HandMime: Sign Language Fingerspelling Acquisition via Imitation Learning

Learning fine-grained movements is among the most challenging topics in robotics. This holds true especially for robotic hands. Robotic sign language acquisition or, more specifically, fingerspelling sign language acquisition in robots can be considered a specific instance of such challenge. In this paper, we propose an approach for learning dexterous motor imitation from videos examples, without the use of any additional information. We build an URDF model of a robotic hand with a single actuator for each joint. By leveraging pre-trained deep vision models, we extract the 3D pose of the hand from RGB videos. Then, using state-of-the-art reinforcement learning algorithms for motion imitation (namely, proximal policy optimisation), we train a policy to reproduce the movement extracted from the demonstrations. We identify the best set of hyperparameters to perform imitation based on a reference motion. Additionally, we demonstrate the ability of our approach to generalise over 6 different fingerspelled letters.