Validation of a modular and wearable system for tracking fingers movements

Supervising manual operations performed by workers in industrial environments is crucial in a smart factory. Indeed, the production of products with superior quality at higher throughput rates and reduced costs with the support of Industry 4.0-enabling technologies is based on the strict control of all resources inside the factory, including workers. This paper shows a protocol for validating a new wearable system for tracking finger movements. The wearable system consists of two measuring modules worn on the thumb and index finger that measure flexion and extension of the proximal interphalangeal (PIP) joint by a stretch sensor and rotation of the proximal phalanx (PP) by an inertial measurement unit. A marker-based opto-electronic system is used to validate the proposed device by capturing specific finger movements. Four movements that simulate typical tasks and gestures, such as grasp and pinch, were specifically performed. The maximum root-mean-square error is 3.7 deg for the roll angle of PP. The resistance changes of the stretch sensors with respect to flexion and extension of the PIP joint is 0.47 Ω/deg. The results are useful for data interpretation when the system is adopted to monitor finger movements and gestures.