Towards Tasks Autonomy in Robotic Magnetic Endoscopy

Digestive diseases are numerous and potentially severe. The most common of these are the Inflammatory Bowel Syndrome (IBS) and the Inflammatory Bowel Disease (IBD). Moreover, according to the International Agency for Research on Cancer, cancer is the leading cause of death in the 21st century. Colorectal Cancer (CRC) is the third most common disease worldwide. The CRC starts with a small, benign mass, named polyp which, if identified in its early stages, can be removed with a survival rate of almost 90%. On the other hand, the survival rate drops drastically to less than 10%, when CRC is diagnosed in its later stages. For this reason early prevention is fundamental. Several procedures are employed for examining the Gastrointestinal (GI) tract, such as gastroscopy for the inspection of the esophagus and stomach and colonoscopy for the colon. The colonoscope is a Flexible Endoscope (FE), that allows for visual inspection of the colon, tissue biopsies and polyps removal. However, the aged design of FEs requires lengthy and expensive training for the clinicians which has led to a shortage of gastroenterologists with respect to the high demand. In addition, issues around the invasiveness of FEs, due to the aged design and the method of actuation, cause tissue stretching and, thus, discomfort for the patient. This discourages patients from attending this potentially life-saving procedure. Therefore, despite the widespread adoption of the conventional FEs, the demand for less invasive, innovative procedures has increased. Robotic endoscope solutions claim to overcome the main limitation of conventional FEs. The adoption of robotic endoscopic procedures, which aim to reduce pain and discomfort for the patient, generally lead to a reduction in the need for sedation and recovery time. This results in an increase in the number of patients inclined to undergo endoscopic procedures. In particular, magnetically actuated robots have been investigated in the last two decades with the main advantage of potential miniaturization and minimal invasiveness. The concept of magnetic endoscopy consists of using either coil-based systems, rotating permanent magnet-based systems or permanent magnet-based systems. The permanent magnet-based devices have the advantage of compact size and low energy consumption. On-the-other-hand, the lack of direct control over the intensity of the magnetic field and its gradient leads to reduced controllability of the system. Therefore, the choice of suitable control techniques, relative to the specific task to be performed, is crucial. The work in this thesis makes use of a single permanent magnet attached to the End Effector (EE) of a robotic manipulator. Magnetic forces and torques are used, in this context, to steer and navigate a magnetic endoscope through the GI tract. However, due to the non-intuitive nature of the magnetic fields, the implementation of an intelligent and suitable control approach is necessary. The work in this thesis seeks to overcome this issue.