Control interfaces to actively support the arm function of men with Duchenn Muscular Dystrophy

Abstract

Adults with DMD can benefit from active arm supports that augment their residual functional capabilities. However, intuitively controlled and fully actuated arm supports are currently not commercially available and adults with DMD are limited to use external robotic arms which contribute to the disuse of their arms. To fill this gap in the field of arm supports, we have developed EMGand force-based control interfaces that have been implemented in two new active arm supports: the A-Arm and the Active A-Gear.We found that both EMGand force-based control interfaces are feasible solutions for the control of active arm support for adults with DMD that have lost their arm function a long time ago. The comparative studies between EMG and force-based control interfaces indicated that, in general, EMG-based control interfaces are better suited for adults with DMD than force-based control interfaces as they are experienced as less fatiguing. Nevertheless, force-based control interfaces with active gravity and joint-stiffness compensation can be a better alternative for those cases in which voluntary forces would still be higher than the intrinsic forces of the arms. This conclusion has an indicative value, as it is based on a low number of subjects. In any case, the decision on the most suited interface will have to be taken based on the specificities of each subject. In conclusion, by developing these new control interfaces and implementing them in new active assistive devices, we made a significant step in improving arm supports for adults with DMD. Hopefully, these novel concepts of arm supports will be the basis for the development of commercially available active arm supports for people with severe muscular weakness. The control and assistive strategies developed in the Flextension A-Gear project may be applicable to other patient groups with muscular weakness.