Research On Kinematic Algorithms Of Laparoscope Visual Window And External Force Sensing Of Micro Instrument For Invasive Surgical Robot

Comparing with the traditional invasive surgery,the advantages of robot-assisted minimally invasive surgery include positioning target accuracy,realizing the minimally invasive surgery easily,performing master-slave control and remote operation;it has established the technical foundation for the third generation of surgical operation with minimally invasive characteristics and refinement features,it can significantly to improve the success rate of surgery,to reduce the surgical patients pain,to shorten recovery time.However,the current common problems include simplex movement techniques for the multiple arms system,lack or application difficulties of the force sensing micro instruments,tedious of the operation processes,long time of the preoperative preparation,etc.It has great significance to study on the related kinematic methods and the force sensing technologies for the“intelligentization and autonomization” developments of surgical robot.This dissertation is supported by the National Natural Science Foundation of China(NSFC)(61203358/F0306)and the major project of Fundamental Research Funds for the Central Universities(HEUCFZ1214),the content of this dissertation focuses on two key problems: the laparoscope visual window's kinematic algorithms and the micro instrument's external force sensing of the minimally invasive surgical robot;the detailed theoretical analyses and experimental studies have been carried on the kinematics and dynamics modeling of execution system,the automatic tracking strategy and kinematic algorithms of the laparoscope visual window,the dynamics modeling of flexible driven micro instrument,the indirect estimation strategy of micro instrument's external force and so on.Firstly,the composition characteristics of minimally invasive surgical robotic system have been analyzed,as well as the structure characteristics of 8 degrees of freedom(DoF)laparoscope arm and 11-DoF instrument arm of execution system;based on a kind of combined perform system with three arms,the forward/inverse kinematics models have been established based on the unified base coordinate system,and the simulation analyses and verifications have been completed,and these studies play the foundation of the automatic tracking algorithms of laparoscope visual window;furthermore,the dynamic models of the active joints of laparoscope and instrument arms has been established by using Lagrangedynamic equation,respectively,and simulation analyses have been studied in the Simulink environment of Matlab software.Secondly,in order to achieve the automatic tracking ability of laparoscope visual window,the automatic tracking kinematic algorithms of visual window have been studied;based on kinematics models of the muti-arms execution system,the relative motion relations between the instrument arms' mark points and laparoscope visual window has been deeply analyzed,and an automatic tracking algorithm has been proposed based on the presupposed view parameters of visual window,the simulation analyses and verifications has been studies by using two groups of planned trajectories and two groups of actual trajectories from the master manipulator;meanwhile,in order to reduce the hysteresis effect in the window tracking,and to improve the tracking consistency of visual window and synchronicity of operation,on the basis of the GM(1,1)and Grey Verhulst Model prediction Models,supplemented by adaptive setting method of weighted values,a kind of composite grey prediction model has been proposed with a correction algorithm of predicted trajectory,such that a kind of automatic tracking kinematic algorithm of the laparoscope visual window has been established based on the composite prediction model,the feasibility and effectiveness of the algorithm are verified through the simulation analyses.Thirdly,for solving the problem of the contact force and clamping force detection of3-DoF micro device's wrist,the characteristics of the mechanical model of wrist's driving mechanism has been deeply analyzed,and an equivalent experimental system prototype has been set up for studying the contact force and clamping force,and a kind of indirect force sensing method has been proposed based on the tension changes of wire-driven.The kinematics and dynamics models of the wire-driven wrist joints has been established,respectively;and a force estimation strategy has been proposed based on “comprehensive resistance changes of the driving system”;the comprehensive resistance experiments of wrist joints have been studies under the free motion,and then the neural network models of joints' comprehensive resistance have been obtained by using the BP neural network with nonlinear fitting method;the estimation strategies of the pitch and deflection joints' contact force and the forceps' s clamping force have been proposed by independent analysis method,the estimation performance and precision of the two-dimensional external force and clamping force have been verified through experiments,these relults could support of theory andtechnology for the multidimensional force and clamping force detection at the end of micro instrument.Finally,in order to improve motion control precision and external force detection ability of the micro instrument,a new kind of 4-DoF micro instrument configuration has been proposed based on elastic wire-driven,and the indirect estimation strategy and scheme of 3dimensional external force and clamping force have been studied.An elastic wire-driven unit of single joint is treated as the study object,the parameters identification of dynamic model has been studied,and a kind of joint angle estimator has been designed,it can hep to realize the closed loop feedback position control for improving the precision of motion control;meanwhile,the disturbance estimator of traction wire-driven tension has been designed,and then a kind of joint external force disturbance observer has been designed with the no-load compensation algorithm.The joint motion tracking and external force extamination experiments have been carried out,the joint position closed-loop control and external force detection have been verified by the experiment results,and these key technologies could play the foundation for further development of 4-DoF micro instrument with force sensing ability.