If you've ever lugged a heavy pack cross-country, you may have idly dreamed of a suit that would carry some of the weight for you. Now engineers at Harvard have made the dream a reality, albeit a somewhat less dramatic prototype than may have been imagined
The Journal of NeuroEngineering and Rehabilitation describes a flexible exoskeleton made up of a waist belt, thigh pieces and calf straps, driven by motors carried in a backpack.
The suit doesn't walk by itself. Instead, when sensors detect that the wearer is walking, the motors drive the leg pieces, causing them to move in sync with the wearer, taking part of the load. The exosuit was found to reduce the metabolic cost of walking for seven volunteers by an average 7.2 percent, even allowing for the weight of the motors.
To become worthwhile, the 7.2 percentage will have to rise substantially, but the paper outlines plans for that, and senior author Dr. Conor Walsh said in a statement: "Our results demonstrate for the first time that an autonomous soft exosuit can reduce the energy expenditure experienced by load carriers, possibly enhancing their overall gait performance."
Walsh added: "Apart from assisting load carriers, we are exploring how the soft exosuit can be used to assist individuals with impaired movement, paving the way for the use of this technology by a wide range of people."
As the paper notes, “Prolonged load carriage can result in an increased risk of injury... Solutions that effectively reduce the burden associated with load carriage during walking are thus warranted.”
The suit in its eventual intended environment. Wyss Institute at Harvard University
To make comparisons more reliable, the experiment was conducted on a treadmill moving at a constant 1.5 meters (5 feet) per second rather than on the rough walking tracks where such a machine is likely to be most popular.
Participants carried a backpack weighing 30 percent of their body weight and tested it under three conditions: the suit with the motors turned on, the suit with the machine turned off, and the same backpack but with the 6.5-kilogram (14.3 pounds) motors removed. Metabolic cost was measured by oxygen consumed and carbon dioxide released.
In the tests, participants consumed 11 percent less energy when the motors were turned on than when they were off but still being carried. More importantly, there was still a reduction when compared with wearing a pack lightened by the absence of the motors, proving that even in its trial state the suit is more help than hindrance.
Crucially, the soft exoskeleton allowed wearers to move naturally, reducing fatigue. Past efforts with lower limb exoskeletons have involved rigid structures that force the wearer to walk like a robot – cool on the dance floor, but not much fun over a long hike.
By making their suit out of textiles, Walsh's team not only made it conform to the wearer's gait, but lightened the weight.
Still not as cool as Ripley's powerloader though.
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