An Alignment Method for Magnetically Actuated Flexible Endoscope in Colonoscopy

Magnetically-actuated flexible endoscopes (MAFE) have been well used in minimally-invasive surgery because they can be remotely steered by a magnetic field thus achieving more flexible visual feedback than traditional endoscopes. By controlling the actuator magnet (AM) mounted on a robotic manipulator, MAFE can be steered to align with the target by visual feedback control. However, the non-linearity of the flexible robot and the magnetic field make the control method of MAFE become difficult. Image changes resulting from MAFE rotation are difficult to predict due to the inability to generate a moment of rotation around the MAFE optical axis. In this paper, we established a kinematics model from robot joints to the MAFE and achieved visual feedback alignment control of the endoscope by proposing a control algorithm to control the magnetic field forces and moments. To study the consuming time and accuracy of the alignment of our control method, we investigated the effect of several factors on the alignment through experiments.