Research On Kinematic Modeling And Force Perception Of Continuous Manipulator For Single Port Laparoscopy Surgery

Compared with traditional minimally invasive surgery(MIS),single-port surgery(SPS)can decrease the number of incisions,and reduce the injury to patients.The development of a reliable single-port laparoscopic surgical robot(SPSLR)can avoid chopstick effect,provide complex operation,and thus improve successful rate.In addition,the minimally invasive surgical robot(MISR)on the market at present lacks force perception,which makes limitations for surgeon to judge the interaction force during operation,therefore,increases the surgical risk.SPS puts forward new requirements for its robot such as structural design and system integration,and also force perception is a key technology to improve the sensation during surgery.Aiming at the above hotspots,a continuous manipulator facing SPSLR was designed and an experimental prototype was constructed,and also kinematics model,parameters optimization and force sensing are discussed in this paper.First of all,based on the analysis of SPS operation requirements,an intracavitary continuous manipulator for SPSLR was designed,including multi-degree-of-freedom forceps,notched flexible rod,and rigid unfolding joint.The proposed continuous manipulator has small size,light weight,compact structure,and flexible operation.The combination of rigid and flexible mechanism makes the system have high positioning accuracy,kinematic dexterity,and use security at the same time.Secondly,considering the total motion of the notched flexible rod is the accumulation of every flexible ring,whose mechanics and kinematics is coupled.Mechanics model of single flexible ring was established based on the theory of cantilever beam.In the next step,the notched flexible rod was abstracted as a multi-joint series robot,and then forward and inverse kinematics model was built by using D-H parameter method and back propagation neural network(BPNN)algorithm,respectively.On the basis of the above research,key dimensions were optimized using genetic algorithm(GA),improving the motion performance of the notched flexible rod.Thirdly,aiming at the lack of force perception for MISR,the intrinsic force sensing ability of the notched flexible rod was investigated.Utilizing the inverse kinematics model,equal curvature bending model of the notched flexible rod was established.Then,virtual work model of the notched flexible rod was proposed based on the virtual displacement and the Jacobi matrix.Force sensing model was constructed using the least squares theory and contact condition constrain in the next step.An forcing sensing experimental platform was constructed,and the effectiveness of the model was verified experimentally.Finally,modular design was adopted to realize the integration of the experimental prototype.In this part,the hardware platform and the control platform were designed,respectively,and motion control of the system was realized by VB programming.In order to judge the performance of the proposed continuous manipulator,the micro forceps,the notched flexible rod,and the rigid unfolding joints were valued separately,and then external force disturbance experiments and in vitro simulated operation experiment were conducted.The results show that the designed continuous manipulator achieves design goals and has good performance,and thus can be used in further research.