scholarly journals Smooth enlargement of human standing sway by instability due to weak reaction floor and noise

2016 ◽  
Vol 3 (1) ◽  
pp. 150570 ◽  
Author(s):  
Tetsuro Funato ◽  
Shinya Aoi ◽  
Nozomi Tomita ◽  
Kazuo Tsuchiya
Keyword(s):  
Nonlinear Control ◽  
Neurological Disorders ◽  
System Model ◽  
Quiet Standing ◽  
Body Sway ◽  
Intermittent Control ◽  
Dynamic Reaction ◽  
Weak Reaction ◽  
Integral Control ◽  
The Stability

Human quiet standing is accompanied by body sway. The amplitude of this body sway is known to be larger than would be predicted from simple noise effects, and sway characteristics are changed by neurological disorders. This large sway is thought to arise from nonlinear control with prolonged periods of no control (intermittent control), and a nonlinear control system of this kind has been predicted to exhibit bifurcation. The presence of stability-dependent transition enables dynamic reaction that depends on the stability of the environment, and can explain the change in sway characteristics that accompanies some neurological disorders. This research analyses the characteristics of a system model that induces transition, and discusses whether human standing reflects such a mechanism. In mathematical analysis of system models, (intermittent control-like) nonlinear control with integral control is shown to exhibit Hopf bifurcation. Moreover, from the analytical solution of the system model with noise, noise is shown to work to smooth the enlargement of sway around the bifurcation point. This solution is compared with measured human standing sway on floors with different stabilities. By quantitatively comparing the control parameters between human observation and model prediction, enlargement of sway is shown to appear as predicted by the model analysis.

scholarly journals Analysis of the stability of multi-mode systems with approximating nonlinear control laws

2021 ◽  
Vol 872 (1) ◽  
pp. 012010
Author(s):  
E A Shakhray ◽  
E V Lubentsova ◽  
V F Lubentsov ◽  
M V Meflekh
Keyword(s):  
Nonlinear Control ◽  
Control Laws ◽  
The Stability ◽  
Multi Mode

Bounded stability of the quiet standing posture: An intermittent control model

2008 ◽  
Vol 27 (3) ◽  
pp. 473-495 ◽  
Author(s):  
Alessandra Bottaro ◽  
Youko Yasutake ◽  
Taishin Nomura ◽  
Maura Casadio ◽  
Pietro Morasso
Keyword(s):  
Control Model ◽  
Quiet Standing ◽  
Intermittent Control ◽  
Standing Posture

Prolonged Standing Task Affects Adaptability of Postural Control in People With Parkinson’s Disease

2020 ◽  
Vol 35 (1) ◽  
pp. 58-67
Author(s):  
Gabriel Felipe Moretto ◽  
Felipe Balistieri Santinelli ◽  
Tiago Penedo ◽  
Luis Mochizuki ◽  
Natalia Madalena Rinaldi ◽  
...  
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Control System ◽  
Postural Control ◽  
The Body ◽  
Quiet Standing ◽  
Body Sway ◽  
Control Group ◽  
Postural Control System ◽  
Prolonged Standing

Background Studies on short-term upright quiet standing tasks have presented contradictory findings about postural control in people with Parkinson’s disease (pwPD). Prolonged trial durations might better depict body sway and discriminate pwPD and controls. Objective The aim of this study was to investigate postural control in pwPD during a prolonged standing task. Methods A total of 26 pwPD and 25 neurologically healthy individuals performed 3 quiet standing trials (60 s) before completing a constrained prolonged standing task for 15 minutes. Motion capture was used to record body sway (Vicon, 100 Hz). To investigate the body sway behavior during the 15 minutes of standing, the analysis was divided into three 5-minute-long phases: early, middle, and late. The following body sway parameters were calculated for the anterior-posterior (AP) and medial-lateral (ML) directions: velocity, root-mean-square, and detrended fluctuations analysis (DFA). The body sway area was also calculated. Two-way ANOVAs (group and phases) and 1-way ANOVA (group) were used to compare these parameters for the prolonged standing and quiet standing, respectively. Results pwPD presented smaller sway area ( P < .001), less complexity (DFA; AP: P < .009; ML: P < .01), and faster velocity (AP: P < .002; ML: P < .001) of body sway compared with the control group during the prolonged standing task. Although the groups swayed similarly (no difference for sway area) during quiet standing, they presented differences in sway area during the prolonged standing task ( P < .001). Conclusions Prolonged standing task reduced adaptability of the postural control system in pwPD. In addition, the prolonged standing task may better analyze the adaptability of the postural control system in pwPD.

Dynamical properties about ultrasonic vibration assisted drilling of TiBw/TC4 composite

2020 ◽  
pp. 095440542096843
Author(s):  
Yong Feng ◽  
Haoxiang Wang ◽  
Min Zhang ◽  
Zihao Zhu ◽  
Xiaoyu Wang ◽  
...  
Keyword(s):  
Ultrasonic Vibration ◽  
Cutting Tools ◽  
System Model ◽  
Force Model ◽  
Drilling Process ◽  
Drilling Force ◽  
Dry Cutting ◽  
Analysis System ◽  
The Stability ◽  
Three Degree Of Freedom

TiBw / TC4 composite material was used as the machining object of Ultrasonic vibration assisted drilling (UVAD), the single directional three-degree-of-freedom dynamical system model was established. The dynamic signal test and analysis system was used for modal experiment to identify the parameters in the model. Under the condition of dry cutting, the drilling axial force and tool vibration in the drilling process are studied. The results showed that the maximum values of the predicted and measured axial drilling force were 412.5N and 439.6N respectively, and the error rate was 6.165%, which verified the reliability of the predicted axial drilling force model. For cutting tools, the average amplitudes of simulated vibration and measured vibration were 0.1124mm and 0.1151mm respectively, with a difference of 2.402%, and the overall trends were the same, which verifies the reliability of the dynamical model. Finally, the stability of drilling process was analyzed, and the frequency and amplitude of ultrasonic vibration were analyzed. The results show that in order to expand the unconditional stability region, it is more efficient to increase the amplitude than to increase the frequency.

THE EFFECTS OF DRESS SHOES ON STABILITY DURING QUIET STANDING AND ENERGY CONSUMPTION WHILE WALKING

2012 ◽  
Vol 12 (05) ◽  
pp. 1250029
Author(s):  
SAED MOHSEN MIRBOD ◽  
MOHAMMAD TAGHI KARIMI ◽  
A. ESHRAGHI
Keyword(s):  
Energy Consumption ◽  
Center Of Pressure ◽  
Force Plate ◽  
Normal Subjects ◽  
Quiet Standing ◽  
P Value ◽  
Cost Index ◽  
Mean Values ◽  
Physiological Cost ◽  
The Stability

Footwear is an extremely important clothing item worn by all individuals. Currently, there is insufficient research regarding the influence of dress shoes on standing stability and energy consumption while walking. Therefore, the aim of this study was to evaluate the influence of dress shoes on the performance of normal subjects based on stability and energy consumption analysis. Fifteen normal subjects were recruited in this research study to stand and walk with and without shoes. The stability of the subjects in quiet standing was measured by the use of a force plate based on center of pressure (COP) sway. The energy consumption was evaluated by a heart rate monitoring system (Polar Electro) based on the physiological cost index (PCI). The mean values of PCI while walking with and without shoes were 0.29 ± 0.117 and 0.265 ± 0.112 beats/m, respectively (p-value > 0.05). The amplitudes of COP sways in the mediolateral and anteroposterior directions were 10.4 ± 3.5 and 25 ± 6.92 mm while standing with shoes and 9.3 ± 2.84 and 22.5 ± 5.25 mm in barefoot standing, respectively (p-value > 0.05). It can be concluded that wearing dress shoes does not influence the performance of subjects while standing or walking.

scholarly journals Stability of PDF Controller With Stick-Slip Friction Device

1997 ◽  
Vol 119 (3) ◽  
pp. 486-490 ◽  
Author(s):  
Jia-Yush Yen ◽  
Chih-Jung Huang ◽  
Shu-Shung Lu
Keyword(s):  
Control Algorithm ◽  
Controller Design ◽  
System Model ◽  
Pole Placement ◽  
Order System ◽  
Stick Slip ◽  
Precision Control ◽  
Experimental Works ◽  
The Stability ◽  
Control Accuracy

This paper presents the precision control of drive devices with significant stick-slip friction. The controller design follows the Pseudo-Derivative Feedback (PDF) control algorithm. Using the second order system model, the PDF controller offers arbitrary pole placement. In this paper, the stability proof for the controller with stick-slip friction is presented. On the basis of this proof, the stability criteria are derived. The paper also includes both the computer simulation and the experimental works to confirm the theoretical result. The experiments conducted on a Traction Type Drive Device (TTDD) shows that control accuracy of as high as ±1 arc – second is achieved.

Nonlinear Modeling of Human Quiet Standing

2012 ◽  
Vol 523-524 ◽  
pp. 717-721
Author(s):  
Hiroyuki Takagi ◽  
Takuya Tabata ◽  
Ken Sasaki
Keyword(s):  
Nonlinear Control ◽  
Ankle Joint ◽  
Center Of Pressure ◽  
Control Model ◽  
Joint Torque ◽  
Quiet Standing ◽  
Upper Body ◽  
Joint Control ◽  
Maximum Deviation ◽  
Evaluation Indexes

Fluctuation during quiet standing of a person is one of the evaluation indexes of aging. Usually, fluctuation is measured by the center of the subject’s weight distribution on the floor, which is called center-of-pressure (COP), or the two dimensional trajectory of the top of the head taken from above the subject. In both cases, common evaluation indexes are standard deviation or maximum deviation. Control models of human quiet standing have been proposed and studied, and now it is widely accepted that human quiet standing is a nonlinear control system. However, there is no established nonlinear control model that expresses the characteristics of human quiet standing accurately. If we could express the nonlinear control dynamics of human quiet standing, the parameters of the control model can be utilized to evaluate subject’s motor control ability in more detail. In this study, we modeled the human body as a two link inverted pendulum. Leaning angle of the lower body and the upper body, and COP were measured in the experiment. Analysis of the data has revealed an asymmetry in the ankle joint torque in the anterior-posterior postural control. This asymmetry was modeled by asymmetric feedback gains of the feedback loop of ankle joint control. The proposed nonlinear model was verified by comparing the simulation results and the experimental data.

IDENTIFICATION OF DYNAMIC PATTERNS OF BODY SWAY DURING QUIET STANDING: IS IT A NONLINEAR PROCESS?

2010 ◽  
Vol 20 (04) ◽  
pp. 1269-1278 ◽  
Author(s):  
HAMED GHOMASHCHI ◽  
ALI ESTEKI ◽  
JULIEN CLINTON SPROTT ◽  
ALI MOTIE NASRABADI
Keyword(s):  
Time Series ◽  
Postural Control ◽  
Correlation Dimension ◽  
Postural Sway ◽  
Convincing Evidence ◽  
Temporal Organization ◽  
Quiet Standing ◽  
Body Sway ◽  
Linear Measure ◽  
Control Mechanisms

During quiet standing, the human body continuously moves about an upright posture in an erratic fashion. Many researchers characterize postural fluctuations as a stochastic process while some others suggest chaotic dynamics for postural sway. In this study, first we examined these assumptions using principles of chaos theory in normal healthy and in patients with deteriorated postural control mechanisms. Next, we compared the ability of a nonlinear dynamics quantifier correlation dimension to that of a linear measure standard deviation to describe variability of healthy and deteriorated postural control mechanisms during quiet standing. Our findings did not provide convincing evidence for existence of low dimensional chaos within normal and abnormal sway dynamics but support the notion that postural fluctuations time series are distinguishable from these generated by a random process. The results indicated that although linear variability measures discriminated well between groups, they did not provide any information about the structure of postural fluctuations. Calculated correlation dimension as a complexity measure which describes spatio temporal organization of time series may be useful in this regard.

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