Research on preoperative positioning analysis of instrument arms for minimally invasive surgical robot

This paper presents a preoperative positioning method, in order to realize the applicable preoperative position of instrument arms of minimally invasive surgical robot, which is consisted of two instrument arms and one laparoscope arm. Firstly, the kinematics model of instrument arm´s fixed point (surgical pointcut of the trocar) is established, the forward and inverse kinematics are calculated out as the basic equations; secondly, the kinematics relationship of instrument arms´ passive joints are studied, and the projection length and area determination conditions are proposed with detailed equations, in order to judge and filtrate the good results of instrument arms´ preoperative positioning angles; thirdly, the percentage of collaboration workspace of the two instrument arms is used to judge the best preoperative positioning angles. Finally, a serial of numerical simulation analysis are finished by using Matlab software; the simulation results are presented to illustrate the correctness and the feasibility of the preoperative positioning method of the two instrument arms.