@article {3641, title = {A Spherical Active Joint for Humanoids and Humans}, journal = {IEEE Robotics and Automation Letters}, volume = {Volume: 4 , Issue: 2 , April 2019}, year = {2019}, month = {01/2019}, author = {S. Mghames and M. G. Catalano and A. Bicchi and G. Grioli} }