# Review of Microsoft HoloLens Applications over the Past Five Years
## 3 Results
### Applications in Engineering Fields
#### 3.2.1 Industrial Engineering
They analyzed the possibility of using HoloLens to improve the efficiency of remote maintenance operations compared to the telephone-supported maintenance process. The results showed that the completion rate of the consultation using the audio-only system was approximately 20% slower than when using the HoloLens. It also determined that HoloLens' AR is particularly beneficial when inexperienced employees have to perform complex and difficult tasks. [PERSON] et al. [57] proposed an AR-based application program that retrieves and displays a production schedule and processed data for production management. The proposed application is designed and implemented to dynamically exchange information between a digital environment and physical production system. The data were retrieved and loaded within AR-based applications via extensible markup language (XML) format files, then projected onto the Gantt charts and shop floor monitoring modules. HoloLens users can visualize both production Gantt charts and shop floor monitoring in the real world and place them in a comfortable position on the real-world object. Because the proposed application is based on AR technology, users can more easily recognize and manipulate the data. [PERSON] et al. [58] applied AR technology to the wire assembly and production process; in particular, they produced and tested a system prototype for an assistance device for the wiring of control cabinets. The system identifies the elements of the environment online and provides significant support to a particular operator in the control cabinet assembly and production line. The operation process of the system proceeds as follows. (1) A CAD file is loaded into an EPLAN smart wiring (ESW) system (wiring support system). (2) When the user selects a wire displayed in the list of ESW systems via virtual screens or physical touch screens, extended information and data, such as wire length, connection point details and 3D graphics, are displayed. (3) The user collects a wire of an appropriate length from a wire holder. (4) The AR glasses-related software uses certain coordinates provided by ESW's 3D graphics along with particular markers on a cabinet and matching algorithm to indicate the wire's assembly point through virtual arrows, pointers, virtual images with markings, or textual prompts. (5) The user displays the assembly of a particular wire on a virtual touch screen with a simple gesture or voice command. (6) The user collects the next wire and repeats the operation within the process. Figure 8 shows an overview of the production station and general system principle. [PERSON] et al. conducted tests to determine whether the system supported the control cabinet production process. Consequently, it was verified that the wire assembly process can be significantly shortened using an AR glass-based system. [PERSON] and [PERSON] [59] developed a HoloLens headset-based AR application that supports the assembly of ready-to-assemble (RTA) furniture. The users can quickly conceive the spatial relationship of its parts using the visual functions and interaction modes of the developed application. They tested the application on first-time users of RTA furniture. Thus, the application was shown to be effective in improving the user's spatial problem-solving ability when working with RTA furniture with different assembly complexities. The positive effect of the AR-based supports was remarkable against the assembly of higher complexity. [PERSON] et al. [60] developed a new collaboration application based on HoloLens that allows shipyard operators to interact with a virtual clutch, while assembling a turbine in a real workshop. The application acts as a virtual guide, while assembling different parts of a ship. The users can receive information on documents for each part of the clutch using the AR device and check the relevant blueprints and physical measurements. The developed solution was tested, while performing the assembly process of a clutch comprising numerous mobile parts of various shapes and sizes.