Design of wearable robotic extra fingers for human hand augmentation

Augmenting the human body with supernumerary robotic extra limbs is a cutting-edge research topic with many potential applications. In this paper we focus on human hand augmentation with robotic extra fingers, used in particular as compensatory and rehabilitation tool for people with upper limb impairments. We designed and developed devices composed of single or multiple extra fingers. Underactuation and compliance are design choices that can reduce the device complexity and weight, maintaining the adaptability to different grasped objects. Each finger is composed of modular phalanges and is actuated with a single tendon. Interphalangeal joints include a passive elastic element that allows restoring the initial reference configuration when the tendon is released. The stiffness of each passive element can be customized in the manufacturing process and can be chosen according to a desired closure movement of the fingers. This paper summarizes the main design principles and the main applications that have been exploited.https://youtu.be/plMpW1A50j