A Novel System for Closed-Loop Simultaneous Magnetic Actuation and Localization of WCE Based on External Sensors and Rotating Actuation

• Published in: IEEE transactions on automation science and engineering 2021-10, Vol.18 (4), p.1640-1652
• Main Authors: Xu, Yangxin, Li, Keyu, Zhao, Ziqi, Meng, Max Q.-H.
• Format: Article
• Language: English
• Subjects: Accuracy; Actuation; Actuators; Algorithms; Diagnosis; Endoscopes; Feasibility; Human motion; Interference; Intestine; Localization; Magnetic actuation and localization; Magnetic fields; Magnetic resonance imaging; Magnetic sensors; Magnetic separation; medical robotics; Power consumption; robotic system and software; Robustness; Rotation; Sensor arrays; Sensor systems; Systems design; wireless capsule endoscopy (WCE)
• ISSN: 1545-5955; 1558-3783
• DOI: 10.1109/TASE.2020.3013954

Simultaneous magnetic actuation and localization (SMAL) is a promising technology for accelerating and positioning the capsule in the human intestine for wireless capsule endoscopy (WCE). In this article, we propose a novel system that uses a rotating magnetic actuator and an external sensor array to achieve closed-loop SMAL for a capsule with two embedded magnetic rings. First, the state of the capsule is detected as "Stuck," "Synchronous," or "Missing" by studying the relationship between the theoretical actuating magnetic field and the measured total magnetic field. Then, the undesired interference with the localization system caused by the actuator is eliminated with an integral filter-based approach. Different models are proposed to solve the pose of the capsule according to the different states of the capsule, and the localization result is used to update the pose of the actuator to close the loop. Extensive experiments on phantoms and animal organs with different environmental conditions are carried out to validate the proposed framework. The state detection accuracy achieves 96.7%, and the capsule can be located with an accuracy of 5.5 mm and 5.2° in position and orientation, respectively. Experimental results show the feasibility of our proposed system and demonstrate the robustness, accuracy, actuation efficiency, and closed-loop performance of the system. Note to Practitioners -The motivation of this article is to solve the problem of controlling the movement of a wireless capsule endoscope in the human intestine to assist intestinal diagnosis and treatment. We present a feasible system design and corresponding algorithms to achieve closed-loop simultaneous actuation and localization of a robotic capsule. The design of a simple structure placed inside the capsule (i.e., two magnetic rings) and an external sensor array mounted on the examination bed can reduce the size and power consumption of the capsule, and the use of a rotating actuator helps improve the actuation efficiency. The proposed SMAL framework, which is composed of state detection, interference removal, multimodel localization, and actuator updating, can close the actuation-localization loop and improve the accuracy and robustness of the system. We demonstrate the superiority of the proposed framework compared with others through extensive experiments. In the future, our SMAL system can be combined with image- or ultrasound-based automatic diagnosis and is expected to provide doctor