In context
By mid-2023, remotely operated vehicles (ROVs) were increasingly used in deep-sea resource development, salvage, and nuclear inspection. Hybrid electric-hydraulic propulsion was emerging to combine electric efficiency with hydraulic fast response, but existing thrust allocation methods—mostly pseudo-inverse or optimization-based—could not handle the distinct characteristics of two propulsion types.
What was reported
Researchers from the China Ship Scientific Research Center and Wuhan University of Technology proposed a multi-level thrust allocation strategy based on fuzzy logic for a hybrid-propulsion ROV. The system uses four X-arranged electric thrusters (VT1–VT4) and two hydraulic thrusters (VT5–VT6) aligned with the longitudinal axis. The method first distributes the expected longitudinal force increment via a three-dimensional Mamdani fuzzy controller, considering the increment, current electric thrust, and current hydraulic thrust. Then it allocates the desired longitudinal force between the two systems, accounting for their thrust capabilities, and finally performs individual thrust allocation for each thruster.
Simulation comparisons showed that the strategy dynamically adjusts the longitudinal force split based on thrust demand and system states, achieving good motion performance and high operational efficiency. The authors state that the proposed method is more flexible and effective than the pseudo-inverse method, which often ignores physical constraints and can cause saturation.
Why it mattered
This work addressed a gap in hybrid propulsion control, offering a practical way to leverage both electric efficiency and hydraulic responsiveness. The fuzzy-logic approach avoids precise mathematical modeling and can adapt to complex operational demands, potentially improving ROV endurance and maneuverability in industrial underwater tasks.
“The allocation proportion of the expected longitudinal force can be adjusted dynamically according to requirements of thrust and states of the propulsion systems.”
Source: 《机器人》期刊 (robot.sia.cn) · Published 2023-07-08 · “基于模糊逻辑的混合推进ROV多级推力分配策略”