# IoT-Aware Architecture to Guarantee Safety of Maintenance Operators in Industrial Plants
## 1 Introduction
In addition, the safety minimum levels (e.g., the safety stop and the safety reduced speed functions, the proper safety integrity level (SIL), and the Performance Level (PL)) should be calculated with a given standard that depends on the machine type or by architecture used for the implementation [5; 6]. Furthermore, the modification of the machine or its correct maintenance procedure without the explicit authorization of the manufacturer involves the need to re-mark the machine by the third parties who make changes. However, despite all these laws and regulations, based on the performed literature analysis reported in the related works section, at the moment of writing, the complete and regular respect of the reported procedures is not completely supervised by comprehensive ecosystems able to monitor all the hazard situations and notify the right people in case of problems. In this context, the project reported by [PERSON] et al. [7] aims exactly at realizing a smart system based on IoT technologies to enhance worker safety in maintenance procedures. This paper presents the architecture of the innovative system designed within the project. It aims at guiding operators step by step while real-time monitoring the plant, the machine, and the other employees working in the same area. During the maintenance procedure, the operator is guided in the proper execution of each maintenance step and an autonomous IoT system monitors the status of the different parts of the plants and machinery to, then, authorize and show the next steps foreseen in the maintenance process. Within the present paper, a prototype of the system has been implemented to evaluate its feasibility and effectiveness of the system. Various works already presented solutions to support industrial plants maintenance by making predictions on various aspects and operations as demonstrated in the related works section, but they have not been effective in supporting operators, administrators and supervisors throughout their maintenance activities to prevent \"reasonably foreseeable misuse\" of the plant or the machinery that they have to maintain through the exploitation of IoT sensors and other technologies fully integrated with the machinery. It represents the main innovative contribution of this paper that presents an innovative system able to guide the operators during their work, let them chat with experts, and be fully integrated with the machines to, then, generate alerts in case of dangerous situations. The rest of the paper is organized as follows: Section 2 describes the regulatory normative about risk reduction and the standards in machinery taken into consideration throughout the current work. Section 3 presents the related works that inspired the definition of the Requirements and the Running Scenario reported in Section 4. Then, Section 5 presents the proposed system architecture and Section 6 reports the implementation of its different modules. In Section 7, the definition of a real procedure faced by a maintenance operator is exploited to describe how the system works and, therefore, how each component acts in a real situation. Furthermore, Section 8 discusses the main benefits brought by our proposal, and, finally, we present conclusions and recommendations for future works in Section 9.