1. Bioengineering Department, Imperial College London, London, U.K
2. Department of Electrical Engineering, Chalmers University of Technology, Gothenburg, Sweden
3. Faculty of Electrical Engineering and Computer Science, University of Maribor, Slovenia
4. Department of Mechanical Engineering and Neuroscience Center, Brigham Young University, Provo, UT, USA
5. Legs and Walking Ability Laboratory, Shirley Ryan AbilityLab, Chicago, IL, USA