Linear versus non-linear measures of temporal variability in finger tapping and their relation to performance on open- versus closed-loop motor tasks: Comparing standard deviations to Lyapunov exponents

2008 ◽  
Vol 13 (3) ◽  
pp. 255-281 ◽  
Author(s):  
Stephen D. Christman ◽  
Ryan Weaver
Keyword(s):  
Lyapunov Exponents ◽  
Temporal Variability ◽  
Closed Loop ◽  
Finger Tapping ◽  
Motor Tasks ◽  
Non Linear ◽  
Standard Deviations ◽  
Open Versus

Sleep and motor learning

2020 ◽  
pp. 12-19
Author(s):  
Antonio Cicchella
Keyword(s):  
Motor Learning ◽  
Experimental Research ◽  
Human Body ◽  
Learning Process ◽  
Finger Tapping ◽  
Historical Overview ◽  
Motor Tasks ◽  
Sleep Habits ◽  
Simple Motor ◽  
Function Of Sleep

Sleep is a process, which happens in human body and has many functions. One relatively recently studied function of sleep is its involvement in the motor learning process. This paper presents a historical overview of the studies on sleep, and the results of two experimental research studies that explore the motor learning of a simple finger tapping tasks performed by adults, and the sleep habits of boys practicing sports. The research results show that sleep has an effect on improving motion retention of simple motor tasks, and that sports improve sleep for boys, thus contributing to better learning.

Cognitive-motor interference in persons with multiple sclerosis during five upper limb motor tasks with different complexity

2018 ◽  
Vol 25 (13) ◽  
pp. 1736-1745 ◽  
Author(s):  
Joke Raats ◽  
Ilse Lamers ◽  
Ilse Baert ◽  
Barbara Willekens ◽  
Renee Veldkamp ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Upper Limb ◽  
Test Group ◽  
Word List ◽  
Finger Tapping ◽  
Motor Tasks ◽  
Generation Task ◽  
Bimanual Task ◽  
Finger Tapping Test ◽  
Block Test

Background: Cognitive-motor interference in multiple sclerosis has been well examined during walking, but not during upper limb (UL) performance. Objectives: To examine the dual-task cost (DTC) in persons with multiple sclerosis (pwMS) and healthy controls (HC) in various type and complexity of UL motor tasks. Method: In total, 30 pwMS without major UL impairment and 30 HC performed five different UL tasks, in single condition and combined with the phonemic word list generation task. The percent change in performances was evaluated by the motor, cognitive, and combined DTC. The motor tasks consisted of four unimanual (sustained hand grip strength, box-and-block test, Purdue pegboard test, finger tapping task) and one bimanual task (Purdue pegboard test). Group and task differences were analyzed with unpaired and paired t-tests, respectively, and overall effect with a multivariate analysis of variance. Results: The motor DTC ranged between 10% (Purdue pegboard bimanual) and 35% (box-and-block test). The cognitive DTC ranged between −8% (finger tapping test) and +21% (bimanual Purdue pegboard). The magnitude of the combined DTC did not differ significantly between pwMS and HC in any task. Conclusion: DTC is influenced by the complexity of the UL task, but was not significantly different between HC and cognitive intact, but mildly motor disabled pwMS.

Design of H_/H∞ fault detection observer for closed-loop nonlinear system with disturbance

2020 ◽  
Vol 40 (4) ◽  
pp. 589-599
Author(s):  
Zhengquan Chen ◽  
Lu Han ◽  
Yandong Hou
Keyword(s):  
Fault Detection ◽  
Closed Loop ◽  
External Disturbance ◽  
Adaptive Threshold ◽  
Linear Matrix ◽  
Content Type ◽  
Non Linear ◽  
Runge Kutta ◽  
Non Linear System ◽  
Residual Generator

Purpose This paper proposes a novel method of fault detection, which is based on H_/H∞ Runge–Kutta observer and an adaptive threshold for a class of closed-loop non-linear systems. The purpose of this paper is to improve the rapidity and accuracy of fault detection. Design/methodology/approach First, the authors design the H_/H∞ Runge–Kutta fault detection observer, which is used as a residual generator to decouple the residual from the input. The H_ performance index metric in the specified frequency domain is used to describe how sensitive the residual to the fault. The H∞ norm is used to describe the residual robustness to the external disturbance of the systems. The residual generator is designed to achieve the best tradeoff between robustness against unknown disturbances but sensitivity to faults, thus realizing the accurate detection of the fault by suppressing the influence of noise and disturbance on the residual. Next, the design of the H_/H∞ fault detection observer is transformed into a convex optimization problem and solved by linear matrix inequality. Then, a new adaptive threshold is designed to improve the accuracy of fault detection. Findings The effectiveness and correctness of the method are tested in simulation experiments. Originality/value This paper presents a novel approach to improve the accuracy and rapidity of fault detection for closed-loop non-linear system with disturbances and noise.

Assessing multiple muscle activation during squat movements with different loading conditions – an EMG study

2018 ◽  
Vol 63 (4) ◽  
pp. 413-420
Author(s):  
Amir Pourmoghaddam ◽  
Marius Dettmer ◽  
Stefany J.K. Malanka ◽  
Mitchell Veverka ◽  
Daniel P. O’Connor ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
Linear Analysis ◽  
Clinical Diagnostics ◽  
Analysis Tool ◽  
Loading Conditions ◽  
Motor Tasks ◽  
Cyclic Movements ◽  
Non Linear ◽  
Clinical Environments

Abstract Surface electromyography (EMG) is a valuable tool in clinical diagnostics and research related to human neuromotor control. Non-linear analysis of EMG data can help with detection of subtle changes of control due to changes of external or internal constraints during motor tasks. However, non-linear analysis is complex and results may be difficult to interpret, particularly in clinical environments. We developed a non-linear analysis tool (SYNERGOS) that evaluates multiple muscle activation (MMA) features and provides a single value for description of activation characteristics. To investigate the responsiveness of SYNERGOS to kinetic changes during cyclic movements, 13 healthy young adults performed squat movements under different loading conditions (100%–120% of body weight). We processed EMG data to generate SYNERGOS indices and used two-way repeated measures ANOVA to determine changes of MMA in response to loading conditions during movement. SYNERGOS values were significantly different for each loading condition. We concluded that the algorithm is sensitive to kinetic changes during cyclic movements, which may have implications for applications in a variety of experimental and diagnostic settings.

scholarly journals The transient variation in the complexes of the low-latitude ionosphere within the equatorial ionization anomaly region of Nigeria

2015 ◽  
Vol 22 (5) ◽  
pp. 527-543 ◽  
Author(s):  
A. B. Rabiu ◽  
B. O. Ogunsua ◽  
I. A. Fuwape ◽  
J. A. Laoye
Keyword(s):  
Time Series ◽  
Lyapunov Exponent ◽  
Lyapunov Exponents ◽  
Correlation Dimension ◽  
Tsallis Entropy ◽  
Variation Pattern ◽  
Dynamical Complexity ◽  
Equatorial Ionization Anomaly ◽  
Non Linear ◽  
Anomaly Region

Abstract. The quest to find an index for proper characterization and description of the dynamical response of the ionosphere to external influences and its various internal irregularities has led to the study of the day-to-day variations of the chaoticity and dynamical complexity of the ionosphere. This study was conducted using Global Positioning System (GPS) total electron content (TEC) time series, measured in the year 2011, from five GPS receiver stations in Nigeria, which lies within the equatorial ionization anomaly region. The non-linear aspects of the TEC time series were obtained by detrending the data. The detrended TEC time series were subjected to various analyses to obtain the phase space reconstruction and to compute the chaotic quantifiers, which are Lyapunov exponents LE, correlation dimension, and Tsallis entropy, for the study of dynamical complexity. Considering all the days of the year, the daily/transient variations show no definite pattern for each month, but day-to-day values of Lyapunov exponents for the entire year show a wavelike semiannual variation pattern with lower values around March, April, September and October. This can be seen from the correlation dimension with values between 2.7 and 3.2, with lower values occurring mostly during storm periods, demonstrating a phase transition from higher dimension during the quiet periods to lower dimension during storms for most of the stations. The values of Tsallis entropy show a similar variation pattern to that of the Lyapunov exponent, with both quantifiers correlating within the range of 0.79 to 0.82. These results show that both quantifiers can be further used together as indices in the study of the variations of the dynamical complexity of the ionosphere. The presence of chaos and high variations in the dynamical complexity, even in quiet periods in the ionosphere, may be due to the internal dynamics and inherent irregularities of the ionosphere which exhibit non-linear properties. However, this inherent dynamics may be complicated by external factors like geomagnetic storms. This may be the main reason for the drop in the values of the Lyapunov exponent and Tsallis entropy during storms. The dynamical behaviour of the ionosphere throughout the year, as described by these quantifiers, was discussed in this work.

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