RFID in Industry 4.0: The technology’s role in Shop Floor Control’s Operationalisation

. The advent of Information and Communication Technology brought some advances in the field of Operations Management. The RFID, when used as Ordering Coordination System provides benefits not only for Production Control. To identify these benefits, this work used a Systematic Literature Review. The results presented 15 benefits, classified into 4 areas that impact the Shop Floor Control and a framework containing the information flow necessary to operationalise the SFC 4.0. The discussion presented some insights relating the benefits with the maturity level of the entire SFC ecosystem when adopting RFID technology and a brief agenda for future studies in this field of knowledge. It was possible to conclude that although the use of RFID is not new, its use as a premise for SFC operationalisation is yet in its initial stage of maturity, which could be reinforced by the fact that the most cited benefits were related to the initial stage of informational flow presented in the framework.


Introduction
The advent of technology, changes in marketing requirements, and the evolution of Information and Communication Technologies (ICT) have brought some challenges to organisations, grounding the natural development of the Strategic Paradigm of Manufacturing Management (SPMM).This evolution, however, got complexity for Shop Floor Control due to the Work In Process and Batch Size reduction, highly customised products required in a short period, with high-quality standards.[1] pointed out that Shop Floor Control Systems (SFCS) was developed to overcome these problems.According to [2], the main issues that this approach seeks to solve are related to productivity, improved management of SF information, reduced complexity in terms of information handling, and facilitated decision-making process.For [1], Shop Floor Managers face unpredictable risks in day-to-day operation, such as errors, defects in the supplies of components, failures, and machines breakdown.The problem of these occurrences in 4.0 environments depends on the dynamicity that evolves these environments.In traditional paradigms, the risks or events are reported only days or even monthly [3].This fact imposes high inertia to solve operational problems related to SFC.Notwithstanding these issues, organisations face fluctuation in the demand and lead times, making a planned production control strategy unreliable.The use of the Radio Frequency Identification (RFID) technology as Ordering Coordination System (OCS) for Industry 4.0 was proposed by [4] to operationalise Shop Floor Control 4.0.Despite this proposal and the high number of studies considering RFID application, not only in manufacturing environment but also in the entire Supply Chain Management, to the best of our knowledge, no work systematically collects and analyses the benefits of RFID adoption as OCS for SFC in 4.0 environments.To fill this gap is just the objective of this research.Therefore, we use a SLR to collect and critically analyse the existing knowledge in this field of knowledge.To address the proposed objective, this study has three interrelated questions: 1-What are the benefits of RFID technology in SFC 4.0?2-How do these benefits impact (allow the operationalisation) of the SFC 4.0?3-What does the identified state of the art say about new research opportunities?Thus, the remainder of this paper is organised as described: Section 2 presents the theoretical background.Section 3 contains the methodological aspects.Section 4 shows the results.Section 5 discusses the results proposing a brief research agenda, and Section 6 offers the conclusion, inferring about theoretical and practical implications of this research.

2
Theoretical Background: Shop Floor Control and RFID

Industry 4.0, Shop Floor Control and RFID, an Integrated Approach
The complexity and dynamics of the manufacturing environment are growing due to the changes in manufacturing demand, requiring some types of products, small lot sizes, and short lead-time to market [5].To meet these new requirements, the Industry 4.0 SPMM, which, in its essence, is composed of disruptive technologies responsible for giving "intelligence" to the cyber part of a physical entity, has data acquisition as a premise.Strongly interrelated with the Fourth Industrial Revolution, RFID is an important, source of Shop Floor Control (SFC) operationalisation in a 4.0 environment.To summarise, Industry 4.0 utilises technology such as Cloud Computing, Big Data and Analytics and Digital Twin to evolute the machinery from automation to autonomy.Considering this evolution, the autonomy level is not acquired by a single machine but by the entire system, called Machine to Machine communication (M2M Communication).
Concerning SFC, we adopt the Gartner definition, for whom SFC is a system of computers and controllers tools used to schedule, dispatch and track the progress of work orders through manufacturing based on defined routings [6].This area is one of the most challenging for manufacturing managers, given the infinity possibility of disruptions that involve machinery, operators, raw material and others.For each set of volume-variety combinations, there is an OCS that better fits the Manufacturing system's objective.In Industry 4.0, a consensus is being established about RFID as an OCS [7].
Regarding RFID, [8] points to this technology as the primary source of data generation in intelligent environments, such as Smart Factories.Being found in standard and long-range formats, the RFID, according to [8], has the fastest recognition speed and can read tags up to 15 meters, being suitable for factory usage.When IoT and RFID are applied to the manufacturing process, heterogeneous RFID-based data, realtime and substantial data, are generated and recorded, called industrial Big Data [9].Big Data is an Input for Analytics to treat and identify unknown relationships among data, which provide feedback to the system, adjust manufacturing and machines parameters, and serve as a basis for decision making.

Research's Methodological Sequence
This study is theoretical-conceptual and presents a literature review on RFID applied to SFC 4.0 as the first attempt to show and explain the benefits of this technology for operations, proposing a literature classification and analysis.[10] points that a SLR is an essential endeavour by itself and not merely a review of previous writing.Moreover, it responds to specific questions and is a "methodology that locates existing studies, selects and evaluates contributions, analyses and synthesises data, and reports the evidence to allow reasonable, clear conclusions about what is and is not known [11].
In addition, this SLR takes the three steps proposed by [12], comprised of Planning, Conduction and Dissemination.The Planning step is summarised in the research protocol (Table 01).The defined parameters were applied in the conducting stage, and the scanning process was then started.In the dissemination stage, the data were treated, and results were presented.The step-by-step is detailed in the following subsections.

Planning Stage
The research criteria are summarised in the following table.Source: The authors To screen the papers, we utilise the Software StArt.The screening process adopted is summarised in figure 1.  Regarding the results, table 02 presents the benefits according to their respective area of impact.Maintenance Management was responsible for 06 benefits (24%), Quality Management was responsible for 04 benefits (16%), the same percentage as the Financial Impacts group.The last group, Operations Management, were responsible for 11 benefits (44%), being the most impacted area.The table also shows a code and description of each capability.This code allows us to insert the capabilities in the software NVivo 11, verifying the existence of any semantical similarity.The last row, containing the authors, shows many times the ability was pointed, considering the sample analysed.Of the 27 Benefits, the most cited one was Real-Time Monitoring (pointed out by 62,80% of the authors.The second most cited benefit is Decision-Making optimisation.This benefit was cited by 18,60% of the authors.The third benefit with more studies is the Flexible Real-time Shop Floor Scheduling, with 16,29% of the studies.To better illustrate the objective of this research, a framework containing the informational flow between the physical and the cyber elements of an ecosystem for SFC 4.0 is above presented.Figure 3 describes the informational flow between physical and cyber elements that compose an ecosystem 4.0 for Shop Floor Control.In this framework, the RFID, responsible for data-gathering, collects and uploads information for Big Data.An Analytics threats the data and identifies the relationship between variables.These relationships and opportunities for continuous improvement are tested in a Digital Twin, and if any gain is identified, the parameter is replaced with the physical machine.

Discussion
RFID technology is the main point of data gathering in SFC 4.0.Soon, it's a premise for SFC 4.0 operationalization.Analyzing the framework (Figure 3), is it possible to perceive that the informational flow that walks throughout the SFC, from raw material to the feedback point, in the Digital Twin, pass to 7 phases.Considering that the more phases organizations has, the higher is the maturity level of its SFC 4.0.Building a parallel with the benefits presented in table 2, we can perceive that the benefits with highest number of citation is related to the initial stages of implementation of the ecosystem 4.0, as real-time monitoring and decision making optimization.Benefits that directly depends on high maturity level as the development of digital maintenance, didn't receive a high number of citation.Thus, we propose a research agenda, according to the four areas where the benefits were previously classified: • Maintenance Management: Although data gathering allow diverse maintenance approaches as presented in table 2, some researches could to focus on the integration of different approaches and its impacts in the main Key Process Indicators of the maintenance area; • Quality Management: With the autonomy level acquired with a complete SFC 4.0 ecosystem, the quality managers and staff's role needs to be studied; • Financial Impacts: Researches focus on internal cost minimization, however, future researches could focus on the implementation cost to build a SFC 4.0; • Operation Management: Researches could to focus on the development of the final stages of SFC 4.0 as, the stages that allows feedbacks for a complete loop evolving an autonomy continuous improvement system; • Integrated approaches as ISM/Fuzzy MICMAC could to hierarchize the benefits, in order to provides a roadmap for RFID adoption as OCS for SFC 4.0;

Conclusions
The RFID technology is not new, but its use as a premise for SFC 4.0 operationalisation is yet in the initial stage.Taking part in this work, it was possible to identify and classify the benefits provided by adopting RFID technology in SFC as a premise for Smart Shop Floor Control.These benefits were scattered in the literature and cited according to researchers' interests.After systematically reviewing the selected papers, state of the art was identified, and a plan for future research was then proposed.This research, like any other, has its limitations, some of them related to the SLR method.
We hope this study could be seen as a source for many others derived from the results here presented.

NR- 1 :
) OR (Data Collection AND Production Control) OR (Database AND Production Control) OR (Data Acquisition AND Production Control) OR (Data Processing AND Production Control) OR (Data Processing AND Production Control) OR (Data Management AND Production Control) OR (Smart Support AND Production Control) OR (Data Driving Simulation AND Production Control) OR (Data Driving Simulation AND Production Control) OR (Data Driving Simulation AND Production Control) OR (Data Driving Production Control) OR (Data-Driven AND Production Control)) AND ((shop floor) OR (Order Progress) OR (Order Monitoring) OR (Order Releas*) OR (Production Scheduling) OR (Production Sequencing) OR (Production Control) OR (Production Scheduling)) AND ((Industry 4.0) OR (Industrie 4.0) OR (Fourth Industrial Revolution) OR (Smart Factor*) OR (Smart Production) OR (digiti?ation) OR (digitali?ation)OR (Virtual factor*) OR (digital factor*) OR (data driven production) OR (real time production) OR (data collection) OR (machine learning) OR (Shop Floor) OR (data acquisition) OR (Data processing) OR (order progress) OR (Order release) OR (order monitoring)) Articles considering other disruptive technologies; NR-2: The definition of "RFID" is not related to the Operational Environment; (LR) LR: Articles that cite RFID but do not express discussion about the role of this technology in the 4.0's Shop Floor Control Inclusion (PR) PR: Articles that focus on one or a few benefits/barriers of RFID (CR) CR: Articles featuring RFID studies, pointing out benefits and their relationship with internal organisational functions;

Figure 1 :
Figure 1: Summary of article's selection

Figure 2 .
Figure 2. Papers published by year

Figure 3 .
Figure 3. Informational Flow between Physical and Cyber resources in SFC 4.0

Table 01 :
Research Protocol