## 8 Conclusions  
In this paper, a new ROV system and its thrust allocation optimization method are proposed for the detection requirements of marine engineering facilities. The main points of the research can be summarized as follows:  
* System design: The ROV's body with an electromagnetic adsorption chassis, a buoyancy mechanism, and an installation framework is constructed, and the portable ground control box and the control system, including the upper computer software and the lower computer program, are developed to realize the efficient coordination of the upper computer and the lower computer.
* Thrust allocation optimization: Based on the vector layout of the ROV's thruster, the thrust-torque mathematical model is established, and the optimization problem is designed to solve the ROV's thrust allocation as the goal and the thruster's saturation as the constraint. Through MATLAB and Unity 3D simulation, the simulation results of the direct logic method and sequential quadratic programming (SQP) are compared, which shows the advantages of the SQP algorithm in solving the thrust allocation problem.
* Experimental verification: The underwater experimental platform is built to complete the motion control experiment. The experiment verifies the accuracy of the simulation results and proves the engineering application feasibility of the SQP optimization method. The simulation scene observation experiment shows that the system can stably complete the underwater inspection task and meet the expected design requirements.
* Future research will focus on the following three aspects: first, lightweight improvement of the electromagnetic adsorption chassis to reduce the complexity of thrust distribution; second, optimizing the layout of the propulsion system and developing a more robust adaptive allocation algorithm; and thirdly, carrying out a field test in the marine environment to verify the reliability of the system under complex working conditions, especially the dynamic response performance under strong current disturbance and multi-obstacle scenarios.  
Conceptualization, F.R. and X.G.; methodology, X.G.; software, B.W.; validation, F.R., X.D. and B.W.; formal analysis, X.D.; investigation, X.G.; resources, F.R.; data curation, Z.W.; writing--original draft preparation, X.G.; writing--review and editing, F.R.; visualization, X.G.; supervision, F.R.; project administration, F.R.; funding acquisition, F.R. All authors have read and agreed to the published version of the manuscript.  
1. CNOOC's major projects, ZX2024 ZCCYF1598: development of an intelligent device management system for pile leg cleaning and testing operations of self-installed production platforms; Hainan Provincial Key R&D Program. 2. Hainan Provincial Key R&D Project, ZDYF2023 CXJS004.  
Figure 26: Steel pipe defect detection image.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data are unavailable due to privacy or ethical restrictions.  
**Conflicts of Interest:** The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. [PERSON] is employee of CNOOC. The authors declare that this study received funding from CNOOC. The funder had no role in the design of the study; in the collection, analysis, or interpretation of data, in the writing of the manuscript, or in the decision to publish the results.