The Flexible Pressure Sensing System For End Force Sensing Of Minimally Invasive Surgical Robot

With the rapid development of medical technology,robot-assisted minimally invasive surgery(RMIS)has attracted much attention because of its unique advantages of less trauma,less pain and faster recovery.The current lack of accurate force sensing system at the end of minimally invasive surgery is prone to cause accidental injuries during minimally invasive surgery,which brings hidden dangers and challenges to surgical safety.Therefore,the development of a new minimally invasive surgical robot end force sensing system is important to further improve the safety of RMIS and promote its further promotion in the clinic.However,the current problems of poor flexibility compatibility and incompatibility between high sensitivity and wide detection range of three-dimensional force sensors limit their application in end force sensing for RMIS.In view of the urgent demand for force sensing system at the end of RMIS,and to address the current key problems of force sensing at the end of minimally invasive surgery,this thesis proposes the preparation of a RMIS end pressure sensing system based on a high-performance flexible three-dimensional force capacitive sensor using an integrated design of orthogonal trigonal microstructured dielectric layer and microstructured electrode.The system is capable of detecting the three-dimensional force of the minimally invasive surgical end-effector in real time when clamping or touching the tissue,and visualizing the three-dimensional force information on the PC.The research work in this thesis provides technical support for the design of the end force sensing system for RMIS.The main research of this thesis is as follows.(1)Design of the flexible pressure sensing system for end force sensing in RMIS.Firstly,the structural design and material selection of the flexible three-dimensional force capacitive sensor,which is the core of the pressure sensing system,are carried out.The microstructured dielectric layer of the sensor is also modeled in three dimensions,and the feasibility is verified using the finite element simulation.Secondly,the detection principle of the sensor is described,and a model for solving and deriving the three-dimensional force is established.Finally,the test scheme of the flexible pressure sensing system is designed,including the design of signal measurement circuit and acquisition system,and the test platform for detecting and calibrating the sensor is built.(2)Preparation and performance study of the sensor for end force sensing in RMIS.The effects of different spacing of microstructured dielectric layer on the performance of the unit sensor are analyzed,and a high-performance flexible three-dimensional force capacitive sensor is prepared by combining screen printing and magnetron sputtering.The results show that the sensor has a wide detection range(0-3N)and high sensitivity(69.19%/N)in the normal force direction,and also shows excellent flexibility,dynamic stability,low hysteresis,interference resistance and consistency.The sensor is also tested and calibrated for three-dimensional force response.And the mathematical model between experimental data and fitting function is established,which can calculate the magnitude of the acting three-dimensional force in real time,laying the foundation for the application of the sensor in RMIS.(3)Construction and experimentation of the test system for the flexible pressure sensing system in RMIS.A test platform for integrating and testing the flexible pressure sensing system is built,and the flexible pressure system is integrated into the RMIS clamp and touch bar to perform actions such as clamping and touching on bionic tissues.The research results show that the flexible pressure sensing system is able to upload the information of the magnitude and direction of the three-dimensional force of the tissues detected by the end-clamp and the touch bar to the PC in real time,and realize the realtime detection and visual display of the three-dimensional force.In addition,the system is able to form a preliminary force feedback to the end-clamp force,forming a closed system of force sensing and feedback,which provides a new idea for the research of end force sensing and feedback in RMIS.