Analysis of Lower Extremity Shape Characteristics in Various Walking Situations for the Development of Wearable Robot

A strap is a frequently utilized component for securing wearable robots to their users in order to facilitate force transmission between humans and the devices. For the appropriate function of the wearable robot, the pressure between the strap and the skin should be maintained appropriately. Due to muscle contraction, the cross-section area of the human limb changes according to the movement of the muscle. The cross-section area change causes the change in the pressure applied by the strap. Therefore, for a new strap design to resolve this, it is necessary to understand the shape change characteristics of the muscle where the strap is applied. In this paper, the change in the circumference of the thigh and the calf during walking was measured and analyzed by multiple string pot sensors. With a treadmill and string pot sensors using potentiometers, torsion springs, and leg circumference changes were measured for different walking speeds and slopes. And, gait cycles were divided according to a signal from the FSR sensor inserted in the right shoe. From the experimental results, there were changes in the circumference of about 8.5mm and 3mm for the thigh and the calf, respectively. And we found tendencies in various walking circumstances such as walking speed and degree of the slope. It is confirmed that they can be used for estimation algorithms of gait cycles or gait circumstances.