Elsevier

Computer Communications

Volume 36, Issue 1, 1 December 2012, Pages 42-50
Computer Communications

Real-time personal protective equipment monitoring system

https://doi.org/10.1016/j.comcom.2012.01.005Get rights and content

Abstract

The use of personal protective equipment (PPEs) in the construction industry is necessary to guarantee the safety of the workers. However, this equipment is not usually worn properly. Nowadays, the only control performed over the use of PPEs consists of a visual inspection. This paper introduces a novel cyber-physical system (CPS) to check in real time how the PPEs are worn by the workers. In order to perform such a control, an architecture composed of a wireless local area network and a body area network is considered. A system prototype was developed by using Zigbee and RFID technologies that support the deployment of both kinds of networks. The worker carries a microcontroller-based device that detects the presence of the PPEs and sends a report to a central unit where alerts and historical data are generated. This paper is basically aimed at introducing the monitoring system, describing its hardware and software components, and analyzing the coverage and consumption of the worker’s device.

Introduction

In recent years society has been demanding enhanced mechanisms to prevent occupational hazards. The construction industry is a field with a particular interest in this topic. In this industry workers have to follow several working rules. If they are not followed, the responsibility lies with the construction company. Some of the most important rules on a building site are related to the use of protective elements, such as helmets, gloves, boots, goggles, harness, etc. These elements are collectively known as personal protective equipment (PPE).

To reduce the accident rate in this type of work, it is required the application of technical and organizational actions. Among these actions, there are several that involve the use of PPEs to prevent harm from uncontrollable risks. Hence, PPEs are the last line of defense for the protection of workers and, therefore, one of the elements an organization should pay attention to, since if they fail, the worker can suffer serious consequences.

The main problem of a PPE-based protection policy arises when workers do not use PPEs (on purpose or not) or when they use them inappropriately. The only current way to avoid this situation is through a visual inspection by a technician. However, this solution is ineffective, since such control is performed only at specific times and it does not allow the performance of PPE traceability or real-time monitoring.

One of the solutions to this problem consists in using smart devices that are embedded in clothing, which lie in the areas of wearable computing [1] and cyber-physical systems (CPS). This paper introduces a novel system that provides real-time information on the use of PPEs. This system is able to determine whether each worker is wearing the required PPEs, monitoring their presence and warning the worker if they are not properly used. The result of the monitoring process is collected at a central server which generates historical records, alerts and any other type of events required for the proper use of the PPEs. In the system proposed each worker wears a body area network (BAN) of sensors that is able to detect the presence of a PPE adjacent to certain parts of the body.

Although the implementation presented is innovative, similar developments have been used in other wearable computing applications: healthcare, games, context awareness and ubiquitous solutions, human activity analysis [2], energy efficiency [3], wearable gestural interfacing [4] and even for monitoring everyday activities [5].

As discussed in this paper, the system introduced integrates different types of networks and technologies. On the one hand there is a mesh network that provides communications support for a real-time view of the status of workers and their PPEs. Moreover, each worker needs to carry a personal network or body area network (BAN) device able to analyze the presence and location of the PPEs used.

Given this scenario, we will show a prototype that uses RFID technology to determine when an employee makes use of a PPE, and that performs mesh network communications using Zigbee. The rest of this paper is structured as follows. Section 2 describes the problem to be solved. Section 3 shows the system architecture. Sections 4 Hardware components, 5 Software components detail the hardware and software components of the system. Section 6 explains the communications protocol and Section 7 shows the results from several performance tests. Finally, Section 8 is devoted to conclusions.

Section snippets

Problem statement

As we mentioned before, our objective is to design and develop a system to check in real time the use of PPEs in the field of construction. Since this system is going to be included in the topic of wearable computing, and taking into account the environment where it is going to be used, the new system has to cover the following goals:

  • Low cost. The system is used in an environment with several workers where each one will wear a device to monitor their PPEs. Thus, the price of each worker’s unit

System architecture

In order to have centralized information of the workers in real time, the system requires two kinds of network: a mesh network and a BAN.

Fig. 1 shows a typical structure of a mesh network where we can see three kinds of devices1:

  • Coordinator

    This device collects the information coming from the worker’s device, which is called “End node”. The coordinator has the following capabilities:

Hardware components

In order to develop a prototype and satisfy the requirements of the system, we have decided to use standard technologies. In particular, we have used RFID for detecting tags attached to PPEs and Zigbee as the technology for the mesh network. The following subsections provide the specific details of the system components are exposed.

Microcontroller software

It is important to note that thanks to the use of an ATmega1280, the software of the microcontroller can be developed with the IDE from the Arduino project [9], which uses a programming language very similar to C/C++. The microcontroller software performs the following main tasks:

  • Initialization of the serial ports to communicate through the Zigbee module and with the RFID reader.

  • Periodical detection and validation of the RFID UIDs.

  • Reception of the configuration from the coordination node

Protocol

The system needs a protocol to enable the mesh network interaction between the end nodes and the coordinator to take place. The control flow must be very clear and precise, in order to prevent any data loss caused by typical situations that commonly occur in wireless systems, such as power failure, coverage loss, packet loss, etc. With this objective, timeout-acknowledgement mechanisms are implicitly assumed in communications, although they have not been represented in the following diagram.

Prototype tests

Several tests dealing with coverage and power consumption were done in order to evaluate prototype performance.

Conclusions

This paper has introduced a novel system to control the use of PPEs (personal protective equipment) in the construction industry, allowing the checking in real time of how workers use the PPEs.

An architecture composed of two kinds of network, a mesh network and a BAN, was presented. The mesh network is needed to transmit information gathered from devices worn by the workers. These devices, called end nodes, make use of a BAN in order to distribute several PPE detectors (readers) in the

Acknowledgment

This work has been supported by 09TMT005CT (Xunta de Galicia, Spain) and IPT-020000-2010-35 (Ministerio de Ciencia e Innovación, Spain with FEDER funds of the European Union).

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