Research On Kinematic Modeling Of A Continuum Manipulator For Signle Port Access Laparoscopy Surgery

The operation precision,telepresence,safety,recovery time can be improved via robotic minimally invasive surgery.With development trends of less traumas,high precision,miniaturization and high integration,the innovation design for actuation design,joint and transmission design of surgical robots,which result in difficulty for system design,modeling and optimization of surgical robots.These problems are the focus and difficulty in the research area of medical robots.For the problems of system design and manipulator modeling for single port access laparoscopy surgical robot,this thesis researches the key problems of single port access laparoscopy surgical robot design and manipulator mechanism design,modeling and optimization,combined with the National Natural Science Foundation of China.Base on analysis for environment and operation of single port access laparoscopy surgery(SPALS),a 16 degrees of freedom(DOF)SPALS robot integrated with multi-joint continuum manipulator and micro surgical instrument is development.A multi-joint continuum manipulator as the positioning mechanism is development which can satisfy the constraint environment and the requirement for omitting the leverage effect.In addition,the pulley wheel block mechanism is designed to develop a high miniaturization and integration micro instrument.For addressing the actuation coupling between the continuum manipulator and micro instrument,the decoupling model is established base on a geometric method via analyzing the actuated mode and distribution of the actuated wires.Aiming at the non-constant deformation of our proposed notched continuum manipulator,a mechanics modeling methodology of notched continuum manipulator based on the Timoshenko element is presented.Based on the manipulator deformation characteristic via the ANSYS simulation,the mechanics model of the manipulator is established base on the mechanics models of deformation elements.When the mechanics models of deformation elements are addressed,the coupling between the deformation elements and distribution forces between the manipulator and actuated wires are considered simultaneously.The mapping for manipulator actuated space,joint space and work space can be obtained via the manipulator and deformation elements mechanics model.Moreover,the effectiveness of the mechanics model is experimental validated on continuum manipulators with different notches.In order to solve the kinematics challenge caused by the manipulator redundancy,equivalent rigid-joint assumption based kinematic model is development.The continuum manipulator is equivalent to the rigid joints,in which deformation notches are equivalent to discrete joints.In that manner,the D-H method and curve-fitting method are employed to derive the forward and inverse kinematics.By experimental testing the mechanics-based forward kinematics and the curve-fitting-based inverse kinematics in the manipulator prototype,the kinematics model is validated to map manipulator distal position and manipulator deformation.Furthermore,two kinematic performance evaluation indices are developed to comprehensively describe the performance distribution characteristics in the workspace.Geometric optimization for the notched continuum manipulator is developed base on those performance indices,in which the NSGA-II algorithm is employed to calculate the optimized parameters.The simulation results indicate that the deformation ability and kinematic performance can be improved based on the optimization algorithm.Aiming to hysteresis estimation of the notched wire-actuated manipulator caused by the wire actuated hysteresis and return difference,a non-linear hysteresis modeling approach for the wire-actuated continuum manipulator is presented based on the Bouc-Wen model.Firstly,the static and dynamic experiments are implemented to test the manipulator hysteresis characteristic,in which the hysteresis of the manipulator is affected by the actuated wire pre-load.Then,the hysteresis of the manipulator is modeled based on the Bouc-Wen model,and the parameter identification is also presented.Eventually,the experimental results indicate that our proposed model can simulate the non-linear hysteresis of the wire-actuated continuum manipulator.It can establish the foundation for the real-time control.To validate the functionality and manipulation effectiveness of the SPALS robot,the 16 DOF SPALS robot system and experimental platform are built.The experimental testing results of single joint motion and multi-joint motion of single manipulator,combined motion of multi-manipulator and joint decoupling motion indicate that our proposed SPALS robot can satisfy the requirement for DOF and kinematic performance of the SPALS and guarantee the joints decoupling.In addition,the joints kinematic performance and decoupling ability of the micro instrument are also validated.Finally,the experimental testing for the 16 DOF SPALS robot manipulation performance indicate that the kinematic performance and gripping ability of the 16 DOF SPALS robot are excellent and can meet the SPALS requirements.