1 Neurorehabilitation and Biomechanics Research Section, Rehabilitation Medicine Department, National Institutes of Health Clinical Center, Bethesda, MD, United States.
2 Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina-Chapel Hill, Raleigh, NC, United States.
3 Department of Bioengineering, George Mason University, Fairfax, VA, United States.
4 Center for Adaptive Systems of Brain-Body Interactions, George Mason University, Fairfax, VA, United States.
5 Department of Mechanical and Aerospace Engineering, North Carolina State University, Raleigh, NC, United States.