Design and Modeling of a 6-DoF Parallel Mechanism for MRI-guided Surgery

Surgical operation based on MRI image guidance is currently widely used in the medical field, which has good therapeutic effects for brain nerve surgery, breast, bladder and other puncture surgery. However, due to the limitations of the MR environment, conventional surgical assisted robots cannot be applied. Hence, an MRI-compatible actuated robot is required. Currently, there are various designs of MRI-compatible surgical robots, but adequate room exists for improvement and optimization in terms of structure, size, and driving mode of the mechanism. Therefore, considering the characteristics of surgical robots and the application requirements in the MR environment, this paper proposes a parallel mechanism with three branches and six degrees of freedom. Kinematic modeling and differential kinematic analysis are carried out by which the input of the mechanism is linked to the position and velocity of the ends. In addition, a workspace analysis is derived for the proposed mechanism, and the feasibility of the design is verified via simulations. The proposed robot has the characteristics of small size, compact structure, wide workspace and high positioning accuracy, which meets the application requirements of MRI-compatible surgical robots.