Research And Design Of The Stiffness Controllable Instrument Platform Based On Natural Orifice Transluminal Endoscopic Surgery

As an advanced paradigm in the field of minimally invasive surgery(MIS),natural orifice transluminal endoscopic surgery(NOTES)not only has the same therapeutic effect as traditional laparoscopic surgery,but also has many other advantages such as less pain,short hospitalization,and the most importance is no scar.Due to the various peritoneal access,compared with single port surgery(SPS),NOTES has a wider range of application.Nowadays,as the hot topic in the field of MIS,researches about the NOTES system have made remarkable progress.However,most of the existing systems can not achieve both sufficient flexible workspace and high load capacity.Aiming to meet the medical requirements in NOTES,based on the low melting point alloy gallium,this paper explains the mechanism design,material choosing,actuator design and kinematic and workspace analysis of stiffness controllable instrument platform for NOTES.The main content of this paper is shown as following:Firstly,according to requirements of NOTES,a stiffness controllable instrument platform for NOTES is designed.Mechanism design,material choosing,energy exchange system,actuator design and soft skeleton design are introduced and described in detail.The design improves the flexibility and workspace of NOTES instruments,realizes the efficient rigidity change and guarantees the rigid support for instruments and accuracy of operations.Secondly,based on constant-curvature assumption and modified DenavitHartenberg method,using a kind of simple but accurate geometric method,the kinematic model of stiffness controllable backbone module is established by analyzing the relationship among the actuation space,virtual joint space and workspace.Based on the kinematic model and workspace analysis of single backbone module,kinematic model and workspace of stiffness controllable instrument platform for NOTES which contains two backbone modules are analyzed.Finally,based on the mechanism design and kinematics analysis of stiffness controllable instrument for NOTES,the rigidity characteristic,efficiency of rigid change,workspace and motion error are investigated by experiments.The experiment results show that the designed instrument has good rigidity characteristic and high motion accuracy,in addition,it can achieve efficient rigid change,which can meet the requirements of NOTES.