Research On Redundant Robot Arm For Minimally Invasive Surgery

Robot-assisted minimally invasive surgery (RMIS) has attracted broad interests all around the world and achieved fast development, for its great advantages of small incise, high precision and high dexterity, as well as increasing the quality and safety of the surgery, extending the ability of the surgeon and improving the working environment of the surgeon. Robotic surgery system is a new multidiscipline research field, which has great social value and economic profits. This paper carries out the research on the robot arm for minimally invasive surgery, based on the National 863 high-tech project"Minimally Invasive Surgical Robot".Firstly, the configuration of degree of freedom (DOF) and structure type are designed based on the analysis of the working environment of minimally invasive surgery and the requirements of the robot arm. The robot arm includes three parts, which are arm position mechanism, instrument position mechanism and instrument interface, and their mechanical structure is designed in detail.Secondly, the forward kinematics is established based on D-H notation, and the inverse kinematics is solved by inverse conversion method according to the structure and working state of the robot arm. The movement performance of the robot arm is evalued by the dexterity degree, which are established by Jacobian matrix. And the structural size of the robot arm is optimized, with the dexterity degree as the criteria.Thirdly, the load of joints is analyzed, and its dynamics is simulated by ADAMS, and then the parametes of servo motor are determined. The stiffness and strength of the robot arm are checked by the Finite Element Method. Moreover, the pose planning of dual instrument arms are analyzed based on the improved gradient projection method, with Maximum Distance Criterion (MXDC) as criteria, in order to reduce the collision occurred during the operation.Finally, the experiment platform is set up to test the performance of the robot arm, which includes the prototype of the robot arm and the control system. The experiment mainly tests the ability of manual posing, and active driving as well as the precision of remote center motion, and then the results are analyzed.