A Biologically Inspired Lower Limb Cable Driven Exoskeleton

The lower limb exoskeleton has been widely applied in different fields, such as rehabilitation, training, and the military, which generally improves the performance of subjects. This paper developed a lower limb cable-driven soft exoskeleton to assist walking called MCR Exo. The exoskeleton is mainly combined by a two-layer structure: passive and active layers. The passive layer is made of elastic material and worn by the users, just like tights. Meanwhile, the active layer is composed of an actuator and Bowden cable attached to the passive layer to supply the assistant force. The two-layer structure is arranged corresponding to the muscle group distribution that produces the largest force in the gait cycle. The exoskeleton can detect five gait events based on artificial neural networks (ANN) and determine the gait cycle. Meanwhile, the MCR Exo would supply a torque up to 10.7 Nm, and the torque profile is designed based on the lower limb muscle force patterns. A human trial experiment is conducted to analyse the performance of the MCR Exo by measuring the surface electromyography (sEMG) of lower-limb muscles during walking. The MCR Exo can achieve the largest muscle activity (%MVIC) reduction at 5.90% in soleus (SO), 2.20% in gastrocnemius medialis (GM) and 2.05% in Gastrocnemius lateralis (GL) compared with walking without Exo.