Leverage and Parallelogram Mechanism for Robotic Assist in Open MRI Guided Surgery Kinematics, Workspace Analysis, and Stiffness Evaluation

摘要

We would propose a novel mechanism of a surgical manipulator, which works in Open MRI guided surgery and assists surgeon (s) in precise positioning and handling of surgical devices. This mechanism can transmit 3 translational and 3 rotational motions from the outside to the inside of MR imaging area by using leverage and parallelogram mechanism. Such a remote actuation is significantly helpful because the strong and sensitive magnet of MR denies the accessibility of magnetic and electric devices and materials to the imaging area. In this paper, the basic ideas of mechanism were introduced and its forward and inverse kinematics was formulated firstly. Secondly, a non-MR-compatible prototype was made to reveal mechanical problems. Thirdly, the workspace of the prototype was numerically analyzed. Fourthly, the stiffness of the prototype was experimentally evaluated. These results concluded trade-off between stiffness and workspace. Fifthly, our new idea of workspace control for mechanical safety was preliminary discussed.