Digit force coordination in constrained and natural cylindrical grasps

• Main Authors: You-HuaSu, 蘇宥華
• Other Authors: Fong-Chin Su
• Format: Others
• Language: en_US
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/88910720974643448205

碩士 === 國立成功大學 === 生物醫學工程學系 === 101 === There have been many studies investigating digits forces when holding a cylindrical object by grasping constrainedly on the same plane. However, due to the hand anatomy, the digits position was different among subjects during natural grasp. In previous studies, the pattern of digits force changed with different thumb positions. Nevertheless, there was no study to address the differences in force patterns during natural grasp and constrained grasp. Therefore, the objective of first part of this study is to compare the digits force pattern between cylindrical grasp in natural grasp (NG) and constrained grasp (CG).　 A custom cylindrical simulator with five force transducers was designed to record the applied digits forces and moments. Three markers were attached on the simulator to record the orientation of the simulator. Results of this study indicated that digits exerted larger force in constrained grasp than that in natural grasp. Besides, the contributions of finger force were majorly exerted by index and middle fingers. For these results, digits created a discrepancy force between constrained grasp and natural grasp because constrained grasp manipulated cylinder with more digits flexion which would cause digits more perpendicular to the surface of load cell and affect digits strength. According to the moments of digits, digits could be divided into three main roles. Index, middle and ring finger could be considered as a group, which compared with thumb as agonist and antagonist. Besides, little finger is stabilizer. To achieve a functional task, the proper force coordination among multi-digit and spatio-temporal control of hand motions are required. According to previous studies that patients with nerve injury will affect their digits force; however, force pattern of patients with tendon injury was unknown. Therefore, the objective of second part of this study is to compare the digits force patterns of patients with those of healthy control. Natural grasp is a proper way to collect digits forces and can be applied to patients with tendon injury to investigate their coordination ability. The results revealed that the force pattern of patients with tendon injury was differed with healthy subjects.