# Remote Technologies as Common Practice in Industrial Maintenance: What Do Experts Say?
### Maintenance and the Importance of Communication  
For a clear understanding, it is necessary to clarify what is meant by maintenance. It is used as a generic term for the specific measures required to maintain functionality. These include servicing, inspection, repair and improvement. The aim is to delay the processes of wear, destruction and decay of the units under consideration in order to guarantee the most trouble-free use possible or to avoid use that is fraught with disadvantages [7]. According to DIN 31051 (German Institute for Standardisation) & Strunz [7] maintenance can be described as an overview term, which is thematically supplemented by its four sub-functions.  
1. **Servicing** is the term used to describe measures to delay the degradation of the existing wear stock, i.e., the preservation of the target condition.
2. **Inspection** is the examination of conformity of the relevant characteristics of an object, through measurement, observation or functional testing, i.e., the determination and assessment of an actual condition.
3. **Repair** is considered to be a physical measure carried out in order to restore the function of a defective object, i.e., the restoration of the target condition.
4. **Improvement** includes the administrative and technical assessment and improvement of the target state of an object without changing the original function.  
Furthermore, DIN EN 13306 (German Institute for Standardisation) distinguishes between preventive and corrective maintenance. The preventive measures of maintenance and inspection are referred to as \"preventive maintenance\", while \"corrective maintenance\" refers to repairs after the occurrence of faults or malfunctions.  
When talking about remote maintenance, several levels of communication can be used. A distinction must be made between the following:  
* **machine-to-machine communication (M2M)**, which describes the automated exchange of information between technical systems, e.g., machines, with each other or with a central office. Typical applications are remote monitoring and control. M2M links information and communication technologies and forms the IoT [8].
* Furthermore, **human-machine interaction**. Here, the machine is in many cases a computer, digital systems or devices for the IoT that contain information and communication technologies and application or information systems [9]. Given the high complexity of modern production facilities, human-machine communication is facing new challenges. The large amount of data collected increases the demands on visualisation, which must be understandable for both maintenance experts and machine operators on site.
* The third level is **human-to-human communication**. An example of this can be seen in Figure 1; it describes the communication in the event of a malfunction between a maintenance expert and a machine operator via various remote technologies such as tablet, data glasses, smartphone. In terms of remote technologies, this can be divided into different levels.
* First, information exchange between two or more people via email or messaging service.
* Second, direct live remote connection with and without image or video transmission via telephone, PC or smartphone.
Third, live remote connection using AR technologies via collaboration software. In addition to video, this allows objects to be drawn and superimposed in the viewing area.