SCMAS: an IMU-based 6-DOF closed-loop permanent magnet actuation system for magnet agent

Over the past two decades, the method of controlling magnetic capsule robots for targeted drug delivery in gastrointestinal (GI) environments using external magnetic fields has been frequently discussed. In typical targeted drug delivery tasks, capsule robots must not only possess the ability to navigate across large obstacles but also adjust their orientation upon reaching the target site. However, most reported magnetic actuation systems struggle to simultaneously fulfill these two requirements. In this paper, we present a three-degree-of-freedom (3-DOF) semi-open closed-loop magnetic actuation system (SCMAS) for generating static gradient magnetic fields and dynamic rotating magnetic fields. By utilizing a BLE-IMU module to provide real-time feedback on the orientation of the internal permanent magnet and employing a PD controller for precise control, the SCMAS achieves both high accuracy and adaptability. We applied the SCMAS to a permanent magnet capsule robot and a capsule drug delivery robot, conducting multi-point drug delivery experiments in isolated porcine gastric tissues. The experimental results demonstrate that the SCMAS can achieve localized point-to-point orientation control and speed control over a wide range. This study may provide new insights into control strategies for magnetic capsule robots in the future.