Development of a new hull adsorptive underwater climbing robot using the Bernoulli negative pressure effect

Climbing on a vertical ship hull underwater while using surface cleaning tools remains a great challenge for climbing robots. In this study, we design a negative-pressure adsorptive underwater climbing robot using the Bernoulli negative-pressure generation mechanism. Computational fluid dynamics modelling is performed with a sliding mesh to explore the optimal adhesion performance. The factors that influence the adsorptive force are investigated, such as the contra-rotating propellers (CRPs) speed and gap distance between the bottom plate of the robot and the adsorbate, and their cause and effect are established by taking into consideration the fluid pressures and velocities for the Bernoulli negative-pressure effect on the bottom plate of the robot. Based on the optimal parameters determined from the numerical simulations, a prototype adsorptive climbing robot is fabricated and tested in a water pool. Comparisons with the experimental results show that the numerical model predicts the adsorptive force with an accuracy of 94.1%. The proposed method and the findings reported in this paper are valuable in guiding the design of negative-pressure adsorptive parameters for climbing robots, and will significantly improve the robot's capability to precisely adjust the adsorptive force by driving the CRP motor accordingly. •Designed an underwater robot by Bernoulli's theorem to generate adsorptive force.•Robot adapts to various adsorbates, with contactless, large and controllable force.•Factors that affect the optimal adsorptive force were studied.•The sliding mesh method was performed to reveal the formation process of the force.•A numerical model to estimate the force was validated with the experimental data.