# Augmented Reality Applications in Industry 4.0 Environment
## 5 Discussion
### Future Research Areas of AR Applications in I4.0  
AR technology is developing intensively, especially in the industrial environment. In the continuation of the chapter, three research areas within smart manufacturing are identified, which according to previous analyses are the most promising for further research: recognition and position of objects; eye and voice control; the control of industrial systems by using AR.  
1. Recognition and position of objects.  
One of the areas of AR that provides a wide area for research is the localization of the device and object recognition in the working environment. The most important goal is to achieve accurate localization. Global positioning system (GPS) is a good solution for outdoor localization but in the case of indoor environments GPS can hardly be used due to reduced signal strength. Different technologies can be used for indoor positioning, depending on accuracy, cost and scalability. Most methods change from passively receiving information to actively seeking information. For AR applications Wireless Local Area Networks (WLAN), sensor networks, vision-based positioning, RFID, etc., are widely used.  
As already mentioned, the recognition of objects in the environment is usually performed with markers. In addition to markers, predefined 3D object recognition, contextual recognition and spatial recognition using computer vision are also utilized. Using markers is the simplest and seemingly most reliable method. However, devices must be directed at them in order to display associated information. What if the markers are hidden, damaged, or unintentionally displaced? Until they are replaced, the AR application cannot be used.  
Since each of these technologies has advantages and disadvantages, many researchers are working to improve the algorithms of these methods and are developing hybrid methods based on a combination of the available technologies [119]. This area provideshuge potential for further development. In the near future, by using cyber physical systems the location of each machine or device will be known in an industrial environment. By creating a digital twin of the entire factory in terms of interactive 3D models and by using these models, the recognition and position of objects can be improved.  
Eye and voice control.  
Based on a review of the literature, it has been observed that there exists a small number of AR applications that include voice commands. An even smaller number of AR applications exist and are based on eye commands. Eye and voice commands are useful because they save time and free the user's hands to perform the task. Due to the nature of the industrial environment, in which a lot of noise is present, it is still difficult to enable the proper functioning of these applications but this opens up avenues for future research.  
The biggest challenges and opportunities for research lie in the control of industrial systems with the help of AR. The I4.0 concept implies the decentralization of industrial systems, where each subsystem has a control unit for itself that communicates with other devices at the factory level. This fact opens the possibility of developing AR applications that will be able to individually control parts of industrial systems, subsystems or even actuators. The main advantage of such a system is the acceleration of maintenance procedures in industrial systems. In cases of intervention, smart workers do not have to go through the user interface, their menus and submenus but can access individual actuators or machine subsystems and manage them directly by using the AR application. Such an application can also represent a link between real systems and their digital twins such that parameters from the AR application are transferred to the cloud, simulated via digital twins and applied to real systems if valid.