Exoskeletons have been a favourite in sci-fi movies for decades, from the P5000 Work Loader exoskeleton in Aliens to Iron Man’s flying, laser-blasting, rocket-firing suits. More recent movies, namely Edge of Tomorrow and Elysium, saw Tom Cruise and Matt Damon wearing combat suits that were uncannily similar to technologies being developed for the US military. Yet the armed forces are not the only ones developing real-life exoskeletons.
Professor Alberto Esquenazi, one of the world’s leading experts on exoskeletons and prosthetic limb technology, was in Singapore in March to give the plenary lecture at the Singapore Rehabilitation Conference at RehabTech Asia, where many leading medical robotics, prosthetics and exoskeleton technologies were on display. Esquenazi helped develop the ReWalk – the first commercially viable exoskeleton designed to enable people with paraplegia due to spinal cord injuries to walk. The device went on sale in the US after being approved by the Federal Drug Administration last October.
Robotic exoskeletons such as ReWalk are being developed in academic and corporate laboratories around the world, spurred on by technological advances and supported by research that shows the benefits of getting people with temporary or permanent paralysis up and walking. Doctors have long known that paralysis, or rather the lack of movement and constant sitting that results from it, can lead to a loss of bone mass, skin damage, obesity, depression and a host of other medical problems.
“ReWalk does not regenerate the spinal cord – there is no good way to do that yet,” Esquenazi said. “But when there is, there will be patients who are prepared for it, with good walking skills and good muscle strength.”
Other firms are also making steps in the field. The REX Exoskeleton, from British company Rex Bionics, made its Asian debut at RehabTech Asia. From the outset, it was designed to provide mobility to wheelchair users rather than aid the mobility of those able to walk with crutches. It allows users to stand and walk without the need for crutches, thus leaving the wearer’s hands free for other tasks.
Engineers from Vanderbilt University in Nashville, Tennessee, are also working with commercial partners Parker Hannifin to produce a robotic suit. Their suit snaps apart so that it can be carried around in a bag when not being worn.
Medical applications have, however, not been the only spur. The US military has been looking at exoskeletons for their potential to increase soldiers’ load-carrying capabilities. Researchers from the University of California created a technology that has now been licensed to defence contractor Lockheed Martin Corp to develop for the US Army. The same technology has also been developed for medical purposes by Ekso Bionics Holdings, which is using it to build bionic rehabilitation and personal mobility devices.
Another influence has come from Japanese electronics companies and carmakers that have been building and testing robots for many years. The field of prosthetics has benefitted from and contributed to technologies being developed for exoskeletons, but both have borrowed heavily from other industries. Materials such as light and super-strong titanium alloys and carbon composite elements – used to improve energy storage and return in prosthesis – come from the aerospace industry. Microprocessors that monitor and control joint movement, and accelerometers and gyroscopes that tell a suit or prosthesis precisely where it is in space, use systems similar to the anti-lock braking systems in cars, as well as other technologies similar to those in smartphones or the Wii gaming systems.
Robotic exoskeletons rely on physical components that brace a patient’s body, batteries to power the robotic components and software to both independently maintain the suit’s stability and also translate the patient commands into movements. Different models use different ways to control the suits.
Argo’s ReWalk system moves when patients lean forward. “Normally when you walk, your trunk leans forward and you step,” said Esquenazi, who is also chief medical officer for MossRehab. “By taking precisely that movement and embedding a system that detects it, you can have a person trigger the stepping pattern.” The wearer can also issue other basic commands such as stand or sit from a control device worn on the wrist.
The Indego, Vanderbilt University and Parker Hannifin exoskeleton has a controller that can be operated with one hand to leave the other free. The design team is working on adding a device that would stimulate the wearer’s limbs with electrical impulses, which might benefit muscle tone.
Meanwhile, the REX Bionics models use a joystick to initiate movement and are unique in being able to walk forward and backward as well as being able to ‘shuffle’ sideways. In April, Rex Bionics announced they had signed a distribution agreement with Deltason Medical, a distributor of rehabilitation equipment in Hong Kong and China, granting it exclusive rights to represent and distribute REX in Hong Kong, both in neuro-rehabilitation clinics and for the personal use market. They hope to make models available by the second half of 2015, making it the first commercially available exoskeleton walking device in Asia.
And already researchers are developing biomedical technologies such as myoelectric devices that can be implanted directly into the muscles to control prosthesis. One day they may be used to control exoskeletons too. The implants would read impulses from the muscles and send that information wirelessly to an external receiver in the prosthetic limb or exoskeleton. The ultimate goal is to develop devices that could be controlled directly from the brain.
“At this point in time only experimental direct brain to prosthesis interface are available and that is in cases of paralysis not limb amputation,” said Esquenazi. “No doubt this may be a future path for prosthetics.”
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