A Clutchable Unpower-Assisted Device with Adjustable Variable Stiffness

The unpower-assisted device is an essential part in the development of exoskeleton robot, and it can provide additional mechanical energy for the movement of human joints, so that enhance the function of human body, especially the knee joint. According to the kinesiology of the human lower limb, the gait characteristic of knee joint can be studied, and a clutchable unpower-assisted device is presented in this paper for the knee exoskeleton with the function of adjustable variable stiffness. The clutchable performance of the unpower-assisted device is in on state and store the mechanical energy through the knee flexion, while it is in off state and generate the human-like variable stiffness in knee extension, so that the exoskeleton can assist the wearer to walk relaxed and naturally. Besides, the simulation-based kinematic and dynamic verification is carried out for the unpower-assisted device through the human-exoskeleton model. The device has the advantages of lightweight and compact structure, and the results show that the device can generate a human-like joint stiffness during the movement of knee flexion-extension, and which can be used as the unpower-assisted device for the passive knee exoskeleton.