Design And Simulation Of Haptic Manipulator For Minimally Invasive Robotic Surgery System

The application of master-slave minimally invasive surgical robot in surgery hasbeen widely used and been accepted by the public, which not only reduces the patient’spain and their postoperative recovery time, but also frees the doctor from traditionalminimally invasive surgery. In this way, the quality of the surgery is improved and bothdoctors and patients benefit from this new technology. Haptic manipulator is animportant component of master-slave minimally invasive surgical robot and is also thecarrier of the information transfer as well as the human-computer interaction between thedoctor and the robot. Its performance directly influences the whole performance ofminimally invasive surgical robot system. Currently, haptic manipulators sold on themarket are mostly universal, which couldn’t well meet the specific requirements of therobotic minimally invasive surgery. Therefore, it is very necessary to design a hapticmanipulator especially for minimally invasive surgical robot.Based on the analysis of minimally invasive surgical robot’s actual requirements onhaptic manipulator, this dissertation carries out the manipulator’s configuration design. Ithas6+1degrees of freedom, a3degree-of-freedom translational mechanism obtainingthe position information, a3degree-of-freedom rotational mechanism obtaining theangle information and a1degree-of-freedom clamping mechanism controlling the openand close operation of the surgical instrument. The translational mechanism andclamping mechanism can realize the force feedback, the force is applied to doctor’s handthrough the motor’s output torque and wire transmission. Then, according to the selectedconfigurations and force feedback principle, detailed mechanical design of the hapticmanipulator is carried out. The designed manipulator has functions such as zeropositioning, safety limit, force feedback, gravity compensation and so on.Using completed configuration of the manipulator, forward and inverse kinematicanalysis of translational mechanism and forward kinematics of rotational mechanism isdeduced. The Jacobian matrix is derived through mapping from the joint velocity tooperating velocity. Optimization of translational mechanism’s size is finished based on itsperformance index. The mechanism’s dexterity and manipulability is analyzed and itswork space after optimization is obtained. In finite element analysis software, the staticstiffness analysis of haptic manipulator is conducted.With some simplification of the mechanism model, its dynamics is analyzed. Thedynamic model is established using the principle of virtual work. The force Jacobianmatrix is defined and the mapping from joint motor output torque to the force felt at theend of the manipulator is created. In this way, theory foundation of force feedback’simplementation is obtained. Based on the dynamic model, PD control is chosen as the force feedback control method, which realizes the closed loop control process. Insimulink, trajectory tracking of a simplified single joint is completed, which verify theeffectiveness of the control method.Finally, the manipulator’s virtual prototype is established in ADAMS. Using givenjoint drive functions to run the prototype, driving torque is measured. Compared withresult obtained from the dynamic equation, the validity of dynamic model is proved.Chosen a cylindrical spiral line as the manipulator’s desired trajectory, simulation isconducted by ADAMS and MATLAB combined with kinematics and dynamics analysisresults. This proves the correctness of the theoretical analysis in this dissertation. Takengravity term of the dynamic equation as the motor torque, gravity compensation’seffectiveness is tested in given test points by simulation.