Qing Guo, Yi Zhang, and Dan Jiang
Lower extremity exoskeleton, human–machine coordinated motion, hydraulic displacement control, gait identification, aid-force
In this paper, a human–machine coordinated control approach is presented in lower extremity exoskeleton. Based on the motion of human motion, walking gait is divided into five sub-phases. After structural parameter synthesis for the exoskeleton, the dynamic model that describes the human–machine coupled motion is derived for analysing the variable pressure of hydraulic cylinder. Then a feedback control law is designed in frequency domain to achieve the cylinder position tracking and guarantee the aid-force effect of the exoskeleton. Simulation results demonstrate that the resulting exoskeleton can strengthen the load capacity of one person, with more than 70% aid-force efficiency in the walking stance phase, and that the system response is further improved when the exoskeleton tracks the person. Furthermore, the developed control law is experimentally verified by the human–machine coordinated motion with 50 kg load.
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