Localization, Calibration, Control, and Design of Magnetically Actuated Soft Capsule Endoscopes

Current medical technologies are converging to minimally invasive diagnosis and therapy.The effort to reduce patient discomfort in gastrointestinal (GI) tract diagnoses resulted in thedevelopment of wireless capsule endoscopes (WCEs). In the form of a pill, a camera carryingWCE travels through the GI tract by natural peristalsis while it collects images of the internalwall of the GI tract. The operation might be entirely painless. However, their inability to haveactive locomotion and control limit detailed diagnoses, therapeutic functions, and minimizationof the operation time. Actively controlled WCEs would resolve those challenges.This thesis provides methods for the active control of WCEs using magnetic interactions,and applies those methods to a robotic biopsy capsule endoscope. First, a localization methodfor meso-scale magnetic robots is developed. The method utilizes a magnetic sensor arraywhere a magnetically actuated capsule endoscope (MACE) does not require a special devicefor localization but a single magnet. The method is beneficial to reduce the size and the batteryconsumption of the MACE. The method focuses on decoupling the magnetic field of theMACE from the magnetic field of the actuator, and developing a real-time localization algorithm.Second, an automatic calibration method for magnetic actuation and sensing systemsis presented. The method calibrates a number of nonlinear magnetic sensors and a number ofelectromagnets. The method is capable of calibrating 1.8k parameters in an exemplary systemin a reasonable time without human labor. In this work, Bundle Adjustment framework fromComputer Vision is modified and adapted to magnetic robot sensing and actuation systems.This work would be useful for a magnetic system which requires frequent reconfiguration orsensor/actuator gain updates. Third, control methods for a meso-scale magnetic robots on asurface with non-uniform magnetic field actuations are presented. The control methods utilizemagnetic energy wells to cope with a low actuation bandwidth compared to the fast dynamicsof the capsule endoscope. Additionally, we present a teleoperation system to mitigate the orientationcoordination difficulty when a person uses the system. Fourth, all of the above three methods are integrated and applied to a magnetically actuated soft capsule endoscope for thebiopsy functionality (B-MASCE). We designed a biopsy capsule endoscope with a high diagnosticaccuracy by adopting a clinically well established biopsy method called fine-needlecapillary biopsy. Ex vivo experiments in a fresh porcine stomach show promising results. Insummary, this thesis presents localization, calibration, control methods and their application ina biopsy capsule robot, which are useful for the automation of robotic capsule endoscopes. Weenvision that, in future, patients have painless GI tract endoscopy and treatment with highlyfunctional robotic endoscopic capsules.

当前医学技术正趋向于微创诊断与治疗。为减轻胃肠道（GI）诊断过程中的患者不适，研发了无线胶囊内窥镜（WCEs）。以药丸形态的携带摄像头的WCE通过自然蠕动穿过GI道，同时采集其内壁图像。该操作可能完全无痛。然而，其无法主动移动和控制的特性限制了详细诊断、治疗功能以及手术时间的最小化。主动控制的WCEs将解决这些挑战。本论文提供了利用磁相互作用主动控制WCEs的方法，并将这些方法应用于机器人活检胶囊内窥镜。首先，开发了一种适用于中尺度磁机器人定位的方法。该方法利用磁传感器阵列，磁驱动的胶囊内窥镜（MACE）无需特殊定位设备，仅需要一个磁体即可实现定位，有利于减小MACE的尺寸和电池消耗。该方法专注于解耦MACE的磁场与执行器磁场，并开发实时定位算法。其次，提出了一种用于磁驱动和传感系统的自动校准方法。该方法校准了多个非线性磁传感器和多个电磁铁。该方法能够在合理的时间内校准一个典型系统中的1.8k个参数，无需人工干预。在本工作中，对计算机视觉中的Bundle Adjustment框架进行了修改和适应，以应用于磁机器人传感和驱动系统。这项工作对于需要频繁重新配置或传感器/执行器增益更新的磁系统非常有用。第三，提出了在具有非均匀磁场作用的表面上控制中尺度磁机器人的方法。控制方法利用磁势阱来应对与胶囊内窥镜快速动力学相比的低驱动带宽。此外，我们还提出了一种遥操作系统，以减轻当人员使用该系统时的方向协调困难。第四，将上述三种方法集成并应用于用于活检功能的磁驱动软胶囊内窥镜（B-MASCE）。我们设计了一种通过采用临床已建立的细针穿刺活检方法来提高诊断准确性的活检胶囊内窥镜。在新鲜猪胃的离体实验中显示出有希望的结果。总之，本论文提出了定位、校准、控制方法及其在活检胶囊机器人中的应用，这些方法对于机器人胶囊内窥镜的自动化非常有用。我们展望未来，患者能够经历无痛的GI道内窥镜检查和治疗，并使用高度功能的机器人内窥镜胶囊。