Capsule endoscopy is a new type of technology in the diagnosis and treatment of digestive diseases, with painless and low invasive features. However, current capsule robots have many problems, such as over-sized, single function and lack of active locomotion control. This study proposed and designed a new wireless modular capsule robotic system in pipe. The modular capsule robots could move forward and backward in the pipe in the axial direction, turn in a bending environment, and achieve the rendezvous and separation action through the three-dimensional rotating magnetic field generated by the three-axis Helmholtz coils. In this paper, the drive system of the three-axis Helmholtz coils, the power supply control system, and the modular capsule robot structure were analyzed and designed respectively. Finally, a series of characterization experiments were carried out to evaluate the motion characteristics of the modular capsule robots, including the influence of the flow environment imitated to human body's gastrointestinal motility, the frequency of the input signal, and the different structure of the robots on the movement characteristics of the modular capsule robot in this study. The study also evaluated the turning characteristics of robots. Experimental results showed that under different circumstances, modular capsule robots had good motion characteristics, and the effectiveness of the modular functionality had also been verified.
Keywords: Capsule robot; Modular interface; Power supply control system; Three-axis Helmholtz coils.