Soft wearable exosuit to lighten heavy loads

Harvard scientists have developed a flexible, wearable exosuit that reduces the energy cost of walking when carrying heavy loads and can benefit soldiers, hikers and people with physical impairments.
The researchers found that the exosuit reduced the amount of energy consumed during loaded walking - the metabolic cost - by 7.3 per cent on average.
The suit also significantly reduced the work done by the hip, knee and ankle joints, without impacting step frequency or length.
Hip, knee and ankle movements of walkers carrying a load while supported by the suit were similar to movements measured during unloaded walking, researchers said.

This suggests that the suit does not affect the wearers' freedom of movement, but allows them to return to a walking profile closer to that of people walking without a load.
The device could benefit groups of people who frequently carry heavy loads, such as soldiers, first responders or hikers, according to the researchers. It could also prove useful for people with physical impairments.

Researchers used textiles to build their alternative to rigid exoskeletons, which are heavier and can interfere with the natural movement of the joints, causing the wearer to change the way they walk.
The suit is composed of a waist belt, two thigh pieces and two calf straps, connected by cables to two motors mounted on a backpack.

The energy from the motors travels via the cables to the suit which transfers it to the wearer. The suit becomes active only when it detects a walking motion.
It assists the hip and ankle joints which together contribute about 80 per cent of the power produced by the leg joints during walking.
"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," said Conor Walsh from Harvard University.
"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 in a wide range of people," said Walsh.

The researchers tested their exosuit under three conditions. The unpowered condition had study participants wearing the suit and a full backpack with the suit turned off.
The powered condition had participants wearing the suit and a full backpack with the suit turned on. The third condition was used as a baseline with the suit turned off and the equivalent weight of the suit (6.5kg) removed from the backpack.
Seven experienced load carriers who had no injuries or diseases of their muscles, joints or bones, walked on a treadmill at a constant speed of 1.5 metres per second while carrying a load equal to 30 per cent of their body mass.

The study was published in the Journal of NeuroEngineering and Rehabilitation.