Research On Micro-bionic Robot For Intestinal Diagnosis And Its Wireless Power Transfer System

As one of the alternatives to the insertion gastrointestinal endoscope,the micro-bionic robot for intestinal diagnosis system has broad application prospects and important research value.This article is supported by the National Natural Science Foundation Project(No.81971767),Shanghai Scientific Research Project(No.19441910600,No.19441913800,No.19142203800),Shanghai Minhang District Industry-University-Research Cooperation Project(No.2019MHC053),Medical Robot Research Institute Project of Shanghai Jiao Tong University(No.IMR2018KY05),design and integrate the miniature bionic intestinal robot diagnosis system,and conduct in-depth research and optimization for its key technologies such as wireless power transfer,so as to provide theoretical guidance and technical basis for the establishment of new minimally invasive or non-invasive diagnosis and examination methods for intestinal diseases.Intestinal robot motion system: Based on the non-structural physiological environment of the human intestine and its non-linear biomechanical characteristics,the resident force model of the intestinal robot expanding in the intestine is established,and on this basis,a miniature bionic intestinal robot motion system adapted to the biological structural characteristics of the human intestine is designed and studied.It adopts an inchworm-like driving method,and performs two-way movement through expansion and contraction.Design a new double-layer staggered arc anchoring mechanism with a large variable diameter ratio of up to 3.3 to achieve effective residence in the intestine.In order to make the robot more compact,the axial movement mechanism adopts the design of a micro-motor reducer and a screw nut mechanism.Many measures have been taken to save the volume of the mechanism.The diameter of the whole designed movement mechanism is 13 mm,the overall length of the mechanism is 29.3 mm when fully contracted,and it can reach 40.3 mm when fully extended.Principle analysis of wireless power transfer system and module construction: According to the principle of electromagnetic induction,the human environment and the actual movement of the robot in the intestine,a dedicated wireless power transfer system suitable for intestinal robots is studied.And analyze the design requirements of the wireless power supply module in the power required by the intestinal robot diagnosis system,the stability of the wireless power transfer,and the electromagnetic field safety of the human biological.Based on the reflected load theory,an equivalent circuit model of the wireless power transfer system is established.And according to the energy requirements of the robot work,the transmitting and receiving coils and circuits of the wireless power transfer system is designed and completed.Optimization design of the wireless power transfer system at the transmitting end: A parallel opposed wireless power transfer system is proposed,and the magnetic core is embedded in the transmitting coil for the first time in the system.The intensity of the magnetic field generated by the coil is derived through mathematical theory,and the distribution of the magnetic field is simulated.And through experiments,the influence of the magnetic core on the wireless power transfer system of the parallel opposed transmitting coil is studied,and the received power and power transfer efficiency at various points in the system are analyzed.After adding the magnetic core,the maximum power transfer efficiency of the system reaches8.68%,and the overall power transfer stability of the system is above 90%,and the highest can reach 94.24%.While without the magnetic core,the minimum power transfer stability is only 83.06%.The transmitting coil of the system adopts an up-and-down structure,and the distance between the coils can be adjusted according to the patient’s body type,further improving the power transfer efficiency and stability of the system.A U-shaped transmitting coil wireless power transfer system with a simpler structure is proposed.The experimental and simulation results show that the maximum power transfer efficiency of the system after adding the magnetic core is 14.13%,while the received power is 3780.75 m W,the average power transfer efficiency of the system is 4.16%,and the average received power is 1337.24 m W.In general,parallel opposed transmitting coils wireless power transfer system have better power transfer stability,and the intestinal robot can work stably in a larger range,so that a larger intestinal range can be detected in a single diagnosis.Optimization design of the wireless power transfer system at the receiving end: based on the principle of the three-coil wireless power transfer system,the load coil turns are optimized to improve the power transfer efficiency and received power of the three-coil wireless power transfer system for the intestinal robot.And a Helmholtz-like load coil three-coil wireless power transfer system is proposed to further optimize the power transfer efficiency and received power.Experiments verify that the proposed Helmholtz-like load coil three-coil wireless power transfer system improves power transfer efficiency and received power.The experimental results show that the performance of the Helmholtz-like load coil 60-turn three-coil wireless power transfer system is better than that of the 60-turn conventional three-coil or twocoil wireless power transfer system.A three-coil wireless power transfer system with Helmholtz-like load coil can achieve the best power transfer efficiency of 6.45%,which is 21.02% higher than a 60-turn two-coil wireless power transfer system,while achieving a received power of 844.9 m W.Robot system integration and prototype performance test: the diameter of the robot prototype is 15 mm(the diameter of the motion system is 13 mm),the length is 45 mm(including the power transfer module and video image module),and the total weight is 20.84 g.Develop the communication,control,and video image modules of the intestinal robot diagnosis system,as well as the circuit and program design integration,to realize the two-way wireless communication and real-time control of the intestinal robot,and the collection of high-definition intestine images.Experiment and analyze the motion performance of the intestinal robot prototype,and test the performance of each module of the intestinal robot prototype in a wireless power transfer environment.The results show that the various modules of the intestinal robot meet the requirements of working in a magnetic field environment in wireless power transfer.This paper analyzes and studies the system integration design,optimization,and experimental verification,provides a better innovative solution for the development of the intestinal miniature bionic robot diagnosis system,and makes positive contributions to its further clinical application.