Propulsion during push-off is the key to realizing human locomotion. Humans have evolved a way of walking with high energy utilization, but it can be further improved. Drawing inspiration from the muscle-tendon unit, a passive spring-actuated ankle-foot exoskeleton is designed to assist with human walking and to lengthen walking duration by mechanically enhancing walking efficiency. Detection of the gait events is realized using a smart clutch, which is designed to detect the contact states between the shoe sole and the ground, and automatically switch its working state. The engagement of a suspended spring behind the human calf muscles is hence controlled and is in synchrony with gait. The device is completely passive and contains no external power source. Energy is stored and returned passively using the clutch. In our walking trials, the soleus electromyography activity is reduced by as much as 72.2% when the proposed ankle-foot exoskeleton is worn on the human body. The influence of the exoskeleton on walking habits is also studied. The results show the potential use of the exoskeleton in humans' daily life.
Rehabilitation with exoskeletons after hip joint replacement is a tendency to achieve efficient recovery of people to rebuild their human motor functions. However, kinematic mismatch between the kinematic and biological hip is a problem in most existing exoskeletons that can cause additional stress in the hip. To avoid secondary damage, the misalignment between the mechanical and biological hip joint of an exoskeleton must be compensated. This paper introduces a novel hip exoskeleton system based on parallel structure. The exoskeleton can inherently address the kinematic mismatch by introducing additional kinematic redundancy, while requiring no additional kinematic components and volumes. To achieve bidirectional full-gait-cycle walking assistance, a remote actuation system is designed for power delivery. A control scheme is designed to reject disturbances caused by gait dynamics during walking exercises. Human testing was carried out to evaluate the performance of the system. The results show that the exoskeleton has good human-machine kinematic compatibility and can achieve promising force tracking in the presence of gait dynamics.
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