The exosuit in action. (Credit: Harvard Biodesign Lab) Exosuits may seem the stuff of anime and superhero movies, but the technology is actually used for assisting those who might need a boost to go about their daily lives. These wearable technologies fit onto the body, usually the legs, much like a high-tech wetsuit. The exosuit is designed to provide supportive force to various points of the leg when needed, helping the user walk more easily and naturally. Now, new research out of Harvard University published in Science Robotics shows the potential for exosuits to adapt to their users in real-time, accounting for minor changes in gait as the user walks.
One Size Doesn’t Fit All
To give the most benefit, these wearable technologies have to be perfectly in sync with a user’s unique physiology and movement patterns. This is challenging, because every person has a unique gait that’s dependent on their anatomy, age, presence of injuries or illness and even personality. An exosuit’s design and programming may work flawlessly for one person, but actually inhibit movement in another. Building an adaptable exosuit, one that responds to variations in gait and movement, is the best way to deal with the broad range of human bodies that such technology will inevitably encounter. The challenge with current optimization methods is that they take a great deal of time and observation in order to create. A subject would need to walk repeatedly in order to establish a rough approximation of their movement patterns — which, even then, would not account for changes that might occur as a user is walking. What the new suit does is adapt to the user’s movements quickly. This is important, because humans actually make tiny adjustments to their gait while walking to maximize efficiency. By measuring these changes, the researchers were able to build profiles for each user that told the exosuit when and where to give them a boost.
Walk the Walk
The exosuit the researchers worked with fits snugly around the waist and thighs, and helps to optimize hip extension when walking. It’s more subtle than a full-on robotic leg, but the goal here is efficiency, not power. Eight adult male subjects walked on a treadmill while wearing the suit while a computer monitored their movements. The researchers refer to this as a “human-in-the-loop” model of optimization because it depends on constant input from users to refine its calculations. An optimization algorithm updated how the suit applied force after each cycle, gradually locking in ideal motions for each subject. After about 20 cycles, the computer had created personalized "profiles" for each participant. All of that research and math is nice, but what’s the point? Well, the optimized exosuits reduced the users’ metabolic output by a total average of 17.4 percent compared to walking without the suit—a 60 percent improvement over existing exosuits, the researchers say. Individualizing exosuits is another step toward bringing them into our lives. But for now the math and processing required for such a personalized touch requires that the suit be in constant communication with a nearby computer — not so great for mobility. But as we all know, computers are getting smaller and more powerful every day. Next stop, Neon Genesis Evangelion — or Iron Man, take your pick.