Research On Key Technologies Of Force Sensing Of Surgical Micro-instrument Forceps Based On The Elastomer

Robot assisted minimally invasive surgery is a new type of surgery and the trend of the development of the surgery, which can obtain the effect of open surgery at the expense of the minor trauma. It has some advantages of little trauma, less bleeding, faster recovery, high precision and high success rate. For the surgical robotic system, the force sensing interaction between surgical micro-instruments with the patient’s tissues plays an important role in the operative process. It helps operators perceive the hardness of the surgical site and measure tissue properties, so as to early warning or to avoid additional damage to organs. In this paper,a new single-degree-of-freedom surgical micro-instrument with three-dimensional force sensing is suggested for celiac minimally invasive surgery robot.According to the research status of surgical micro-instruments at home and abroad, the force sensing methods of micro-instruments and the installation positions of the force sensing on the surgical instruments are analyzed in detail. According to the design principle and technical index,a novel elastic body structure is proposed,and the whole structure design of forceps of the micro-instrument is completed based on the elastomer. Then, the kinematic analysis of forceps driven by single push rod is carried out, and the corresponding mathematical models are established.After selection of strain gauges, its layout on the surface of the elastomer is completed.On the basis,a differential full bridge circuit is set up. By applying ANSYS software simulation analysis, the paste position of the strain gauge is selected, and the linearity of the elastomer surface at the position is verified. The static simulation analysis of forceps is carried out by applying the Static Structural of Workbench software, verifying the consistency between the simulation value and the theoretical value,and modal simulation analysis of it is completed with the Modal model, getting the natural frequency and the natural formation of the micro-instrument.Three-dimensional force decoupling of the novel forceps is studied. Firstly, the mathematical model of the single axial force and strain is established. On this basis, a new nonlinear decoupling algorithm is proposed based on the piecewise polynomial fitting of the strain subtraction, and two-dimensional force static decoupling of forceps is realized and verified respectively. A novel three-dimensional force decoupling algorithm of the micro-instrument is proposed on the basic of two-dimensional force decoupling models of two forceps, realizing the direct measurement of grasp and three-dimensional pulling forces of surgical. The validity of the design is theoretically verified in the end.Designing and setting up the static calibration experiment system of the forceps,including the manufacture of a single forcep and the construction of calibration experiment platform. In the meanwhile, designing and producing a signal filter amplifier, then the selection of data acquisition board is completed. Finally,the data acquisition program of the system is written with using the LAB VIEW software, and calibration experiment scheme is presented in detail.