Kei Masani1,2, Albert H Vette3,4. 1. Rehabilitation Engineering Laboratory, Institute of Biomaterials and Biomedical Engineering, University of Toronto, 164 College Street, Toronto, Ontario, Canada, M5S 3G9. k.masani@utoronto.ca. 2. Rehabilitation Engineering Laboratory, Lyndhurst Centre, Toronto Rehabilitation Institute - University Health Network, 520 Sutherland Drive, Toronto, Ontario, Canada, M4G 3V9. k.masani@utoronto.ca. 3. Department of Mechanical Engineering, University of Alberta, 10-203 Donadeo Innovation Centre for Engineering, 9211-116 Street NW, Edmonton, Alberta, Canada, T6G 1H9. 4. Glenrose Rehabilitation Hospital, Alberta Health Services, 10230 111 Avenue NW, Edmonton, Alberta, Canada, T5G 0B7.