Design and Control of a Flexible Exoskeleton to Generate a Natural Full Gait for Lower-Limb Rehabilitation

Strokes caused by cerebrovascular diseases often result in severe damage to locomotion, movement, and cognitive functions. Rehabilitation is an effective way to regain locomotion ability in daily life. However, there are mismatching biological joints, non-full rehabilitation gaits, and indirect joint feedback among conventional exoskeletons or devices. Hence, this paper proposed a novel flexible Bowden cable driving exoskeleton to achieve natural full walking gaits utilizing direct lower-limb movement feedback. First, complete flexible joint rotation kinematics was proposed by using a pair of agonism-antagonism flexible Bowden cables. Then, a personalized rehabilitation walking gait and feedforward proportional-integral-differential controller were adopted to drive the lower limbs to realize complete joint movement and natural full gait locomotion. Finally, a prototype was designed to verify the effectiveness. Mannequin and human tests were conducted, and the results show that the real walking gait is consistent with the reference natural human gait and that assistive torque was applied to humans to reduce muscle activation without significantly changing the foot pressure.