# AR-Assisted Guidance for Assembly and Maintenance of Avionics Equipment
## 6 Limitations and Conclusions  
Although the proposed AR-assisted guidance method for visual blind areas improves the efficiency of training, assembly, and maintenance tasks, it also has some limitations. The assembly pose tracking method proposed in this paper has a limited application in terms of objects and scenarios. At present, our method can merely be applied to targets with a certain volume and cannot track small parts such as bolts. And when severe occlusion occurs, the tracking performance will be reduced or even invalid, making it difficult for the system to automatically identify the assembly steps, and human-computer interaction methods such as speech are needed to move on to the next step. Moreover, the computing power of the hardware equipment used in this experiment is limited. Continuous use for a long time will lead to hardware overheating and frequency reduction, resulting in instability of the algorithm. We will improve this the future work by adjusting the algorithm parameters and structure, as well as transferring the computational work to high-performance hardware. There is redundancy in the presentation of the AR guidance information. We provide AR assembly guidance information, including translucent highlighting rendering of assembly locations, 3D assembly animation, arrows, curves, circles, voices, and text information such as assembly steps. However, some information may not be focused on by participants or may not be presented in the best form. Redundant AR graphics may reduce the efficiency of AR guidance and increase the mental burden of users. In the future, we will consider the user experience and optimize the presentation form of AR information. The task scenario in the user study was limited and the participants were limited to graduate students with assembly experience. The assembly task is only for avionics, and the space in the equipment bay is relatively narrow. And for skilled workers on actual production lines, the AR guidance method may be less helpful. In future work, we will propose more AR methods applicable to engineering sites to help improve production efficiency. In this paper, an AR-assisted guidance method for assembly in visual blind areas was developed. Firstly, we proposed an anti-occlusion tracking method for assembly parts integrating multi-modality information. Then, we proposed an assembly step identification and guidance method. The blind-area visualization and auxiliary guidance system was applied in the assembly and maintenance of avionics equipment. We designed and conducted user experiments in three tasks: training, assembly, and maintenance. The results show that the AR-assisted guidance method had a significantly lower completion time for all tasks compared to the traditional guidance method and that it has better learnability and usability. Moreover, less mental effort is required by the operator with the AR guidance method, which translates into excellent effectiveness and feasibility. Conceptualization, Z.X. and J.Y. ; methodology, Z.X. and Q.L. ; software, Q.L. and Z.X. ; validation, R.C., Z.X. and Q.L. ; formal analysis, Z.X. ; resources, X.M. ; data curation, Q.H. ; writing--original draft preparation, Z.X. ; writing--review and editing, Z.X., Q.H. and R.C. ; visualization, Q.L. ; project administration, J.Y. and Z.X. ; funding acquisition, J.Y. and X.M. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Key Research and Development Program of China, grant number 2021 YFB1714900. The study was conducted according to the guidelines of the Declaration of Helsinki, and approved by the Committee of School of Mechanical Engineering, Xi'an Jiaotong University (protocol code: XJTUAE2023-121304, approve date: 9 December 2023). Informed Consent Statement: Informed consent was obtained from all subjects involved in the study. The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy concerns.