Abstract: An assistance device is described to assist a joint motion of a lower limb. The assistance device includes a driving part, an elastic part, and a crank mechanism. The driving part includes a motor and a transmission mechanism to change a speed of the motor and converts a rotational motion of the motor into a linear motion. The elastic part includes at least: a series spring provided in series between the transmission mechanism and the crank mechanism, a first parallel spring provided between the driving part and the ankle part, and a second parallel spring provided between the ankle part and the foot part. The crank mechanism is provided between the driving part and the foot part and converts the linear motion to a rotational motion while changing a deceleration coefficient according to an ankle angle.

Abstract: A knee coupling may be an assist device for assisting the movements of a knee joint. Specifically, a knee coupling may include: a ball screw that converts the rotation of a screw shaft rotated by a motor to the linear motion of a nut; a linear motion member that is provided coaxially with the screw shaft and moves along the screw shaft along with the nut; an elastic member that is provided coaxially with the screw shaft to intervene between the nut and the linear motion member; and a crank mechanism that converts the linear motion of the linear motion member to rotational motion.