iStride™ Device

A Split-belt treadmill as part of the USF CAREN system.

Walking requires precise coordination between the legs. This interlimb coordination is often impaired in individuals with central nervous system lesion, such as stroke, resulting in an asymmetric walking pattern and a slower walking velocity. Walking on a split-belt treadmill, which has two belts moving the legs at different speeds, has been shown to correct walking asymmetries in people with stroke. One distinct drawback is that learning on the treadmill does not transfer completely to walking over the ground. Although regular and more frequent training leads to greater rehabilitation, another drawback of a split-belt is that people cannot practice in their more natural everyday environment, such as at home. Walking on a treadmill is a stationary task, so the sensory information experienced while walking over ground, such as the optic/visual flow of motion, is not the same as that while walking on a treadmill. It has been hypothesized that the limited transfer to over-ground walking is due to the conflicting sensory experiences between the treadmill training environment and the over-ground environment. The perceptual change gives the individual cues that the new environment is not the same as that in which he was trained. Mimicking the effects of the split-belt treadmill while walking over ground can alleviate the dynamic and psychological differences of walking on a treadmill and, thus, increase the transfer of the new walking pattern from treadmill to over-ground walking.

Our innovative iStride™ Device can impose a motion to a foot that is capable of changing interlimb coordination and the resulting walking velocity while walking over ground. The iStride™ Device creates a motion similar to that felt when walking on a split-belt treadmill, but while walking over ground where the sensory information of the real world task will be experienced. The objective of this proposed research and development is to validate the use of the iStride™ Device for long-term correction of the wearer's gait. The iStride™ Device design uses no external power since the shoe mechanically converts the wearer's downward and horizontal forces into a horizontal motion. This shoe design is completely mobile, which opens up the doors to enabling long-term continuous rehabilitation outside the rehabilitation clinic. We anticipate that both the longer use of the device and experiencing gait modifications in real world environments will aid in achieving better rehabilitation outcomes.

Several prototypes have been developed and tested. The first version was passive and completely mechanical, but it had no control of the backward foot motion. Although it moved the wearer's foot backward, it did so in a jerky and fairly unpredictable motion comparable to sliding on ice or a slippery surface. The second version provided a smooth motion by controlling the generated horizontal motion. However, because of the various motion controls, this version ended up being too high off the ground and too heavy for actual subject testing. The third and fourth prototypes built upon the third being purely passive and completely mechanical, while introducing a rotary damper to regulate the backward motion of the foot. The fifth (not shown here) is currently undergoing a clinical trial.

While the invention of the iStride™ Device started at the REED Lab at the University of South Florida, commercialization is moving forward in collaboration with Moterum Technologies.

Asymmetric Passive Dynamic Walker

The iStride™ Device design is advancing. While there have been several prototypes, the design and manufacture of the iStride™ Device is an ongoing process toward finding an optimum design that realistically can be comfortably and safely implemented by gait asymmetry patients for rehabilitation.

A Passive Dynamic Walker (PDW) Model has also implemented to help in the analysis and optimization of the iStride™ Device. A PDW is a passive mechanical device that walks in a human-like manner down an incline by using only the force of gravity. Such virtual modeling is very useful and a crucial step in the design process of a physical iStride™ Device prototype and the prediction of the body dynamics of a person using a iStride™ Device.

• L. Rashford, B. Darcy, E. Lundin, R. Medas, T. Shultz, E. DuBose, D. Huizenga, K. B. Reed. "Active Limb Orthosis for Home Use - Stroke Gait Rehabilitation", American Congress of Rehabilitation Medicine (ACRM), November 2019.
• S. Kim, D. Huizenga, I. Handzic, R. Ditwiler, M. Lazinski, T. Ramakrishnan, A. Bozeman, D. Rose, K. B. Reed. "Relearning functional and symmetric walking after stroke using a wearable device: a feasibility study," Journal of NeuroEngineering and Rehabilitation, Volume 16, 2019.
  [ Springer Nature ]
• S. H. Kim, D. Huizenga, I. Handzic, R. Edgeworth, M. Lazinski, T. Ramakrishnan, D. Rose, K. B. Reed. "Device for Improving Double Limb Support, Step Length Symmetry, and Gait Speed in Hemiparetic Patients", in Archives of Physical Medicine and Rehabilitation, v. 98, issue 10, p. e52
  [ pdf ]
• S. H. Kim, I. Handzic, D. Huizenga, R. Edgeworth, M. Lazinski, T. Ramakrishnan, and K. B. Reed. "Initial Results of the Gait Enhancing Mobile Shoe on Individuals with Stroke," in Intl. Conf. of the IEEE Engineering in Medicine and Biology Society (EMBC), Orlando, USA, 2016.
  [ pdf ]
• "Gait-Altering Shoe," K. B. Reed and I. Handzic, U.S. Patent 9,295,302, issued March 29, 2016, priority date February 17, 2012.
  [ USPTO ]
• I. Handzic and K. B. Reed. "Kinetic Shapes: Analysis, Verification, and Applications," ASME Journal of Mechanical Design, Vol. 136, No. 6, pp. 061005(1-8), 2014.
  [ ASME | pdf | abstract ]
• I. Handzic and K. B. Reed, "Comparison of the Passive Dynamics of Walking on Ground, Tied-belt and Split-belt Treadmills, and via the Gait Enhancing Mobile Shoe," Proc. of the 13th Intl. Conf. on Rehabilitation Robotics (ICORR), Seattle, USA, June, 2013.
  [ pdf ]
• I. Handzic, E. Vasudevan, and K. B. Reed, "Developing a Gait Enhancing Mobile Shoe to Alter Over-Ground Walking Coordination," Proc. of IEEE Intl. Conf. on Robotics and Automation (ICRA), St. Paul, USA, May, 2012.
  [ pdf | .mp4]
• I. Handzic, E. Barno, E. V. Vasudevan, and K. B. Reed. "Design and Pilot Study of a Gait Enhancing Mobile Shoe," Journal of Behavioral Robotics, Special Issue on Assistive Robotics, Vol. 2, Num. 4, pp. 193-201, 2011.
  [ SpringerLink | preprint | PubMed | abstract ]
• I. Handzic, E. Vasudevan, and K. B. Reed, "Motion Controlled Gait Enhancing Mobile Shoe for Rehabilitation," Proc. of the 12th Intl. Conf. on Rehabilitation Robotics (ICORR), Zurich, Switzerland, June, 2011.
  [ pdf | .mp4 | PubMed ]
• A. de Groot, R. Decker, and K. B. Reed. "Gait Enhancing Mobile Shoe for Rehabilitation," Third Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (World Haptics), Salt Lake City, USA, 2009.
  [ pdf | .mp4 ]

• "Stroke shoe retrains the brain, correcting gait"
       https://www.wndu.com/content/news/Stroke-shoe-retrains-the-brain-correcting-gait-506721291.html
• "Early study shows shoe attachment can help stroke patients improve their gait"
       https://medicalxpress.com/news/2017-12-early-patients-gait.html
• "Shoe offers stroke recovery revolution"
       http://www.fox13news.com/health/shoe-offers-stroke-recovery-revolution
• "Early study shows new shoe attachment can help stroke patients improve their gait"
       https://hscweb3.hsc.usf.edu/blog/2017/12/13/early-study-shows-new-shoe-attachment-can-help-stroke-patients-improve-gait/
• "Spirals inspire walking aids for people with disabilities"
       https://www.sciencenews.org/article/spirals-inspire-walking-aids-people-disabilities

This work has been funded by the Eunice Kennedy Shriver National Institute of Child Health & Human Development (NIH NICHD award #R21HD066200), Moterum Technologies, and the Florida High Tech Corridor.