## 5 Conclusions  
We have introduced a comprehensive technical framework to address the lack of systematic operational standards for seabed topography surveys employing AUVs equipped with side-scan sonar systems. This framework has been designed to account for numerous variables while integrating the specific characteristics of the AUV's vertical motion control modes. The experimental results demonstrated the effectiveness of the established approach, ensuring the safety of the submersible and the quality and efficiency of operations in AUV-mounted side-scan sonar surveys. The present study offers two main contributions:  
Figure 34: Both ends of adjacent strips exhibit an elliptical shape.  
Figure 35: Significant stretching in the image when the AUV travels at a speed of less than 1 kt.  
1. We established a technical framework for AUV-based side-scan sonar operations. This research considered a wide range of factors, encompassing vehicle safety, equipment performance, operational efficiency, motion control modes of the vehicle, and data quality. Furthermore, the proposed methodology systematically optimizes the procedural framework for conducting underwater surveys using AUV-based side-scan sonar. Therefore, it can serve as a timeless reference for future research in this field.
2. We conducted an in-depth analysis to study the properties of image data produced through AUV-based side-scan sonar operations. As such, we successfully identified ten distinct attributes that characterize experimental results acquired through ship-towed side-scan sonar surveys. This research provides the foundation for future work to improve the post-processing of data retrieved from AUV-based side-scan sonar operations.  
Based on the findings, the survey line planning method proposed in this article is different from existing AUV path planning research and is more suitable for AUVs equipped with side-scan sonar to conduct underwater terrain detection operations. Additionally, the operational approach proposed in this article holds tremendous engineering significance and can provide a reliable guideline for AUV-based side-scan sonar operations.  
Conceptualization, X.Z. and S.J.; methodology, X.Z. and Y.C.; validation, S.J. and G.B.; formal analysis, X.Z. and G.B.; investigation, X.Z.; resources, G.B. and J.W.; data curation, X.Z. and G.B.; writing--original draft preparation, X.Z.; writing--review and editing, S.J. and C.J.; visualization, X.Z. and Y.T.; supervision, S.J., C.J. and J.W.; project administration, S.J. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China, Grant Number 41876103.  
Not applicable.  
All data are actual measurement data from sea experiments.  
We would like to thank the Editor and the anonymous reviewers for their valuable comments and suggestions, which greatly improved the quality of this paper.  
The authors have no conflict of interest to declare that are relevant to the content of this article. All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest or non-financial interest in the subject matter or materials discussed in this manuscript.