Design of a Needle Guidance Based a Variable Stiffness Continuum Manipulator for Brain Surgery

Owing to their continuously bending backbone, continuum robots are able to perform dexterous movements and accurate manipulation, allowing them suited for unstructured environments such as surgical applications. However, controlling their stiffness and payload capability are still challenging. This paper presents a novel design of continuum robot for needle guidance in brain surgery. The design composes of a series-connected rigid spherical joints, and a central cable acting as a backbone to adjust stiffness of the robot. Additionally, this cable offers a mechanical lock to precisely reach the target pose for the needle during Intracerebral Hemorrhage (ICH) evacuation surgery. A design studies are conducted by optimizing certain parameters to evaluate the performance of the robot in terms of variable stiffness and locking. The design analysis is performed, while respecting the constraints of stress and deflection. On the other hand, a friction analysis based on contact point estimation approach is derived to ensure the configuration lock. The performance of the proposed design is evaluated by using Multibody Dynamics software. Moreover, experimental validation of the robot is carried out to verify its variable stiffness and payload capacity. The results demonstrate that the continuum robot has an acceptable load-carrying capacity and displacement deflection error. The displacement deflection error range from 0.78 mm to 0.48 mm at payload of 500 gm and tension force range from 350 N to 800 N.