Design And Experimental Research Of Diagnosis And Treatment In-strument For Gastrointestinal Endoscopic Robot

Gastric cancer has become one of the most common cancers that endanger human life and health in today’s society,and early detection and diagnosis of gastric diseases can improve the survival rate of patients^[1].Combined with minimally invasive surgical techniques,endoscopic submucosal dissection（ESD）has become the mainstream.The existing endoscope platform has a large structure and generally only has one or two working channels.Due to the narrow and long surgical channel,the surgical operation space is limited,and there are problems such as operation blind spots and difficulty in precise operation.Combined with the latest research progress of Natural Orifice Transluminal Endoscopic Surgery（NOTES）,this paper develops a multi-degree-of-freedom flexible continuum diagnosis and treatment device to solve the above problems.The developed flexible diagnosis and treatment instrument will be inserted through the forceps channel of the gastrointestinal endoscope robot platform（or the forceps channel of commercial gastrointestinal endoscope）,and the diagnosis and treatment operations will be performed at the end of the robot platform.In this paper,a flexible continuum medical instrument based on Nitinol material is proposed.The medical instrument has a compact structure（the maximum outer diameter is only 3 mm,the full length is 1237 mm）,light weight and high dexterity.The medical instrument is designed as an independently driven double bending part,in which 60°bending motion can be achieved by the degree of freedom of expansion,and135°bending motion can be achieved by the combination of the double bending part in one direction.The flexible continuum diagnosis and treatment instrument has 5 degrees of freedom（deployment,pitch,yaw,linear motion,and surgical forceps opening and closing）,forming a surgical operation triangle area,expanding the surgical operation space,and facilitating doctors to perform complex surgical operations.At the same time,the end of the diagnosis and treatment instrument can be equipped with different execution devices to meet the needs of diagnosis and treatment,such as surgical forceps,electric knife,confocal microscopic imaging probe,laser ablation optical fiber,etc.In addition,in order to save costs,a multi-lumen tube that meets the strength requirements is selected for the passive bending part of the medical instrument,and a driving device with a tensioning structure is designed according to the principle of compact structure.Secondly,taking surgical forceps as an example,the static model simulation analysis is carried out to verify its reliability.The maximum strain of the flexible hinge is predicted by the elliptical shape assumption,and its accuracy is verified by finite element analysis.At the same time,the driving force and deflection of the flexible continuum diagnosis and treatment robot are calculated based on Castigliano’s first theorem and the static model of the material constitutive relationship.The relationship between the bending angle and the kinematic model of the flexible continuum diagnosis and treatment robot was established based on statistical methods to calculate the relationship between the displacement of the driving wire and its bending deflection angle.Finally,the construction of the flexible continuum diagnosis and treatment robot system is completed.The kinematics accuracy measurement experiment shows that the kinematic error of the flexible continuum diagnosis and treatment robot is 1.3673mm,and the relative error is 2.1453%;Experiments have verified its basic flexibility,which can achieve 135°bending deflection;the scanning area of the flexible continuum diagnosis and treatment robot can reach 12 mm² through scanning imaging experiments,which meets the requirements of optical biopsy;through in vitro animal tissue cutting and laser ablation experiments,it is verified that Feasibility of flexible continuum diagnosis and treatment robot for surgery.The experimental results show that the flexible continuum diagnosis and treatment robot for the gastrointestinal tract designed in this paper can realize a wide range of surgical operations,which can solve the problem of blind spots for doctors during the operation and reduce the difficulty of complex surgical operations.