Work-sharing of Upper and Lower Limbs (WULL) to Assist Ambulatory Movements

Mobility assistive devices, such as canes, crutches or walkers, are used to aid in the mobility of those affected by a lower limb impairment or disability. Some limitations to these devices are that they are hard to use on stairs or on uneven terrains, and add strain on shoulders and back. Powered wearable devices for mobility assistance, such as exoskeletons or exosuits, have been developed and evolved over the past few decades; however, they are generally expensive, bulky, heavy, and power-demanding. A new approach to assist lower limb motions using upper limb muscles was conceptualized and tested using the Work-sharing of Upper Lower Limbs (WULL) device. This device creates external mechanical pathways to transfer upper limb joint motion or force to the lower limb joints. It provides a self-regulated and self-powered means to assist lower limbs during ambulatory movements using upper limb muscles. The experimental validation of the proposed concept was conducted through a pilot study which showed the kinematics coupling between the paired joints of upper and lower limbs, and the reduction in the lower limb muscle work (electromyography) during several ambulatory movements (e.g., sit to stand and step up) using upper limb muscles. The presented preliminary results show an average of 14% reduction of the rectus femoris activity, which warrants further investigation to validate its efficacy and effectiveness through a larger sample size study involving gait and to identify optimal upper-lower limb joint pairing strategies.