IEEE Robotics and Automation Magazine curated by the IEEE Robotics and Automation Society have published an extensive 12-page article on the WalkON Suit. The WalkON Suit is a powered exoskeleton that successfully enables a completely paralyzed from the waist down user (pilot) to walk, sit, move with targeted foot placement, climb and descend stairs. The WalkON Suit was constructed by SG Robotics in association with Sogang University and supported by grants from the government of Korea.
The WalkON Suit competed in the 2016 Cybathlon Powered Exoskeleton Race in the Swiss Arena in Kloten near Zürich. The Cybathlon was different from other wearable robotic events due to its emphasis on everyday tasks that disabled people have to face daily. For the powered exoskeleton race, this included:
- Sitting on a couch. This was more difficult than it sounds, as the couches chosen in the competition were low to the ground and quite soft, exceeding the degrees of freedom for some of the exoskeletons and their users.
- Navigating a zig-zag course. A challenge for most exoskeletons that provide motorized motion in just a single plane. Changing direction is usually done manually with crutches.
- Stepping on “stones.” A particularly difficult challenge because the last step was positioned much further than the rest, presenting a challenge between control and stride length.
- Navigating a sideways sloped surface. In addition to most devices focusing in only one plane of motion, the IEEE article emphasizes that adjusting for the sideways inclination is made even more difficult by the raised center of gravity of the paralyzed user due to his loss of mass in the lower body.
- Climbing a ramp, ascending and descending stairs.
- Opening and closing a door.
- Navigating without support operators. The users (pilots) had to control the wearable machines by themselves.
The WalkON Suit team was able to physically complete all of the above challenges with the exception of the sideways incline. (You can read more from our coverage on the Cybathlon here.)
The IEEE article on the WalkON Suit can be accessed through the IEEE Robotics & Automation Magazine site: http://www.ieee-ras.org/publications/ram. Highlights include the use of four smaller electrical motors for each joint. It will be curious to see if this develops into a trend?
Another interesting engineering choice by the SG team was to use a leg orthosis that attaches to the user, which in turn attaches to the exoskeleton. The idea of having a mandatory, specifically designed or modified clothing or brace between the user and the wearable robot is not new, but in practice, it is rarely utilized. One of the main issues with using powered exoskeletons is the creation of pressure points and skin damage due to imperfect fit or components sliding across the body creating shear forces. One strategy is to have highly customizable exoskeletons that can fit perfectly on the user. Another strategy, as the one used here and by companies like Myomo for their arm exoskeleton is to create a custom brace for each user and then fit the exoskeleton components to the brace. A third strategy is to forgo the exoskeleton frame altogether and reduce the wearable robot to an exosuit, made exclusively out of soft materials.
The WalkON team also reports that user experience and comfort with the powered exoskeleton is critical to the walking speed and energy consumption. This is identical to ReWalk’s commercial materials that emphasize that a ReWalk user with one month of experience with their exoskeleton, a user with one year of experience and a user with five or more years will demonstrate significantly different capabilities. This also highlights the danger of choosing or evaluation a rehabilitation exoskeleton based on just wearing it once or twice.
More than a year after the Cybathlon, the competition continues to inspire engineers, researchers, and clinicians to share their experiences. The Cybathlon was successful in putting the spotlight on the challenges of everyday tasks for people with complete lower body paralysis.
IEEE Robotics & Automation Magazine, http://www.ieee-ras.org/publications/ram, accessed Jan 2018
WalkON Suit: A Medalist in the Powered Exoskeleton Race of Cybathlon 2016, IEEE Robotics & Automation Magazine, November 2016, http://ieeexplore.ieee.org/document/8097012/
SG Robotics, Robotics for a Better Life, http://sg-robotics.com/walkon?ckattempt=1
CYBATHLON 2016 & 2020, http://www.cybathlon.ethz.ch