A Study on a Sensory Feedback Armband Providing Sensory Information of Gripping Force and Finger Posture for Patients with Hand Paralysis

Patients with hand paralysis have motor and sensory dysfunction in their hands. They can neither flex/extend their fingers nor feel gripping force or finger posture. To allow patients with hand paralysis to perform gripping motions, it is necessary to assist finger motion and provide sensory information about the gripping force and posture at the residual sensory area. We previously developed a wearable finger-motion assist system that assists finger motion and measures the gripping force necessary to present sensory information. Therefore, the purpose of this study is to propose and develop a wearable system that provides multiple types of sensory information based on gripping force and finger posture estimated by finger-motion assist system, and to confirm the basic performance of the system through experiments. We developed a band-type sensory feedback system that tightens the forearm in response to gripping force using tendon-driven wires. A vibrator is installed in it, and the intensity of vibration changes in response to finger posture. As basic experiments, identification of gripping force and finger posture using band squeezing and vibration was tested. The results showed the overall identification rate for the combination of gripping force and finger posture that were both correct was 75.6%. The identification rates for gripping force and finger posture when stimulations were presented simultaneously were 93.3 % and 80.9 %, respectively. In conclusion, we confirmed the feasibility of this system that presents multiple types of sensory information.