Grip Force Control Using Prosthetic and Anatomical Limbs

Abstract

ABSTRACT Introduction Skillful object manipulation in various activities of daily living requires accurate and economical modulation of grip force, yet experimental studies investigating grip force using a prosthesis are lacking. The purpose of this study was to compare grip force output between two types of upper-limb prosthetic prehensors. We hypothesized a relationship between grip force output and the muscular tension needed to control the prehensor. Materials and Methods Ten able-bodied participants attempted to produce a static target grip force using a voluntary opening and voluntary closing prosthetic simulator and their anatomical hand. The target forces were 0.49 N, 4 N, and 10.5 N. Each target force was produced three times, with and without augmented visual feedback. Performance was evaluated for error and variability. Results Using the voluntary closing device resulted in more accuracy and less variability for two of the three grip forces and followed the same trends as the anatomical hand, both of which performed inversely to the voluntary opening device. Conclusions Compared with the voluntary opening prosthesis, there may exist a more intuitive compatibility between the muscle tension used to control cable tension of a voluntary closing prosthesis and the resulting grip force of the prehensor that may benefit performance on some tasks.