Research On Precise Positioning System Of Wireless Capsule Endoscope And Chip Design

The wireless capsule endoscope is a major breakthrough in gastrointestinal disease examination technology.It is the most representative application of the human body local area network in the field of biomedicine.Compared with the traditional cable gastroscopy,the WCE detection technology has the advantages of no cross infection,no pain,and easy swallowing.For the positioning system of WCE,RF positioning technology is one of the hotspots in its research.Among them,the positioning accuracy of the TOA algorithm is optimal,but its time delay error will affect the positioning accuracy of WCE.Some researchers mix the TOA algorithm with other positioning technologies in order to improve the accuracy of WCE,but they still cannot eliminate the time delay error.In the indoor RF positioning technology,the positioning algorithm of TDOA algorithm can eliminate the arrival time delay error.However,in the process of solving the equations,there is a problem of fuzzy solutions,which is not suitable for WCE positioning.In response to the above problems,this paper conducts research from the following aspects:(1)Propose ΔTOA positioning algorithm: Take advantage of the short sampling period of WCE,this paper approximates its motion trajectory in the body to a uniform linear motion.In the two adjacent states,the WCE position difference with time delay error is equal to the WCE position difference with time delay error removed,so as to achieve the purpose of eliminating time delay error and improving positioning accuracy.According to the simulation results: under the same error,the positioning accuracy of the proposed algorithm is better than that of the TOA algorithm.(2)Design the low-noise amplifier circuit of the ultra-wideband receiver of WCE:Because the positioning system of WCE is closely related to energy monitoring,an incoherent receiver is used in the positioning system of WCE.This paper proposes a LNA for a non-coherent receiver,and uses a cascode structure with source negative feedback inductance.In order to meet the required ultra-wideband performance indicators,RC negative feedback structure is used to increase its bandwidth.Finally,through the passive Balun structure to achieve single-ended input full differential output conversion.The simulation results show that the low-noise amplifiers designed in this paper can meet the design specifications.