1. Department of Electronics, Information and Bioengineering, Politecnico di Milano, 20133 Milan, Italy
2. Orthopaedic Rehabilitation Unit and Research Laboratory in Biomechanics, Rehabilitation and Ergonomics, San Giuseppe Hospital, IRCCS Istituto Auxologico Italiano, 28824 Piancavallo, Italy
3. Department of Surgical Sciences, Physical Medicine and Rehabilitation, University of Turin, 10126 Turin, Italy
4. Clinica Hildebrand, Centro di Riabilitazione Brissago, CH-6614 Brissago, Switzerland