Study On Structure Design And Properties Based On Shape Memory Materials Of NOTES Robots

Robot-assisted minimally invasive surgery has become an indispensable part of the surgery,and natural orifice transluminal endoscopic surgery is the surgical development trend,which highly requires the miniaturization of surgical instruments.There are very few robotic surgery systems that can adapt to the complex and narrow environment of bending pipes in the human body.Due to the development of intelligent materials and bionic structures,surgical robots tend to be more miniaturized,multi-functional,and have high safety.Based on smart materials like shape memory alloy,this thesis studies the robotic surgery system through a natural cavity.Specific work contents include:（1）According to the physical properties of shape memory alloy material,the structure design,control,and drive of the robot are carried out.The stiffness of surgical robots has always been a very important problem.In this thesis,a kind of continuum robot with variable stiffness,submillimeter size,simple structure,and suitable for complex pipeline structure is proposed.Using infrared control to change the stiffness of the robot,it can switch the robot’s working mode:1.Low stiffness,compliant,the passive compliant moving mode that can be noninvasive in the natural cavity.For example,the curvature of a robot can be predefined using compliance to achieve movement in a complex curved pipe.2.Operation mode with high stiffness,injectable,and precision operation.The robot with submillimeter size combines a shape memory alloy（SMA）and electrospun structure of the low melting point polymer.The robot is controlled by infrared wirelessly and safely.The robot’s surface is coated with polydopamine nanoparticles to improve the infrared response-ability,and the result shows that the photothermal performance of the robot is significantly improved after the coating.In this thesis,SMA’s essential function is achieving variable stiffness of the robot system because of the property of SMA.Transporting and releasing drugs are the main functions of the electrospun structure.To expand the workspace of the robot,Fe₃O₄magnetic particles are doped into the electrospun structure of the low melting point polymer.Finally,we verify the main functions of the robot system through in vivo experiments.（2）Two systems are designed to control the robot’s motion.The first is the motor system with a clamping switch to adjust the clamping position of the robot.In addition to driving the robot to complete linear motion and rotary motion,the characteristics of the system are that the rotary motor is equipped with a clamping switch that can adjust the clamping position.Considering the overall performance of the whole robot system,In order to further realize the integration of the robot with imaging module and infrared control module,a soft robot drive system based on continuum structure is proposed.A machine arm with a wire-controlled continuum structure was designed,and the parameters of the continuum structure were optimized by the finite element method.The structure uses a flexible hollow casing as the backbone,leaving room for carrying miniature or small surgical instruments.In this thesis,the laser fiber is integrated into a hollow casing,and the optical fiber is used as the imaging device,which greatly reduces the size of the system.The system has the advantages of small size,simple structure,and a high degree of integration,and can well adapt to the narrow space with complex bending.The performance of the system is tested,and the integration and driving performance of the system are good.