Multimodal conversion of a magnetic navigated dual-hemisphere capsule robot based on self-standing characteristics

Capsules applied in large-volume and unstructured organs, such as stomach and colon, should perform multimodal motion to effectively accomplish gastrointestinal tract diagnosis. For this purpose, a magnetic navigated dual-hemisphere capsule robot (DHCR) actuated by the spatial universal rotating magnetic field (SURMF) is proposed, utilizing its passive and active modes for fixed-point posture adjustment and rolling locomotion, respectively. The DHCR exhibits a distinctive physical property—self-standing characteristics, which can specify vertically upward orientation as the starting posture and benchmark for multimodal motion after the DHCR undergoes complex multimodal (pseudo-active, active, and passive modes) conversion. On the basis of the momentum moment theorem, a general dynamic model is devised to reveal the mechanism of multimodal transition through stability and posture response. Results show that the DHCR can flip spontaneously after applying SURMF and is finally in a stable passive mode with the vertically upward DHCR axis. Finally, the multimodal conversion of the DHCR is tested in turning navigation within the curved intestine, providing a new method of endoscopic diagnosis.