## 3 System Architecture of the Proposed IPSS Maintenance Assistance Platform
The processed data are displayed on the engineer's dedicated GUI (Step 2, engineer side), which includes a list of all products as well as an estimation of the remaining time in which a specific manufacturer's equipment will arrive at the manufacturer's facility for maintenance. Figure 3: Proposed system architecture derived from [21]. In an attempt to further facilitate the engineering department of the equipment manufacturer, a Graphical User Interface (GUI) for monitoring the status/health of the online customer equipment is utilized. This can be realized in Figure 3, in the engineering layer, Steps a through c. A similar GUI is also provisioned for the clients, from which the customer can quickly scan their equipment with a smart device and visualize their status. In the case that the equipment health is low, through the proposed AR interface, the client can send snapshots of the equipment and send them via the Cloud Database to the engineering department of the OEM in order to initiate the scheduling process of the maintenance (please refer to Figure 3, customer layer, Step 2). Further to that, customers can send media files (e.g., images, video) via the Cloud platform when the manufacturer's equipment is delivered for maintenance (Step 3). The aim of this functionality is to fully digitize the process of equipment maintenance, by gathering a wide variety of data that can be later used by the manufacturer in order to further reduce the equipment inspection time as well as to facilitate communication of the two involved parties. Following the initial communication of the two parties, the customer is responsible for delivering the equipment to the premises of the maintenance contractor, i.e., the PSS provider, where the manufactured equipment is inspected in detail by the engineering department. Afterwards, the engineering department is responsible for composing BOM BOP, as indicated in Figure 3, in Step 4. The result of this process is the generation of a report including an estimation of the time and cost maintenance processes and spare parts. This functionality supports sending the report to the customer, in order to approve it and therefore grant the maintenance contractor permission to proceed with the maintenance of the equipment. As discussed in previous paragraphs, the maintenance process is supported by AR instructions which are generated by a smart precedence algorithm (please see Step 5 in Figure 3 [65]). The precedence algorithm accepts the CAD assembly of the equipment as the input and the output is an XML file with the sequence of assembly or disassembly of the equipment. Likewise, the algorithm also outputs the axis and direction in which each part should be removed or inserted. In the AR GUI, additional functionalities are also provisioned, such as manipulation of the virtual augmentations, in an attempt to improve the users' perception about the assembly, the parts involved, and other geometric features of interest. As far as the Energy Demand Management (EDM) Module, its functionality is based on creation of an ecosystem between the Energy Supply Company (ESC) (I) and the customers (II). The ESC has a specific pricing policy with individual tariffs and aims at the creation of an ecosystem to provide Dynamic Energy Pricing. To accomplish this, an Energy Demand Management service (EDM) is required, which is fed with the \"production-consumption profiles\" of each of the ecosystem's individual industries. The visualization and monitoring of the manufacturers' infrastructures is an innovative feature of the proposed methodology. Wireless data acquisition devices are connected on production equipment and transmit data to a Cloud server. This part aims to provide insights into machine energy usage and to link that information to the energy consumption profile of the corresponding customer. As a result, future energy demand can be forecasted using data from the machines of the company, allowing for peak identification in the energy grid.