Exoskeletons often fail to allow the wearer to perform natural joint movements, and are also generally heavy, which causes fatigue. For applications where a person only needs partial gait assistance from a robot, researchers from Harvard University's Wyss Institute researchers are pursuing the use of soft, clothing-like "exosuits."
Ongoing work to optimize the suit design and make it portable is being funded by DARPA's Warrior Web Program. An exosuit wearer's bone structure must sustain all the compressive forces normally encountered by the body, plus the forces generated by the suit.
The soft exosuit uses a combination of sensors - including a hyperelastic strain sensor and sensors around the wearer’s hip, calf, and ankle - all secured by straps. Flexible membranes cover sensors and straps.