Modelica Model-based Design of Gear Train for Link Mechanism to Move Seat of Sit-to-stand Assist Device

Abstract

The activity of standing up is essential in daily life. Many sit-to-stand assist devices have been developed for people with difficulties standing up, such as elderlies and people with disabilities. We have been aiming to develop a sit-to-stand assist device that can guide the user to a series of postures with less extra burden on each joint of the lower limbs. In previous research, we derived the optimal series of postures during standing up that can minimize the burden suitable for individuals. We also proposed a sit-to-stand assist device equipped with a link mechanism to move the center of the hip joint of the person sitting on the seat in an S-curve trajectory. In this report, by modeling the link mechanism using Modelica, we determined the number of teeth of engaged spur gears composing the link mechanism to have the highest reproducibility of the S-shaped curve trajectory.