The second experiment focused on measuring the maximum forces that the device can apply to grasp objects. In this experiment, a Biopac MP36 data acquisition unit (Biopac Systems, Inc., USA) was used with the SS25LA dynamometer to measure the forces exerted during pinch and power grasps. EMG sensors were connected to the forearm of the subject to monitor the muscle activity and guarantee that the subject was not exerting any kind of involuntary forces while grasping the dynamometer. During the experiment, the forearm was placed on the table surface to keep the hand still, and the system was actuated until the torque limit of the motors was reached (3.8 N.m). Six trials were recorded and the maximum force obtained was 19.5 N for power grasps and 12.4 N for pinch grasps. The required force to grasp objects during ADLs does not exceed 15 N, and the pinch forces required to execute most of the daily life tasks are lower than 10.5 N. Thus, the proposed soft robotic glove can exert enough force to stably grasp everyday life objects.
The video below demonstrates the operation of the Hybrid, Motorized Exoskeleton Glove: