1. Department of Mechanical and Aerospace Engineering, University of California Irvine, Irvine, CA, USA
2. Rehabilitation Services, University of California Irvine Medical Center, Orange, CA, USA
3. Flint Rehabilitation Devices, Irvine, CA, USA
4. Department of Anatomy and Neurobiology, the Department of Mechanical and Aerospace Engineering, and the Department of Biomedical Engineering, University of California Irvine, Irvine, CA, USA