'Section 2 - Design and control of exoskeletons' (Control, Robotics and Sensors, 2018), 'Wearable Exoskeleton Systems: Design, control and applications', Chap. sec2, pp. 97-98, DOI: 10.1049/PBCE108E_sec2
IET Digital Library, https://digital-library.theiet.org/;jsessionid=1kiv8yeb249a4.x-iet-live-01content/books/10.1049/pbce108e_sec2