Outcomes and Perception of a Conventional and Alternative Myoelectric Control Strategy: A Study of Experienced and New Multiarticulating Hand Users.

Abstract

The development of multiarticulating hands holds the potential to restore lost function for upper-limb amputees. However, access to the full potential of commercialized devices is limited due to conventional control strategies for switching prosthesis modes, such as hand grips. For example, to switch grips in one conventional strategy, the prosthesis user must generate electromyogram (EMG) triggers (such as a cocontraction), which are cumbersome and nonintuitive. For this reason, alternative control strategies have emerged, which seek to facilitate grip switching. One specific application uses radio frequency identification (RFID) tags programmed with grip information. These tags can be placed on objects in the environment or carried on person. Upon approaching an RFID tag, the user's prosthesis reads the grip programmed on the tag and commands the hand into that grip. The purpose of this study was to compare the conventional strategy (using EMG triggers) with the alternative strategy (using RFID tags). The study evaluated three subjects: two users who actively use multiarticulating hands ("experienced" users) and one user who had never worn a multiarticulating hand ("new" user). Subjects were evaluated on two performance metrics: trigger completion time and the percentage of triggers that were successful on first attempt (first attempt success rate). Subjects also rated the difficulty, effort, and frustration with each strategy. Results suggested faster trigger completion times with the EMG strategy for the experienced users and mixed results for the new user. Overall, the three subjects rated the RFID strategy as less difficult, tiring, and frustrating than the EMG strategy. Continued studies with a larger subject pool are necessary to determine factors influencing performance and patient preference. This would allow identification of best strategies to access the full potential of new commercial devices. Still, the authors suggest that the synergistic use of both strategies can yield great benefits for both experienced and new multiarticulating hand users.