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复合诊断胶囊内窥镜关键技术研究
其他题名Research on Key Technologies of Capsule Endoscope with Composite Diagnosis
邵琪1,2
导师李洪谊 ; 刘浩
分类号TP242
关键词复合诊断胶囊内窥镜 胶囊机器人 微型ph传感器 无线能量传输系统 E类功率放大电路
索取号TP242/S34/2015
页数115页
学位专业模式识别与智能系统
学位名称博士
2015-11-25
学位授予单位中国科学院沈阳自动化研究所
学位授予地点沈阳
作者部门机器人学研究室
摘要胶囊内窥镜作为一种新型的消化道疾病检测手段,具有无痛、无创、无交叉感染、使用方便等优点,已广泛应用于临床。然而,现有的胶囊内窥镜产品仍存在一些缺陷,阻碍了该技术的临床价值与未来发展。第一,检测功能较为单一,仅能采集到消化道内的一种信息,即形态学信息或生理参数信息,导致许多消化道疾病的阳性诊断率偏低。第二,供电系统都是采用电能和输出功率均受限的纽扣电池,导致胶囊内窥镜的工作时间偏低,可能无法覆盖整个消化道。第三,图像传感器的帧率和分辨率以及生理参数传感器的采样率和精度都偏低,可能会造成一些病灶的遗漏,从而影响到它的临床效果。 为了解决上述问题,本文将设计一套集成复合诊断技术和无线供能技术的新型胶囊内窥镜。其中,前者可实现形态学信息和生理参数信息的同步采集,为消化道疾病的鉴别诊断提供多维信息,有效提高疾病的阳性诊断率。而后者利用了发射线圈与接收线圈之间的电磁耦合,可向体内的胶囊内窥镜传输连续、足量的电能,保证各功能模块的能量供给。 对于复合诊断技术,本文将在现有光学胶囊内窥镜的基础上,集成微型的生理传感器。考虑到pH值是临床常用的生理参数,将作为本文的研究对象。根据尺寸、性能、成本等约束条件,pH传感器将采用锑电极作为工作电极,Ag/AgCl电极作为参比电极。随后,搭建实验平台,对该传感器的线性度、准确性、响应时间、温度漂移等特性进行测试。结果显示,这些特性都可满足临床需求。 对于无线供能技术,本文将分别从该系统的设计、建模、优化及补偿控制等方面进行研究。首先,从总体上,先确定了发射线圈与接收线圈的谐振方式和拓扑结构。由于胶囊内窥镜的负载属于低电压、大电流的类型,更适合采用双串联谐振的方式。为了保证无线供能的位置稳定性和姿态稳定性,将采用单维发射线圈与三维接收线圈的拓扑结构。在此基础上,建立起该系统的效率模型,其总效率包括发射效率、耦合效率和接收效率。 其次,研究了发射端的建模与补偿策略。E类功率放大电路作为发射端的重要组成部分,具有电路简单、效率高、成本低等优势。目前,该电路的设计参数都是基于标称模型来确定。但是,由于该模型没有考虑MOSFET的开关时间及导通损耗,故不适合直接用于本系统。针对这一问题,本文将分别在考虑和不考虑开关时间的前提下,建立两套电路模型。结果显示,开关时间会影响电路波形,但基本不影响电路特性。同时,导通损耗会影响到电路效率,且次标称状态下的电路效率最高。随后,建立了次标称状态下的电路模型。在此基础上,确定了不同占空比下的最优电路参数,对应效率远高于标称状态下的效率,从而实现了发射端的参数优化。此外,发射电路的特性可能会受负载阻抗偏移的影响,使其偏离次标称状态。针对这一问题,本文设计了三套补偿系统,分别是电抗、占空比与频率补偿系统。通过对这三套系统的对比分析,发现频率补偿系统在便携性、使用范围和稳定性上具有明显优势,更适用于发射端的阻抗补偿。 最后,研究了接收端的建模与优化。接收端的设计参数主要包括接收线圈的层数、匝数和线径以及接收电路的结构。根据尺寸和频率等约束条件,本文将先建立接收线圈的阻抗模型,研究线圈参数与阻抗特性的之间关系。而接收电路由整流电路和稳压电路组成,包括两套可选方案。通过对两套方案的输入输出关系进行分析,分别建立相应的电路模型。根据这两套模型,可建立接收端的效率模型,推导出设计参数与总效率的关系,从而实现接收端的参数优化。 综上所述,本文对胶囊内窥镜的复合诊断技术和无线供能技术进行了深入的研究。其中,前者通过集成微型的图像传感器和生理参数传感器,实现消化道内多维信息的同步采集,提高了消化道疾病的阳性诊断率。而后者通过建立完整的效率模型,对发射端、接收端的设计参数进行优化和补偿控制,提高系统的效率和稳定性。通过对这两项关键技术的集成,可有效解决胶囊内窥镜在临床应用中面临的问题,推动了胶囊内窥镜的进一步发展与应用。
其他摘要As a novel diagnostic tool for the gastro-intestinal(GI) diseases, capsule endoscope (CE) has the advantages of no pain, no invasion, no cross infection and convenience and it has been widely applied in clinic. However, the present CE products still have several drawbacks, which restrict the clinical value and future development of this technology. Firstly, their detection functions are very simple, since they can just capture one kind of information, i.e. morphological or physiological information, which results in a low positive diagnosis rate of many GI diseases. Secondly, they all adopt button battery with the limited capacity and output power as their powering system, which results in a low operating time and may not cover the whole GI tract. Thirdly, the frame rate and resolution of the image sensor and the sampling rate and accuracy of the physiological sensor are normally low, which leads to the omission of some lesions and influences its clinical effect. To solve these problems, this paper proposes a novel CE integrated with composite diagnosis and wireless powering transfer (WPT) technologies. The former can realize a synchronous acquisition of morphological information and physiological information to provide multi-dimensional information for the diagnosis of the GI diseases, which can greatly improve their positive diagnosis rate. The latter can utilize the electromagnetic (EM) coupling between the transmitting and receiving coils to transfer the adequate and continuous power to the CE inside the body, which can ensure the power supply for all the functional modules. For the composite diagnosis technology, this paper integrates a micro physiological sensor on the basis of the existing image CE. Since pH is a common physiological parameter, we employ it as the study object in this paper. Based on the constraints of size, characteristics and cost, pH sensor adopts the antimony electrode as the working one and Ag/AgCl electrode as the reference one. Then, an experimental platform was built up to measure the linearity, accuracy, response time and temperature shift of this sensor. The results show that they all match the clinical needs. For the WPT technology, this paper performs the study from the aspects of the system design, modeling, optimization, compensation control, etc. At first, as a whole, we determine the resonant type and topology structure of the transmitting and receiving coils. Because the load of a CE belongs to the type of low voltage and high current, the double-serial-resonant type is more suitable. Moreover, in order to ensure the position and orientation stability of the WPT system, we adopts the topology of one-dimensional transmitting coil and three-dimensional receiving coil. Then, the efficiency model of the system is built up and the overall efficiency consists of the transmitting efficiency, coupling efficiency and receiving efficiency. Besides, the model and compensation strategy of the transmitting unit is studied. As a vital part of the transmitting unit, class-E power amplifier (PA) has the advantages of simple circuit, high efficiency, low cost, etc. Recently, the design parameters of the PA are always determined by the nominal model. However, this circuit model does not take switching time and conduction loss of MOSFET into consideration, so it is not suitable to be directly applied to the system. To solve this problem, this paper builds up two circuit models with and without considering switching time of MOSFET respectively. It is concluded that switching time would affect the circuit waveform, but its influence on the circuit performance is negligible. Meanwhile, conduction loss of MOSFET would affect the efficiency of the PA and the efficiency reaches its peak at the subnominal condition. Then, the circuit model of the PA at the subnominal condition is built up. Subsequently, the optimal circuit parameters for different duty ratios are derived, which has a much higher efficiency than that at the nominal condition and realizes the parameter optimization of the transmitting unit. Furthermore, the characteristics of the PA may be affected by the variation of the load impedance, which causes its operating condition shifts from the subnominal condition. For this problem, this paper proposes three systems, including the reactance, duty ratio and frequency compensation systems. With the comparison and analysis of these systems, it is concluded that the frequency compensation system has more advantages in portability, applicable range and stability, so it is more suitable for the impedance compensation of the transmitting unit. Finally, the model and parameter optimization of the receiving unit is studied. The design parameters of the receiving unit mainly consist of the layer number, turn number and wire diameter of the receiving coil and the structure of the receiving circuit. Based on the constraints of size and frequency, this paper firstly builds up the impedance of the receiving coil to study the relationship between its design parameters and impedance. The receiving circuit is composed of the rectifier and regulator, which has two available schemes. With the analysis of the input and output of two schemes, their circuit models are derived. According to these two models, the efficiency model of the receiving unit is built up to study the relationship between the design parameters and overall efficiency, which can realize the parameter optimization of the receiving unit. In general, this paper carries out a thorough study of composite diagnosis and WPT technologies of CE. For the former, a synchronous acquisition of multi-dimensional information of GI tract is realized by integrating micro image sensor and physiological sensor, which can improve the positive diagnosis rate of the GI diseases. For the latter, the total efficiency model of the system is built up to realize the parameter optimization and compensation control of the transmitting unit and receiving unit, which can improve its efficiency and stability. With the integration of two technologies, the clinical problems of CE can be solved effectively, which greatly promotes its further development and application.
语种中文
产权排序1
文献类型学位论文
条目标识符http://ir.sia.cn/handle/173321/17532
专题机器人学研究室
作者单位1.中国科学院沈阳自动化研究所
2.中国科学院大学
推荐引用方式
GB/T 7714
邵琪. 复合诊断胶囊内窥镜关键技术研究[D]. 沈阳. 中国科学院沈阳自动化研究所,2015.
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