Paralyzed Man Walks with Aid of Mind-Controlled Exoskeleton

October 11, 2019 Clive Maxfield

Paralyzed man walks with aid of mind-controlled exoskeleton
Image source: A frame from BBC video

In an earlier column we introduced a tiny (2.5 mm x 0.6 mm) device called Injectsense, which can monitor the pressure inside the eye. In the not-so-distant future, the goal is to use devices like these to provide organ-to-cloud data connections that will allow clinicians and physicians to monitor our health and determine the effectiveness of alternative therapies and drug regimens in real-time.

I closed that column by saying, "We truly do live in interesting times." Well, they are getting more interesting by the minute, because I just heard about a mind-controlled exoskeleton that is helping a paralyzed man walk for the first time since he broke his neck several years ago.

We’ll return to this in a moment, but first I'd like to share a few of the thoughts this has triggered that are currently bouncing around my poor old noggin. The first is the novel The Terminal Man by Michael Crichton, in which a patient called Harry who is subject to violent activity while having seizures has electrodes implanted into his brain. The idea is for a small computer to monitor Harry's brainwaves and apply stimulus to prevent the seizures from taking place. Sad to relate, things don’t work as planned. Although this book is now dreadfully dated (it was published in 1972, only one year after the first commercial microprocessor -- the Intel 4004 -- appeared on the scene), the possibilities it envisages still send shivers running up and down my spine.

My next thought was related to the 1986 American science fiction action film Aliens (the sequel to the original Alien movie from 1979). I'm thinking of the part depicted in this video snippet where the character Ellen Ripley (played by Sigourney Weaver) get's into a Power Loader and soundly chastises the Alien Queen who is attacking a little girl. Who amongst our number can forget Ripley shouting, "Get away from her you naughty creature" (or words to that effect)?

Real-World Power Loaders

The reason I'm waffling on about things like implanting electrodes and power loaders is that it's amazing to me how the stuff of science fiction is evolving into the stuff of everyday life. Take Ripley's Power Loader, for example, and compare it to the METHOD-1 manned robot project by Korea Future Technology.

 

 

Although devices like this are still in the early stage of development, it's not hard to envisage numbers of them being used to quickly and efficiently transport large quantities of building materials around a construction site, for example.

Real-World Exoskeletons

Tetraplegia, also known as quadriplegia, refers to a spinal cord injury above the first (uppermost) thoracic vertebra resulting in the victim being wholly or partially paralyzed in all four limbs. At some stage in the future, medical science may advance to the stage where physicians can repair this sort of injury, but that's probably a long way off. In the shorter term, it may be possible to provide a workable solution using mind-controlled exoskeletons.

As reported in The Lancet Neurology, about four years ago, a former French optician known as Thibault fell and broke his neck, resulting in him becoming a tetraplegic (a.k.a. quadriplegic) and being paralyzed in all four limbs. A team at University of Grenoble Alpes in France set out to get Thibault walking, moving his arms, and manipulating things with his hands by means of a mind-controlled exoskeleton.

Several groups are working on ways in which people with spinal cord injuries can control things using their minds, but these typically involve the invasive technique of embedding an array of incredibly fine electrodes deep into the brain (shades of The Terminal Man). In addition to the possibility of infection, the performance of these electrodes can degrade over time as the body defends itself against their intrusion.

To work around these issues, the team used a semi-invasive approach where two circular sensor devices, each about 5 cm in diameter, replaced portions of the skull on each side of Thibault's head. Each sensor features a grid of 64 electrodes, which press against the membrane that protects the brain. The sensors are then covered by Thibault's skin.

These sensors span the sensorimotor cortex (the area of the brain that controls sensation and motor function). As seen in this video, the resulting signals undergo sophisticated signal processing algorithms that remove noise, determine Thibault's intent, and control the exoskeleton accordingly.

 

 

Of course, all of this is still in the early stages. For example, the exoskeleton currently has to be suspended from an overhead harness to prevent Thibault from falling. On the bright side, there is a tremendous amount of related work that is going on in this area that could be brought into play, including artificial intelligence (AI) and the balancing algorithms used by the latest incarnation of the Atlas robot by Boston Dynamics, which is now capable of performing sophisticated acrobatic routines.

The ideal situation would be for the patient to think what he wants to do at a high level of abstraction (e.g., "walk forward," and "raise right arm" -- but not in words, of course), and for the exoskeleton to make it happen while -- at the same time -- taking care of details like maintaining balance and not walking into things or knocking things over.

Hopefully, it won't be too long before we don’t think anything about seeing people wearing self-powered, self-balancing, mind-controlled exoskeletons strolling around leading full and satisfying lives.

 

About the Author

Clive Maxfield


Clive "Max" Maxfield received his BSc in Control Engineering in 1980 from Sheffield Hallam University, England and began his career as a designer of central processing units (CPUs) for mainframe computers. Over the years, Max has designed everything from silicon chips to circuit boards and from brainwave amplifiers to steampunk Prognostication Engines (don't ask). He has also been at the forefront of Electronic Design Automation (EDA) for more than 30 years.

Well-known throughout the embedded, electronics, semiconductor, and EDA industries, Max has presented papers at numerous technical conferences around the world, including North and South America, Europe, India, China, Korea, and Taiwan. He has given keynote presentations at the PCB West conference in the USA and the FPGA Forum in Norway. He's also been invited to give guest lectures at several universities in the US and at Oslo University in Norway. In 2001, Max "shared the stage" at a conference in Hawaii with former Speaker of the House, "Newt" Gingrich.

Max is the author of a number of books, including Designus Maximus Unleashed (banned in Alabama), Bebop to the Boolean Boogie (An Unconventional Guide to Electronics), EDA: Where Electronics Begins, FPGAs: Instant Access, and How Computers Do Math.

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