Design And Optimization Of Minimally Invasive Surgery Forceps

The emergence and development of minimally invasive surgical(MIS)robots make the open surgery less bleeding,small trauma,few complications and quick recovery after operation,and the MIS has being accepted and adopted by more and more doctors and patients.The existing MIS forceps,such as the traditional rigid surgical forceps,the flexible MIS forceps and the multifunctional MIS forceps,have the disadvantages of large friction,low mechanical efficiency,complicated assembly process of components and large deformation.In order to solve these problems,we design origami-inspired MIS forceps with bi-stable performance and flexible hinge in this thesis.The main work of this thesis is as follows:First of all,in order to improve the mechanical benefits of surgical forceps and to obtain integrated MIS forceps with flexible hinges,according to the theory of thick panel origami,a kind of surgical forceps mechanism driven by single degree of freedom is proposed and the model is designed.However,the surgical forceps with thick panel origami patterns are difficult to manufacture because they have large number hinges and complex structure,and their diameter is difficult to meet the requirements of MIS forceps.At the same time,due to the possibility of achieving a bi-stable performance of the monolithic folding structure using curved creases,it is considered to introduce this structure into the MIS forcepsSecondly,based on the principle of bi-stable structure,it is proved to be feasible to design a bi-stable structure with developable surface.By means of laser cutting,the curved creases on the plane PET material are designed,and the plane PET material is plastically deformed by using the high temperature heating method to generate the curved surface structure.In order to find out the condition of increasing the number of curved creases bending resistance,the PET material is tested under different heating temperature and heating time,the proper heating time is 12 minutes,the heating temperature is 110 ?,and in this case its mechanical properties is tested.Finally,a series of parametric simulations of the thickness and elastic modulus of the curved structure at the hinge are carried out to find the thickness and elastic modulus of the hinge that matched the experimental results.On this basis,the bi-stable performance of each parameter is simulated by numerical analysis with the purpose of optimizing the bi-stable performance,including the thickness,cross-beam structure,hole structure,plane angle,curvature and width.According to the influence of each parameters on bi-stable performance,the surface structure,the path of the MIS forceps drive wire and the stent structure are re-optimized,and the integrated surgical forceps with bi-stable performance and flexible hinges are accomplished,and its bi-stable performance is verified.To compare the mechanical benefits of conventional surgical forceps with bi-stable surgical forceps,we design a miniature bi-stable surgical forceps with a maximum outer diameter of 15 mm.The experimental results show that the mechanical benefits are 40.9% greater than the traditional surgical forceps.