Safety Analysis and Simulation Validation of Hose Whipping Phenomenon in Air Refueling

This paper aims to identify the main cause of the hose whipping phenomenon (HWP) in air refueling, and come up with effective preventive measures. The system-theoretic accident model and process (STAMP), i.e., the system-theoretic process analysis (STPA), was adopted to evaluate the safety of air refueling. Then, the evaluation results were verified with a self-designed simulation validation model. The results show that the HWP is controlled by the docking speed, reel mechanism, and designed hose length; the swing range and tension change of the hose increased under inappropriate speed control; reel control could end the hazardous state of the hose within 50s after docking; the HWP occurred after the hose length was shortened from 22m to 14m. The research findings provide a reference for the prevention of the HWP.

A simple and reliable reel mechanism-based robotic colonoscope for high mobility

Colonoscopes are one The first two authors contributed equally to this work of the best tools to detect colorectal cancer despite their several drawbacks. In order to solve the limitations of conventional colonoscopes and detect cancer more efficiently, robotic colonoscopes and capsule endoscopes have been proposed. However, active capsule endoscopes require expensive control systems, and they have functional limitations due to their small volumes. In addition, robotic colonoscopes fail to achieve sufficient mobility, resulting in longer colonoscopy times than with conventional colonoscopes. Therefore, the present study proposes a simple, reliable reel mechanism-based robotic colonoscope that achieves high mobility. Because the robot is operated by a reel with an external high-capacity motor, enhanced mobility is attained regardless of environment. Moreover, the proposed robotic colonoscope allows for the inclusion of an instrument channel, unlike previously reported robotic colonoscopes. A theoretical analysis is implemented to confirm the mobile performance. The analysis results are compared with the results of a locomotion test in a urethane tube (diameter = 28 mm). Ultimately, the robot achieves high mobility (66.04 ± 5.97 mm/s with a motor speed of 200 r/min), and the error between the theoretical and experimental results is less than 1%. Furthermore, an in-vitro test in an excised porcine colon is performed to verify the feasibility of the locomotion in a large intestine. In straight and sloping paths (30° and 45°), the robot travels at 21.11 ± 1.69 mm/s, 18.77 ± 3.42 mm/s, and 8.76 ± 1.68 mm/s, respectively, with a motor speed of 150 r/min. This is within the reliable operation range for colonoscopies.