The safety transfer on the sea is threatened by wind, wave and surge loads. An offshore gangway ensures smooth and safe transfer by compensating the ship’s motion. In a mixed offshore gangway system, the transfer gangway is a huge asymmetric load on top of the stable platform, and the displacement of its center of gravity causes it to exert a large dynamic load on the stable platform. A dynamic model of the offshore gangway under dynamic load is established in this work. The Lagrange equation is used to establish the dynamic model of the transfer gangway; the equivalent center of gravity method is used to visualize its dynamic load. The dynamic of the stable platform is modeled by the virtual work principle. Finally, the accuracy of the mathematical model was verified by the joint simulation. Simulation results indicate that under the influence of dynamic load, the tractive force of the second drive support chain is 2–3 times greater than the tractive force of the first and third drive support chains. With the same excitation, the tractive force of the second drive support chain is 2.83 times higher than that under the static load.

Ship cargo-hold cleaning is a low-efficiency and high-risk operation in marine industry, which is generally carried out manually, putting the workers in danger. To improve the efficiency and safety of ship cargo-hold cleaning, a C-DCR is proposed in this article. Most research on the dynamics and control of CDPRs has focused on the scenarios with fixed bases; however, the effect of moving-base excitation on the end-effector is largely ignored. In this article, the dynamic model is established based on Lagrange method considering the ship motion and external disturbance, in which the motor model is considered. On this basis, for the high-speed maneuverability of the C-DCR, a modified PD feedforward tracking controller was proposed. Furthermore, the stability of the controller was proved with the Lyapunov Stability Theory. To keep the cable in tension at all times, the tensions are optimized based on the minimum 2-norm method. The simulation results show that the error mean of position is 0.22 m and the angular error mean is 2.8° under ship motion and external disturbance, indicating that the C-DCR has stable, smooth and bounded tracking performance, which will ensure the accuracy of the cleaning operation.

Due to the marine environment, the operation efficiency of marine cranes is low, and it is easy to cause safety accidents. In this study, magnetorheological (MR) technology is applied to the field of payload anti-swing for marine crane, and designs a parallel MR anti-swing device. The dynamic model of the anti-swing system is derived based on the robot theory and Lagrange method. To enhance the efficiency of anti-swing and reduce the energy, the variable universe fuzzy PID (VUFPID) controller is designed. The anti-swing effect of MR anti-swing device is simulated and analyzed. The results show that the effect of payload anti-swing is exceed 80%, and the energy consumption of MR anti-swing device with VUFPID controller is reduced by 49% compared with MR anti-swing device with a fixed current (1.9 A) under the approximate anti-swing effect. The physical prototype of MR anti-swing device is installed on the laboratory crane. The experimental results show that the attitude of the payload is reduced by 80%. The proposed MR anti-swing device improve the efficiency of Marine cranes.

Constrained by the unique operational conditions and the swinging motion of the payload, offshore cranes exhibit low lifting efficiency and positioning accuracy during operation. In this paper, magnetorheological (MR) technology is applied in the realm of payload anti-swing and positioning of offshore cranes for the first time. The anti-swing system adopts a parallel mechanical configuration design, offering a simple structure that does not encroach upon the crane's working space and exhibits high levels of robustness. Based on the principle of robotics, the kinematic and dynamic model of anti-swing system is derived. Co-simulation analysis is conducted to assess the swing response of the crane's payload throughout the lifting and transfer process amidst irregular ocean waves. The findings demonstrate that the MR anti-swing system effectively mitigates payload swing, achieving an anti-swing effect of over 80%. With a similar anti-swing effect, the MR anti-swing system with time-varying current reduces energy consumption by 54% compared to the system with fixed current. Subsequently, experimental results from the physical prototype reveal that the anti-swing system can suppress payload swing by over 80% during cargo transfer processes. This underscores the capability of the MR anti-swing system to enhance payload transfer efficiency and positioning accuracy.

Ship cleaning poses significant risks and consumes considerable time, primarily due to the irregular hull surface geometry and the unpredictable ship motion induced by wave excitation. To address this challenge and achieve efficient, autonomous cleaning, a spatial variable structure cable-based bulkhead cleaning robot (SC-R) is proposed. Unlike traditional cable-driven parallel mechanisms (CDPMs), SC-R operates in a non-inertial frame, whereby its motion is subject to continuous and unpredictable ship motion. Consequently, SC-R exhibits intricate dynamic characteristics, posing a significant hurdle for controller design. To solve this problem, a sliding-mode controller is proposed for SC-R. Specifically, the dynamic model of SC-R, which includes ship motion and various disturbing forces, is systematically established using the Newton-Euler method. Furthermore, a fuzzy adaptive PI sliding-mode controller (FAPI-SMC) is specifically proposed to enhance the convergence speed and robustness of SC-R. The stability of the closed-loop system is analyzed using Lyapunov theory, and the tracking error is proved to be eventually bounded. Finally, the availability of this theory is confirmed by simulation and experiment. It is shown that FAPI-SMC can achieve a satisfactory control effect in practice.

To address the challenges of low positioning efficiency, difficulty, and high risk in the hoisting and positioning of a slender-beam payload (SBP) under rough sea conditions, a human-machine cooperative lifting method (HMCLM) is proposed for the first time. In this approach, the operator collaborates with a multi-tagline anti-sway and positioning system (MTAPS) to achieve the rapid and precise positioning of the SBP. A dynamic model of the MTAPS is developed based on multibody dynamics and classical Newtonian mechanics; it also considers the operator’s safety requirements. Simulation analysis is conducted using MATLAB/Simulink, and the results indicate that the HMCLM achieves approximately a 10% improvement in sway reduction compared to the MTAPS. Furthermore, the experimental results demonstrate that the MTAPS achieves an average sway reduction of 89.7% for the double-pendulum system. The proposed HMCLM enables the rapid and precise offshore positioning of the SBP, offering a novel approach to enhancing the efficiency of offshore hoisting operations.