Zengkai Liu

The electronic control system assumes a crucial role in the management, regulation, and safeguarding of equipment within subsea production systems. To ensure the normal operation of the system and improve the reliability of the electronic control system, hardware redundancy is often employed. External shocks can accelerate the state transition of components, and the state changes of electronic control system components may affect other redundant components. Therefore, this paper proposes a multi-state competing failure reliability assessment method based on the correlation of redundant components. By analyzing the degradation and sudden failure processes of electronic control system components, a system state transition probability matrix based on Markov processes is constructed to delineate component state categorization and evolution. The hierarchical model is combined with dynamic Bayesian networks to quantify the impact of system redundancy component correlation on model parameters using a set of hyperparameters. Building upon this analysis, a hierarchical dynamic Bayesian network grounded in competing failure process is established. The probability of each component being in different states after undergoing a competing failure process is analyzed. After considering the influence of redundant component correlation, the overall system reliability deteriorates more rapidly. Finally, the system state evolution under different maintenance strategies is analyzed.

With the increasing demand for ocean resource exploitation, deep-sea exploration, and environmental protection, the importance of underwater operation technologies has become more prominent. Traditional rigid robotic arms lack flexibility in complex underwater environments, limiting their effectiveness in diverse tasks. Flexible robotic arms, with their pliable structures, offer superior adaptability. However, the influence of geometric design on the performance of water-driven actuators remains unclear, hindering their optimization. This study systematically investigates a three-degree-of-freedom water-powered soft actuator, analyzing how chamber geometry affects its bending performance and load capacity. Through static analysis, finite element simulations, and experimental validation, the effects of chamber shapes (sector, semicircular, and circular), lengths, and cross-sectional areas on actuator performance are evaluated. Results indicate that sector chambers provide optimal bending and load capacity, while semicircular and circular chambers offer comparable precision and adaptability. Optimizing chamber length and cross-sectional area is critical for enhancing performance in complex environments. Furthermore, the inclusion of a stretch limiting layer and the design of water supply channels passing through the actuator significantly improve stability and load-bearing capacity. This study provides theoretical guidance for designing underwater soft actuators, supporting applications such as shipwreck salvage, artifact retrieval, and biological sample collection.

Seafloor landing research is crucial for underwater robots tasked with long-term fixed-point observation missions, particularly those requiring prolonged operations on the seabed. Developing safe and stable landing technology is essential for the success of these missions. This paper introduces a novel underwater robot by establishing its dynamic model and using the arbitrary Lagrangian–Eulerian (ALE) method to conduct a comprehensive study of its deep-sea landing process. Prior to detailed parameter analysis, the ALE algorithm’s effectiveness and accuracy were validated through experimental data and simulation results from previous studies. This study examines the penetration depth and force conditions during the landing process by varying factors such as seabed soil properties, landing velocity, and the robot’s mass. Findings indicate that seabed soil properties significantly influence penetration depth and pressure, with variations in soil density and strength affecting the robot’s landing behavior. In contrast, the robot’s mass has a relatively minor effect, suggesting that the choice of structural materials has limited impact on penetration depth and pressure during landing. Additionally, landing velocity was found to significantly affect penetration depth and pressure; higher velocities result in greater penetration depths and pressures. This highlights the importance of controlling landing velocity to minimize impact forces and protect the robot. The results of this study provide theoretical support and data for developing deep-sea landing technology for novel underwater robots and inform the selection of structural materials, ensuring the successful execution of long-term fixed-point observation missions in deep-sea environments.