeho M. W. Mender ◽  
Hannah E. Smithson ◽  
Simon M. Stringer
Keyword(s):  
Coordinate Transformation ◽  
Visual Pathway ◽  
Gain Modulation

Line-of-sight rate modeling and error analysis of inertial stabilized platforms by coordinate transformation

2017 ◽  
Vol 233 (4) ◽  
pp. 1317-1322 ◽  
Author(s):  
Qingjia Gao ◽  
Qiang Sun ◽  
Feng Qu ◽  
Jiang Wang ◽  
Xizhen Han ◽  
...  
Keyword(s):  
Theoretical Model ◽  
Target Tracking ◽  
Coordinate Transformation ◽  
Servo Control ◽  
Line Of Sight ◽  
Measurement Equations ◽  
Stabilized Platform ◽  
First Time ◽  
Guidance Laws ◽  
Key Parameter

Line-of-sight rate is the key parameter that enables inertial stabilized platforms to implement guidance laws successfully for target tracking or attacking. It is always obtained by experiments. In this article, a theoretical model of the line-of-sight rate is established for the first time, starting with the gimbal motion. The strategy to acquire line-of-sight rate is based on the servo control circuit. The measurement equations for line-of-sight rate are derived using a coordinate transformation. An error model is then obtained with the help of differentiation. The error of an inertial stabilized platform prototype is measured, showing that the line-of-sight rate error can be predicted accurately. Finally, a high-precision inertial stabilized platform is successfully designed and analyzed, with the accuracy of 0.06°/s and 0.37°/s when line-of-sight rates are set to 1.5°/s and 9°/s, respectively.

scholarly journals Suggested Integral Analysis for Chaos-Based Image Cryptosystems

Entropy ◽  
2019 ◽  
Vol 21 (8) ◽  
pp. 815 ◽  
Author(s):  
Miguel Angel Murillo-Escobar ◽  
Manuel Omar Meranza-Castillón ◽  
Rosa Martha López-Gutiérrez ◽  
César Cruz-Hernández
Keyword(s):  
Security Analysis ◽  
Analysis Framework ◽  
Integral Analysis ◽  
Aes Algorithm ◽  
Digital Chaos ◽  
Important Challenge ◽  
Encryption Algorithms ◽  
And Performance ◽  
First Time ◽  
New Algorithms

Currently, chaos-based cryptosystems are being proposed in the literature to provide confidentiality for digital images, since the diffusion effect in the Advance Encryption Standard (AES) algorithm is weak. Security is the most important challenge to assess in cryptosystems according to the National Institute of Standard and Technology (NIST), then cost and performance, and finally algorithm and implementation. Recent chaos-based image encryption algorithms present basic security analysis, which could make them insecure for some applications. In this paper, we suggest an integral analysis framework related to comprehensive security analysis, cost and performance, and the algorithm and implementation for chaos-based image cryptosystems. The proposed guideline based on 20 analysis points can assist new cryptographic designers to present an integral analysis of new algorithms. Future comparisons of new schemes can be more consistent in terms of security and efficiency. In addition, we present aspects regarding digital chaos implementation, chaos validation, and key definition to improve the security of the overall cryptosystem. The suggested guideline does not guarantee security, and it does not intend to limit the liberty to implement new analysis. However, it provides for the first time in the literature a solid basis about integral analysis for chaos-based image cryptosystems as an effective approach to improve security.

scholarly journals Beyond the labeled line: variation in visual reference frames from intraparietal cortex to frontal eye fields and the superior colliculus

2017 ◽  
Author(s):  
V. C. Caruso ◽  
D. S. Pages ◽  
M. A. Sommer ◽  
J. M. Groh
Keyword(s):  
Receptive Field ◽  
Superior Colliculus ◽  
Reference Frames ◽  
Receptive Fields ◽  
Visual Signals ◽  
Eye Position ◽  
Frontal Eye Fields ◽  
Response Patterns ◽  
The Stability ◽  
Retinal Information

ABSTRACTWe accurately perceive the visual scene despite moving our eyes ~3 times per second, an ability that requires incorporation of eye position and retinal information. We assessed how this neural computation unfolds across three interconnected structures: frontal eye fields (FEF), intraparietal cortex (LIP/MIP), and the superior colliculus (SC). Single unit activity was assessed in head-restrained monkeys performing visually-guided saccades from different initial fixations. As previously shown, the receptive fields of most LIP/MIP neurons shifted to novel positions on the retina for each eye position, and these locations were not clearly related to each other in either eye- or head-centered coordinates (hybrid coordinates). In contrast, the receptive fields of most SC neurons were stable in eye-centered coordinates. In FEF, visual signals were intermediate between those patterns: around 60% were eye-centered, whereas the remainder showed changes in receptive field location, boundaries, or responsiveness that rendered the response patterns hybrid or occasionally head-centered. These results suggest that FEF may act as a transitional step in an evolution of coordinates between LIP/MIP and SC. The persistence across cortical areas of hybrid representations that do not provide unequivocal location labels in a consistent reference frame has implications for how these representations must be read-out.New & NoteworthyHow we perceive the world as stable using mobile retinas is poorly understood. We compared the stability of visual receptive fields across different fixation positions in three visuomotor regions. Irregular changes in receptive field position were ubiquitous in intraparietal cortex, evident but less common in the frontal eye fields, and negligible in the superior colliculus (SC), where receptive fields shifted reliably across fixations. Only the SC provides a stable labelled-line code for stimuli across saccades.

scholarly journals An Alternative Theory on the Spacetime of Non-inertial Reference Frame

2017 ◽  
Vol 9 (5) ◽  
pp. 90
Author(s):  
Gordon Liu
Keyword(s):  
Reference Frame ◽  
Coordinate Transformation ◽  
Reference Frames ◽  
Inertial Force ◽  
Christoffel Symbol ◽  
Alternative Theory ◽  
Inertial Reference Frame ◽  
Riemann Curvature ◽  
Riemann Curvature Tensor ◽  
Accelerating Motion

In present paper, we have proposed an alternative theory on the spacetime of non-inertial reference frame (NRF) which bases on the requirement of general completeness (RGC) and the principle of equality of all reference frames (PERF). The RGC is that the physical equations used to describe the dynamics of matter and/or fields should include the descriptions that not only the matter and/or fields are at rest, but also they move relative to this reference frame, and the structure of the spacetime of reference frame has been considered. The PERF is that any reference frame can be used to describe the motion of matter and/or fields. The spacetime of NRF is inhomogeneous and deformed caused by the accelerating motion of the reference frame. The inertial force is the manifestation of deformed spacetime. The Riemann curvature tensor of the spacetime of NRF equals zero, but the Riemann-Christoffel symbol never vanishs no matter what coordinate system is selected in the NRF. The physical equations satisfied the RGC remain covariance under the coordinate transformation between the reference frames. Mach’s principle is incorrect. The problem of spacetime of NRF can be solved without considering gravitation.

scholarly journals Applying coordinate fixed Denavit–Hartenberg method to solve the workspace of drilling robot arm

2018 ◽  
Vol 15 (4) ◽  
pp. 172988141879328 ◽  
Author(s):  
Feng Ding ◽  
Cong Liu
Keyword(s):  
Coordinate Transformation ◽  
Kinematic Analysis ◽  
Robot Arm ◽  
Functional Requirements ◽  
Core Component ◽  
Actual Structure ◽  
The Core ◽  
Drilling Equipment ◽  
Intelligent Technology ◽  
First Time

Drilling robot is a piece of large rock drilling equipment that integrates mechanical, electrical, and hydraulic technique, and it is a significant device for drilling and blasting. The drilling robot arm is the core component of the robot. To get intuitive and accurate modeling method to overcome the problem of the classic Denavit–Hartenberg method, for instance, the model mismatches the entity. The coordinate system fixed on the entity of Denavit–Hartenberg notation that is named coordinate-fixed Denavit–Hartenberg is creatively presented. The coordinate-fixed Denavit–Hartenberg method not only improves the accuracy and operability of kinematic analysis but also solves the workspace of drilling robot arm effectively. The drilling robot from an intelligent technology company in China is taken as the research example in this article. The homogeneous coordinate transformation matrix of each link rod is established through reasonably simplifying drilling robot arm as a multijoint structure. The coordinate-fixed Denavit–Hartenberg method is utilized for the first time in determining and verifying the kinematics equation of drilling robot arm. The kinematics equation is employed to obtain the effective workspace of drilling robot arm. The analysis results demonstrate that the design of drilling robot arm reaches the need of workspace in the actual structure as well as meets the functional requirements of drilling robot.

Error Analysis and Compensation for Meshing Contact of Toroidal Drives

2005 ◽  
Vol 128 (3) ◽  
pp. 610-617 ◽  
Author(s):  
Ligang Yao ◽  
Jian S. Dai ◽  
Guowu Wei
Keyword(s):  
Error Analysis ◽  
Coordinate Transformation ◽  
New Method ◽  
Coordinate Frames ◽  
Oil Film ◽  
Typical Type ◽  
Gear Drives ◽  
First Time

This paper investigates the meshing errors of the toroidal drive, reveals three typical latency errors and develops the error analysis in this typical type of gear drives. Having identified the latency errors, the error integrated coordinate transformation is implemented. This leads to the development of the error impinged meshing model. The model reveals for the first time the effect of the latency errors in gear meshing contact of a toroidal drive and characterizes the error effect on meshing contact. The effect of these errors on the gear coordinate frames is hence presented and on the contact paths of rollers is analyzed. The study leads to a new method for compensating the three latency errors by introducing a bearing with a changeable oil film. The method is then verified in a prototype and demonstrates to be effective.

Hyperstriatum ventrale in pigeons: Effects of lesions on color-discrimination and color-reversal learning

1997 ◽  
Vol 14 (6) ◽  
pp. 1029-1041 ◽  
Author(s):  
Lin M. Chaves ◽  
William Hodos
Keyword(s):  
Reversal Learning ◽  
Visual Information ◽  
Original Learning ◽  
Color Discrimination ◽  
Visual Pathway ◽  
Visual Input ◽  
Impaired Performance ◽  
Nucleus Rotundus ◽  
Tectofugal Pathway ◽  
Hyperstriatum Ventrale

AbstractPrevious lesion studies of color-reversal learning in pigeons show that an impairment results when (1) the tectofugal visual pathway is damaged at either the thalamic level (nucleus rotundus) or the telencephalic level (ectostriatum), or (2) the thalamofugal visual pathway is damaged at the telencephalic level (the visual Wulst). An impairment does not result, however, when the thalamic source of thalamofugal input (n. opticus principalis thalami or OPT) to the visual Wulst is damaged. These results suggest that the visual Wulst plays a role in color-reversal learning as a consequence of visual information routed from the tectofugal pathway via other visual areas in the telencephalon. One such area is the hyperstriatum ventrale (HV). In the present study, after ablation of the medial and lateral regions of HV, pigeons were trained postoperatively to discriminate between two colors presented simultaneously. After reaching criterion, the pigeons were required to perform a series of discrimination reversals in which the positive and negative stimuli were interchanged. Lesions of medial HV resulted in impaired performance of a color-discrimination task (i.e. original learning), but did not affect discrimination reversal. An impairment in color-reversal learning resulted from combined damage to lateral HV and the fronto-thalamic tract (FT), which carries ascending visual input from OPT to the visual Wulst. No deficits were observed when either lateral HV or FT were damaged alone. These findings suggest that both the thalamofugal and tectofugal pathways provide the visual Wulst with visual input relevant to color-reversal learning.

scholarly journals Nutation and reference frame

1995 ◽  
Vol 10 ◽  
pp. 228-231
Author(s):  
N. Capitaine
Keyword(s):  
Perturbation Theory ◽  
Reference Frame ◽  
Euler Equations ◽  
Coordinate Transformation ◽  
Earth Rotation ◽  
Reference System ◽  
Reference Frames ◽  
Fundamental Importance ◽  
Terrestrial Reference System ◽  
Celestial Reference System

The reference frames are of fundamental importance in all kinds of the precession and nutation studies involving the theory, the coordinate transformation and the observations. The aim of this paper is to review all the frames used in such studies and to lead to a better consistency between them in order that theory and reductions of observations be referred, as close as possible, to the frames to which observables are actually sensitive.The equations of Earth rotation can be expressed either as Euler equations in the Terrestrial Reference System (TRS), or as perturbation theory in the Celestial Reference System (CRS) (Kinoshita 1977). Euler equations are transformed to the CRS in the astronomical approach (Woolard 1953) and solved by the method of variation of the parameters, whereas, in the geophysical approach (Melchior 1971), the solutions, first obtained in the TRS, are transformed to the CRS and then solved by an integration with respect to time.

scholarly journals Full gaze contingency provides better reading performance than head steering alone in a simulation of prosthetic vision

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nadia Paraskevoudi ◽  
John S. Pezaris
Keyword(s):  
Visual Acuity ◽  
Eye Movements ◽  
Patient Outcomes ◽  
Visual Pathway ◽  
Reading Performance ◽  
Artificial Vision ◽  
Eye Position ◽  
Font Size ◽  
Normal Speed ◽  
Gaze Position

AbstractThe visual pathway is retinotopically organized and sensitive to gaze position, leading us to hypothesize that subjects using visual prostheses incorporating eye position would perform better on perceptual tasks than with devices that are merely head-steered. We had sighted subjects read sentences from the MNREAD corpus through a simulation of artificial vision under conditions of full gaze compensation, and head-steered viewing. With 2000 simulated phosphenes, subjects (n = 23) were immediately able to read under full gaze compensation and were assessed at an equivalent visual acuity of 1.0 logMAR, but were nearly unable to perform the task under head-steered viewing. At the largest font size tested, 1.4 logMAR, subjects read at 59 WPM (50% of normal speed) with 100% accuracy under the full-gaze condition, but at 0.7 WPM (under 1% of normal) with below 15% accuracy under head-steering. We conclude that gaze-compensated prostheses are likely to produce considerably better patient outcomes than those not incorporating eye movements.

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