Evaluation of Containment Force Variability between Different Grades of Stretch Film

The purpose of the current investigation was to examine the influence of intermittency in visual information processes on intermittency in the control continuous force production. Adult human participants were required to maintain force at, and minimize variability around, a force target over an extended duration (15 s), while the intermittency of on-line visual feedback presentation was varied across conditions. This was accomplished by varying the frequency of successive force-feedback deliveries presented on a video display. As a function of a 128-fold increase in feedback frequency (0.2 to 25.6 Hz), performance quality improved according to hyperbolic functions (e.g., force variability decayed), reaching asymptotic values near the 6.4-Hz feedback frequency level. Thus, the briefest interval over which visual information could be integrated and used to correct errors in motor output was approximately 150 ms. The observed reductions in force variability were correlated with parallel declines in spectral power at about 1 Hz in the frequency profile of force output. In contrast, power at higher frequencies in the force output spectrum were uncorrelated with increases in feedback frequency. Thus, there was a considerable lag between the generation of motor output corrections (1 Hz) and the processing of visual feedback information (6.4 Hz). To reconcile these differences in visual and motor processing times, we proposed a model where error information is accumulated by visual information processes at a maximum frequency of 6.4 per second, and the motor system generates a correction on the basis of the accumulated information at the end of each 1-s interval.

Download Full-text

Motor-Unit Pool Model of Continuous and Discrete Force Variability

Motor Control ◽

10.1123/mcj.15.4.439 ◽

2011 ◽

Vol 15 (4) ◽

pp. 439-455 ◽

Cited By ~ 1

Author(s):

Xiaogang Hu ◽

Karl M. Newell

Keyword(s):

Motor Unit ◽

Force Variability ◽

Pool Model

Download Full-text

Intermittent Visuomotor Processing in the Human Cerebellum, Parietal Cortex, and Premotor Cortex

Journal of Neurophysiology ◽

10.1152/jn.00718.2005 ◽

2006 ◽

Vol 95 (2) ◽

pp. 922-931 ◽

Cited By ~ 65

Author(s):

David E. Vaillancourt ◽

Mary A. Mayka ◽

Daniel M. Corcos

Keyword(s):

Parietal Cortex ◽

Visual Feedback ◽

Visual Information ◽

Grip Force ◽

Premotor Cortex ◽

Force Variability ◽

Neural Activation ◽

Control Force ◽

Force Condition ◽

Visuomotor Processing

The cerebellum, parietal cortex, and premotor cortex are integral to visuomotor processing. The parameters of visual information that modulate their role in visuomotor control are less clear. From motor psychophysics, the relation between the frequency of visual feedback and force variability has been identified as nonlinear. Thus we hypothesized that visual feedback frequency will differentially modulate the neural activation in the cerebellum, parietal cortex, and premotor cortex related to visuomotor processing. We used functional magnetic resonance imaging at 3 Tesla to examine visually guided grip force control under frequent and infrequent visual feedback conditions. Control conditions with intermittent visual feedback alone and a control force condition without visual feedback were examined. As expected, force variability was reduced in the frequent compared with the infrequent condition. Three novel findings were identified. First, infrequent (0.4 Hz) visual feedback did not result in visuomotor activation in lateral cerebellum (lobule VI/Crus I), whereas frequent (25 Hz) intermittent visual feedback did. This is in contrast to the anterior intermediate cerebellum (lobule V/VI), which was consistently active across all force conditions compared with rest. Second, confirming previous observations, the parietal and premotor cortices were active during grip force with frequent visual feedback. The novel finding was that the parietal and premotor cortex were also active during grip force with infrequent visual feedback. Third, right inferior parietal lobule, dorsal premotor cortex, and ventral premotor cortex had greater activation in the frequent compared with the infrequent grip force condition. These findings demonstrate that the frequency of visual information reduces motor error and differentially modulates the neural activation related to visuomotor processing in the cerebellum, parietal cortex, and premotor cortex.

Download Full-text

Force Control Strategy of Five-Digit Precision Grasping With Aligned and Unaligned Configurations

Human Factors The Journal of the Human Factors and Ergonomics Society ◽

10.1177/00187208211040914 ◽

2022 ◽

pp. 001872082110409

Author(s):

Po-Tsun Chen ◽

Hsiu-Yun Hsu ◽

You-Hua Su ◽

Chien-Ju Lin ◽

Hsiao-Feng Chieh ◽

...

Keyword(s):

Control Strategy ◽

Force Control ◽

Task Type ◽

Applied Force ◽

Force Variability ◽

Force Transducers ◽

Task Requirements ◽

Power Grasp ◽

Precision Grasping ◽

Large Moment

Objective To investigate the digit force control during a five-digit precision grasp in aligned (AG) and unaligned grasping (UG) configurations. Background The effects of various cylindrical handles for tools on power grasp performance have been previously investigated. However, there is little information on force control strategy of precision grasp to fit various grasping configurations. Method Twenty healthy young adults were recruited to perform a lift-hold-lower task. The AG and UG configurations on a cylindrical simulator with force transducers were adjusted for each individual. The applied force and moment, the force variability during holding, and force correlations between thumb and each finger were measured. Result No differences in applied force, force correlation, repeatability, and variability were found between configurations. However, the moments applied in UG were significantly larger than those in AG. Conclusion The force control during precision grasp did not change significantly across AG and UG except for the digit moment. The simulator is controlled efficiently with large moment during UG, which is thus the optimal configuration for precision grasping with a cylindrical handle. Further research should consider the effects of task type and handle design on force control, especially for individuals with hand disorders. Application To design the handle of specific tool, one should consider the appropriate configuration according to the task requirements of precision grasping to reduce the risk of accumulating extra loads on digits with a cylindrical handle.

Download Full-text

Effects of aging on motor control strategies during bimanual isometric force control

Adaptive Behavior ◽

10.1177/1059712319849896 ◽

2019 ◽

Vol 27 (4) ◽

pp. 267-275

Author(s):

Yan Jin ◽

JiWon Seong ◽

YoungChae Cho ◽

BumChul Yoon

Keyword(s):

Older Adults ◽

Motor Control ◽

Control Strategy ◽

Force Control ◽

Isometric Force ◽

Control Strategies ◽

Force Variability ◽

Dual Tasking ◽

Effects Of Aging ◽

Force Accuracy

Aging-induced degeneration of the neuromuscular system would result in deteriorated complex muscle force coordination and difficulty in executing daily activities that require both hands. The aim of this study was to provide a basic description of how aging and dual-task activity would affect the motor control strategy during bimanual isometric force control in healthy adults. In total, 17 young adults (aged 25.1 ± 2.4 years) and 14 older adults (aged 72.6 ± 3.4 years) participated in the study. The subjects were instructed to press both hands simultaneously to match the 1 Hz sine curve force under two conditions (with or without calculation) with continuous visual feedback. Differences in bimanual motor synergy, bimanual coordination, force accuracy, force variability, and calculation speed were compared. This study found that the specific motor control strategy of older adults involved a decreased bimanual force control ability with both increased VUCM and VORT, and was not influenced by dual tasking. These findings might have implications for establishing interventions for aging-induced hand force control deficits.

Download Full-text

Force Variability as an Objective Measure of Surgical Skill

Jurnal Teknologi ◽

10.11113/jt.v74.4677 ◽

2015 ◽

Vol 74 (6) ◽

Author(s):

Siti Nor Zawani Ahmmad ◽

Chew Zhen San ◽

Eileen Su Lee Ming ◽

Yeong Che Fai

Keyword(s):

Objective Measure ◽

Assessment Model ◽

Force Variability ◽

Surgical Skill ◽

Control Task ◽

Force Matching ◽

Significant Difference ◽

Target Force ◽

The Mean ◽

Different Levels

This study investigated the force variability of subjects with different level of surgical skills for different force levels. Twelve participants were recruited from three different levels of surgical experiences: A group of surgeon (N = 4), medical student (N = 3) and engineering student (N = 5) underwent a simple finger force control task using a custom developed ‘Force Matching’ module. Three different levels of target force were used: 2 N, 4 N, and 6 N. The task was performed simultaneously using right and left hands. The mean error of force was measured to compare the performance between the three group using Kruskal-Wallis test. A statistically significant difference was detected among the three groups at 2 N when using right hand. We also found that the surgeon group made less error compared to the two other groups at force level 4 N and 6 N for both hands. This finding has important implication for developing a parametric assessment model to evaluate basic skill level in surgical procedures. However, for most accurate result, a big sample size of subject is required.

Download Full-text