# Towards a Flexible Smart Factory with a Dynamic Resource Orchestration
## 1 Introduction  
Originating in Germany as Industry 4.0 (4.0), the claim that society is amidst the fourth industrial revolution has been accepted and widely developed in the past decade [1, 2]. Several governmental programs and paradigm-shifting initiatives that support and promote the idea are growing worldwide, with the most elaborated industries being in front--from 'Smart manufacturing' in the United States and 'Made Smarter' in the UK, to 'Made in China 2025' [2, 3]. The scientific research community, although it sometimes struggles with the multi-disciplinary nature and wide perspectives of I4.0, has also given an impetus to great change [4, 5]. In the I4.0 era, manufacturers are not only required to invest in technological infrastructure but also need to reconsider their existing business models and resources--including humans--to adapt quickly to changes in perspective [6]. Continuous adjustment to a human workforce is particularly important in Europe, where jobs involving manual work still constitute the second-largest category within the manufacturing sector [7]. I4.0 is faced with the challenge of blurred boundaries between the physical, digital, and biological worlds integrating new digital technologies into production processes. In addition, there is strong customer demand for highly customised products that are: with prices near to mass production, of increased quality, and need a short time to be delivered. Therefore, all manufacturers--in particular, Small and Medium-Sized Enterprises (SME)--need to adapt quickly to new trends and answer to the ever-growing list of requirements if they are to endure this revolution [8, 9]. Smart Factory (SF) is nowadays a common term encapsulating the vision for factories of the future. The creation of a Smart Factory is one of the most frequent directions taken when applying I4.0, for both the scientific community and manufacturers [9]. Althoughmany envision smart factories to be built from the ground up, thus having the total disruption, existing factories can be made'smarter' by adapting them with the current technology. The introduction of the idea of enriching the existing device with a cyber component has gradually led to the wide acceptance of the Cyber-Physical Systems (CPS) as one of the key enabling technologies of SF and I4.0 [4; 5]. A legacy device can be enriched with cyber interfaces and transformed into CPS in what could be considered retrofitting. Therefore, by using the know-how already gained in the past two decades, it is possible to partially retrofit, and thus adapt, the existing production systems into a flexible manufacturing system of the next generation. Such manufacturing systems are self-organised networks of machines, products, humans, and conveyors--the so-called cyber-physical production system (CPPS). By retrofitting legacy equipment and information systems, it will not matter what type the production participant is, as long as it can communicate with the complete CPPS. Additionally, the I4.0 movement is not gravitating towards workerless production facilities, unlike the CIM approach popular at the end of the last century. It is rather motivated to integrate people into this cyber-physical structure to maximise their potential [10]. Therefore, it will be essential to enable safe and fluent cooperation of human workers with other--smart and legacy--resources [6]. Recent advances in production research forecast that future production and manufacturing systems will integrate heterogeneous, decentralised, smart resources, and processes across all organisational levels of control [11]. All factories must gradually become'smart' if they are to facilitate numerous cyber-physical systems communicating and cooperating synchronically with each other and with humans [3; 9]. The communication and cooperation between all the participants in an SF will need to be well orchestrated, from early conceptualisation to late execution of the production. The production systems will reconfigure as frequent as new bespoke products are ordered.