Design And Optimization Of Remote-center Mechanism For Minimally Invasive Surgical Robot

By comparison with the traditional open surgery, Minimally Invasive Surgery (MIS)has the advantages of smaller trauma, less patient-pain and shorter postoperative recovery,helping improving surgery quality and safety as well as reducing medical cost, which isbecoming an inexorable trend of modern surgery. Minimally invasive surgical robot is anew cross-research field set by many disciplines. Owing to its application, deficiencies ofnormal minimally invasive surgery are conquered, not only reducing the surgeon’sworking intensity, but also enhancing the quality of operation significantly. Consequently,it has been attracting widespread attentions in recent years and is becoming one of themost popular research areas in Robotics Field.Under the background of the National863high-tech project "Common keytechnology and demonstration application on minimally invasive celiac and thoracicsurgical robot", this article discussed the detailed mechanical design, optimization andrelated technical research of the remote-center mechanism, which is the core ofminimally invasive celiac surgical robot.Firstly, the structure of the remote-center mechanism is designed. Based on theclinical requirement and motion freedom of minimally invasive surgery, the finalconfiguration of the manipulator is determined. A new type of remote-center mechanismis presented and its detailed mechanical structure is designed. According to the forcesituation of the mechanism during the surgery, the static analysis and the sectionparameter optimization are carried out. Moreover, servo-motors are selected dependingon the needs of real surgeries.Secondly, the kinematics and dynamics of the manipulator is analyzed. The forwardand inverse kinematics is solved by D-H notation and inverse transform method toestablish the working space of the manipulator. On this basis Jacobian matrix iscalculated using vector product method. In addition, Lagrangian method is applied toanalyze the dynamics, with simulations verifying its validity.Thirdly, by analyzing several performance indicators of the remote-centermechanism which are based on conditional number, its configuration is optimized. Thedimensions of the passive joints are optimized on the goal of the operability to improvethe flexibility of the manipulator.Finally, in view of the minimally invasive surgery process, ADAMS is utilized to simulate motions of the entire manipulator and typical motions of the remote-centermechanism. The actual moving effects show the rationality of the dimensionaloptimization and the effectiveness of the remote-center mechanism design.