Track: Human Factors and Ergonomics

Abstract

Manual wheelchair users face many difficulties during their daily activities. These users demand a high amount of force from their upper extremities to move or turn. Due to exerting these forces over time, more pressure on the wrist’s median nerve is applied, and the users suffer from severe pain in their arm muscles.  In general, manual wheelchair users provide repetitive motion for an extended time leading to CTS. This study uses digital human modeling to investigate wrist deviation in radial and extension positions, body dimension, and gender on the maximum hand force. Three wrist radial deviation (i.e., 10°, 15°, and 20°), three extension wrist degrees (i.e., 25°, 35°, and 50°), both genders (i.e., male and female), and three percentiles (i.e., 5th, 50th, 95th) are involved.  Jack digital human modeling software was used to simulate the wrist's deviation and test different body sizes. Force solver in Jack software calculates the amount of maximum hand force for 54 combination runs. Analysis of variance was used to determine the significant factors. The results show that radial deviation has no significant impact on the maximum hand force, while other factors have a considerable impact. The male, in general, provides more strength than the female. A person with the 95th percentile has less force than 50th, and both are less than 5th (62, 68, and 74, respectively). Wrist extension on 25° provides 95 Neuton force which is the maximum between another extension angel.