M.  Bagheri, A. Ajoudani, Lee, J., Caldwell, D. G., and Tsagarakis, N. G., ?Kinematic Analysis and Design Considerations for Optimal Base Frame Arrangement of Humanoid Shoulders?, in IEEE International Conference on Robotics and Automation (ICRA2015), Seattle, USA, 25 - 30 May, 2015, pp. 2710 - 2715.