Research On The Key Technologies Of MRI-guided Surgery Robot For Prostate Needle Placement

This paper aims to design and manufacture a high precision MRI-compatible robot for prostate needle-insertion surgery. After analyzing design requirements of MRI-compatible robot, three virtual prototypes are designed by Solidworks. By setting the evaluation index, the optimized robot was selected. For the selection of the optimal configuration of the robot, its key technologies are discussed deeply. The main contents of this paper are as follows:To begin with, according to the requirements of confined space of MRI-compatible robot, three magnetic resonance-compatible surgical robot prototypes were designed, and their detailed structure are discussed. Three different kinematic analysis methods are carried on these MRI-compatible robots. According to the results of kinematic analysis, the reachable workspaces of these robots are calculated. According to the concept of condition number, the kinematic dexterity of MRI-compatible robots is compared. Finally, based on the magnetic resonance compatibility and accessibility of control, the third generation of tendon-based MRI-compatible robot was chosen as the optimal configuration.Then, as to the third generation of tendon-based MRI-compatible robot which was chosen, a simple model is presented to demonstrate the basic behavior of the tendon-sheath driving system. The application of Adams software makes a contribution to the result of model in which orthogonal test is used to determine the main factors that influence the accuracy of tendon-based transmission system. Finally, we make a compare of the results between the simulation and mathematic model to draw a conclusion that the tendon-based transmission possesses the sufficient accuracy and reliability for the MRI surgical robot.Finally, in terms of the third generation of robot, the statics and stiffness analysis are discussed. With the use of the principle of virtual work, and delay of tendon in the transmission process, the adjustment amounts of actuators are obtained. Based on the principle of kinematics, the error model considering the input errors, form and position errors of the revolute joints, main parts of the manipulator and the tendons is established. Given a series of certain values of the error source mentioned above and a certain trajectory of the surgical needle tip which is based on kinematics in the reachable workspace, the comparative result of the trajectory based on the error model is obtained. Finally, the experiment is conducted to verify the veracity of the error model.