The effects of visual input on open-loop and closed-loop postural control mechanisms

1995 ◽  
Vol 103 (1) ◽  
pp. 151-163 ◽  
Author(s):  
J. J. Collins ◽  
C. J. De Luca
Keyword(s):  
Postural Control ◽  
Closed Loop ◽  
Open Loop ◽  
Visual Input ◽  
Control Mechanisms

The effects of spaceflight on open-loop and closed-loop postural control mechanisms: human neurovestibular studies on SLS-2

1995 ◽  
Vol 107 (1) ◽  
pp. 145-150 ◽  
Author(s):  
J. J. Collins ◽  
C. J. De Luca ◽  
A. E. Pavlik ◽  
S. H. Roy ◽  
M. S. Emley
Keyword(s):  
Postural Control ◽  
Closed Loop ◽  
Open Loop ◽  
Control Mechanisms

Age-related changes in open-loop and closed-loop postural control mechanisms

1995 ◽  
Vol 104 (3) ◽  
pp. 480-492 ◽  
Author(s):  
J. J. Collins ◽  
C. J. De Luca ◽  
A. Burrows ◽  
L. A. Lipsitz
Keyword(s):  
Postural Control ◽  
Closed Loop ◽  
Open Loop ◽  
Control Mechanisms ◽  
Age Related ◽  
Age Related Changes

scholarly journals Closed loop motor-sensory dynamics in human vision

2019 ◽  
Author(s):  
Liron Gruber ◽  
Ehud Ahissar
Keyword(s):  
Eye Movements ◽  
Visual Processing ◽  
Closed Loop ◽  
Open Loop ◽  
Visual Input ◽  
Human Vision ◽  
Visual Inputs ◽  
Eye Motion ◽  
Slow Eye Movements ◽  
The Brain

AbstractVision is obtained with a continuous motion of the eyes. The kinematic analysis of eye motion, during any visual or ocular task, typically reveals two (kinematic) components: saccades, which quickly replace the visual content in the retinal fovea, and drifts, which slowly scan the image after each saccade. While the saccadic exchange of regions of interest (ROIs) is commonly considered to be included in motor-sensory closed-loops, it is commonly assumed that drifts function in an open-loop manner, that is, independent of the concurrent visual input. Accordingly, visual perception is assumed to be based on a sequence of open-loop processes, each initiated by a saccade-triggered retinal snapshot. Here we directly challenged this assumption by testing the dependency of drift kinematics on concurrent visual inputs using real-time gaze-contingent-display. Our results demonstrate a dependency of the trajectory on the concurrent visual input, convergence of speed to condition-specific values and maintenance of selected drift-related motor-sensory controlled variables, all strongly indicative of drifts being included in a closed-loop brain-world process, and thus suggesting that vision is inherently a closed-loop process.Author summaryOur eyes do not function like cameras; it has long been known that we are actively scanning our visual environment in order to see. Moreover, it is commonly accepted that our fast eye movements, saccades, are controlled by the brain and are affected by the sensory input. However, our slow eye movements, the ocular drifts, are often ignored when visual acquisition is analyzed. Accordingly, visual processing is typically assumed to be based on computations performed on saccade-triggered snapshots of the retinal state. Our work strongly challenges this model and provides significant evidence for an alternative model, a cybernetic one. We show that the dynamics of the ocular drifts do not allow, and cannot be explained by, open loop visual acquisition. Instead, our results suggest that visual acquisition is part of a closed-loop process, which dynamically and continuously links the brain to its environment.

Acute Effects of a Single Bout of Resistance Exercise on Postural Control in Elderly Persons

2005 ◽  
Vol 100 (3) ◽  
pp. 725-733 ◽  
Author(s):  
Justin B. Moore ◽  
Thomas Korff ◽  
Stephen J. Kinzey
Keyword(s):  
Resistance Training ◽  
Postural Control ◽  
Resistance Exercise ◽  
Critical Point ◽  
Center Of Pressure ◽  
Open Loop ◽  
Elderly Persons ◽  
Control Mechanisms ◽  
Acute Effects ◽  
Loop Control

Many elderly persons are engaging in resistance exercise to counter muscle atrophy due to aging. Here, the acute effects of resistance exercise on postural control mechanisms were examined. Postural control was quantified by mean square center-of-pressure displacements were calculated utilizing force vectors in accordance with previously developed equations. Stabilogram-diffusion plots utilized the displacements as data points after curve-fitting techniques were applied. Two regions, representing the open-loop and closed-loop postural control mechanisms, are shown by the plots and separated at the critical point, which represents the shift in control mechanisms. 21 older adults (age M = 71.2, SD = 3.84, range 66–81 years) performed three sets of 10–12 repetitions for six resistance exercises for the lower extremity until fatigue. Immediately after exercise, postural stability was reduced. This was represented by a shift of the critical point to the right, indicating an increase in open-loop control. Since resistance training has an acute negative effect on postural control, it is advised to assist elderly clients carefully and immediately after resistance training.

scholarly journals Influences of Frailty Syndrome on Open-Loop and Closed-Loop Postural Control Strategy

Gerontology ◽  
2015 ◽  
Vol 61 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Nima Toosizadeh ◽  
Jane Mohler ◽  
Christopher Wendel ◽  
Bijan Najafi
Keyword(s):  
Postural Control ◽  
Control Strategy ◽  
Closed Loop ◽  
Open Loop ◽  
Frailty Syndrome ◽  
Postural Control Strategy

The Impact of Visual Feedback Type on the Mastery of Visuo-Motor Transformations

2012 ◽  
Vol 220 (1) ◽  
pp. 3-9 ◽  
Author(s):  
Sandra Sülzenbrück
Keyword(s):  
Empirical Research ◽  
Visual Feedback ◽  
Closed Loop ◽  
Motor Planning ◽  
Visual Input ◽  
Closed Loop Control ◽  
Loop Control ◽  
Feedback Type ◽  
Effective Use ◽  
The Impact

For the effective use of modern tools, the inherent visuo-motor transformation needs to be mastered. The successful adjustment to and learning of these transformations crucially depends on practice conditions, particularly on the type of visual feedback during practice. Here, a review about empirical research exploring the influence of continuous and terminal visual feedback during practice on the mastery of visuo-motor transformations is provided. Two studies investigating the impact of the type of visual feedback on either direction-dependent visuo-motor gains or the complex visuo-motor transformation of a virtual two-sided lever are presented in more detail. The findings of these studies indicate that the continuous availability of visual feedback supports performance when closed-loop control is possible, but impairs performance when visual input is no longer available. Different approaches to explain these performance differences due to the type of visual feedback during practice are considered. For example, these differences could reflect a process of re-optimization of motor planning in a novel environment or represent effects of the specificity of practice. Furthermore, differences in the allocation of attention during movements with terminal and continuous visual feedback could account for the observed differences.

On closed-loop equilibrium strategies for mean-field stochastic linear quadratic problems

2020 ◽  
Vol 26 ◽  
pp. 41
Author(s):  
Tianxiao Wang
Keyword(s):  
Optimal Control ◽  
Closed Loop ◽  
Optimal Control Problems ◽  
Mean Field ◽  
Open Loop ◽  
Time Inconsistency ◽  
Control Problems ◽  
Linear Quadratic ◽  
Linear Quadratic Optimal Control ◽  
Equilibrium Strategies

This article is concerned with linear quadratic optimal control problems of mean-field stochastic differential equations (MF-SDE) with deterministic coefficients. To treat the time inconsistency of the optimal control problems, linear closed-loop equilibrium strategies are introduced and characterized by variational approach. Our developed methodology drops the delicate convergence procedures in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. When the MF-SDE reduces to SDE, our Riccati system coincides with the analogue in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. However, these two systems are in general different from each other due to the conditional mean-field terms in the MF-SDE. Eventually, the comparisons with pre-committed optimal strategies, open-loop equilibrium strategies are given in details.

Comparison of Dc-Dc SEPIC, CUK and Flyback Converters Based LED Drivers

2020 ◽  
pp. 99-107
Author(s):  
Erdal Sehirli
Keyword(s):  
Integrated Circuit ◽  
Closed Loop ◽  
Input Voltage ◽  
Open Loop ◽  
Current Sensor ◽  
Switching Frequency ◽  
Led Driver ◽  
Advantages And Disadvantages ◽  
Led Drivers ◽  
Conduction Mode

This paper presents the comparison of LED driver topologies that include SEPIC, CUK and FLYBACK DC-DC converters. Both topologies are designed for 8W power and operated in discontinuous conduction mode (DCM) with 88 kHz switching frequency. Furthermore, inductors of SEPIC and CUK converters are wounded as coupled. Applications are realized by using SG3524 integrated circuit for open loop and PIC16F877 microcontroller for closed loop. Besides, ACS712 current sensor used to limit maximum LED current for closed loop applications. Finally, SEPIC, CUK and FLYBACK DC-DC LED drivers are compared with respect to LED current, LED voltage, input voltage and current. Also, advantages and disadvantages of all topologies are concluded.

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