A Study on Simultaneous Magnetic Actuation and Localization based Robotic Navigation System for Active Wireless Capsule Endoscopy

WCE is a popular alternative to conventional endoscopy for the examination of the gastrointestinal tract due to its non-invasiveness and ease to use. However, the passive locomotion of current WCE has limited its use. SMAL is a promising technology that can endow the capsule with the capability of active locomotion and accurate localization, which has the potential to reduce the inspection time and improve the diagnostic accuracy.This thesis addresses several challenges associated with active WCE by proposing advanced SMAL systems and techniques for automatic navigation of a robotic capsule, aiming at performing efficient and safe propulsion, trajectory following and real-time localization based on the magnetic fields.First, we develop the IF-SMAL system based on a rotating magnetic actuation and an external sensor array to achieve closed-loop SMAL for a magnetic capsule. An integral filter based approach is proposed to eliminate the undesired magnetic field interferences between the actuation and localization modules, combined with an automatic state detection method and a multi-model localization algorithm to improve the localization performance. Then, in order to improve the localization update frequency, an advanced version of the system, the IMOT-SMAL system, is proposed by integrating a novel algorithm for capsule localization. To overcome the challenges of propelling the capsule through a complex-shaped tubular environment, we further investigate the capsule locomotion in a sharp bend, and develop the IMOT-ASMAL system with enlarged workspace and enhanced locomotion capability in sharp bends by adopting an automatically activated optimal sensor sub-array and online actuator adjustment. Compared with the previous work, the system achieves the state-of-the-art performance in terms of propulsion efficiency, workspace and localization update frequency and comparable localization accuracy.In order to improve patient safety during the examination, in particular to prevent the capsule from causing damage to the intestinal tissues, a theoretical analysis of the impact of a rotating capsule on the intestinal walls under different magnetic actuation modes are conducted, and a novel magnetic actuation method named RRMA is proposed to replace the commonly used CRMA method. Based on this new actuation approach, several trajectory following strategies are studied and demonstrated in a tubular environment.Finally, inspired by the procedures of routine colonoscopy and concepts in mobile robot navigation, we propose the first autonomous magnetic navigation framework for active WCE in an unknown tubular environment, which consists of two steps--the AP step and the TF step, to imitate an experienced physician performing the ""insertion"" and ""withdrawal"" procedures in conventional colonoscopy. During AP, the capsule is automatically propelled through the entire intestine under the supervision of a physician and a smooth trajectory is generated. This step mimics the ""insertion"" step in routine colonoscopy, which is crucial to explore the unknown tubular environment and provide a viable path for subsequent inspections. Then, during TF, the capsule will traverse the generated trajectory while receiving positioning instructions of a physician, which mimics the ""withdrawal"" step in conventional colonoscopy to facilitate accurate and repeated inspection of suspicious lesions. The feasibility of the navigation framework is preliminarily validated in the experiments on phantoms and ex-vivo animal organs.無線膠囊內窺鏡由於其無創性和易用性，是一種受歡迎的替代傳統內鏡的消化道檢查手段。然而，被動的運動方式限製了現有無線膠囊內窺鏡的使用。同時磁驅動與定位(SMAL)是一種很有前景的技術，它可以賦予膠囊主動運動和準確定位的能力，具有缩短檢查時間、提高診斷準確性的潛力。本論文通過提出用於機器人膠囊自主導航的先進同時磁驅動與定位系統和技術，解決了與主動型無線膠囊內窺鏡相關的幾個挑戰，目標是基於磁場實現安全高效的推進、軌跡追蹤和實時定位。首先，我們開發了基於積分濾波的同時驅動與定位系統(IF-SMAL)，基於旋轉磁驅動和外部傳感器陣列實現磁膠囊的閉環同時驅動與定位。提出了一種基於積分濾波的方法來消除驅動和定位模塊之間的磁場幹擾，結合自動狀態檢測理論和多模型定位算法來提高定位性能。然後，為了提高定位更新頻率，該系統的改進版本--基於改進型多目標追蹤的同時磁驅動與定位系統（IMOT-SMAL）被提出，其集成了一種用於膠囊定位的新算法。為了克服在復雜形狀的管狀環境中推動膠囊的挑戰，我們進一步研究了膠囊在急彎中的運動，並提出了基於改進型多目標追蹤的自適應同時驅動與定位系統（IMOT-ASMAL）。通過采用最佳傳感器子陣列的自動激活技術和驅動器位姿在線調整技術，該系統擁有增大的工作空間和在急彎中增強的運動能力。與先前的工作相比，該系統實現了最先進的推進效率、工作空間和定位更新頻率以及相當的定位精度。為提高患者在檢查過程中的安全性，特別是防止膠囊對腸組織造成損傷，我們對不同磁驅動方式下旋轉膠囊對腸壁的影響進行了理論分析，提出了一種名為往復旋轉磁驅動（RRMA）的新型磁驅動方法來代替常用的連續旋轉磁驅動（CRMA）方法。基於這種新的驅動方法，研究並驗證了在管狀環境中的多種軌跡跟蹤策略。最後，受常規結腸鏡檢查流程和移動機器人導航概念的啟發，我們首次提出了用於未知管狀環境中的主動型無線膠囊內窺鏡的自主磁導航框架，它包括兩個步驟--自主推進（AP）步驟和軌跡追蹤（TF）步驟，來模仿有經驗的醫生在常規結腸鏡檢查中執行"進鏡"和"退鏡"操作。在自主推進期間，膠囊在醫生的監督下被自動推進穿過整個腸道，並生成平滑的軌跡。此步驟模仿常規結腸鏡檢查中的"進鏡"步驟，這對於探索未知的管狀環境並為後續檢查提供可行路徑至關重要。然後，在軌跡追蹤期間，膠囊將在接收醫生的指位指令的同時在生成的軌跡上運動，以方便對可疑病變進行準確和重復檢查。此步驟模仿常規結腸鏡檢查中的"退鏡"步驟。導航框架的可行性在仿體和離體動物器官的實驗中得到了初步驗證。XU, Yangxin.Ph.D. Chinese University of Hong Kong 2021.Includes bibliographical references (leaves )Abstracts in English and Chinese.Title from PDF title page (viewed on ...