Investigating Fog- and Cloud-based Control Loops for Future Smart Factories

Abstract: In the recent years we have seen that internet connectivity has multiplied vastly and that more and more computation and information storage are moved to the cloud. Similarly to other types of networks, industrial systems also see an increase in the number of communicating devices. Introduction of wireless communication into industrial systems instead of currently used wired networks will allow interconnection of all kinds of stationary and mobile machinery, robots and sensors and thereby bring multiple benefits. Moreover, recent developments in cloud and fog computing open many new opportunities in control, analysis and maintenance of industrial systems. Wireless systems are easy to install and maintain and relocation of data analysis and control services from local controllers to the cloud can make possible computations requiring a lot of resources, improve efficiency of collaboration between different parts of a plant or several plans as cloud servers will be able to store information and be accessible from all of them. However, even though introduction of wireless communication and cloud services brings a lot of benefits, new challenges in fulfilling industrial requirements arise as, e.g., packet delivery rates might be affected by disturbances introduced in wireless channels, data storage on distant servers might introduce timing and security issues, resource allocation and reservation for controllers supervising multiple processes should be considered to provide real-time services. The main goal of this thesis work is to consider design possibilities for a factory including local and cloud controllers, i.e. look at how the work of the factory should be organized, where control decisions should be made, analyze pros and cons of making the decisions at local (fog) and cloud servers. To narrow down the problem, an example factory with who independent wireless networks (each consisting of one sensor, one actuator and one local control node) and a cloud controller controlling both of them will be considered. Selected structure allows all the questions of interest to be considered, while its prototype can be built using available for this thesis work equipment