## 3 Qualitative Analysis of the Application of AR in Industrial Assistance and Training
### AR Immersive Learning  
The industrial field demands a high level of visuospatial skills, which have been limited due to the limited visualisation capabilities of traditional 2D designs. The incorporation of AR is presented as an answer to enrich and improve the training experience in multiple aspects.  
In the field of _interactive learning_, AR has fostered the creation of virtual and interactive learning systems. For instance, [PERSON] and [PERSON] [41] presented an AR-based immersive e-learning system utilising a dynamic tracking technique. [PERSON] et al. [52] developed an interactive AR-based tool for assembly line training that facilitates the planning of projects and the monitoring of equipment and processes by operators. These AR-based solutions are designed to guide workers in comprehending complex industrial processes by enabling the visualisation and transmission of interactive information related to physical behaviour.  
In _skill development_, [PERSON] et al. [53] designed an AR-based teaching and training system for industrial applications, which enhanced students' comprehension and abilities in overseeing and directing operational designs on assembly lines. Furthermore, innovative teaching tools have been implemented, such as the content-authoring case study by [PERSON] et al. [56], which concentrated on developing operators' practical abilities through AR in small Industry 4.0 companies.  
_Simulated-based training_ through AR has been employed to address limitations such as overcrowded classrooms or a lack of adequate training equipment. [PERSON] et al. [40] developed an AR training platform for assembly and maintenance skills, providing immersive lab-based training systems to guide students through industrial maintenance tasks. Meanwhile, [PERSON] et al. [68] investigated the potential of AR for training workers by recreating industrial environments and superimposing images as a teaching tool, thus bringing hands-on experience into the classroom. Following this line of enquiry, the study by [PERSON] et al. [95] provided a mobile AR application that simulates the CNC machining process, facilitating interactive learning and skill development in a safe and controlled environment. This immersive training modality enhances students' hands-on experience, making the learning process more immersive and effective.  
In the area of _risk-free learning_, AR has made significant contributions. [PERSON] et al. [44] conducted a detailed analysis of AR assembly line research, highlighting the inherent complexity and risks and emphasising the importance of immersive, safety-oriented learning. Training in real environments frequently fails to adequately address safety issues, which is why the virtuality of AR has been employed to establish a safer approach in the industrial sector. The study indicates that AR can enhance specific aspects of safety training, with positive feedback from participants. The immersive learning environment generated by AR not only captures students' interest in safety issues but also increases their enthusiasm for learning.