2A1-A04 Proposal of A Test Method Using A Lower-Limb Dummy for Human Wearable Robot Safety : 1^<st> Report: Proposal of A Lower-Limb Dummy with A Mechanism of 1 Translation Motion in Conjunction with Knee-Joint Rotation(Robotics with Safety and Reliability)

Test method for contact safety assessment of a wearable robot -analysis of load caused by a misalignment of the knee joint-

“…Therefore, in this study, a risk assessment of a wearable robot was conducted. A lower-leg dummy was also developed for the safety tests [5], [6].…”

“…Therefore, the femur slides on the tibia when the knee is bent. As a result of this composite motion, the center of rotation moves with the bending angle [5], [8], [9], [10], [11], [12]. In contrast, the knee joint of a general wearable robot consists of a pin joint.…”

“…Many studies have suggested that the center of rotation in the human knee joint moves with a bending of the knee [5], [8], [9], [10], [11], [12]. However, these studies have focused only on the knee joint itself.…”

“…As the initial misalignment, two parameters, dx and dy, are used, since the effect of a misalignment differs according to the direction. A displacement of the cuff position is calculated using (5). As a result of this calculation, a misalignment in the backward or upward direction increases the displacement toward the centrifugal (plus) direction, while a forward or downward misalignment has the opposite effect.…”

“…Geometry of lower leg model to simulate the misalignment of rotation axis Geometry of lower leg model in sagittal plane the sagittal plane causes a displacement of the cuff position in the longitudinal direction of the lower thigh with a bending of the knee.Equations (1)-(5) calculate the displacement between the cuff positions of the wearable robot and the user at the sagittal plane of the wearable robot. A bending of the knee shortens the length between the center of the knee joint and the cuff location.…”