According to its developers, the exoskeletons helped the wearers maintain appropriate lifting postures even when fatigued, thus showing promise for preventing workplace injuries.

Making this possible is that the researchers focused on strengthening the wearers’ legs to maintain proper lifting form instead of bracing the back and thus compromising posture.

Source: University of Michigan

To make that determination, the researchers recruited volunteers to test the exoskeletons, instructing them to perform lifting and carrying tasks using a 20 lb kettlebell.

Volunteers were instructed to lift the kettlebell from the ground, carry it on flat ground, up and down an incline, and stairs. The researchers suggested that as the volunteers became fatigued, the exoskeleton helped them to maintain better posture and lift faster; reportedly just 1% slower than their normal pace, versus 44% slower without the exoskeleton.

Participants reported being mostly satisfied or very satisfied, except when they walked on level ground, where their satisfaction was more moderate. The team added that the comfort of the exoskeleton is due to its motors and gearing, which enables the wearers to swing their knees naturally. Additionally, the software predicts the assistance necessary by measuring the knee joint angle, the positions of the thigh and lower leg, and the force identified by a sensor located in the user’s shoe.

The system analyzes those three measurements from both legs, which enables it to determine the user’s intended motion along with the amount of assistance needed. The measurements are taken 150 times per second, thus enabling the exoskeleton to transition smoothly between activities.

An article detailing the team’s findings, “A Versatile Knee Exoskeleton Mitigates Quadriceps Fatigue in Lifting, Lowering, and Carrying Tasks,” appears in the journal Science Robotics.