# The Application of Augmented Reality in the Automotive Industry: A Systematic Literature Review
## Results
### The Purpose of AR Systems in the Automotive Industry  
The papers were then organized according to the purpose of the research papers. Keeping the same hierarchy presented in Section 2.3, among studies from the first category ('in-car' AR systems) four subcategories were identified (Figure 10). The majority of AR applications (47.37%) are focused on the examination of different display concepts for HUD-like systems or on the effect of visual warnings. In [47] the comparison between two type of AR interfaces (conformal and screen--fixed arrow) was investigated, while also analyzing the driver performance and user attention. The difference between the two display interfaces is that the screen-fixed arrows are rendered at a fixed location on the display screen, while conformal arrows are attached to specific objects in the driver's field of view to draw attention to an object of interest. In [48] it is suggested that conformal AR graphics presented as visual warnings on HUDs can have a positive impact on the driver's behavior. However, [49] showed that animated AR warnings can produce higher judgment accuracy for drivers compared to conformal cues. Other design aspects were dissected in [36; 50; 51]. In [52] two types of warnings (audio and video) were investigated in order to find out their effects on effectiveness and acceptance. AR user acceptance was also addressed in [53]. The impact of visual and haptic augmentation was investigated in [54], showing that they have the potential to reduce divided attention and cognitive load. From the total papers that approaches the subject of 'in-car' systems, 15.79% deal with driving safety improvement. In [55] a HUD system was proposed to display driving safety information under various types of circumstances. Automotive applications for collision avoidance designed to increase driving safety were also presented in [56; 57]. AR has been applied in cooperative systems like vehicle-to-vehicle communication (V2V) in order to obtain visibility of traffic in front of large vehicles [58] or to exchange social information amongst drivers [59]. Researchers have shown that V2V infrastructure and AR interfaces could contribute to improving drivers' behavior and practices, such as reducing aggressive compartment and creating a pro-social attitude [60]. A number of papers do not necessarily specify a field of application for AR; they present a general AR solution, like an improved method or algorithm for a general context. In this subcategory we have included 26.31% of the total number of studies from the 'in-car' AR systems category. New methods for tracking registration [61], crosstalk perception simulation [62], head-pose tracking [63], ghost image elimination [64] and efficient lossless compression [65] are proposed in these papers. For the second category referring to 'other' AR systems, six subcategories were identified: product customization, remote collaboration, general AR solutions, assistance, training and ergonomics (Figure 11). Most of the papers (28.57%) have been included in the 'assistance' subcategory because they present works in which AR is used to assist people in accomplishing various tasks: manual assembly [66; 67; 68] human-robot collaborative assembly [69; 70] and prototyping in the design process [71]. Figure 10: Distribution of papers related to ‘in-car’ AR systems according to their purpose. Ergonomics aspects were evaluated in 23.81% of the articles. Ergonomic research conducted to determine the number of requirements for designing AR systems to assist automotive service technicians were proposed in [72; 73]. A reference model to analyze the experience of workers from the automotive industry was developed in [74]. Other papers were investigating automotive interior ergonomics [75; 76]. A percentage of 19.05% from these papers were classified as part of the 'training' subcategory. In [77] an AR application was presented for a training system in the process of car manual transmission maintenance.