# AR-Assisted Guidance for Assembly and Maintenance of Avionics Equipment
## 2 Related works
### AR-Assisted Assembly Guidance  
AR technology has been researched and applied in product design, maintenance, assembly training, and many other fields. The assembly process of the Boeing B787 uses AR technology to assist the assembly of inner wiring harnesses in the fuselage to solve the mis-installation problem caused by mutual occlusion of wires and cables [27]. The assembly error rate has been reduced by 50% and the assembly time has been shortened by 25%. AR technology is also applied in the seat assembly of the Airbus A330, which improves the assembly efficiency by 90% and reduces the level of skill requirements for workers [28].  
[PERSON] [29] introduced AR technology in the early design stage and developed an AR design and assembly system which can detect assembly constraints and perform collision simulation for real assembly. The system simulates the manual assembly process and improves the intuitiveness and interactivity of integrated design and assembly planning. [PERSON] [30] conducted an AR maintenance study, using a head-mounted display to repair the LAV-25A1 armored personnel carrier turret, using arrows, text, labels, close-up views, and virtual models to guide the attention of maintenance personnel and assist in the maintenance task, significantly improving the level of equipment maintenance in the US military. [PERSON] [31] developed a maintenance-oriented AR prototype system, which automatically generates AR content required for industrial maintenance operations through spatial semantic perception and is used to guide other maintenance personnel to inspect and maintain their work, improve the work efficiency of maintenance personnel through adaptive data management, and reduce the technical level requirements for programmers to customize AR content according to scenarios. [PERSON] [32] developed an AR system based on projection, which guides and assists operators to complete manual assembly of electronic components by accurately projecting assembly information, thus shortening operators' skill training time, improving operators' ability to adapt to complex and changeable production processes, and reducing assembly errors. [PERSON] [33] applied the AR application development platform of Unity 3D and Vuforia Engine to display measurement sensor data in an ARheadset with virtual information and provided guidance information for assembly workers based on the measurement data, thus reducing the operation time and error probability of workers. Auxiliary assembly of the car body is realized, but the AR application system relies on the accurate measurement data of the measurement sensor, which affects the stability of the human-computer interaction content trigger.  
In terms of AR assembly guidance in the blind area of the visual field, [PERSON] [34] used AR to provide assembly guidance of an occluded part in a blind insertion task for an assembled object. [PERSON] [35] proposed an AR assembly guidance method to provide auxiliary guidance in a free-hand bolt assembly task in a blind area. [PERSON] [36] developed an AR auxiliary maintenance system to guide workers to complete manual maintenance tasks on machines in gas-fired radiant heating systems.  
AR technology has been studied and applied in many fields and has achieved certain results in mechanical product design [37], simulation [1], assembly [38], maintenance [39], inspection [40], training [41], and other aspects. However, due to the high cost of hardware equipment and the relatively basic technical theory, the application scenarios are limited and have not been widely popularized.