  In recent years, simultaneous magnetic actuation and localization (SMAL) for
active wireless capsule endoscopy (WCE) has been intensively studied to improve
the efficiency and accuracy of the examination. In this paper, we propose an
autonomous magnetic navigation framework for active WCE that mimics the
"insertion" and "withdrawal" procedures performed by an expert physician in
conventional colonoscopy, thereby enabling efficient and accurate navigation of
a robotic capsule endoscope in the intestine with minimal user effort. First,
the capsule is automatically propelled through the unknown intestinal
environment and generate a viable path to represent the environment. Then, the
capsule is autonomously navigated towards any point selected on the intestinal
trajectory to allow accurate and repeated inspections of suspicious lesions.
Moreover, we implement the navigation framework on a robotic system
incorporated with advanced SMAL algorithms, and validate it in the navigation
in various tubular environments using phantoms and an ex-vivo pig colon. Our
results demonstrate that the proposed autonomous navigation framework can
effectively navigate the capsule in unknown, complex tubular environments with
a satisfactory accuracy, repeatability and efficiency compared with manual
operation.
