Structure Design And Analysis Of Manipulator For Minimally Invasive Robotic Surgery System

With the help of robot, the master-slave minimally invasive surgery is becomingthe development tendency of the surgical operation, because of the small wound, fastrecovery, accurate operation and comfortable operation. Master manipulator, as thehuman interface device of the robot system, is the direct operated object for doctors.Therefore, the property of that affects the function of the whole robot system directly.However, the widely used master devices are imported, universal and over expensive;besides, some technical parameters do not match the requirements from the slave robotvery well. So, it is very important and necessary to research a haptic master deviceapplying to the minimally invasive surgical robot independently.Firstly, the paper designs the overall plan and mechanical structure of the masterdevice. Considering the design requirements and the operating environment, the paperchooses to design a serial and heterogeneous master manipulator with8degrees offreedom. Based on the classical wrist structure with3degrees of freedom, the paperdesigns1redundant degree of freedom to increase the flexibility of the wrist Except the6degrees of freedom for position and posture adjustment; besides, there is1open-closedegree of freedom for grasping operation. After analyzing several configurations ofrobot, the paper completes the structure synthesis of the master manipulator. And then,according to the motor and wire transmission, the device realizes the force feedbackability; and to the clump weight and reverse driving characteristics of the motor, thedevice achieves the gravitational equilibrium function. Based on all of the above, thepaper carries out the detailed structure design and calculates the workspace of themaster by the means of analytic method. On the premise of the satisfied workspaces andflexibility, the structure parameters are obtained with the shortest length as the objectivefunction. All of that make the designed manipulator have the function of boot for zero,safety limit, high flexibility, force feedback, gravitational equilibrium and so on underthe satisfied workspaces.Secondly, based on the structure, the paper deduces the kinematics and dynamicsmodel of the master manipulator. The forward and inverse kinematics is built by themodified DH method. According to the models, the paper reduces the Jacobian matrixand defines the operability of the master manipulator, by virtue of which the dexterity istested among the workspace. And then, by the method of the lagrange, the dynamics isbuilt after comparing several dynamic modeling methods. And then, the torque for forcefeedback is figured out through the force jacobian matrix, and by combining thedynamics, the torque of the motor is obtained.Finally, the paper designs the motion simulation and function test experiment. The motion simulation is carried out by the virtual prototype of the manipulator in theADAMS. The simulation result is recorded and compared to the theoretical result whichbased on the kinematics and dynamics equation, to verify the accuracy of the kinematicsand dynamics models. Considering the actual motion of the master manipulator, thepaper simplifies the gravitational equilibrium model according to the proportion of thedynamics equation components. At last, the paper carries out the function testexperiment, including the encoder calibration test, accuracy test, gravitationalequilibrium test and force-feedback test, to verify the operating characteristics of themaster device.