M. G.  Catalano, Grioli, G., Garabini, M., Bonomo, F., Mancini, M., Tsagarakis, N. G., and Bicchi, A., ?VSA - CubeBot. A modular variable stiffness platform for multi degrees of freedom systems?, in 2011 IEEE International Conference on Robotics and Automation, Shangai, China, 2011, pp. 5090 - 5095.