【作者】 赵德春；

【导师】 彭承琳；

【作者基本信息】 重庆大学 ， 生物医学工程， 2008， 博士

【摘要】 无线胶囊内窥镜检查法使采用内窥镜图像法检查整个小肠成为可能,并且不会让病人感到疼痛以及任何的不适现象,检查非常方便。但目前还存在一些技术瓶颈,如定位和运动机制、合适的能源,使无线内窥镜的应用受到限制。本论文针对能量传输、干扰等技术问题,分析了无线内窥镜的研究现状,归纳比较了国内外无线内窥镜产品或者原型设计,设计了按需式无线内窥镜,并重点对按需式无线内窥镜中的高效低频电磁感应连接、射频通信中的抗干扰技术和天线进行了深入的研究。本论文的主要研究工作和结论如下:1.采用可编程逻辑器件和微控制器协同工作模式,设计了按需式无线内窥镜。该设计已获发明专利授权。按需式无线内窥镜为数字、双向无线内窥镜,其中图像数据采用射频通信传输,以获得高的数据速率;控制指令采用低频电磁感应连接传输,以降低系统的功耗。按需式无线内窥镜中可编程逻辑器件控制图像传感器和射频器件,负责图像数据的采集和发送;微控制器控制低频电磁感应连接,负责接收控制指令、设置相关参数。这样对图像数据的传输处理更加有效、结构更加简洁,同时简化了微控制器的设计,使系统的配置更合理。按需式无线内窥镜增加了胶囊的处理和控制能力,能在体外的控制下即时地、按需地修改相关的参数。2.研究无线内窥镜系统中电磁感应三维接收各线圈输出感应电压的特点,设计了一种新的整流合成电路结构——复合整流合成电路。在电磁感应连接三维接收中,每个方向上电压的波形一致,只存在幅值和初相不同,且初相只有同相和反相的差别,仍采用半波或者全波整流,将影响能量传输的效率和控制数据的接收,采用复合整流合成电路有助于提高系统的灵敏度,克服电磁感应连接方向性的限制,消除通信中的盲点,提高了数据传输的可靠性和能量传输的效率,为无线内窥镜系统体外向体内控制指令的发送和能量传输提供了理想的平台。3.分析与无线内窥镜相同频段不同应用的信道特征,总结无线内窥镜系统干扰源的特点,为跳频系统和固定频率系统设计了一种新的抗干扰方法。这种方法为解决低功耗便携式无线装置的抗干扰问题提供了新的思路。该方法具有以下的优点:通过差错控制和变更射频通信信道,提高了无线内窥镜系统的抗干扰能力,保证了数据可靠传输;通过低频电磁感应发送控制指令,减少了差错处理时间;当发现有丢失或者错误数据包立即发送请求重传指令,减少了内窥镜胶囊发送不必要的数据,降低了系统功耗;变更信道和差错控制都由体外装置处理,不会增加体内装置的复杂度。4.研究了天线设计中的微型化技术,以及影响天线性能的因素,并为无线内窥镜系统设计了微带天线。该天线采用阿基米德螺旋线结构、以及介质基座和短路针技术。它具有以下优点:尺寸小,直径不大于8.3mm;频带宽,在驻波比不大于2时,频率范围为2.3～2.63GHz,中心频率为2.44GHz;天线的发射效率高,最小的回波损耗为-23.7dB;不受周围组织的影响。并且该天线采用双面印制板工艺,一致性好。该天线完全能够集成到无线内窥镜胶囊内。本论文从结构、参数控制、电磁感应连接、抗干扰技术和天线方面对按需式无线内窥镜进行了研究,不仅减少了无线内窥镜胶囊的复杂度,降低了系统功耗,增加了参数控制,而且减少了数据传送的误码率,提高了图像的质量,同时还能够扩展无线能量传输功能,为按需式无线内窥镜的进一步研究和实现奠定了理论和实践基础。更多还原

【Abstract】 Wireless capsule endoscope started the epoch of gastrointestinal inspection. It is possible to inspect the whole small intestine by endoscope image. It is painless and does not make patient feel disconfortable. The inspection is very convenience. However, some tech-necks still exist, such as orientation, moving mechanism and energy sources. These problems limit the application of wireless capsule endoscope. Aiming at the technical problems of energy transmission and anti-interference, this dissertation analyzed the research status of wireless capsule endoscope, concluded and compared wireless endoscope products and prototype designs, and designed the wireless capsule endoscope on-demand. This paper especially paid attention to the reseach of high-efficency and low-frequency electromagnetic induction link, anti-interference technology in radio-frequency communication, and antenna of wireless capsule endoscope. It mainly includes the following distinctive research work and conclusions:1. A wireless capsule endoscope on-demand was designed by adopting the mode of cooperation between programmable logic device and micro control unit. This design has been awarded with invention patent. This capsule is digital and double-direction. In order to get high data rate, it transmits image data with radio-frequency. And it transmits control command with low-frequency electromagnetic induction link to reduce the consumption power. The programmable logic device and the radio-frequency transmitter in wireless capule endoscope are to collect and send image data. And the micro control unit is to receive control command and set relative parameters. It is much more effectively and compactly to transmit the image data with this method. At the same time, it can predigest the design of the control device and make the system scheme more rational. The wireless capsule endoscope added managing and controlling ability. It can modify parameters instantly and on-demand by controlling.2. A new rectifier called the composite rectifier was designed by researching the character of inductive voltage in the three-dimension receiver of the wireless capsule endoscope. The wave of each inductive voltage of the three-dimension receiver is identical. The only difference among the three inductive voltages is magnitude and initial phase. Initial phase only concludes in-phase and out-of-phase. If using the half-wave rectifier and full-wave rectifier for synthesis, it will effect energy transmitting efficency and control data receiving. The composite recitifier is helpful to improve system sensitivity. It can overcome the direction limit of the electromagnetic induction link, eliminate the blind spot and enhance the efficiency of energy transmitting. This design can provide a perfect flat for control command and energy transmitting in wireless capsule endoscope.3. A new anti-interference was designed by analyzing the channel characters of different application in same frequency. This way can provide new research thought for solving the interference of the low-power and portable device in wireless transmitting. It involves many merits as follows: By error controlling and changing channel, it can enhance the anti-interference ability of wireless endoscope system and ensure data communication. By sending control command via low-frequency electromagnetic induction link, it can reduce the time of error processing. Once confirming data packet is lost or wrong, it will send request for retransmitting command, and reduced needless data sending and consumption power. Channel changing and error controlling is dealt with out-body device, and would not add the complexity of in-body device.4. A new antenna was designed for the wireless capsule endoscope by researching the miniature technology and the factors effecting antenna capability. This kind of antenna is composed of the spiral structure of Archimedes, dielectric substrate and shorting pin. It includes merits as little size, broad-band, high efficiency, and not be effected by tissues around it. The diameter of this antenna is not more than 8.3mm. The center frequency is 2.44GHz. When the voltage standing wave ratio is not more than 2, the range of the frequency is 2.3～2.63GHz. The minimum return loss is -23.7dB. This antenna is made by PCB. The consistency of this antenna is great. So the antenna can be completely integrated into the wireless endoscope capsule.This dissertation researched the wireless capsule endoscope in structure, parameter control, electromagnetic induction link, anti-interference and antenna. It not only reduced the complexity of wireless endoscope capsule, decreased consumption power, enhanced parameter control, but also reduced data transmitting error ratio, improved image quality, and enlarged the wireless energy transmitting. It settled the theory and practice foundation for latter research on wireless capsule endoscope.更多还原