In the second part, after performing in-vitro experiments to measure the resistant force of the small intestine, we propose a magnetic actuation method. The magnetic marker for localization acts as a seed to be actuated by multiple coils placed outside of the human body. The basic idea is that the magnetic seed is subject to a force and a torque in a magnetic field. An efficient computation scheme is designed and implemented to calculate the coil currents for real-time actuation. Simulations are performed on a six-coil actuation system to evaluate the method. As an alternative method, an internal actuator, which consists of a magnetic spring and can propel itself forward under an alternating current, is introduced to increase the mobility of the capsule and decrease the demand for a strong external field. The external magnetic field is also simulated to orient the internal actuator. / The development of wireless capsule endoscope realizes the examination of the whole gastrointestinal tract. The technology reduces patients' pain and benefits the doctors as well. However, it loses some functions that conventional endoscope owns because of the passive locomotion mode. To improve the situation, an active capsule endoscope is preferred by the community. / We put emphasis on two important problems in design of an active capsule endoscope: localization and actuation. The first part of our work focuses on the study of localization of the capsule taking advantage of the magnetic field. A small permanent magnet is enclosed in the capsule as a marker, and a tracking method is proposed based on the modelling of the marker as an ideal dipole. The five localization parameters are computed by minimizing the differences between the theoretical field values and sensing signals using Levenberg-Marquardt algorithm. One-axis Hall sensors and three-axis magnetoresistive sensors are employed respectively to implement the localization method. The system performance is evaluated by a series of tracking experiments. / Wang Xiaona. / "September 2006." / Adviser: Max Meng. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1771. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 155-171). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.