Hugh Herr now heads the MIT Media Lab’s Biomechatronics group. In this TED talk, you will find him talk about the incredible advances in prosthetics that allow for normal levels of balance and speed as that of the biological ones.
Hugh Herr – Bionics designer
Looking deeply inside nature through the magnifying glass of science, designers extract principles, processes and materials that are forming the very basis of design methodology – from synthetic constructs that resemble biological materials to computational methods that emulate neural processes, nature is driving design.
Design is also driving nature. In realms of genetics, regenerative medicine and synthetic biology, designers are growing novel technologies not foreseen or anticipated by nature.
Bionics explores the interplay between biology and design. As you can see, my legs are bionic. Today I will tell human stories of bionic integration, how electromechanics attached to the body and implanted inside the body are beginning to bridge the gap between disability and ability, between human limitation and human potential.
Bionics has defined my physicality. In 1982, both of my legs were amputated due to tissue damage from frostbite incurred during a mountain climbing accident. At that time, I didn’t view my body as broken. I reasoned that a human being can never be broken. Technology is broken. Technology is inadequate. This simple but powerful idea was a call to arms to advance technology for the elimination of my own disability and ultimately the disability of others.
I began by developing specialized limbs that allowed me to return to the vertical world of rock and ice climbing. I quickly realized that the artificial part of my body is malleable, able to take on any form, any function, a blank slate through which to create perhaps structures that could extend beyond biological capability. I made my height adjustable. I could be as short as five feet or as tall as I’d like. So when I was feeling badly about myself, insecure, I would jack my height up, but when I was feeling confident and suave, I would knock my height down a notch just to give the competition a chance.
Narrow, wedged feet allowed me to climb steep rock fissures where the human foot cannot penetrate, and spiked feet enabled me to climb vertical ice walls without ever experiencing muscle leg fatigue. Through technological innovation, I returned to my sport stronger and better. Technology had eliminated my disability and allowed me a new climbing prowess. As a young man, I imagined a future world where technology so advanced could rid the world of disability, a world in which neural implants would allow the visually impaired to see, a world in which the paralyzed could walk via body exoskeletons.
Sadly, because of deficiencies in technology, disability is rampant in the world. This gentleman is missing three limbs. As a testimony to current technology, he is out of the wheelchair, but we need to do a better job in bionics to allow one day full rehabilitation for a person with this level of injury.
At the MIT Media Lab, we’ve established the Center for Extreme Bionics. The mission of the center is to put forth fundamental science and technological capability that will allow the biomechatronic and regenerative repair of humans across a broad range of brain and body disabilities.
Today, I’m going to tell you how my legs function, how they work, as a case in point for this center. Now, I made sure to shave my legs last night, because I knew I’d be showing them off.
Bionics entails the engineering of extreme interfaces. There’s three extreme interfaces in my bionic limbs: mechanical, how my limbs are attached to my biological body; dynamic, how they move like flesh and bone; and electrical, how they communicate with my nervous system.
I’ll begin with mechanical interface.
In the area of design, we still do not understand how to attach devices to the body mechanically. It’s extraordinary to me that in this day and age, one of the most mature, oldest technologies in the human timeline, the shoe, still gives us blisters. How can this be? We have no idea how to attach things to our bodies. This is the beautifully lyrical design work of Professor Neri Oxman at the MIT Media Lab, showing spatially varying exoskeletal impedances, shown here by color variation in this 3D-printed model. Imagine a future where clothing is stiff and soft where you need it, when you need it, for optimal support and flexibility, without ever causing discomfort.
My bionic limbs are attached to my biological body via synthetic skins with stiffness variations that mirror my underlying tissue biomechanics. To achieve that mirroring, we first developed a mathematical model of my biological limb. To that end, we used imaging tools such as MRI to look inside my body to figure out the geometries and locations of various tissues.
We also took robotic tools. Here’s a 14-actuator circle that goes around the biological limb. The actuators come in, find the surface of the limb, measure its unloaded shape, and then they push on the tissues to measure tissue compliances at each anatomical point. We combine these imaging and robotic data to build a mathematical description of my biological limb, shown on the left. You see a bunch of points, or nodes. At each node, there’s a color that represents tissue compliance. We then do a mathematical transformation to the design of the synthetic skin shown on the right, and we’ve discovered optimality is where the body is stiff, the synthetic skin should be soft, where the body is soft, the synthetic skin is stiff, and this mirroring occurs across all tissue compliances.
With this framework, we produced bionic limbs that are the most comfortable limbs I’ve ever worn. Clearly in the future, our clothing, our shoes, our braces, our prostheses, will no longer be designed and manufactured using artisan strategies, but rather data-driven quantitative frameworks. In that future, our shoes will no longer give us blisters.
We’re also embedding sensing and smart materials into the synthetic skins. This is a material developed by SRI International, California. Under electrostatic effect, it changes stiffness. So under zero voltage, the material is compliant. It’s floppy like paper. Then the button’s pushed, a voltage is applied, and it becomes stiff as a board. We embed this material into the synthetic skin that attaches my bionic limb to my biological body. When I walk here, it’s no voltage. My interface is soft and compliant. The button’s pushed, voltage is applied, and it stiffens, offering me a greater maneuverability of the bionic limb.
We’re also building exoskeletons. This exoskeleton becomes stiff and soft in just the right areas of the running cycle to protect the biological joints from high impacts and degradation. In the future, we’ll all be wearing exoskeletons in common activities such as running.
Next, dynamic interface. How do my bionic limbs move like flesh and bone? At my MIT lab, we study how humans with normal physiologies stand, walk and run. What are the muscles doing, and how are they controlled by the spinal cord? This basic science motivates what we build. We’re building bionic ankles, knees and hips. We’re building body parts from the ground up. The bionic limbs that I’m wearing are called BiOMs. They’ve been fitted to nearly 1,000 patients, 400 of which have been U.S. wounded soldiers.
How does it work? At heel strike, under computer control, the system controls stiffness to attenuate the shock of the limb hitting the ground. Then at mid-stance, the bionic limb outputs high torques and powers to lift the person into the walking stride, comparable to how muscles work in the calf region. This bionic propulsion is very important clinically to patients. So, on the left you see the bionic device worn by a lady — on the right a passive device worn by the same lady that fails to emulate normal muscle function — enabling her to do something everyone should be able to do, go up and down their steps at home.
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