A novel variable stiffness scotch yoke series elastic actuator for enhanced functional stiffness

This paper presents a new design and modeling of a novel variable stiffness scotch yoke series elastic actuator (VSY-SEA) mechanism that can achieve variable stiffness values with a linear relationship between torque and displacement. The main goal of this study was to design the yoke’s shape in the scotch yoke mechanism for a system with the desired stiffness. The word “variable” in VSY-SEA does not simply mean that the system has different random stiffness, but rather that the system has the stiffness of the functional form desired by the designer. Yoke shapes in the scotch-yoke mechanism were designed by calculating the relationship between external torque and rotation angle of VSY-SEA, and the simulations were performed using CAD models with various yoke designs. A prototype of the model was built and the calculations were verified through experiments.