Comparison of control strategies for an EMG controlled orthotic exoskeleton for the hand

To restore dexterity to paralyzed hands, we have designed and constructed a lightweight, low-profile orthotic exoskeleton controlled by the user´s residual electromyography (EMG) signals. In this paper, we compared several simple strategies to control the orthotic device for a quadriplegic (C5/C6) subject. When contralateral arm control was employed, we found that a simple on/off strategy allowed for faster interaction with objects, while variable control provided more controlled interactions, especially with deformable objects. Furthermore, we designed a control strategy that allowed for a natural reaching and pinching sequence without the use of the contralateral arm. We validated that the EMG signal from the ipsilateral biceps could be used to develop an extremely reliable natural reaching and pinching algorithm. This evaluation showed that different control strategies may be appropriate for different situations, and further investigation on the natural algorithm is crucial.