Shaoping Bai, ; Christensen, Simon; Islam, Muhammad Raza: 'Design and control of spherical shoulder exoskeletons for assistive applications' (Control, Robotics and Sensors, 2018), 'Wearable Exoskeleton Systems: Design, control and applications', Chap. 5, pp. 99-118, DOI: 10.1049/PBCE108E_ch5
IET Digital Library, https://digital-library.theiet.org/;jsessionid=3iwl61qlpk2rk.x-iet-live-01content/books/10.1049/pbce108e_ch5