Compact Variable Stiffness Actuator for Surgical Robots

Highly rigid surgical robots are capable of precise po-sitioning; however, there is a risk of injury to the sur-rounding organs owing to undesired contact. To solve this problem, surgeons can change their stiffness according to the desired motion by contracting and re-laxing the muscles. Therefore, surgical robots that can change their stiffness according to their application, similar to a surgeon, are useful in improving safety. However, existing variable stiffness actuators cannot easily achieve a wide variable stiffness range while maintaining a small size and lightweight, which are critical factors for surgical robots. This study presents the design, fabrication, and evaluation of a variable stiffness actuator that is compact and provides a wide range of variable stiffness, with elastic elements ar-ranged in a circumferential direction.