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According to the National Spinal Cord Injury Statistical Center, somewhere between 236,000 to 327,000 people in the US are living with serious spinal cord injuries. About 155,000 have paraplegia. Until now, being able to stand and walk again has been only been a dream for people paralyzed below the waist.

Fig. 1 - Brian Shaffer standing in the Parker exoskeleton. (Courtesy of Joe Howell, Vanderbilt University)
But that dream is something that may someday come to be realized, say engineers at the Vanderbilt University Center for Intelligent Mechatronics (CIM), Nashville, TN. They have developed a powered exoskeleton that can enable those with severe spinal cord injuries to not only stand, but walk, sit, and climb stairs. The robotic suit is light in weight, compact in size, and modular in design.

Over the past decade, advances in robotics, microelectronics, battery, and electric motor technologies have advanced to where developing exoskeletons to aid people with disabilities has become practical.

These devices act like an external skeleton. They are strapped in tightly around the torso and rigid supports are strapped to the person’s legs and extend from the hip to the knee and from the knee to the foot. The joints for the hips and knees are driven by computer-controlled electric motors powered by advanced batteries. Patients can use the powered apparatus with walkers or forearm crutches to help to maintain their balance.

“You can think of our exoskeleton as a Segway with legs,” said Michael Goldfarb, the H. Fort Flowers Chair in Mechanical Engineering and professor of physical medicine and rehabilitation. “If the person wearing it leans forward, he moves forward. If he leans back and holds that position for a few seconds, he sits down. When he is sitting down, if he leans forward and holds that position for a few seconds, then he stands up.”

Brian Shaffer, who was completely paralyzed from the waist down in an automobile accident on Christmas night 2010, has been testing the Vanderbilt apparatus at the Nashville-area satellite facility of the Shepherd Center, based in Atlanta, one of the top rehabilitation hospitals for spinal cord and brain injury rehabilitation in the nation. “My kids have started calling me ‘Ironman,’” he said. (See Figure 1)

“It’s unbelievable to stand up again. It takes concentration to use it at first but, once you catch on, it’s not that hard: The device does all the work. I don’t expect that it will completely replace the wheelchair, but there are some situations, like walking your daughter down the aisle at her wedding or sitting in the bleachers watching your son play football, where it will be priceless,” he explained.

Physical therapists working with patients at the Shepherd Center have provided Vanderbilt engineers with clinical feedback needed to develop and advance the device. Getting patients upright and moving again provides major health benefits in addition to the psychological ones. People who rely on a wheelchair to move around can develop serious urinary, respiratory, cardiovascular, and digestive problems, as well as getting osteoporosis, pressure sores, blood clots and other afflictions associated with lack of mobility.

The Vanderbilt design has a modular design that can provide its users with an unprecedented degree of independence. Users will be able to transport the compact device on the back of their wheelchair. When they reach a location where they want to walk, they will be able to put on the exoskeleton by themselves without getting out of the wheelchair. When they are done walking, they can sit back down in the same chair and take the device off or keep it on and propel the wheelchair to their next destination. In addition, it weighs only about 27 pounds, and since it is compact, its wearers can fit into a standard- sized wheelchair. The university has several patents pending on the design. (See Figure 2)

Some potential advantages, include:

Fig. 1 - Brian Shaffer standing in the Parker exoskeleton. (Courtesy of Joe Howell, Vanderbilt University)
The amount of robotic assistance adjusts automatically for users who have some muscle control in their legs. This allows them to use their own muscles while walking. When a user is totally paralyzed, the device does all the work. The other designs provide all the power all of the time.

It is the only wearable robot that incorporates a proven rehabilitation technology called functional electrical stimulation (FES) that applies small electrical pulses to paralyzed muscles, causing them to contract and relax. FES can improve strength in the legs of people with incomplete paraplegia. For complete paraplegics, FES can improve circulation, change bone density and reduce muscle atrophy.

Where It Stands

Parker Hannifin Corporation, Cleveland, OH, a global leader in motion and control technologies, announced on October 30 that it signed an exclusive licensing agreement with Vanderbilt University for the exoskeleton technology. The agreement gives Parker exclusive rights to develop, manufacture, and sell the device. Parker intends to invest in further development of the technology and establish a business unit targeting commercial launch of the exoskeleton device in 2014.

Two other companies — Argo Medical Technologies Ltd. in Israel and Ekso Bionics, Berkeley, CA — have already developed products of this type and are marketing them in the US. Argo, in fact, expanded to announce its new US headquarters in Marlborough, MA, in October.

The Argo ReWalk™ exoskeleton suit enables persons with lower limb disabilities to stand and walk independently without assistance. Its founder, Dr. Amit Goffer, has quadriplegia and was inspired to invent the exoskeleton device because of his own condition. The ReWalk is available in the US at rehabilitation centers and is awaiting FDA clearance for personal use. In Europe, it is also being used in rehabilitation facilities, and ARGO recently announced its commercial availability for personal use throughout the European Union.

The Ekso™ is a bionic, wearable robot for people with lower-body paralysis. Using a combination of motors and sensors, it allows the user to walk over ground with a human-like gait. It’s ready to wear, battery-powered, and can be strapped on in less than 5 minutes. Originally Berkeley Bionics, Ekso Bionics was founded in Berkeley, California in 2005. Since its inception, Ekso Bionics has forged partnerships with world-class institutions like UC Berkeley, received research grants from the Department of Defense, and licensed technology to the Lockheed Martin Corporation.

CIM Future Work

Vanderbilt’s Center for Intelligent Mechatronics focuses on the design and control of electromechanical devices, with a particular emphasis on the emerging field of rehabilitation robotics. In addition to the powered exoskeleton, its current projects include a powered, multidegree- of-freedom prosthetic arm, and a powered transfemoral prosthesis that enhances mobility and reduces falls for lower-limb amputees.