scholarly journals The Roles of CPG Phase Modulation and Reflexive Muscular Patterns in Balance Recovery During Walking—A Simulation Study

2008 ◽  
Vol 5 (1) ◽  
pp. 1-11
Author(s):  
Yu Ikemoto ◽  
Wenwei Yu
Keyword(s):  
Motor Control ◽  
Simulation Study ◽  
Real World ◽  
Phase Modulation ◽  
Response Patterns ◽  
Stability Criteria ◽  
Simulation Experiments ◽  
Uneven Terrain ◽  
Short Period ◽  
Muscle Responses

Most walking assist systems reported are not available for real world environments where frequent perturbations are caused by slips, uneven terrain, slopes and obstacles. It is evident that humans are able to cope with such perturbations with reflexes that cause unconscious, relatively fixed muscular response patterns to perturbations within a short period of time. In our previous study, we showed that artificial reflexes could improve the perturbation resistance for simulated walkers, though the roles of different reflexive mechanisms were not quantitatively clarified. In this study, we focused on the different roles of reflexive muscle responses and the CPG phase modulation mechanism. By proposing and evaluating two stability criteria through a series of simulation experiments, we revealed different roles for two mechanisms in the simulated walkers. These will not only further increase the possibility of realising artificial reflexes for paralysed individuals, but also bring new insights into the field of motor control.

HUMAN REFLEXIVE RESPONSE AND ITS OBJECTIVE FUNCTION REGARDING BALANCE RECOVERY FROM PERTURBATION DURING WALKING

2011 ◽  
Vol 11 (05) ◽  
pp. 1179-1198 ◽  
Author(s):  
YU YIKEMOTO ◽  
WENWEI YU ◽  
U. RAJENDRA ACHARYA
Keyword(s):  
Underlying Mechanism ◽  
Living Environment ◽  
Neural Mechanisms ◽  
Unified Theory ◽  
Response Patterns ◽  
Objective Functions ◽  
Balance Recovery ◽  
Uneven Terrain ◽  
Short Period ◽  
Evaluation Measure

Balance recovery from perturbation plays a crucial role in preventing people from falling during walking. Understanding the underlying mechanism of balance recovery during walking could not only bring new insights into the motor control field, but also benefit the development of walking assist systems for daily living environment, where perturbations to walking are frequently caused by slips, uneven terrain, slopes, obstacles, etc.It is evident that humans can cope with such perturbations, especially when the perturbations cannot be predicted or perceived in advance, by means of reflexes, which cause relatively fixed, unconscious muscular response patterns to perturbations within a short period of time ranging from several tens of ms to 200 ms. However, except for several hypotheses about the underlying neural mechanisms of the reflexes during walking, there is no widely accepted unified theory.In our previous study, a muscular-reflexive pattern was defined using muscle activity recorded during reflexive responses to slip perturbation. This is one important step toward the understanding of the underlying mechanism, since the pattern could serve as the quantitative target in pursuit of the underlying mechanism. We can speculate that this pattern is the optimal balance recovery behavior to human muscular-skeletal system, as a result of long evolution; however, before we use this target to guide our pursuit, we should first prove its optimality, while making clear the objective functions for balance recovery and the effect of morphological factors.Our approach includes (1) defining objective functions for balance recovery from a slip perturbation during walking; (2) using a bio-mimetic human walking simulator to perform evaluation according to the objective functions; (3) employing a genetic algorithm (GA) to search the optimal solutions, for different objective functions.Results showed that the muscular-reflexive pattern is optimal to the balance recovery from slip perturbation during walking, in terms of a hybrid evaluation measure (HEM), which takes both static and dynamic aspects of balance recovery into consideration.

scholarly journals Multiple imputation for systematically missing confounders within a distributed data drug safety network: A simulation study and real‐world example

2019 ◽  
Vol 29 (S1) ◽  
pp. 35-44 ◽  
Author(s):  
Matthew H. Secrest ◽  
Robert W. Platt ◽  
Pauline Reynier ◽  
Colin R. Dormuth ◽  
Andrea Benedetti ◽  
...  
Keyword(s):  
Multiple Imputation ◽  
Drug Safety ◽  
Simulation Study ◽  
Real World ◽  
Distributed Data

Measurement and Interpretation of Driver/Vehicle System Dynamic Response

1973 ◽  
Vol 15 (4) ◽  
pp. 367-378 ◽  
Author(s):  
David H. Weir ◽  
Duane T. McRuer
Keyword(s):  
Dynamic Response ◽  
Real World ◽  
Experimental Verification ◽  
Closed Loop ◽  
Lateral Position ◽  
Visual Simulation ◽  
Simulation Experiments ◽  
Describing Functions ◽  
Vehicle System ◽  
Directional Control

This paper summarizes applicable theory and data from simulation experiments on the directional control of automobiles subjected to crosswind gust disturbances. Measured driver/vehicle describing functions for several subjects and replications are presented and interpreted. It is shown that the driver's steering outputs can be explained as functions of lateral position and heading, although alternate interpretations involving path-angle and path-rate feedbacks are considered. The results demonstrate that driver/vehicle response properties can be modeled and measured for a class of important closed-loop driving tasks. They provide further direct experimental verification of the applicability of driver/vehicle theory to situations where the driver obtains his information from a real-world visual simulation.

The Stability of the Short-Period Motion of an Airframe Having Non-Linear Normal Force and Pitching Moment Curves

1960 ◽  
Vol 11 (3) ◽  
pp. 255-268
Author(s):  
P. A. T. Christopher
Keyword(s):  
Stability Theory ◽  
Phase Plane ◽  
Normal Force ◽  
Pitching Moment ◽  
Stability Criteria ◽  
Short Period ◽  
Non Linear ◽  
Non Linear Systems ◽  
The Stability ◽  
Period Motion

SummaryThe analysis of the stability of second-order non-linear systems by Poincare's method of singular points in the phase plane is briefly presented and used to determine stability criteria for the short-period motion of an airframe having non-linear normal force and pitching moment curves. These results are then compared with those obtained by the application of quasilinear stability theory.

Engendering Bilateralism: An Exploration of Possible Sources of Non-Centrism in Government Formation

2017 ◽  
Vol 7 (04) ◽  
pp. 699-715 ◽  
Author(s):  
Paul V. Warwick
Keyword(s):  
Real World ◽  
Policy Space ◽  
Simulation Experiments ◽  
Government Formation ◽  
Policy Positions ◽  
The Real ◽  
Potential Impact

This paper seeks to identify factors that may lie behind the tendency for parliamentary governments to form primarily from one side of the left-right spectrum and to adopt non-centrist policy positions. Because of measurement limitations as well as the inherent complexity of the processes involved, this exploration is undertaken through simulation experiments. The new software created for these experiments allows the potential impact of a wide variety of factors, including voter and party motivations and distributions, policy space dimensionality, and constraints on government formation, to be assessed. Although the results cannot tell us what fosters non-centrism in the real world, they do reveal some factors that appear to be conducive to that end and thus serve as a guide to further research on this neglected topic.

scholarly journals A shared numerical representation for action and perception

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Giovanni Anobile ◽  
Roberto Arrighi ◽  
Irene Togoli ◽  
David Charles Burr
Keyword(s):  
Magnitude Estimation ◽  
Real World ◽  
Sensory Feedback ◽  
Perception And Action ◽  
Visual Stimuli ◽  
Finger Tapping ◽  
Numerical Representation ◽  
Short Period ◽  
Action And Perception ◽  
External Events

Humans and other species have perceptual mechanisms dedicated to estimating approximate quantity: a sense of number. Here we show a clear interaction between self-produced actions and the perceived numerosity of subsequent visual stimuli. A short period of rapid finger-tapping (without sensory feedback) caused subjects to underestimate the number of visual stimuli presented near the tapping region; and a period of slow tapping caused overestimation. The distortions occurred both for stimuli presented sequentially (series of flashes) and simultaneously (clouds of dots); both for magnitude estimation and forced-choice comparison. The adaptation was spatially selective, primarily in external, real-world coordinates. Our results sit well with studies reporting links between perception and action, showing that vision and action share mechanisms that encode numbers: a generalized number sense, which estimates the number of self-generated as well as external events.

scholarly journals How non-veridical perception drives actions in healthy humans - Evidence from Synaesthesia

2018 ◽  
Author(s):  
Marie Luise Schreiter ◽  
Witold X. Chmielewski ◽  
Jamie Ward ◽  
Christian Beste
Keyword(s):  
Motor Control ◽  
Real World ◽  
Underlying Mechanism ◽  
Veridical Perception ◽  
Healthy Human ◽  
Healthy Humans ◽  
Model Condition ◽  
Clinical Conditions ◽  
Influence Behavior ◽  
Perception Action

AbstractWe continually perform actions driven by our perception and it is commonly held that only objectively perceived changes within the ‘real’ world affect behaviour. Exceptions are usually only made for clinical conditions associated with hallucinations, where objectively non-existent percepts can influence behavior. Using synaesthesia as a model condition, we show that even in healthy populations irrelevant non-veridical precepts exert an effect on action. By non-veridical we refer to stimulus dimensions that are only subjectively perceived to be there. Applying electrophysiological (EEG) methods, we show that although these examined peculiarities are perceptual in nature, not primarily perceptual processes underlie the effects of irrelevant non-veridical perceptions on actions. Rather, high-order processes linking perceptions and motor control in medial frontal cortices reflect the underlying mechanism how irrelevant non-veridical perceptions modulate behaviour. Our results challenge assumptions about the determinants of healthy human behaviour but can be embedded within existing frameworks detailing perception action interactions.

scholarly journals Power converters for three phase electric locomotives

2021 ◽  
Vol 5 (S2) ◽  
pp. 1083-1092
Author(s):  
H. Suresh ◽  
A. M. Vaibhav ◽  
H. N. Suresh
Keyword(s):  
Analytical Model ◽  
Simulation Study ◽  
Real World ◽  
Power Converters ◽  
System Simulation ◽  
Abstract System ◽  
Matlab Simulink ◽  
Three Phase ◽  
And Behavior

This paper is about the simulation study of auxiliary converters used in 6000 HP electric locomotives used in India. Simulation is a mirror of the operation of a real-world method or system. The process of simulating a system first requires that a model be designed. This model represents the key behaviors, characteristics, and functions of the selected physical or abstract system. It helps to analyze the behavior of the system without even building it. The results obtained are accurate in general when compared to the analytical model. It also helps to find unexpected errors and behavior of the system. Simulation is easy to perform “What-If” analysis. For this purpose, MATLAB/Simulink was used.

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