@conference {1987, title = {Soft-Actuators in Cyclic Motion: Analytical Optimization of Stiffness and Pre-Load}, booktitle = {IEEE-RAS International Conference on Humanoid Robots}, year = {2013}, address = {Atlanta, Georgia, USA}, keywords = {Robotics}, author = {A. Velasco and G M Gasparri and M. Garabini and L. Malagia and P Salaris and A. Bicchi} }