| Aiming at the defects of the current method for detecting gastrointestinal motility, the thesis, supported by the National Natural Science Foundation of China (NO. 60875061), the National 863 program of China (NO. 2006AA04Z368 and NO. 2007AA04Z234), and the Combination of Medicine and Engineering (Science) Foundation of Shanghai Jiaotong University, studied the interventional telemetric method of the human gastrointestinal physiological parameters and localization technique of telemetric capsule. A portable localization system for localizing the telemetric capsule with high localization accuracy and strong anti-jamming ability was developed.For detecting gastrointestinal motility diseases, an interventional telemetric system was developed, for monitoring the physiological parameters (pressure, temperature and pH value) of the whole gastrointestinal tract under the normal physiological state of human. The whole scheme of the system, the circuits, the program of the MCU, and the data-processing software, were analyzed. By clinical experiments on human, the feasibility of the interventional telemetric system was verified.To solve the problem localizing the telemetric capsule in vitro, the 2D localization method based on region segmentation and RF signal strength, was proposed. The method segmented the region of the abdomen of human. By simulation, the calibration database of"district number and received RF signal strength"was built. Then, by the look-up-table method, the telemetric capsule was localized on 2D districts. So the method solve problem that the attenuation model of RF signal in human body cannot be built accurately because of the complicated characteristics of RF signal attenuation and the difference of the different people. And the anti-jamming ability of the localization method based on received signal strength, was improved. Besides, the localizationg method based on phase difference of received RF signal, the localization method based on permanent magnetic markers, and the localization method based on pulsed DC electromagnetic field, were studied. And by experiments in vitro, the advantages and disadvantages of the methods were compared. And a conclusion can be drawn that the methods outlined above were unfeasible for localizing the telemetric capsule.Based on the analysis of the advantages and disadvantages of the above method, a method for localizing the telemetric capsule based on low-frequency AC electromagnetic field was put forward. In the method, several excitation coils were placed on the abdomen of people, and an induction coil was encapsulated in the telemetric capsule. When localizing the telemetric capsule, the excitation coils were excited with alternating current alternately. And meanwhile, the induction coil detected the electromagnetic field strength produced by each excitation coil, and transmitted the measurement results to the data receiver in vitro to store. Finally, the stored measurement results were uploaded to the software of localization algorithm, and then the position of the telemetric capsule can be acquired. To build the accurate localization model, analyze the magnetic field distribution model of an excitation coil, including the magnetic dipole model, the circle current model, the simplified circle current model, and the current solenoid model based on discretization of field source. By comparing the computation accuracy of the magnetic field strength with the models, the current solenoid model based on discretization of field source, was found more accurate. And with the model, the AC excitation localization model was built. To solve the nonlinear equations deduced from the localization model, the hybrid algorithm, based on the surface response model and simulated annealing algorithm, was proposed; and proved that compute fast and accurately.A portable localization system based on AC excitation was developed. The system was analyzed from the design of system structure, subsystem for detecting magnetic field, subsystem for excitation control and data receiving, and optimization method of system parameters. The multi-information fusion localization method based on D-S theory decision-making, was put forward; and its feasibility was verified by simulation.A test-bed for localization experiments was build. From the results of localization experiments with the portable AC excitation localization system, the localization accuracy was evaluated. To calibration the localization results, the methods of error correction were studied, including the conventional method, high order polynomial fit method, Hardy's Multi-Quadrick method. So the calibration method based on RBF neural network was proposed, and proved that the method can minimize the maximum localization error and mean error.The electromagnetic interaction of the AC excitation localization system with the human tissue was studied, which included the possible electromagnetic radiation of the localization system and influence of the localization accuracy by human tissue. Two experiments were designed to verify the influence of the localization accuracy by human tissue, in which pork and physiological saline were used to simulate the human tissue. On the other hand, by electromagnetic simulation, the electromagnetic radiation dosages of the localization system to human were acquired. By comparing them with the international electromagnetic safety standard for huma, a conclusion was drawn that the localization system cannot cause electromagnetic hazards to human.From the results of experiments and simulation, the AC excitation localization method can satisfy the requirements for localizing the telemetric capsule in vitro. And the portable localization system based on the method, were verified that it achieved high localization accuracy, strong anti-jamming capacity, and no electromagnetic radiation hazard to human. Thus, the localization system developed in the thesis has great clinical practical value.
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