Research On Tactile Perception Mechanism Of Convex Indenter For Minimally Invasive Surgery

Minimally invasive surgery has been accepted by more and more people because of its advantages of small incision,small wound and quick recovery after operation.However,in minimally invasive surgery,because of lacking the feedback of tactile information when operating medical devices,surgeons are prone to exert too much force that damages human tissue,and sometimes even cause serious medical accidents.Based on the background of catheter minimally invasive surgery,a kind of convex tactile sensor for minimally invasive surgery is designed in this paper.The design of the tactile sensor has a common feature of the planar convex type.Sensitive elements are placed on the convex surface to detect the contact width of the tactile sensor.Meanwhile,the force sensor is used to measure its force on the tissue,and then the elastic modulus of the tissue is estimated,depending on the contact width and the force.Firstly,in order to solve the contact problem between tactile sensors and tissues,a contact model is established based on the Eshelby-Stroh formula,and the boundary value problem is solved according to displacement conditions and stress conditions.Then the whole displacement constraint method,linear superposition principle and iterative method are used to solve the problem correctly.Secondly,using the existing elastic half space solution and Abaqus simulation as comparison object,the accuracy of the tactile perception mechanism is verified,and the adaptability of the algorithm is analyzed.The analysis results show that the optimized algorithm is suitable for orthotropic and isotropic materials,elastic half space and bounded elastic body,cylinder indenter,wedge indenter and rounded wedge indenter.Thirdly,the influence of various parameters on the calculating results is studied,and the appropriate parameters are chosen for the design of sensor contact model.And the design method of convex tactile sensor is put forward.Finally,7 tactile sensor indenters were processed,and 3 kinds of silica gel with different elastic moduli were tested.The validity of the tactile perception mechanism and effectiveness of the tactile sensor are confirmed by comparing the test results with the calibration results of silica gel.