External finger forces in submaximal five-finger static pinch prehension

Abstract

Small conductive polymer force sensors were attached to the distal phalangeal pads for measuring individual finger forces exerted during submaximal static pinch. A linear force summing strain gauge dynamometer for measuring resultant five-finger pinch force was grasped vertically using a neutral wrist posture. Individual finger forces were measured at fixed total pinch force levels of 10%, 20%, and 30% of maximum voluntary exertion using pinch spans of 45 mm and 65 mm. Total pinch force and individual finger forces were also measured while similarly grasping the dynamometer and supporting fixed weights for 1.0 kg, 1.5 kg, and 2.0 kg loads using pinch spans of 45 mm and 65 mm. The index and middle fingers exerted more than 3 N greater average force than the ring and small fingers for the fixed total pinch force task. No significant individual finger force differences were observed at the 10% maximum voluntary exertion level, however both the index and middle fingers exerted more than 5 N greater force than the ring and small fingers at the 30% maximum voluntary exertion level. The average contribution of the index, middle, ring, and small fingers were 33%, 33%, 17%, and 15%, respectfully, for the fixed total pinch force task. As exertion level increased from 10% to 30%, the contribution of the middle finger was not constant increasing from 25% to 38%. Total pinch force increased from 15 N to 30 N when the load weight increased from 1.0 kg to 2.0 kg.(ABSTRACT TRUNCATED AT 250 WORDS)

Prehension synergies during nonvertical grasping, I: experimental observations

“…Many examples of this exist in the literature (e.g., Kinoshita et al 1995;Latash et al 1998a,b;Li et al 1998;Radwin et al 1992). Tangential force-sharing stability when load is changed is also not new .…”

Fibre optic-based force sensor for bio-mimetic robotic finger

“…It is apparent from the simulation that the maximum applied force (i.e. 5[N], mean maximum external finger force [6]) on the cantilever is significantly lower than the yield strength of the material selected for manufacturing the real finger ( i.e. ABS plastic) [7].…”

Evaluation of the Contributions of Individual Finger Forces in Various Submaximal Grip Force Exertion Levels

“…However, the study of Radwin et al (1992) observed only three levels of grip forces at slightly low levels of less than 30% MVC, and therefore there is a difficulty to compare with contributions upon exerting bigger forces.…”

“…A study on each finger's contribution is important to establish hand's biomechanical models, and design and improve hand tools and manual activities (Radwin et al, 1992). Especially, the acquisition of each finger's contribution and biomechanical data in the ergonomics field is not only essential information in the design of hand tools or prosthetic hand (Crago et al, 1991), robotic arm (Mason and Salisbury, 1985), and working environment, but can be used as vital information in the judgment of hand function's abnormality .…”

“…According to researches on the contribution of individual finger force) upon submaximal voluntary contraction (10, 20, 30% MVCs) of Radwin et al (1992), middle finger's contribution increased from 25% to 38%, when force increased from 10% MVC to 30% MVC, whereas index finger's MVC decreased from 35% to 31%. However, the study of Radwin et al (1992) observed only three levels of grip forces at slightly low levels of less than 30% MVC, and therefore there is a difficulty to compare with contributions upon exerting bigger forces.…”