Collaborative robots are getting smarter all the time. They are being improved to operate more safely around humans. Domenico Prattichizzo and his colleagues have come up with an interesting approach to allow robots to communicate with humans. The approach involves using a vibrating ring that sends acknowledgements to the user from the robot.
The ring vibrates as soon as the robot understands the user’s intention. Andrea Casalino, Costanza Messeri, Maria Pozzi, Andrea Maria Zanchettin, Paolo Rocco, and Domenico Prattichizzo are behind this idea. More info is available here.