Research On A Haptic Manipulator For Robot-assisted Laparoscopic Surgery

In recent years, with the continuous development of robot-assisted laparoscopic surgical techniques, it has been increasingly prominent in the medical field and has gained widespread concern in society. The master manipulator is the important section of the robot-assisted laparoscopic surgical system. As the main part of the remote control system in the human-computer interaction, the recognition accuracy of the position and orientation, operational flexibility and force feedback performance directly affect the quality of the surgery. Therefore, the research on master manipulator has great significance for surgical robot, even the field of teleoperation technology.According to the requirement of robot-assisted laparoscopic surgery on the master hand, determine the series-parallel master-slave heterogeneous configuration approach to achieve the decoupling of the position and orientation. The design of the7degrees of freedom configuration and4degrees of freedom force feedback method are completed. Depending on difference of the functionality, the master hand is divided into parallel, series and clamping mechanisms. The specific design of each part has been completed. Kinematics is the theoretical basis of the position and posture recognition. Based on space vector equation, the forward and inverse kinematics relationship of the parallel mechanism is derived and the forward kinematics has been performed according to the D-H notation.Jacobi matrix is the basis of dexterity analysis and statics analysis. The Jacobi matrix is established according to kinematic equations derivation and vector product method. The parallel mechanism’s structural size is optimized with the dexterity index and the needs of the working space as the criteria. The singularity of the serial redundant mechanism is analyzed, improving the system’s operational performance. Based on the above optimized mechanism, the stiffness of the main hand has been analyzed.Based on the kinematics and Lagrangian equations, the gravity compensation models of parallel and serial mechanism are established, which establish the corresponding relationship between the position, orientation and joints’ driving torque of the master hand for realizing master manipulator’s self-balancing, and the models are simulated by ADAMS. Based on the principle of virtual work, the statics equations between the output torque and the driving torque of the parallel mechanism are established as the theoretical basis for the force feedback algorithm design.Finally, four experiments including initiative homing, gravity compensation, position and orientation recognition and force feedback have been done to verify that the master manipulator can achieve active homing, position-attitude self-balancing with a high position-orientation detection accuracy and fairish force feedback effects. The redundant mechanism can significantly improve the dexterity of the master manipulator. The gravity compensation model not only help to achieve the master manipulator’s self-balancing to facilitate the operation of doctors, but also to provide theoretical basis for the subsequent establishment of the master manipulator’s accurate kinetic compensation model.