Research On Reliability Of Surgical Instrument Of Minimally Invasive Surgery Robot

Robot-assisted minimally invasive surgery is an important milestone in the development of surgical surgery.With the help of surgical robots,doctors can perform more precise surgical operations in a more comfortable environment,with less trauma caused by surgery and faster recovery of patients.As the direct execution unit of the surgeon’s operation in the robot-assisted minimally invasive surgery,surgical instruments with the ability to achieve multiple degrees of freedom of motion simulating the human arm make the operation more flexible.During surgery,surgical instruments need to be inserted into the human body and directly contact with internal organs and tissues,so that a higher requirement of safety and reliability should be guaranteed.Therefore,based on the surgical instruments of the "Mcro Hand" surgical robot system independently developed by Tianjin University,the reliability of surgical instruments was analyzed and studied by using reliability engineering theory and method.The specific research contents are as follows:First of all,the adverse event reports of Endo Wrist instruments of Da Vinci surgical robot system are statistically analyzed,and some common failure modes of instruments are identified.Combined with two common fault analysis methods of failure mode effects and criticality analysis(FMECA)and fault tree analysis(FTA)in reliability engineering,it is determined that the wire-driven system is the weak link and key unit in surgical instruments.Then,the fatigue test of wire rope(the key part of wire-driven system)was carried out in a self-made fatigue test platform.The characteristics of the fatigue life of wire rope under different working conditions were studied and analyzed by using statistical analysis theory and method,and the life distribution model of wire rope were determined.On this basis,the related reliability parameters of wire rope were calculated,and the P-S-N curves(the relation curve between stress S and life N under different survival rates P)were drawn.According to the P-S-N curve,the safety life with a certain survival rate of wire rope working under a certain stress level can be predicted.Combined with tensile test and microscopic surface damage analysis,the mechanical property decline law and surface damage evolution law of wire rope were studied and analyzed,and finally the failure mechanism of wire rope was determined.Finally,according to the actual size and structure layout of wire-driven structure,the reliability test platform for different kinematic degrees of freedom of wire-driven structure was made,and the reliability verification test of wire-driven system was conducted.Then the motion accuracy of end-effector was analyzed,and the reliability of wire-driven system was verified to meet the requirements.According to the test results,some measures to improve the reliability of surgical instruments are put forward.